Convertible-platform shoulder arthroplasty.

Background: Shoulder arthroplasty has become an increasingly common procedure used to treat degenerative, inflammatory, and traumatic conditions of the glenohumeral joint. With a significant increase in primary anatomic and reverse total shoulder arthroplasty, revision procedures have likewise increased. Updates in shoulder arthroplasty have allowed for the convertibility of implants, which allows for the retention of both glenoid and humeral components during revision surgery. This review aims to highlight the epidemiology, indications, and outcomes of convertible-platform total shoulder arthroplasty procedures. Methods: A review of the current literature surrounding convertible-platform shoulder arthroplasty was completed to highlight the advantages and disadvantages of commercially available instrumentation and implant systems as well as their outcomes. Discussion: Leading causes of shoulder arthroplasty revision surgery include glenoid failure, implant instability, and rotator cuff dysfunction. Variations in implant design between inlay and onlay humeral components and metal-backed glenoid components are important considerations at the time of revision surgery. Advantages of convertible-platform systems include increased efficiency and decreased complications during revision procedures as well as shorter recovery, lower cost, and better functional outcomes. Limitations of convertible systems include poorly positioned components during the index procedure, excessive soft-tissue tensioning, and problems associated with metal-backed glenoid implants. Changes in arm length have also been documented. These findings indicate the benefit of additional research and design to improve the effectiveness and utility of convertible-platform shoulder arthroplasty systems.

Radiological Landmarks for Joint Line Level in Challenging Total Ankle Arthroplasty.

Background: Although Total Ankle Arthroplasty (TAA) is primarily performed for post-traumatic ankle arthritis with joint disruption, anatomical landmarks for Joint Line (JL) level are typically preserved. However, severe Post-Traumatic Bone Loss (PTBL) or TAA revision may render some landmarks unidentifiable, challenging JL restoration. Methods: Patients undergoing customized TAA for severe PTBL or revision were enrolled. Custom-made implants, based on 3D CT scans, were designed to address bone defects and provide adequate bone support. Evaluated parameters, measured on bilateral ankle weight-bearing radiographs taken preoperatively and 6-8 months postoperatively, included JL Height Ratio (JLHR) and the distances from JL to the Lateral Malleolus apex (LM-JL), the posterior colliculus of the Medial Malleolus (MM-JL), and the Gissane Calcaneal Sulcus (CS-JL). Reproducibility and variability were assessed, and comparisons were made between radiological parameters measured at TAA and those at the contralateral ankle. Results: Thirteen patients were included. Intra- and interobserver reliability demonstrated excellent values. The least variability was observed in the LM-JL distance. Statistically significant correlations were found between CS-JL and MM-JL distances in the operated limb and between the CS-JL of the operated limb and the contralateral ankle. While TAA parameters did not show statistically significant differences compared with the contralateral ankle, a trend toward proximalization of the JL was noted. Conclusions: This study demonstrated good reproducibility of the analyzed parameters for evaluating JL in TAA among patients with severe PTBL or undergoing revision surgery. However, these parameters cannot be deemed fully reliable. Given their potential weaknesses, it is crucial to identify more reproducible values, preferably ratios.

High Demand for Psychological Support in Patients Who Have Periprosthetic Hip and Knee Joint Infections: An Analysis of 13,976 Patients.

BACKGROUND: There is only sparse knowledge on the psychological burden of patients who have periprosthetic joint infections. The aim of our study was to assess the need for psychological support following total joint arthroplasty of the hip and knee. A special focus was set on patients who had aseptic and septic complications. METHODS: A total of 13,976 patients who underwent total hip (n = 6,926) or total knee arthroplasty (n = 7,050) between January 1, 2012 and December 31, 2019 at a single institution were retrospectively evaluated for the postoperative need for a psychological consultation. Data were collected on age, sex, type of surgery, and indications for revision procedures. The need for a psychological consultation was assessed during the daily postoperative visits, which were further coordinated by 2 institutional psychologists. RESULTS: The average age was 68 years (range, 12 to 100), and there were 63.5% women. The overall rate of psychological consultations was 1.7%. Patients who had a septic indication for revision surgery had an 18.7-fold higher rate of postoperative psychological consultations compared to patients following primary surgery and a 5.4-fold higher rate compared to patients who had an aseptic indication. In detail, this rate was 1.0% in the primary subgroup, compared to 7.7% following revision arthroplasty (P < .001). In the revision subgroup, the rate was 17.9% for septic and 3.3% for aseptic revision arthroplasty cases (P < .001). Postoperative psychological consultations were twice as frequent in women (2.1%) compared to men (1.0%), P < .001. CONCLUSIONS: The present study raises awareness of the markedly high psychological burden in revision arthroplasty cases, in the view of the high estimated number of unknown cases. There is a significant correlation between periprosthetic joint infectionsand the postoperative need for a psychological consultation, with women being at an even higher risk. Health care providers should aim at offering psychological support for patients who have a septic complication, with affected patients being at risk for psychological stress. LEVEL OF EVIDENCE: IV.

