Donald Longjohn - Academia.edu (original) (raw)

Papers by Donald Longjohn

Journal of Arthroplasty, May 1, 2023

Journal of Arthroplasty, Jun 1, 2023

Journal of Arthroplasty, Aug 1, 2022

BACKGROUND Advances in surgical technique and prosthesis design have expanded the non-neoplastic ... more BACKGROUND Advances in surgical technique and prosthesis design have expanded the non-neoplastic indications for proximal femoral replacement (PFR) to include fracture nonunion, periprosthetic fracture, and severe bone loss in the setting of revision total hip arthroplasty (THA). The purpose of this study is to assess outcomes of PFRs used for non-oncologic indications. METHODS A single-institution, retrospective cohort survey study was conducted between August 2015-February 2020 of consecutive patients undergoing PFR for non-oncologic indications in revision THA. Patient demographics, surgical variables, complications, and revision procedures were collected. Patient satisfaction and Oxford Hip scores were assessed via telephone questionnaire. Implant survivorship was estimated using the Kaplan-Meier method. RESULTS In total, 24 patients (27 PFRs) were available for analysis with an average age of 69.3±12.9 years (range: 37-90). The average number of operations prior to PFR implantation was 3.1±2.1 (range: 0-7). At mean follow-up of 2.4 years (range: 0.5-5.1), the mean Oxford Hip Score was 31.7±10.2 and mean patient satisfaction was 4.9/5. Six patients (20.7%) experienced a postoperative complication, with dislocation occurring in three patients (10.3%). None of the patients with dual mobility articulations (n=4) dislocated. Three-year survivorship was 85.2% (95%CI 71.8%-98.6%) with all-cause reoperations as the endpoint and 100% (95%CI 100.0%-100.0%) with revision for aseptic loosening as the endpoint. CONCLUSIONS The current study demonstrates excellent short-term survivorship, satisfactory patient-reported outcomes, and high patient satisfaction following PFR for non-oncologic indications during revision THA utilizing modern techniques. The most common mode of failure was dislocation requiring reoperation with revision to constrained acetabular components.

Current Orthopaedics, Oct 1, 1998

ABSTRACT Distal fixation with extensively porous-coated stems has demonstrated good fixation, but... more ABSTRACT Distal fixation with extensively porous-coated stems has demonstrated good fixation, but a high incidence of proximal stress-shielding. Proximal femoral fixation was developed to load the femur proximally to avoid the problem of stress-shielding. First generation proximal fixation stems had a high percentage of thigh pain and loosening. Second generation designs with mechanical fixation only in the diaphysis (smooth distal stems) improved fixation, but still demonstrated a relatively high incidence of thigh pain. It is now evident that biologic fixation is required in the diaphysis. Still, proximal fixation must occur in the cortical bone of the proximal femur. Stems with a geometry that primarily load the proximal femur, and yet achieve biologic (osseous) fixation in the diaphysis, result in ‘transitional stress transfer’ to the femur. Contemporary designs that employ these principles are successful in providing durable fixation, a low incidence of thigh pain, and avoid the problem of stress-shielding.

PubMed, May 1, 2008

Total joint replacement patients today are younger, heavier, and more active than total joint rep... more Total joint replacement patients today are younger, heavier, and more active than total joint replacement patients 40 yrs ago. Consequently, patient expectations and prosthesis requirements have increased and there is a need to re-evaluate preclinical testing methods. We present the design rationale for a novel load simulator for the proximal femur, capable of applying a more aggressive load profile than previous simulators. This simulator was used to measure three-dimensional micromotion of a cemented total hip replacement femoral stem under simulated physiological loading. We assessed the influence of a separate abductor muscle force, a higher joint reaction force, and a more accurate implant stability measurement system included in the new simulator and compared the results to the lower, single joint reaction force included in a previously published simulator. Per-cycle motion at both cement interfaces and stem and cement mantle migration obtained from both simulators using the same femoral stem design, are compared. Although the new simulator applied higher loads, per-cycle motions were lower than previously reported. In both studies, regardless of the presence or lack of a separate muscle force, the greatest motions were in the medial-lateral direction (new: 27 +/- 4 mum, old: 67 +/- 21 mum). The findings indicate that magnitude and direction of peak joint reaction force and inclusion of a separate muscle force have a significant effect on femoral stem stability measurements. We recommend that future femoral stem stability studies consider using load simulation techniques and a direct motion measurement system comparable to the one presented in this study.

Journal of Biomechanics, 2011

In this study, the in vitro fixation of four otherwise identical double-tapered stem-types, varyi... more In this study, the in vitro fixation of four otherwise identical double-tapered stem-types, varying only in surface finish (polished or matte) and proximal stem geometry (with or without flanges) were compared under two conditions. First, four specimens of each stem type were tested with initially bonded stem-cement interfaces, representing early post-operative conditions. Then, simulating conditions a few weeks to months later, stems were implanted in unused synthetic femurs, with a thin layer coating the stem to prevent stem-cement adhesion. Per-cycle motions were measured at both cement interfaces throughout loading. Overall, surface finish had the smallest relative effect on fixation compared to flanges. Flanges increased axial fixation by 22 μm per-cycle, regardless of surface finish (P=0.01). Further, all stems moved under dynamic load at the stem-cement interface during the first few cycles of loading, even without a thin film. The results indicate that flanges have a greater effect on fixation than surface finish, and therefore adverse findings about matte surfaces should not necessarily apply to all double-tapered stems. Specifically, dorsal flanges enhance the stability of a tapered cemented femoral stem, regardless of surface finish.

