The ROSA knee robotic system demonstrates superior precision in restoring joint line height and posterior condylar offset compared to conventional manual TKA: a retrospective case-control study.

PURPOSE: Variations in total knee arthroplasty (TKA) joint line height may lead to complications such as pain and altered joint mechanics, while posterior condylar offset (PCO) can influence knee stability. METHODS: Single-centre, single-surgeon retrospective analysis from December 2019 to May 2023 investigated primary unilateral TKA (Nexgen Legacy, Zimmer Biomet) in patients with knee osteoarthritis, using ROSA robotic system (raTKA) or conventional manual technique (mTKA). Joint line height and PCO were measured and compared in 182 raTKA and 144 mTKA patients. RESULTS: The groups were matched in age (p = 0.847) and sex distribution (p = 0.2). Excellent interobserver agreement (ICC ≥ 0.9). RaTKA mean joint line height difference was - 0.0001 mm (± 3.48, 95% CI - 0.509, 0.509) (p = 0.523), - 0.951 mm for mTKA (± 4.33, 95% CI - 1.664, - 0.237) (p = 0.009). RaTKA mean PCO difference was 0.52 mm (± 2.45, 95% CI 0.160, 0.880) (p = 0.005), 1.15 mm for mTKA (± 4.01, 95% CI - 1.496, 1.818) (p < 0.001). Mean difference in joint line height of 0.95 mm between groups was significant (p = 0.027), and for PCO, it was 0.63 mm, demonstrating tendency towards significance (p = 0.08). Mean absolute value in joint line height difference between groups was not significant (p = 0.235) but highly significant for PCO (p < 0.001). CONCLUSION: The ROSA knee robotic system can more accurately restore joint line height and PCO compared to conventional manual TKA. The improved degree of precision raTKA offers may be a vehicle for better Patient-Reported Outcome Measures, but further correlational studies are required.

Acetabular Reconstruction in a Rare Case of Ligamentum Teres Tenosynovial Giant Cell Tumour (TGCT) Causing Extensive Destruction.

Tenosynovial giant cell tumour (TGCT), previously called pigmented villonodular tenosynovitis (PVNS), is a rare benign, locally aggressive condition that primarily affects the synovial lining of large joints, such as the knee, the hip, and the ankle. TGCT of the hip joint is a relatively scarce entity, and its diagnosis is often challenging. This article reports a case of TGCT affecting the left acetabulum, the left femoral head, and the ligamentum teres of the hip joint in a 39-year-old woman who presented to our clinic three months after the onset of symptoms. The patient underwent a biopsy, computer tomography (CT), and magnetic resonance imaging (MRI). All tests were inconclusive. Total hip arthroplasty (THA) was subsequently performed, leading to healing of the lesion previously present. Following surgery, a second biopsy classified this lesion as TGCT. By sharing our experience with this rare manifestation, we aim to contribute to the growing body of knowledge on the diagnosis and management of TGCT, specifically when it occurs in the hip joint.

International Delphi Study on Wound Closure and Incision Management in Joint Arthroplasty Part 2: Total Hip Arthroplasty.

BACKGROUND: This modified Delphi study aimed to develop a consensus on optimal wound closure and incision management strategies for total hip arthroplasty (THA). Given the critical nature of wound care and incision management in influencing patient outcomes, this study sought to synthesize evidence-based best practices for wound care in THA procedures. METHODS: An international panel of 20 orthopedic surgeons from Europe, Canada, and the United States evaluated a targeted literature review of 18 statements (14 specific to THA and 4 related to both THA and total knee arthroplasty). There were 3 rounds of anonymous voting per topic using a modified 5-point Likert scale with a predetermined consensus threshold of ≥ 75% agreement necessary for a statement to be accepted. RESULTS: After 3 rounds of voting, consensus was achieved for all 18 statements. Notable recommendations for THA wound management included (1) the use of barbed sutures over non-barbed sutures (shorter closing times and overall cost savings); (2) the use of subcuticular sutures over skin staples (lower risk of superficial infections and higher patient preferences, but longer closing times); (3) the use of mesh-adhesives over silver-impregnated dressings (lower rate of wound complications); (4) for at-risk patients, the use of negative pressure wound therapy over other dressings (lower wound complications and reoperations, as well as fewer dressing changes); and (5) the use of triclosan-coated sutures (lower risk of surgical site infection) over standard sutures. CONCLUSIONS: Through a structured modified Delphi approach, a panel of 20 orthopedic surgeons reached consensus on all 18 statements pertaining to wound closure and incision management in THA. This study provides a foundational framework for establishing evidence-based best practices, aiming to reduce variability in patient outcomes and to enhance the overall quality of care in THA procedures.

