Introduction

Unicompartmental knee arthroplasty (UKA) is a successful procedure for medial compartment osteoarthritis (OA). Recent studies using the same implant report a revision rate of 2.9%. Other centers have reported revision rates as high as 10.3%. The purpose of this study was to retrospectively review the clinical results of Oxford Phase 3 UKA's performed in the setting of isolated medial compartment OA and to compare our results to the previous mid-term studies. Our secondary goal was to determine reasons for revision and evaluate selected independent predictors of failure.

Source of the study: University of Auckland, Auckland, New Zealand. Unicompartmental knee arthroplasty (UKA) is effective for patients with isolated compartment osteoarthritis, however the procedure has higher revision rates. Long-term survivorship and accurate characterisation of revision reasons are limited by a lack of long-term data and standardised revision definitions. We aimed to identify survivorship, risk factors and revision reasons in a large UKA cohort with up to 20 years follow-up. Patient, implant and revision details were recorded through clinical and radiological review for 2,137 consecutive patients undergoing primary medial UKA across Auckland, Canterbury, Counties Manukau and Waitematā DHB between 2000 and 2017. Revision reasons were determined from review of clinical, laboratory, and radiological records for each patient using a standardised protocol. To ensure complete follow-up data was cross-referenced with the New Zealand Joint Registry to identify patients undergoing subsequent revision outside the hospitals. Implant survival, revision risk and revision reasons were analysed using Cox proportional-hazards and competing risk analyses. Implant survivorship at 15 years was comparable for cemented fixed-bearing (cemFB; 91%) and uncemented mobile-bearing (uncemMB; 91%), but lower for cemented mobile-bearing (cemMB; 80%) implants. There was higher incidence of aseptic loosening with cemented implants (3–4% vs. 0.4% uncemented, p<0.01), osteoarthritis (OA) progression with cemMB implants (9% vs. 3% cemFB/uncemMB; p<0.05) and bearing dislocations with uncemMB implants (3% vs. 2% cemMB, p=0.02). Compared with the oldest patients (≥75 years), there was a nearly two-fold increase in risk for those aged 55–64 (hazard ratio 1.9; confidence interval 1.1-3.3, p=0.03). No association was found with gender, BMI or ASA. Cemented mobile-bearing implants and younger age were linked to lower implant survivorship. These were associated with disease progression and bearing dislocations. The use of cemented fixed-bearing and uncemented mobile-bearing designs have superior comparable long-term survivorship

Permanent patellar subluxation is treated with surgeries such as proximal realignment and distal realignment, however, it is difficult to cure this condition by using any methods. We performed mobile-bearing total knee arthroplasty (TKA) in a case of severe knee osteoarthritis complicated with permanent patellar subluxation since childhood, and obtained good results without performing any additional procedures. The patient was an 82-year-old woman with severe pain in the left knee. During the initial examination, the range of motion of the left knee joint was -10°of extension to 140°of flexion, and the Japanese Orthopaedic Association (JOA) score for knee osteoarthritis was 40 points (maximum score: 100). Preoperative radiographs showed a varus deformity in the left lower extremity with a femorotibial angle (FTA) of 188°, the axial view showed luxation of the patella. We performed TKA using a mobile-bearing implant. Intraoperative findings revealed that the central articular surface of the distal femur had disappeared, and that the patellar articular surface was concave and dome-shaped. The lateral patellofemoral ligament was released; this procedure was identical to that performed in conventional TKA. Postoperative radiographs showed good alignment, with an FTA of 173°. In the axial view, the patella was located in a reduced position at any angle of knee joint flexion. The postoperative range of motion of the left knee joint was 0°of extension to 130°of flexion. The patient was able to walk without the support of a T-shaped cane. There are many surgical treatments for permanent patellar subluxation. The appropriate treatment is selected according to the type and seriousness of the dislocation and the age of the patient. From the findings of the present case, we believe that in a case of knee osteoarthritis complicated with permanent patellar subluxation, surgery performed using a mobile-bearing implant would eliminate the necessity of performing additional proximal realignment and distal realignment

