Comparison of Conventional Technique with Suture Fixation and Subperiosteal Tight Pocket Technique on Revision Cochlear Implantation Rate.

Several fixation methods have been described to secure the cochlear implant's receiver/stimulator, but the optimal stabilization technique is still being debated. The aim of this study was to compare the conventional technique with suture fixation to the subperiosteal tight pocket technique in terms of revision cochlear implantation rate. A retrospective review was conducted on the medical records of 649 patients who underwent cochlear implantation. The study participants were divided into different groups regarding the applied surgery technique. The relationship between the fixation technique, revision rates, and the cause of revisions related to techniques was investigated. The overall revision rate was 2.9% (19 out of 649). There were 14 (3.5%) and 5 (2%) revision implantations in the subperiosteal tight pocket and conventional technique groups, respectively. The incidence of device failure was 2.5%, and it constituted the primary cause for revision surgery in both groups. Even though patients who had the subperiosteal tight pocket technique had a much higher rate of device failure, the results indicate that there was no significant difference between the groups, as evidenced by a P-value of .12. The conventional and subperiosteal tight pocket techniques can both be safely preferred with low revision rates in patients undergoing cochlear implantation.

Incidence and survival of multiply revised knee arthroplasties in Denmark 1998-2021: a nationwide register-based study.

PURPOSE: The primary aim of our study was to identify the absolute incidence and implant survival of multiply revised knee arthroplasties based on nationwide register data. The secondary aim was to determine the change in the absolute incidence and implant survival of multiply revised knee arthroplasties Methods: We performed a retrospective observational study of primary knee arthroplasties using several nationwide Danish registers. All primary knee arthroplasties performed in Denmark from 1998 to 2021 were identified. From these primary arthroplasties, revision procedures were identified. Kaplan-Meier plots were used in survival analysis to estimate the likelihood of implant survival. RESULTS: 161,384 primary knee arthroplasties and their revisions performed between 1998 and 2021 were identified; of 13,786 (8.5%) revisions there were 10,638 1st revisions, 2,148 2nd revisions, 624 3rd revisions, 223 4th revisions, and 153 procedures that had been revised more than 4 times. The 10-year revision-free survival of primary arthroplasties was 92.3% (95% confidence interval [CI] 92.2-92.5). First-time revisions had a 10-year revision-free survival of 75.9% (CI 74.9-76.9). The 10-year survival of second- and third-time revisions was 65.1% (CI 62.6-67.6) and 57.8% (CI 53.4-62.5), respectively. The 10-year implant survival probabilities of primary knee arthroplasties were 91.4% in 1998-2009 and 93.3% in 2010-2021 (difference 2.2%). The 10-year implant survival probabilities of 1st revisions were 77% in 1998-2009 and 75% in 2010-2021 (difference -2.4%). CONCLUSION: We found that 0.3% of all primary knee arthroplasties resulted in 3 or more revisions. The implant survival decreased for each consecutive revision, with almost half of the 3rd revisions being re-revised within 10 years. The 10-survival of the primary implant was higher in 2010-2021, and the 10-year survival of the 1st revision was higher in 1998-2009.

Early monitoring of inlay wear after total knee arthroplasty on plain radiographs using model-based wear measurement.

Wear of the ultra-high molecular-weight polyethylene (UHMWPE) component in total knee arthroplasty contributes to implant failure. It is often detected late, when patients experience pain or instability. Early monitoring could enable timely intervention, preventing implant failure and joint degeneration. This study investigates the accuracy and precision (repeatability) of model-based wear measurement (MBWM), a novel technique that can estimate inlay thickness and wear radiographically. Six inlays were milled from non-crosslinked UHMWPE and imaged via X-ray in anteroposterior view at flexion angles 0°, 30°, and 60° on a phantom knee model. MBWM measurements were compared with reference values from a coordinate measurement machine. Three inlays were subjected to accelerated wear generation and similarly evaluated. MBWM estimated inlay thickness with medial and lateral accuracies of 0.13 ± 0.09 and 0.14 ± 0.09 mm, respectively, and linear wear with an accuracy of 0.07 ± 0.06 mm. Thickness measurements revealed significant lateral differences at 0° and 30° (0.22 ± 0.08 mm vs. 0.06 ± 0.06 mm, respectively; t-test, p = 0.0002). Precision was high, with average medial and lateral differences of - 0.01 ± 0.04 mm between double experiments. MBWM using plain radiographs presents a practical and promising approach for the clinical detection of implant wear.

