Ryutaku Kaneyama - Academia.edu (original) (raw)

Papers by Ryutaku Kaneyama

Knee Surgery, Sports Traumatology, Arthroscopy, Oct 17, 2023

Orthopaedic Proceedings, Feb 21, 2018

Introduction Bulk bone grafting is commonly used in total hip arthroplasty (THA) for developmenta... more Introduction Bulk bone grafting is commonly used in total hip arthroplasty (THA) for developmental dysplasia. However, it is a technically demanding surgery with several critical issues, including graft resorption, graft collapse, and cup loosening. The purpose of this study is to describe our new bone grafting technique and review the radiographic and clinical results. Patients and Methods We retrospectively reviewed 105 hips in 89 patients who had undergone covered bone grafting (CBG) in total hip arthroplasty for developmental dysplasia. We excluded patients who had any previous surgeries or underwent THA with a femoral shortening osteotomy. According to the Crowe classification, 6 hips were classified as group I, 39 as group II, 40 as group III, and 20 as group IV. Follow-up was at a mean of 4.1 (1 ∼ 6.9) years. The surgery was performed using the direct anterior approach. The acetabulum was reamed as close to the original acetabulum as possible. The pressfit cementless cup was impacted into the original acetabulum. After pressfit fixation of the cup was achieved, several screws were used to reinforce the fixation. Indicating factor for using CBG was a large defect where the acetabular roof angle was more than 45 degrees and the uncovered cup was more than 2 cm (Fig.1). The superior defect of the acetabulum was packed with a sufficient amount of morselized bone using bone dust from the acetabular reamers. Then, the grafted morselized bone was covered with a bone plate from the femoral head. The bone plate was fixed with one screw to compact the morselized bone graft. The patient was allowed to walk bearing full weight immediately after surgery. We measured the height of the hip center from the teardrop line and the pelvic height on anteroposterior roentgenograms of the pelvis and calculated the ratio of the hip center to the pelvic height. We defined the anatomical hip center as the height of the center less than 15 % of the pelvic height, which was nearly equal to 30 mm, because the mean pelvic height was 210 mm. Results The mean height of the hip center was 9.8 (4.1∼18.0) % of the pelvic height and the 101 (96.2%) cups were placed within the anatomical hip center. Radiographically, in all patients, the host-graft interface became distinct and the new cortical bone in the lateral part of the plate bone appeared within 1 year after surgery (Fig.2, 3). We observed no absorption of the plate bone graft and no migration of the cup at the last follow-up. Conclusion CBG technique is simple, because the bone graft is always performed after the pressfit of the cup is achieved. Moreover, patients require no partial weight bearing postoperatively, because the cup is supported by the host bone with the pressfit and additional screws. The CBG technique would be an excellent option for the reconstruction of the acetabulum in patients with severe dysplasia to avoid a high hip center and bulky bone grafting.

Orthopaedic Proceedings, Feb 21, 2018

Objective:Accurate measurement of the extension and flexion gap is important in total knee arthro... more Objective:Accurate measurement of the extension and flexion gap is important in total knee arthroplasty (TKA). Particularly, the flexion gap may be influenced by several factors; therefore, tension of the posterior cruciate ligament (PCL), knee extensor mechanism, and the thigh weight may need to be considered while estimating the flexion gap. However, there is no comprehensive study on the flexion gap, including an assessment of the influence of gravity on the gap. The purpose of this study is to investigate the influence of PCL, knee extensor mechanism, and thigh weight on the flexion gap by using a fresh frozen cadaver.Methods:A fresh frozen lower limb that included the pelvis was used for the assessments. The knee was resected by a measured resection technique and a femoral component was implanted to estimate the component gap. The knee was flexed by precisely 90 degrees using a computer navigation system. The flexion gap was measured in different situations: group A, PCL preserved and patella reduced...

Journal of Bone and Joint Surgery-british Volume, Dec 1, 2013

Background: The direct anterior approach (DAA) is one of the muscle sparing approaches in total h... more Background: The direct anterior approach (DAA) is one of the muscle sparing approaches in total hip arthroplasty (THA). The advantages of the DAA-THA include low dislocation rate, quick recovery with less pain, and accurate implantation. However, complications related to the learning curve have been reported. The aim of this study was to analyze the first 100 cases of DAA-THA performed by 2 surgeons. Methods: The records of first 100 consecutive primary DAA-THAs performed by 2 orthopedic surgeons who have np experience of DAA-THA previously were retrospectively reviewed. All operations were performed using DAA in the supine position without the special traction table. The surgical result, the early clinical results, complications, and accuracy of prosthesis placement were investigated. Results: The mean intraoperative blood loss was 424 ± 216 m. The mean operative time was 55.4 ± 17.5 minutes. One-hundred and ninety-one cups (96%) were placed within the Lewinnek9s safe zone. The overall complication rate was 6% (12 hips), including 5 proximal femoral fracture, 3 stem subsidence, 2 temporal femoral nerve palsy, and 2 cup migration. No revision surgery was required, No postoperative dislocation occurred. Conclusion: We analyzed the first 100 cases of DAA-THA performed by 2 orthopedic surgeons. We concluded that with appropriate training this procedure can be performed safely and effectively without increasing the risk of complications.

Orthopaedic Proceedings, Feb 21, 2018

Introduction Total hip arthroplasty (THA) using short design stem is surging with increasing move... more Introduction Total hip arthroplasty (THA) using short design stem is surging with increasing movement of minimally invasive techniques. Short stems are easier to insert through small incisions preserving muscles. We have used these types of short stems since 2010. Almost all of the patients have shown good clinical results. However, two patients developed fatigue fractures on femurs post operatively. We have reviewed the clinical and radiographic results of these patients. Patients and methods From April 2010, we have performed 621 THAs with short design stems, Microplasty R , Biomet, using a muscle preservation approach, the Direct Anterior Approach (DAA). The age ranged from 31 to 88 years old. Case1: 56y.o. male, BMI 23.1kg/m 2 . Preoperative diagnosis was bilateral osteoarthritis. Simultaneous THAs were performed on bilateral hips. He was allowed to bear as much weight as he could tolerate using an assistive device immediately after surgery, and followed standard hip precautions for the first 3 weeks. He was discharged from hospital seven days after surgery and returned to his job two weeks after surgery. He noticed sudden left thigh pain three weeks after surgery without any obvious cause. Crutches were recommended to partially bear his weight. Six weeks after surgery, a fracture line became visible on the radiographs and new callus formation also became visible. Three months after surgery, he felt no pain and was able to walk without any crutches. Case2: 66y.o. female, BMI 27.5 kg/m 2 . Preoperative diagnosis was bilateral osteoarthritis. THAs were performed on the hips at a six month interval. The right hip was operated on first, followed by the left hip. She was discharged from hospital four days after surgery and returned to her job six weeks after surgery. Two months later after left hip surgery, she suddenly felt pain on her left femur without any obvious cause, and was unable to walk. Three weeks later, X-rays showed fatigue fracture lines and new callus formations. After two or three months using crutches, her pain improved and X-rays showed good callus formation and no stem subsidence. Discussions Several reports showed insufficiency fractures of the pelvis following THA. But most of them occurred due to repetitive stress on fragile bones. But our cases showed no evidence of osteoporosis. They had no history of trauma. But they had some points in common, which were they were bilateral cases and their BMI were not low. The incident rate of fatigue fractures of femur with this short stem THAs was 0.3% in our cases. We suggested that one of the causes of these fatigue fractures was the shortness of the stems. The shortness of the stems concentrate the body weight to limited contact area of the femur, and the stress causes the fatigue fractures. We should consider the risk of fatigue fractures on the patients who are operated on bilaterally. However these two patients showed good callus formations and no stem subsidence after a few weeks of partial weight bearing.

