Above-Knee Amputation Following Chronically Infected Total Knee Arthroplasty: Patient-Reported Satisfaction and Functional Outcomes.

INTRODUCTION: Periprosthetic joint infection (PJI) that arises following total knee arthroplasty (TKA) can usually be resolved through surgical and antimicrobial therapy. However, in approximately 5% of cases, an infection that is chronic and persistent will require treatment by above-knee amputation (AKA). This study seeks to provide an enhanced understanding of patient functionality and satisfaction following this devastating complication of one of the most commonly performed surgeries in the world. METHODS: A retrospective chart review of all patients who underwent an AKA as a result of PJI following TKA at our center between January 2000 and November 2023 was performed. Patients completed a post-TKA AKA functionality and satisfaction questionnaire, as well as the 12-Item Short Form Survey (SF-12). Of 27 eligible patients, 14 were contacted by phone for follow-up, 6 were deceased, 6 could not be reached, and 1 declined participation. The mean age at AKA was 62 years old (range, 43 to 85). Patients had an average of 5.5 procedures (range, 3 to 8) between primary TKA and AKA. The average follow-up time post-AKA was 38.5 months (range, 12 to 102). RESULTS: Of the patients, 85.7% were satisfied with their AKA, 85.7% would choose AKA again, and 71.4% would have proceeded with AKA earlier in retrospect. Average SF-12 physical and mental component scores were 37.1 and 50.6, respectively. DISCUSSION: Despite important limitations in functional and ambulatory status, the vast majority of patients who underwent an AKA following an infected TKA are satisfied with their amputation and would choose this treatment modality again if necessary, with many indicating they would do so at an earlier time point. In light of these results, the option of amputation should, when medically indicated, be discussed in a sensitive, but timely manner with patients undergoing treatment for recalcitrant PJI.

Intraoperative and Postoperative Outcomes of Patients Undergoing Total Knee Arthroplasty With Prior Anterior Cruciate Ligament Reconstruction: A Matched Cohort Analysis.

Background: Previous anterior cruciate ligament (ACL) injury is a risk factor for the development of knee osteoarthritis. Despite advances in ACL reconstruction (ACLR) techniques, many patients with history of ACLR develop end-stage osteoarthritis necessitating total knee arthroplasty (TKA). The purpose of this study was to investigate the impact of prior ACLR on intraoperative and postoperative outcomes of TKA. Methods: This was a single-centre matched cohort study of all patients with prior ACLR undergoing primary TKA from January 2000 to May 2022. Patients were matched 1:1 to patients undergoing TKA with no prior ACL injury based on age, sex, and body mass index. Outcomes investigated included TKA procedure duration, soft-tissue releases, implant design, and complications requiring reoperation. Results: Forty-two ACLR patients were identified and matched to controls. Mean follow-up was 6.8 years and 5.0 years in the ACLR and control cohorts, respectively (P = .115). ACLR patients demonstrated longer procedure durations (122.8 minutes vs 87.0 minutes, P < .001) and more frequently required soft-tissue releases (40.5% vs 14.3%, P = .007), stemmed implants (23.8% vs 4.8%, P = .013), and patellar resurfacing (59.5% vs 26.2%, P = .002). There were no significant differences in postoperative clinical or surgical outcomes between groups. Ten-year implant survivorship was 92% and 95% in the ACLR and control cohorts, respectively (P = .777). Conclusions: TKA is an effective procedure for the management of end-stage osteoarthritis with prior ACLR. The care team should be prepared for longer operative times and the utilization of advanced techniques to achieve satisfactory soft-tissue balance and implant stability.

Total Knee Arthroplasty With Robotic and Augmented Reality Guidance: A Hierarchical Task Analysis.

