Mobile-bearing (MB) total knee replacement (TKR) was introduced to reduce the risk of aseptic loosening and wear of polyethylene inserts. However, no consistent clinical advantages of mobile- over fixed-bearing (FB) TKR have been found. In this study we evaluated whether mobile bearings have an advantage over fixed bearings with regard to revision rates and clinical outcome scores. Furthermore, we determined which modifying variables affected the outcome. A systematic search of the literature was conducted to collect clinical trials comparing MB and FB in primary TKR. The primary outcomes were revision rates for any reason, aseptic loosening and wear. Secondary outcomes included range of movement, Knee Society score (KSS), Oxford knee score (OKS), Short-Form 12 (SF-12) score and radiological parameters. Meta-regression techniques were used to explore factors modifying the observed effect. . Our search yielded 1827 publications, of which 41 studies met our inclusion criteria, comprising over 6000 TKRs. Meta-analyses showed no clinically relevant differences in terms of revision rates, clinical outcome scores or patient-reported outcome measures between MB and FB TKRs. It appears that theoretical assumptions of superiority of MB over FB TKR are not borne out in clinical practice. Cite this article: Bone Joint J 2013;95-B:1209–16

Introduction. Comparative studies examining Fixed-Bearing (FB) and Mobile-Bearing (MB) Total Ankle Replacement (TAR) designs have demonstrated similar results and successful long-term outcomes for both. To date there has been no study directly comparing FB and MB designs of the same prosthesis. We present the first prospective randomised trial comparing patient satisfaction, functional outcomes and radiographic results of the Salto Talaris Fixed-Bearing and the Salto Mobile-Bearing Total Ankle Replacement in the treatment of end-stage ankle arthritis. Methods. A total of 108 adult patients with end-stage ankle arthritis were enrolled in the study between November 2014 and October 2021 with similar demographic comparison. Prospective patient-reported outcomes and standardised weightbearing ankle radiographs were performed preoperatively, at 6 weeks, 6 months and 12 months post-operatively, followed by yearly intervals. All surgeries were performed by a single non-design orthopaedic foot and ankle specialist with experience in over 200 Salto and Salto Talaris TAR prior to the study. Radiographs were examined independently by two clinicians. Complete patient data and radiographs were available for 103 patients with an average follow up of 2 years. Results. Both groups demonstrated statistically significant improvement from preoperative evaluation to most recent follow up with no statistically significant difference between the two groups in all outcome measures. Radiographic incidence of subchondral cyst formation was 8.9% and 38.2% for FB and MB, respectively. Talar subsidence occurred in 2.2% and 5.5% of FB and MB, respectively. Discussion. Our study demonstrates a higher than previously reported rate of cyst formation in the MB TAR and comparatively higher talar subsidence in the MB TAR vs FB however this did not correlate with clinical outcome measures which were favourable for both groups. Conclusion. Fixed-Bearing and Mobile-Bearing Total Ankle Replacement demonstrate comparable favourable

Aims. The Vantage Total Ankle System is a fourth-generation low-profile fixed-bearing implant that has been available since 2016. We aimed to describe our early experience with this implant. Methods. This is a single-centre retrospective review of patients who underwent primary total ankle arthroplasty (TAA) with a Vantage implant between November 2017 and February 2020, with a minimum of two years’ follow-up. Four surgeons contributed patients. The primary outcome was reoperation and revision rate of the Vantage implant at two years. Secondary outcomes included radiological alignment, peri-implant complications, and pre- and postoperative patient-reported outcomes. Results. There were 168 patients (171 ankles) included with a mean follow-up of 2.81 years (2 to 4.6) and mean age of 63.0 years (SD 9.4). Of the ten ankles with implant failure (5.8%), six had loosening of the tibial component. In the remaining four failed implants, one was due to periprosthetic joint infection (PJI), one was due to loosening of the talar component, and two were due to loosening of both the tibial and talar components. Seven patients underwent reoperation: irrigation and debridement for superficial infection (n = 4); bone grafting for cysts (n = 2); and open reduction internal fixation (n = 1). Asymptomatic peri-implant lucency/subsidence occurred in 20.1% of ankles, with the majority involving the tibial component (n = 25). There were statistically significant improvements in PROMs in all domains. Conclusion. Short-term results of this implant demonstrate early survival comparable to the reported survivorship of similar low-profile, non-stemmed implants. Radiological lucency occurred more commonly at the tibial component, and revisions occurred primarily due to loosening of the tibial component. Further research is needed to evaluate longer-term survivorship. Cite this article: Bone Joint J 2023;105-B(10):1099–1107

