Limited Durability of Extensor Mechanism Reconstruction Following Total Knee Arthroplasty: Mesh and Allograft Show Equivalent Outcomes at Five-Year Follow-Up.

BACKGROUND: Extensor mechanism disruption is a challenging complication following total knee arthroplasty. The purpose of this study was to compare outcomes between patients who received mesh versus allograft extensor mechanism reconstruction. METHODS: All patients who underwent extensor mechanism reconstruction at a single institution were screened. Demographic and surgical variables were recorded, including technique (ie, synthetic mesh versus allograft reconstruction). Patients were assessed for preoperative and postoperative extensor lag, revision, and duration of follow-up. Analyses, including Kaplan-Meier survivorships, were performed to compare mesh to allograft reconstruction. In total, 50 extensor mechanism reconstructions (30 mesh and 20 allograft) were conducted between January 1st, 2001, and December 31st, 2022. RESULTS: There were no differences between the cohorts with respect to revision (26.7 [8 of 30] versus 35.0% [7 of 20], P = .680) or failure defined as above knee amputation or fusion (6.7 [2 of 30] versus 5.0% [1 of 20], P = .808). There were also no differences in time to reoperation (average 27 months [range, 6.7 to 58.8] versus 29 months [range, 1.2 to 84.9], P = .910) or in postoperative extensor lag among patients who did not undergo a reoperation (13 [0 to 50] versus 11° [0 to 30], P = .921). The estimated 5-year Kaplan-Meier survival with extensor mechanism revision as the endpoint was similar between the 2 groups (52.1, 95% confidence interval [CI] = 25.4 to 73.3 versus 55.0%, 95% CI = 23.0 to 78.4%, P = .990). CONCLUSIONS: The purpose of this study was to present the findings of a large cohort of patients who required extensor mechanism reconstruction. Regardless of the reconstruction type, the 5-year outcomes of patients requiring extensor mechanism reconstruction are suboptimal.

Factors Associated With Failure Following Proximal Femoral Replacement for Salvage Hip Surgery for Nononcologic Indications.

BACKGROUND: Proximal femoral replacement (PFR) is used when extensive proximal femoral bone loss is encountered during revision total hip arthroplasty. However, further data on 5-to-10-year survivorship and predictors of failure are needed. Our aim was to assess the survivorship of contemporary PFRs used for nononcologic indications and determine factors associated with failure. METHODS: A single-institution retrospective observational study was conducted between June 1, 2010 and August 31, 2021 for patients undergoing PFR for non-neoplastic indications. Patients were followed for a minimum of 6 months. Demographic, operative, clinical, and radiographic data were collected. Implant survivorship was determined via Kaplan-Meier analysis of 56 consecutive cemented PFRs in 50 patients. RESULTS: At a mean follow-up of 4 years, the mean Oxford Hip Score was 36.2 and patient satisfaction was rated at an average of 4.7 of 5 on the Likert scale. Radiographic evidence of femoral-sided aseptic loosening was determined in 2 PFRs at a median of 9.6 years. The 5-year survivorship with all-cause reoperation and revision as end points was 83.2% (95% Confidence Interval [CI]: 70.1% to 91.0%) and 84.9% (95% CI: 72.0% to 92.2%), respectively. The 5-year survivorship was 92.3% (95% CI: 78.0% to 97.5%) for stem length > 90 mm compared to 68.4% (95% CI: 39.5% to 85.7%) for stem length ≤ 90 mm. A construct-to-stem length ratio (CSR) ≤ 1 was associated with a 91.7% (95% CI: 76.4% to 97.2%) survival, while a CSR > 1 was associated with a 73.6% (95% CI: 47.4% to 88.1%) survival. CONCLUSION: A PFR stem length ≤ 90 mm and CSR > 1 were associated with increased rates of failure.

Influence of donor age and comorbidities on transduced human adipose-derived stem cell in vitro osteogenic potential.

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.

Modern Proximal Femoral Replacement in Revision Total Hip Arthroplasty for Nononcologic Indications.

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 nononcologic indications. METHODS: A single-institution, retrospective, cohort survey study was conducted between August 2015-February 2020 of consecutive patients undergoing PFR for nononcologic indications in revision THA. Patient demographics, surgical variables, complications, and revision procedures were collected. Patient satisfaction and Oxford Hip scores were assessed via a 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 a 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) had dislocation. 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. CONCLUSION: The current study demonstrates excellent short-term survivorship, satisfactory patient-reported outcomes, and high patient satisfaction following PFR for nononcologic indications during revision THA utilizing modern techniques. The most common mode of failure was dislocation requiring reoperation with revision to constrained acetabular components.

Patient Perception Regarding the Safety of Elective Joint Arthroplasty Surgery During the COVID-19 Pandemic.

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.

Anterior Total Hip Arthroplasty With Bulk Femoral Head Autograft in a Patient With Camurati-Engelmann Disease.

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.

Periprosthetic femoral bone loss in total hip arthroplasty: systematic analysis of the effect of stem design.

INTRODUCTION: Periprosthetic bone loss may lead to major complications in total hip arthroplasty (THA), including loosening, migration, and even fracture. This study analysed the influence of femoral implant designs on periprosthetic bone mineral density (BMD) after THA. METHODS: The results of all previous published studies reporting periprosthetic femoral BMD following THA were compiled. Using these results, we compared percent changes in bone loss as a function of: femoral stem fixation, material, and geometry. RESULTS: The greatest bone loss was in the calcar region (Gruen Zone 7). Overall, cemented stems had more bone loss distally than noncemented stems, while noncemented stems had more proximal bone loss than cemented stems. Within noncemented stems, cobalt-chromium (CoCr) stems had nearly double the proximal bone loss compared to titanium (Ti) alloy stems. Finally, within noncemented titanium alloy group, straight stems had less bone loss than anatomical, tapered, and press-fit designs. DISCUSSION: The findings from the present study quantified percent changes in periprosthetic BMD as a function of fixation method, alloy, and stem design. While no one stem type was identified as ideal, we now have a clearer understanding of the influence of stem design on load transfer to the surrounding bone.

Effects of dorsal flanges on fixation of a cemented total hip replacement femoral stem.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Initial stability of cemented femoral stems as a function of surface finish, collar, and stem size.

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: and CLINICAL RELEVANCE: 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.

Polyethylene liner cementation into fixed acetabular shells.

A patient presenting with a secure cementless acetabular component and with femoral head penetration through the polyethylene liner is a common clinical problem. Cementing a new liner into the fixed shell is one option. We evaluated this option in a clinical series of 17 cases and with a preliminary mechanical study. In the 1 clinical failure (5.9%), the failure occurred at the cement-liner interface. The most important variable in optimizing the mechanical strength of the cemented liner construct was adequate preparation of the cement-liner interface. This approach to treating the patient with a fixed cementless shell and a worn polyethylene liner can provide a durable construct with minimal morbidity.