Journal of Bone and Joint Surgery, American Volume, Apr 1, 2004

Although current designs of cemented femoral stems for total hip replacement include both those w... more Although current designs of cemented femoral stems for total hip replacement include both those with and those without a flanged shape at the proximal end, the influence of anteroposterior dorsal flanges on the fixation of the stem is not completely understood. The purpose of this study was to assess the effects of flanges on femoral stem stability and load transfer to the femur with use of an in vitro model. We measured femoral surface strains and three-dimensional micromotion in synthetic femora under cyclic loading with four types of stems: those with flanges and those without flanges in two sizes each. The four types of stems were otherwise identical; that is, all of them were straight, polished, and collarless. Stem-cement micromotion measurements and strain measurements were repeated with three stems of each type, whereas bone-cement micromotion measurements were made with one stem of each type. Flanges had a greater influence on femoral strains and micromotion than did the difference in the cement thickness resulting from the different stem sizes. Specifically, the flanged stems produced greater strains on the medial femoral surface but smaller strains on the anterior surface than did the non-flanged stems. Flanged stems achieved tighter mechanical interlock within the cement, but these stems increased bone-cement micromotion. Specifically, the motion per cycle of flanged stems within the cement mantle was smaller than that of non-flanged stems, whereas the motion per cycle of the cement mantle within the femoral canal was greater with the flanged stems than with the non-flanged stems. Flanges on a total hip femoral stem increase the interlock between the stem and the cement and decrease the proximal-medial stress-shielding. However, these advantages occur with increased bone-cement interface motion, which may be detrimental to the survival of the implant.

Hip International, Mar 8, 2016

ORIGInAL RESEARCH ARTICLE more stress shielding, and that larger, noncemented, cobaltchromium (Co... more ORIGInAL RESEARCH ARTICLE more stress shielding, and that larger, noncemented, cobaltchromium (CoCr) stems can lead to thigh pain. Conversely, titanium (Ti) alloy stems transfer more load to the surrounding bone (7-9). Despite the vast amount of literature on the subject, it is difficult to quantitatively assess the relative influences of these differences as a function of stem design characteristics. In order to reduce bone loss, investigators have identified key design features that successfully reduce stress shielding. Specifically, previous studies have found that factors such as stem material, fixation method, and surface features appear to greatly influence changes in periprosthetic bone mineral density (BMD) (10-12). Previous studies have shown that the location of femoral stem fixation onto the bone plays a role in bone remodelling, where shorter stems allow the maintenance of more physiologic load transfers to the proximal femur, thereby decreasing overall bone loss following metaphyseal fixation (13). Additionally, some studies have proposed the use of shorter stems for their less invasive surgical techniques that preserve more native bone stock (14, 15). While previous studies have demonstrated that stem design influences bone remodelling, these studies were limited by the comparisons made between specific implants. Some only observed the bone remodelling patterns of 1 specific stem design against a control rather than comparing 2 unique

Trials, Mar 29, 2023

Background Pain management is a critical component of comprehensive postsurgical care, as it infl... more Background Pain management is a critical component of comprehensive postsurgical care, as it influences patient safety and outcomes, and inadequate control has been associated with the development of chronic pain syndromes. Despite recent improvements, the management of postoperative pain following total knee arthroplasty (TKA) remains a challenge. The use of opioid-sparing, multimodal analgesic regimens has broad support, but there is a paucity of high-quality evidence regarding optimal postoperative protocols and novel approaches are needed. Dextromethorphan stands out among both well-studied and emerging pharmacological adjuncts for postoperative pain due its robust safety profile and unique pharmacology. The purpose of this study is to evaluate the efficacy of multi-dose dextromethorphan for postoperative pain control following TKA. Methods This is a single-center, multi-dose, randomized, double-blinded, placebo-controlled trial. A total of 160 participants will be randomized 1:1 to receive either 60 mg oral dextromethorphan hydrobromide preoperatively, as well as 30 mg 8 h and 16 h postoperatively, or matching placebo. Outcome data will be obtained at baseline, during the first 48 h, and the first two follow-up visits. The primary outcome measure will be total opioid consumption at 24 h postoperatively. Secondary outcomes related to pain, function, and quality of life will be evaluated using standard pain scales, the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) questionnaire, the Patient-Reported Outcomes Measurement Information System (PROMIS-29) questionnaire, and clinical anchors. Discussion This study has a number of strengths including adequate power, a randomized controlled design, and an evidence-based dosing schedule. As such, it will provide the most robust evidence to date on dextromethorphan utilization for postoperative pain control following TKA. Limitations include not obtaining serum samples for pharmacokinetic analysis and the single-center study design. Trial registration This trial has been registered on the National Institute of Health's Clini calTr ials. gov (NCT number: NCT05278494). Registered on March 14, 2022.

