Citations

ABSTRACTThe current method of measuring arthrofibrosis in live rabbits is critically limited. Specifically, this method involves radioactive fluoroscopy, error‐prone goniometric measurements, and static joint angle outcomes that fail to approximate the compliance of tissues surrounding the joint. This study aims to validate a novel method of capturing the compliance of contracted tissues surrounding the joint without the use of fluoroscopy or animal sacrifice. Surgically induced contractures of one‐hundred and eight rabbits were measured using the current standard of contracture measurement (a pulley system) as well as a newly designed dynamic load cell (DLC) device. The DLC device was highly reliable when compared to the pulley system (r = 0.907, p < 0.001). Finally, the DLC device produced joint stiffness hysteresis curves capable of approximating the compliance of stiff joint tissues, ultimately calculating a mean joint stiffness of 1.57 ± 1.31 N · m · rad−1 (range, 0.33–6.37 N · m · rad−1). In conclusion, the DLC device represents a valid method for measuring joint contractures. Further, the DLC device notably improves current techniques by introducing the capacity to approximate the compliance of contracted tissues in living rabbits. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2186–2192, 2018.

Abstract Background Long-term mortality after primary THA is lower than in the general population, but it is unknown whether this is also true after revision THA. Questions/Purposes We examined (1) long-term mortality according to reasons for revision after revision THA, and (2) relative mortality trends by age at surgery, years since surgery, and calendar year of surgery. Methods This retrospective study included 5417 revision THAs performed in 4532 patients at a tertiary center between 1969 and 2011. Revision THAs were grouped by surgical indication in three categories: periprosthetic joint infections (938; 17%); fractures (646; 12%); and loosening, bearing wear, or dislocation (3833; 71%). Patients were followed up until death or December 31, 2016. The observed number of deaths in the revision THA cohort was compared with the expected number of deaths using standardized mortality ratios (SMRs) and Poisson regression models. The expected number of deaths was calculated assuming that the study cohort had the same calendar year, age, and sex-specific mortality rates as the United States general population. Results The overall age- and sex-adjusted mortality was slightly higher than the general population mortality (SMR, 1.09; 95% CI, 1.05-1.13; p < 0.001). There were significant differences across the three surgical indication subgroups. Compared with the general population mortality, patients who underwent revision THA for infection (SMR, 1.35; 95% CI, 1.24-1.48; p < 0.001) and fractures (SMR, 1.23; 95% CI, 1.11-1.37; p < 0.001) had significantly increased risk of death. Patients who underwent revision THA for aseptic loosening, wear, or dislocation had a mortality risk similar to that of the general population (SMR, 1.01; 95% CI, 0.96-1.06; p = 0.647). The relative mortality risk was highest in younger patients and declined with increasing age at surgery. Although the relative mortality risk among patients with aseptic indications was lower than that of the general population during the first year of surgery, the risk increased with time and got worse than that of the general population after approximately 8 to 10 years after surgery. Relative mortality risk improved with time after revision THA for aseptic loosening, wear, or dislocation. Conclusions Shifting mortality patterns several years after surgery and the excess mortality after revision THA for periprosthetic joint infections and fractures reinforce the need for long-term followup, not only for implant survival but overall health of patients having THA. Level of Evidence Level III, therapeutic study

Background: There are conflicting data on the results of irrigation and debridement with component retention in patients with acute periprosthetic hip infections. The goals of this study were to examine contemporary results of irrigation and debridement with component retention for acute infection after primary hip arthroplasty and to identify host, organism, antibiotic, or implant factors that predict success or failure. Methods: Ninety hips (57 total hip arthroplasties and 33 hemiarthroplasties) were diagnosed with acute periprosthetic hip infection (using strict criteria) and were treated with irrigation and debridement and component retention between 2000 and 2012. The mean follow-up was 6 years. Patients were stratified on the basis of McPherson