Collared versus collarless hydroxyapatite-coated stems for primary cementless total hip arthroplasty; a systematic review of comparative studies. Is there any difference in survival, functional, and radiographic outcomes?

INTRODUCTION: This systematic review aims to critically assess the literature comparative studies investigating collared and collarless Corail stem in primary total hip arthroplasty (THA) to find differences in revision rates, radiographic and clinical outcomes, and postoperative complications between these two types of the same stem. METHODS: Eligible studies were found by searching PubMed, Science Direct/Scopus, and the Cochrane Database of Systematic Reviews from conception till May 2023. The PRISMA guidelines were followed. The investigation encompassed randomized controlled trials, case series, comparative, cohort, and observational studies that assessed at least one comparative outcome or complication between collared and collarless Corail stems. RESULTS: Twelve comparative studies with 90,626 patients undergoing primary THA were included. There were 40,441 collared and 58,543 collarless stems. The follow-up ranged from 12 to 360 months. Our study demonstrated no significant difference in stem revision relative risk (RR = 0.68; 95% confidence interval (CI), 0.23, 2.02; p = 0.49), number of radiolucent lines (RR = 0.3; 95% CI, 0.06, 2.28; p = 0.29) and overall complication risk (RR = 0.62; 95% CI, 0.22, 1.76; p = 0.37) between collared and collarless stems. The collared stems demonstrated significantly lesser subsidence (mean difference: 1.01 mm; 95% CI, -1.77, -0.25; p = 0.009) and risk of periprosthetic fractures (RR = 0.52; 95% CI, 0.29, 0.92; p = 0.03). CONCLUSION: The comparative studies between collared and collarless stem groups showed similar survival and overall complication rates and functional outcomes. The similar revision rates between groups make the impact of higher subsidence for collarless stems uncertain. The lower risk of periprosthetic fractures in the collared stems group must be clarified further but could be related to increased rotational stability.

Primary Staged Bilateral Total Hip Arthroplasty in a Patient With Short Stature and Hartofilakidis Type I Developmental Dysplasia of the Hip.

Syndromes associated with osteochondrodysplasia, short stature, and DDH are rarely reported in the literature. Total hip arthroplasty (THA) in such cases is a complex procedure with a high rate of complications and difficulties. In this case report, we describe the staged bilateral complex primary THA of a patient with the rare occurrence of a syndrome involving osteochondrodysplasia and DDH, highlighting the surgical challenges and importance of the right prosthesis selection.

International Delphi Study on Wound Closure and Dressing Management in Joint Arthroplasty: Part 1: Total Knee Arthroplasty.

BACKGROUND: The purpose of this modified Delphi study was to obtain consensus on wound closure and dressing management in total knee arthroplasty (TKA). METHODS: The Delphi panel included 20 orthopaedic surgeons from Europe and North America. There were 26 statements identified using a targeted literature review. Consensus was developed for the statements with up to three rounds of anonymous voting per topic. Panelists ranked their agreement with each statement on a five-point Likert scale. An a priori threshold of ≥ 75% was required for consensus. RESULTS: All 26 statements achieved consensus after three rounds of anonymous voting. Wound closure-related interventions that were recommended for use in TKA included: 1) closing in semi-flexion versus extension (superior range of motion); 2) using aspirin for venous thromboembolism prophylaxis over other agents (reduces wound complications); 3) barbed sutures over non-barbed sutures (lower wound complications, better cosmetic appearances, shorter closing times, and overall cost savings); 4) mesh-adhesives over other skin closure methods (lower wound complications, higher patient satisfaction scores, lower rates of readmission); 5) silver-impregnated dressings over standard dressings (lower wound complications, decreased infections, fewer dressing changes); 6) in high-risk patients, negative pressure wound therapy over other dressings (lower wound complications, decreased reoperations, fewer dressing changes); and 7) using triclosan-coated over non-antimicrobial-coated sutures (lower risks of surgical site infection). CONCLUSIONS: Using a modified Delphi approach, the panel achieved consensus on 26 statements pertaining to wound closure and dressing management in TKA. This study forms the basis for identifying critical evidence supported by clinical practice for wound management to help reduce variability, advance standardization, and ultimately improve outcomes during TKA. The results presented here can serve as the foundation for knowledge, education, and improved clinical outcomes for surgeons performing TKAs.

