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Background: Estimating the risk of revision after arthroplasty could inform patient and surgeon decision-making. However, there is a lack of well-performing prediction models assisting in this task, which may be due to current conventional modeling approaches such as traditional survivorship estimators (such as Kaplan-Meier) or competing risk estimators. Recent advances in machine learning survival analysis might improve decision support tools in this setting. Therefore, this study aimed to assess the performance of machine learning compared with that of conventional modeling to predict revision after arthroplasty., Question/purpose: Does machine learning perform better than traditional regression models for estimating the risk of revision for patients undergoing hip or knee arthroplasty?, Methods: Eleven datasets from published studies from the Dutch Arthroplasty Register reporting on factors associated with revision or survival after partial or total knee and hip arthroplasty between 2018 and 2022 were included in our study. The 11 datasets were observational registry studies, with a sample size ranging from 3038 to 218,214 procedures. We developed a set of time-to-event models for each dataset, leading to 11 comparisons. A set of predictors (factors associated with revision surgery) was identified based on the variables that were selected in the included studies. We assessed the predictive performance of two state-of-the-art statistical time-to-event models for 1-, 2-, and 3-year follow-up: a Fine and Gray model (which models the cumulative incidence of revision) and a cause-specific Cox model (which models the hazard of revision). These were compared with a machine-learning approach (a random survival forest model, which is a decision tree-based machine-learning algorithm for time-to-event analysis). Performance was assessed according to discriminative ability (time-dependent area under the receiver operating curve), calibration (slope and intercept), and overall prediction error (scaled Brier score). Discrimination, known as the area under the receiver operating characteristic curve, measures the model's ability to distinguish patients who achieved the outcomes from those who did not and ranges from 0.5 to 1.0, with 1.0 indicating the highest discrimination score and 0.50 the lowest. Calibration plots the predicted versus the observed probabilities; a perfect plot has an intercept of 0 and a slope of 1. The Brier score calculates a composite of discrimination and calibration, with 0 indicating perfect prediction and 1 the poorest. A scaled version of the Brier score, 1 - (model Brier score/null model Brier score), can be interpreted as the amount of overall prediction error., Results: Using machine learning survivorship analysis, we found no differences between the competing risks estimator and traditional regression models for patients undergoing arthroplasty in terms of discriminative ability (patients who received a revision compared with those who did not). We found no consistent differences between the validated performance (time-dependent area under the receiver operating characteristic curve) of different modeling approaches because these values ranged between -0.04 and 0.03 across the 11 datasets (the time-dependent area under the receiver operating characteristic curve of the models across 11 datasets ranged between 0.52 to 0.68). In addition, the calibration metrics and scaled Brier scores produced comparable estimates, showing no advantage of machine learning over traditional regression models., Conclusion: Machine learning did not outperform traditional regression models., Clinical Relevance: Neither machine learning modeling nor traditional regression methods were sufficiently accurate in order to offer prognostic information when predicting revision arthroplasty. The benefit of these modeling approaches may be limited in this context., Competing Interests: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research ® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2024 by the Association of Bone and Joint Surgeons.)

Background: Evolution of the surgical approach for total hip arthroplasty (THA) has led to the development of the minimally invasive direct superior approach (DSA). It is hypothesized that the DSA reduces postoperative pain and hospital length of stay (LOS). We aimed to provide an overview of current evidence on clinical, functional, and radiological outcomes with respect to risk of revision, complications, pain scores, physical function, operative time, LOS, blood loss, radiological outcomes, and learning curve., Methods: A comprehensive search of Medline, Embase, Web of Science, Cochrane Central Register of Controlled Trials, and Google Scholar, reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses literature search extension guidelines, was conducted to identify studies evaluating clinical, functional, and radiological outcomes of the DSA. Quality assessment was performed using the Cochrane Risk of Bias tool and Newcastle-Ottawa Scale. The review protocol was prospectively registered in the International Prospective Registry of Systematic Reviews., Results: Seventeen studies were included, generally of moderate quality. Qualitative synthesis evidenced accurate implant positioning, short LOS, and a short learning curve. Conflicting findings were reported for postoperative complications compared with conventional approaches. Better functional outcomes were seen in the early postoperative period than the posterolateral approach (PLA). Outcomes such as blood loss and operative time exhibited conflicting results and considerable heterogeneity., Conclusion: Based on moderate-certainty evidence, it is uncertain if the DSA provides short-term advantages over conventional approaches such as PLA. There is limited evidence on long-term outcomes post-THA using the DSA. Further studies and ongoing registry monitoring is crucial for continuous evaluation of its long-term outcomes., Level of Evidence: Level III. See Instructions for Authors for a complete description of levels of evidence., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSREV/B78)., (Copyright © 2024 The Authors. Published by The Journal of Bone and Joint Surgery, Incorporated. All rights reserved.)