criteria. Hips were managed with irrigation and debridement and retention of well-fixed implants with modular head and liner exchange (70%) or irrigation and debridement alone (30%). Seventy-seven percent of patients were treated with chronic antibiotic suppression. Failure was defined as failure to eradicate infection, characterized by a wound fistula, drainage, intolerable pain, or infection recurrence caused by the same organism strain; subsequent removal of any component for infection; unplanned second wound debridement for ongoing deep infection; and/or occurrence of periprosthetic joint infection-related mortality. Results: Treatment failure occurred in 17% (15 of 90 hips), with component removal secondary to recurrent infection in 10% (9 of 90 hips). Treatment failure occurred in 15% (10 of 66 hips) after early postoperative infection and 21% (5 of 24 hips) after acute hematogenous infection (p = 0.7). Patients with McPherson host grade A had a treatment failure rate of 8%, compared with 16% (p = 0.04) in host grade B and 44% in host grade C (p = 0.006). Most treatment failures (12 of 15 failures) occurred within the initial 6 weeks of treatment; failures subsequent to 6 weeks occurred in 3% of those treated with chronic antibiotic suppression compared with 11% of those who were not treated with suppression (hazard ratio, 4.0; p = 0.3). Conclusions: The success rate was higher in this contemporary series than in many previous series. Systemic host grade A was predictive of treatment success. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Advances in polyethylene (PE) in total hip arthroplasty have led to interest and increased use of highly crosslinked PE (HXLPE) in total knee arthroplasty (TKA). Biomechanical data suggest improved wear characteristics for HXLPE inserts over conventional PE in TKA. Short-term results from registry data and few clinical trials are promising. Our aim is to present a review of the history of HXLPEs, the use of HXLPE inserts in TKA, concerns regarding potential mechanical complications, and a thorough review of the available biomechanical and clinical data.Cite this article: Bone Joint J 2017;99-B:996–1002.

Background: Modular fluted tapered stems have become the most commonly employed category of femoral component in revision hip arthroplasty in North America as a result of favorable early results and simplicity of use. Despite wide adoption, the majority of published data are limited to relatively small series with modest follow-up. The goal of the current study was to determine the success rate and factors associated with success, failure, and complications of the use of modular fluted tapered stems in aseptic revision total hip arthroplasties (THAs) in a large patient cohort. Methods: We identified 519 aseptic femoral revisions during which a modular fluted tapered stem was utilized. Clinical outcomes, Kaplan-Meier survivorship, radiographic outcomes, and complications were assessed. The mean age at revision arthroplasty was 70 years, the mean body mass index (BMI) was 29 kg/m 2 , and the mean duration of follow-up was 4.5 years (range, 2 to 14 years). Results: The mean Harris hip score (HHS) improved significantly from 51 points preoperatively to 76 points at 2 years (p < 0.001). This improvement was maintained at the last follow-up evaluation (mean HHS = 75 points). At the time of the most recent follow-up, 16 femoral revisions had been performed: 6 because of aseptic loosening, 4 because of infection, 3 because of instability, 2 because of periprosthetic fracture, and 1 because of stem fracture. The 10-year survivorship was 96% with revision for any reason as the end point and 90% with any reoperation as the end point. Of the patients who were alive and had not undergone revision at the time of final follow-up, 12 had stem subsidence but all but 1 of these stems had stabilized after subsiding. Postoperative complications were noted in 12% of the cases. Repeat revision due to femoral component loosening was not correlated with the preoperative bone-loss category or patient demographic factors. Conclusions: In this large series, femoral revision with a modular fluted tapered stem provided a high rate of osseointegration and sustained improvement in clinical scores at the time of the last follow-up. There was also a high rate of successful implant fixation across all categories of preoperative bone loss and an acceptable rate of complications. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Background: Pelvic discontinuity is uncommon and presents the surgeon with complex reconstructive challenges. The objective of this study is to report the results of current strategies used in the treatment of pelvic discontinuity. Methods: We retrospectively analyzed prospectively collected data on 113 consecutive revision total hip arthroplasties performed for the treatment of unilateral pelvic discontinuity at a single institution. The study included 18 male and 95 female patients with a mean age of 63 years at the time of revision surgery. Preoperative, immediate postoperative, and latest follow-up radiographs were reviewed to assess healing of the discontinuity as well as acetabular component stability. Treatment modalities included an uncemented cup with a posterior column plate (50 hips; 44%), a cup-cage construct (27 hips; 24%), an antiprotrusio cage with or without a posterior column plate (26 hips; 23%), and an uncemented cup alone (10 hips; 9%). The average duration of follow-up for each of these types of surgical reconstruction was similar (range, 3.9 to 7.2 years). Results: Five-year revision-free survivorship of the implant was best with a cup-cage construct (100%) and worst with an uncemented cup with a posterior column plate (80%) and a cup alone (80%). Healing of the discontinuity was achieved in 50% of the hips with an uncemented cup alone, 74% of the hips with an uncemented cup and a posterior column plate, 74% of the hips with a cup-cage construct, and 88% of the hips with an antiprotrusio cage construct (91% of these hips when structural allograft was used). The overall complication rate was 26.5%. The average Harris hip score improved from 54 preoperatively to 69 postoperatively (95% confidence interval: 50 to 57 preoperatively and 65 to 72 postoperatively; p = 0.017). Conclusions: Improved survivorship and healing rates were seen in this series when a reconstruction cage was used as an adjunct to an uncemented cup (cup-cage) or in combination with structural allograft bone that bridged the discontinuity. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Background: A potential cause of persistent groin pain after total hip arthroplasty is impingement of the iliopsoas tendon. Treatment options include conservative management, tenotomy, and acetabular revision, but the literature, to our knowledge, has been limited to small case series on each technique. We present a series of patients with iliopsoas impingement after total hip arthroplasty and evaluate efficacy and risk factors for success or failure of each treatment strategy. Methods: Forty-nine patients treated at one institution for a diagnosis of iliopsoas impingement after primary total hip arthroplasty with hemispherical acetabular component and polyethylene bearing were retrospectively reviewed. Twenty-one patients underwent acetabular revision, 8 patients underwent tenotomy, and 20 patients had nonoperative management. The mean follow-up was 4 years. Anterior acetabular component prominence was measured on true lateral hip radiographs. Results: At the most recent follow-up, 10 patients (50%) in the nonoperative group had groin pain resolution compared with 22 patients (76%) in the operative group (p = 0.06). In patients with <8 mm of component prominence, tenotomy provided resolution of groin pain in 5 (100%) of 5 patients and a mean Harris hip score of 89 points. In patients with ≥8 mm of prominence, acetabular revision led to groin pain resolution in 12 (92%) of 13 patients compared with 1 (33%) of 3 patients treated with tenotomy (p = 0.07). Conclusions: Nonoperative management of iliopsoas impingement led to groin pain resolution in 50% of patients. In patients with minimal acetabular component prominence, iliopsoas release provided a high rate of success. Acetabular revision was more predictable for groin pain resolution in patients with ≥8 mm of anterior component prominence. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Background: Despite the large increase in total hip arthroplasties and total knee arthroplasties, the incidence and prevalence of additional contralateral or ipsilateral joint arthroplasty are poorly understood. The purpose of this study was to determine the rate of additional joint arthroplasty after a primary total hip arthroplasty or total knee arthroplasty. Methods: This historical cohort study identified population-based cohorts of patients who underwent primary total hip arthroplasty (n = 1,933) or total knee arthroplasty (n = 2,139) between 1969 and 2008. Patients underwent passive follow-up through their medical records beginning with the primary total hip arthroplasty or total knee arthroplasty. We assessed the likelihood of undergoing a subsequent total joint arthroplasty, including simultaneous and staged bilateral procedures. Age, sex, and calendar year were evaluated as potential predictors of subsequent