Federico Girardi - Academia.edu (original) (raw)

Papers by Federico Girardi

The Journal of the American Academy of Orthopaedic Surgeons

Many approaches are used to repair skeletal defects in reconstructive orthopaedic surgery, and bo... more Many approaches are used to repair skeletal defects in reconstructive orthopaedic surgery, and bone grafting is involved in virtually every procedure. The type of bone graft used depends on the clinical scenario and the anticipated final outcome. Autogenous cancellous bone graft, with its osteogenic, osteoinductive, and osteoconductive properties, remains the standard for grafting. However, the high incidence of morbidity during autogenous graft harvest may make the acquisition of grafts from other sources desirable. The clinical applications for each type of bone graft are dictated by the structure and biochemical properties of the graft. An elegant cellular and molecular cascade follows bone transplantation. Bone graft incorporation within the host, whether autogenous or allogeneic, depends on many factors: type of graft (autogenous versus allogeneic, vascular versus nonvascular), site of transplant, quality of transplanted bone and host bone, host bed preparation, preservation techniques, systemic and local disease, and mechanical properties of the graft.

Journal of Spinal Disorders & Techniques

Objective: Our aim was to study the outcomes and results of surgically treated patients with syno... more Objective: Our aim was to study the outcomes and results of surgically treated patients with synovial cysts of the lumbar spine in our institution.

The Journal of the American Academy of Orthopaedic Surgeons

Recently developed materials that can enhance fusion rates for posterolateral lumbar arthrodesis ... more Recently developed materials that can enhance fusion rates for posterolateral lumbar arthrodesis may be used alone or in combination with autogenous bone grafts. Novel osteopromotive growth factor preparations are currently under scrutiny; these include autogenous growth factor concentrate, bovine bone-derived osteoinductive protein, and recombinant human MP52. Demineralized bone matrix products may enhance or extend grafts. However, few studies, especially prospective randomized clinical trials, have assessed their efficacy, so it is difficult to compare formulations. Ceramics have been evaluated in animal studies and human clinical trials for a variety of applications in spinal surgery. These materials function best as bone graft extenders or as bioactive osteoinductive material carriers in posterolateral lumbar fusions. They have the advantage of variable porosity, low cost, and ease of manufacture. Hydroxyapatite/tricalcium phosphate ceramics have been shown to perform as well as autogenous bone grafts but with fewer complications.

Journal of Spinal Disorders & Techniques

Current methods used to measure total disc replacement (TDR) radiographic range of motion (ROM) h... more Current methods used to measure total disc replacement (TDR) radiographic range of motion (ROM) have not been previously evaluated. Sagittal ROM is measured by determining the change in the Cobb angle of the prosthesis from the flexion to the extension radiographs. Either the metallic endplates or the keels of the TDR prosthesis can be used as radiographic landmarks in measuring ROM. We hypothesized that use of the prosthesis keels as radiographic landmarks, when compared with the use of prosthesis endplates, might lead to more precise measurements of TDR sagittal ROM. Two observers (a fifth-year orthopedics resident and an attending orthopedic spine surgeon) measured the ROM of 51 Prodisc II TDRs on standard flexion and extension lumbar spine radiograph sets. Repeated measurements were made on two occasions using either the keels or the endplates as landmarks. Precision was defined as the mean of the absolute differences between measurements. For observer A, the mean absolute difference between two measurements was 1.4 degrees with the keel method compared with 3.0 degrees with the endplate method (P < 0.001). For observer B, the mean absolute difference between two measurements was 1.8 degrees with the keel method and 3.3 degrees with the endplate method (P < 0.001). When the interobserver differences were examined, the mean absolute difference was 1.8 degrees with the keel method and 3.3 degrees with the endplate method (P < 0.001). Our results show that the use of TDR prosthesis keels as radiographic landmarks, when compared with the use of prosthesis endplates, yields greater precision in ROM measurement. For TDR prostheses with a keel, we recommend using the keel to measure ROM.

Asian Spine Journal, 2015

Level 4 retrospective review. To compare the radiographic and clinical outcomes between posterior... more Level 4 retrospective review. To compare the radiographic and clinical outcomes between posterior lumbar interbody fusion (PLIF) and lateral lumbar interbody fusion (LLIF) with posterior segmental spinal instrumentation (SSI) for degenerative lumbar spondylolisthesis. Both PLIF and LLIF have been performed for degenerative spondylolisthesis with good results, but no study has directly compared these two techniques so far. The electronic medical and radiographic records of 78 matched patients were analyzed. In one group, 39 patients underwent PLIF with SSI at 41 levels (L3-4/L4-5), while in the other group, 39 patients underwent the LLIF procedure at 48 levels (L3-4/L4-5). Radiological outcomes such as restoration of disc height and neuroforaminal height, segmental lumbar lordosis, total lumbar lordosis, incidence of endplate fracture, and subsidence were measured. Perioperative parameters were also recorded in each group. Clinical outcome in both groups was assessed by the short form-12, Oswestry disability index and visual analogue scale scores. The average follow-up period was 16.1 months in the LLIF group and 21 months in the PLIF group. The restoration of disc height, foraminal height, and segmental lumbar lordosis was significantly better in the LLIF group (p<0.001). The duration of the operation was similar in both groups, but the average blood loss was significantly lower in the LLIF group (p<0.001). However, clinical outcome scores were similar in both groups. Safe, effective interbody fusion can be achieved at multiple levels with neuromonitoring by the lateral approach. LLIF is a viable treatment option in patients with new onset symptoms due to degenerative spondylolisthesis who have had previous lumbar spine surgery, and it results in improved sagittal alignment and indirect foraminal decompression.