Objectives. Elevated proximal tibial bone strain may cause unexplained pain, an important cause of unicompartmental knee arthroplasty (UKA) revision. This study investigates the effect of tibial component alignment in metal-backed (MB) and all-polyethylene (AP) fixed-bearing medial UKAs on bone strain, using an experimentally validated finite element model (FEM). Methods. A previously experimentally validated FEM of a composite tibia implanted with a cemented fixed-bearing UKA (MB and AP) was used. Standard alignment (medial proximal tibial angle 90°, 6° posterior slope), coronal malalignment (3°, 5°, 10° varus; 3°, 5° valgus), and sagittal malalignment (0°, 3°, 6°, 9°, 12°) were analyzed. The primary outcome measure was the volume of compressively overstrained cancellous bone (VOCB) < -3000 µε. The secondary outcome measure was maximum von Mises stress in cortical bone (MSCB) over a medial region of interest. Results. Varus malalignment decreased VOCB but increased MSCB in both implants, more so in the AP implant. Varus malalignment of 10° reduced the VOCB by 10% and 3% in AP and MB implants but increased the MSCB by 14% and 13%, respectively. Valgus malalignment of 5° increased the VOCB by 8% and 4% in AP and MB implants, with reductions in MSCB of 7% and 10%, respectively. Sagittal malalignment displayed negligible effects. Well-aligned AP implants displayed greater VOCB than malaligned MB implants. Conclusion. All-polyethylene implants are more sensitive to coronal plane malalignments than MB implants are; varus malalignment reduced cancellous bone strain but increased anteromedial cortical bone stress. Sagittal plane malalignment has a negligible effect on bone strain. Cite this article: I. Danese, P. Pankaj, C. E. H. Scott. The effect of malalignment on proximal tibial strain in fixed-bearing unicompartmental knee arthroplasty: A comparison between metal-backed and all-polyethylene components using a validated finite element model. Bone Joint Res 2019;8:55–64. DOI: 10.1302/2046-3758.82.BJR-2018-0186.R2

Objectives. Our study aimed to examine if a mobile-bearing total knee replacement (TKR) offered an advantage over fixed-bearing designs with respect to rates of secondary resurfacing of the patella in knees in which it was initially left unresurfaced. Methods. We examined the 11-year report of the New Zealand Joint Registry and identified all primary TKR designs that had been implanted in > 500 knees without primary resurfacing of the patella. We examined how many of these were mobile-bearing, fixed-bearing cruciate-retaining and fixed-bearing posterior-stabilised designs. We assessed the rates of secondary resurfacing of the patella for each group and constructed Kaplan-Meier survival curves. Results. Our study showed a significantly higher rate of revision for secondary resurfacing of the patella in the fixed-bearing posterior-stabilised TKR designs compared with either fixed-bearing cruciate-retaining or mobile-bearing designs (p = 0.001 and p = 0.036, respectively). Conclusions. This New Zealand Registry study shows that during the last 11 years, revision procedures to resurface an unresurfaced patella in primary TKR occurred at a higher rate in fixed-bearing posterior-stabilised designs

