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Introduction: Modern primary cementless total knee arthroplasty (TKA) is increasingly popular, but there is limited evidence on its benefits, early complications, and failures. Purpose: We sought to evaluate operative time, early survivorship, and outcomes of cementless versus cemented TKA of the same design. Methods: As part of this single-center, multisurgeon, retrospective cohort study, we reviewed 598 primary, unilateral TKAs (170 cementless, 428 cemented) of the same design from 2016 to 2018. The cementless cohort was younger (63 vs 67 years) and had more cruciate-retaining implants (17% vs 12%) compared with the cemented cohort. We compared operative time, length of stay, and complications. Survivorship curves were generated via the Kaplan-Meier method. Results: Patients with cementless TKA (using the Triathlon implant, Stryker) had a 24% reduction in operative time (83 vs 109 minutes) but similar length of stay compared with those with cemented TKA (57 vs 61 hours). Cementless TKA had a higher rate of postoperative manipulation for stiffness compared with cemented TKA (8% vs 3%), but there were notable demographic differences between the cohorts. Despite 2 cases (1%) of early cementless tibial aseptic loosening requiring component revision compared with none in the cemented cohort, there was no difference in revision-free survivorship at 2 years (96% and 98%, respectively). Conclusion: This retrospective cohort study found that cementless TKA had a 24% reduction in operative time compared with cemented TKA and similar short-term survivorship. There was a slightly higher rate of aseptic revision and manipulation in the cementless cohort. Further study is warranted on the long-term durability of cemented and cementless TKAs to determine if cementless fixation proves more durable in the midterm to long term.

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BACKGROUND: Treatment of patients with Crowe type III and IV dislocated hips is challenging because of the hip deformity in these patients. In addition to the usual total hip replacement, shortening and reduction of the femur are often required. We herein report on our surgical technique using a monoblock cylindrical cementless stem and a direct lateral approach. METHODS: This study included patients with a diagnosis of severe developmental dysplasia of the hip (Crowe types III and IV) who underwent primary total hip arthroplasty at our hospital from August 2019 to January 2022. Eleven hips of seven patients were treated. All patients underwent horizontal osteotomy using a monoblock cylindrical cementless stem and a direct lateral approach. Complications such as dislocation, infection, and implant dropout were evaluated. In addition, the clinical assessment included the hip range of motion at the last observation and hip function based on the Japanese Orthopaedic Association (JOA) hip score and the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ). RESULTS: The average operation time was 224 min (range, 194-296 min), and the average bleeding amount was 396.1 g (range, 20-1010 g). The main complications were acetabular implant dislocation, postoperative dislocation, intraoperative arterial injury, intraoperative proximal femoral fracture, subsidence of femoral implant. and postoperative pulmonary infarction, which occurred in one patient each. CONCLUSION: Total hip arthroplasty for Crowe type III and IV hips is associated with various surgical technical difficulties because of its anatomical characteristics. While patients with severe osteoporosis are contraindicated, the use of a cylindrical monoblock cementless stem and the direct lateral approach makes it possible to simplify the procedure for shortening the femur and increase the indications for surgery. LEVEL OF EVIDENCE: Therapeutic Level Ⅳ.