関東整形災害外科学会雑誌, Apr 1, 1997

Journal of Orthopaedic Science, May 1, 2016

Background: The aim of this study was to compare patients' perception of treatment outcome after ... more Background: The aim of this study was to compare patients' perception of treatment outcome after unilateral or simultaneous total hip arthroplasty (THA) using the newly developed Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ). Methods: This study included 429 patients treated with primary THA using a direct anterior approach, namely 304 cases of in the unilateral THA (58 males and 246 females; mean age, 62.3 years) and 125 cases of in the simultaneous bilateral THA (24 males and 101 females; mean age, 58.3 years). Items for evaluation included clinical outcomes and all four aspects of the JHEQ score, namely visual analog scale (VAS), pain, movement, and mental status. Results: The mean operative time per hip was 51.3 ± 19.4 min (range, 22e180 min) in unilateral group and 46.2 ± 15.1 min (range, 26e106 min) in simultaneous bilateral group. The mean operative blood loss per hip was 421.2 ml ± 232.1 ml (range, 70e1300 ml) in unilateral group and 200.8 ± 149.8 ml (range, 30e1040 ml) in simultaneous bilateral group. The total JHEQ score (pain/motion/mental status) improved from 26.5 ± 13.6 (preoperative, 10.1/6.8/9.6) to 69.4 ± 14.8 (1 year postoperatively, 25.1/ 20.5/23.8) in unilateral group and from 21.0 ± 8.2 (preoperative, 11.9/2.3/6.9) to 74.9 ± 9.5 (1 year postoperatively, 27.2/22.6/25.0) in simultaneous bilateral group. These results demonstrated a significant improvement before and after surgery for patients in both groups. There were not major complications such as dislocation, bone fracture, nerve palsy or symptomatic pulmonary embolism were observed. Conclusion: In this study, we observed greater improvement in JHEQ in patients treated with bilateral simultaneous THA than in those treated with unilateral THA. These findings demonstrated that bilateral simultaneous THA was related to high patient satisfaction as well as high safety.

Orthopaedic Proceedings, Feb 21, 2018

Introduction Total hip arthroplasty (THA) is becoming a common procedure because it dramatically ... more Introduction Total hip arthroplasty (THA) is becoming a common procedure because it dramatically relieves the patient9s pain. Accordingly, young patients who hope to take THAs are also increasing. The results of THAs in the young patients have historically shown relatively poor survivorship. However several improvements of components may promise good long term results in active young patients. There was no consensus about the appropriate time for performing THA. The purpose of this study is to review the results of THAs younger than 40 years. Material and methods A retrospective review of 14 primary THAs in 12 patients was conducted. The mean age was 27.0 (range 17–30). Ten were female (83%) and 2 were male (17%). The average follow –up period was 38.3 months (range 18–64). All operations were performed using direct anterior approach (DAA). All patients were allowed full weight bearing as tolerated in the immediate postoperative periods. All were cementless THA and the articulation bearing were ceramic/ceramic in 5 hips (33.3%), metal/highly cross linked polyethylene in 8 hips (53.3%), and ceramic/ highly cross linked polyethylene in 2 hips (13.3%). All patients were followed clinically and radiographically. Patients were evaluated at 4,6,12 weeks and each year postoperatively. Patients were allowed sports at 3 months postoperatively without limitations. Results The underlying etiology was steroid-induced osteonecrosis in 5 patients, alcohol-induced osteonecrosis in 2 patients, developmental dysplasia in 2 patients (1 post osteotomy and 2 conservative therapy), infection in 1 patients, ankylosing spondylitis in 1 patients, and epiphyseal dysplasia in 1 patients. All patients failed conservative treatment. Two patients had prior osteotomy surgeries. Preoperative average JOA score, which is 100 points in full score, was 45 points. Those scores improved to 99 points post operatively. All patients became to walk without any assistive devices. There were no infections and dislocations. Their radiographs showed no loosening, subsidence, and osteolysis. All of their radiographs showed well fixed osseous integrations. Discussion and conclusion Although our patients were very small numbers and follow up periods were not long, all of our patients showed good clinical and radiological results. When conservative treatments failed to relieve their pain, surgical treatments are required to restore their highly active lives. The modern THA has been showed numerous good results in older generations. With modern implants and surgical technique, we can also expect promising results in young patients under the condition with careful and long term follow-up.

Orthopaedic Proceedings, Feb 21, 2018

IntroductionA small medial extension gap (EG) needs posterior soft tissue release to avoid undesi... more IntroductionA small medial extension gap (EG) needs posterior soft tissue release to avoid undesirable additional resection of the distal femur in total knee arthroplasty (TKA). However, the effect...

Bone and Joint Research, Apr 1, 2014

Because posterior cruciate ligament (PCL) resection makes flexion gaps wider in total knee replac... more Because posterior cruciate ligament (PCL) resection makes flexion gaps wider in total knee replacement (TKR), preserving or sacrificing a PCL affects the gap equivalence; however, there are no criteria for the PCL resection that consider gap situations of each knee. This study aims to investigate gap characteristics of knees and to consider the criteria for PCL resection. Methods The extension and flexion gaps were measured, first with the PCL preserved and subsequently with the PCL removed (in cases in which posterior substitute components were selected). The PCL preservation or sacrifice was solely determined by the gap measurement results, without considering other functions of the PCL such as 'roll back.' Results Wide variations were observed in the extension and flexion gaps. The flexion gaps were significantly larger than the extension gaps. Cases with 18 mm or more flexion gap and with larger flexion than extension gap were implanted with cruciate retaining component. A posterior substitute component was implanted with the other cases. Conclusions In order to make adequate gaps, it is important to decide whether to preserve the PCL based on the intra-operative gap measurements made with the PCL intact.

Orthopaedic Proceedings, Feb 21, 2018

Background Pre-operative autologous blood donation is recommended as a means of reducing the need... more Background Pre-operative autologous blood donation is recommended as a means of reducing the need for allogeneic transfusion before simultaneous bilateral total hip arthroplasty (THA). However, there have been few reports on the optimal amount of autologous donation for this procedure. In this study we sought to determine the amount of autologous blood required for patient undergoing simultaneous bilateral THA using the direct anterior approach. Methods We retrospectively enrolled 325 consecutive patients (650 hips) underwent simultaneous bilateral primary THA from January 2012 to June 2014. Thirty-three patients were men and 290 patients were women. The patients’ mean age at THA was 59.1 years. All THAs were performed using the direct anterior approach. Intraoperative blood salvage was applied for all patients and postoperative blood salvage was not applied for any patients. Results The mean intraoperative blood loss and the mean operative time for the bilateral procedure were 413±165 g and 87.2±12.3 minutes, respectively. Two hundreds and forty-one of the 325 patients (74.2%) donated an average of 1.9 (range, 1–2) units of autologous blood before the operation. The mean hemoglobin levels on the preoperative day, postoperative day 1 and postoperative day 5 were 12.5g/dl, 10.5 g/dl and 9.5 g/dl, respectively. Only 1 patient (0.3%) required postoperative transfusions of allogeneic blood. All of the autologous units collected were transfused, and no units were wasted. Conclusion Simultaneous bilateral THA can be performed without allogenic blood transfusion in 99.7% of patients. We could not find out significant effectiveness of an average of 1.9 units of autologous blood donation for this procedure in this study. We concluded that simultaneous bilateral THA can be performed without autologous blood donation in healthy patients without severe hip deformity. Whereas, preoperative donation of autologous blood might be suitable for patients with low body weight or patients with severe hip deformity. The minimally invasive aspect of the direct anterior approach seems to allow a low rate of allogeneic blood transfusion in the study.