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review.

PURPOSE: Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data. METHODS: Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs. RESULTS: One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies. CONCLUSIONS: This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

Effectiveness of virtual reality compared to video training on acetabular cup and femoral stem implantation accuracy in total hip arthroplasty among medical students: a randomised controlled trial.

PURPOSE: Virtual reality (VR) training effectiveness in improving hip arthroplasty surgical skills requires further evaluation. We hypothesised VR training could improve accuracy and the time taken by medical students compared to a control group with only video teaching. METHODS: This single-centre randomized controlled clinical trial collected data from March to June 2023. Surgically naïve volunteer undergraduate medical students performed three sessions on a VR training platform, either cup (VR-Cup=Control-Stem) or stem (VR-Stem=Control-Cup) implantation. The primary outcome was the mean difference between predefined cup inclination (60°) and stem anteversion (20°) compared to the actual implanted values in sawbones between VR and control groups. Secondary outcomes were task completion time and mistake number between the groups. RESULTS: A total of 101 students participated (VR-Cup 47, VR-Stem 54). Groups did not significantly differ concerning age (p = 0.879), gender (p = 0.408), study year (p = 0.938), previous VR use (p = 0.269) and baseline medical and procedural knowledge. The VR-Cup implanted the cup closer to the intended target (p < 0.001) and faster than the Control-Cup group (p = 0.113). The VR-Stem implanted the stem closer to the intended target (p = 0.008) but not faster than the Control-Cup group (p = 0.661). Stem retroversion was commoner in the Control-Stem than in the VR-Stem group (p = 0.016). CONCLUSIONS: VR training resulted in higher rates of accurate procedure completion, reduced time and fewer errors compared to video teaching. VR training is an effective method for improving skill acquisition in THA. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05807828.

Interventions used to mitigate muscle fatty degeneration following the repair of massive rotator cuff tears. A systematic review of animal studies.

BACKGROUND: Muscle fatty degeneration following rotator cuff tears has been unequivocally associated with poorer functional outcomes and increased risk for retear following rotator cuff repair. Promising results have emerged from animal studies, with the implementation of various interventions for biologic inhibition of this fatty muscle degeneration. The lack of high quality randomized human evidence on this topic, increases the impact of pooled results from animal literature. The aim of the present study was to systematically review the available published literature for animal studies evaluating the ability of several interventions used to mitigate muscle fatty degeneration following the repair of massive rotator cuff tears. PATIENTS AND METHODS: A comprehensive search was conducted on Pubmed, Scopus and Google Scholar, covering the period from conception until 16th April 2022. Datasets were stratified based on the type of intervention performed. SYRCLE risk of bias instrument was implemented for quality assessment of the included studies. RESULTS: Rotator cuff repair augmentation with Adipose derived stem cells (ADSC's), Mesenchymal stem cells (MSC's) and Nandrolone was effective against fatty infiltration, but less effective against muscle atrophy. More beneficial effect was shown by the utilization of Beige adipose tissue - Fibroadipogenic progenitors (BAT-FAP) stimulation, using either Amibregon or BAT-FAPs transplantation. Both provided good results in mitigating muscle atrophy, fatty infiltration and fibrosis. DISCUSSION: ADSC's, MSC's, Nandrolone and BAT-FAP stimulation may have a role in mitigating muscle fatty degeneration following rotator cuff tears. Large scale human studies are required to further elucidate their role in the clinical setting. LEVEL OF EVIDENCE: V; systematic review of pre-clinical studies.

Bisphosphonates' use and risk of aseptic loosening following total hip arthroplasty: a systematic review.

