Abdel, Matthew P.

Background: Osteonecrosis of the hip is the underlying etiology for 3% to 12% of total hip arthroplasties (THAs). Compared with patients who undergo THA because of osteoarthritis, those who do so because of osteonecrosis typically are younger, have a greater number of underlying diagnoses, and have inferior clinical outcomes and implant survivorship. The purpose of this study was to compare the long-term implant survivorship (median follow-up, 10 years), functional outcomes, and radiographic results of contemporary THAs with a highly cross-linked polyethylene (HXLPE) liner between patients with osteonecrosis and those with osteoarthritis. Methods: All patients who underwent primary THA with an HXLPE liner from 1999 to 2007 were identified from our institutional total joint registry. Patients with a primary diagnosis of osteonecrosis were matched 1:1, on the basis of age, sex, and body mass index (BMI), to patients with a diagnosis of osteoarthritis. This resulted in 461 hips in 413 patients with osteonecrosis matched to 461 hips in 427 patients with osteoarthritis (mean age, 59 years; 47% female; and mean BMI, 29 kg/m 2 ). Long-term implant survivorship, patient-reported outcomes, and radiographic findings were compared. In addition, a subgroup analysis of the osteonecrosis group was performed to see whether certain underlying etiologies portended poor outcomes. The median follow-up was 10 years. Results: The 15-year cumulative rates of revision were 6.6% and 4.5% in the osteonecrosis and osteoarthritis groups, respectively (hazard ratio [HR] = 1.8, p = 0.09). The 15-year cumulative rates of any reoperation were 10.5% and 6.4% in the osteonecrosis and osteoarthritis groups, respectively (HR = 2.2, p = 0.008). There were no radiographic signs of component loosening or osteolysis in the entire cohort. Despite a lower median preoperative Harris hip score (HHS) for patients with osteonecrosis, both groups had marked improvements in their scores, which were similar at all time points after surgery. The cumulative rate of reoperations at 15 years was 0% for hips with radiation-induced osteonecrosis, 6.3% for those with alcohol-induced osteonecrosis, 9.0% for those with posttraumatic osteonecrosis, 12.1% for those with steroid-induced osteonecrosis, and 25% for those with idiopathic osteonecrosis. Conclusions: Contemporary THA with an HXLPE liner offers excellent long-term implant survivorship and functional outcomes for patients with osteonecrosis; however, the risk of a reoperation is higher when compared with patients with osteoarthritis. Level of Evidence: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

AbstractFor patients who qualify, simultaneous bilateral total knee arthroplasty (TKA) is a viable option for the treatment of bilateral symptoms. However, the incidence of chronic obstructive pulmonary disease (COPD) has been steadily rising over the past few decades and may impact those who qualify as candidates for bilateral TKA. As such, the aim of this study was to determine the impact of COPD on postoperative outcomes in patients who receive simultaneous bilateral TKA. A retrospective cohort study was conducted utilizing data provided through the American College of Surgeons National Surgical Quality Improvement Program. All patients who had undergone simultaneous bilateral TKA between 2007 and 2016 were identified and further stratified into groups based upon the COPD status. Incidence of adverse events after TKA in the acute postoperative period was evaluated with univariate and multivariate analyses. COPD was found to be an independent risk factor for the development of major (odds ratio [OR]: 2.5; p = 0.015), renal (OR: 5.1; p = 0.02), and thromboembolic complications (OR: 2.5; p = 0.027). In addition, patients with COPD were at increased risk for having an extended hospital length of stay (LOS; p < 0.001) and development of urinary tract infections (p < 0.001). Patients with COPD are at higher risk for development of overall major complications, as well as renal and thromboembolic complications after simultaneous bilateral TKA. Interestingly, patients were not at increased risk for the development of pulmonary or wound complications. When considering a staged versus simultaneous bilateral TKA, surgeons should be aware of the impact COPD status has on the postoperative complication rate.

The in vitro activities of rifampin, rifabutin, rifapentine, and rifaximin were tested against 200 periprosthetic joint infection (PJI)-associated staphylococci. Seven rifampin-resistant isolates had MICs of ≥4 μg/ml. Three isolates had rifampin MICs of 0.25 to 1 μg/ml and harbored an Asp471Gly RpoB variant, suggesting that the CLSI rifampin-susceptible staphylococcal breakpoint of ≤1 μg/ml may be too high.

