Faculty Bibliography

BACKGROUND:The advent of highly cross-linked polyethylene (HCLPE) has significantly improved total hip arthroplasty survivorship. HCLPE has been shown to improve wear properties in midterm outcomes when compared to traditional polyethylene liners; however, there is a paucity of studies evaluating long-term outcomes. In addition, there is concern that wear rates may accelerate as the implant ages. Thus, the aims of this study are to report on the longest-to-date follow-up of a specific first-generation HCLPE liner and to determine whether there is a change in the annual wear rate over time. METHODS:Forty hips in 38 patients which were previously reported on in a midterm study were included in this long-term follow-up study. Patients in this cohort all received total hip arthroplasty between March 1999 and August 2004 using the Crossfire HCLPE liner. Annual wear rates (mm/y) were calculated for this cohort. Patients were contacted and asked about complications or revision procedures they may have had since the index procedure. RESULTS:Clinical follow-up averaged 12.9 years with a range of 7-18 years. The average follow-up duration was 12.5 years with a range of 10-17 years. Linear wear was found to be 0.056 ± 0.036 mm/y. Osteolysis was not observed in any of the patients with greater than 10-year radiographic follow-up. Furthermore, only 1 patient required revision surgery following a mechanical fall. CONCLUSION/CONCLUSIONS:Our study demonstrates the long-term wear rates associated with HCLPE liners continue to match rates published in midterm studies. Previously, we have reported that this cohort had an average annual wear rate of 0.05 mm/y over 10 years. This most recent report demonstrates a similar wear rate with up to 18-year follow-up.

CASE/METHODS:We review the case of a 44-year-old man with Camurati-Engelmann disease, who presented with chronic right hip pain that did not improve following intra-articular hip injections. He was functionally debilitated because of the worsening pain. Routine radiographs demonstrated severe right hip osteoarthritis and severe diaphyseal sclerosis of the femur. To address the narrowed medullary cavity, appropriate reaming of the diaphysis and broaching to fill the metaphysis were performed. The patient underwent an uncemented total hip arthroplasty that resulted in an excellent recovery with no complications. CONCLUSION/CONCLUSIONS:Uncemented total hip arthroplasty serves as a good option for patients with hip osteoarthritis secondary to Camurati-Engelmann disease. Anticipation of potential operative challenges is the key to avoiding complications and achieving an optimal, durable outcome.

Obesity is an epidemic in the health care system. Obesity poses several challenges and raises unique issues for the arthroplasty surgeon. Obese patients are at higher risk for infection and dislocation. Additionally, obese patients have poorer implant survivorship and functional scores postoperatively. Obesity is a modifiable risk factor and weight loss preoperatively should be strongly considered. Obese patients must be counseled so that they have realistic expectations after total joint arthroplasty.

Although bariatric surgery is a proven means of weight loss and treatment of obesity-related comorbidities in morbidly obese patients, it is not yet clear how it affects outcomes after total joint arthroplasty in this high-risk patient population. This article explores the effects of obesity and bariatric surgery on osteoarthritis and total joint arthroplasty, and also discusses the financial and ethical implications of use of bariatric surgery for risk reduction before total joint arthroplasty.

BACKGROUND:Some patients have mid-flexion instability despite stability at 0° and 90° of flexion. This study aims to determine the effects of total knee arthroplasty (TKA) stability while changing femur implant size and position. METHODS:A computational analysis was performed simulating knee flexion of posterior stabilized (PS) and cruciate retaining (CR) TKA designs. Deviations from the ideal TKA implant position were simulated by adjusting tibiofemoral proximal-distal position and femur anterior-posterior position as well as implant size. Forces in ligaments connecting the femur and tibia were collected. Total tibiofemoral ligament load for mid-knee flexion of 15°-75° was analyzed vs proximal-distal implant position, implant size, implant design, and knee flexion for PS and CR knees. Posterior cruciate ligament load was also analyzed for CR knees. RESULTS:Total tibiofemoral ligament load was significantly reduced by a more proximal tibiofemoral and anterior femur position (P < .001). Implant size did not have a significant effect on tibiofemoral ligament load (P > .1). Implant design and knee flexion significantly influenced total tibiofemoral ligament load (P < .001), but the interactions with implant proximal-distal position were not significant (P > .2), indicating that implant proximal-distal position had a similar effect across the 15°-75° knee flexion range for both studied PS and CR implant designs. CONCLUSION/CONCLUSIONS:PS and CR TKA can be well-balanced at 0° and 90° knee flexion and have instability in mid-flexion. Elevating the joint line and shifting the femur anteriorly can cause the knee to be too loose in mid-flexion.

Background/UNASSIGNED:Underweight patients undergoing total hip arthroplasty have been largely overlooked. The purpose of this study was to evaluate their complications profiles compared to normal weight individuals. Methods/UNASSIGNED:Patients were selected from the NSQIP database, matched, and arranged into 2 groups based on BMI. Complications were recorded and analyzed to determine differences in outcomes. Results/UNASSIGNED:Multivariate analysis demonstrated increased length of hospital stay (LOS) (p = 0.006) for underweight patients but failed to demonstrate higher rates of medical or surgical complications. Conclusion/UNASSIGNED:There are no increased rates of infectious or medical complications in underweight patients undergoing THA. However, increased LOS was demonstrated.