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BACKGROUND: The purpose of this study is to assess the short-term survivorship of a new cementless total knee arthroplasty (TKA) design in comparison to its cemented predecessor design in a young patient cohort less than 65 years of age. METHODS: We performed a retrospective cohort study of all primary TKAs (cemented and cementless) in patients under the age of 65 at the time of the index procedure, in a single institution between May 2018 and May 2019. Primary outcome variables included aseptic revision and all-cause revision. Operative time was a secondary variable. Independent variables considered included age, sex, body mass index (BMI), American Society of Anesthesiologists (ASA) grade, implant type (cruciate-retaining (CR) or posterior-stabilised (PS)) and the use of cemented or cementless implants. RESULTS: There were 106 cemented TKAs and 152 cementless TKAs (Triathlon, Stryker Inc, Mahwah, NJ ) implanted. The minimum follow-up for all cases was 2 years (mean cementless 32.5 months, mean cemented 34.9 months). Of the entire 258 implants only 2 were revised. Both revisions occurred in the cemented cohort for prosthetic joint infection (PJI). The all-cause revision rate in the cementless cohort was 0% compared to 1.8% in the cemented cohort (p = 0.168). Operative times were significantly reduced from 62 min in the cemented cohort to 52.2 min in the cementless cohort (p < 0.001). CONCLUSION: In a young patient cohort, the cementless Triathlon TKA demonstrates excellent survivorship at short-term follow-up with significant reductions in operative times when compared to the cemented Triathlon TKA.

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INTRODUCTION: Implementing new approaches or new implants is always related with a certain learning curve in total hip arthroplasty (THA). Currently, many surgeons are switching to minimally invasive approaches combined with short stems for performing THA. Therefore, we aimed to asses and compare the learning curve of switching from an anterolateral Watson Jones approach (ALA) to a direct anterior approach (DAA) with the learning curve of switching from a neck-resecting to a partially neck-sparing short stem in cementless THA. MATERIALS AND METHODS: The first 150 consecutive THA performed through a DAA (Group A) and the first 150 consecutive THA using a partially neck-sparing short stem (Group B) performed by a single surgeon were evaluated within this retrospective cohort study. All cases were screened for surgery related adverse events (AE). Furthermore, the operative time of each surgery was evaluated and the learning curve assessed performing a cumulative sum (CUSUM) analysis. RESULTS: Overall, significantly more AE occurred in Group A compared to Group B (18.0% vs. 10.0%; p = 0.046). The sub-analysis of the AE revealed higher rates of periprosthetic joint infections (2.7% vs. 0.7%; p = 0.176), periprosthetic fractures (4.0% vs. 2.0%; p = 0.310) and overall revisions (4.7% vs. 1.3% p = 0.091) within Group A without statistical significance. The CUSUM analysis revealed a consistent reduction of operative time after 97 cases in Group A and 79 cases in Group B. CONCLUSION: A significantly higher overall rate of AE was detected while switching approach compared to switching implant for performing THA. However, according to the results of this study, surgeons should be aware of the learning curve of the adoption to a new implant with different fixation philosophy as well.

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Background: Leg length discrepancy following hip arthroplasty causes dissatisfaction to the patient; thus, preoperative planning and implant selection is critical. The purpose of this study was to measure the articular-trochanteric distance (ATD) and femoral neck length (FNL) in our population and compare them to those of 3 of the most used uncemented stems. Methods: In this cross-sectional study, 401 hip radiographs of healthy adults were collected between January and July 2022. The vertical ATD and FNL were measured. A linear regression model was used to identify the relationship between these measurements and age, sex, and height. A logistic regression model was used to assess the matching of native hips with the neck length of the stem. Results: Mean age was 60 years, and 74.56% were women. In 94.3% of hips, the ATD was negative, 3.73% neutral, and 2% positive. In our population, 0.25% of FNL were shorter than POLARSTEM (Smith & Nephew, UK), 10.72% shorter than MetaFix stem (Corin, UK), and 11.97% shorter than Corail stem (DePuy Synthes, USA). In the logistic regression analysis, matching for the POLARSTEM was associated with age but not with sex or height. Conversely, for MetaFix and Corail, stem matching was associated with sex and height. Conclusions: Anthropometric hip measurements vary among individuals, and variables such as age, sex, and height must be considered during preoperative planning and implant selection to avoid leg length discrepancy. Additional studies, including different implants, are required to guide surgeons in selecting a femoral stem that best matches the patient's native hip.