Five-Year Results of the Salto XT Revision Ankle Arthroplasty.

BACKGROUND: The treatment of failed ankle replacements is debated, and little is published about the medium- and long-term results of revision implants. We wanted to examine prosthesis survival and physical function at least 5 years after insertion of the Salto XT revision prosthesis. METHODS: All consecutive patients operated with a Salto XT revision prosthesis underwent clinical and radiologic examinations preoperatively and after 3, 12, 24, and 60 months. Complications and reoperations are described, and changes in patient-reported outcome measures and clinical scores are reported. RESULTS: Thirty patients were operated with a Salto XT revision prosthesis between March 2014 and March 2017. Three of these were revised (1 to a fusion and 2 to a new prosthesis), and 3 patients were reoperated with screw removal. A concurrent subtalar fusion was performed on 13 patients, and there was 1 case of likely nonunion after these procedures, but no reoperations. The mean AOFAS score increased from 39.2 (95% CI 30.8-47.5) preoperatively to 75.1 (95% CI 67.3-82.9) after 5 years, and the mean improvement was 34.2 points (95% CI 23.8-44.6). Mean EQ-5D increased from 0.36 (95% CI 0.30-0.42) preoperatively to 0.74 (95% CI 0.64-0.85) after 5 years, an improvement of 0.34 (95% CI 0.19-0.49). Radiolucent lines were present in all but 3 patients. Five-year prosthesis survival was 93% (83.6-100). CONCLUSION: This is the first study to present medium-term results of this implant. We found good improvement in outcome scores and good implant survival, but also a high prevalence of radiolucent lines.

Knee fusion versus above knee amputation as two options to deal with knee periprosthetic joint infection.

BACKGROUND: Periprosthetic joint infection (PJI) poses a significant challenge in total knee arthroplasty (TKA), with recurrence rates as high as 14-28%, leading to substantial morbidity and treatment costs. When conventional treatments fail, knee fusion and above-the-knee amputation (AKA) emerge as alternative options. Existing literature offers conflicting views on the efficacy and impact of knee fusion versus AKA with varied outcomes and limitations. METHODS: This retrospective national study spanning 2010-2022 investigates Knee Fusion and AKA as options for addressing Knee PJI. Utilizing PearlDiver Patient Records Database, procedural, and reimbursement data on over 100 million individuals from all the US was evaluated. Readmission rates, costs, and complications of the mentioned procedures were assessed using ICD-9 and ICD-10 codes within a 90-day period and one-year post-operation. Statistical analyses, including chi-square tests and regression models, were conducted using integrated R software. RESULTS: The study reveals a substantial escalation (p < 0.0001) in the proportion of patients opting for AKA compared to arthrodesis. While age as a demographic factor showed no significant difference, arthrodesis patients exhibited lower comorbidity scores (3.6 ± 2.9 vs. 4.6 ± 3.4, p < 0.001). Arthrodesis correlated with higher 90-day thromboembolism rates (9.2% vs. 7.3%, p < 0.001), blood transfusion requirements (23.2% vs. 14.4%, p < 0.001), and acute renal failure incidence (p = 0.008) but demonstrated lower rates of urinary tract infections (p = 0.047) and cerebrovascular accidents (p < 0.001). At 1 year, arthrodesis was associated with higher infection rates (38.7% vs. 36.4%, p < 0.001). Arthrodesis patients had significant increased 90-day and 1-year readmission rates and hospitalization costs ($12,732 vs. $18,826, p < 0.001). CONCLUSIONS: We found higher rates of 1-year thromboembolism, infection, acute renal failure, and readmission in the arthrodesis group. AKA patients had more sepsis and cerebrovascular accidents. A patient-centered conversation is best for persistent infections and failed revision TKA. Considering the patient's quality of life, goals, and health status, this discussion should cover each procedure's risks and complications.