Gene Therapy, Oct 11, 2022

Human adipose-derived mesenchymal stem cells (ASCs) transduced with a lentiviral vector system to... more Human adipose-derived mesenchymal stem cells (ASCs) transduced with a lentiviral vector system to express bone morphogenetic protein 2 (LV-BMP-2) have been shown to reliably heal bone defects in animal models. However, the influence of donor characteristics such as age, sex, race, and medical co-morbidities on ASC yield, growth and bone regenerative capacity, while critical to the successful clinical translation of stem cell-based therapies, are not well understood. Human ASCs isolated from the infrapatellar fat pads in 122 ASC donors were evaluated for cell growth characteristics; 44 underwent additional analyses to evaluate in vitro osteogenic potential, with and without LV-BMP-2 transduction. We found that while female donors demonstrated significantly higher cell yield and ASC growth rates, age, race, and the presence of co-morbid conditions were not associated with differences in proliferation. Donor demographics or the presence of comorbidities were not associated with differences in in vitro osteogenic potential or stem cell differentiation, except that transduced ASCs from healthy donors produced more BMP-2 at day 2. Overall, donor age, sex, race, and the presence of co-morbid conditions had a limited influence on cell yield, proliferation, self-renewal capacity, and osteogenic potential for non-transduced and transduced (LV-BMP-2) ASCs. These results suggest that ASCs are a promising resource for both autologous and allogeneic cell-based gene therapy applications.

Journal of Biomedical Materials Research Part A, May 21, 2021

At the present time there are no consistently satisfactory treatment options for some challenging... more At the present time there are no consistently satisfactory treatment options for some challenging bone loss scenarios. We have previously reported on the properties of a novel 3D‐printed hydroxyapatite‐composite material in a pilot study, which demonstrated osteoconductive properties but was not tested in a rigorous, clinically relevant model. We therefore utilized a rat critical‐sized femoral defect model with a scaffold designed to match the dimensions of the bone defect. The scaffolds were implanted in the bone defect after being loaded with cultured rat bone marrow cells (rBMC) transduced with a lentiviral vector carrying the cDNA for BMP‐2. This experimental group was compared against 3 negative and positive control groups. The experimental group and positive control group loaded with rhBMP‐2 demonstrated statistically equivalent radiographic and histologic healing of the defect site (p > 0.9), and significantly superior to all three negative control groups (p < 0.01). However, the healed defects remained biomechanically inferior to the unoperated, contralateral femurs (p < 0.01). When combined with osteoinductive signals, the scaffolds facilitate new bone formation in the defect. However, the scaffold alone was not sufficient to promote adequate healing, suggesting that it is not substantially osteoinductive as currently structured. The combination of gene therapy with 3D‐printed scaffolds is quite promising, but additional work is required to optimize scaffold geometry, cell dosage and delivery.

Journal of Biomechanics, 2011

Long-term clinical follow-up studies have shown that radiolucent lines at the cement interfaces o... more Long-term clinical follow-up studies have shown that radiolucent lines at the cement interfaces of total hip replacement femoral components develop gradually, ultimately leading to loosening. In this experimental study, 32 synthetic femurs implanted with cemented femoral components were cyclically loaded with a dynamic joint reaction force, torque, and muscle force, to assess the relative effects of surface finish and collars on interface fixation. Four each of four otherwise identical straight femoral stems, varying only in surface finish and presence or lack of collars were used. Specimens were tested under two conditions: (1) with intact interfaces simulating immediate post-operative conditions and (2) with a thin-film at the stem-cement interface, simulating conditions several weeks to months post-operative when fibrous tissue has formed with the implant still stable. Micromotion was measured at both interfaces in three directions. Surface finish had a larger relative effect than collars, regardless of whether or not a thin-film was present. For example, a proximal grit-blasted finish enhanced fixation at the stem-cement interface by 7-12 μm per-cycle (p<0.05) and decreased early cement mantle loosening by 7-13 μm. For straight stems, rougher surfaces provided greater stability than polished, even with a thin film at the stem-cement interfaces, contradicting the theory that once debonded, rough stems are less stable than polished at the stem-cement interface. The findings of this experimental study exemplify the need to take advantage of all available tools for the preclinical evaluation of orthopaedic implants, including long-term clinical observations of related devices, analytical and numeric models, and experimental bench-top simulations.

Journal of Bone and Joint Surgery, American Volume, 2004

The optimum surface roughness of cemented femoral stems used for total hip replacement is a subje... more The optimum surface roughness of cemented femoral stems used for total hip replacement is a subject of controversy. While rougher surfaces provide stronger cement adhesion, it has been hypothesized that polished, tapered, noncollared stems settle into the cement mantle, providing improved stability. However, the effects of surface finish on the stability of straight, cemented stems tapered only in the coronal plane are not known. Using composite model femora, we assessed the initial stability of a straight, cemented femoral stem as a function of surface roughness, the presence or absence of a collar, stem size, and the resultant cement thickness under simulated walking and stair-climbing loads. Otherwise identical stems were manufactured with polished or rough surfaces, with or without a collar, in two different sizes. We isolated these three variables and compared their relative contributions to the motion at the stem-cement interface throughout cyclic loading. We defined three indicators of stability: per-cycle motion, rate of migration, and final migration. Surface roughness had a greater influence on per-cycle motions than did the presence or absence of a collar or cement thickness. Specifically, in the medial-lateral direction, per-cycle motion of polished stems was 43 micro m greater than that of rough stems (p < 0.01). None of the per-cycle motions decreased over the 77,000 load cycles. In contrast, with all stems, the rate of migration decreased over the course of cyclic loading, but the rate of migration of the polished stems was greater than that of the rough stems. Final migrations of the stems over the course of loading were generally distal, medial, and into retroversion. Compared with rough stems, polished stems had 8 to 18 micro m more axial migration (p < 0.001), 48 micro m more anterior-posterior migration (p < 0.001), and 0.4 degrees more rotational migration (p = 0.01). and The results indicated that, for cemented, straight femoral stems tapered only in the coronal plane, a rough surface offers the advantage of less per-cycle motion. These results may apply to widely used cemented stem designs based on the profile of the original Charnley femoral component, which has approximately parallel anterior and posterior aspects.