Background: Total knee arthroplasty (TKA) is a commonly performed procedure that has traditionally utilized reproducible steps using a set of mechanical instruments. The number of TKAs performed using robotic assistance is increasing, and augmented reality (AR) navigation systems are being developed. Hierarchical task analysis (HTA) aims to describe the steps of a specific task in detail to reduce errors and ensure reproducibility. The objective of this study was to develop and validate HTAs for conventional, robotic-assisted, and AR-navigated TKA. Methods: The development of HTAs for conventional TKA involved an iterative review process that incorporated the input of 4 experienced arthroplasty surgeons. The HTAs were then adapted for robotic-assisted and AR-navigated TKA by incorporating specific steps associated with the use of these systems. The accuracy and completeness of the HTAs were validated by observing 10 conventional and 10 robotic-assisted TKA procedures. Results: HTAs for conventional, robotic-assisted, and AR-navigated TKA were developed and validated. The resulting HTAs provide a comprehensive and standardized plan for each procedure and can aid in the identification of potential areas of inefficiency and risk. Robotic-assisted and AR-navigated approaches require additional steps, and there are an increased number of instances where complications may occur. Conclusions: The HTAs developed in this study can provide valuable insights into the potential pitfalls of robotic-assisted and AR-navigated TKA procedures. As AR-navigation systems are developed, they should be optimized by critical analysis using the developed HTAs to ensure maximum efficiency, reliability, accessibility, reduction of human error, and costs.

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.

Good Short-Term Survivorship of Constrained Condylar Revision Knee Implants With Medial Pivot Kinematics: A Level IV Retrospective Study.

BACKGROUND: The need for revision total knee arthroplasty surgery is increasing worldwide, and, in many cases, a constrained implant is required to provide joint stability. The purpose of this study was to examine the early loosening and functional outcome of a novel constrained condylar (CCK) revision total knee system designed to have medial pivot (MP) kinematics. METHODS: A retrospective cohort study was performed, collecting clinical data from all patients who underwent revision total knee arthroplasty using a novel MP CCK system with a minimum four-year clinical follow-up. Patient demographics, survivorship, complications, and Forgotten Joint Score were analyzed based upon chart review. RESULTS: There were 49 patients available for follow-up, who had a 100% survivorship free of aseptic loosening. All-cause revision survivorship was 92%. There were 4 patients who subsequently underwent rerevision. The causes for rerevision included periprosthetic joint infection in 2 patients, coronal plane instability in one patient, and a traumatic knee dislocation in one patient. There were 45 patients who completed the Forgotten Joint Score, who had an average of 49.8 (± 32.8, range 6.25 to 100). CONCLUSIONS: At 4 years, mid-term follow-up, this novel CCK revision total knee system designed to have MP kinematics had good patient-reported outcomes with no revision for aseptic loosening. Future studies should evaluate the mid- and long-term survivorship of this innovative implant.

Long-term outcomes of the Nexgen© posterior stabilized knee: minimum 15 year follow-safe and effective.

PURPOSE: Studying long-term survivorship and functional outcomes for specific prostheses is critical for elucidating areas in need of design improvement. This study reports the long-term of the NexGen Posterior Stabilized (PS) Total Knee implant (TKA) (Zimmer Biomet, Warsaw IN) Performed by a single surgeon. METHODS: Data from patients treated with the NexGen PS TKA between January 2003 and December 2005 with a minimal follow-up of 15 years was collected from a prospectively collected database. Survivorship rates and Oxford Knee Scores (OKS) were obtained for those patients available for follow-up. RESULTS: Ninety-five patients met the inclusion criteria during the study period. OKS was available for 44 (46%) patients. Ten patients required revision surgery (10.52%). Implant-specific survivorship of all cases that were reviewed was 98%. Survivorship of implants in patients that we were able to reach, or deceased patients was 93%. The average Oxford Knee Score was 39.1 (14-48. SD ± 7.70) with 48 being the maximal score. CONCLUSION: Despite some concerns about durability of this implant, good longevity and function was demonstrated. At a minimum of 15 years follow-up in this cohort. Given these results design features of this system should be considered for future generations of implants.

Quality indicators in primary elective total hip and knee arthroplasty.