Components from 73 failed knee replacements (TKRs) consisting of rotating-platform, mobile-bearing and fixed-bearing implants were examined to assess the patterns of wear. The patterns were divided into low-grade (burnishing, abrasion and cold flow) and high-grade (scratching, pitting/metal embedding and delamination) to assess the severity of the wear of polyethylene. The rotating-platform group had a higher incidence of low-grade wear on the upper surface compared with the fixed-bearing group. By contrast, high-grade wear comprising scratching, pitting and third-body embedding was seen on the lower surface. Linear regression analysis showed a significant correlation of the wear scores between the upper and lower surfaces of the tibial insert (R. 2. = 0.29, p = 0.04) for the rotating-platform group, but no significant correlation was found for the fixed-bearing counterpart. This suggests that high-grade wear patterns on the upper surface are reduced with the rotating-platform design. However, the incidence of burnishing, pitting/third-body embedding and scratching wear patterns on the lower surface was higher compared with that in the fixed-bearing knee

Abstract. Objectives. Hip instability following total hip arthroplasty in treatment of intracapsular neck of femur fractures is reported at 8–11%. Utilising the principle of a small articulation to minimize the problems of wear coupled with a large articulation, dual-mobility total hip arthroplasty prostheses stabilise the hip further than conventional fixed-bearing designs. The aim of this study is to compare the rate of dislocation and complication between standard fixed-bearing and dual-mobility prostheses for the treatment of intracapsular neck of femur fractures. Methods. A four-year retrospective review in a large district general hospital was completed. All cases of intracapsular neck of femur fractures treated with total hip arthroplasty were identified through the theatre logbooks. Patient's operative and clinical notes were retrospectively reviewed to collect data. Results. A total of 91 patients underwent total hip arthroplasty for intracapsular neck of femur fracture in the four-year period. 61.5% were dual-mobility design versus 28.5% had fixed-bearing implants. There were no statistical differences between patient group characteristics. Choice of implant was dependent on surgeon preference. There was a 0.0% dislocation rate in the dual-mobility group versus 8.6% in the fixed-bearing prosthesis group. All dislocations occurred in patients who underwent total hip arthroplasty with 36.0mm fixed-bearing prosthesis via posterior surgical approach. There was no statistical difference in mortality between both groups. Conclusion. There was an increasing trend of towards the use of dual-mobility prosthesis for fractured neck of femur within this department with excellent outcomes. Dual-mobility designs provide reduced dislocation rates in total hip arthroplasty in intracapsular neck of femur fractures compared to standard fixed-bearing designs at this institution. The authors recommend that all orthopaedic staff consider the use of dual-mobility prostheses in suitable patients and ensure trainees are suitably trained in use of dual-mobility designs. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Aims. The optimal bearing surface design for medial unicompartmental knee arthroplasty (UKA) remains controversial. The aim of this study was to compare outcomes of fixed-bearing (FB) and mobile-bearing (MB) UKAs from a single high-volume institution. Methods. Prospectively collected data were reviewed for all primary cemented medial UKAs performed by seven surgeons from January 2006 to December 2022. A total of 2,999 UKAs were identified, including 2,315 FB and 684 MB cases. The primary outcome measure was implant survival. Secondary outcomes included 90-day and cumulative complications, reoperations, component revisions, conversion arthroplasties, range of motion, and patient-reported outcome measures. Overall mean age at surgery was 65.7 years (32.9 to 94.3), 53.1% (1,593/2,999) of UKAs were implanted in female patients, and demographics between groups were similar (p > 0.05). The mean follow-up for all UKAs was 3.7 years (0.0 to 15.6). Results. Using revision for any reason as an endpoint, five-year survival for FB UKAs was 97.2% (95% CI 96.4 to 98.1) compared to 96.0% for MB (95% CI 94.1 to 97.9; p = 0.008). The FB group experienced fewer component revisions (14/2,315, 0.6% vs 12/684, 1.8%; p < 0.001) and conversion arthroplasties (38/2315, 1.6% vs 24/684, 3.5%; p < 0.001). A greater number of MB UKAs underwent revision due to osteoarthritis progression (FB = 21/2,315, 0.9% vs MB = 16/684, 2.3%; p = 0.003). In the MB group, 12 (1.8%) subjects experienced bearing dislocations which required revision surgery. There were 15 early periprosthetic tibia fractures (0.6%) in the FB group compared to 0 for MB (p = 0.035). Conclusion. In similar patient populations, FB UKAs demonstrated slightly higher survival than a commonly used MB design. Adverse event profiles differed by bearing type, with an increased risk of bearing dislocation and OA progression with MB designs, and early periprosthetic tibia fractures for FB designs. Cite this article: Bone Joint J 2024;106-B(9):916–923