The Spine Journal, 2015

Intraoperative cultures and Gram stains are often obtained in cases of revision spine surgery eve... more Intraoperative cultures and Gram stains are often obtained in cases of revision spine surgery even when clinical signs of infection are not present. The clinical utility and cost-effectiveness of this behavior remain unproven. The aim was to evaluate the clinical utility and cost-effectiveness of routine intraoperative Gram stains in revision spine surgery. This was a retrospective clinical review performed at an academic center in an urban setting. One hundred twenty-nine consecutive adult revision spine surgeries were performed. The outcome measures included intraoperative Gram stains. We retrospectively reviewed the records of 594 consecutive revision spine surgeries performed by four senior surgeons between 2008 and 2013 to identify patients who had operative cultures and Gram stains performed. All revision cases including cervical, thoracic, and lumbar fusion and non-fusion, with and without instrumentation were reviewed. One hundred twenty-nine (21.7%) patients had operative cultures obtained and were included in the study. The most common primary diagnosis code at the time of revision surgery was pseudarthrosis, which was present in 41.9% of cases (54 of 129). Infection was the primary diagnosis in 10.1% (13 of 129) of cases. Operative cultures were obtained in 129 of 595 (21.7%) cases, and 47.3% (61 of 129) were positive. Gram stains were performed in 98 of 129 (76.0%) cases and were positive in 5 of 98 (5.1%) cases. Overall, there was no correlation between revision diagnosis and whether or not a Gram stain was obtained (p=.697). Patients with a history of prior instrumentation were more likely to have a positive Gram stain (p<.0444). Intraoperative Gram staining was found to have a sensitivity of 10.9% (confidence interval [CI] 3.9%-23.6%) and specificity of 100% (CI 93.1%-100%). The positive and negative predictive values were 100% (CI 48.0%-100%) and 57.3% (CI 45.2%-66.2%), respectively. Kappa coefficient was calculated to be 0.1172 (CI 0.0194-0.2151). The cost per discrepant diagnosis (total cost/number discrepant) was $172.10. This study demonstrates that while very specific for infection, the sensitivity of intraoperative Gram staining is low, and agreement between positive cultures and Gram stains is very poor. Gram staining demonstrated limited cost-effectiveness because of the low prevalence of findings that altered patient management.

The bone & joint journal, 2013

The purpose of this study was to investigate the clinical predictors of surgical outcome in patie... more The purpose of this study was to investigate the clinical predictors of surgical outcome in patients with cervical spondylotic myelopathy (CSM). We reviewed a consecutive series of 248 patients (71 women and 177 men) with CSM who had undergone surgery at our institution between January 2000 and October 2010. Their mean age was 59.0 years (16 to 86). Medical records, office notes, and operative reports were reviewed for data collection. Special attention was focused on pre-operative duration and severity as well as post-operative persistence of myelopathic symptoms. Disease severity was graded according to the Nurick classification. Our multivariate logistic regression model indicated that Nurick grade 2 CSM patients have the highest chance of complete symptom resolution (p < 0.001) and improvement to normal gait (p = 0.004) following surgery. Patients who did not improve after surgery had longer duration of myelopathic symptoms than those who did improve post-operatively (17.85 m...

Orthopedics, 2003

Allograft bone extenders are commonly used in spinal surgery to increase the available graft volu... more Allograft bone extenders are commonly used in spinal surgery to increase the available graft volume, thereby promoting and achieving a solid fusion mass. We report a single surgeon's use and early results of autologous bone graft and allograft demineralized bone matrix in 65 patients undergoing lumbar spinal fusion. Of the patients included in this study, 59 (91%) patients underwent surgical intervention for lumbar spinal stenosis, three (5%) patients had lumbar spondylolisthesis, two (3%) patients had stenosis, and one (1%) patient had bilateral spondylolysis. Forty-three (64%) women and 22 (36%) men were included in the study. The average patient age was 56 years (20-85 years, SD= +/- 16). Independent radiographic evaluation was performed. Each subsequent radiographic follow-up revealed increased improvement in average Lenke score and was statistically significant between the early (1 month) and recent (12 month) follow-ups. There were statistically significant changes in Lenk...

American journal of orthopedics (Belle Mead, N.J.), 2014

Because the spine and pelvis are integrated, changes in spine sagittal balance affect relative ac... more Because the spine and pelvis are integrated, changes in spine sagittal balance affect relative acetabulum position. A 1° change of the anterior pelvic plane changes acetabulum anteversion by 0.8°. Three-column spine osteotomies correct fixed sagittal plane deformity. Twenty patients with kyphotic deformity and associated sagittal imbalance underwent corrective 3-column osteotomy. We reviewed upright pelvic and spine radiographs preoperatively and postoperatively and documented the changes in angles. The average sagittal vertical axis was 11.07 cm preoperatively and 4.8 cm postoperatively. Lumbar lordosis changed (on average) from 39° preoperatively to 55° postoperatively (P < .05). Sacral slope increased an average of 6.7° (P = .015). Pelvic tilt decreased by 5.4° (P = .001). The anterior pelvic plane increased by 8.23° (P < .0001). This correction of the sagittal balance is associated with a concomitant increase in sacral slope, pelvic tilt, and the anterior pelvic plane angl...

Advances in Orthopedics, 2012

Low back pain as a result of degenerative disc disease imparts a large socioeconomic impact on th... more Low back pain as a result of degenerative disc disease imparts a large socioeconomic impact on the health care system. Traditional concepts for treatment of lumbar disc degeneration have aimed at symptomatic relief by limiting motion in the lumbar spine, but novel treatment strategies involving stem cells, growth factors, and gene therapy have the theoretical potential to prevent, slow, or even reverse disc degeneration. Understanding the pathophysiological basis of disc degeneration is essential for the development of treatment strategies that target the underlying mechanisms of disc degeneration rather than the downstream symptom of pain. Such strategies ideally aim to induce disc regeneration or to replace the degenerated disc. However, at present, treatment options for degenerative disc disease remain suboptimal, and development and outcomes of novel treatment options currently have to be considered unpredictable.