PURPOSE: Total hip arthroplasty (THA) and total knee arthroplasty (TKA) represent a significant portion of healthcare spending and are high-priority for quality improvement initiatives. This study aims to develop quality indicators (QIs) in the care of primary elective THA and TKA patients. These QIs serve a number of purposes including documentation of the quality of care, objective comparisons of institutions/providers, facilitating pay-for-performance initiatives, and supporting accountability, regulation, and accreditation. METHODS: A guideline-based approach, initially described by Kötter et al., was utilized. Eight clinical practice guidelines (CPGs) were evaluated for candidate indicators (CIs). CIs with high-quality evidence and consensus statements were extracted. Eighteen additional CIs were included from previous work that evaluated quality improvement databases. Each CI and supporting evidence was submitted for independent review by an expert panel. The RAND Corporation-University of California, Los Angeles (RAND/UCLA) appropriateness methodology was utilized and items were rated based on validity, reliability, and feasibility of measurement. After two rounds of ratings and ranking, a final ranked list of QIs was obtained. RESULTS: Fifty-six CIs were identified from the literature and CPGs or proposed by the expert panel. Two rounds of voting resulted in 12 total QIs that were deemed appropriate measures of high-quality care. The final 12 QIs were ranked by order of importance: use of peri-operative tranexamic acid, infusion of prophylactic antibiotics prior to inflation of tourniquet, appropriate post-operative venous thromboembolic prophylaxis, complication rate, rate of secondary procedure, readmission rate, early mobilization, average change of pre- to one year post-operative functional status, use of multimodal analgesia, use of neuraxial anesthesia, use of peri-articular injection in TKA, and use of pre-operative PO analgesia. CONCLUSION: This study is an expert opinion based on parameters observed in modern and high-quality academic settings. Twelve QIs are proposed to assess the quality of care in the peri-operative management of primary elective THA and TKA patients.

Clinical applications of augmented reality in orthopaedic surgery: a comprehensive narrative review.

PURPOSE: The development of augmented reality (AR) technology allows orthopaedic surgeons to incorporate and visualize surgical data, assisting the execution of both routine and complex surgical operations. Uniquely, AR technology allows a surgeon to view the surgical field and superimpose peri-operative imaging, anatomical landmarks, navigation guidance, and more, all in one view without the need for conjugate gaze between multiple screens. The aim of this literature review was to introduce the fundamental requirements for an augmented reality system and to assess the current applications, outcomes, and potential limitations to this technology. METHODS: A literature search was performed using MEDLINE and Embase databases, by two independent reviewers, who then collaboratively synthesized and collated the results of the literature search into a narrative review focused on the applications of augmented reality in major orthopaedic sub-specialties. RESULTS: Current technology requires that pre-operative patient data be acquired, and AR-compatible models constructed. Intra-operatively, to produce manipulatable virtual images into the user's view in real time, four major components are required including a camera, computer image processing technology, tracking tools, and an output screen. The user is provided with a heads-up display, which is a transparent display, enabling the user to look at both their natural view and the computer-generated images. Currently, high-quality evidence for clinical implementation of AR technology in the orthopaedic surgery operating room is lacking; however, growing in vitro literature highlights a multitude of potential applications, including increasing operative accuracy, improved biomechanical angular and alignment parameters, and potentially reduced operative time. CONCLUSION: While the application of AR systems in surgery is currently in its infancy, we anticipate rapid and widespread implementation of this technology in various orthopaedic sub-specialties.

Comparison of Single-Radius with Multiple-Radius Femur in Total Knee Arthroplasty: A Meta-Analysis of Prospective Randomized Controlled Trials.