The Zenith. TM. total ankle replacement (Corin, Cirencester) is a mobile-bearing implant based on the Buechal Pappas design. Key features are the simple fully-jigged instrumentation aiming to improve accuracy and reproducibility of implant positioning, cementless calcium phosphate coated surfaces for improved early osseointegration, and titanium nitride-coated bearing surfaces to resist wear. We present early to mid-term survival data for 155 total ankle replacements implanted by three surgeons in our institute. Case records of all patients undergoing Zenith. TM. Total Ankle Replacement by three senior surgeons, including a member of the design team, between 2007 and 2014 were examined. Patients were examined clinically and radiographically annually after the early postoperative period. The primary outcome measure was implant survival. Secondary outcome measures included complication rates, parameters of radiographic alignment, and radiographic evidence of cysts and loosening. One hundred and fifty-five cases were performed for a mixture of primary pathologies, predominantly primary or posttraumatic arthrosis. Mean follow-up was 50 months. Implant survival was 99.0% at 3 years (n=103), 94.0% at 5 years (n=50), and 93.8% at 7 years (n=16). One patient was revised to arthrodesis for aseptic loosening, one arthrodesis was performed for periprosthetic infection with loosening, and one below-knee amputation was performed for chronic pain. Three cases underwent further surgery to address cysts, and 7 malleolar fractures were reported. Medial gutter pain was experienced by 9% of patients. Overall, our data show excellent early and mid-term survivorship for the Zenith. TM. Total Ankle Replacement. Simple fully-jigged instrumentation allows accurate and reproducible implant alignment

Goals of the study. (1) to investigate the relationships between the bony contours of the knee and the Popliteus Tendon (PT) in the healthy knee and after implantation of a TKA and (2) to analyze the influence of implant sizing. Hypothesis. With an apparently well-sized TKA, the position of the PT during knee flexion is modified compared with the preoperative situation. Method. In 4 fresh frozen cadavers we injected the PT with Barium-Sulfate and a CT-scan was performed from 0° to 140°. We implanted copies of TKAs’ obtained from the manufacturer, made with a non radio-opaque polymer (Acrylonitrile butadiene styrene) with additive manufacturing technology. Each cadaver received either a normosized (cortical fit), oversized (3mm overhang), undersized (3mm under-coverage) or mobile bearing (normosized) prosthesis. The limb was CT-scanned again. 3D-reconstructions were created using Mimics software (Fig 1). The pre-post operative position of the PT was analyzed with Matlab software. We quantified the postoperative posterior deviation of the tendon (PDT). Results. In the normal knee the PT overlaps the posterolateral corner of the tibial plateau, between 0° and 100° of flexion with a maximum overlapping distance of 5.5mm (Fig2). After implantation of a normosized TKA, the PT was displaced posteriorly from full extension to 100° of flexion (Fig 3). Mean PDT was 6.2mm (range 0 to 13; SD=1.2) in extension and 4.8mm (range −1 to 9.8; SD=1.1) at 20° of knee flexion. After implantation of an oversized TKA, PDT was significantly greater than with a normosized TKA, at each angle of flexion: mean PDT was 16.7mm (range 4.4 to 23; SD=0.6) knee in extension (p<0.0001) and 10mm (range 4.4 to 15.7; SD=1.1) at 20° (p<0.0001). The deviation of the PT decreased during knee flexion but remained significant up to full flexion. When an undersized plateau was implanted, the PDT was significantly decreased compared with a normosized implant and the deviation was non significant compared with the preoperative knee. Mean DPT in extension was −0.8mm (range; −3.1 to 1.8; SD=0.3) (p<0.001). This absence of deviation of the PT with an undersized implant was confirmed during the full range of flexion. With a mobile-bearing implant, the deviation of the PT was also decreased compared with the normosized TKA. The mean PDT in extension was −0.6mm (range; −4.6 to 5.9; SD=2.6) (p<0.001). Conclusions. This work demonstrates that the optimal sizing in TKA is very challenging due to the non-anatomic design of current implants. The main finding is that surgeons must analyze sizing in term of volume rather than in term of surface. In other words, most apparently «normosized» TKA, in term of surface coverage are in fact oversized in term of prosthetic volume. It may be advantageous to aim atundersizing tibial implants and to preserve an uncovered area in the posterolateral corner of the resected tibia

Background. The purpose of this study was to assess the overall clinical and radiographic outcomes of unicompartmental knee arthroplasty (UKA) in the 2–10 year postoperative period. The secondary goal was to compare outcomes between fixed- (FB) and mobile-bearing (MB) implant designs. Methods. We performed a retrospective analysis of 237 consecutive primary medial UKAs from a single academic center. All cases were performed by high-volume fellowship-trained arthroplasty surgeons, though UKA comprised <10% of their overall knee arthroplasty practice (<20 medial UKAs per surgeon per year). Clinical outcomes included the Oxford Knee Scores (OKS) and revision rates. Femoral and tibial coronal and sagittal angles (FCA, FSA, TCA, TSA) were radiographically measured. FCA (>±10º deviation from the neutral axis), FSA (>15º flexion), TCA (>±5º deviation from the neutral axis), and TSA (>±5º deviation from 7º) outliers were defined. Far outliers were defined as measurements that fell an additional >±2º outside of these ranges. Outcomes were compared between the FB and MB groups. Results. Overall, OKS scores improved significantly from 18.6 to 34.2 (p<0.0001) following UKA. The overall revision rate at an average 5.5-year follow-up was 14.3%. Only 48.9% and 46.4% of knees simultaneously fell within coronal and sagittal alignment targets for femoral and tibial alignment, respectively. Only 24.1% of all UKAs fell within target alignment in all four measurements. When comparing FB and MB knees, there was no difference in the overall revision rate (12.5% vs. 17.6%, p=0.280), nor were there differences in postoperative OKS (33.6 vs. 35.4, p=0.239) or outlier risk. Conclusions. The proportion of UKA revisions and alignment outliers is greater than expected, even among high-volume surgeons. In general, implant design does not appear to significantly impact clinical outcomes, revision rates, or implant alignment. There was a trend for far outliers to have a higher rate of revision and lower OKS. For figures, tables, or references, please contact authors directly