HSS Journal, 2007

Low-back pain is a common, disabling medical condition, and one of the major causes is disc degen... more Low-back pain is a common, disabling medical condition, and one of the major causes is disc degeneration. Total disc replacements are intended to treat back pain by restoring disc height and re-establishing functional motion and stability at the index level. The objective of this study was to determine the effect on range of motion (ROM) and stiffness after implantation of the ProDisc \ -L device in comparison to the intact state. Twelve L5-S1 lumbar spine segments were tested in flexion/extension, lateral bending, and axial rotation with axial compressive loads of 600 N and 1,200 N. Specimens were tested in the intact state and after implantation with the ProDisc \ -L device. ROM was not significantly different in the implanted spines when compared to their intact state in flexion/extension and axial rotation but increased in lateral bending. Increased compressive load did not affect ROM in flexion/extension or axial rotation but did result in decreased ROM in lateral bending and increased stiffness in both intact and implanted spine segments. The ProDisc \ -L successfully restored or maintained normal spine segment motion.

Orthopedics, 2008

The intravertebral vacuum phenomenon was first described by Kümmel and is also known as delayed v... more The intravertebral vacuum phenomenon was first described by Kümmel and is also known as delayed vertebral collapse or vertebral pseudarthrosis. Clinically, it occurs in approximately 10% of vertebral osteoporotic fractures, mainly in the thoracolumbar zone, is accentuated on extension views and associated with benign fractures. Most patients are neurologically intact, and continued pain is a common symptom that responds well to stabilization. Various theories exist in the literature about the pathogenesis; data support a combination of ischemia and psuedarthrosis. The ultimate treatment plan must be individualized and involve decompression of neurologic elements--when present--and sufficient stabilization, which varies according to surgeon preference and the patient&amp;amp;amp;amp;amp;amp;amp;amp;#39;s combordities.

Techniques in Orthopaedics, 2012

ABSTRACT Degenerative disk disease, lumbar spondylosis, spondylolisthesis, lumbosacral instabilit... more ABSTRACT Degenerative disk disease, lumbar spondylosis, spondylolisthesis, lumbosacral instability, or symptomatic pseudoarthrosis may make interbody fusion a desirable surgical option at the L5-S1 motion segment. Interbody fusion at the lumbosacral junction has conventionally been performed by anterior lumbar interbody fusion or posterior techniques: posterior lumbar interbody fusion or transforaminal lumbar interbody fusion. Earlier spinal surgery or unfavorable lumbosacral anatomy may make certain patients poor candidates for anterior lumbar interbody fusion, posterior lumbar interbody fusion, or transforaminal lumbar interbody fusion. Here, we describe a novel technique for interbody fusion at the L5-S1 segment through a posterior transacral transvertebral reamed approach.

The Spine Journal, 2013

Fractures of the sacrum are a rare complication following instrumented spinal fusion, with only 3... more Fractures of the sacrum are a rare complication following instrumented spinal fusion, with only 34 cases previously reported in the literature. Previous series have generally been limited to less than five cases. The purpose of this study is to determine the incidence of sacral fractures caudal to instrumented spinal fusion constructs, identify risk factors for fracture and for failure of conservative management, and describe strategies for surgical treatment of these fractures. This is a retrospective review. Patients undergoing instrumented posterior spinal arthrodesis between 2002 and 2011 were included in the sample. Clinical and radiographic data from hospital and surgeon records comprise outcome measures. Methods include a review of clinical and radiographic data from a prospectively collected patient database recording all adjacent segment fractures during the study period. Twenty-four patients developed sacral fractures caudal to instrumented spinal fusion constructs during the study period. The overall incidence was 6.1% and was significantly greater in fusions greater than four levels (14.5%). The mean time from index surgery to fracture was 4.3 months. Only one fracture was evident on plain radiography at the onset of symptoms. Computed tomography, magnetic resonance imaging, and nuclear scintigraphy can all be used to establish the diagnosis. Eight patients were successfully treated conservatively. The mean time to fracture union was 21 weeks. Anterolisthesis of the fracture greater than 2 mm and kyphotic angulation were significantly associated with failure of conservative management. Surgical intervention included posterior extension of the fusion construct to S2 and the iliac wings with sacroiliac joint fusion. In 10 cases, a combined anterior and posterior approach was used that consisted of either revision anterior lumbar interbody fusion or transsacral posterior lumbar interbody fusion. Sacral fractures following instrumented posterior spinal fusion are an uncommon complication; that is often unrecognized on plain radiographs. Risk factors include osteoporosis and long spinal fusions. Anterolisthesis and kyphosis of the fracture is associated with failure of conservative management.