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Removing well-fixed uncemented components can be challenging. With thoughtful surgical planning, appropriate surgical instruments, and proper surgical techniques, most implants can be removed expeditiously with little bone loss and minimal impact on the subsequent reconstruction. Preoperative planning is one of the most essential steps to remove uncemented implants. Obtaining previous surgical records, although tedious, should always be attempted preoperatively to determine if specific instruments will be required and to help anticipate which steps may need special attention. These include the presence of ceramic or metal bearings and the presence of acetabular screws or stem collars. Without proper preparation and available tools, the removal of implants can negatively impact the subsequent reconstruction and patient outcomes. We will describe techniques and practical tips for removing uncemented stems from the top (intramedullary) or transfemoral using an extended trochanteric osteotomy. We will also describe techniques and tools to remove uncemented acetabular shells efficiently. Case examples will highlight these clinical situations where careful planning is necessary and potential problems that may be encountered with the recurring theme of preparing for the worst but hoping for the best. We have also included cases such as removing well-fixed cementless collared stems, broken stems, and fully coated stems.

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BACKGROUND: In total knee arthroplasty (TKA), cementless fixation is initially weaker than cement fixation. This study aimed to examine whether filling the tibial peg holes with bone improves initial fixation strength in cementless TKA. METHODS: This prospective, comparative study examined 88 joints in 66 patients randomized to the bone filling (48 joints) or conventional group (no bone filling; 40 joints). All patients underwent TKA with the NexGen® trabecular metal modular tibial component. In the bone filling group, resected cancellous bone was filled into the peg holes before insertion of the tibial component. We performed clinical and plain radiographic evaluations after the operation and measured bone mineral density (BMD) at five sites below the component at 1, 3, 6, and 12 months postoperatively. RESULTS: Operative time and clinical evaluations were not significantly different. Plain radiography showed significant longitudinal thickening of the trabecula below the peg (P<0.05) and decreased occurrence of reactive lines (P=0.07) in the bone filling group compared with the conventional group. BMD was significantly higher in the bone filling group in the medial region below the peg at 1, 3, and 6 months and in the central region at 1 and 3 months (all P<0.05). CONCLUSIONS: When using the NexGen trabecular metal modular tibial component, concurrent peg hole bone filling increases the initial component fixation strength. Possible effects on long-term stabilization warrant further study.

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OBJECTIVE: Previous cementless total knee arthroplasty (TKA) designs faced challenges with insufficient initial fixation on tibial side, resulting in inferior functional outcomes and survival rates. The Zoned Trabecular Bone Cementless Knee is a novel implant designed for cementless TKA which aims to achieve excellent initial fixation, promoting effective osseointegration. The aim of this research was to compare the early clinical and radiographic results of this cementless TKA with cemented TKA. METHODS: Between September 2021 and April 2022, 64 patients (64 knees) were recruited in this prospective randomized controlled trial to receive either cementless 3D-printed trabecular metal TKA or a cemented posterior stabilized TKA. Preoperative and postoperative clinical evaluations, including the range of motion (ROM), Knee Society Score (KSS), and the Reduced Western Ontario and MacMaster Universities Score (WOMAC), were conducted and analyzed for comparison. Radiographs and computed tomography scans were utilized to assess the initial fixation. The complications between the two groups were also recorded and compared. Continuous data were analyzed for significance using independent-samples t-test or the Mann-Whitney U test and categorical data were analyzed using chi-squared or Fisher's exact test. RESULTS: Both groups demonstrated significant enhancement at 12 months follow-up in the ROM compared with baseline (ROM: 94.7 ± 23.4 vs. 113.1 ± 12.3 in cementless group and 96.5 ± 14.7 vs. 111.0 ± 12.8 in cemented group, p < 0.05). However, no statistical differences were observed between the two groups in postoperative ROM, KSS, or WOMAC score. The radiographs and computed tomography scans showed similar results, including radiolucent lines and osteolysis in either femoral or tibial. Additionally, there was no statistical difference in the overall complication rate between the two groups. Notably, one patient in the cementless TKA group required revision for periprosthetic infection as the end point. CONCLUSIONS: This novel 3D-printed trabecular metal cementless TKA achieved comparable clinical outcomes and initial fixation to cemented TKA in early stage. Longer-term examination is necessary to validate these results.