BACKGROUND: Whether there was clinical superiority for the single-radius prosthesis over the multi-radius prothesis in total knee arthroplasty (TKA) still remains to be clarified. We updated a meta-analysis including prospective randomized controlled trials (RCTs) to compare the clinical prognosis of patients receiving single-radius TKA (SR-TKA) or multi-radius TKA (MR-TKA). METHODS: We searched the databases of PubMed, Web of Science, EMBASE, Cochrane Library, MEDLINE for eligible RCTs. Two reviewers evaluated the study quality according to the Risk of Bias tool of the Cochrane Library and extracted the data in studies individually. The extracted data included the baseline data and clinical outcome. The baseline data include the author's name, country, and year of included studies, the name of knee prosthesis used in studies, sample size, follow-up time, and BMI of patients. The clinical data comprised primary indicators including postoperative knee range of motion (ROM), sit-to-stand rest, severe postoperative scorings, such as visual analog scale (VAS), American Knee Society knee score (AKS), Oxford knee scoring (OKS), and SF-36 Quality of Life Scale, as well as various secondary indicators of complications including anterior knee pain, postoperative infection, aseptic prosthesis loosening, and prosthesis revision. The data analysis was performed using Review Manager 5.3 software and STATA 12.0. The sensitivity analysis was performed using STATA 12.0. RESULTS: A total of 13 RCTs, along with 1720 patients and 1726 knees, were finally included in our present meta-analysis. We found that patients in SR-TKA group performed better in the sit-to-stand test (OR = 1.89, 95% CI: 1.05-3.41, p = 0.03) and satisfaction evaluation (OR = 3.27, 95% CI: 1.42-7.53, p = 0.005), which were only evaluated in two included RCTs. While no significant difference was found between SR-TKA and MR-TKA groups in terms of postoperative ROM, VAS scoring, AKS scoring, SF-36 scoring, OKS scoring, and various complications including anterior knee pain, postoperative infection, aseptic prosthesis loosening, and prosthesis revision. CONCLUSION: In conclusion, our present meta-analysis indicated that SR implants were noninferior to MR implants in TKA, and SR implants could be an alternative choice over MR implants, since patients after SR-TKA felt more satisfied and performed better in the sit-to-stand test, with no significant difference in complications between SR-TKA and MR-TKA groups. While more relevant clinical trials with long-term follow-up time and specific tests evaluating the function of knee extension mechanism should be carried out to further investigate the clinical performance of SR implants.

Distal femoral replacement or internal fixation for management of periprosthetic distal femur fractures: A systematic review.

BACKGROUND: The number of periprosthetic fractures above a total knee arthroplasty continues to increase. These fractures are associated with a high risk of morbidity and mortality. Techniques for addressing these fractures include open reduction internal fixation (ORIF) and revision arthroplasty, including distal femoral replacement (DFR). The primary aim of this review is to compare mortality and reoperation rates between ORIF and DFR when used to treat periprosthetic distal femur fractures. METHODS: A systematic review including MEDLINE, Embase and Cochrane Library databases was completed from inception to April 10, 2021. Studies including a comparator cohort were meta-analyzed. RESULTS: Fourteen studies were identified for inclusion, of which, five had sufficient homogeneity for inclusion in a meta-analysis. 30-day and 2-year mortality was 4.1% and 14.6% in the DFR group. There was no statistically significant difference between ORIF and DFR (log Odds-Ratio (OR) = -0.14, 95 %CI: -0.77 to 0.50). The reoperation rate in the DFR group was 9.3% versus 14.8% for ORIF, with no difference between groups (log OR = 0.10, 95 %CI: -0.59 to 0.79). There was no difference in rates of deep infection (log OR = 0.22, 95 %CI: -0.83 to 1.28). Direct comparison of functional outcomes was not possible, though did not appear significant. CONCLUSION: DFR in the setting of periprosthetic distal femur fractures is equivalent to ORIF with respect to mortality and reoperation rate and thus a safe and reliable treatment strategy. DFR may be more reliable in complex fracture patterns where the ability to obtain adequate fixation is difficult.

Comparing Analgesia on an As-Needed Basis to Traditional Intravenous Patient-Controlled Analgesia Within Fast-Track Orthopedic Procedures: A Randomized Controlled Trial.