Spine, 2014

Retrospective cohort study. To assess the association between vertebral body Hounsfield unit (HU)... more Retrospective cohort study. To assess the association between vertebral body Hounsfield unit (HU) measurements on quantitative computed tomography and the risk for incidental durotomy (ID). ID during spine surgery has been associated with adverse postoperative sequelae that may require prolonged hospital stay and reoperation. Previously identified independent risk factors include age, revision surgery, and lumbar surgery. ID was prospectively documented in spine surgery patients at a single institution during a 2-year period (incidence: 4%, 191/4,822). Patients with ID were matched 1:1 to a control cohort without ID based on age and sex. Inclusion criteria for both cohorts were primary lumbar surgery and quantitative computed tomographic scans within 1 year of date of surgery. Demographic, radiographical, and intraoperative data, along with dual x-ray absorptiometry t scores, were collected and analyzed. A total of 71 patients with ID met the inclusion criteria (38 male, 33 female). Average age of patients with ID was 63.8 ± 12.9 years (range: 34-85 yr). Computed tomographic scans were acquired 1.5 ± 2.2 months away from date of surgery (range: 0-12 mo). Inter-rater reliability for HU measurements between a fellowship-trained spine surgeon and a research fellow was strong (r = 0.901, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). HU values were significantly lower in patients with ID than controls (149.2 ± 60.7 [range: 44.5-301.5] versus 177.0 ± 81.4, [range: 62.0-524.0], respectively; P = 0.023). The area under the receiver operating characteristic curve was 0.603 (P = 0.034). A threshold of 169 HU optimized sensitivity (0.718) and specificity (0.451), and patients with HU value 169 or less were found to be at increased risk for ID (odds ratio: 2.092, 95% confidence interval: 1.042-4.201, P = 0.037). Lower HU value is an accessible clinical marker for increased risk of ID. A threshold value of HU was defined (≤169) that may be used clinically to identify patients at elevated risk for ID, which may improve the informed decision making process prior to spinal surgery. 3.

Journal of Spinal Disorders, 2000

Provocative discography is a controversial diagnostic tool for pathologic discs. Modic has identi... more Provocative discography is a controversial diagnostic tool for pathologic discs. Modic has identified vertebral endplate signal changes on magnetic resonance imaging (MRI) that are thought to signify advanced discogenic degeneration. These two distinct diagnostic tools are examined to determine if there is association between them. Fifty-three consecutive patients who underwent both investigations were retrospectively reviewed. In discs that had negative T1 MRI findings, 28.2% of patients had concordant pain and 17.3% had discordant pain. In discs with positive T1 MRI findings, 34.8% of patients had concordant pain and 17.4% had discordant pain. 79.5% and 74.4% of levels with patient concordant pain on discography had no endplate changes on T1- and T2 weighted MR images, respectively (compared with 84.5% and 81.7%, respectively, for levels with no patient pain on discography). Our data showed no significant relationship between these distinct diagnostic tools. Further investigation of their relative roles in this application is recommended.

HSS Journal ®, 2013

Significance of the thrombophilic abnormalities in development of venous thromboembolism (VTE) ha... more Significance of the thrombophilic abnormalities in development of venous thromboembolism (VTE) has been studies with total hip arthroplasty and acute traumatic spinal cord injury. However, their role as risk factors for VTE in elective spinal surgery remains to be determined. To determine the role of thrombophilic abnormalities in the development of pulmonary embolism (PE) following elective spine surgery. Case and control groups were created in patients who had undergone elective spinal surgery for degenerative conditions. The PE group comprised 12 patients whose post-operative course was complicated by development of PE. The control group included 12 patients with an uneventful post-operative course. Demographic data including age, gender and surgical procedures were matched between the PE group and the control group. Both groups were evaluated for thrombophilic and hypofibrinolytic risk factors at 3 months post-operatively or later. Blood tests were performed to measure fasting serum homocysteine, antithrombin III, and protein C. Molecular genetic testing was conducted for detection of the plasminogen activator inhibitor-1 4G/4G, and prothrombin 3 UTR gene mutations. Heterozygous mutation (G20201A) of prothrombin was detected in two patients (16.7%) in the PE group, whereas no such mutation was noted in the control group. Plasminogen activator inhibitor-1 4G/4G homozygous mutation was seen in three in the PE group and two in the control group. Of homocysteine, antithrombin III and protein C, only one patient in each group showed abnormal levels of homocysteine. In total, there half of the patients in the PE group had at least one thrombophilic abnormality, whereas three (25%) patients showed such abnormality in the control group. These findings suggest the involvement of thrombophilic abnormalities, especially the heterozygous G20201A mutation, in the development of PE in patients undergoing elective spinal surgery.

Evidence-Based Spine-Care Journal, 2014

Design Retrospective case series. Objective The objective of this study was to assess the reopera... more Design Retrospective case series. Objective The objective of this study was to assess the reoperation rate after microdiscectomy for the treatment of lumbar disc herniation (LDH) in patients with ≥ 5-year follow-up and identify demographic, perioperative, and outcome-related differences between patients with and without a reoperation. Methods The medical records, operative reports, and office notes of patients who had undergone microdiscectomy at a single institution between March 1994 and December 2007 were reviewed and long-term follow-up was assessed via a telephone questionnaire. Results Forty patients (M:24, F:16) with an average age at surgery of 39.9 ± 12.5 years (range: 18-80) underwent microdiscectomy at the levels L5-S1 (n = 28, 70%), L4-L5 (n = 9, 22.5%), L3-L4 (n = 2, 5.0%), and L1-L2 (n = 1, 2.5%). After an average of 40.4 ± 40.1 months (range: 1-128), 25% of patients (10/40) required further spine surgery related to the initial microdiscectomy. At an average postoperative follow-up of 11.1 ± 4.0 years (range: 5-19), additional symptoms apart from back and leg pain were reported more frequently by patients who underwent a reoperation (p = 0.005). Patient satisfaction was significantly higher in patients who did not undergo a reoperation (p = 0.041). For the Oswestry disability index, pain intensity (p = 0.036), and pain-related sleep disturbances (p = 0.006) were reported to be more severe in the reoperation group. Conclusions Microdiscectomy for the treatment of LDH results in a favorable long-term outcome in the majority of cases. The reoperation rate was higher in our series than reported in previous investigations with shorter follow-up. Although there were no statistically significant pre-/perioperative differences between patients with and without reoperation, our findings suggest a difference in self-reported long-term outcome measures.