Clinical Orthopaedics and Related Research, Jul 1, 1995

Journal of Arthroplasty, 1998

Release of static and dynamic contractures around the hip provides significant immediate benefits... more Release of static and dynamic contractures around the hip provides significant immediate benefits for the patient and accelerates postoperative rehabilitation. Knee pain is decreased, groin pain is eliminated, range of motion of the hip is increased, and functional leg-length difference is reduced. This article emphasizes the imponance of techniques used to ensure soft tissue balance.

Journal of the American Academy of Orthopaedic Surgeons, Mar 1, 2022

Introduction: Rapid recovery protocols (RRPs) for total joint arthroplasty (TJA) can reduce hospi... more Introduction: Rapid recovery protocols (RRPs) for total joint arthroplasty (TJA) can reduce hospital length of stay (LOS) and improve patient care in select cohorts; however, there is limited literature regarding their utility in marginalized patient populations. This report aimed to evaluate the outcomes of an institutional RRP for TJA at a safety net hospital. Methods: A retrospective review of 573 primary TJA patients was done, comparing the standard recovery protocol (n = 294) and RRP cohorts (n = 279). Measured outcomes included LOS, 90-day complications, revision surgeries, readmissions, and emergency department visits. Results: The mean LOS reduced from 3.0 ± 3.1 days in the standard recovery protocol cohort to 1.6 ± 0.9 days in the RRP cohort (P < 0.001). The RRP cohort had significantly fewer 90-day complications (11.1% versus 21.4%, P = 0.005), readmissions (1.4% versus 5.8%, P = 0.007), and revision surgeries (1.4% versus 4.4%, P = 0.047). Conclusion: A RRP for primary TJA can be successfully implemented at a safety net hospital with a shorter LOS and fewer acute adverse events. Such protocols require a coordinated, multidisciplinary effort with strict adherence to evidence-based practices to provide high-quality, value-based surgical health care to an underserved cohort.

DOAJ (DOAJ: Directory of Open Access Journals), Oct 1, 2021

P = 0.017. Overweight (BMI > 25 Kg/m2) and obese patients (BMI30 Kg/m2) had a higher rate of panc... more P = 0.017. Overweight (BMI > 25 Kg/m2) and obese patients (BMI30 Kg/m2) had a higher rate of pancreatic fistula, 9.8% vs. 18.9%, P = 0.044 and 13.1 vs. 22.4%, P = 0.07, respectively; as well as postoperative complications, 42.2% vs. 55%, P = 0.040 and 47.5% vs. 59.7%, P = 0.084. In the multivariable analyses, higher BMI was associated with a higher risk of pancreatic fistula (OR: 2.31, 95% CI: 1.30e4.09) and postoperative complications (OR: 1.08, 1.03e1.14). The costs for hospitalizations and emergency room visits were higher for overweight

Arthroplasty today, Apr 1, 2021

Camurati-Engelmann disease (CED) is an extremely rare, sclerosing bone disorder of intramedullary... more Camurati-Engelmann disease (CED) is an extremely rare, sclerosing bone disorder of intramedullary ossification with only 300 reported cases worldwide. The pathogenesis is related to activating mutations in transforming growth factor beta 1, which results in bilateral, symmetric hyperostosis affecting primarily the diaphysis of long bones. Despite effective pharmacological treatment options, the diagnosis of CED is problematic owning to its rarity and variability of clinical presentation. We present a patient with known CED with advanced early hip osteoarthritis, secondary to underlying hip dysplasia, for which she underwent a successful total hip arthroplasty via a direct anterior approach with the use of bulk femoral head autograft to reconstruct her native acetabulum.

Arthroplasty today, Oct 1, 2021

Background Total joint arthroplasty (TJA) practices have been dramatically impacted by the COVID-... more Background Total joint arthroplasty (TJA) practices have been dramatically impacted by the COVID-19 pandemic. To date, no study has assessed trends in patient perceptions regarding the safety of elective TJA. Methods A single-institution, prospective cohort study was conducted between May 11th and August 10th, 2020. All patients who underwent elective hip and knee arthroplasty were contacted via telephone or emailed surveys. Two-hundred and thirty-five consecutive patients were screened, and 158 agreed to participate. The average age was 65.9 ± 11.5 years, with 51.0% of patients being female. The percentage of participants who underwent total knee, total hip, and unicompartmental knee arthroplasty was 41.4%, 37.6%, and 21.0%, respectively. Survey components assessed demographic data, level of concern and specific concerns about the pandemic, and factors increasing patient comfort in proceeding with surgery. Results Older age (P = .029) and female sex (P = .004) independently predicted higher concern on multivariate analysis. Race (P = .343), surgical site (knee vs hip, P = .58), and procedure type (primary vs revision, P = .26) were not significantly related to degree of concern. Most participants (71.5%) disagreed that the pandemic would negatively affect the outcome of their surgery. Patient concern mirrored statewide COVID-19 cases and deaths, rather than local municipal trends. The most cited reassuring factors were preoperative COVID-19 testing, personal protective equipment usage by hospital staff, and surgeon support. Conclusions Patient concern regarding the safety of elective TJA may follow broader policy-level events rather than local trends. Surgeons should note that universal preoperative COVID-19 testing, adequate personal protective equipment, and surgeon support were reassuring to patients. Level of Evidence Level IV Therapeutic.