Polyethylene liner dissociation in total hip arthroplasty: a retrospective case-control study on a single implant design.

BACKGROUND: Modular acetabular components for total hip arthroplasty (THA) provide intraoperative flexibility; however, polyethylene liner dissociation may occur. This study aimed to examine the incidence and causes of liner dissociation associated with a specific acetabular component design at a single centre. MATERIALS AND METHODS: A retrospective analysis of 7027 patients who underwent primary THA was performed to identify isolated liner dislocations. Patient demographics, clinical presentations, surgical and implant details, and both radiographic and computed tomography (CT) findings were analysed. Patients with liner dislocation were matched to a control group via 2:1 propensity score matching, and a logistic regression analysis was employed to identify associated risk factors. RESULTS: A total of 32 patients (0.45%) experienced liner dislocation at a mean 71.47 ± 60.10 months post surgery. Significant factors contributing to dislocations included the use of a conventional compared with a highly crosslinked polyethylene component (p = 0.049) and screw fixation (p = 0.028). Radiographic and CT analysis highlighted the importance of proper component orientation, revealing that patients experiencing dislocations demonstrated significantly lower acetabular cup anteversion angles (p = 0.001) compared with the control group. Impingement and malposition, identified in 41% and 47% of the cases, respectively, further underscored the multifactorial nature of dislocation risks. CONCLUSIONS: While the overall rate of polyethylene liner dislocation was low, the findings of this study highlight the importance of appropriate cup placement to decrease the risk of dissociation. It further substantiates the influence of impingement and malposition in liner displacement, with increased mechanical stress exerted on the locking mechanism under adverse conditions and the potential risk increase due to screw placement.

Dual Mobility Versus Fixed Bearing Implants in Primary Total Hip Arthroplasty in Patients Under 55 Years of Age.

INTRODUCTION: Prosthetic dislocation after total hip arthroplasty (THA) is one of the most common causes of revision THA. Dual-mobility (DM) bearings were introduced to mitigate complications; however, there is minimal data on their performance in younger patients. This study compared results of patients who were under 55 years of age undergoing primary THA with DM or fixed-bearing (FB) implants. METHODS: A retrospective review of patients younger than 55 years who underwent primary THA with at least 2 years of follow-up between June 2011 and August 2019 was performed. Patients were stratified into two cohorts based on the implant they received (DM vs. FB). Primary outcomes were 90-day all-cause readmission, dislocation, all-cause revision, 90-day readmission and revision due to dislocation, and implant component survivorship. Demographic differences were assessed using chi-squared and independent samples t-tests. Outcomes were compared using multivariate linear and logistic regressions to control for confounding variables. RESULTS: A total of 803 patients were included (DM = 73, FB = 730). The DM and FB cohorts had similar rates of 90- day all-cause readmission (6.8% vs. 3.2%; p = 0.243) and 90-day readmission due to dislocation (4.1% vs. 0.8%; p = 0.653). At a mean follow-up of 4.42 ± 1.91 years, dislocation (4.1% vs. 1.1%; p = 0.723) and all-cause revision (5.5% vs. 4.9%; p = 0.497) rates between the DM and FB cohorts were similar. Kaplan Meier analysis yielded no significant differences in survivorship between groups for all-cause revision (95.1% vs. 94.5%; p = 0.923), revision due to dislocation (100% vs. 98.9%; p = 0.370), and acetabular component revision (97.3% vs. 98.6%; p = 0.418). CONCLUSION: Dual mobility implants demonstrate similar dislocation rates and implant survivorship compared to FB in patients less than 55 years of age. Larger trials with long-term follow-up may be required to further elucidate the effects of DM bearings compared to FB inserts in younger patients undergoing primary THA.