Introduction. The mobile-bearing (MB) total knee arthroplasty (TKA) design was introduced with the aim of reducing polyethylene wear and component loosening seen in the fixed-bearing (FB) design. A recent joint registry study has revealed increased risk for all-cause revision, but not revision for infection, in MB-TKA. We used the New Zealand Joint Registry (NZJR) to compare all-cause revision rates, and revision rates for aseptic loosening of MB-TKA compared with fixed bearing (FB) TKA. Methods. All patients who underwent a primary TKA registered in the NZJR between the 1st January 1999 to 31st December 2021 were identified. Analysis compared MB to FB designs, with sub analysis of implants from a single company. We identified 135,707 primary TKAs, with 104,074 (76.7%) FB-TKAs and 31,633 (23.3%) MB-TKAs recorded. We examined all-cause revision rates, reasons for revision and performed survival analyses. Results. For all-comers, MB-TKA had an all-cause revision rate of 0.43/100-component-years (OCY) compared with 0.42/OCY for FB-TKA (p=0.09). The all-cause revision rate was higher for those age < 65 years (MB TKA 0.60/OCY vs. FB-TKA 0.59/OCY) compared to those > 65 years at time of primary TKA (MB-TKA 0.29/OCY vs. FB-TKA 0.32/OCY), however there was no statistically significant difference between implant design in either age group (p=0.16 and p=0.64; respectively). Similarly, there was no difference in revision rates for aseptic loosening between implant designs. Kaplan-Meier survival analysis demonstrates no statistically significant difference in revision-free survival of implants, with both MB-TKA and FB-TKA demonstrating ∼93% revision free survival at 23 years. Conclusions. Both FB- and MB-TKA demonstrated excellent survivorship, with no significant difference in all-cause revision rates or revision for aseptic loosening between implant designs

Aims. The aim of this study was to assess the influence of obesity on the clinical outcomes and survivorship ten years postoperatively in patients who underwent a fixed-bearing unicompartmental knee arthroplasty (UKA). Patients and Methods. We prospectively followed 184 patients who underwent UKA between 2003 and 2007 for a minimum of ten years. A total of 142 patients with preoperative body mass index (BMI) of < 30 kg/m. 2. were in the control group (32 male, 110 female) and 42 patients with BMI of ≥ 30 kg/m. 2. were in the obese group (five male, 37 female). Pre- and postoperative range of movement (ROM), Knee Society Score (KSS), Oxford Knee Score (OKS), 36-Item Short-Form Health Survey (SF-36), and survivorship were analyzed. Results. Patients in the obese group underwent UKA at a significantly younger mean age (56.5 years (. sd. 6.4)) than those in the control group (62.4 years (. sd. 7.8); p < 0.001). There was no significant difference in preoperative functional scores. However, those in the obese group had a significantly lower ROM (116° (. sd. 15°) vs 123° (. sd. 17°); p = 0.003). Both groups achieved significant improvement in outcome scores regardless of BMI, ten years postoperatively. All patients achieved the minimal clinically important difference (MCID) for OKS and KSS. Both groups also had high rates of satisfaction (96.3% in the control group and 97.5% in the obese group) and the fulfilment of expectations (94.9% in the control group and 95.0% in the obese group). Multiple linear regression showed a clear association between obesity and a lower OKS two years postoperatively and Knee Society Function Score (KSFS) ten years postoperatively. After applying propensity matching, obese patients had a significantly lower KSFS, OKS, and physical component score (PCS) ten years postoperatively. Seven patients underwent revision to total knee arthroplasty (TKA), two in the control group and five in the obese group, resulting in a mean rate of survival at ten years of 98.6% and 88.1%, respectively (p = 0.012). Conclusion. Both groups had significant improvements in functional and quality-of-life scores postoperatively. However, obesity was a significant predictor of poorer improvement in clinical outcome and an increased rate of revision ten years postoperatively