Journal of Bone and Joint Surgery-british Volume, Dec 1, 2013

Objective: Accurate measurement of the extension and flexion gap is important in total knee arthr... more Objective: Accurate measurement of the extension and flexion gap is important in total knee arthroplasty (TKA). Particularly, the flexion gap may be influenced by several factors; therefore, tension of the posterior cruciate ligament (PCL), knee extensor mechanism, and the thigh weight may need to be considered while estimating the flexion gap. However, there is no comprehensive study on the flexion gap, including an assessment of the influence of gravity on the gap. The purpose of this study is to investigate the influence of PCL, knee extensor mechanism, and thigh weight on the flexion gap by using a fresh frozen cadaver. Methods: A fresh frozen lower limb that included the pelvis was used for the assessments. The knee was resected by a measured resection technique and a femoral component was implanted to estimate the component gap. The knee was flexed by precisely 90 degrees using a computer navigation system. The flexion gap was measured in different situations: group A, PCL preserved and patella reduced; group B, PCL preserved and patella everted; group C, PCL resected and patella reduced; and group D, PCL resected and patella everted. In each group, the measurements were obtained under 3 different conditions: 1, knee flexed and the lower limb on the operation table under gravity, as is usually done in TKA; 2, hip and knee flexed 90 degrees to avoid the influence of gravity; and 3, knee set in the same position as in condition 1 and the thigh was held by hand to reduce the influence of the thigh weight. Results: The flexion gap differed according to groups and conditions. Group B was larger than group A in most conditions and group D was larger than group C. The flexion gap in group D was the largest among the 4 groups. The extensor mechanism had influences to the flexion gap (Table 1). In groups A and B, the flexion gaps were similar under conditions 1, 2, and 3; however, in groups C and D, the flexion gaps in condition 1 were smaller than those in conditions 2 and 3. The thigh weight condition had influences to the flexion gap when the PCL was resected (Table 2). Conclusion: This is the first systemic report about the influences of PCL, extensor mechanism, and thigh weight on flexion gap measurement in TKA. PCL, extensor mechanism, and thigh weight influence the flexion gap and should be considered during TKA surgery. Especially, careful consideration is necessary to estimate the flexion gap when the PCL is resected and the patella is everted because the flexion gap becomes much wider than other situations.

Journal of Bone and Joint Surgery-british Volume, 2016

Introduction Incorrect restoration of the joint line during total knee arthroplasty (TKA) can res... more Introduction Incorrect restoration of the joint line during total knee arthroplasty (TKA) can result in joint instability, anterior knee pain, limited range of motion, and joint stiffness. Although restoration of the correct joint line (i.e., creating an optimal gap in extension and flexion) should be considered in all TKA procedures, no surgical techniques have been established for restoring it. We performed the femoral posterior condylar precut technique (Kaneyama R. Bone Joint Res. 2014; 3) in 91 TKA cases and evaluated the joint line by measuring the thickness of the surgically removed femoral bone and femoral components. Methods A total of 91 knees in 73 patients who underwent primary TKA between June and December 2013 were reviewed retrospectively. The posterior cruciate ligament was preserved in all patients. First, in the femoral posterior condylar precut technique, the extension gap was created by the measured resection technique. Then we created a temporary gap in flexion 4 mm smaller than that created by the measured resection technique and remove posterior osteophytes and soft tissue for good ligament balance. Once the component gap was determined, final femoral posterior condyle cutting was performed to create an optimal gap and rotation. We evaluated the joint line from the differences in thickness between the surgically removed femoral bone and femoral components, and revised the thickness of the bone saw accordingly. The value was positive when the joint line had been raised and negative when it had been lowered. Results Subjects were 17 men (20 knees) and 56 women (71 knees) with a mean age of 72.6 years. The amount of distal femoral bone surgically removed was 8.5±1.8 mm (medial) and 8.3±2.0 mm (lateral) and that of posterior bone was 9.8±1.2 mm (medial) and 7.2±0.8 mm (lateral). The difference in the joint line was −0.4±2.2 mm (medial) and 0.5±3.9 mm (lateral) in extension and 1.1±2.7 mm (medial) and −0.6±1.9 mm (lateral) in flexion. Discussion There are no established surgical techniques for restoring the joint line. Typically, surgical procedures are decided preoperatively by considering the amount of femoral bone to be surgically removed and rotation and cannot be changed during the operation if the gap is found to be incorrect. In our femoral posterior condylar precut technique, however, is possible to fine-tune it at the final step in surgery, making it possible to control the surgical removal of femoral bone, thereby reducing differences in the joint line.

Journal of Bone and Joint Surgery-british Volume, Dec 1, 2013

Introduction: Total knee arthroplasty (TKA) should aim to adjust the component gap (CG) differenc... more Introduction: Total knee arthroplasty (TKA) should aim to adjust the component gap (CG) difference between extension and flexion. However, this difference cannot be measured without placement of a femoral component. The bone gap reportedly decreases in extension after component setting. In contrast, it may be possible to use the mean value of the CG difference in several patients to adjust femoral resection amount beforehand. The purpose of this study is to evaluate the technique of adjusting CG difference using the mean values with measured resection technique (MRT) in TKA. Materials and methods: The subjects were 222 knees (40 male knees, 182 female knees; mean age 70.4 years). To adjust the CG difference after estimation, the femoral posterior condylar pre-cut technique was used. Extension gap was created by usual bone resection; 4 mm of the femoral posterior condyle was pre-cut, and after all osteophytes and soft tissues had been treated, a pre-cut trial component (thickness of 8 mm for distal femur and 4 mm for posterior condyle without the anterior portion) was mounted, achieving the same condition as the setting of a femoral component in MRT (Fig. 1). When the posterior cruciate ligament (PCL) could be easily preserved by intraoperative gap assessments, the PCL was preserved (190 knees, 86%). Results: The CG measured intraoperatively were 9.4 ± 2.8 mm (mean ± S.D.) in extension and 12.2 ± 2.8 mm in flexion, and the difference (flexion - extension) was 2.8 ± 2.6 mm. The mean difference was not large but the variation was large (−3 ∼ 11 mm). When the acceptable range of CG difference (flexion - extension) is set at 0 to 3 mm, only 57% of the patients were included within this range; when 2 mm of the distal femur was cut beforehand in all patients considering the mean CG difference of 2.8 mm, 53% of the patients were within the acceptable range and 42% had 3 mm resection (Fig. 2). When the acceptable range was expanded to −2 mm to 3 mm, 64% of the patients were in this range, whereas this figure was 76% with an additional 2 mm resection of the distal femur and 72% with 3 mm resection. Even after expanding the acceptable range for CG difference to 5 mm and adjusting the distal femoral cut, one fourth of the patients were outside of the acceptable range (Fig. 3). Discussion: This study showed that the CG using MRT was larger in flexion by a mean of 2.8 mm; however, the variation was too large to manage by larger femoral distal cut according to the mean difference beforehand. Although the PCL was preserved in 190 knees, it is anticipated that gaps in flexion will enlarge when PCL resection is selected for all patients, which may further increase the gap requiring adjustment. To resolve such issues, we use the femoral pre-cut technique and pre-cut trial components. With this method, we can control the CG as we want by adjustment of final femoral bone resection in each patient.