[In-Vitro Analysis of Polyethylene Liner Wear Performance at 3 and 5 Million Cycles].

Objective: The purpose of this study is to compare the wear properties of UHMWPE acetabular liners after undergoing 3 million (3 Mc) and 5 million (5 Mc) cycles of in-vitro wear testing. The results will serve as a reference for the design of in-vitro testing for hip prostheses and as a control for clinical revision removals. Methods: Wear tests were conducted on three different sizes of acetabular liners (28 mm, 32 mm, and 36 mm internal diameters) using a hip simulator to determine the amount of wear after 3 and 5 million cycles. The analysis included the number, size, and shape of abrasive particles. Results: After 3 and 5 million cycles of wear, the amount of wear on the acetabular liner increased as the inner diameter increased. The abrasive particles had an average equivalent circular area diameter (ECD) of 0.27 µm and 0.29 µm, and 94.4% and 90.1% of the aspect ratio (AR) less than 4. Conclusion: The amount of wear on the acetabular liner after 3 Mc wear can indicate the wear performance of the product. The number of particles increased and the percentage of fibrous particles was higher after 5 Mc wear compared to 3 Mc wear.

VDR Gene Polymorphisms (BsmI, FokI, TaqI, ApaI) in Total Hip Arthroplasty Outcome Patients.

A total hip arthroplasty (THA) can improve quality of life, but loosening of the hip prosthesis is a complex problem in which vitamin D may also play a role. The Vitamin D Receptor (VDR) is involved in the response of cells to the action of vitamin D, and its genetic variability raises the question of whether individual differences could influence the risk of prosthesis loosening. The aim of this study was to investigate the relationship between VDR single nucleotide polymorphisms (SNPs) (ApaI, BsmI, FokI and TaqI) and the serum VDR and 25(OH)D levels in three groups of patients: (1) arthroscopy patients after THA without loosening of the prosthesis (CA-Control Arthroplasty), (2) patients after THA with loosened hip prostheses (L-Loosening) and (3) the control group (C-Control). Our results suggest that the genotypes tt of TaqI, BB of BsmI, and FF of FokI may influence the VDR effect in patients with loosened protheses. Our results showed that the ACAC haplotype (AtBF) was over two times more frequent in the L group than in CA + C: OR =2.35 [95% CI 1.44-3.83; p = 0.001]. There was no significant correlation between the VDR and serum 25(OH)D levels, but there were differences between studied groups.

Comparison of Outcomes with the Use of Different Heat-Activated Crimping Prostheses in Stapedotomy.

OBJECTIVE: To determine differences in failure rate and hearing outcomes of a completely encircling heat-activated crimping prosthesis (SMart 360°) compared to partially encircling prosthesis (SMart). STUDY DESIGN: Retrospective chart review. SETTING: Private neurotology tertiary referral center. PATIENTS: Patients who underwent stapedotomies performed by the senior authors from 2008 to 2019 using the SMart prosthesis and SMart 360° prothesis. INTERVENTIONS: Stapedotomy operations with placement of a SMart or SMart 360° prosthesis. MAIN OUTCOME MEASURES: Incidence of early failure requiring revision surgery. Differences in preoperative air-bone gap (ABG) compared to postoperative ABG at 3 months, 1 year, and 2 years after surgery. RESULTS: A total of 228 stapedotomies were performed (SMart n = 48 and SMart 360° n = 180). Mean preoperative ABG for SMart and SMart 360° were 26.15 and 29 dB, respectively. The mean difference in ABG for the SMart at 3 months, 1 year, and 2 years were 17, 18, and 11 dB, respectively. The mean difference in ABG for the SMart 360° at 3 months, 1 year, and 2 years were 20, 20, and 19 dB. ABG differences at 3 months (p = 0.10) and 1 year (p = 0.36) were not statistically different. The failure rate for the SMart prosthesis was 12.5% and for the SMart 360° 2.2% (p = 0.002). CONCLUSIONS: There were no statistically significant differences in ABG changes for SMart compared to SMart 360°. The Smart 360 corrects the problem with early failure seen with the Smart prosthesis. PROFESSIONAL PRACTICE GAP AND EDUCATIONAL NEED: Determination of most efficacious stapes prosthesis. LEARNING OBJECTIVE: Which stapes prosthesis produces better hearing results with fewer failures. DESIRED RESULT: To disseminate information necessary to choose the best stapes prosthesis for patients. LEVEL OF EVIDENCE: Level III. INDICATE IRB OR IACUC: 2022-029-agh.