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Total knee arthroplasty is a consistently successful, cost-efficient, and highly effective surgical procedure for treating severe knee osteoarthritis. The success and longevity of total knee arthroplasty depend significantly on the fixation method used to secure the prosthetic components. This comprehensive review examines the primary fixation methods (cemented, cementless, and hybrid fixation), analysing their biomechanics, clinical outcomes, advantages, and disadvantages, focusing on recent advances and trends in total knee arthroplasty fixation.

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Intraoperative acetabular fractures (IAFs), a complication seldomly encountered in total hip arthroplasty, are typically a result of the impact of insertion of a cementless press-fit cup. Factors that contribute to the risk of these types of fractures include poor bone quality, highly sclerotic bone, and the use of a press-fit cup that is excessively large. The approach to management of these fractures is dependent on when they are identified. Immediate stabilization measures should be implemented for management of fractures detected during surgery. When fractures are detected postoperatively, the decision regarding conservative treatment is dependent on the stability of the implant and the specific fracture pattern. In the majority of cases, effective treatment of an acetabular fracture detected intraoperatively can be administered using a multi-hole revision cup along with anchoring screws in the various regions of the acetabulum. Selection of plate osteosynthesis of the posterior column is recommended when there is a large posterior wall fragment or pelvic discontinuity. In cases where anatomical dimensions allow, cup-cage reconstruction may offer a promising alternative to a combined hip procedure. The number of reports addressing the management of IAFs is limited. This review focuses on outlining the strategies that are currently available for management of this seldomly encountered complication.

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BACKGROUND: Cementless total knee arthroplasty (TKA) is rising in popularity. The literature supporting its use over cemented TKA remains sparse. Using the Canadian Joint Replacement Registry (CJRR), we sought to investigate cementless versus cemented fixation in modern primary TKA and (1) determine whether there is an overall difference in revision by fixation, (2) perform a subanalysis of the most-commonly used cementless TKA brand in Canada, and (3) identify the reasons for revision. METHODS: The CJRR data was used to analyze TKA designs with cemented and cementless versions. Revision risk is reported as all-cause cumulative percent revision (CPR). Reasons for revision were analyzed. Cox proportional hazards models were used to report adjusted hazard ratios (HR) controlling for age, sex, patella resurfacing, and bearing constraints. We included 202,880 primary TKAs performed between 2012 and 2021. Of those, 9,163 (4.5%) were cementless. RESULTS: The CPR at 8 years was 4.49% for cementless and 3.14% for cemented implants. After adjusting for confounders, we did not detect a difference in revision risk overall (HR 0.87 [95% CI (confidence interval) 0.73 to 1.04], P = 0.128). However, the most commonly used cementless TKA brand demonstrated a CPR of 1.95% compared to 2.19% for its cemented version at 4 years. Furthermore, we detected a significantly lower revision risk compared to its cemented version after adjusting for confounders (HR 0.66 [95% CI 0.51 to 0.85], P = 0.001). The 4 most common reasons for revision in both groups were the following: (1) infection, (2) instability, (3) aseptic loosening, and (4) pain of unknown origin. CONCLUSIONS: Using CJRR data adjusted for confounding factors, no difference in revision risk was detected between cemented and cementless implants overall. However, for the most common brand of cementless TKA used in Canada, there was a lower risk of revision than its corresponding cemented version. The reasons for revision were similar.