Journal of Bone and Joint Surgery-british Volume, Mar 1, 2013

Introduction Although, the total knee arthroplasty (TKA) procedure is performed to make the same ... more Introduction Although, the total knee arthroplasty (TKA) procedure is performed to make the same extension gap (EG) and flexion gap (FG) of the knee, it is not clear how the gaps can be created equally. According to earlier reports, the gaps after bone resection (bone gaps) differ from the gaps after the trial component of the femur is set (component gaps), because of the thickness of the posterior condyle of the femoral component and the tension of the posterior capsule. The surgeon can only check the component gaps after completing the bone resection and setting the trial component and it difficult to adjust the gaps even when the acquired component gaps are inadequate. To resolve this problem, we developed a “pre-cut trial component” for use in a pre-cut technique for the femoral posterior condyle (Fig. 1). This specially made trial component allows us to check the component gaps before the final bone resection of the femur. Materials and methods The pre-cut trial component is composed of an 8-mm-thick usual distal part and a 4-mm-thick posterior part of the femoral component, and lacks an anterior part of the femoral component. With this pre-cut trail component, 152 knees were investigated. The EG was made by standard resection of distal femur and proximal tibia. The FG was made by a 4 mm pre-cut from the posterior condylar line of the femoral posterior condyle (Fig. 2). The rotation of the pre-cut line is initially decided by anatomical landmarks. Once all of the osteophytes are removed and the bone gaps are checked, the pre-cut trial component is attached to the femur and the component gaps are estimated with the patella reduction (Fig. 3). In our experiments, these gaps were the same as the component gaps after the usual trial component was set via the measured resection technique. Finally, the femur is completely resected according to the measurements of the component gaps with the pre-cut trial component. Results The bone gaps were 18.4±2.4 (mean ± standard deviation) mm in extension and 16.5±2.7 mm in flexion. From these results, the expected component gaps were 10.8±2.7 (bone gap −8) mm in extension and 12.5±2.7 (bone gap −4) mm in flexion. After the pre-cut trial component was set, the measured component gaps were 9.4±2.8 mm in extension and 12.5±2.8 mm in flexion. The EG became 1.5±1.0 mm smaller than expected, and the change of FG was 0.2±0.5 mm. While no large decrease of EG was noted, the variation was not insubstantial (0∼5 mm). Conclusion The difference between the bone gap and component gap is very important for an adequate EG and FG in the TKA procedure. Yet with the conventional technique, the component gap is impossible to estimate before the final bone resection. If unacceptable results are discovered after the component gaps are estimated, the gaps are difficult to correct. With the technique we present here, the component gaps can be checked before final bone resection and truly precise gap control can be attained.

Orthopaedic Proceedings, Sep 1, 2012

Background Minimally invasive surgery is being widely used in the field of total hip arthroplasty... more Background Minimally invasive surgery is being widely used in the field of total hip arthroplasty (THA). The advantages of the direct anterior approach (DAA), which is used in minimally invasive surgery, include low dislocation rate, quick recovery with less pain, and accuracy of prosthesis placement. However, minimally invasive surgery can result in more complications related to the learning curve. The aim of this study was to evaluate the learning curve of DAA-THA performed by a senior resident. Methods Thirty-three consecutive patients (33 hips) who underwent primary THA were enrolled in this study. All operations were performed by a senior resident using DAA in the supine position without the traction table. The surgeon started using DAA exclusively for all cases of primary THA after being trained in this approach for 6 months. Operative time, intraoperative blood loss, complications, and accuracy of prosthesis placement were investigated. Results The mean intraoperative blood loss was 524 mL (range, 130–1650 m L). The mean operative time was 60 min (range, 41–80 min). Radiographic analysis showed an average acetabular anteversion angle of 17.0±3.3°, abduction angle of 37.8±4.3°, and stem alignment of 0±0.8°. Thirty-two (97%) of 33 cups were placed within the Lewinnek9s safe zone. The overall complication rate was 12% (4 of 33 hips), including 1 proximal femoral fracture (salvaged with circumferential wiring), 1 temporary femoral nerve palsy (completely recovered in 2 weeks), 1 stem subsidence (5 mm), and 1 cup migration. Three of these complications were occurred in the first 10 cases. No revision surgery was required, No postoperative dislocation occurred. Conclusion We investigated the learning curve of DAA-THA performed by a senior resident. We considered the first 10 cases as the learning curve, but concluded that with adequate training this procedure can be performed safely and effectively without increasing the risk of complications.

Journal of Bone and Joint Surgery-british Volume, May 1, 2016

Introduction Bulk bone grafting is commonly used in total hip arthroplasty (THA) for developmenta... more Introduction Bulk bone grafting is commonly used in total hip arthroplasty (THA) for developmental dysplasia. However, it is a technically demanding surgery with several critical issues, including graft resorption, graft collapse, and cup loosening. The purpose of this study is to describe our new bone grafting technique and review the radiographic and clinical results. Patients and Methods We retrospectively reviewed 105 hips in 89 patients who had undergone covered bone grafting (CBG) in total hip arthroplasty for developmental dysplasia. We excluded patients who had any previous surgeries or underwent THA with a femoral shortening osteotomy. According to the Crowe classification, 6 hips were classified as group I, 39 as group II, 40 as group III, and 20 as group IV. Follow-up was at a mean of 4.1 (1 ∼ 6.9) years. The surgery was performed using the direct anterior approach. The acetabulum was reamed as close to the original acetabulum as possible. The pressfit cementless cup was impacted into the original acetabulum. After pressfit fixation of the cup was achieved, several screws were used to reinforce the fixation. Indicating factor for using CBG was a large defect where the acetabular roof angle was more than 45 degrees and the uncovered cup was more than 2 cm (Fig.1). The superior defect of the acetabulum was packed with a sufficient amount of morselized bone using bone dust from the acetabular reamers. Then, the grafted morselized bone was covered with a bone plate from the femoral head. The bone plate was fixed with one screw to compact the morselized bone graft. The patient was allowed to walk bearing full weight immediately after surgery. We measured the height of the hip center from the teardrop line and the pelvic height on anteroposterior roentgenograms of the pelvis and calculated the ratio of the hip center to the pelvic height. We defined the anatomical hip center as the height of the center less than 15 % of the pelvic height, which was nearly equal to 30 mm, because the mean pelvic height was 210 mm. Results The mean height of the hip center was 9.8 (4.1∼18.0) % of the pelvic height and the 101 (96.2%) cups were placed within the anatomical hip center. Radiographically, in all patients, the host-graft interface became distinct and the new cortical bone in the lateral part of the plate bone appeared within 1 year after surgery (Fig.2, 3). We observed no absorption of the plate bone graft and no migration of the cup at the last follow-up. Conclusion CBG technique is simple, because the bone graft is always performed after the pressfit of the cup is achieved. Moreover, patients require no partial weight bearing postoperatively, because the cup is supported by the host bone with the pressfit and additional screws. The CBG technique would be an excellent option for the reconstruction of the acetabulum in patients with severe dysplasia to avoid a high hip center and bulky bone grafting.

Chiba medical journal, Oct 1, 2002

Spine, Dec 1, 2006

Study Design. Prospective consecutive series. Objective. To analyze supine and standing radiograp... more Study Design. Prospective consecutive series. Objective. To analyze supine and standing radiographs and the association of back pain using subjective pain criteria. Summary of Background Data. It has been considered that there is little correlation between the degree of collapse of the vertebral body and the level of pain. In previous studies, however, measurements have only been based on supine radiographs. Although there were 2 authors who reported the results of supine lateral and standing lateral radiographs in patients with thoracolumbar vertebral fractures, as far as we know, there has not been any detailed report concerning the correlation between radiologic findings using supine and standing lateral radiographs and back pain. Methods. We examined 100 consecutively treated patients, prospectively. Back pain and the supine and standing radiographs were assessed 1 month after injury. Changes in vertebral wedging rate (WR) from supine to standing position (⌬WR) was reported by the following equation: ⌬WR ϭ WR(standing) Ϫ WR(supine). Results. The median age of the cohort was 75 years (range, 60-89 years). The median VAS of back pain at supine position, at standing position, and when standing erect was 13, 33, and 41, respectively. The median wedging rate on the supine and standing radiographs were 28% and 37%, respectively (P Ͻ 0.001). There was a significant correlation between ⌬WR and back pain when standing erect (r ϭ 0.79, P Ͻ 0.001). Conclusion. Changes in vertebral wedging rate between supine and standing position and its association with back pain may give a clue to the pathogenesis of pain from osteoporotic thoracolumbar vertebral compression fractures.