Periprosthetic Femoral Fractures-Beyond B2.

The proliferation of hip arthroplasty has seen concomitant increases in periprosthetic femoral fractures (PFFs). The most common pattern involves fracture at the level of a loose prosthesis (B2). B2 PFFs have a unique mechanopathogenesis linked to the tendency of polished taper-slip cemented stems to subside in the cement. Such stems carry a much higher PFF risk than other cemented designs. Mega-data, consistent across national registries, suggest that increasing application of the taper-slip principle has resulted in the emergence of highly polished, very low friction cemented prostheses. These have the propensity to migrate within the cement, increasing B2 PFF risk. This would explain the strong association between cobalt-chromium stems and PFF. Is PFF the mode of failure of polished taper-slip stems rather than aseptic loosening? Established wisdom teaches that B2 PFFs should be managed with revision surgery. There is a large body of new evidence that, in certain instances, fixation results in outcomes at least equivalent to revision arthroplasty, with shorter surgical time, decreased transfusion requirements, and lower dislocation risk. This is so in B2 PFFs around cemented polished taper-slip stems with an intact bone-cement interface. We outline advances in understanding of B2 PFF with special reference to mechanopathogenesis and indications for fixation.

Elevated Titanium Levels After Revision Total Hip Caused by Previously Unreported Mechanism.

INTRODUCTION: Metallosis from total hip arthroplasty is usually due to trunnionosis and is associated with elevated serum cobalt and chromium levels. Titanium levels usually remain normal. METHODS: Here, we report two rare cases of elevated titanium levels, both with the same mechanism, which is a previously unreported cause of titanium metallosis. RESULTS: In these cases, contact between cables and the titanium stem were the source. DISCUSSION: Reports of isolated high titanium levels associated with total hip arthroplasty are rare. These cases illustrate a new mechanism from which this situation may arise.

Isolated Polyethylene Insert Exchange for Instability after Total Knee Arthroplasty: Comparable Survival Rates and Range of Motion and Improved Clinical Scores Regardless of Hyperextension.

Background: Isolated polyethylene insert exchange (IPIE) has not been established as a treatment option for hyperextension instability after primary total knee arthroplasty (TKA). The purpose of the study was to evaluate the survival rate and clinical outcomes of IPIE for the treatment of instability with or without hyperextension after TKA. Methods: This study retrospectively reviewed 46 patients who underwent IPIE for symptomatic prosthetic knee instability by dividing them into 2 groups based on the presence of hyperextension (without for group I and with for group IH). Patient demographics, clinical scores, radiographic data, range of motion (ROM), and surgical information were collected. Clinical failure was defined as a subsequent surgery following IPIE for any reason. The survival rate of IPIE and differences in demographics, clinical scores, and ROM were compared. Results: There were 46 patients (91% were women) with an average age of 70.1 years and a mean follow-up of 44.8 months. The average time between primary TKA and IPIE surgery was 6.5 ± 4.2 years, and during IPIE, 2 out of the 8 cruciate-retaining inserts were converted to "deep-dish" ultracongruent inserts while the insert thickness increased from 11.9 ± 1.8 mm to 17.1 ± 3.1 mm. After IPIE surgery, a significantly thicker tibial insert was used in the group with hyperextension (15.39 ± 2.4 mm for group I, 18.3 ± 2.9 mm for group IH; p < 0.001 by independent t-test), and no significant differences were observed in the ROM and clinical scores before and after IPIE between the 2 groups. The overall survival rate for IPIE was 83% at 5 years and 57% at 10 years, and there were no statistically significant differences between the groups using the Cox proportional hazards regression model. Conclusions: IPIE demonstrated an overall survival rate of 83% at 5 years with no difference in the recurrence of instability regardless of hyperextension. This study highlighted the effectiveness of using thicker inserts to resolve instability without significant differences in the ROM or clinical scores between the groups, suggesting its potential as a decision-making reference for surgeons.