The Journal of the American Academy of Orthopaedic Surgeons

Many approaches are used to repair skeletal defects in reconstructive orthopaedic surgery, and bo... more Many approaches are used to repair skeletal defects in reconstructive orthopaedic surgery, and bone grafting is involved in virtually every procedure. The type of bone graft used depends on the clinical scenario and the anticipated final outcome. Autogenous cancellous bone graft, with its osteogenic, osteoinductive, and osteoconductive properties, remains the standard for grafting. However, the high incidence of morbidity during autogenous graft harvest may make the acquisition of grafts from other sources desirable. The clinical applications for each type of bone graft are dictated by the structure and biochemical properties of the graft. An elegant cellular and molecular cascade follows bone transplantation. Bone graft incorporation within the host, whether autogenous or allogeneic, depends on many factors: type of graft (autogenous versus allogeneic, vascular versus nonvascular), site of transplant, quality of transplanted bone and host bone, host bed preparation, preservation techniques, systemic and local disease, and mechanical properties of the graft.

Journal of Spinal Disorders & Techniques

Objective: Our aim was to study the outcomes and results of surgically treated patients with syno... more Objective: Our aim was to study the outcomes and results of surgically treated patients with synovial cysts of the lumbar spine in our institution.

The Journal of the American Academy of Orthopaedic Surgeons

Recently developed materials that can enhance fusion rates for posterolateral lumbar arthrodesis ... more Recently developed materials that can enhance fusion rates for posterolateral lumbar arthrodesis may be used alone or in combination with autogenous bone grafts. Novel osteopromotive growth factor preparations are currently under scrutiny; these include autogenous growth factor concentrate, bovine bone-derived osteoinductive protein, and recombinant human MP52. Demineralized bone matrix products may enhance or extend grafts. However, few studies, especially prospective randomized clinical trials, have assessed their efficacy, so it is difficult to compare formulations. Ceramics have been evaluated in animal studies and human clinical trials for a variety of applications in spinal surgery. These materials function best as bone graft extenders or as bioactive osteoinductive material carriers in posterolateral lumbar fusions. They have the advantage of variable porosity, low cost, and ease of manufacture. Hydroxyapatite/tricalcium phosphate ceramics have been shown to perform as well as autogenous bone grafts but with fewer complications.

Journal of Spinal Disorders & Techniques

Current methods used to measure total disc replacement (TDR) radiographic range of motion (ROM) h... more Current methods used to measure total disc replacement (TDR) radiographic range of motion (ROM) have not been previously evaluated. Sagittal ROM is measured by determining the change in the Cobb angle of the prosthesis from the flexion to the extension radiographs. Either the metallic endplates or the keels of the TDR prosthesis can be used as radiographic landmarks in measuring ROM. We hypothesized that use of the prosthesis keels as radiographic landmarks, when compared with the use of prosthesis endplates, might lead to more precise measurements of TDR sagittal ROM. Two observers (a fifth-year orthopedics resident and an attending orthopedic spine surgeon) measured the ROM of 51 Prodisc II TDRs on standard flexion and extension lumbar spine radiograph sets. Repeated measurements were made on two occasions using either the keels or the endplates as landmarks. Precision was defined as the mean of the absolute differences between measurements. For observer A, the mean absolute difference between two measurements was 1.4 degrees with the keel method compared with 3.0 degrees with the endplate method (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). For observer B, the mean absolute difference between two measurements was 1.8 degrees with the keel method and 3.3 degrees with the endplate method (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). When the interobserver differences were examined, the mean absolute difference was 1.8 degrees with the keel method and 3.3 degrees with the endplate method (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Our results show that the use of TDR prosthesis keels as radiographic landmarks, when compared with the use of prosthesis endplates, yields greater precision in ROM measurement. For TDR prostheses with a keel, we recommend using the keel to measure ROM.

Asian Spine Journal, 2015

Level 4 retrospective review. To compare the radiographic and clinical outcomes between posterior... more Level 4 retrospective review. To compare the radiographic and clinical outcomes between posterior lumbar interbody fusion (PLIF) and lateral lumbar interbody fusion (LLIF) with posterior segmental spinal instrumentation (SSI) for degenerative lumbar spondylolisthesis. Both PLIF and LLIF have been performed for degenerative spondylolisthesis with good results, but no study has directly compared these two techniques so far. The electronic medical and radiographic records of 78 matched patients were analyzed. In one group, 39 patients underwent PLIF with SSI at 41 levels (L3-4/L4-5), while in the other group, 39 patients underwent the LLIF procedure at 48 levels (L3-4/L4-5). Radiological outcomes such as restoration of disc height and neuroforaminal height, segmental lumbar lordosis, total lumbar lordosis, incidence of endplate fracture, and subsidence were measured. Perioperative parameters were also recorded in each group. Clinical outcome in both groups was assessed by the short form-12, Oswestry disability index and visual analogue scale scores. The average follow-up period was 16.1 months in the LLIF group and 21 months in the PLIF group. The restoration of disc height, foraminal height, and segmental lumbar lordosis was significantly better in the LLIF group (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). The duration of the operation was similar in both groups, but the average blood loss was significantly lower in the LLIF group (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). However, clinical outcome scores were similar in both groups. Safe, effective interbody fusion can be achieved at multiple levels with neuromonitoring by the lateral approach. LLIF is a viable treatment option in patients with new onset symptoms due to degenerative spondylolisthesis who have had previous lumbar spine surgery, and it results in improved sagittal alignment and indirect foraminal decompression.