BACKGROUND: The aim was to determine if the use of intravenous patient-controlled analgesia (IVPCA) in a fast-track joint replacement program is associated with increased use of perioperative opioid consumption and increased length of hospital stay. DESIGN: A prospective, double-blind, randomized controlled trial. SETTINGS: Academic hospital. PARTICIPANTS/SUBJECTS: A total of 80 patients aged 18-85 years, with body mass index (BMI) 18-40, undergoing elective total knee arthroplasty were recruited. METHODS: Pre-operatively, patients received gabapentin, celecoxib, and acetaminophen. Peri-operatively, patients received spinal anesthesia with morphine and fentanyl, and periarticular local anesthetic administration by the surgeon. Postoperatively, 80 patients were randomized by a computer-generated sequence into IVPCA group (group A, n = 40) and non-IVPCA group (group B, n = 40). RESULTS: The primary outcome was 48-hour postoperative opioid consumption and length of hospital stay. Secondary outcomes included side effects of opioids, patient satisfaction, and pain scores. There was no significant difference within 48-hour postoperative opioid consumption (median 61.3 vs. 87.5, p = .181) and length of hospital stay (median 49.8 hours vs. 49.5 hours; p = .89) between the two groups. Also, there was no significant difference in patient satisfaction (median 5 in both groups), pain scores, and opioid-related side effects. CONCLUSIONS: IVPCA was associated with nonsignificant reduction in opioid exposure in elective total knee arthroplasty surgery within 48 hours. Neither group was superior in terms of length of hospital stay, opioid related side-effects, pain scores, and patient satisfaction.

Nerve Injuries in Total Knee Arthroplasty.

Nerve injury is one of the potential complications of total knee arthroplasty. The extent of the injury includes motor and sensory dysfunction, either temporary or permanent. Although the consequences of nerve injury may be dramatic, the probability of occurrence during the course of primary knee arthroplasty is low, around 0.12% to 0.4%. Local dressing removal and knee flexion are imperative, and the initial investigations include ultrasound or MRI and nerve conduction studies. The extent of recovery depends on the type and severity of the initial nerve palsy; however, most patients are expected to have at least a partial recovery.

Cemented Versus Hybrid Technique of Fixation of the Stemmed Revision Total Knee Arthroplasty: A Literature Review.

Stems are required during revision total knee arthroplasty to bypass damaged periarticular bone and transfer stress to healthier diaphyseal bone. The mode of stem fixation, whether fully cemented or hybrid, remains controversial. Improvements in surgical technique and implant and instrument technology have improved our ability to deal with many of the challenges of revision total knee arthroplasty. Recent publications that reflect contemporary practice has prompted this review of literature covering the past 20 years to determine whether superiority of one fixation mode over the other can be demonstrated. We reviewed single studies of each type of fixation, studies directly comparing both types of fixation, systematic reviews, international registry data, and studies highlighting the pros and cons of each mode of stem fixation. Based on the available literature, we conclude that using both methods of fixation carries comparable outcomes with marginal superiority of the hybrid fixation method, which is of nonstatistical significance, although on an individual case basis, all fixation methods should be kept in mind and the appropriate method implemented when suitable.

A Comparison of Acute Complications and Mortality Between Geriatric Knee and Hip Fractures: A Matched Cohort Study.

INTRODUCTION: To compare acute complication and mortality rates for operatively treated, closed, isolated, low-energy geriatric knee fractures (distal femur [DFF] or tibial plateau [TPF]) with hip fractures (HFs). METHODS: This is a retrospective cohort study using the American College of Surgeons National Surgical Quality Improvement Program. We identified all patients ≥ 70 years from 2011 to 2016 who underwent surgery for DFF, TPF, or HF. We recorded patient demographics, functional status, complications, and mortality. We matched DFF:TPF:HF patients on a 1:1:10 ratio based on age, sex, body mass index, baseline functional status, and comorbidity. We used the chi square, Fisher exact, and Mann Whitney U tests to compare unadjusted differences between groups and multivariable logistic regression to compare the risk of complications, readmission, or death while adjusting for relevant covariates. RESULTS: When compared with HF, patients in the DFF and TPF groups had longer length of stay and time to index surgery and were more likely to be discharged home. The rate of deep vein thrombosis was significantly higher in the TPF group (TPF = 3.9%, DFF = 1.3%, and HF = 1.2%, P = 0.005). CONCLUSION: Geriatric knee fractures pose a similar risk of acute complications, mortality, and readmission compared with patients with HF. Future studies investigating strategies to decrease risk in this patient cohort are warranted. LEVEL OF EVIDENCE: Therapeutic Level III.