Knee Surgery, Sports Traumatology, Arthroscopy, Oct 17, 2023

Orthopaedic Proceedings, Feb 21, 2018

Introduction Bulk bone grafting is commonly used in total hip arthroplasty (THA) for developmenta... more Introduction Bulk bone grafting is commonly used in total hip arthroplasty (THA) for developmental dysplasia. However, it is a technically demanding surgery with several critical issues, including graft resorption, graft collapse, and cup loosening. The purpose of this study is to describe our new bone grafting technique and review the radiographic and clinical results. Patients and Methods We retrospectively reviewed 105 hips in 89 patients who had undergone covered bone grafting (CBG) in total hip arthroplasty for developmental dysplasia. We excluded patients who had any previous surgeries or underwent THA with a femoral shortening osteotomy. According to the Crowe classification, 6 hips were classified as group I, 39 as group II, 40 as group III, and 20 as group IV. Follow-up was at a mean of 4.1 (1 ∼ 6.9) years. The surgery was performed using the direct anterior approach. The acetabulum was reamed as close to the original acetabulum as possible. The pressfit cementless cup was impacted into the original acetabulum. After pressfit fixation of the cup was achieved, several screws were used to reinforce the fixation. Indicating factor for using CBG was a large defect where the acetabular roof angle was more than 45 degrees and the uncovered cup was more than 2 cm (Fig.1). The superior defect of the acetabulum was packed with a sufficient amount of morselized bone using bone dust from the acetabular reamers. Then, the grafted morselized bone was covered with a bone plate from the femoral head. The bone plate was fixed with one screw to compact the morselized bone graft. The patient was allowed to walk bearing full weight immediately after surgery. We measured the height of the hip center from the teardrop line and the pelvic height on anteroposterior roentgenograms of the pelvis and calculated the ratio of the hip center to the pelvic height. We defined the anatomical hip center as the height of the center less than 15 % of the pelvic height, which was nearly equal to 30 mm, because the mean pelvic height was 210 mm. Results The mean height of the hip center was 9.8 (4.1∼18.0) % of the pelvic height and the 101 (96.2%) cups were placed within the anatomical hip center. Radiographically, in all patients, the host-graft interface became distinct and the new cortical bone in the lateral part of the plate bone appeared within 1 year after surgery (Fig.2, 3). We observed no absorption of the plate bone graft and no migration of the cup at the last follow-up. Conclusion CBG technique is simple, because the bone graft is always performed after the pressfit of the cup is achieved. Moreover, patients require no partial weight bearing postoperatively, because the cup is supported by the host bone with the pressfit and additional screws. The CBG technique would be an excellent option for the reconstruction of the acetabulum in patients with severe dysplasia to avoid a high hip center and bulky bone grafting.

Orthopaedic Proceedings, Feb 21, 2018

Objective:Accurate measurement of the extension and flexion gap is important in total knee arthro... more Objective:Accurate measurement of the extension and flexion gap is important in total knee arthroplasty (TKA). Particularly, the flexion gap may be influenced by several factors; therefore, tension of the posterior cruciate ligament (PCL), knee extensor mechanism, and the thigh weight may need to be considered while estimating the flexion gap. However, there is no comprehensive study on the flexion gap, including an assessment of the influence of gravity on the gap. The purpose of this study is to investigate the influence of PCL, knee extensor mechanism, and thigh weight on the flexion gap by using a fresh frozen cadaver.Methods:A fresh frozen lower limb that included the pelvis was used for the assessments. The knee was resected by a measured resection technique and a femoral component was implanted to estimate the component gap. The knee was flexed by precisely 90 degrees using a computer navigation system. The flexion gap was measured in different situations: group A, PCL preserved and patella reduced...

Journal of Bone and Joint Surgery-british Volume, Dec 1, 2013

Background: The direct anterior approach (DAA) is one of the muscle sparing approaches in total h... more Background: The direct anterior approach (DAA) is one of the muscle sparing approaches in total hip arthroplasty (THA). The advantages of the DAA-THA include low dislocation rate, quick recovery with less pain, and accurate implantation. However, complications related to the learning curve have been reported. The aim of this study was to analyze the first 100 cases of DAA-THA performed by 2 surgeons. Methods: The records of first 100 consecutive primary DAA-THAs performed by 2 orthopedic surgeons who have np experience of DAA-THA previously were retrospectively reviewed. All operations were performed using DAA in the supine position without the special traction table. The surgical result, the early clinical results, complications, and accuracy of prosthesis placement were investigated. Results: The mean intraoperative blood loss was 424 ± 216 m. The mean operative time was 55.4 ± 17.5 minutes. One-hundred and ninety-one cups (96%) were placed within the Lewinnek9s safe zone. The overall complication rate was 6% (12 hips), including 5 proximal femoral fracture, 3 stem subsidence, 2 temporal femoral nerve palsy, and 2 cup migration. No revision surgery was required, No postoperative dislocation occurred. Conclusion: We analyzed the first 100 cases of DAA-THA performed by 2 orthopedic surgeons. We concluded that with appropriate training this procedure can be performed safely and effectively without increasing the risk of complications.

Orthopaedic Proceedings, Feb 21, 2018

Introduction Total hip arthroplasty (THA) using short design stem is surging with increasing move... more Introduction Total hip arthroplasty (THA) using short design stem is surging with increasing movement of minimally invasive techniques. Short stems are easier to insert through small incisions preserving muscles. We have used these types of short stems since 2010. Almost all of the patients have shown good clinical results. However, two patients developed fatigue fractures on femurs post operatively. We have reviewed the clinical and radiographic results of these patients. Patients and methods From April 2010, we have performed 621 THAs with short design stems, Microplasty R , Biomet, using a muscle preservation approach, the Direct Anterior Approach (DAA). The age ranged from 31 to 88 years old. Case1: 56y.o. male, BMI 23.1kg/m 2 . Preoperative diagnosis was bilateral osteoarthritis. Simultaneous THAs were performed on bilateral hips. He was allowed to bear as much weight as he could tolerate using an assistive device immediately after surgery, and followed standard hip precautions for the first 3 weeks. He was discharged from hospital seven days after surgery and returned to his job two weeks after surgery. He noticed sudden left thigh pain three weeks after surgery without any obvious cause. Crutches were recommended to partially bear his weight. Six weeks after surgery, a fracture line became visible on the radiographs and new callus formation also became visible. Three months after surgery, he felt no pain and was able to walk without any crutches. Case2: 66y.o. female, BMI 27.5 kg/m 2 . Preoperative diagnosis was bilateral osteoarthritis. THAs were performed on the hips at a six month interval. The right hip was operated on first, followed by the left hip. She was discharged from hospital four days after surgery and returned to her job six weeks after surgery. Two months later after left hip surgery, she suddenly felt pain on her left femur without any obvious cause, and was unable to walk. Three weeks later, X-rays showed fatigue fracture lines and new callus formations. After two or three months using crutches, her pain improved and X-rays showed good callus formation and no stem subsidence. Discussions Several reports showed insufficiency fractures of the pelvis following THA. But most of them occurred due to repetitive stress on fragile bones. But our cases showed no evidence of osteoporosis. They had no history of trauma. But they had some points in common, which were they were bilateral cases and their BMI were not low. The incident rate of fatigue fractures of femur with this short stem THAs was 0.3% in our cases. We suggested that one of the causes of these fatigue fractures was the shortness of the stems. The shortness of the stems concentrate the body weight to limited contact area of the femur, and the stress causes the fatigue fractures. We should consider the risk of fatigue fractures on the patients who are operated on bilaterally. However these two patients showed good callus formations and no stem subsidence after a few weeks of partial weight bearing.