Background and Purpose: Periprosthetic femoral fracture (PPF) after total hip arthroplasty (THA) is a serious complication, as it often is followed by functional deficits and morbidity. There is no consensus regarding the optimal stem fixation method and whether additional cup replacement is beneficial. The aim of our study was to perform a direct comparison of reasons and risk of re-revision between cemented and uncemented revision THAs following PPF using registry data., Patients and Methods: 1,879 patients registered in the Dutch Arthroplasty Registry (LROI) who underwent a first-time revision for PPF between 2007 and 2021 (cemented stem: n = 555; uncemented stem: n = 1,324) were included. Competing risk survival analysis and multivariable Cox proportional hazard analyses were performed., Results: 5- and 10-year crude cumulative incidence of re-revision following revision for PPF was similar between cemented (resp. 13%, 95% CI 10-16 and 18%, CI 13-24) and uncemented (resp. 11%, CI 10-13 and 13%, CI 11-16) revisions. Multivariable Cox regression analysis, adjusting for potential confounders, showed a similar risk of revision for uncemented and cemented revision stems. Finally, we found no difference in risk of re-revision between a total revision (HR 1.2, 0.6-2.1) compared with a stem revision., Conclusion: We found no difference in the risk of re-revision between cemented and uncemented revision stems after revision for PPF.

Background and purpose - Custom triflange acetabular components (CTACs) are suggested as good solutions for large acetabular defects in revision total hip arthroplasty. However, high complication rates have been reported and most studies are of limited quality. This prospective study evaluates the performance of a CTAC in patients with large acetabular defects including pelvic discontinuity.Patients and methods - Prospectively collected data of 49 consecutive patients (50 hips), who underwent an acetabular revision with a CTAC were analyzed. Follow-up (FU) was 2 years. The median age of the patients was 68 years (41-89) and 41 were women. Primary outcomes were re-revision of the CTAC and differences between the modified Oxford Hip Score (mOHS) preoperatively and at 2-year follow-up. Secondary outcomes included several patient-reported outcomes (PROMs), radiological results, complications, and a comparison between hips with and without pelvic discontinuity (PD).Results - 1 patient (1 hip) was lost to the 2-year FU. No CTAC needed re-revision. The preoperative and 2-year FU mOHS were available in 40 hips and improved statistically significantly. All of the other secondary outcomes improved over time. 5 hips (of 45 with radiological 2-year FU) had loosening of screws. 8 hips had complications, including 3 persistent wound leakage, 3 pelvic fractures, and 1 dislocation. The mOHS and complication rate were similar in hips with and without PD.Interpretation - Reconstruction of large acetabular defects with and without PD with this CTAC showed good improvement in patient-reported daily functioning, high patient-reported satisfaction, few complications, and no re-revisions at 2-year FU.

Aims: It is essential to exclude a periprosthetic joint infection (PJI) prior to revision surgery. It is recommended to routinely aspirate the joint before surgery. However, this may not be necessary in a subgroup of patients. The aim of our study was to investigate if specific clinical and implant characteristics could be identified to rule out a PJI prior to revision surgery., Methods: We retrospectively evaluated clinical and implant characteristics of patients who underwent a hip or knee revision surgery between October 2015 and October 2018. Patients were diagnosed with a PJI according to the MSIS diagnostic criteria., Results: A total of 156 patients were analyzed, including 107 implants that were revised because of prosthetic loosening and 49 because of mechanical failure (i.e. instability, malalignment or malpositioning). No PJI was diagnosed in the group with mechanical failure. In the prosthetic loosening group, 20 of 107 were diagnosed with a PJI (19%). Although there was a significantly lower chance of having a PJI with an implant age of > 5 years combined with a CRP < 5 mg/L, an infection was still present in 3 out of 39 cases (8%)., Conclusion: Implants with solely mechanical failure without signs of loosening and low inflammatory parameters probably do not require a synovial fluid aspiration. These results need to be confirmed in a larger cohort of patients. In case of prosthetic loosening, all joints need to be aspirated before surgery as no specific characteristic could be identified to rule out an infection.