The Spine Journal, 2015

Intraoperative cultures and Gram stains are often obtained in cases of revision spine surgery eve... more Intraoperative cultures and Gram stains are often obtained in cases of revision spine surgery even when clinical signs of infection are not present. The clinical utility and cost-effectiveness of this behavior remain unproven. The aim was to evaluate the clinical utility and cost-effectiveness of routine intraoperative Gram stains in revision spine surgery. This was a retrospective clinical review performed at an academic center in an urban setting. One hundred twenty-nine consecutive adult revision spine surgeries were performed. The outcome measures included intraoperative Gram stains. We retrospectively reviewed the records of 594 consecutive revision spine surgeries performed by four senior surgeons between 2008 and 2013 to identify patients who had operative cultures and Gram stains performed. All revision cases including cervical, thoracic, and lumbar fusion and non-fusion, with and without instrumentation were reviewed. One hundred twenty-nine (21.7%) patients had operative cultures obtained and were included in the study. The most common primary diagnosis code at the time of revision surgery was pseudarthrosis, which was present in 41.9% of cases (54 of 129). Infection was the primary diagnosis in 10.1% (13 of 129) of cases. Operative cultures were obtained in 129 of 595 (21.7%) cases, and 47.3% (61 of 129) were positive. Gram stains were performed in 98 of 129 (76.0%) cases and were positive in 5 of 98 (5.1%) cases. Overall, there was no correlation between revision diagnosis and whether or not a Gram stain was obtained (p=.697). Patients with a history of prior instrumentation were more likely to have a positive Gram stain (p&amp;amp;amp;amp;amp;amp;lt;.0444). Intraoperative Gram staining was found to have a sensitivity of 10.9% (confidence interval [CI] 3.9%-23.6%) and specificity of 100% (CI 93.1%-100%). The positive and negative predictive values were 100% (CI 48.0%-100%) and 57.3% (CI 45.2%-66.2%), respectively. Kappa coefficient was calculated to be 0.1172 (CI 0.0194-0.2151). The cost per discrepant diagnosis (total cost/number discrepant) was $172.10. This study demonstrates that while very specific for infection, the sensitivity of intraoperative Gram staining is low, and agreement between positive cultures and Gram stains is very poor. Gram staining demonstrated limited cost-effectiveness because of the low prevalence of findings that altered patient management.

The bone & joint journal, 2013

The purpose of this study was to investigate the clinical predictors of surgical outcome in patie... more The purpose of this study was to investigate the clinical predictors of surgical outcome in patients with cervical spondylotic myelopathy (CSM). We reviewed a consecutive series of 248 patients (71 women and 177 men) with CSM who had undergone surgery at our institution between January 2000 and October 2010. Their mean age was 59.0 years (16 to 86). Medical records, office notes, and operative reports were reviewed for data collection. Special attention was focused on pre-operative duration and severity as well as post-operative persistence of myelopathic symptoms. Disease severity was graded according to the Nurick classification. Our multivariate logistic regression model indicated that Nurick grade 2 CSM patients have the highest chance of complete symptom resolution (p < 0.001) and improvement to normal gait (p = 0.004) following surgery. Patients who did not improve after surgery had longer duration of myelopathic symptoms than those who did improve post-operatively (17.85 m...

Orthopedics, 2003

Allograft bone extenders are commonly used in spinal surgery to increase the available graft volu... more Allograft bone extenders are commonly used in spinal surgery to increase the available graft volume, thereby promoting and achieving a solid fusion mass. We report a single surgeon's use and early results of autologous bone graft and allograft demineralized bone matrix in 65 patients undergoing lumbar spinal fusion. Of the patients included in this study, 59 (91%) patients underwent surgical intervention for lumbar spinal stenosis, three (5%) patients had lumbar spondylolisthesis, two (3%) patients had stenosis, and one (1%) patient had bilateral spondylolysis. Forty-three (64%) women and 22 (36%) men were included in the study. The average patient age was 56 years (20-85 years, SD= +/- 16). Independent radiographic evaluation was performed. Each subsequent radiographic follow-up revealed increased improvement in average Lenke score and was statistically significant between the early (1 month) and recent (12 month) follow-ups. There were statistically significant changes in Lenk...

American journal of orthopedics (Belle Mead, N.J.), 2014

Because the spine and pelvis are integrated, changes in spine sagittal balance affect relative ac... more Because the spine and pelvis are integrated, changes in spine sagittal balance affect relative acetabulum position. A 1° change of the anterior pelvic plane changes acetabulum anteversion by 0.8°. Three-column spine osteotomies correct fixed sagittal plane deformity. Twenty patients with kyphotic deformity and associated sagittal imbalance underwent corrective 3-column osteotomy. We reviewed upright pelvic and spine radiographs preoperatively and postoperatively and documented the changes in angles. The average sagittal vertical axis was 11.07 cm preoperatively and 4.8 cm postoperatively. Lumbar lordosis changed (on average) from 39° preoperatively to 55° postoperatively (P < .05). Sacral slope increased an average of 6.7° (P = .015). Pelvic tilt decreased by 5.4° (P = .001). The anterior pelvic plane increased by 8.23° (P < .0001). This correction of the sagittal balance is associated with a concomitant increase in sacral slope, pelvic tilt, and the anterior pelvic plane angl...

Advances in Orthopedics, 2012

Low back pain as a result of degenerative disc disease imparts a large socioeconomic impact on th... more Low back pain as a result of degenerative disc disease imparts a large socioeconomic impact on the health care system. Traditional concepts for treatment of lumbar disc degeneration have aimed at symptomatic relief by limiting motion in the lumbar spine, but novel treatment strategies involving stem cells, growth factors, and gene therapy have the theoretical potential to prevent, slow, or even reverse disc degeneration. Understanding the pathophysiological basis of disc degeneration is essential for the development of treatment strategies that target the underlying mechanisms of disc degeneration rather than the downstream symptom of pain. Such strategies ideally aim to induce disc regeneration or to replace the degenerated disc. However, at present, treatment options for degenerative disc disease remain suboptimal, and development and outcomes of novel treatment options currently have to be considered unpredictable.