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In patients with severe hip dysplasia, total hip arthroplasty (THA) using bulk bone graft (BBG) enhances anatomic cup positioning and provides early structural support. This study assesses the mid-term outcomes of THA with BBG in patients with over 50% graft bone coverage. Among 1951 patients who underwent THA between 2003 and 2007, 183 had BBG. After excluding early dropouts and infections, 151 patients remained. They were classified into uncovered (<50% coverage, 79 patients) and covered (>50% coverage, 72 patients) groups. The efficacy of cup fixation was compared between these groups. After ten years, the survival rate for not needing THA revision was 98% in the uncovered group and 100% in the covered group, while the rate for radiographic stability was 93% versus 99%, respectively. Although the cutoff value for the uncovered portion could not be clarified in this study, the mid-term results for 50% to approximately 70% uncovered were comparable to those for 50% or lesser, which have previously been expected to perform well. Recently, biomechanically advantageous bone grafting techniques have been identified, and based on the results of this study, it may be possible to expand the indications for THA with bone grafting for developmental dysplasia of the hip.

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BACKGROUND: In recent years, the indication for cementless short stem total hip arthroplasty (THA) has been widened to elderly patients as they might profit by the advantages of the short-curved implant design as well. Therefore, this study was conducted to evaluate the clinical and radiological outcome of a cementless short stem in elderly patients (≥ 75 years) compared to a young control group (≤ 60 years). METHODS: A retrospective cohort of 316 THAs performed between 2014 and 2017 was prospectively examined. In all patients a cementless, curved short stem and press-fit cup (Fitmore® stem; Allofit®/-S cup; both ZimmerBiomet, Warsaw, IN, USA) were implanted via a minimally-invasive anterolateral approach. Clinical and radiological outcome as well as rate of complications and revision were assessed. RESULTS: In total, 292 patients have been included for analysis of complications and revisions (Øfollow-up: 4.5 years) and 208 patients for clinical and radiological outcome (Øfollow-up: 4.4 years). Complication rate was significantly increased in elderly patients (13.7% vs. 5.8%, p = 0.023), while the revision rate was increased without statistical significance (5.2% vs. 2.2%, p = 0.169). Periprosthetic fractures occurred significantly higher in the elderly patients (5.2% vs. 0.7%; p = 0.026). Both groups showed a comparable clinical outcome in the Harris Hip Score (93.7 vs. 91.9; p = 0.224), Oxford Hip Score (44.5 vs. 43.7; p = 0.350), Forgotten Joint Score (81.7 vs. 81.5; p = 0.952) and WOMAC (7.4 vs. 9.3; p = 0.334). CONCLUSION: Cementless short stem total hip arthroplasty shows a comparable clinical and radiological outcome in patients over 75 years of age compared to younger patients under 60 years of age. However, cementless shorts stem THA shows an increased rate of overall complications and periprosthetic fractures in elderly patients over 75 years of age. Cemented fixation of the femoral component should be considered in patients over 75 years of age. LEVEL OF EVIDENCE: III Case-controlled study. TRIAL REGISTRATION: Observational study without need for trial registration due to ICMJE criteria.

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OBJECTIVE: The incidence of periprosthetic fractures after total hip arthroplasty using a short tapered-wedge stem is high. Callus formation preceding this fracture, which indicates postoperative stress fracture around the stem, has been reported. However, previous studies on postoperative callus are limited. Hence, the current study aimed to evaluate the prevalence and risk factors of postoperative callus after total hip arthroplasty with a short tapered-wedge stem. MATERIALS AND METHODS: This retrospective study included 127 patients who underwent total hip arthroplasty using a cementless short tapered-wedge stem. The depth of stem insertion was measured as the distance from the lateral corner of the stem to the most medial point of the lesser trochanter along the body axis. Postoperative callus was defined as a bridging callus on the lateral femoral cortex at the distal end of the porous coating of the stem. Plain radiography was performed before surgery and immediately and at 1, 3, and 6 months after surgery to assess postoperative callus. Univariate and multivariate logistic regression analyses were performed to identify the risk factors for PC. RESULTS: In total, 60 (47.2%) of 127 patients presented with postoperative callus. Multivariate logistic regression analysis with postoperative callus as the dependent variable revealed that the stem depth at 1 month after total hip arthroplasty (odds ratio, 1.14; 95% confidence interval, 1.04-1.24, p = 0.002) was a significant and independent risk factor of postoperative callus. CONCLUSION: Deep insertion of a short tapered-wedge stem is a risk factor for postoperative callus.