Purpose: The main indication of bisphosphonates (BPs) is osteoporosis treatment. However, there is growing interest in the peri- and postoperative use of BPs to mitigate total hip arthroplasty (THA) aseptic loosening (AL) risk. This systematic review aimed to evaluate the implant survival and the AL rate in patients with elective THA receiving BPs compared to those that do not receive BPs. Secondary outcomes included the comparison of revision rate, postoperative complications, and patients' functional scores. Methods: This systematic review was conducted under the PRISMA 2020 guidelines with a pre-registered PROSPERO protocol. Three engines and grey literature were searched up until May 2022. Randomized and nonrandomized controlled trials and comparative cohort studies assessing BP and control therapy impact on THA survival were included. Results: Twelve studies embraced the inclusion criteria. A total of 99 678 patients and 99 696 THAs were included; 10 025 patients received BPs (BP group), and 89 129 made up the control group. The overall revision and AL rates were lower in the BP group (2.17% and 1.85%) than in the control group (4.06% and 3.2%). Periprosthetic fracture (PPF) cases were higher in the BP group (0.24%) than in the control group (0.04%); however, the majority of PPF cases were derived from a single study. Further complication risk was similar between groups. Most studies reported comparable functional scores between groups. Conclusion: BP treatment after elective THA seems to reduce the overall revision and AL risk. Other complications' risk and functional scores were similar between groups. Further high-quality studies are needed to validate the results due to the multifactorial AL pathogenesis.

Complex Primary Total Knee Arthroplasty in a Young Patient With Neurofibromatosis Type One and Multidirectional Knee Instability: Technical Tips and Outcome.

Neurofibromatosis is an inherited disorder that causes skin discoloration and tumors. The musculoskeletal symptoms are specific, including bone deformities, dysplasia, joint instability, and osteoporosis. We present a rare case of a young patient with neurofibromatosis and multidirectional knee instability who underwent a successful complex primary knee replacement surgery. Stress right knee radiographs showed global joint instability with permanent anterior knee dislocation, excessively hypoplastic femoral condyles and patella, joint surfaces incongruency, and hypoplastic varus tibia, with intraluminal midshaft bone bridge causing severe stenosis. The patient could not walk, had an unstable recurvatum right knee, and used a wheelchair for her professional activities. The surgery involved a fully cemented rotating-hinged total knee arthroplasty with tibial and femoral stems. After three years of follow-up, the patient remains pain-free, fully ambulatory with no walking aids, a stable knee, a full range of motion, and no signs of aseptic loosening. This case highlights the decision-making difficulties and the significant surgical challenges faced during the operation.

Freeze-Drying Process for the Fabrication of Collagen-Based Sponges as Medical Devices in Biomedical Engineering.

This paper presents a systematic review of a key sector of the much promising and rapidly evolving field of biomedical engineering, specifically on the fabrication of three-dimensional open, porous collagen-based medical devices, using the prominent freeze-drying process. Collagen and its derivatives are the most popular biopolymers in this field, as they constitute the main components of the extracellular matrix, and therefore exhibit desirable properties, such as biocompatibility and biodegradability, for in vivo applications. For this reason, freeze-dried collagen-based sponges with a wide variety of attributes can be produced and have already led to a wide range of successful commercial medical devices, chiefly for dental, orthopedic, hemostatic, and neuronal applications. However, collagen sponges display some vulnerabilities in other key properties, such as low mechanical strength and poor control of their internal architecture, and therefore many studies focus on the settlement of these defects, either by tampering with the steps of the freeze-drying process or by combining collagen with other additives. Furthermore, freeze drying is still considered a high-cost and time-consuming process that is often used in a non-optimized manner. By applying an interdisciplinary approach and combining advances in other technological fields, such as in statistical analysis, implementing the Design of Experiments, and Artificial Intelligence, the opportunity arises to further evolve this process in a sustainable and strategic manner, and optimize the resulting products as well as create new opportunities in this field.

A Rare Case of Staphylococcus caprae-Caused Periprosthetic Joint Infection Following Total Hip Arthroplasty: A Literature Review and Antibiotic Treatment Algorithm Suggestion.