Use of Hinged Implants for Multi-Stage Revision Knee Arthroplasty for Severe Periprosthetic Joint Infection: Remission Rate and Outcomes After a Minimum Follow-Up of 5 Years.

BACKGROUND: In severe periprosthetic joint infection (PJI) after total knee arthroplasty (TKA), multi-stage procedures are indicated for ongoing signs of infection after implant removal during the spacer interval of an intended two-stage exchange. In these cases, several additional debridement and spacer exchange surgeries may be necessary. Herein, we analyzed the complications, remission rate, and functional outcome after multi-stage revision arthroplasty using hinged TKAs. METHODS: Patients (n = 79) treated with multi-stage revision arthroplasty after chronic PJI of the knee were included (2010 to 2018). During the prosthesis-free interval, a static spacer containing antibiotic-loaded bone cement was implanted. The mean number of surgeries, including implant removal and revision arthroplasty, was 3.8 (range, 3 to 8). The mean duration from implant removal to revision arthroplasty was 83 days (range, 49 to 318). Complications, remission, and mortality were analyzed after a minimum follow-up of 5 years. Outcomes were assessed based on the Knee Society Score (KSS) and the Western Ontario McMasters University Osteoarthritis Index (WOMAC). RESULTS: During follow-up, 24 (30.4%) patients underwent revision surgery, with a mean time to surgical revision of 99 weeks (range, 1 to 261). After follow-up, the infection-free remission rate and overall mortality were 87.3 and 11.4%, respectively. The mean KSS was 74.3 (range, 24 to 99); the KSS Function Score was 60.8 (range, 5 to 100); and the WOMAC, 30.2 (range, 5 to 83). CONCLUSION: In difficult-to-treat cases, multi-stage revision arthroplasty showed high remission rates and low mortality after a follow-up of 5 years. The overall revision rate was comparably high, accounting for early and late reinfections most of the time. In cases of implant survival, functional outcomes comparable to those of revision hinge TKA reported in the literature can be achieved. Therefore, multi-stage procedures with additional debridement steps should be performed in cases of ongoing infections in intended two-stage procedures.

Performing Revision Arthroplasty Increases Surgeon and Practice Volumes Through the Generation of Subsequent Cases: A Retrospective Study.

Background: Revision total knee (TKR) and hip (THR) arthroplasty surgeries are disincentivized due to unfavorable reimbursement rates, surgical times, and complication rates. Our study investigates secondary benefits of performing these surgeries by generating subsequent cases for surgeons and practices. Methods: Patients undergoing TKR and THR between April 1, 2011, and January 1, 2019, at our tertiary academic institution were analyzed. Patients were identified with Current Procedural Terminology codes for TKR and THR. We calculated a subsequent surgery rate on the same or different joint by the initial surgeon or another surgeon within the practice to determine the procedure yield after initial revision arthroplasty. Results: One thousand six hundred twenty-five patients met inclusion criteria. Six hundred forty-nine (39.9%) patients received at least one subsequent procedure on any joint by any orthopaedic surgeon in the practice. Four hundred five patients (24.9%) underwent another procedure on any joint by the same surgeon. Two hundred sixty patients (16.0%) underwent another procedure on the same joint by the same surgeon, with 109 cases (41.9%) being a planned second stage of a 2-stage revision for infection. Two hundred eighty-five patients (17.5%) underwent another procedure on a different joint by the same surgeon, with 122 of these patients (42.8%) undergoing at least one primary total hip or knee arthroplasty. Conclusions: TKRs and THRs can increase surgeon and practice volumes through the generation of future cases, which are primarily the second stage of a 2-stage revision or primary joint arthroplasties on other joints.

Management of a Traumatic Collapse of the First Carpometacarpal Joint After Trapeziectomy With Suture Suspensionplasty: A Case Report.

