Faculty Bibliography

BACKGROUND:As the clinical and financial environments of total joint arthroplasty (TJA) have evolved over the last several decades so has the role of the surgeon in providing this care to patients. Our objective was to examine current practices and influential factors among fellowship-trained arthroplasty surgeons. METHODS:An electronic survey was sent to all surgeons who had completed one of the three high-volume adult reconstruction fellowships from the years 2007-2016. The survey consisted of 34 questions regarding current practice characteristics, case volumes for primary and revision total hip arthroplasty (THA) and total knee arthroplasty (TKA), use of advanced technologies, choice of surgical approach and implant design, factors influencing their choices, and their involvement in implant selection and contract negotiations. RESULTS:Questionnaires were sent to 53 surgeons; 52 were completed. Sixty percent of respondents performed at least 100 TKAs and 84% performed at least 50 THAs annually. Ninety-four percent use a single company's implant for more than 90% of primary TKA and THA. Fellowship or residency experience was the most significant influence on TKA and THA implant selection for 62% and 45% of surgeons, respectively, while contracts of their current institution were the primary influence for 17% and 12%, respectively. Fifty-five percent of surgeons used some advanced technology of which 16% said this influenced their implant choice. Eighty-six percent perform the majority of cases at centers performing at least 200 TJAs per year, and 39% participate in implant contract negotiations. CONCLUSION/CONCLUSIONS:Despite changes in the economic environment of TJA, this study demonstrates that experience with a specific implant during training, particularly fellowship, is the most influential factor for implant selection among fellowship-trained arthroplasty surgeons.

BACKGROUND:Short-stem (SS) hip prostheses for total hip arthroplasty (THA) have gained popularity as surgeons strive to reproduce physiological stress distributions at the proximal femur. Additionally, as THA indications continue to target younger populations, preservation of femoral bone stock for potential revision surgeries is particularly appealing. However, little is known regarding the short-term complications of each variety of short stem during the learning curve period. The purpose of this study is to evaluate the short-term complications among the THA recipients with the use of a novel SS hip prosthesis. METHODS:A retrospective chart review was performed of all patients undergoing primary THA utilizing an Echo Bi-Metric Microplasty hip stem. Patient demographics, surgical factors, complications and quality outcomes were collected utilizing our institution's data warehouse and verified by chart review. RESULTS:In total, 182 SSs were implanted in 168 patients undergoing primary THA. Of these, 5 (2.9%) patients sustained a periprosthetic fracture. Two fractures occurred during the index hospital admission, and 3 occurred in the post-discharge period. Subset analysis demonstrated that 4 (80%) fractures had occurred during the initial learning curve period, within the first 30 surgical cases with a SS. CONCLUSION/CONCLUSIONS:Short-stem hip prostheses are a safe alternative for THA. The results of the present study demonstrate a fracture incidence of 2.9% among patients. However, surgeons should remain cautious when utilizing new implant system and expect a learning curve. In this study, 80% of periprosthetic fractures following SS THA occurred within the first 30 cases for experienced arthroplasty-trained surgeons.

Introduction/UNASSIGNED:Preliminary analysis of accelerometry measurements has shown physical activity may not increase significantly after total knee arthroplasty (TKA). This study evaluates the effect of TKA on physical activity accelerometry measurements and body mass index (BMI). Methods/UNASSIGNED:tests. Results/UNASSIGNED:Twenty-three patients from the OAI database were identified for the paired analysis. They were evaluated at a mean postoperative follow-up of 15 months. There were no statistically significant differences between the post-TKA group and pre-TKA group for the accelerometry variables and BMI, though patients experienced a significant improvement in knee function and pain relief measures included in this analysis. Discussion/UNASSIGNED:Although TKA can successfully restore function and relieve pain, there remains no good evidence that neither physical activity nor BMI improve postoperatively. Conclusion/UNASSIGNED:No significant differences in physical activity and BMI were observed after TKA in this study.

Successful arthroplasty of the knee requires a stable foundation for implant placement, adequate mechanical alignment, and durable fixation. In the revision setting, the later may be difficult to obtain, especially in the setting of significant bone loss. While augments, cones, and sleeves have greatly enhanced the modern knee surgeon's ability to gain fixation in metaphyseal bone, stems continue to be a cornerstone tool in revision arthroplasty to bypass deficient or damaged bone surfaces to enhance structural stability of a revision construct. When placing a revision construct, there remains two options to assist with fixation, either fully cementing the entire implant or using a "hybrid" system, which combines an uncemented press-fit diaphyseal stem with cement in both the metaphysis and metaphysis-diaphysis junction of the keel. In this review, we discuss the history of these two techniques, evaluate the theoretical benefits and pitfalls, and assess the best evidence supporting each in the literature. To conclude, we will examine future directions and questions needed to better elucidate the best treatment options in a variety of revision scenarios.