arthroplasty. Results: During a mean follow-up of 12 years after an initial total hip arthroplasty, we observed 422 contralateral total hip arthroplasties (29% at 20 years), 76 contralateral total knee arthroplasties (6% at 10 years), and 32 ipsilateral total knee arthroplasties (2% at 20 years). Younger age was a significant predictor of contralateral total hip arthroplasty (p < 0.0001), but not a predictor of the subsequent risk of total knee arthroplasty. During a mean follow-up of 11 years after an initial total knee arthroplasty, we observed 809 contralateral total knee arthroplasties (45% at 20 years), 31 contralateral total hip arthroplasties (3% at 20 years), and 29 ipsilateral total hip arthroplasties (2% at 20 years). Older age was a significant predictor of ipsilateral or contralateral total hip arthroplasty (p < 0.001). Conclusions: Patients undergoing total hip arthroplasty or total knee arthroplasty can be informed of a 30% to 45% chance of a surgical procedure in a contralateral cognate joint and about a 5% chance of a surgical procedure in noncognate joints within 20 years of initial arthroplasty. Increased risk of contralateral total knee arthroplasty following an initial total hip arthroplasty may be due to gait changes prior to and/or following total hip arthroplasty. The higher prevalence of bilateral total hip arthroplasty in younger patients may result from bilateral disease processes that selectively affect the young hip, such as osteonecrosis, or structural hip problems, such as acetabular dysplasia or femoroacetabular impingement. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Aims To demonstrate, with concrete examples, the value of in-depth exploration and comparison of data published in National Joint Arthroplasty registry reports. Patients and Methods The author reviewed published current reports of National Joint Arthroplasty registries for findings of current significance to current orthopaedic practice. Results A total of six observations that demonstrate actionable or unexpected findings from joint registries are described. These include: one third to one half of all arthroplasty failures in the first decade occur in the first one to two years; infection rates after arthroplasty have not declined in the last three decades; infection after TKA is more common in men than women; outcomes of TKA are more variable in young compared with older patients; new technologies (uncemented implants and crosslinked polyethylene) have improved results of THA and a real-time shift in use of ceramic femoral heads is occurring in THA. Conclusion These six observations may be used to better understand current practice, stimulate practice improvements or suggest topics for further study. Cite this article: Bone Joint J 2017;99-B(1 Supple A):3–7

Background: High body mass index (BMI) is associated with increased rates of complications after total knee arthroplasty. To date, to our knowledge, studies have examined risk as a dichotomous variable using specific BMI thresholds. The purpose of this investigation was to quantify implant survival and the risk of common complications after total knee arthroplasty using BMI as a continuous variable. Methods: Using prospectively collected data from our institutional total joint registry, we analyzed 22,289 consecutive knees, in 16,136 patients, treated with primary total knee arthroplasty from 1985 to 2012. The mean BMI of these patients at the time of the surgical procedure was 31.3 kg/m 2 (range, 11 to 69 kg/m 2 ). The Kaplan-Meier survival method was used to estimate survivorship, reoperations, and common complications, with associations of outcomes assessed using a Cox regression model. Results: Utilizing smoothing spline parameterization, we found that reoperation (p < 0.001) and implant revision or removal rates (p < 0.001) increased with increasing BMI after total knee arthroplasty. Increasing BMI also was associated with increased rates of wound infection (hazard ratio [HR], 1.07; p < 0.001) and deep infection (HR, 1.08; p < 0.001) per unit of BMI over 35 kg/m 2 . A BMI of 35 to 40 kg/m 2 was associated with a higher rate of implant revision for aseptic loosening (p < 0.001) and for polyethylene wear (p < 0.001) compared with a BMI of 18 to 24.99 kg/m 2 . There was no correlation between BMI and risk of venous thromboembolism, tibiofemoral instability, or need for knee manipulation. Conclusions: The rates of reoperation, implant revision or removal, and many common complications after total knee arthroplasty were strongly associated with BMI. Level of Evidence: Prognostic Level IV . See Instructions for Authors for a complete description of levels of evidence.