BACKGROUND:There is a lack of comparative data on osseointegration (BIC) of acetabular cup surfaces in hip arthroplasty in both normal bone mineral density and in conditions of osteoporosis. AIM/OBJECTIVE:To compare osseointegration of acetabular implants with various types of surfaces in an animal model with normal and osteoporotic bone tissue. MATERIAL AND METHODS/METHODS:The study was performed on 60 rats. To simulate osteoporosis ovariectomy was performed in 30 animals. Thirty healthy rats served as controls. In standardized defects of the distal metadiaphysis of the femur we implanted: porous tantalum Trabecular Metal (A), Trabecular Titanium (B), Titanium with Gription coating (C), Stiktite (D), and Tritanum (E). Bone apposition (osseointegration) was defined as all areas of direct "bone-to-implant contact" (BIC). RESULTS:No qualitative morphological differences in the evaluation of BIC around different implant types was seen in normal rats and rats with osteoporosis. Connective tissue areas around implants were larger in rats with osteoporosis. Morphometric studies showed that the highest BIC were seen in implants A and B, both in healthy animals ([72.00 ± 3.48]% and [67.46 ± 1.69]%) and ones with osteoporosis ([59.19 ± 2.10]% and [53.36 ± 2.57]%). BIC was (60.10 ± 2.05)%, (60.26 ± 2.36)%, and (61.78 ± 2.27)% around implants C, D and E in healthy rats, respectively. BIC in osteoporosis was (45.39 ± 2.37)%, (47.81 ± 2.41)% and (42.10 ± 1.44)%, respectively. CONCLUSION/CONCLUSIONS:Our study showed that the evaluated implants have good BIC features. Furthermore, based on histomorthometry and histology, Porous tantalum Trabecular Metal (A) and Trabecular Titanium (B) implants exhibit higher BIC with bone tissue.

BACKGROUND:Hospital length of stay is a major driver of cost in the total hip arthroplasty (THA) episode of care, and as a result, significant efforts are being made to minimize it. This study aims to assess the utility of the Outpatient Arthroplasty Risk Assessment (OARA) screening tool in accurately identifying patients for safe and early discharge after THA. METHODS:A retrospective review was conducted on 332 consecutive patients who underwent primary THA at a single tertiary academic center. Patients were evaluated using the OARA score, a tool that has been proposed to identify patients who can safely undergo early discharge after THA. The validity of these claims was assessed by analyzing the OARA score's positive and negative predictive values for high vs low OARA scores between patients enrolled in our (1) same-day discharge (SDD) and 2) next-day discharge (NDD) pathways. RESULTS:When comparing the utility of the OARA score in accurately predicting length of stay, the OARA score demonstrated a (1) higher, but constant, positive predictive value for discharge on postoperative day (POD) 0 for SDD (86.1%) than POD1 for NDD (35.5%) and (2) lower negative predictive value for discharge on POD0 (23.1%) for SDD than POD1 for NDD (86.1%). CONCLUSION/CONCLUSIONS:The OARA score was developed to risk-stratify patients who can safely undergo SDD or NDD after THA. In this study, the OARA score was a highly predictive tool in identifying NDD patients at risk for failure of discharge by POD1.

One-stage and two-stage revision strategies are the two main options for treating established chronic peri-prosthetic joint infection (PJI) of the hip; however, there is uncertainty regarding which is the best treatment option. We aimed to compare the risk of re-infection between the two revision strategies using pooled individual participant data (IPD). Observational cohort studies with PJI of the hip treated exclusively by one- or two-stage revision and reporting re-infection outcomes were retrieved by searching MEDLINE, EMBASE, Web of Science, The Cochrane Library, and the WHO International Clinical Trials Registry Platform; as well as email contact with investigators. We analysed IPD of 1856 participants with PJI of the hip from 44 cohorts across four continents. The primary outcome was re-infection (recurrence of infection by the same organism(s) and/or re-infection with a new organism(s)). Hazard ratios (HRs) for re-infection were calculated using Cox proportional frailty hazards models. After a median follow-up of 3.7 years, 222 re-infections were recorded. Re-infection rates per 1000 person-years of follow-up were 16.8 (95% CI 13.6-20.7) and 32.3 (95% CI 27.3-38.3) for one-stage and two-stage strategies respectively. The age- and sex-adjusted HR of re-infection for two-stage revision was 1.70 (0.58-5.00) when compared with one-stage revision. The association remained consistently absent after further adjustment for potential confounders. The HRs did not vary importantly in clinically relevant subgroups. Analysis of pooled individual patient data suggest that a one-stage revision strategy may be as effective as a two-stage revision strategy in treating PJI of the hip.

BACKGROUND:At our institution, all postoperative total hip arthroplasty (THA) candidates have received home health services (HHS), consisting of visiting nurses, physical and occupational therapists. However, with a more technologically inclined patient population, electronic patient rehabilitation applications (EPRAs) can be used to deliver perioperative care at the comfort of the patient's home. The aim of this study is to investigate the clinical utility and economic burden associated with digital rehabilitation applications in primary THA recipients. METHODS:We conducted a single-center, retrospective review of patients operated between November 2016 and November 2017. Before surgery, and at the discretion of the surgeon, patients were assigned to EPRA with HHS or EPRA alone. Patient baseline demographics, EPRA engagement, and validated patient-reported outcomes (PROs) were (Veterans Rand 12-Item Health Survey [VR-12] and Hip Disability and Osteoarthritis Outcome Score Junior) at baseline and 12 weeks. These PRO scores were correlated with cohort assignments to assess noninferiority of EPRA alone. RESULTS:In total, 268 patients received either EPRA-HHS (n = 169) or EPRA (n = 99) alone. Patients receiving EPRA only were on average younger (60.8 vs 65.8; P < .0001), but otherwise similar to patients in the EPRA-HHS cohort. EPRA-only patients demonstrated no differences in VR-12 (P > .05) and Hip Disability and Osteoarthritis Outcome Score Junior (P > .05) when compared with EPRA-HHS. CONCLUSION/CONCLUSIONS:The integration of electronic rehabilitation tools is gaining acceptance within the orthopedic community. Our study demonstrated that EPRA alone was clinically noninferior while substantially less costly than EPRA-HHS.