Arthritis of the first carpometacarpal (CMC) joint is a common pathology hand surgeons encounter. Treatment begins with conservative measures, but when they fail, surgery is a viable option for providing relief to patients. The most widely used surgical technique is CMC arthroplasty with ligament reconstruction and tendon interposition (LRTI). However, more novel techniques such as trapeziectomy with suspensionplasty are gaining popularity. When surgical measures fail, it is important to identify the mechanism of failure and proper treatment options. There are multiple options for revision surgery at the surgeon's disposal, with no consensus on a superior technique. This case illustrates a patient with painful subsidence secondary to a traumatic collapse of the first CMC joint eight months status post suspensionplasty with trapeziectomy. After conservative measures failed to provide relief, it was decided that a surgical revision was appropriate. The surgeon chose to move forward with suture button suspensionplasty, as it has multiple advantages over LRTI. In the short-term follow-up after revision, the patient experienced improvements in pain and range of motion, along with radiographic evidence of proper alignment of the first metacarpal without subsidence. Regarding the treatment of a case such as this, the authors believe this case should serve as a reference that may be used by future physicians when deciding which surgical technique to employ for the revision of a traumatically collapsed first CMC joint after trapeziectomy with CMC joint suspensionplasty.

Mouldable Collagen-Tricalciumphosphate Is a Safe Carrier for Local Antibiotics-Short-Term Results in Revision Hip Arthroplasty.

BACKGROUND: Improving local antibiotic delivery is a promising approach to improve infection control and potentially shorten systemic treatment in periprosthetic joint infection (PJI). This study investigates the use of an antibiotic-loaded, mouldable collagen-tricalciumphosphate composite in treatment of hip PJI. METHODS: 124 application cases in 79 patients were included from a referral centre; systemic adverse infects, local complications, and infection control were analysed. RESULTS: In most cases, either vancomycin or meropenem were used. Pathogens were previously known in 82 (66%) cases with polymicrobial infection in 20 (25%) patients. There were no cases of hypercalcaemia. Acute kidney injure was present in 14 (11%) cases. Chronic kidney failure persisted in two cases. During a mean follow-up of 12 (SD 9.3; range 3-35) months, implant survival was achieved in 73 (92%) patients; revision due to PJI was performed in 19 cases. CONCLUSION: Mouldable collagen-tricalciumphosphate composite bone substitute as a local antibiotic carrier in revision hip arthroplasty appears to be a valid option for local antibiotic delivery without systemic complications. Implant survival of 92% supports the hypothesis that local antibiotic therapy is an important component in the treatment of PJI.

Effect of Multiantibiotic-Loaded Bone Cement on the Treatment of Periprosthetic Joint Infections of Hip and Knee Arthroplasties-A Single-Center Retrospective Study.

BACKGROUND: Two-stage septic revision is the prevailing method for addressing late periprosthetic infections. Using at least dual-antibiotic-impregnated bone cement leads to synergistic effects with a more efficient elution of individual antibiotics. Recent data on the success rates of multiantibiotic cement spacers in two-stage revisions are rare. METHODS: We conducted a retrospective follow-up single-center study involving 250 patients with late periprosthetic hip infections and 95 patients with prosthetic knee infections who underwent septic two-stage prosthesis revision surgery between 2017 and 2021. In accordance with the antibiotic susceptibility profile of the microorganisms, a specific mixture of antibiotics within the cement spacer was used, complemented by systemic antibiotic treatment. All patients underwent preoperative assessments and subsequent evaluations at 3, 6, 9, 12, 18, and 24 months post operation and at the most recent follow-up. RESULTS: During the observation period, the survival rate after two-step septic revision was 90.7%. Although survival rates tended to be slightly lower for difficult-to-treat (DTT) microorganism, there was no difference between the pathogen groups (easy-to-treat (ETT) pathogens, methicillin-resistant staphylococci (MRS), and difficult-to-treat (DTT) pathogens). Furthermore, there were no differences between monomicrobial and polymicrobial infections. No difference in the survival rate was observed between patients with dual-antibiotic-loaded bone cement without an additional admixture (Copal® G+C and Copal® G+V) and patients with an additional admixture of antibiotics to proprietary cement. CONCLUSION: Employing multiple antibiotics within spacer cement, tailored to pathogen susceptibility, appears to provide reproducibly favorable success rates, even in instances of infections with DTT pathogens and polymicrobial infections.