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Purpose: Obesity is prevalent, with nearly one-third of the world's population being classified as obese. In patients with high body mass index (BMI)/body mass undergoing total knee arthroplasty (TKA), there is an increase in strain placed on the implant fixation interfaces. As such, component fixation is a potential concern when performing TKA in the obese patient. To address the growing concerns around the longevity of implant fixation, some have advocated cementless over cemented fixation. However, there is no clear consensus on whether a cementless fixation has more favourable outcomes. The aim of this paper was to present a systematic review and meta-analysis of the existing evidence to establish if cementless TKA has a lower rate of aseptic loosening in high BMI patients when compared to cemented TKA procedures. Methods: A systematic review was performed, and the following databases Medical Literature Analysis and Retrieval System Online (1946 to date), PubMed (1966 to date) and Excerpta Medica Database (1974 to date) were searched. All studies comparing cementless to cemented TKA in patients with BMI > 30 were considered. Meta-analysis compared aseptic loosening and all-cause revision between cemented and uncemented implant use in BMI > 30 patients. Results: The search returned 91 articles in total; after duplicates were removed, the yield was 44 studies. Of the remaining studies that were assessed, three studies met the inclusion criteria for meta-analysis. The pooled odds ratio for all-cause revisions was 0.17 (95%, 0.08-0.36) in favour of uncemented implants (p < 0.01). The pooled odds ratio for aseptic loosening was 0.15 (95% confidence interval, 0.02-0.90) in favour of uncemented implants (p = 0.04). Conclusions: Meta-analysis demonstrated a significant decrease in all-cause revisions and revisions for aseptic loosening when using uncemented fixation in high BMI patients when compared to the use of cemented implants. Level of Evidence: The level of evidence is 1 for our systematic review.

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Background: This study aimed to investigate the relationship between 3-dimensional (3D) alignment and postoperative bone mineral density (BMD) changes with Accolade II tapered wedge stems, which have a different proximal shape from other tapered wedge stems, up to 5 years after primary total hip arthroplasty. Methods: We retrospectively analyzed the hips of 89 patients who underwent total hip arthroplasty using the second-generation proximally coated cementless stem (Accolade II; Stryker Orthopedics, Mahwah, NJ) at our institution from 2014 to 2018 over a 5-year follow-up. We evaluated the relationship between stem alignment, measured using 3D-templating software, and BMD changes in the 7 Gruen zones and compared the data with those from a former study using other short taper-wedge stems. Results: BMDs in zones 1 and 7 continued to decrease gradually every year after surgery, and BMD in zone 7 showed the largest decrease (21%) from baseline over 5 years. No correlation was found between stem alignment (varus/valgus, flexion/extension, and anteversion/retroversion) and changes in BMD in each zone over 5 years. Conclusions: Our data showed no correlation between 3D stem alignment and changes in BMD in each Gruen zone over 5 years. This suggests that the Accolade II stem may fit better into any shape of the proximal medullary canal because of its unique characteristics.