ABSTRACTArthrofibrosis is a common complication following total knee arthroplasty caused by pathologic fibroblast activation and excessive collagen deposition around a synovial joint leading to debilitating loss of motion. Treatment options are limited because the pathologic mechanisms remain to be characterized. Dysregulation of the inflammatory cascade may lead to communication between myofibroblasts and immune cells triggering tissue metaplasia, and excessive collagen deposition described clinically as arthrofibrosis. We explored the novel use of celecoxib (selective cyclooxygenase‐2 [COX‐2] inhibitor) to disrupt the downstream effects of the post‐traumatic inflammatory cascade and inhibit scar tissue formation in a validated rabbit model of arthrofibrosis combined with new parameters for quantifying the stiffness of the posterior capsule. Biomechanical and molecular analyses, of contracted rabbit knee posterior capsule tissue after COX‐2 inhibition revealed increased maximal passive extension and down‐regulation of collagen messenger RNA compared with controls. Histopathologic examination suggested a trend of decreased quantities of dense fibrous connective tissue with COX‐2 inhibition. These data may suggest that inhibiting the inflammatory cascade could potentially reduce pathologic myofibroblast activation, thereby reducing scar tissue formation and increasing the range of motion in arthrofibrotic joints. Implementing a multi‐modal pharmacologic approach may simultaneously target numerous cellular components contributing to the complex process of arthrofibrogenesis. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2609–2620, 2019