Reducing Acute Hospitalization Length of Stay After Total Knee Arthroplasty: A Quality Improvement Study.

BACKGROUND: The introduction of bundled funding for total knee arthroplasty (TKA) has motivated hospitals to improve quality of care while minimizing costs. The aim of our quality improvement project is to reduce the acute hospitalization length of stay to less than 2 days and decrease the percentage of TKA patients discharged to inpatient rehabilitation using an enhanced recovery after surgery bundle. METHODS: This study used a before-and-after design. The pre-intervention period was January to December 2017 and the post-intervention period was January 2018 to August 2019. A root cause analysis was performed by a multidisciplinary team to identify barriers for rapid recovery and discharge. Four new interventions were chosen as part of an improvement bundle based on existing local practices, literature review, and feasibility analysis: (1) perioperative peripheral nerve block; (2) prophylactic antiemetic medication; (3) avoidance of routine preoperative urinary catheterization; and (4) preoperative patient education. RESULTS: The pre-intervention and post-intervention groups included 232 and 383 patients, respectively. Mean length of stay decreased from 2.82 to 2.13 days (P < .001). The need for inpatient rehabilitation decreased from 20.2% to 10.7% (P = .002). Mean 24-hour oral morphine consumption decreased from 60 to 38 mg (P < .001). The percentage of patients experiencing moderate-to-severe pain and postoperative nausea and vomiting within the first 24 hours decreased by 25% and 15%, respectively (P < .001). Thirty-day emergency department visits following discharge decreased from 12.9% to 7.3% (P = .030). CONCLUSION: Significant improvements in the recovery of patients after TKA were achieved by performing a root cause analysis and implementing a multidisciplinary, patient-centered enhanced recovery after surgery bundle. LEVEL OF EVIDENCE: Level III.

Endoglin Level Is Critical for Cartilage Tissue Formation In Vitro by Passaged Human Chondrocytes.

Transforming growth factor beta (TGFß) signaling is required for in vitro chondrogenesis. In animal models of osteoarthritis (OA), TGFß receptor alterations are detected in chondrocytes in severe OA cartilage. It is not known whether such changes are dependent on the grade of human OA and if they affect chondrogenesis. Thus, the purpose of this study was to determine if human OA chondrocytes obtained from low-grade or high-grade disease could form cartilage tissue and to assess the role of the co-receptors, endoglin (ENG) and TGFß receptor 3 (TGFBRIII), in the regulation of this tissue generation in vitro. We hypothesized that the grade of OA disease would not affect the ability of cells to form cartilage tissue and that the TGFß co-receptor, ENG, would be critical to regulating tissue formation. Chondrocytes isolated from low-grade OA or high-grade OA human articular cartilage (AC) were analyzed directly (P0) or passaged in monolayer to P2. Expression of the primary TGFß receptor ALK5, and the co-receptors ENG and TGFßRIII, was assessed by image flow cytometry. To assess the ability to form cartilaginous tissue, cells were placed in three-dimensional culture at high density and cultured in chondrogenic media containing TGFß3. ENG knockdown was used to determine its role in regulating tissue formation. Overall, grade-specific differences in expression of ALK5, ENG, and TGFßRIII in primary or passaged chondrocytes were not detected; however, ENG expression increased significantly after passaging. Despite the presence of ALK5, P0 cells did not form cartilaginous tissue. In contrast, P2 cells derived from low-grade and high-grade OA AC formed hyaline-like cartilaginous tissues of similar quality. Knockdown of ENG in P2 cells inhibited cartilaginous tissue formation compared to controls indicating that the level of ENG protein expression is critical for in vitro chondrogenesis by passaged articular chondrocytes. This study demonstrates that it is not the grade of OA, but the levels of ENG in the presence of ALK5 that influences the ability of human passaged articular chondrocytes to form cartilaginous tissue in vitro in 3D culture. This has implications for cartilage repair therapies. Impact statement These findings are important clinically, given the limited availability of osteoarthritis (OA) cartilage tissue. Being able to use cells from all grades of OA will increase our ability to obtain sufficient cells for cartilage repair. In addition, it is possible that endoglin (ENG) levels, in the presence of ALK5 expression, may be suitable to use as biomarkers to identify cells able to produce cartilage.