Aims. This study compares the PFC total knee arthroplasty (TKA) system in a prospective randomized control trial (RCT) of the mobile-bearing rotating-platform (RP) TKA against the fixed-bearing (FB) TKA. This is the largest RCT with the longest follow-up where cruciate-retaining PFC total knee arthroplasties are compared in a non-bilateral TKA study. Patients and Methods. A total of 167 patients (190 knees with 23 bilateral cases), were recruited prospectively and randomly assigned, with 91 knees receiving the RP and 99 knees receiving FB. The mean age was 65.5 years (48 to 82), the mean body mass index (BMI) was 29.7 kg/m. 2. (20 to 52) and 73 patients were female. The Knee Society Score (KSS), Knee Society Functional Score (KSFS), Oxford Knee Score (OKS), Western Ontario and McMaster Universities Arthritis Index (WOMAC), and 12-Item Short-Form Health Survey Physical and Mental Component Scores (SF-12 PCS, SF-12 MCS) were gathered and recorded preoperatively, at five-years’ follow-up, and at ten years’ follow-up. Additionally, Knee Injury and Osteoarthritis Outcome Scores (KOOS) were collected at five- and ten-year follow-ups. The prevalence of radiolucent lines (RL) on radiographs and implant survival were recorded at five- and ten-year follow-ups. Results. At the ten-year follow-up, the RP group (n = 39) had a statistically significant superior score in the OKS (p = 0.001), WOMAC (p = 0.023), SF-12 PCS (p = 0.019), KOOS Activities of Daily Living (ADL) (p = 0.010), and KOOS Sport and Recreation (Sport/Rec) (p = 0.006) compared with the FB group (n = 46). The OKS, SF-12 PCS, and KOOS Sport/Rec at ten years had mean scores above the minimal clinically important difference (MCID) threshold. There was no significant difference in prevalence of radiolucency between groups at five-years’ follow-up (p = 0.449), nor at ten-years’ follow-up (p = 0.08). Implant survival rate at 14 years postoperative was 95.2 (95% CI 90.7 to 99.8) and 94.7 (95% CI 86.8 to 100.0) for the RP and FB TKAs, respectively. Conclusion. At ten-year follow-up, the mobile-bearing knee joint arthroplasty had statistically and clinically relevant superior OKS, SF-12 PCS, and KOOS (Sport/Rec) than the fixed-bearing platform. No difference was seen in prevalence of radiolucent lines. There was a greater than 94% implant survival rate for both cohorts at 14 years. Cite this article: Bone Joint J 2018;100-B:1336–44