Background: Stiffness is a common reason for suboptimal clinical outcomes after primary total knee arthroplasty (pTKA). There is a lack of consensus regarding its definition, which is often conflated with its histopathologic subcategory—i.e., arthrofibrosis. There is value in refining the definition of acquired idiopathic stiffness in an effort to select for patients with arthrofibrosis. We conducted a systematic review and meta-analysis to establish a consensus definition of acquired idiopathic stiffness, determine its prevalence after pTKA, and identify potential risk factors for its development. Methods: MEDLINE, Embase, Cochrane Controlled Register of Trials (CENTRAL), and Scopus databases were searched from 2002 to 2017. Studies that included patients with stiffness after pTKA were screened with strict inclusion and exclusion criteria to isolate the subset of patients with acquired idiopathic stiffness unrelated to known extrinsic or surgical causes. Three authors independently assessed study eligibility and risk of bias and collected data. Outcomes of interest were then analyzed according to age, sex, and body mass index (BMI). Results: In the 35 included studies (48,873 pTKAs), the mean patient age was 66 years. In 63% of the studies, stiffness was defined as a range of motion of <90° or a flexion contracture of >5° at 6 to 12 weeks postoperatively. The prevalence of acquired idiopathic stiffness after pTKA was 4%, and this did not differ according to age (4%, I 2 = 95%, among patients <65 years old and 5%, I 2 = 96%, among those ≥65 years old; p = 0.238). The prevalence of acquired idiopathic stiffness was significantly lower in males (1%, I 2 = 85%) than females (3%, I 2 = 95%) (p < 0.0001) as well as in patients with a BMI of <30 kg/m 2 (2%, I 2 = 94%) compared with those with a BMI of ≥30 kg/m 2 (5%, I 2 = 97%) (p = 0.027). Conclusions: Contemporary literature supports the following definition for acquired idiopathic stiffness: a range of motion of <90° persisting for >12 weeks after pTKA in patients in the absence of complicating factors including preexisting stiffness. The mean prevalence of acquired idiopathic stiffness after pTKA was 4%; females and obese patients were at increased risk. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Background: Povidone-iodine (PI) irrigation is often used prior to wound closure in total joint arthroplasty, but there are limited reports evaluating its efficacy in decreasing joint infections. The goal of this study was to compare the rate of any reoperation for infection (both superficial and deep) in primary total hip arthroplasty (THA) and primary total knee arthroplasty (TKA) among patients who did and did not receive PI irrigation prior to wound closure. Methods: Using our institution’s total joint registry, we identified 5,534 primary THA and 6,204 primary TKA procedures performed from 2013 to 2017. Cases were grouped on the basis of whether or not the wound was irrigated with 1 L of 0.25% PI prior to closure. PI irrigation was used in 1,322 (24%) of the THA cases and in 2,410 (39%) of the TKA cases. The rates of reoperation for infection at 3 months and 1 year were compared between the 2 groups. The same comparisons were then performed using propensity scores to account for differences in baseline characteristics. Results: The rate of reoperation for infection as assessed at 3 months following THA was similar between those who received dilute PI irrigation (0.9%) and who did not (0.7%) (p = 0.7). At 1 year, the rate of reoperation for infection was similar between those who received dilute PI irrigation (0.7%) and those who did not (0.9%) (p = 0.6). After using the propensity score, there was no difference between the groups in the risk of septic reoperations. For TKA, the rate of reoperation as assessed at 3 months was similar between those who received dilute PI irrigation (0.8%) and those who did not (0.3%) (p = 0.06). At 1 year, there was a greater rate of reoperations for infection among those who received dilute PI irrigation (1.2%) compared with those who did not (0.6%) (p = 0.03). However, there was no difference in the risk of septic reoperations between the groups after using the propensity score. Conclusions: Despite enthusiasm for and progressive adoption of the use of dilute PI irrigation at our institution, there was not a significant reduction in the risk of reoperation for infection as assessed at 3 months and 1 year following primary THA and TKA. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Background: Postoperative infection remains a major challenge in revision total hip arthroplasty (THA) and revision total knee arthroplasty (TKA). Wound irrigation with dilute povidone-iodine (PI) solution has emerged as a simple, inexpensive, and potentially successful means of reducing postoperative infections. The aim of this study was to assess its effectiveness in reducing infection following revision THA and TKA in, to our knowledge, the largest revision cohort to date. Methods: Using our institution’s total joint registry, we identified 1,402 revision THAs and 1,482 revision TKAs performed during the study period (2013, when the PI irrigation protocol was first implemented, to 2017). The PI lavage protocol was employed in 27% of the revision THA cases and 34% of the revision TKA cases; in the remaining cases, the protocol was not used. Demographics, comorbid conditions, underlying surgical diagnoses, and whether the revision was for a septic or an aseptic etiology were compared between the groups (use or no use of PI irrigation). Any reoperation due to infection, as assessed at 3 and 12 months following revision arthroplasty, was compared between the groups and propensity scores were calculated to account for differences in baseline characteristics between the groups. Results: After adjusting for baseline differences between the groups using the propensity-score weighted models, we found no significant difference in the rate of reoperation for infection at 3 months (p = 0.58 for revision THA, and p = 0.06 for revision TKA) and at 12 months (p = 0.78 for revision THA, and p = 0.06 for revision TKA). Nonetheless, the hazard ratios from the propensity-score model trended higher for patients who received PI lavage: 1.6 and 1.3 for revision THA at 3 and 12 months, respectively, and 2.9 at both 3 and 12 months for revision TKA. Conclusions: PI wound lavage demonstrated no benefit in reducing any reoperation for infection following revision THA and TKA. Moreover, the trend toward higher rates for reoperation for infection among patients who received PI irrigation merit further consideration. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Aims Tranexamic acid (TXA) is proven to reduce blood loss following total knee arthroplasty (TKA), but there are limited data on the impact of similar dosing regimens in revision TKA. The purpose of this multicentre randomized clinical trial was to determine the optimal regimen to maximize the blood-sparing properties of TXA in revision TKA. Patients and Methods From six-centres, 233 revision TKAs were randomized to one of four regimens: 1 g of intravenous (IV) TXA given prior to the skin incision, a double-dose regimen of 1 g IV TXA given both prior to skin incision and at time of wound closure, a combination of 1 g IV TXA given prior to skin incision and 1 g of intraoperative topical TXA, or three doses of 1950 mg oral TXA given two hours preoperatively, six hours postoperatively, and on the morning of postoperative day one. Randomization was performed based on the type of revision procedure to ensure equivalent distribution among groups. Power analysis determined that 40 patients per group were necessary to identify a 1 g/dl difference in the reduction of haemoglobin postoperatively between groups with an alpha of 0.05 and power of 0.80. Per-protocol analysis involved regression analysis and two one-sided t-tests for equivalence. Results In total, one patient withdrew, five did not undergo surgery, 16 were screening failures, and 25 did not receive the assigned treatment, leaving 186 patients for analysis. There was no significant difference in haemoglobin reduction among treatments (2.8 g/dl for single-dose IV TXA, 2.6 g/dl for double-dose IV TXA, 2.6 g/dl for combined IV/topical TXA, 2.9 g/dl for oral TXA; p = 0.38). Similarly, calculated blood loss (p = 0.65) and transfusion rates (p = 0.95) were not significantly different between groups. Equivalence testing assuming a 1 g/dl difference in haemoglobin change as clinically relevant showed that all possible pairings were statistically equivalent. Conclusion Despite the higher risk of blood loss in revision TKA, all TXA regimens tested had equivalent blood-sparing properties. Surgeons should consider using the lowest effective dose and least costly TXA regimen in revision TKA. Cite this article: Bone Joint J 2019;101-B(Supple 7):10–16