Journal of Arthroplasty, May 1, 2023

Journal of Arthroplasty, Jun 1, 2023

Journal of Arthroplasty, Aug 1, 2022

BACKGROUND Advances in surgical technique and prosthesis design have expanded the non-neoplastic ... more BACKGROUND Advances in surgical technique and prosthesis design have expanded the non-neoplastic indications for proximal femoral replacement (PFR) to include fracture nonunion, periprosthetic fracture, and severe bone loss in the setting of revision total hip arthroplasty (THA). The purpose of this study is to assess outcomes of PFRs used for non-oncologic indications. METHODS A single-institution, retrospective cohort survey study was conducted between August 2015-February 2020 of consecutive patients undergoing PFR for non-oncologic indications in revision THA. Patient demographics, surgical variables, complications, and revision procedures were collected. Patient satisfaction and Oxford Hip scores were assessed via telephone questionnaire. Implant survivorship was estimated using the Kaplan-Meier method. RESULTS In total, 24 patients (27 PFRs) were available for analysis with an average age of 69.3±12.9 years (range: 37-90). The average number of operations prior to PFR implantation was 3.1±2.1 (range: 0-7). At mean follow-up of 2.4 years (range: 0.5-5.1), the mean Oxford Hip Score was 31.7±10.2 and mean patient satisfaction was 4.9/5. Six patients (20.7%) experienced a postoperative complication, with dislocation occurring in three patients (10.3%). None of the patients with dual mobility articulations (n=4) dislocated. Three-year survivorship was 85.2% (95%CI 71.8%-98.6%) with all-cause reoperations as the endpoint and 100% (95%CI 100.0%-100.0%) with revision for aseptic loosening as the endpoint. CONCLUSIONS The current study demonstrates excellent short-term survivorship, satisfactory patient-reported outcomes, and high patient satisfaction following PFR for non-oncologic indications during revision THA utilizing modern techniques. The most common mode of failure was dislocation requiring reoperation with revision to constrained acetabular components.

Current Orthopaedics, Oct 1, 1998

ABSTRACT Distal fixation with extensively porous-coated stems has demonstrated good fixation, but... more ABSTRACT Distal fixation with extensively porous-coated stems has demonstrated good fixation, but a high incidence of proximal stress-shielding. Proximal femoral fixation was developed to load the femur proximally to avoid the problem of stress-shielding. First generation proximal fixation stems had a high percentage of thigh pain and loosening. Second generation designs with mechanical fixation only in the diaphysis (smooth distal stems) improved fixation, but still demonstrated a relatively high incidence of thigh pain. It is now evident that biologic fixation is required in the diaphysis. Still, proximal fixation must occur in the cortical bone of the proximal femur. Stems with a geometry that primarily load the proximal femur, and yet achieve biologic (osseous) fixation in the diaphysis, result in ‘transitional stress transfer’ to the femur. Contemporary designs that employ these principles are successful in providing durable fixation, a low incidence of thigh pain, and avoid the problem of stress-shielding.

PubMed, May 1, 2008

Total joint replacement patients today are younger, heavier, and more active than total joint rep... more Total joint replacement patients today are younger, heavier, and more active than total joint replacement patients 40 yrs ago. Consequently, patient expectations and prosthesis requirements have increased and there is a need to re-evaluate preclinical testing methods. We present the design rationale for a novel load simulator for the proximal femur, capable of applying a more aggressive load profile than previous simulators. This simulator was used to measure three-dimensional micromotion of a cemented total hip replacement femoral stem under simulated physiological loading. We assessed the influence of a separate abductor muscle force, a higher joint reaction force, and a more accurate implant stability measurement system included in the new simulator and compared the results to the lower, single joint reaction force included in a previously published simulator. Per-cycle motion at both cement interfaces and stem and cement mantle migration obtained from both simulators using the same femoral stem design, are compared. Although the new simulator applied higher loads, per-cycle motions were lower than previously reported. In both studies, regardless of the presence or lack of a separate muscle force, the greatest motions were in the medial-lateral direction (new: 27 +/- 4 mum, old: 67 +/- 21 mum). The findings indicate that magnitude and direction of peak joint reaction force and inclusion of a separate muscle force have a significant effect on femoral stem stability measurements. We recommend that future femoral stem stability studies consider using load simulation techniques and a direct motion measurement system comparable to the one presented in this study.

Journal of Biomechanics, 2011

In this study, the in vitro fixation of four otherwise identical double-tapered stem-types, varyi... more In this study, the in vitro fixation of four otherwise identical double-tapered stem-types, varying only in surface finish (polished or matte) and proximal stem geometry (with or without flanges) were compared under two conditions. First, four specimens of each stem type were tested with initially bonded stem-cement interfaces, representing early post-operative conditions. Then, simulating conditions a few weeks to months later, stems were implanted in unused synthetic femurs, with a thin layer coating the stem to prevent stem-cement adhesion. Per-cycle motions were measured at both cement interfaces throughout loading. Overall, surface finish had the smallest relative effect on fixation compared to flanges. Flanges increased axial fixation by 22 μm per-cycle, regardless of surface finish (P=0.01). Further, all stems moved under dynamic load at the stem-cement interface during the first few cycles of loading, even without a thin film. The results indicate that flanges have a greater effect on fixation than surface finish, and therefore adverse findings about matte surfaces should not necessarily apply to all double-tapered stems. Specifically, dorsal flanges enhance the stability of a tapered cemented femoral stem, regardless of surface finish.