Comparing the lifespan of virgin artificial urinary sphincters in radiated patients: transcorporal vs. standard placement.

PURPOSE: To compare the lifespan of first transcorporal cuff (TC) placement of an artificial urinary sphincter (AUS) versus standard placement (SP) in patients with prior radiotherapy (RT) for prostate cancer (PCa). METHODS: We reviewed first (virgin) AUS placements from two high-volume care centers between 1/2011 and 1/2021, including PCa patients with RT history. AUS lifespan was assessed via the hazard ratio of device explantation and/or revision within a ten-year timeframe for the TC vs. SP approaches. Chi-square, Fisher's exact, and t-tests compared clinicodemographic variables. Kaplan-Meier curve compared TC and SP lifespan. RESULTS: 85/314 men with AUS met inclusion criteria, with 38.8% (33/85) in the TC group and 61.2% (52/85) in the SP group. Median ages were 69.8 (IQR = 65.2-73.6) and 67.1 (61.6-72.9), respectively, p = 0.17. Over a median follow up of 51.9 (15.8-86.1) and 80.4 (28.1-128.3) months for the TC and SP, overall, 12 (36.4%) TC devices were removed (four [12.1%] due to mechanical failures; eight [24.2%] erosions, and two [6.1%] infections) vs. 29 (55.8%) in the SP group (14 [26.9%] mechanical failures; 11 [21.1%] erosions, and five [9.6%] infections). No statistically significant differences were observed between the two approaches, with HR = 0.717, 95% CI 0.37-1.44, p = 0.35. The calculated device survival probabilities for the TC vs. SP at one, five, and 10 years were 78.8% vs. 76.9%, 69.3% vs. 58.7%, and 62.1% vs. 46.7%, respectively. CONCLUSIONS: TC cuff insertion for the first AUS implantation in pre-radiated patients showed to be comparable to SP when it comes to device survival, with comparable complication rates. Current guidance for approach selection is primarily based on patient selection and surgeon preference.

[Medium- and long-term effectiveness of hip revision with SL-PLUS MIA stem in patients with Paprosky type â - â ¢ femoral bone defect].

Objective: To investigate the medium- and long-term effectiveness of hip revision with SL-PLUS MIA stem in patients with Paprosky typeⅠ-Ⅲ femoral bone defect. Methods: Between June 2012 and December 2018, 44 patients with Paprosky typeⅠ-Ⅲ femoral bone defect received hip revision using SL-PLUS MIA stem. There were 28 males and 16 females, with an average age of 57.7 years (range, 31-76 years). Indications for revision comprised aseptic loosening (27 cases) and periprosthetic joint infection (17 cases). The Harris hip scores were 54 (48, 60) and 43 (37, 52) in patients with aseptic loosening and periprosthetic joint infection, respectively. The preoperative femoral bone defects were identified as Paprosky type Ⅰ in 32 cases, type Ⅱ in 9 cases, type ⅢA in 2 cases, and type ⅢB in 1 case. Operation time and intraoperative blood transfusion volume were recorded. During follow-up after operation, the hip joint function were evaluated by Harris hip score and X-ray films, the femoral stem survival was analyzed, and the surgical related complications were recorded. Results: The operation time of infected patients was 95-215 minutes, with an average of 125.0 minutes. The intraoperative blood transfusion volume was 400-1 800 mL, with an average of 790.0 mL. The operation time of patients with aseptic loosening was 70-200 minutes, with an average of 121.0 minutes. The intraoperative blood transfusion volume was 400-1 400 mL, with an average of 721.7 mL. All patients were followed up 5.3-10.0 years (mean, 7.4 years). At last follow-up, the Harris hip scores were 88 (85, 90) and 85 (80, 88) in patients with aseptic loosening and periprosthetic joint infection, respectively, both of which were significantly higher than those before operation ( P<0.05). Radiological examination results showed that the distal end of the newly implanted femoral stem did not cross the distal end of the original prosthesis in 25 cases, and all femoral stems obtained bone fixation. Two cases experienced femoral stem subsidence and 1 case had a translucent line on the lateral side of the proximal femoral stem. When aseptic loosening was defined as the end event, the 10-year survival rate of the SL-PLUS MIA stem was 100%. When treatment failure due to any reason was defined as the end event, the survival time of the prosthesis was (111.70±3.66) months, and the 7-year survival rate was 95.5%. The 7-year survival rates were 94.1% and 96.3% in patients with aseptic loosening and periprosthetic joint infection, respectively. The incidence of postoperative complications was 9.1% (4/44), among which the prosthesis related complications were 4.5% (2/44), 1 case of dislocation and 1 case of infection recurrence. Conclusion: Hip revision with SL-PLUS MIA stem has the advantages of simple operation and few postoperative complications in the patients with Paprosky type Ⅰ-Ⅲ femoral bone defect, and the medium- and long-term effectiveness is reliable.