Background: In acute periprosthetic joint infections (PJIs), a second surgical debridement (debridement, antibiotics, and implant retention [DAIR]) is generally not recommended after a failed first one. We identified the failure rate of a second DAIR and aimed to identify patients in whom an additional debridement might still be beneficial., Methods: Patients with acute PJI of the hip or knee and treated with DAIR between 2006 and 2016 were retrospectively evaluated. A second DAIR was routinely performed provided that the soft tissue was intact. Failure of a second DAIR was described as (1) the need for additional surgical intervention to achieve infection control, (2) the need for antibiotic suppressive therapy due to persistent clinical and/or biochemical signs of infection, or (3) PJI related death., Results: From the 455 cases treated with DAIR, 144 cases underwent a second debridement (34.6%). Thirty-seven cases failed (37/144, 25.7%). The implant needed to be removed in 23 cases (23/144, 16%). Positive cultures during the second DAIR (odds ratio 3.16, 95% confidence interval 1.29-7.74) and chronic renal insufficiency (odds ratio 13.6, 95% confidence interval 2.03-91.33) were independent predictors for failure in the multivariate analysis. No difference in failure was observed between persistent infection with the same microorganism and reinfection with a new microorganism (failure rate 31.6% vs 34.6%, P = .83)., Conclusion: A second DAIR had a low failure rate in our cohort of patients and the implant could be retained in the majority of them. Therefore, a second DAIR should not be discarded in acute PJIs., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Obese patients are more likely to develop periprosthetic joint infection (PJI) after primary total joint arthroplasty. This study compared the clinical and microbiological characteristics of non-obese, obese and severely obese patients with early PJI, in order to ultimately optimize antibiotic prophylaxis and other prevention measures for this specific patient category., Methods: We retrospectively evaluated patients with early PJI of the hip and knee treated with debridement, antibiotics and implant retention (DAIR) between 2006 and 2016 in three Dutch hospitals. Only patients with primary arthroplasties indicated for osteoarthritis were included. Early PJI was defined as an infection that developed within 90 days after index surgery. Obesity was defined as a BMI ≥30kg/m2 and severe obesity as a BMI ≥35kg/m2., Results: A total of 237 patients were analyzed, including 64 obese patients (27.0%) and 62 severely obese patients (26.2%). Compared with non-obese patients, obese patients had higher rates of polymicrobial infections (60.3% vs 33.3%, p<0.001) with more often involvement of Enterococcus species (27.0% vs 11.7%, p = 0.003). Moreover, severely obese patients had more Gram-negative infections, especially with Proteus species (12.9% vs 2.3%, p = 0.001). These results were only found in periprosthetic hip infections, comprising Gram-negative PJIs in 34.2% of severely obese patients compared with 24.7% in obese patients and 12.7% in non-obese patients (p = 0.018)., Conclusions: Our results demonstrate that obese patients with early periprosthetic hip infections have higher rates of polymicrobial infections with enterococci and Gram-negative rods, which stresses the importance of improving preventive strategies in this specific patient category, by adjusting antibiotic prophylaxis regimens, improving disinfection strategies and optimizing postoperative wound care., Competing Interests: The authors have declared that no competing interests exist.

Background and purpose - 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET) can be used in the diagnostic work-up of a patient with suspected periprosthetic joint infection (PJI) but, due to a lack of accurate interpretation criteria, this technique is not routinely applied. Since the physiological uptake pattern of FDG around a joint prosthesis is not fully elucidated, we determined the physiological FDG uptake in non-infected total hip prostheses. Patients and methods - Patients treated with primary total hip arthroplasty (1995-2016) who underwent a FDG-PET/CT for an indication other than a suspected PJI were retrospectively evaluated. Scans were both visually and quantitatively analyzed. Semi-quantitative analysis was performed by calculating maximum and peak standardized uptake values (SUV max and SUV peak ) by volume of interests (VOIs) at 8 different locations around the prosthesis. Results - 58 scans from 30 patients were analyzed. In most hips, a diffuse heterogeneous uptake pattern around the prosthesis was observed (in 32/38 of the cemented prostheses, and in 16/20 of the uncemented prostheses) and most uptake was located around the neck of the prosthesis. The median SUV max in the cemented group was 2.66 (95% CI 2.51-3.10) and in the uncemented group 2.87 (CI 2.65-4.63) (Median difference = -0.36 [CI -1.2 to 0.34]). In uncemented prostheses, there was a positive correlation in time between the age of the prosthesis and the FDG uptake (r s = 0.63 [CI 0.26-0.84]). Interpretation - Our study provides key data to develop accurate interpretation criteria to differentiate between physiological uptake and infection in patients with a prosthetic joint.