BACKGROUND:Although preoperative risk assessment tools have been effective in predicting discharge disposition after total joint arthroplasty (TJA), studies reporting on discharge planning in extended length of stay (ELOS), >3 days, patients are lacking. The purpose of this study was to describe the predictive utility of the Risk Assessment and Prediction Tool (RAPT) for discharge disposition in ELOS patients. METHODS:Our study included 260 patients with LOS >3 days who underwent primary TJA between 2014 and 2016. Patients were separated into 3 cohorts, based on their RAPT score: low risk (9-12), medium risk (6-9), and high risk for discharge to a facility (1-6). Scores were compared among cohorts and correlated with discharge disposition for patients who stayed beyond 3 days. RESULTS:In ELOS, RAPT had a higher utility in predicting discharge disposition in the low-risk (76.5% to home) and high-risk (62.9% to facility) patient cohorts, while medium-risk patients (56.5% to home) were the least accurate. Responses that significantly correlated with discharge home included male gender (odds ratio [OR], 1.81; P < .05), ambulation without walking aids (OR, 2.94; P < .01) or a single-point cane (OR, 2.95; P < .0001), <1 community support visit per week preoperatively (OR, 1.86; P < .05), and having support from someone at home (OR, 3.43; P < .0001). CONCLUSION/CONCLUSIONS:The RAPT score in ELOS patients is better correlated with the low-risk and high-risk cohorts than in medium-risk patients. Conversely, medium-risk ELOS patients constituted 56.8% of our sample size, but only predicted 56.5% of discharge dispositions correctly. Future discharge disposition risk assessment tools are needed to stratify medium-risk patients.

BACKGROUND:Advancements in the management of human immunodeficiency virus (HIV) now permit HIV-positive patients to have longer life spans, increasing their cumulative risk of developing an advanced degenerative joint disease, necessitating total hip arthroplasty (THA). The purpose of this study was to provide an extended follow-up on a previously published study on a cohort of HIV-positive THA recipients in an effort to confirm the safety and longevity of THA in this population. METHODS:This study is a follow-up on a previous study comprised of 41 hips in 31 HIV-positive THA recipients. At this follow-up, 5 patients from the original cohort required contralateral THA. Postoperative complications were recorded up to the patient's last follow-up date. A survivorship analysis was performed using the Kaplan-Meier method with revision THA as the end point. RESULTS:Since the last report, 2 additional hips were revised (one for aseptic loosening and one for a periprosthetic fracture), and 5 patients underwent contralateral THA. This resulted in a total of 5 (13.8%) hips requiring revision THA at the latest follow-up. The mean follow-up interval for the original cohort and for the contralateral 5 hips was 78.9 ± 50.2 months and 54.6 ± 45.3 months, respectively. Kaplan-Meier survivorship analysis with revision THA for any reason as the end point demonstrated survivorship of 93% (2 years), 90% (5 years), and 81% (10 and 14 years) after primary THA, respectively. CONCLUSION/CONCLUSIONS:Our study suggests that it is possible to achieve a low incidence of postoperative infection in HIV-positive THA recipients. In addition, our study demonstrates that non-hemophiliac HIV-positive patients have comparable revision rates to previously published reports on HIV-negative patients of similar age, underscoring the clinical efficacy of highly active antiretroviral therapy.

Despite the development of newer preventative measures, the rate of infection continues to be approximately 1% for patients undergoing total joint arthroplasty (TJA). The extent of the infection can range from a mild superficial infection to a more serious periprosthetic joint infection (PJI). PJIs not only play a significant role in the clinical well-being of the TJA patient population, but also have substantial economic implications on the health care system. Several approaches are currently being used to mitigate the risk of PJI after TJA. The variety of prophylactic measures to prevent infection after TJA must be thoroughly discussed and evaluated.