High revision rate of metal-backed glenoid component and impact on the overall revision rate of stemless total shoulder arthroplasty: a cohort study from the Danish Shoulder Arthroplasty Registry.

BACKGROUND AND PURPOSE: There is controversy regarding the results of stemmed and stemless total shoulder arthroplasty (TSA) used for osteoarthritis. Therefore, we aimed to compare revision rates of stemmed and stemless TSA and to examine the impact of metal-backed glenoid components. METHODS: We included all patients reported to the Danish Shoulder Arthroplasty Register from January 1, 2012 to December 31, 2022 with an anatomical TSA used for osteoarthritis. Primary outcome was revision (removal or exchange of components) for any reason. RESULTS: 3,338 arthroplasties were included. The hazard ratio for revision of stemless TSA adjusted for age and sex was 1.83 (95% confidence interval [CI] 1.21-2.78) with stemmed TSA as reference. When excluding all arthroplasties with a metal-backed glenoid component, the adjusted hazard ratio for revision of stemless TSA was 1.37 (CI 0.85-2.20). For the Eclipse stemless TSA system, the adjusted hazard ratio for revision of a metal-backed glenoid component was 8.75 (CI 2.40-31.9) with stemless Eclipse with an all-polyethylene glenoid component as reference. CONCLUSION:  We showed that the risk of revision of stemless TSAs was increased and that it was related to their combination with metal-backed glenoid components.

Effect of body mass index on 30-day complication rate and implant survival rate after simultaneous bilateral unicompartmental knee arthroplasty: a multicentre retrospective study.

OBJECTIVE: The practice of simultaneous bilateral unicompartmental knee arthroplasty (SBUKA) remains a topic of debate, particularly in patients with obesity. Thus, the purpose of this study was to assess the impact of body mass index (BMI) on the 30-day complication rate and the survival rate of the implant following SBUKA. METHODS: We retrospectively examined the clinical records of 245 patients (490 knees) who underwent SBUKA at the Affiliated Hospital of Qingdao University and the Third Hospital of Hebei Medical University between January 2010 and December 2020. Patients were categorised based on their BMI at the time of surgery into four groups: normal weight (BMI 18.5 to 22.9 kg/m2), overweight (BMI 23.0 to 24.9 kg/m2), obese (BMI 25.0 to 29.9 kg/m2), and severely obese (BMI ≥30 kg/m2). Variables such as length of hospital stay, duration of surgery, and costs of hospitalisation were compared across all groups. Additionally, we recorded the 30-day postoperative complication rate and the time from surgery to any required revision. The Kaplan-Meier survival analysis was employed to evaluate and compare the implant survival rates. RESULTS: The follow-up period for the 245 patients ranged from 39 to 114 months, with an average of 77.05±18.71 months. The incidence of complications within 30 days post-surgery did not significantly differ across the groups (χ2 = 1.102, p = 0.777). The implant survival rates from the lowest to the highest BMI groups were 97.14%, 93.9%, 94.44%, and 96.43%, respectively. Both the rate of implant revision (χ2 =1.612, p = 0.657) and the survival curves of the implants (p = 0.639) showed no statistically significant differences among the groups. CONCLUSIONS: BMI did not influence the 30-day complication rate nor the survival rate of implants following SBUKA, suggesting that SBUKA should not be contraindicated based on BMI alone.