Background: Diagnosing a chronic prosthetic joint infection (PJI) can be challenging. We hypothesized that obtaining preoperative tissue samples for culture in hip arthroplasty will increase the likelihood of diagnosing an infection before revision surgery. The aim of this cohort study was to determine the diagnostic accuracy of 2 tissue acquiring biopsy strategies to diagnose a PJI., Methods: Patients with a painful hip arthroplasty, in which a chronic PJI was suspected, were included. Tissue samples were obtained either by ultrasound guidance with a 16-Gauge needle (2012-2013) or in the operating room with a thick-bore needle (2013-2016). Revision surgery tissue biopsies were used as the gold standard. Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio were calculated., Results: A total of 16 patients in the ultrasound cohort and 29 patients in the surgical cohort were included. Thirty-one percent (n = 14) were finally diagnosed with a PJI. The addition of thick bore needle tissue biopsies resulted in 9% more diagnosed PJIs compared with synovial fluid alone. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio was 33%, 85%, 33%, 85%, 2.2, and 0.8, respectively, for the ultrasound-guided biopsy cohort and 82%, 100%, 100%, 90%, infinite, and 0.2, respectively, for the surgical biopsy cohort., Conclusion: Obtaining multiple good quality tissue biopsies in a sterile environment will contribute to the diagnosis of a chronic PJI of the hip, with a higher diagnostic accuracy compared with ultrasound-guided thin needle biopsies and compared with synovial fluid culture alone., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Introduction: Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are highly successful treatment modalities for advanced osteoarthritis. However, prolonged wound leakage after arthroplasty is linked to prosthetic joint infection (PJI), which is a potentially devastating complication. On the one hand, wound leakage is reported as a risk factor for PJI with a leaking wound acting as a porte d'entrée for micro-organisms. On the other hand, prolonged wound leakage can be a symptom of PJI. Literature addressing prolonged wound leakage is scarce, contradictory and of poor methodological quality. Hence, treatment of prolonged wound leakage varies considerably with both non-surgical and surgical treatment modalities. There is a definite need for evidence concerning the best way to treat prolonged wound leakage after joint arthroplasty., Methods and Analysis: A prospective nationwide randomised controlled trial will be conducted in 35 hospitals in the Netherlands. The goal is to include 388 patients with persistent wound leakage 9-10 days after THA or TKA. These patients will be randomly allocated to non-surgical treatment (pressure bandages, (bed) rest and wound care) or surgical treatment (debridement, antibiotics and implant retention (DAIR)). DAIR will also be performed on all non-surgically treated patients with persistent wound leakage at day 16-17 after index surgery, regardless of amount of wound leakage, other clinical parameters or C reactive protein. Clinical data are entered into a web-based database. Patients are asked to fill in questionnaires about disease-specific outcomes, quality of life and cost effectiveness at 3, 6 and 12 months after surgery. Primary outcome is the number of revision surgeries due to infection within a year of arthroplasty., Ethics and Dissemination: The Review Board of each participating hospital has approved the local feasibility. The results will be published in peer-reviewed scientific journals., Trial Registration Number: NTR5960;Pre-results., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Background: Reconstruction of periacetabular defects after pelvic tumor resection ranks among the most challenging procedures in orthopaedic oncology, and reconstructive techniques are generally associated with dissatisfying mechanical and nonmechanical complication rates. In an attempt to reduce the risk of dislocation, aseptic loosening, and infection, we introduced the LUMiC ® prosthesis (implantcast, Buxtehude, Germany) in 2008. The LUMiC ® prosthesis is a modular device, built of a separate stem (hydroxyapatite-coated uncemented or cemented) and acetabular cup. The stem and cup are available in different sizes (the latter of which is also available with silver coating for infection prevention) and are equipped with sawteeth at the junction to allow for rotational adjustment of cup position after implantation of the stem. Whether this implant indeed is durable at short-term followup has not been evaluated., Questions/purposes: (1) What proportion of patients experience mechanical complications and what are the associated risk factors of periacetabular reconstruction with the LUMiC ® after pelvic tumor resection? (2) What proportion of patients experience nonmechanical complications and what are the associated risk factors of periacetabular reconstruction with the LUMiC ® after pelvic tumor