HSS Journal, 2007

Low-back pain is a common, disabling medical condition, and one of the major causes is disc degen... more Low-back pain is a common, disabling medical condition, and one of the major causes is disc degeneration. Total disc replacements are intended to treat back pain by restoring disc height and re-establishing functional motion and stability at the index level. The objective of this study was to determine the effect on range of motion (ROM) and stiffness after implantation of the ProDisc \ -L device in comparison to the intact state. Twelve L5-S1 lumbar spine segments were tested in flexion/extension, lateral bending, and axial rotation with axial compressive loads of 600 N and 1,200 N. Specimens were tested in the intact state and after implantation with the ProDisc \ -L device. ROM was not significantly different in the implanted spines when compared to their intact state in flexion/extension and axial rotation but increased in lateral bending. Increased compressive load did not affect ROM in flexion/extension or axial rotation but did result in decreased ROM in lateral bending and increased stiffness in both intact and implanted spine segments. The ProDisc \ -L successfully restored or maintained normal spine segment motion.

Orthopedics, 2008

The intravertebral vacuum phenomenon was first described by Kümmel and is also known as delayed v... more The intravertebral vacuum phenomenon was first described by Kümmel and is also known as delayed vertebral collapse or vertebral pseudarthrosis. Clinically, it occurs in approximately 10% of vertebral osteoporotic fractures, mainly in the thoracolumbar zone, is accentuated on extension views and associated with benign fractures. Most patients are neurologically intact, and continued pain is a common symptom that responds well to stabilization. Various theories exist in the literature about the pathogenesis; data support a combination of ischemia and psuedarthrosis. The ultimate treatment plan must be individualized and involve decompression of neurologic elements--when present--and sufficient stabilization, which varies according to surgeon preference and the patient&amp;amp;amp;amp;amp;amp;amp;amp;#39;s combordities.

Techniques in Orthopaedics, 2012

ABSTRACT Degenerative disk disease, lumbar spondylosis, spondylolisthesis, lumbosacral instabilit... more ABSTRACT Degenerative disk disease, lumbar spondylosis, spondylolisthesis, lumbosacral instability, or symptomatic pseudoarthrosis may make interbody fusion a desirable surgical option at the L5-S1 motion segment. Interbody fusion at the lumbosacral junction has conventionally been performed by anterior lumbar interbody fusion or posterior techniques: posterior lumbar interbody fusion or transforaminal lumbar interbody fusion. Earlier spinal surgery or unfavorable lumbosacral anatomy may make certain patients poor candidates for anterior lumbar interbody fusion, posterior lumbar interbody fusion, or transforaminal lumbar interbody fusion. Here, we describe a novel technique for interbody fusion at the L5-S1 segment through a posterior transacral transvertebral reamed approach.

The Spine Journal, 2013

Fractures of the sacrum are a rare complication following instrumented spinal fusion, with only 3... more Fractures of the sacrum are a rare complication following instrumented spinal fusion, with only 34 cases previously reported in the literature. Previous series have generally been limited to less than five cases. The purpose of this study is to determine the incidence of sacral fractures caudal to instrumented spinal fusion constructs, identify risk factors for fracture and for failure of conservative management, and describe strategies for surgical treatment of these fractures. This is a retrospective review. Patients undergoing instrumented posterior spinal arthrodesis between 2002 and 2011 were included in the sample. Clinical and radiographic data from hospital and surgeon records comprise outcome measures. Methods include a review of clinical and radiographic data from a prospectively collected patient database recording all adjacent segment fractures during the study period. Twenty-four patients developed sacral fractures caudal to instrumented spinal fusion constructs during the study period. The overall incidence was 6.1% and was significantly greater in fusions greater than four levels (14.5%). The mean time from index surgery to fracture was 4.3 months. Only one fracture was evident on plain radiography at the onset of symptoms. Computed tomography, magnetic resonance imaging, and nuclear scintigraphy can all be used to establish the diagnosis. Eight patients were successfully treated conservatively. The mean time to fracture union was 21 weeks. Anterolisthesis of the fracture greater than 2 mm and kyphotic angulation were significantly associated with failure of conservative management. Surgical intervention included posterior extension of the fusion construct to S2 and the iliac wings with sacroiliac joint fusion. In 10 cases, a combined anterior and posterior approach was used that consisted of either revision anterior lumbar interbody fusion or transsacral posterior lumbar interbody fusion. Sacral fractures following instrumented posterior spinal fusion are an uncommon complication; that is often unrecognized on plain radiographs. Risk factors include osteoporosis and long spinal fusions. Anterolisthesis and kyphosis of the fracture is associated with failure of conservative management.