Total Knee Arthroplasty Periprosthetic Joint Infection With Concomitant Extensor Mechanism Disruption and Soft-Tissue Defect: The Knee Arthroplasty Terrible Triad.

BACKGROUND: Periprosthetic infection (PJI) with concomitant extensor mechanism disruption (EMD) and soft-tissue defect-hereinafter termed the "Terrible Triad"-is a devastating complication following total knee arthroplasty. The purpose of this study was to define the surgical and clinical outcomes following management of a cohort of patients who have the Terrible Triad. METHODS: From 2000 to 2022, 127 patients underwent operative management for PJI alone, 25 for PJI with soft-tissue defects (defined as defects requiring flap reconstruction or being a factor contributing to the decision of performing above-knee amputation or arthrodesis), 14 for PJI with EMD, and 22 for the Terrible Triad. A composite outcome of infection status, range of motion, extensor lag, and ambulatory status at final follow-up was used to compare the proportion of patients in each group with a favorable overall knee outcome. Differences between groups were determined using one-way analyses of variance with post hoc Tukey's tests and Pearson's Chi-square tests or Fisher's exact tests with post hoc Bonferroni adjustments, where applicable. Odds ratios (OR) were calculated for comparison of the overall knee outcome between groups. A Kaplan-Meier survival analysis for patient mortality was performed. RESULTS: The mean follow-up was 8.4 years and similar between groups (P = .064). Patients who had the Terrible Triad had a 45.5% incidence of above-knee amputation, or arthrodesis, and an 86.4% incidence of an unfavorable outcome. Compared to patients in the PJI group, patients in the PJI who had a soft-tissue defect (OR = 5.8, 95% CI [confidence interval] 2.2 to 15.7), PJI with EMD (OR = 3.7, 95%CI 1.0 to 12.9), and Terrible Triad groups (OR = 11.6, 95% CI 3.3 to 41.5) showed higher odds of an unfavorable knee outcome. CONCLUSIONS: This study demonstrates that the total knee arthroplasty Terrible Triad is a dreaded diagnosis with poor outcomes. Clinicians and patients might consider early treatment with amputation or arthrodesis. LEVEL OF EVIDENCE: III.

10-Year Cumulative Incidence and Indications for Revision Total Joint Arthroplasty for Patients Who Have Ehlers-Danlos Syndrome.

BACKGROUND: Long-term complications following total joint arthroplasty are not well established for patients who have Ehlers-Danlos syndrome (EDS), a group of connective tissue disorders. This study compared 10-year incidence of revision surgery after total hip arthroplasty (THA) and total knee arthroplasty (TKA) in patients who have and do not have EDS. METHODS: A retrospective cohort analysis was conducted using a national all-payer claims database from 2010 to 2021 to identify patients who underwent primary TKA or THA. Patients who had and did not have EDS were propensity score-matched by age, sex, and a comorbidity index. Kaplan-Meier analyses and Cox proportional hazard models were used to determine the cumulative incidence and risks of revision experienced by patients who have and do not have EDS. RESULTS: The EDS patients who underwent TKA had a higher risk of all-cause revision (hazard ratio [HR]: 1.50, 95% confidence interval [95% CI]: 1.09 to 2.07, P < .014) and risk of revision due to instability (HR = 2.49, 95% CI: 1.37 to 4.52, P < .003). The EDS patients who underwent THA had a higher risk of all-cause revision (HR = 2.32, 95% CI: 1.47 to 3.65, P < .001), revision due to instability (HR = 4.26, 95% CI: 2.17 to 8.36, P < .001), and mechanical loosening (HR = 3.63, 95% CI: 2.05 to 6.44, P < .001). CONCLUSIONS: Patients who had EDS were found to have a higher incidence of revision within 10 years of undergoing TKA and THA compared to matched controls, especially for instability. Patients who have EDS should be counseled accordingly. Surgical technique and implant selection should include consideration for increased constraint in TKA and larger femoral heads or dual mobility articulations for THA.

Under-reporting by surgical pathologists in tissue removed during revision surgery for metal-on-metal arthroplasties.