Aims While previously underappreciated, factors related to the spine contribute substantially to the risk of dislocation following total hip arthroplasty (THA). These factors must be taken into consideration during preoperative planning for revision THA due to recurrent instability. We developed a protocol to assess the functional position of the spine, the significance of these findings, and how to address different pathologies at the time of revision THA. Patients and Methods Prospectively collected data on 111 patients undergoing revision THA for recurrent instability from January 2014 to January 2017 at two institutions were included (protocol group) and matched 1:1 to 111 revisions specifically performed for instability not using this protocol (control group). Mean follow-up was 2.8 years. Protocol patients underwent standardized preoperative imaging including supine and standing anteroposterior (AP) pelvis and lateral radiographs. Each case was scored according to the Hip-Spine Classification in Revision THA. Results Survival free of dislocation at two years was 97% in the protocol group (three dislocations, all within three months of surgery) versus 84% in the control group (18 patients). Furthermore, 77% of the inappropriately positioned acetabular components would have been unrecognized by supine AP pelvis imaging alone. Conclusion Using the Hip-Spine Classification System in revision THA, we demonstrated a significant decrease in the risk of recurrent instability compared with a control group. Without the use of this algorithm, 77% of inappropriately positioned acetabular components would have been unrecognized and incorrect treatment may have been instituted. Cite this article: Bone Joint J 2019;101-B:817–823.

Aims The aims of this study were to compare the mean duration of antibiotic release and the mean zone of inhibition between vancomycin-loaded porous tantalum cylinders and antibiotic-loaded bone cement at intervals, and to evaluate potential intrinsic antimicrobial properties of tantalum in an in vitro medium environment against methicillin-sensitive Staphylococcus aureus (MSSA). Materials and Methods Ten porous tantalum cylinders and ten cylinders of cement were used. The tantalum cylinders were impregnated with vancomycin, which was also added during preparation of the cylinders of cement. The cylinders were then placed on agar plates inoculated with MSSA. The diameter of the inhibition zone was measured each day, and the cylinders were transferred to a new inoculated plate. Inhibition zones were measured with a Vernier caliper and using an automated computed evaluation, and the intra- and interobserver reproducibility were measured. The mean inhibition zones between the two groups were compared with Wilcoxon’s test. Results MSSA was inhibited for 12 days by the tantalum cylinders and for nine days by the cement cylinders. At day one, the mean zone of inhibition was 28.6 mm for the tantalum and 19.8 mm for the cement group (p < 0.001). At day ten, the mean zone of inhibition was 3.8 mm for the tantalum and 0 mm for the cement group (p < 0.001). The porous tantalum cylinders soaked only with phosphate buffered solution showed no zone of inhibition. Conclusion Compared with cement, tantalum could release antibiotics for longer. Further studies should assess the advantages of using antibiotic-loaded porous tantalum implants at revision arthroplasty. Cite this article: Bone Joint J 2019;101-B:848–851.