In this study, we discuss a case of a 59-year-old male who developed a periprosthetic joint infection (PJI) three months after a total hip arthroplasty (THA). The patient complained of groin and buttock pain, swelling, and high temperature. A palpable fluid collection, discomfort, edema, and elevated local temperature were present in the clinical examination. Laboratory analysis revealed elevated white blood cells, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). The preoperative joint aspiration came up positive for Staphylococcus caprae (S. caprae) infection. Diagnosis and pathogen identification were confirmed by histological examination of six tissue samples obtained during surgery. We initially performed early debridement, antibiotics, and implant retention (DAIR) followed by antibiotic therapy suggested by an infectious disease specialist. DAIR failed two months later, and we proceeded to a two-stage revision. Following surgery, the patient was treated with intravenous antibiotic combination therapy for three weeks and thereafter with oral antibiotics for three months. Four months down the line, the patient is free of symptoms, and the inflammatory markers are normal. Finally, we will proceed with the second stage of revision. This study highlights a very rare case of PJI infection by S. caprae, reviews the limited literature, and provides the available evidence for surgical and antibiotic management.

The learning curve to ROSA: cases needed to match the surgery time between a robotic-assisted and a manual primary total knee arthroplasty.

PURPOSE: Limited published data regarding the ROSA (Robotic Surgical Assistant) learning curve exist. This study evaluated the number of cases needed for an expert orthopaedic surgeon to master the ROSA system and match the operative time of robotic (raTKAs) and manual primary total knee arthroplasties (mTKAs). METHODS: This retrospective comparative cohort study included two hundred patients with primary knee osteoarthritis. The study group consisted of an expert surgeon's first 100 raTKAs. The control group included 100 patients that underwent mTKAs from the same surgeon during the same period. The consecutive cases in each group were divided into ten subgroups, each of 10 cases. The groups were comparable concerning age, sex, BMI and Kellgren-Lawrence classification. We compared each subgroup's operative time and complications in mTKA and raTKA groups. We performed a cumsum analysis to construct the ROSA learning curve. RESULTS: The first non-significant difference between the mTKAs and raTKAs operative times was observed in the subgroup of 62 to 71 cases. Till then, the operative time has been significantly lower for the mTKA than the raTKA group. The following groups of tens analysis (8th, 9th and 10th) showed no operative time difference between groups. The learning curve analysis demonstrated that the surgeon switched to the mastering phase from case 73 onwards. The two groups had no complication rate differences. CONCLUSION: Our study demonstrated that about 70 cases are necessary for a senior surgeon to balance operative time between mTKAs and raTKAs using the ROSA system.

Superior Transverse Atraumatic Reconstruction (STAR) approach provides a better-compared outcome to standard Direct Superior Approach (DSA): a matched, prospective comparative single-surgeon study.

INTRODUCTION: The Direct Superior Approach (DSA) is a muscle-sparing hip approach that does not protect the piriformis and the other short external rotators. We present a DSA modification we named STAR (Superior Transverse Atraumatic Reconstruction), which has DSA advantages but always preserves piriformis. Our study compared the early postoperative, radiological, and functional results of patients undergoing primary total hip arthroplasty (THA) through the STAR approach with a matched DSA group performed by a senior surgeon. METHODS: Each group, DSA, and STAR included 200 elective primary unilateral THAs performed by the surgeon between 2016-2017 and 2020-2021, respectively. Patients were included in both groups using the same inclusion criteria. Both groups were matched for age and sex. The same postoperative pain management, chemoprophylaxis, and physiotherapy protocols were followed in both groups. Two independent orthopaedic surgeons performed the clinical and radiological follow-up. RESULTS: The STAR group had significantly lower mean incision length (p = 0.042) and hospital stay (p = 0.002) than the DSA group. The mean intraoperative blood loss (p = 0.085) and the need for blood transfusion (p = 0.228) were less for the STAR than the DSA group. The mean postoperative functional scores improvement was significantly higher for the STAR than the DSA group at the end of the first and third postoperative months. CONCLUSIONS: The STAR approach offers earlier functional improvement, shorter hospital stay and less transfusion need than DSA for patients undergoing primary THA. Both approaches showed a limited complication risk and an outstanding acetabular and femoral access enabling the procedure.

Is thyroid disease associated with post-operative complications after total joint arthroplasty? A systematic review of the literature.