関東整形災害外科学会雑誌, Apr 1, 1997

Journal of Orthopaedic Science, May 1, 2016

Background: The aim of this study was to compare patients' perception of treatment outcome after ... more Background: The aim of this study was to compare patients' perception of treatment outcome after unilateral or simultaneous total hip arthroplasty (THA) using the newly developed Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ). Methods: This study included 429 patients treated with primary THA using a direct anterior approach, namely 304 cases of in the unilateral THA (58 males and 246 females; mean age, 62.3 years) and 125 cases of in the simultaneous bilateral THA (24 males and 101 females; mean age, 58.3 years). Items for evaluation included clinical outcomes and all four aspects of the JHEQ score, namely visual analog scale (VAS), pain, movement, and mental status. Results: The mean operative time per hip was 51.3 ± 19.4 min (range, 22e180 min) in unilateral group and 46.2 ± 15.1 min (range, 26e106 min) in simultaneous bilateral group. The mean operative blood loss per hip was 421.2 ml ± 232.1 ml (range, 70e1300 ml) in unilateral group and 200.8 ± 149.8 ml (range, 30e1040 ml) in simultaneous bilateral group. The total JHEQ score (pain/motion/mental status) improved from 26.5 ± 13.6 (preoperative, 10.1/6.8/9.6) to 69.4 ± 14.8 (1 year postoperatively, 25.1/ 20.5/23.8) in unilateral group and from 21.0 ± 8.2 (preoperative, 11.9/2.3/6.9) to 74.9 ± 9.5 (1 year postoperatively, 27.2/22.6/25.0) in simultaneous bilateral group. These results demonstrated a significant improvement before and after surgery for patients in both groups. There were not major complications such as dislocation, bone fracture, nerve palsy or symptomatic pulmonary embolism were observed. Conclusion: In this study, we observed greater improvement in JHEQ in patients treated with bilateral simultaneous THA than in those treated with unilateral THA. These findings demonstrated that bilateral simultaneous THA was related to high patient satisfaction as well as high safety.

Orthopaedic Proceedings, Feb 21, 2018

Introduction Total hip arthroplasty (THA) is becoming a common procedure because it dramatically ... more Introduction Total hip arthroplasty (THA) is becoming a common procedure because it dramatically relieves the patient9s pain. Accordingly, young patients who hope to take THAs are also increasing. The results of THAs in the young patients have historically shown relatively poor survivorship. However several improvements of components may promise good long term results in active young patients. There was no consensus about the appropriate time for performing THA. The purpose of this study is to review the results of THAs younger than 40 years. Material and methods A retrospective review of 14 primary THAs in 12 patients was conducted. The mean age was 27.0 (range 17–30). Ten were female (83%) and 2 were male (17%). The average follow –up period was 38.3 months (range 18–64). All operations were performed using direct anterior approach (DAA). All patients were allowed full weight bearing as tolerated in the immediate postoperative periods. All were cementless THA and the articulation bearing were ceramic/ceramic in 5 hips (33.3%), metal/highly cross linked polyethylene in 8 hips (53.3%), and ceramic/ highly cross linked polyethylene in 2 hips (13.3%). All patients were followed clinically and radiographically. Patients were evaluated at 4,6,12 weeks and each year postoperatively. Patients were allowed sports at 3 months postoperatively without limitations. Results The underlying etiology was steroid-induced osteonecrosis in 5 patients, alcohol-induced osteonecrosis in 2 patients, developmental dysplasia in 2 patients (1 post osteotomy and 2 conservative therapy), infection in 1 patients, ankylosing spondylitis in 1 patients, and epiphyseal dysplasia in 1 patients. All patients failed conservative treatment. Two patients had prior osteotomy surgeries. Preoperative average JOA score, which is 100 points in full score, was 45 points. Those scores improved to 99 points post operatively. All patients became to walk without any assistive devices. There were no infections and dislocations. Their radiographs showed no loosening, subsidence, and osteolysis. All of their radiographs showed well fixed osseous integrations. Discussion and conclusion Although our patients were very small numbers and follow up periods were not long, all of our patients showed good clinical and radiological results. When conservative treatments failed to relieve their pain, surgical treatments are required to restore their highly active lives. The modern THA has been showed numerous good results in older generations. With modern implants and surgical technique, we can also expect promising results in young patients under the condition with careful and long term follow-up.

Orthopaedic Proceedings, Feb 21, 2018

IntroductionA small medial extension gap (EG) needs posterior soft tissue release to avoid undesi... more IntroductionA small medial extension gap (EG) needs posterior soft tissue release to avoid undesirable additional resection of the distal femur in total knee arthroplasty (TKA). However, the effect...

Bone and Joint Research, Apr 1, 2014

Because posterior cruciate ligament (PCL) resection makes flexion gaps wider in total knee replac... more Because posterior cruciate ligament (PCL) resection makes flexion gaps wider in total knee replacement (TKR), preserving or sacrificing a PCL affects the gap equivalence; however, there are no criteria for the PCL resection that consider gap situations of each knee. This study aims to investigate gap characteristics of knees and to consider the criteria for PCL resection. Methods The extension and flexion gaps were measured, first with the PCL preserved and subsequently with the PCL removed (in cases in which posterior substitute components were selected). The PCL preservation or sacrifice was solely determined by the gap measurement results, without considering other functions of the PCL such as 'roll back.' Results Wide variations were observed in the extension and flexion gaps. The flexion gaps were significantly larger than the extension gaps. Cases with 18 mm or more flexion gap and with larger flexion than extension gap were implanted with cruciate retaining component. A posterior substitute component was implanted with the other cases. Conclusions In order to make adequate gaps, it is important to decide whether to preserve the PCL based on the intra-operative gap measurements made with the PCL intact.

Orthopaedic Proceedings, Feb 21, 2018

Background Pre-operative autologous blood donation is recommended as a means of reducing the need... more Background Pre-operative autologous blood donation is recommended as a means of reducing the need for allogeneic transfusion before simultaneous bilateral total hip arthroplasty (THA). However, there have been few reports on the optimal amount of autologous donation for this procedure. In this study we sought to determine the amount of autologous blood required for patient undergoing simultaneous bilateral THA using the direct anterior approach. Methods We retrospectively enrolled 325 consecutive patients (650 hips) underwent simultaneous bilateral primary THA from January 2012 to June 2014. Thirty-three patients were men and 290 patients were women. The patients’ mean age at THA was 59.1 years. All THAs were performed using the direct anterior approach. Intraoperative blood salvage was applied for all patients and postoperative blood salvage was not applied for any patients. Results The mean intraoperative blood loss and the mean operative time for the bilateral procedure were 413±165 g and 87.2±12.3 minutes, respectively. Two hundreds and forty-one of the 325 patients (74.2%) donated an average of 1.9 (range, 1–2) units of autologous blood before the operation. The mean hemoglobin levels on the preoperative day, postoperative day 1 and postoperative day 5 were 12.5g/dl, 10.5 g/dl and 9.5 g/dl, respectively. Only 1 patient (0.3%) required postoperative transfusions of allogeneic blood. All of the autologous units collected were transfused, and no units were wasted. Conclusion Simultaneous bilateral THA can be performed without allogenic blood transfusion in 99.7% of patients. We could not find out significant effectiveness of an average of 1.9 units of autologous blood donation for this procedure in this study. We concluded that simultaneous bilateral THA can be performed without autologous blood donation in healthy patients without severe hip deformity. Whereas, preoperative donation of autologous blood might be suitable for patients with low body weight or patients with severe hip deformity. The minimally invasive aspect of the direct anterior approach seems to allow a low rate of allogeneic blood transfusion in the study.