resection? (3) What is the cumulative incidence of implant failure at 2 and 5 years and what are the mechanisms of reconstruction failure? (4) What is the functional outcome as assessed by Musculoskeletal Tumor Society (MSTS) score at final followup?, Methods: We performed a retrospective chart review of every patient in whom a LUMiC ® prosthesis was used to reconstruct a periacetabular defect after internal hemipelvectomy for a pelvic tumor from July 2008 to June 2014 in eight centers of orthopaedic oncology with a minimum followup of 24 months. Forty-seven patients (26 men [55%]) with a mean age of 50 years (range, 12-78 years) were included. At review, 32 patients (68%) were alive. The reverse Kaplan-Meier method was used to calculate median followup, which was equal to 3.9 years (95% confidence interval [CI], 3.4-4.3). During the period under study, our general indications for using this implant were reconstruction of periacetabular defects after pelvic tumor resections in which the medial ilium adjacent to the sacroiliac joint was preserved; alternative treatments included hip transposition and saddle or custom-made prostheses in some of the contributing centers; these were generally used when the medial ilium was involved in the tumorous process or if the LUMiC ® was not yet available in the specific country at that time. Conventional chondrosarcoma was the predominant diagnosis (n = 22 [47%]); five patients (11%) had osseous metastases of a distant carcinoma and three (6%) had multiple myeloma. Uncemented fixation (n = 43 [91%]) was preferred. Dual-mobility cups (n = 24 [51%]) were mainly used in case of a higher presumed risk of dislocation in the early period of our study; later, dual-mobility cups became the standard for the majority of the reconstructions. Silver-coated acetabular cups were used in 29 reconstructions (62%); because only the largest cup size was available with silver coating, its use depended on the cup size that was chosen. We used a competing risk model to estimate the cumulative incidence of implant failure., Results: Six patients (13%) had a single dislocation; four (9%) had recurrent dislocations. The risk of dislocation was lower in reconstructions with a dual-mobility cup (one of 24 [4%]) than in those without (nine of 23 [39%]) (hazard ratio, 0.11; 95% CI, 0.01-0.89; p = 0.038). Three patients (6%; one with a preceding structural allograft reconstruction, one with poor initial fixation as a result of an intraoperative fracture, and one with a cemented stem) had loosening and underwent revision. Infections occurred in 13 reconstructions (28%). Median duration of surgery was 6.5 hours (range, 4.0-13.6 hours) for patients with an infection and 5.3 hours (range, 2.8-9.9 hours) for those without (p = 0.060); blood loss was 2.3 L (range, 0.8-8.2 L) for patients with an infection and 1.5 L (range, 0.4-3.8 L) for those without (p = 0.039). The cumulative incidences of implant failure at 2 and 5 years were 2.1% (95% CI, 0-6.3) and 17.3% (95% CI, 0.7-33.9) for mechanical reasons and 6.4% (95% CI, 0-13.4) and 9.2% (95% CI, 0.5-17.9) for infection, respectively. Reasons for reconstruction failure were instability (n = 1 [2%]), loosening (n = 3 [6%]), and infection (n = 4 [9%]). Mean MSTS functional outcome score at followup was 70% (range, 33%-93%)., Conclusions: At short-term followup, the LUMiC ® prosthesis demonstrated a low frequency of mechanical complications and failure when used to reconstruct the acetabulum in patients who underwent major pelvic tumor resections, and we believe this is a useful reconstruction for periacetabular resections for tumor or failed prior reconstructions. Still, infection and dislocation are relatively common after these complex reconstructions. Dual-mobility articulation in our experience is associated with a lower risk of dislocation. Future, larger studies will need to further control for factors such as dual-mobility articulation and silver coating. We will continue to follow our patients over the longer term to ascertain the role of this implant in this setting., Level of Evidence: Level IV, therapeutic study.

We present a rare case of an immunocompetent host who developed a Candida albicans-infected total hip prosthesis. The infection could not be eradicated with debridement and extensive antifungal therapy. Our patient first underwent a resection of the proximal femur and local treatment with gentamicin-loaded cement beads. In a second procedure, a handmade cement spacer impregnated with voriconazole, amphotericin B, and vancomycin was placed. After 3 months of additional systemic antibiotic therapy, the patient remained afebrile, and a tumor prosthesis was placed. Six years postoperatively, she is doing well, walking with a small limp and no signs of recurrent infection. This is the first report on elution of voriconazole and amphotericin B from bone cement delivered at clinically significant concentrations for at least 72 hours., (Copyright © 2013 Elsevier Inc. All rights reserved.)