Background: Although many of the contemporary fixed- and mobile bearing total knee systems have been using extensively world wide, there is limited information available regarding the incidence of osteolysis of the well functioning total knee arthroplasties. We performed this study to evaluate the clinical and radiographic outcomes, the incidence of osteolysis, the revision rates and implant survivorship of the fixed- and mobile-bearing total knee arthroplasties at ten to seventeen years follow-up. Methods: We compared 488 patients (894 knees) who received a fixed-bearing total knee replacement and 445 patients (816 knees) who received a mobile-bearing total knee replacement. There were 187 men and 301 women (mean age, 58.6 years) in the fixed-bearing group and 167 men and 278 women (mean age, 55.7 years) in the mobile-bearing group. The mean follow-up was 12.6 years (range, ten to seventeen years) in the fixed-bearing group and 14.1 years (range, twelve to seventeen years) in the mobile-bearing group. Results: The mean postoperative Knee Society knee and functional scores were 92.9 points and 83.5 points, respectively in the fixed-bearing group. The mean postoperative Knee Society knee and functional scores were 90.7 points and 83.8 points, respectively. Incidence of osteolysis was 1.6% (fourteen of 894 knees) in the fixed-bearing group and it was 2.2% (eighteen of 816 knees) in the mobile-bearing group at the final review. Revision rate was 3.7% (thirty-three of 894 knees) in the fixed-bearing group and it was 2.7% (twenty-two of 816 knees) in the mobile-bearing group. Kaplan-Meier survivorship of the fixed-bearing group was 96.3% (95% confidence interval, 0.87–1.0) at 13 years follow-up and it was 97% (95% confidence interval, 0.90–1.0) of the mobile-bearing group at 14 years follow-up. Conclusions: The present study demonstrates that the clinical and radiographic outcomes, the incidence of osteolysis, the rate of revision and the implant survivorship were similar between the fixed-bearing and mobile-bearing total knee arthroplasties

Background: Durable long-term independent results with the Low Contact Stress rotating-platform (mobile-bearing) and the Insall Burstein-II (fixed-bearing) total knee prostheses have been reported, but no studies describing either the mid-term or long-term results and comparing the two prostheses are available, to our knowledge. Methods: Thirty-two patients who had bilateral arthritis of the knee with similar deformity and preoperative range of motion on both sides and who agreed to have one knee replaced with a mobile-bearing total knee design and the other with a fixed-bearing design were prospectively evaluated. Comparative analysis of both designs was done at a mean follow-up period of six years, minimizing patient, surgeon, and observer-related bias. Clinical and radiographic outcome, survival, and complication rates were compared. Results: Patients with osteoarthritis had better function scores and range of motion compared with patients with rheumatoid arthritis. However, with the numbers available, no benefit of mobile-bearing over fixed-bearing designs could be demonstrated with respect to Knee Society scores, range of flexion, subject preference, or patellofemoral complication rates. Radiographs showed no difference in prosthetic alignment. Two knees with a mobile-bearing prosthesis required a reoperation: one had an early revision because of bearing dislocation and another required conversion to an arthrodesis to treat a deep infection. Conclusions: We found no advantage of the mobile-bearing arthroplasty over the fixed-bearing arthroplasty with regard to the clinical results at mid-term follow-up. The risk of bearing subluxation and dislocation in knees with the mobile-bearing prosthesis is a cause for concern and may necessitate early revision

Introduction. The mobile-bearings were introduced in total knee arthroplasty (TKA) to improve the knee performance by simulating more closely ‘normal’ knee kinematics, and to increase the longevity of TKA by reducing the polyethylene wear and periprosthetic osteolysis. However, the superiority between posterior-stabilized mobile-bearing and fixed-bearing designs still remains controversial. The objective of the present study was to compare the mid-term results of Scorpio + Single Axis system (Stryker Howmedica Osteonics, Allendale, New Jersey) for the mobile-bearing knees and Duracon system (Stryker Howmedica Osteonics, Allendale, New Jersey) for the fixed bearing design with regard to clinical and roentgenographic outcome with special reference to any complications and survivorship. Methods. Prospective, randomized, double-blinded controlled study was carried out on 56 patients undergoing primary, unilateral total knee arthroplasty for osteoarthritis, who were divided into two groups. Group I received mobile-bearing knee prosthesis (29 patients) and Group 2 received fixed-bearing prosthesis (27 patients). The patients were assessed by a physical examination and knee scoring systems preoperatively, at a follow-up of three months, six months, and one year after surgery by independent researcher who was not part of the operating team, and was blinded as to the type of implant inserted. We used the Oxford knee score (OKS) and Knee society score (KSS), with Knee Society Knee Score (KSKS) and Knee Society Functional Score (KSFS) being the subsets. The questionnaire for OKS was printed in our national language, and handed over to the patient at each visit. Results. The Knee Society knee scores, pain scores, functional scores and Oxford knee scores were not statistically different (P > 0.05) between the two groups. Mean postoperative range-of-motion of mobile-bearing knees was significantly greater than that of fixed-bearing knees (127º versus 111º, P = 0.011). 72% of patients could sit cross legged, 48% could sit on the floor, and 17% could squat. Kaplan–Meier survival rate was 100%. No spin-out of mobile bearing was observed. The radiological analysis showed no osteolysis or implant loosening. Conclusion. Mobile-bearing, and fixed-bearing knees demonstrated no statistically significant difference in the Oxford knee score, Knee society score, and radiological outcome with 100% survivorship, at 4 to 6.5 years (mean: 5.5 years) follow up. However, the post-operative range-of-motion of mobile-bearing knees was significantly higher than the fixed-bearing designs (mean, 127° versus 111°; range, 95° to 145° versus 80° to 125°)