Although adverse local tissue reactions (ALTR) have been reported for metal-on-metal implants (MoM) requiring early revision surgery, no study has looked at the accuracy of surgical pathologists in diagnosing ALTR. This study aims to investigate the accuracy of reporting adverse local tissue reactions in tissue samples following revision surgery from metal-on-metal implants. The authors reviewed histology glass slides as well as the original pathology reports of tissue processed in revision arthroplasties in 23 cases. These samples were microscopically analyzed for tissue necrosis and cystic degeneration, the presence of metal particles, corrosion byproducts, membrane formation, histiocytic cells, lymphocytic cells, and vascular pathology. The authors' findings were then compared to their corresponding original pathology reports. The authors found consistent under-reporting of the tissue findings. Most importantly, 18 samples showed evidence of metal present compared to 2 samples on original pathology reporting. The authors found that 15 samples showed evidence of pathological membranous tissue compared to just 6 on original pathology reporting. While just 3 of the original pathology reports indicated the presence of areas of predominantly lymphocytic inflammatory cells, the authors found 13 examples of such areas. Although ALTR reactions have been described as a sequala of failed MoM, the authors' data suggest that ALTR may occur more frequently than previously described. Under-reported findings of ALTR deprive both the patient and orthopaedic surgeon of important information that can help guide further follow-up.

Postoperative Vitamin D Surveillance and Supplementation in Revision Total Knee Arthroplasty Patients: A Retrospective Cohort Analysis.

This study was a retrospective cohort analysis of 20 patients who underwent 23 revision total knee arthroplasty procedures in a single geographic region of the United States from January 2015 to February 2023. We analyzed their 25-OH vitamin D levels preoperatively and postoperatively at 1 month, 3 months, 6 months, 1 year, and 2 years. We categorized their supplementation regimens by dose: none, low dose (1000 IU and below), medium dose (1001-5000 IU), and high dose (>5000 IU). We found that there was a high incidence of vitamin D deficiency in this patient population.

Use of an Artificial Intelligence Device for Evaluating Blood Loss in Complex Major Orthopaedic Surgery Procedures.

BACKGROUND: An artificial intelligence algorithm that analyzes the pulse oximeter waveform in the fingertip can be used to determine the compensatory reserve index (CRI) in trauma patients. This measurement shows the remaining cardiovascular capacity and is known to be more specific and sensitive in detecting blood loss than are routine vital signs. We hypothesized that the CRI measurement could predict loss of reserve cardiovascular capacity in patients undergoing major orthopaedic surgery, and therefore could help in their management. METHODS: A total of 304 patients undergoing lower extremity arthroplasty consented to participate in waveform monitoring. Pulse oximeter waveforms were sensed with a fingertip probe and processed with a tablet computer that remained with the patient during surgery and recovery in the hospital. The CRI, systolic blood pressure, and heart rate were evaluated throughout the postoperative period. RESULTS: The CRI measurement identified a group of patients who were significantly more likely to require transfusions and emergency medical care (P = .000021). Patients who had morbid obesity were especially likely to have low CRI results and a high percentage of clinical events. A CRI of 0.40 or more was evaluated retrospectively as the criterion for withholding transfusion in 54 patients, but that group had a significantly higher incidence of transfusion later in treatment than did the cohort as a whole. The systolic blood pressure and heart rate were not useful in predicting the need for transfusion until late in treatment. CONCLUSIONS: This study suggests that the CRI measurement can identify patients at risk for transfusion and the need for urgent medical care and may aid in the management of blood loss and transfusion in major orthopedic surgery.

Individualized megaimplants in acetabular revision arthroplasty: what have we learned in the last 15 years?

Acetabular revision arthroplasty, a demanding field of reconstructive hip surgery, calls for innovative strategies to deal with challenging bone defects and implant failure seen in revision cases. Conventional implant solutions might fall short of adequately addressing severe bone loss and ensuring stable fixation, highlighting the necessity of customized strategies. Personalized megaimplants, distinguished by their tailor-made design and large-scale construction, present a viable option to overcome these challenges. The present article provides an elaborate analysis of custom-made megaimplants in acetabular revision arthroplasty, shedding light on the underlying principles, design complexities, manufacturing methods, applications in the clinical setting, and outcome assessment. The aim of this review is to present a comprehensive insight into personalized megaimplants and their contribution to the advancement of orthopedic surgery.

Proximal femoral defect classifications in revision total hip arthroplasty from X-rays imaging to advanced 3D imaging: a narrative review.