Journal of Bone and Joint Surgery-british Volume, Dec 1, 2013

Objective: Accurate measurement of the extension and flexion gap is important in total knee arthr... more Objective: Accurate measurement of the extension and flexion gap is important in total knee arthroplasty (TKA). Particularly, the flexion gap may be influenced by several factors; therefore, tension of the posterior cruciate ligament (PCL), knee extensor mechanism, and the thigh weight may need to be considered while estimating the flexion gap. However, there is no comprehensive study on the flexion gap, including an assessment of the influence of gravity on the gap. The purpose of this study is to investigate the influence of PCL, knee extensor mechanism, and thigh weight on the flexion gap by using a fresh frozen cadaver. Methods: A fresh frozen lower limb that included the pelvis was used for the assessments. The knee was resected by a measured resection technique and a femoral component was implanted to estimate the component gap. The knee was flexed by precisely 90 degrees using a computer navigation system. The flexion gap was measured in different situations: group A, PCL preserved and patella reduced; group B, PCL preserved and patella everted; group C, PCL resected and patella reduced; and group D, PCL resected and patella everted. In each group, the measurements were obtained under 3 different conditions: 1, knee flexed and the lower limb on the operation table under gravity, as is usually done in TKA; 2, hip and knee flexed 90 degrees to avoid the influence of gravity; and 3, knee set in the same position as in condition 1 and the thigh was held by hand to reduce the influence of the thigh weight. Results: The flexion gap differed according to groups and conditions. Group B was larger than group A in most conditions and group D was larger than group C. The flexion gap in group D was the largest among the 4 groups. The extensor mechanism had influences to the flexion gap (Table 1). In groups A and B, the flexion gaps were similar under conditions 1, 2, and 3; however, in groups C and D, the flexion gaps in condition 1 were smaller than those in conditions 2 and 3. The thigh weight condition had influences to the flexion gap when the PCL was resected (Table 2). Conclusion: This is the first systemic report about the influences of PCL, extensor mechanism, and thigh weight on flexion gap measurement in TKA. PCL, extensor mechanism, and thigh weight influence the flexion gap and should be considered during TKA surgery. Especially, careful consideration is necessary to estimate the flexion gap when the PCL is resected and the patella is everted because the flexion gap becomes much wider than other situations.

Journal of Bone and Joint Surgery-british Volume, 2016

Introduction Incorrect restoration of the joint line during total knee arthroplasty (TKA) can res... more Introduction Incorrect restoration of the joint line during total knee arthroplasty (TKA) can result in joint instability, anterior knee pain, limited range of motion, and joint stiffness. Although restoration of the correct joint line (i.e., creating an optimal gap in extension and flexion) should be considered in all TKA procedures, no surgical techniques have been established for restoring it. We performed the femoral posterior condylar precut technique (Kaneyama R. Bone Joint Res. 2014; 3) in 91 TKA cases and evaluated the joint line by measuring the thickness of the surgically removed femoral bone and femoral components. Methods A total of 91 knees in 73 patients who underwent primary TKA between June and December 2013 were reviewed retrospectively. The posterior cruciate ligament was preserved in all patients. First, in the femoral posterior condylar precut technique, the extension gap was created by the measured resection technique. Then we created a temporary gap in flexion 4 mm smaller than that created by the measured resection technique and remove posterior osteophytes and soft tissue for good ligament balance. Once the component gap was determined, final femoral posterior condyle cutting was performed to create an optimal gap and rotation. We evaluated the joint line from the differences in thickness between the surgically removed femoral bone and femoral components, and revised the thickness of the bone saw accordingly. The value was positive when the joint line had been raised and negative when it had been lowered. Results Subjects were 17 men (20 knees) and 56 women (71 knees) with a mean age of 72.6 years. The amount of distal femoral bone surgically removed was 8.5±1.8 mm (medial) and 8.3±2.0 mm (lateral) and that of posterior bone was 9.8±1.2 mm (medial) and 7.2±0.8 mm (lateral). The difference in the joint line was −0.4±2.2 mm (medial) and 0.5±3.9 mm (lateral) in extension and 1.1±2.7 mm (medial) and −0.6±1.9 mm (lateral) in flexion. Discussion There are no established surgical techniques for restoring the joint line. Typically, surgical procedures are decided preoperatively by considering the amount of femoral bone to be surgically removed and rotation and cannot be changed during the operation if the gap is found to be incorrect. In our femoral posterior condylar precut technique, however, is possible to fine-tune it at the final step in surgery, making it possible to control the surgical removal of femoral bone, thereby reducing differences in the joint line.

Journal of Bone and Joint Surgery-british Volume, Dec 1, 2013

Introduction: Total knee arthroplasty (TKA) should aim to adjust the component gap (CG) differenc... more Introduction: Total knee arthroplasty (TKA) should aim to adjust the component gap (CG) difference between extension and flexion. However, this difference cannot be measured without placement of a femoral component. The bone gap reportedly decreases in extension after component setting. In contrast, it may be possible to use the mean value of the CG difference in several patients to adjust femoral resection amount beforehand. The purpose of this study is to evaluate the technique of adjusting CG difference using the mean values with measured resection technique (MRT) in TKA. Materials and methods: The subjects were 222 knees (40 male knees, 182 female knees; mean age 70.4 years). To adjust the CG difference after estimation, the femoral posterior condylar pre-cut technique was used. Extension gap was created by usual bone resection; 4 mm of the femoral posterior condyle was pre-cut, and after all osteophytes and soft tissues had been treated, a pre-cut trial component (thickness of 8 mm for distal femur and 4 mm for posterior condyle without the anterior portion) was mounted, achieving the same condition as the setting of a femoral component in MRT (Fig. 1). When the posterior cruciate ligament (PCL) could be easily preserved by intraoperative gap assessments, the PCL was preserved (190 knees, 86%). Results: The CG measured intraoperatively were 9.4 ± 2.8 mm (mean ± S.D.) in extension and 12.2 ± 2.8 mm in flexion, and the difference (flexion - extension) was 2.8 ± 2.6 mm. The mean difference was not large but the variation was large (−3 ∼ 11 mm). When the acceptable range of CG difference (flexion - extension) is set at 0 to 3 mm, only 57% of the patients were included within this range; when 2 mm of the distal femur was cut beforehand in all patients considering the mean CG difference of 2.8 mm, 53% of the patients were within the acceptable range and 42% had 3 mm resection (Fig. 2). When the acceptable range was expanded to −2 mm to 3 mm, 64% of the patients were in this range, whereas this figure was 76% with an additional 2 mm resection of the distal femur and 72% with 3 mm resection. Even after expanding the acceptable range for CG difference to 5 mm and adjusting the distal femoral cut, one fourth of the patients were outside of the acceptable range (Fig. 3). Discussion: This study showed that the CG using MRT was larger in flexion by a mean of 2.8 mm; however, the variation was too large to manage by larger femoral distal cut according to the mean difference beforehand. Although the PCL was preserved in 190 knees, it is anticipated that gaps in flexion will enlarge when PCL resection is selected for all patients, which may further increase the gap requiring adjustment. To resolve such issues, we use the femoral pre-cut technique and pre-cut trial components. With this method, we can control the CG as we want by adjustment of final femoral bone resection in each patient.