Background: This comprehensive systematic review aims to assess the literature regarding the risk of postoperative complications in patients undergoing total joint arthroplasty (TJA) with concomitant thyroid dysfunction. Methods: Studies were identified by searching PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, and ClinicalTrials.gov (end of search: May 2022). Inclusion criteria: Randomized control and case-control studies, cohort and observational clinical studies were included, which focused on postoperative complications and outcomes of patients undergoing TJA operations of major joints (knee, hip, ankle, elbow). All studies were assessed according to their level of evidence, the number and age of patients, and treatment complications. Analysis: Nine studies were included in this review that demonstrated a higher risk of postoperative anemia, perioperative blood loss, hemoglobin decrease, and transfusion rates in hypothyroid patients after TJA. Results: Hypothyroidism has been identified as a potential but modifiable risk factor for increased rates of deep venous thrombosis, acute kidney injury, pneumonia, and non-specified cardiac complications among hypothyroid patients who underwent TJA as well as increased rates of periprosthetic joint infection. No significant differences in the prosthesis-related mechanical complication rates have been calculated when comparing hypothyroid and euthyroid patients.

Medial pivot design does not yield superior results compared to posterior-stabilised total knee arthroplasty: a systematic review and meta-analysis of randomised control trials.

PURPOSE: The aim of this meta-analysis was a comparison between medial pivot (MP) and posterior-stabilised (PS) knee designs regarding functional and radiological outcomes as well as gait parameters. METHODS: A systematic literature search was conducted in PubMed, Cochrane Library, Science Direct and Clinical Trials.gov from conception up to April 2022, to identify eligible randomised control trials (RCTs). The extracted data were analysed according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) statement. RESULTS: Fifteen studies met inclusion criteria, enrolling 1101 patients who underwent 1242 total knee arthroplasties (TKAs). A total of 1158 TKAs (581 MP/577 PS) were included in the quantitative analysis. Mean follow-up ranged from 6 months up to 6.6 years. MP knees showed comparable range of motion (ROM) with PS design 1, 2 and 4 years postoperatively (p = 0.2, p = 0.25, p = 0.34, respectively). No statistical difference was found in patient-related outcome measures (PROMs) (p > 0.05). Mean walking speed (MWS), length of stay (LOS), radiographic alignment and complications rates were also similar between the two groups (p > 0.05). DISCUSSION: The present meta-analysis demonstrated that the theoretical biomechanical advantage of MP implants does not have a better impact on patient satisfaction compared to the traditional PS knees. LEVEL OF EVIDENCE: I.

Does stem profile have an impact on the failure patterns in revision total knee arthroplasty?

INTRODUCTION: Revision total knee arthroplasty (RTKA) has been increasing continuously. The results of RTKA still remain unsatisfactory. Failure patterns and risk factors in RTKA were thoroughly analyzed, with periprosthetic joint infections (PJI) and aseptic loosening remaining at the forefront of re-revision (ReRTKA) causes. While there is evidence that stem profile impacts the revisability of cemented implants, its association with the modes of RTKA failure is unknown. METHODS: 50 consecutive ReRTKA performed in a single orthopedic center during 2016-2017 were retrospectively analyzed. The cases were stratified according to age, sex, number of preexisting revisions, fixation technique, stem design and causes of re-revision. All explanted implants with conical vs. cylindrical stem profiles were compared. RESULTS: Mean age was 67 ± 11.5, and 54% were females. 72% of the cases had ≥ 3 previous revisions. 88% were full-cemented, 3% hybrid and 9% press-fit stems. 36% of the RTKA had conical, 58% cylindrical and 6% combined stem profiles. 92% of the RTKA components were removed. Removal causes were: PJI (52.2%), aseptic loosening (34.8%), implant malposition (9.8%), painful knee (1.1%) and instability (2.2%). While the overall RTKA failure patterns were equally distributed between conical and cylindrical stems, subgroup analysis of only cemented ReRTKA revealed a higher incidence of aseptic loosening within cylindrical stem profiles (46.7% vs. 25.7%, P = 0.05). CONCLUSION: Stem profile may have an impact on the process of aseptic loosening in cemented non-metaphyseal engaging RTKA, with cylindrical designs tending to worse outcomes than conical designs. Large cohort studies could provide more clarity on current observation.