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INTRODUCTION: Early reverse total shoulder arthroplasty (RTSA) designs demonstrated high glenoid baseplate complication and revision rates. While contemporary designs have reduced the incidence of glenoid baseplate failures, there are reports of elevated failure risks in RTSA with glenoid bone grafting within the first 2 years. This study aims to evaluate the incidence and etiology of aseptic glenoid baseplate failure with a contemporary central screw baseplate. The null hypothesis is that majority of the baseplate failure occurs within the first 2 years and use of glenoid bone grafting does not lead to higher risk of baseplate failure. METHODS: In 2014 - 2019, 753 consecutive patients who underwent primary RSA using the same inlay press-fit humeral stem and monoblock central screw baseplate were retrospectively reviewed. Fracture and septic arthropathy cases were excluded. All patients underwent preoperative radiographic and computed tomography evaluation. If there was significant glenoid erosion (Walch A2, B2, B3, C1, C2, E2, E3, and/or E4 variants), patient-specific structural glenoid bone grafting was performed. All patients underwent standardized radiographic follow-up and failure was strictly defined as any hardware breakage and/or shift in glenoid baseplate position. Failures were defined as "early" if occurring within 2 years and "late" if occurring greater than 2 years after surgery. Comparative analysis was performed to evaluate demographics, glenoid graft use, and graft union rates between the cohorts. RESULTS: There were 23 patients with baseplate failures (23/753, 3.0%) at mean of 23 months. Twenty-two failures (96%) occurred in patients who received structural glenoid bone grafting. Only 1 failure (0.2%) occurred when bone grafting was not indicated (p<0.001). The most common failure pattern was associated with B2 glenoid (16/23, 70%). There were 5 (22%) early failures and 18 (78%) late failures. There were no differences in any patient demographic characteristics between cohorts. All 5 early failures had graft nonunion and 4/5 occurred without trauma. In the 18 late failures , 9/18 (50%) occurred without trauma (p=0.135). Seventeen of these patients had glenoid grafting, of which 9/17 (53%) had graft nonunion. CONCLUSIONS: Contemporary RTSA glenoid baseplate designs have an acceptably low incidence of failure. However, the addition of structural bone graft to correct glenoid wear leads to higher aseptic baseplate failure rate. The majority of these patients suffer failure after the 2-year postoperative mark, highlighting the necessity of longer follow-up. Further analysis is necessary to quantify glenoid characteristics (severity of glenoid erosion, critical size of graft) associated with failure.

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BACKGROUND: The present study aimed to identify the risk factors of periprosthetic femoral fracture (PFF) after cementless total hip arthroplasty and rank them based on importance. METHODS: The age, sex, body mass index (BMI), osteoporosis, canal flare index (CFI), canal bone ratio (CBR), canal calcar ratio (CCR), stem design, and stem canal fill ratio (P1, P2, P3, and P4) of the proximal femoral medullary cavity of 111 total hip arthroplasty patients who had PFF and 388 who did not have PFF were analyzed. Independent-samples student t-tests were used for continuous variables, and Chi-square tests were used for categorical variables. The importance rankings of influencing factors were assessed using a random forest algorithm. Dimensionally reduced variables were then incorporated into a binary logistic regression model to determine the PFF-related risk factors. RESULTS: The mean age, BMI, CBR, CCR, and incidence of osteoporosis were higher in cases of PFF (all P < .001), while the mean CFI, P1, P2, P3, and P4 were lower in cases of PFF (P < .001, P = .033, P = .008, P < .001, and P < .001, respectively). Additionally, the stem design was also statistically associated with PFF (P < .001). Multivariate logistic regression revealed that advanced age, higher BMI, osteoporosis, stem design, lower CFI, higher CBR, higher CCR, lower P1, lower P2, lower P3, and lower P4 were the risk factors of PFF (P < .001, P < .001, P < .001, P < .001, P < .001, P = .010, P < .001, P = .002, P < .001, P < .001, and P = .007, respectively). The ranked importance of the risk factors for PFF was P3, CFI, osteoporosis, CBR, age, P4, P1, stem design, CCR, BMI, and P2. CONCLUSIONS: Lower P3, lower CFI, osteoporosis, higher CBR, advanced age, lower P4, lower P1, stem design, higher CCR, higher BMI, and lower P2 increased the risk of PFF.