BACKGROUND:Patients with chronic hepatitis C (HCV) have had extremely high complication rates after total hip arthroplasty (THA). We sought to compare perioperative complication rates between untreated and treated HCV in THA patients and to compare these rates between patients treated with 2 different therapies (interferon vs direct antiviral agents). METHODS:A multicenter retrospective database query was used to identify patients diagnosed with HCV who underwent THA between 2006 and 2016. All patients (n = 105) identified were included and divided into 2 groups: untreated (n = 63) and treated (n = 42) HCV; treated patients were further subdivided into those receiving interferon (n = 16) or direct antiviral agent therapies (n = 26). Comparisons between the treated and untreated groups were made with respect to demographic data, comorbidities, preoperative viral load, Model for End-Stage Liver Disease score, and all surgical and medical complications; a subgroup analysis of the treated patients was also performed. Separate independent t-tests or Mann-Whitney U tests were conducted for continuous variables. Categorical variables were compared using the chi-squared test of independence. RESULTS:A greater number of untreated patients were human immunodeficiency virus infected (P = .01), while a reduced number of treated patients were either former or current smokers (P = .004). The untreated group had greater surgical complication rates (25.4% vs 4.8%; P = .007), with a higher rate of periprosthetic joint infection (14.3% vs 0%, P = .01). For treated patients, no differences were observed between treatment types for postsurgical complications. CONCLUSION/CONCLUSIONS:Treatment for HCV prior to THA appears to be associated to fewer postoperative complications, primarily periprosthetic joint infection. Although further investigation is warranted, strong consideration should be given to treating patients for HCV prior to elective THA.

Proper ligament tension in knee flexion within cruciate-retaining (CR) total knee arthroplasty has long been associated with clinical success; however, traditional balancing principles have assumed that the distal femoral joint line (DFJL) affects only extension. The purpose of this study was to determine the effect DFJL may have on ligament strains and tibiofemoral kinematics of CR knee designs in flexion. A computational analysis was performed using a musculoskeletal modeling system for two different knee implants, the high-flex CR (HFCR) and guided-motion CR (GMCR). Tibiofemoral kinematics and ligament strain were measured at 90-degree knee flexion while the implants' DFJL was incrementally shifted proximally. Femoral implant position and kinematics were used to determine the femur's anteroposterior position relative to the tibia. The change in the femoral medial condyle position relative to the tibia was 0.33 mm and 0.53 mm more anterior per each 1-mm elevation of the DFJL for HFCR and GMCR, respectively. The change in the lateral condyle position was 0.20 mm more anterior and 0.06 mm more posterior for HFCR and GMCR, respectively. The strain in the lateral and medial collateral ligaments changed minimally with elevation of the DFJL. In both implants, strain increased in the anterior lateral and posterior medial bundles of the posterior collateral ligament with elevation of the DFJL, whereas strain decreased in the iliotibial band and iliotibial patellar band. Our findings suggest that DFJL affects ligament tension at 90-degree knee flexion and therefore flexion balance for CR implants. Elevating the DFJL to address tight extension space in a CR knee while flexion space is well balanced could result in increased flexion tension especially when the flexion-extension mismatch is large. To achieve balanced flexion and extension, the amount of DFJL elevation may need to be reduced.

Despite the overall successful outcomes following primary total knee arthroplasty (TKA) and the concept that a well-balanced TKA yields a more successful result, concerns still remain in the reported literature regarding the patellofemoral joint. Diminished outcomes have been associated with poorly balanced or placed patella implants. The effect of different techniques to achieve flexion-extension balance and the use of posterior stabilized (PS) versus cruciate retaining (CR) implant designs on patellofemoral balancing has not been previously studied. The purpose of this study is to utilize a validated computational analysis software to simulate the effects of varying implant positions and sizes of femoral components. The patellofemoral retinaculum (PFR) load was significantly affected by some conditions, while others did not reach significance. The proximal-distal implant position with knee flexion angle (p < 0.001), the implant size (p < 0.001), and the implant bearing type (CR/PS) (p < 0.05) were significant. For the proximal-distal implant position and knee flexion angle, a more proximal implant position (elevating the joint line) increased the PFR load from 15 to 30°, and a more proximal implant position reduced retinaculum load from 60 to 135°. However, at 45°, implant position does not affect retinaculum load. Achieving the appropriate balance between the dynamic nature of both the tibiofemoral and the patellofemoral interaction in TKA has proven to be complex and challenging to manage. Balancing of a TKA is essential to the proper functioning and overall longevity of the implant. These results demonstrate that patellofemoral balance is affected by implant size and position during flexion-extension gap balancing.