Journal of Bone and Joint Surgery, American Volume, Apr 1, 2004

Although current designs of cemented femoral stems for total hip replacement include both those w... more Although current designs of cemented femoral stems for total hip replacement include both those with and those without a flanged shape at the proximal end, the influence of anteroposterior dorsal flanges on the fixation of the stem is not completely understood. The purpose of this study was to assess the effects of flanges on femoral stem stability and load transfer to the femur with use of an in vitro model. We measured femoral surface strains and three-dimensional micromotion in synthetic femora under cyclic loading with four types of stems: those with flanges and those without flanges in two sizes each. The four types of stems were otherwise identical; that is, all of them were straight, polished, and collarless. Stem-cement micromotion measurements and strain measurements were repeated with three stems of each type, whereas bone-cement micromotion measurements were made with one stem of each type. Flanges had a greater influence on femoral strains and micromotion than did the difference in the cement thickness resulting from the different stem sizes. Specifically, the flanged stems produced greater strains on the medial femoral surface but smaller strains on the anterior surface than did the non-flanged stems. Flanged stems achieved tighter mechanical interlock within the cement, but these stems increased bone-cement micromotion. Specifically, the motion per cycle of flanged stems within the cement mantle was smaller than that of non-flanged stems, whereas the motion per cycle of the cement mantle within the femoral canal was greater with the flanged stems than with the non-flanged stems. Flanges on a total hip femoral stem increase the interlock between the stem and the cement and decrease the proximal-medial stress-shielding. However, these advantages occur with increased bone-cement interface motion, which may be detrimental to the survival of the implant.

Hip International, Mar 8, 2016

ORIGInAL RESEARCH ARTICLE more stress shielding, and that larger, noncemented, cobaltchromium (Co... more ORIGInAL RESEARCH ARTICLE more stress shielding, and that larger, noncemented, cobaltchromium (CoCr) stems can lead to thigh pain. Conversely, titanium (Ti) alloy stems transfer more load to the surrounding bone (7-9). Despite the vast amount of literature on the subject, it is difficult to quantitatively assess the relative influences of these differences as a function of stem design characteristics. In order to reduce bone loss, investigators have identified key design features that successfully reduce stress shielding. Specifically, previous studies have found that factors such as stem material, fixation method, and surface features appear to greatly influence changes in periprosthetic bone mineral density (BMD) (10-12). Previous studies have shown that the location of femoral stem fixation onto the bone plays a role in bone remodelling, where shorter stems allow the maintenance of more physiologic load transfers to the proximal femur, thereby decreasing overall bone loss following metaphyseal fixation (13). Additionally, some studies have proposed the use of shorter stems for their less invasive surgical techniques that preserve more native bone stock (14, 15). While previous studies have demonstrated that stem design influences bone remodelling, these studies were limited by the comparisons made between specific implants. Some only observed the bone remodelling patterns of 1 specific stem design against a control rather than comparing 2 unique

Trials, Mar 29, 2023

Background Pain management is a critical component of comprehensive postsurgical care, as it infl... more Background Pain management is a critical component of comprehensive postsurgical care, as it influences patient safety and outcomes, and inadequate control has been associated with the development of chronic pain syndromes. Despite recent improvements, the management of postoperative pain following total knee arthroplasty (TKA) remains a challenge. The use of opioid-sparing, multimodal analgesic regimens has broad support, but there is a paucity of high-quality evidence regarding optimal postoperative protocols and novel approaches are needed. Dextromethorphan stands out among both well-studied and emerging pharmacological adjuncts for postoperative pain due its robust safety profile and unique pharmacology. The purpose of this study is to evaluate the efficacy of multi-dose dextromethorphan for postoperative pain control following TKA. Methods This is a single-center, multi-dose, randomized, double-blinded, placebo-controlled trial. A total of 160 participants will be randomized 1:1 to receive either 60 mg oral dextromethorphan hydrobromide preoperatively, as well as 30 mg 8 h and 16 h postoperatively, or matching placebo. Outcome data will be obtained at baseline, during the first 48 h, and the first two follow-up visits. The primary outcome measure will be total opioid consumption at 24 h postoperatively. Secondary outcomes related to pain, function, and quality of life will be evaluated using standard pain scales, the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) questionnaire, the Patient-Reported Outcomes Measurement Information System (PROMIS-29) questionnaire, and clinical anchors. Discussion This study has a number of strengths including adequate power, a randomized controlled design, and an evidence-based dosing schedule. As such, it will provide the most robust evidence to date on dextromethorphan utilization for postoperative pain control following TKA. Limitations include not obtaining serum samples for pharmacokinetic analysis and the single-center study design. Trial registration This trial has been registered on the National Institute of Health's Clini calTr ials. gov (NCT number: NCT05278494). Registered on March 14, 2022.

Gene Therapy, Oct 11, 2022

Human adipose-derived mesenchymal stem cells (ASCs) transduced with a lentiviral vector system to... more Human adipose-derived mesenchymal stem cells (ASCs) transduced with a lentiviral vector system to express bone morphogenetic protein 2 (LV-BMP-2) have been shown to reliably heal bone defects in animal models. However, the influence of donor characteristics such as age, sex, race, and medical co-morbidities on ASC yield, growth and bone regenerative capacity, while critical to the successful clinical translation of stem cell-based therapies, are not well understood. Human ASCs isolated from the infrapatellar fat pads in 122 ASC donors were evaluated for cell growth characteristics; 44 underwent additional analyses to evaluate in vitro osteogenic potential, with and without LV-BMP-2 transduction. We found that while female donors demonstrated significantly higher cell yield and ASC growth rates, age, race, and the presence of co-morbid conditions were not associated with differences in proliferation. Donor demographics or the presence of comorbidities were not associated with differences in in vitro osteogenic potential or stem cell differentiation, except that transduced ASCs from healthy donors produced more BMP-2 at day 2. Overall, donor age, sex, race, and the presence of co-morbid conditions had a limited influence on cell yield, proliferation, self-renewal capacity, and osteogenic potential for non-transduced and transduced (LV-BMP-2) ASCs. These results suggest that ASCs are a promising resource for both autologous and allogeneic cell-based gene therapy applications.