Background and Objective: Femoral bone defect in hip arthroplasty revision surgery represents a complex problem, and the treatment is a challenge for orthopedic surgeons called to assess the residual bone stock in an altered anatomy and obtain stability for the new implant. Classification systems available are mostly based on X-rays two-dimensional images and lack of accuracy and reproducibility and comprehensive therapeutic algorithms. However, there is no record of any classification based on computed tomography (CT)-scan images or three-dimensional (3D) modeling modern techniques. We aimed to review the current literature around femoral defect classifications (FDCs) analyzing their different rationale basis, reliability and accuracy, and their benefit in clinical practice. Moreover, we highlighted the role of CT scan-based 3D modeling techniques in the setting of femoral bone defects and revision hip arthroplasty. Methods: A narrative review was conducted. The articles were selected from the PubMed and Scopus medical database updated to March 2023. All Level-I to IV studies in the English language were considered for inclusion. The research was performed using relevant search term items: "femoral defects", "classification", "radiographic", "revision hip arthroplasty", "CT scan" and "3D" and we included only articles that evaluated the accuracy or reliability (or both) of the different femoral bone defects classification system. Key Content and Findings: Our search yielded 408 results, of which 17 were deemed highly relevant. We found seven X-ray-based classification systems which have been attempted to quantify the degree of bone loss with low to good reproducibility. The most used classification system for femoral bone defects were the AAOS and Paprosky classification, which also offers a clinical therapeutic algorithm. In 2021, the FDC interestingly showed a new simple classification system with sub-optimal reproducibility and a practical therapeutic algorithm. Despite the numerous classification system of femoral defects, none of them comprehends the use of CT scan and 3D imaging technologies. Conclusions: Traditional X-rays-based classification system are still widely used event if their intra-observer and inter-observer reliability is sub-optimal. 3D modeling techniques represent an important diagnostic tool that could improve the understanding of bone defects and residual bone supportive structures, allowing to elaborate new, more precise, classification systems.

Prediction of 30-Day Mortality Following Revision Total Hip and Knee Arthroplasty: Machine Learning Algorithms Outperform CARDE-B, 5-Item, and 6-Item Modified Frailty Index Risk Scores.

BACKGROUND: Although risk calculators are used to prognosticate postoperative outcomes following revision total hip and knee arthroplasty (total joint arthroplasty [TJA]), machine learning (ML) based predictive tools have emerged as a promising alternative for improved risk stratification. This study aimed to compare the predictive ability of ML models for 30-day mortality following revision TJA to that of traditional risk-assessment indices such as the CARDE-B score (congestive heart failure, albumin (< 3.5 mg/dL), renal failure on dialysis, dependence for daily living, elderly (> 65 years of age), and body mass index (BMI) of < 25 kg/m2), 5-item modified frailty index (5MFI), and 6MFI. METHODS: Adult patients undergoing revision TJA between 2013 and 2020 were selected from the American College of Surgeons National Surgical Quality Improvement Program database and randomly split 80:20 to compose the training and validation cohorts. There were 3 ML models - extreme gradient boosting, random forest, and elastic-net penalized logistic regression (NEPLR) - that were developed and evaluated using discrimination, calibration metrics, and accuracy. The discrimination of CARDE-B, 5MFI, and 6MFI scores was assessed individually and compared to that of ML models. RESULTS: All models were equally accurate (Brier score = 0.005) and demonstrated outstanding discrimination with similar areas under the receiver operating characteristic curve (AUCs, extreme gradient boosting = 0.94, random forest = NEPLR = 0.93). The NEPLR was the best-calibrated model overall (slope = 0.54, intercept = -0.004). The CARDE-B had the highest discrimination among the scores (AUC = 0.89), followed by 6MFI (AUC = 0.80), and 5MFI (AUC = 0.68). Albumin < 3.5 mg/dL and BMI (< 30.15) were the most important predictors of 30-day mortality following revision TJA. CONCLUSIONS: The ML models outperform traditional risk-assessment indices in predicting postoperative 30-day mortality after revision TJA. Our findings highlight the utility of ML for risk stratification in a clinical setting. The identification of hypoalbuminemia and BMI as prognostic markers may allow patient-specific perioperative optimization strategies to improve outcomes following revision TJA.