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BACKGROUND: The use of long stems for severe femoral bone defects is suggested by many scholars, but it is associated with further bone loss, intraoperative fracture, increased surgical trauma, and complications. With better bone retention, simple and quick surgical procedures, and minimal complications, the short cementless stems with a tapered rectangular shape may be an alternative for femoral revision. This study aimed to evaluate the results of this type of stem in treating selected Paprosky II-IV bone defects. METHODS: This retrospective study included 73 patients (76 hips involved) who underwent conservative femoral revision using the short cementless stems with a tapered rectangular shape between January 2012 and December 2020. The preoperative femoral bone defects were identified as follows: 54 cases of type II, 11 cases of type IIIA, 7 cases of type IIIB, and 4 cases of type IV. Indications for revision included aseptic loosening (76.3%) and prosthetic joint infection (23.7%). Six cementless stems with a tapered rectangular shape from three companies were used in all patients. Among them, SLR-Plus, SL-Plus MIA, and Corail stems were employed in most patients (40.8%, 23.7%, and 17.1%, respectively). The average length of these stems measured 171.7 mm (SD 27 mm; 122-215 mm). Radiographic results, Harris hip scores (HHS), complications, and survivorship were analyzed. The follow-up lasted for 7 years on average (range 3-11 years). RESULTS: The subsidence was observed in three hips (3.9%), and all stems achieved stable bone ingrowth. Proximal femoral bone restoration in the residual osteolytic area was found in 67 hips (88.2%), constant defects in nine hips (11.8%), and increasing defects in 0 cases. There was no evidence of stem fractures and stem loosening in this series. The mean HHS significantly improved from 32 (range 15-50) preoperatively to 82 (range 68-94) at the last follow-up (t = - 36.297, P < 0.001). Five hips developed prosthesis-related complications, including three infection and two dislocation cases. The mean 5- and 10-year revision-free survivorships for any revision or removal of an implant and reoperation for any reason were 94.6% and 93.3%, respectively. Both mean 5- and 10-year revision-free survivorships for aseptic femoral loosening were 100%. CONCLUSION: Conservative femoral revision using short cementless stems with a tapered rectangular shape can provide favorable radiographic outcomes, joint function, and mid-term survivorship with minimal complications. Of note, a sclerotic proximal femoral bone shell with continued and intact structure and enough support strength is the indication for using these stems.

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Background: Initial stability of cementless stems is important to minimize the risk of subsidence, pain, and periprosthetic fracture after total hip arthroplasty (THA). Collared stems improve initial component stability when contacting the femoral calcar. Direct contact is not always achieved, and collared stem performance has not been studied in this context. We hypothesized that collared stems achieving direct contact would demonstrate reduced subsidence. Methods: A single-surgeon retrospective study of 482 consecutive primary THAs implanted between February 2020 and May 2023 using collared cementless stems was performed. The 2 cohorts included stems with initial collar-calcar contact vs stems without. Subsidence was evaluated by comparing intraoperative fluoroscopy to postoperative 8-week radiographs. Binary logistic regression identified independent risk factors for subsidence. Chi-square tests were used for categorical variables and t-tests for continuous variables. Results: Of stems, 63.9% achieved initial collar-calcar contact, while 36.1% did not. The rate (1.3% vs 19.0%; P < .001) and magnitude (0.02 mm, range 0-3 mm vs 0.35 mm, range 0-3 mm; P < .001) of subsidence were significantly higher among stems without initial contact. Stems without initial collar-calcar contact (P < .001) and male gender (P = .007) were independent risk factors for subsidence. Two patients with initial contact had nondisplaced calcar cracks and <3 mm of subsidence at 4 weeks, which healed with protected weight-bearing. Stem survivorship was 100% in both groups, with all achieving osteointegration and none needing revision. Conclusions: Excellent performance of collared cementless stems was observed at 8 weeks after primary THA. Initial collar-calcar contact lowered the risk and magnitude of minor subsidence but did not affect survivorship or fracture risk. Level of Evidence: Level III.