Purpose. The mobile-bearing total knee arthroplasty was designed to increase the contact area with the polyethylene bearing, through the functional range of motion, and subsequently decrease the wear rate previously seen in fixed-bearing implants. In the literature there is no clear clinical advantage between the different designs in the short to mid-term follow-up. The purpose of this study was to compare the results between a cruciate retaining mobile-bearing design (SAL II, Sulzer) and two cruciate retaining fixed-bearing designs (AMK, Depuy, and the Genesis II, Smith and Nephew). Method. Ninety patients were randomised to receive either the mobile-bearing or one of the two fixed-bearing designs between 2000 and 2002. Patients were evaluated preoperatively and postoperatively using the WOMAC and the SF-12, both of which are validated scores. One patient was withdrawn due to dementia before three months and eleven patients died. Two patients were revised due to infection (both had received the SAL II). One patient was revised for aseptic loosening and one patient was revised for pain (both had received the Genesis II). Of the 74 patients (77 knees) that remain, they were last seen on average 6.4 years (2–10) after their surgery. Their average age at the surgery was 69.2 years (52–81). Results. There was no statistically significant difference between the change scores (postoperative score minus preoperative score) for each of the outcome measures between the mobile-bearing and the two fixed-bearing designs. Conclusion. In conclusion, after mid-term follow-up there is no clinical difference between a cruciate retaining mobile-bearing design and two cruciate retaining fixed-bearing designs

Before proceeding to longer-term studies, we have studied the early clinical results of a new mobile-bearing total knee prosthesis in comparison with an established fixed-bearing device. Patients requiring bilateral knee replacement consented to have their operations under one anaesthetic using one of each prosthesis. They also agreed to accept the random choice of knee (right or left) and to remain ignorant as to which side had which implant. Outcomes were measured using the American Knee Society Score (AKSS), the Oxford Knee Score (OKS), and determination of the range of movement and pain scores before and at one year after operation. Preoperatively, there was no systematic difference between the right and left knees. One patient died in the perioperative period and one mobile-bearing prosthesis required early revision for dislocation of the meniscal component. At one year the mean AKSS, OKS and pain scores for the new device were slightly better (p < 0.025) than those for the fixed-bearing device. There was no difference in the range of movement. We believe that this is the first controlled, blinded trial to compare early function of a new knee prosthesis with that of a standard implant. It demonstrates a small but significant clinical advantage for the mobile-bearing design