Spine, 2014

Retrospective cohort study. To assess the association between vertebral body Hounsfield unit (HU)... more Retrospective cohort study. To assess the association between vertebral body Hounsfield unit (HU) measurements on quantitative computed tomography and the risk for incidental durotomy (ID). ID during spine surgery has been associated with adverse postoperative sequelae that may require prolonged hospital stay and reoperation. Previously identified independent risk factors include age, revision surgery, and lumbar surgery. ID was prospectively documented in spine surgery patients at a single institution during a 2-year period (incidence: 4%, 191/4,822). Patients with ID were matched 1:1 to a control cohort without ID based on age and sex. Inclusion criteria for both cohorts were primary lumbar surgery and quantitative computed tomographic scans within 1 year of date of surgery. Demographic, radiographical, and intraoperative data, along with dual x-ray absorptiometry t scores, were collected and analyzed. A total of 71 patients with ID met the inclusion criteria (38 male, 33 female). Average age of patients with ID was 63.8 ± 12.9 years (range: 34-85 yr). Computed tomographic scans were acquired 1.5 ± 2.2 months away from date of surgery (range: 0-12 mo). Inter-rater reliability for HU measurements between a fellowship-trained spine surgeon and a research fellow was strong (r = 0.901, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). HU values were significantly lower in patients with ID than controls (149.2 ± 60.7 [range: 44.5-301.5] versus 177.0 ± 81.4, [range: 62.0-524.0], respectively; P = 0.023). The area under the receiver operating characteristic curve was 0.603 (P = 0.034). A threshold of 169 HU optimized sensitivity (0.718) and specificity (0.451), and patients with HU value 169 or less were found to be at increased risk for ID (odds ratio: 2.092, 95% confidence interval: 1.042-4.201, P = 0.037). Lower HU value is an accessible clinical marker for increased risk of ID. A threshold value of HU was defined (≤169) that may be used clinically to identify patients at elevated risk for ID, which may improve the informed decision making process prior to spinal surgery. 3.

Journal of Spinal Disorders, 2000

Provocative discography is a controversial diagnostic tool for pathologic discs. Modic has identi... more Provocative discography is a controversial diagnostic tool for pathologic discs. Modic has identified vertebral endplate signal changes on magnetic resonance imaging (MRI) that are thought to signify advanced discogenic degeneration. These two distinct diagnostic tools are examined to determine if there is association between them. Fifty-three consecutive patients who underwent both investigations were retrospectively reviewed. In discs that had negative T1 MRI findings, 28.2% of patients had concordant pain and 17.3% had discordant pain. In discs with positive T1 MRI findings, 34.8% of patients had concordant pain and 17.4% had discordant pain. 79.5% and 74.4% of levels with patient concordant pain on discography had no endplate changes on T1- and T2 weighted MR images, respectively (compared with 84.5% and 81.7%, respectively, for levels with no patient pain on discography). Our data showed no significant relationship between these distinct diagnostic tools. Further investigation of their relative roles in this application is recommended.

HSS Journal ®, 2013

Significance of the thrombophilic abnormalities in development of venous thromboembolism (VTE) ha... more Significance of the thrombophilic abnormalities in development of venous thromboembolism (VTE) has been studies with total hip arthroplasty and acute traumatic spinal cord injury. However, their role as risk factors for VTE in elective spinal surgery remains to be determined. To determine the role of thrombophilic abnormalities in the development of pulmonary embolism (PE) following elective spine surgery. Case and control groups were created in patients who had undergone elective spinal surgery for degenerative conditions. The PE group comprised 12 patients whose post-operative course was complicated by development of PE. The control group included 12 patients with an uneventful post-operative course. Demographic data including age, gender and surgical procedures were matched between the PE group and the control group. Both groups were evaluated for thrombophilic and hypofibrinolytic risk factors at 3 months post-operatively or later. Blood tests were performed to measure fasting serum homocysteine, antithrombin III, and protein C. Molecular genetic testing was conducted for detection of the plasminogen activator inhibitor-1 4G/4G, and prothrombin 3 UTR gene mutations. Heterozygous mutation (G20201A) of prothrombin was detected in two patients (16.7%) in the PE group, whereas no such mutation was noted in the control group. Plasminogen activator inhibitor-1 4G/4G homozygous mutation was seen in three in the PE group and two in the control group. Of homocysteine, antithrombin III and protein C, only one patient in each group showed abnormal levels of homocysteine. In total, there half of the patients in the PE group had at least one thrombophilic abnormality, whereas three (25%) patients showed such abnormality in the control group. These findings suggest the involvement of thrombophilic abnormalities, especially the heterozygous G20201A mutation, in the development of PE in patients undergoing elective spinal surgery.

Evidence-Based Spine-Care Journal, 2014

Design Retrospective case series. Objective The objective of this study was to assess the reopera... more Design Retrospective case series. Objective The objective of this study was to assess the reoperation rate after microdiscectomy for the treatment of lumbar disc herniation (LDH) in patients with ≥ 5-year follow-up and identify demographic, perioperative, and outcome-related differences between patients with and without a reoperation. Methods The medical records, operative reports, and office notes of patients who had undergone microdiscectomy at a single institution between March 1994 and December 2007 were reviewed and long-term follow-up was assessed via a telephone questionnaire. Results Forty patients (M:24, F:16) with an average age at surgery of 39.9 ± 12.5 years (range: 18-80) underwent microdiscectomy at the levels L5-S1 (n = 28, 70%), L4-L5 (n = 9, 22.5%), L3-L4 (n = 2, 5.0%), and L1-L2 (n = 1, 2.5%). After an average of 40.4 ± 40.1 months (range: 1-128), 25% of patients (10/40) required further spine surgery related to the initial microdiscectomy. At an average postoperative follow-up of 11.1 ± 4.0 years (range: 5-19), additional symptoms apart from back and leg pain were reported more frequently by patients who underwent a reoperation (p = 0.005). Patient satisfaction was significantly higher in patients who did not undergo a reoperation (p = 0.041). For the Oswestry disability index, pain intensity (p = 0.036), and pain-related sleep disturbances (p = 0.006) were reported to be more severe in the reoperation group. Conclusions Microdiscectomy for the treatment of LDH results in a favorable long-term outcome in the majority of cases. The reoperation rate was higher in our series than reported in previous investigations with shorter follow-up. Although there were no statistically significant pre-/perioperative differences between patients with and without reoperation, our findings suggest a difference in self-reported long-term outcome measures.