Journal of Bone and Joint Surgery-british Volume, Mar 1, 2013

Introduction Although, the total knee arthroplasty (TKA) procedure is performed to make the same ... more Introduction Although, the total knee arthroplasty (TKA) procedure is performed to make the same extension gap (EG) and flexion gap (FG) of the knee, it is not clear how the gaps can be created equally. According to earlier reports, the gaps after bone resection (bone gaps) differ from the gaps after the trial component of the femur is set (component gaps), because of the thickness of the posterior condyle of the femoral component and the tension of the posterior capsule. The surgeon can only check the component gaps after completing the bone resection and setting the trial component and it difficult to adjust the gaps even when the acquired component gaps are inadequate. To resolve this problem, we developed a “pre-cut trial component” for use in a pre-cut technique for the femoral posterior condyle (Fig. 1). This specially made trial component allows us to check the component gaps before the final bone resection of the femur. Materials and methods The pre-cut trial component is composed of an 8-mm-thick usual distal part and a 4-mm-thick posterior part of the femoral component, and lacks an anterior part of the femoral component. With this pre-cut trail component, 152 knees were investigated. The EG was made by standard resection of distal femur and proximal tibia. The FG was made by a 4 mm pre-cut from the posterior condylar line of the femoral posterior condyle (Fig. 2). The rotation of the pre-cut line is initially decided by anatomical landmarks. Once all of the osteophytes are removed and the bone gaps are checked, the pre-cut trial component is attached to the femur and the component gaps are estimated with the patella reduction (Fig. 3). In our experiments, these gaps were the same as the component gaps after the usual trial component was set via the measured resection technique. Finally, the femur is completely resected according to the measurements of the component gaps with the pre-cut trial component. Results The bone gaps were 18.4±2.4 (mean ± standard deviation) mm in extension and 16.5±2.7 mm in flexion. From these results, the expected component gaps were 10.8±2.7 (bone gap −8) mm in extension and 12.5±2.7 (bone gap −4) mm in flexion. After the pre-cut trial component was set, the measured component gaps were 9.4±2.8 mm in extension and 12.5±2.8 mm in flexion. The EG became 1.5±1.0 mm smaller than expected, and the change of FG was 0.2±0.5 mm. While no large decrease of EG was noted, the variation was not insubstantial (0∼5 mm). Conclusion The difference between the bone gap and component gap is very important for an adequate EG and FG in the TKA procedure. Yet with the conventional technique, the component gap is impossible to estimate before the final bone resection. If unacceptable results are discovered after the component gaps are estimated, the gaps are difficult to correct. With the technique we present here, the component gaps can be checked before final bone resection and truly precise gap control can be attained.

Orthopaedic Proceedings, Sep 1, 2012

Background Minimally invasive surgery is being widely used in the field of total hip arthroplasty... more Background Minimally invasive surgery is being widely used in the field of total hip arthroplasty (THA). The advantages of the direct anterior approach (DAA), which is used in minimally invasive surgery, include low dislocation rate, quick recovery with less pain, and accuracy of prosthesis placement. However, minimally invasive surgery can result in more complications related to the learning curve. The aim of this study was to evaluate the learning curve of DAA-THA performed by a senior resident. Methods Thirty-three consecutive patients (33 hips) who underwent primary THA were enrolled in this study. All operations were performed by a senior resident using DAA in the supine position without the traction table. The surgeon started using DAA exclusively for all cases of primary THA after being trained in this approach for 6 months. Operative time, intraoperative blood loss, complications, and accuracy of prosthesis placement were investigated. Results The mean intraoperative blood loss was 524 mL (range, 130–1650 m L). The mean operative time was 60 min (range, 41–80 min). Radiographic analysis showed an average acetabular anteversion angle of 17.0±3.3°, abduction angle of 37.8±4.3°, and stem alignment of 0±0.8°. Thirty-two (97%) of 33 cups were placed within the Lewinnek9s safe zone. The overall complication rate was 12% (4 of 33 hips), including 1 proximal femoral fracture (salvaged with circumferential wiring), 1 temporary femoral nerve palsy (completely recovered in 2 weeks), 1 stem subsidence (5 mm), and 1 cup migration. Three of these complications were occurred in the first 10 cases. No revision surgery was required, No postoperative dislocation occurred. Conclusion We investigated the learning curve of DAA-THA performed by a senior resident. We considered the first 10 cases as the learning curve, but concluded that with adequate training this procedure can be performed safely and effectively without increasing the risk of complications.

Journal of Bone and Joint Surgery-british Volume, May 1, 2016

Introduction Bulk bone grafting is commonly used in total hip arthroplasty (THA) for developmenta... more Introduction Bulk bone grafting is commonly used in total hip arthroplasty (THA) for developmental dysplasia. However, it is a technically demanding surgery with several critical issues, including graft resorption, graft collapse, and cup loosening. The purpose of this study is to describe our new bone grafting technique and review the radiographic and clinical results. Patients and Methods We retrospectively reviewed 105 hips in 89 patients who had undergone covered bone grafting (CBG) in total hip arthroplasty for developmental dysplasia. We excluded patients who had any previous surgeries or underwent THA with a femoral shortening osteotomy. According to the Crowe classification, 6 hips were classified as group I, 39 as group II, 40 as group III, and 20 as group IV. Follow-up was at a mean of 4.1 (1 ∼ 6.9) years. The surgery was performed using the direct anterior approach. The acetabulum was reamed as close to the original acetabulum as possible. The pressfit cementless cup was impacted into the original acetabulum. After pressfit fixation of the cup was achieved, several screws were used to reinforce the fixation. Indicating factor for using CBG was a large defect where the acetabular roof angle was more than 45 degrees and the uncovered cup was more than 2 cm (Fig.1). The superior defect of the acetabulum was packed with a sufficient amount of morselized bone using bone dust from the acetabular reamers. Then, the grafted morselized bone was covered with a bone plate from the femoral head. The bone plate was fixed with one screw to compact the morselized bone graft. The patient was allowed to walk bearing full weight immediately after surgery. We measured the height of the hip center from the teardrop line and the pelvic height on anteroposterior roentgenograms of the pelvis and calculated the ratio of the hip center to the pelvic height. We defined the anatomical hip center as the height of the center less than 15 % of the pelvic height, which was nearly equal to 30 mm, because the mean pelvic height was 210 mm. Results The mean height of the hip center was 9.8 (4.1∼18.0) % of the pelvic height and the 101 (96.2%) cups were placed within the anatomical hip center. Radiographically, in all patients, the host-graft interface became distinct and the new cortical bone in the lateral part of the plate bone appeared within 1 year after surgery (Fig.2, 3). We observed no absorption of the plate bone graft and no migration of the cup at the last follow-up. Conclusion CBG technique is simple, because the bone graft is always performed after the pressfit of the cup is achieved. Moreover, patients require no partial weight bearing postoperatively, because the cup is supported by the host bone with the pressfit and additional screws. The CBG technique would be an excellent option for the reconstruction of the acetabulum in patients with severe dysplasia to avoid a high hip center and bulky bone grafting.

Chiba medical journal, Oct 1, 2002

Spine, Dec 1, 2006

Study Design. Prospective consecutive series. Objective. To analyze supine and standing radiograp... more Study Design. Prospective consecutive series. Objective. To analyze supine and standing radiographs and the association of back pain using subjective pain criteria. Summary of Background Data. It has been considered that there is little correlation between the degree of collapse of the vertebral body and the level of pain. In previous studies, however, measurements have only been based on supine radiographs. Although there were 2 authors who reported the results of supine lateral and standing lateral radiographs in patients with thoracolumbar vertebral fractures, as far as we know, there has not been any detailed report concerning the correlation between radiologic findings using supine and standing lateral radiographs and back pain. Methods. We examined 100 consecutively treated patients, prospectively. Back pain and the supine and standing radiographs were assessed 1 month after injury. Changes in vertebral wedging rate (WR) from supine to standing position (⌬WR) was reported by the following equation: ⌬WR ϭ WR(standing) Ϫ WR(supine). Results. The median age of the cohort was 75 years (range, 60-89 years). The median VAS of back pain at supine position, at standing position, and when standing erect was 13, 33, and 41, respectively. The median wedging rate on the supine and standing radiographs were 28% and 37%, respectively (P Ͻ 0.001). There was a significant correlation between ⌬WR and back pain when standing erect (r ϭ 0.79, P Ͻ 0.001). Conclusion. Changes in vertebral wedging rate between supine and standing position and its association with back pain may give a clue to the pathogenesis of pain from osteoporotic thoracolumbar vertebral compression fractures.