Journal of Biomedical Materials Research Part A, May 21, 2021

At the present time there are no consistently satisfactory treatment options for some challenging... more At the present time there are no consistently satisfactory treatment options for some challenging bone loss scenarios. We have previously reported on the properties of a novel 3D‐printed hydroxyapatite‐composite material in a pilot study, which demonstrated osteoconductive properties but was not tested in a rigorous, clinically relevant model. We therefore utilized a rat critical‐sized femoral defect model with a scaffold designed to match the dimensions of the bone defect. The scaffolds were implanted in the bone defect after being loaded with cultured rat bone marrow cells (rBMC) transduced with a lentiviral vector carrying the cDNA for BMP‐2. This experimental group was compared against 3 negative and positive control groups. The experimental group and positive control group loaded with rhBMP‐2 demonstrated statistically equivalent radiographic and histologic healing of the defect site (p &gt; 0.9), and significantly superior to all three negative control groups (p &lt; 0.01). However, the healed defects remained biomechanically inferior to the unoperated, contralateral femurs (p &lt; 0.01). When combined with osteoinductive signals, the scaffolds facilitate new bone formation in the defect. However, the scaffold alone was not sufficient to promote adequate healing, suggesting that it is not substantially osteoinductive as currently structured. The combination of gene therapy with 3D‐printed scaffolds is quite promising, but additional work is required to optimize scaffold geometry, cell dosage and delivery.

Journal of Biomechanics, 2011

Long-term clinical follow-up studies have shown that radiolucent lines at the cement interfaces o... more Long-term clinical follow-up studies have shown that radiolucent lines at the cement interfaces of total hip replacement femoral components develop gradually, ultimately leading to loosening. In this experimental study, 32 synthetic femurs implanted with cemented femoral components were cyclically loaded with a dynamic joint reaction force, torque, and muscle force, to assess the relative effects of surface finish and collars on interface fixation. Four each of four otherwise identical straight femoral stems, varying only in surface finish and presence or lack of collars were used. Specimens were tested under two conditions: (1) with intact interfaces simulating immediate post-operative conditions and (2) with a thin-film at the stem-cement interface, simulating conditions several weeks to months post-operative when fibrous tissue has formed with the implant still stable. Micromotion was measured at both interfaces in three directions. Surface finish had a larger relative effect than collars, regardless of whether or not a thin-film was present. For example, a proximal grit-blasted finish enhanced fixation at the stem-cement interface by 7-12 μm per-cycle (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;amp;amp;amp;amp;lt;0.05) and decreased early cement mantle loosening by 7-13 μm. For straight stems, rougher surfaces provided greater stability than polished, even with a thin film at the stem-cement interfaces, contradicting the theory that once debonded, rough stems are less stable than polished at the stem-cement interface. The findings of this experimental study exemplify the need to take advantage of all available tools for the preclinical evaluation of orthopaedic implants, including long-term clinical observations of related devices, analytical and numeric models, and experimental bench-top simulations.

Journal of Bone and Joint Surgery, American Volume, 2004

The optimum surface roughness of cemented femoral stems used for total hip replacement is a subje... more The optimum surface roughness of cemented femoral stems used for total hip replacement is a subject of controversy. While rougher surfaces provide stronger cement adhesion, it has been hypothesized that polished, tapered, noncollared stems settle into the cement mantle, providing improved stability. However, the effects of surface finish on the stability of straight, cemented stems tapered only in the coronal plane are not known. Using composite model femora, we assessed the initial stability of a straight, cemented femoral stem as a function of surface roughness, the presence or absence of a collar, stem size, and the resultant cement thickness under simulated walking and stair-climbing loads. Otherwise identical stems were manufactured with polished or rough surfaces, with or without a collar, in two different sizes. We isolated these three variables and compared their relative contributions to the motion at the stem-cement interface throughout cyclic loading. We defined three indicators of stability: per-cycle motion, rate of migration, and final migration. Surface roughness had a greater influence on per-cycle motions than did the presence or absence of a collar or cement thickness. Specifically, in the medial-lateral direction, per-cycle motion of polished stems was 43 micro m greater than that of rough stems (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;amp;amp;amp;amp;lt; 0.01). None of the per-cycle motions decreased over the 77,000 load cycles. In contrast, with all stems, the rate of migration decreased over the course of cyclic loading, but the rate of migration of the polished stems was greater than that of the rough stems. Final migrations of the stems over the course of loading were generally distal, medial, and into retroversion. Compared with rough stems, polished stems had 8 to 18 micro m more axial migration (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;amp;amp;amp;amp;lt; 0.001), 48 micro m more anterior-posterior migration (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;amp;amp;amp;amp;lt; 0.001), and 0.4 degrees more rotational migration (p = 0.01). and The results indicated that, for cemented, straight femoral stems tapered only in the coronal plane, a rough surface offers the advantage of less per-cycle motion. These results may apply to widely used cemented stem designs based on the profile of the original Charnley femoral component, which has approximately parallel anterior and posterior aspects.