Long term follow up of 257 consecutive cementless Oxford medial compartment knee arthroplasties at a non-designer centre.

AIMS: This study aimed to review the survivorship, indication for revision and patient reported outcomes for 257 consecutive Oxford cementless unicompartmental knee arthroplasties (OUKA's) in 238 patients at 12-14 years post-operatively. METHODS: Patients underwent surgery between April 2008 and October 2010 by two non-design surgeons including their learning curve. The 5-year clinical and radiological outcomes have already been reported. Oxford knee scores (OKS) were recorded at 1, 5 and 12-14 years with delayed review a result of the COVID-19 pandemic. Revision indication and imaging were reviewed. RESULTS: Revision was required in 28 OUKA's (10.9%) with a 10-year cumulative survival of 93.0%, reducing to 78.8% at 14 years. 59 patients had died prior to this review and 24 were not contactable. Those not contactable had electronic records reviewed to ensure they did not have a revision elsewhere. Half of the revisions were for progression of lateral compartment arthritis (14/28). Four of 6 cases with a full revision for polyethylene wear may have benefited from a bearing exchange instead. OKSs in non-revised patients were good (median score 38, IQR 30-44) with no significant deterioration noted from 5 to 12-14 years. CONCLUSIONS: Cementless OUKA in this series had a long-term survival rate comparable to other OUKA's outside of the designer centre. OKSs remain good for those patients not revised. Progression of lateral compartment arthritis was the primary reason for revision with no revisions for component loosening or bearing spinout. Ideally UKA patients who experience problems should be under the care of revisions surgeons who perform UKA. Improving patient selection and understanding of the pathophysiology of lateral disease progression, remain crucial to improve the long-term survivorship of OUKA.

Midterm results for revision total knee arthroplasty for component malrotation.

INTRODUCTION: Accurate positioning of components in total knee arthroplasty (TKA) is essential to a satisfactory outcome. Significant malrotation may lead to chronic pain, stiffness, and dysfunction. This study aims to quantify improvements in functional outcomes following revision surgery for malrotation of either one or both components in TKA versus revision for aseptic loosening. METHODS: This was a retrospective review of TKAs that matched and compared the two-year functional outcomes of the malrotation group to a functionally similar aseptic loosening group. Functional outcomes were compared between groups using Short Form (SF-12), Western Ontario and McMaster University Osteoarthritis Index (WOMAC), and Knee Society Functional Score (KSFS). Student t-tests and chi-squared or Fisher's tests were used for statistical analysis. RESULTS: Of the patients revised, 24 had malrotation and 57 had aseptic loosening. A total of 16 femoral and 17 tibial components were revised for malrotation. All 16 femoral components were internally malrotated (mean -4.8 ± 4.1 degrees; range, -0.5 to -16.6). Of the tibial components, 15 were internally malrotated, (mean -9.5 ± 6.6 degrees; range, -2.2 to -23.5) and 2 were externally malrotated (mean 4.6 ± 2.1 degrees; range, 3.1 to 6.0). All functional outcome measures significantly improved comparably within both groups preoperatively to 24 months postoperatively. At 24 months, functional outcome measures were comparable between the groups and WOMAC function scores were significantly higher in the malrotation group. CONCLUSION: Revision TKA for malrotation can yield clinically and statistically significant functional improvements, similar in magnitude to those seen following revision TKA for aseptic loosening. LEVEL OF EVIDENCE: Level III.