Background. There are case series of debonding of the ATTUNE® tibial component introduced in 2013. We studied the early clinical results of this total knee arthroplasty (TKA) and compared it to other designs at one hospital. Methods. This is a retrospective study of 223 consecutive, non-randomized, cemented fixed-bearing posterior-stabilized ATTUNE® TKAs at one hospital by 5 surgeons from 2013 through 2017. We excluded 4 knees with early infection and 53 with follow-up less than 6 months. Of 166 TKAs reviewed, the mean patient age was 63.8 years, mean BMI 32, and mean follow-up 25 months. We compared this to a “control” cohort of 511 TKAs of other manufacturers performed at the same hospital. The endpoints were revision performed and revision pending. Results. Nineteen (11.5%) ATTUNE® knees have been revised and revision is pending in 12 (7%) knees, at a mean of 30 months. Tibial component loosening was seen in 17 (90%) revised knees. There was no difference between knees revised or revision pending and unrevised knees in patient demographics, cement used (p=0.84), or attending surgeon (p=0.55). In the “control” cohort, there were 13 (2.6%) knees revised (p<0.0001) and revision pending in 8 (1.5%) (p<0.0001), and only 2 had tibial loosening as the reason for revision. Conclusion. This cemented TKA design had an unexpected high early rate of revision. Debonding of the tibial component was the most common reason for failure. Additional longer-term follow-up studies of this component and techniques for implantation are warranted

PCL retaining fixed-bearing TKA is a highly successful operation with the need for more surgery occurring at the rate of approximately 0.4% per year over the first 27 years. The most common cause for revision surgery is related to polyethylene insert failure and accounts for approximately 50% of re-operations. Late metastatic infection is the next most frequent cause followed by patellar problems, late instability and component loosening in decreasing frequency. A myriad of rare miscellaneous problems can also occur

Aims. The purpose of the present study was to examine the long-term fixation of a cemented fixed-bearing polished titanium tibial baseplate (Genesis ll). . Patients and Methods. Patients enrolled in a previous two-year prospective trial (n = 35) were recalled at ten years. Available patients (n = 15) underwent radiostereometric analysis (RSA) imaging in a supine position using a conventional RSA protocol. Migration of the tibial component in all planes was compared between initial and ten-year follow-up. Outcome scores including the Knee Society Score, Western Ontario and McMaster Universities Arthritis Index, 12-item Short Form Health Survey, Forgotten Joint Score, and University of California, Los Angeles Activity Score were recorded. Results. At ten years, the mean migration of the tibial component was less than 0.1 mm and 0.1° in all planes relative to the post-operative RSA exam. Maximum total point movement increased with time (p = 0.002) from 0.23 mm (. sd. 0.18) at six weeks to 0.42 mm (. sd. 0.20) at ten years. Conclusion. The low level of tibial baseplate migration found in the present study correlates to the low rate of revision for this implant as reported in individual studies and in joint replacement registries. Take home message: Overall, the implant was found to be well fixed at ten years, supporting its continued clinical use and the predictive power of RSA for determining long-term fixation of implants. Cite this article: Bone Joint J 2016;98-B:616–21

This study compared the outcome of total knee replacement (TKR) in adult patients with fixed- and mobile-bearing prostheses during the first post-operative year and at five years’ follow-up, using gait parameters as a new objective measure. This double-blind randomised controlled clinical trial included 55 patients with mobile-bearing (n = 26) and fixed-bearing (n = 29) prostheses of the same design, evaluated pre-operatively and post-operatively at six weeks, three months, six months, one year and five years. Each participant undertook two walking trials of 30 m and completed the EuroQol questionnaire, Western Ontario and McMaster Universities osteoarthritis index, Knee Society score, and visual analogue scales for pain and stiffness. Gait analysis was performed using five miniature angular rate sensors mounted on the trunk (sacrum), each thigh and calf. The study population was divided into two groups according to age (≤ 70 years versus > 70 years). Improvements in most gait parameters at five years’ follow-up were greater for fixed-bearing TKRs in older patients (> 70 years), and greater for mobile-bearing TKRs in younger patients (≤ 70 years). These findings should be confirmed by an extended age controlled study, as the ideal choice of prosthesis might depend on the age of the patient at the time of surgery