Clinical Orthopaedics and Related Research, Jul 1, 1995

Journal of Arthroplasty, 1998

Release of static and dynamic contractures around the hip provides significant immediate benefits... more Release of static and dynamic contractures around the hip provides significant immediate benefits for the patient and accelerates postoperative rehabilitation. Knee pain is decreased, groin pain is eliminated, range of motion of the hip is increased, and functional leg-length difference is reduced. This article emphasizes the imponance of techniques used to ensure soft tissue balance.

Journal of the American Academy of Orthopaedic Surgeons, Mar 1, 2022

Introduction: Rapid recovery protocols (RRPs) for total joint arthroplasty (TJA) can reduce hospi... more Introduction: Rapid recovery protocols (RRPs) for total joint arthroplasty (TJA) can reduce hospital length of stay (LOS) and improve patient care in select cohorts; however, there is limited literature regarding their utility in marginalized patient populations. This report aimed to evaluate the outcomes of an institutional RRP for TJA at a safety net hospital. Methods: A retrospective review of 573 primary TJA patients was done, comparing the standard recovery protocol (n = 294) and RRP cohorts (n = 279). Measured outcomes included LOS, 90-day complications, revision surgeries, readmissions, and emergency department visits. Results: The mean LOS reduced from 3.0 ± 3.1 days in the standard recovery protocol cohort to 1.6 ± 0.9 days in the RRP cohort (P < 0.001). The RRP cohort had significantly fewer 90-day complications (11.1% versus 21.4%, P = 0.005), readmissions (1.4% versus 5.8%, P = 0.007), and revision surgeries (1.4% versus 4.4%, P = 0.047). Conclusion: A RRP for primary TJA can be successfully implemented at a safety net hospital with a shorter LOS and fewer acute adverse events. Such protocols require a coordinated, multidisciplinary effort with strict adherence to evidence-based practices to provide high-quality, value-based surgical health care to an underserved cohort.

DOAJ (DOAJ: Directory of Open Access Journals), Oct 1, 2021

P = 0.017. Overweight (BMI > 25 Kg/m2) and obese patients (BMI30 Kg/m2) had a higher rate of panc... more P = 0.017. Overweight (BMI > 25 Kg/m2) and obese patients (BMI30 Kg/m2) had a higher rate of pancreatic fistula, 9.8% vs. 18.9%, P = 0.044 and 13.1 vs. 22.4%, P = 0.07, respectively; as well as postoperative complications, 42.2% vs. 55%, P = 0.040 and 47.5% vs. 59.7%, P = 0.084. In the multivariable analyses, higher BMI was associated with a higher risk of pancreatic fistula (OR: 2.31, 95% CI: 1.30e4.09) and postoperative complications (OR: 1.08, 1.03e1.14). The costs for hospitalizations and emergency room visits were higher for overweight

Arthroplasty today, Apr 1, 2021

Camurati-Engelmann disease (CED) is an extremely rare, sclerosing bone disorder of intramedullary... more Camurati-Engelmann disease (CED) is an extremely rare, sclerosing bone disorder of intramedullary ossification with only 300 reported cases worldwide. The pathogenesis is related to activating mutations in transforming growth factor beta 1, which results in bilateral, symmetric hyperostosis affecting primarily the diaphysis of long bones. Despite effective pharmacological treatment options, the diagnosis of CED is problematic owning to its rarity and variability of clinical presentation. We present a patient with known CED with advanced early hip osteoarthritis, secondary to underlying hip dysplasia, for which she underwent a successful total hip arthroplasty via a direct anterior approach with the use of bulk femoral head autograft to reconstruct her native acetabulum.

Arthroplasty today, Oct 1, 2021

Background Total joint arthroplasty (TJA) practices have been dramatically impacted by the COVID-... more Background Total joint arthroplasty (TJA) practices have been dramatically impacted by the COVID-19 pandemic. To date, no study has assessed trends in patient perceptions regarding the safety of elective TJA. Methods A single-institution, prospective cohort study was conducted between May 11th and August 10th, 2020. All patients who underwent elective hip and knee arthroplasty were contacted via telephone or emailed surveys. Two-hundred and thirty-five consecutive patients were screened, and 158 agreed to participate. The average age was 65.9 ± 11.5 years, with 51.0% of patients being female. The percentage of participants who underwent total knee, total hip, and unicompartmental knee arthroplasty was 41.4%, 37.6%, and 21.0%, respectively. Survey components assessed demographic data, level of concern and specific concerns about the pandemic, and factors increasing patient comfort in proceeding with surgery. Results Older age (P = .029) and female sex (P = .004) independently predicted higher concern on multivariate analysis. Race (P = .343), surgical site (knee vs hip, P = .58), and procedure type (primary vs revision, P = .26) were not significantly related to degree of concern. Most participants (71.5%) disagreed that the pandemic would negatively affect the outcome of their surgery. Patient concern mirrored statewide COVID-19 cases and deaths, rather than local municipal trends. The most cited reassuring factors were preoperative COVID-19 testing, personal protective equipment usage by hospital staff, and surgeon support. Conclusions Patient concern regarding the safety of elective TJA may follow broader policy-level events rather than local trends. Surgeons should note that universal preoperative COVID-19 testing, adequate personal protective equipment, and surgeon support were reassuring to patients. Level of Evidence Level IV Therapeutic.