Superior patient satisfaction in medial pivot as compared to posterior stabilized total knee arthroplasty: a prospective randomized study.

PURPOSE: Medial pivot (MP) total knee arthroplasty (TKA) aims to restore native knee kinematics due to highly conforming medial tibio-femoral articulation with survival comparable to contemporary knee designs. Posterior stabilized (PS) TKAs use cam-post mechanism to restore native femoral rollback. However, there is conflicting evidence regarding the reported patient satisfaction with MP TKA designs when compared to PS TKAs. The primary aim of this study is to compare the patient satisfaction between MP and PS TKA and the secondary aim is to establish potential reasons behind any differences in the outcomes noted between these two design philosophies. METHODS: In this IRB-approved single surgeon, single centre prospective RCT, 53 patients (mean age 62 years, 42 women) with comparable bilateral end-stage knee arthritis undergoing simultaneous bilateral TKA were randomized to receive MP TKA in one knee and PS TKA in the contralateral knee. At 4 years post-surgery, all patients were assessed using Knee Society Score (KSS)-Satisfaction and -Expectation scores, and Oxford Knee Score (OKS). In addition, all the patients underwent standardized radiological and in vivo kinematic assessment. RESULTS: Patients were more satisfied with the MP TKA as compared to PS TKA: mean KSS-Satisfaction [34.5 ± 3.05 in MP and 31.7 ± 3.16 in PS TKAs (p < 0.0001)] and mean KSS-Expectation scores [12.5 ± 1.39 in MP TKAs and 11.2 ± 1.41 in PS TKAs (p < 0.0001)]. No significant difference was noted in any other clinical outcomes. The in vivo kinematics of MP TKAs was significantly better than those of PS TKAs. CONCLUSION: MP TKAs provide superior patient satisfaction and patient expectations as compared to PS TKA. This may be related to better replication of natural knee kinematics with MP TKA. LEVEL OF EVIDENCE: I.

Revision total knee arthroplasty for patellar dislocation in patients with malrotated TKA components.

PURPOSE: Patellar dislocation is a serious complication leading to patient morbidity following total knee arthroplasty (TKA). The cause can be multifactorial. Extensor mechanism imbalance may be present and result from technical errors such as malrotation of the implants. We sought to understand the reasons for post-arthroplasty patellar dislocation and the clinical outcomes of patients in whom it occurs. METHODS: This is a retrospective cohort study assessing the outcomes of revision surgery for patellar dislocation in patients with component malrotation in both primary and revision TKAs. Patient demographics, dislocation etiology, presurgical deformity, intraoperation component position, complications, reoperation, and Knee Society Scores (KSS) were collected. RESULTS: Twenty patients (21 knees) were identified. The average time from primary arthroplasty to onset of dislocation was 33.6 months (SD 44.4), and the average time from dislocation to revision was 3.38 months (SD 2.81). Seventeen knees (80.9%) had internal rotation of the tibial component and seven knees (33.3%) had combined internal rotation of both the femoral and tibial components. Fifteen knees (71.4%) were treated with a condylar constrained implant at the time of revision, and five knees were converted to a hinged prosthesis. The average follow-up time was 56 months. During this time, one patient (4.54%) had a recurrent dislocation episode, requiring further surgery. At final follow up, the mean KSS was 86.2. CONCLUSION: Revision TKA following patellar dislocation for patients with malrotated components was associated with high success rates. After revision surgery, patients had a low recurrence of patellar dislocation, low complication rates, and excellent functional outcomes.