Background: We have noted a concerning number of early failures (as defined by revision) for Preservation medial mobile-bearing uni-compartmental knee replacements (UKR’s) implanted in our hospital. This study retrospectively reviewed the postoperative radiographs to see if these were as a result of surgical technical failure. Methods: Between 2003 and 2004, 43 medial mobile-bearing Preservation UKR’s were implanted into 39 patients. The average age of the patients at the time of the index procedure was 61.4 years (range, 46–85), (20 males). The immediate post-operative radiographs were reviewed by 2 independent orthopaedic consultants and a registrar, who were blinded to the patient outcomes, using the radiographic criteria used for the Oxford UKR. We however, particularly tried to identify any medio-lateral offset between femoral and tibial components due to the constrained nature of the prosthesis. A compound error score for all other technical errors was also calculated for each patient. Results: Six (13.9%) of 43 knees were revised (5 for persistent pain, 1 for tibial component subsidence). Technical errors were few and no correlation was found between post-operative radiographic appearances and the subsequent need for revision. The mean compound error score (maximum value 18) was 4.5 (range, 2–9) in the revision cases and in the non revised cases 3.2 (range, 0–8). Conclusions: We believe this study gives credence to the opinion that the DePuy Preservation mobile-bearing implant has design faults and is over-constrained leading to early failures in some cases

Introduction: The use of total ankle arthroplasty for the management of end stage arthritis of the ankle is gaining in popularity. We performed a review of the literature on Total Ankle Arthroplasty to assess the methodology of studies and to detect possible variation in the reported surgical outcomes. Material and Methods: All relevant articles in peer-reviewed journals were retrieved except those not mentioning outcomes, case reports, review of literature and letters to editors. Studies reporting on implants presently used, with at least 20 subjects followed for a mean of at least two years were included. Two authors independently scored the quality of the studies using the Coleman Methodology Score (CMS). We collected data for type of study, patient numbers, length of follow-up, complications, outcome and prosthesis survival with revision or fusion as an endpoint. Where appropriate, pooling of data was performed. Results: Twenty-one level IV studies, published from 2003 to 2008, reporting on 2167 ankle replacements followed for a mean of 5.6 years, were included. The CMS was 65 (SD 15), with substantial agreement between the two examiners. Inflammatory arthropathy was present in 31% of ankles. The intra-operative fracture rate was 10.5%. Superficial wound healing complication rate was 6.4%, and deep infections occurred in 1.2% of ankles. Patients’ satisfaction rate was 94%. The failure rate of the primary ankle prosthesis was 11.6% (Agility: 12.2% at 4 years, STAR: 11.7% at 4.6 years and Buechel-Pappas (BP): 12.8% at 7.3 years). Pooling the data the six-year survivorship for the Agility was 0.70 (CI 95%, 0.50–0.90), whereas the 10-year survivorship for the STAR was 0.79 (CI 95%, 0.56–1.00) and for the BP 0.87 (CI 95%, 0.69–1.00). Conclusions: Studies reporting on total ankle arthroplasty are of overall moderate quality. Survivorship analysis revealed superior results for mobile-bearing implants. Patients’ satisfaction rate was high

Introduction: Chronic joint pain is the primary reason for individuals electing to undergo TKR and therefore pain relief is an extremely important outcome after surgery. Although the literature suggests that TKR produces excellent pain relief, the prevalence of chronic pain after TKR is often masked in the reporting of mean pain scores. The aim of this study was to explore the prevalence, impact and onset of pain at 1-year after TKR. Methods: 243 patients (251 knees) were recruited into a multi-centre randomised controlled trial comparing the outcomes of the Kinemax Plus fixed-bearing and mobile-bearing implant. Patients were assessed pre-operatively and then 3 months, 1-year and 2-years post-operatively. At each assessment time patients completed the WOMAC, KOOS quality of life scale, SF-12, American Knee Society Score, Satisfaction Scale for Joint Replacement Arthroplasty and a clinical examination. As part of the clinical assessment patients were asked to rate the pain in their knee as none, mild, occasionally moderate, continually moderate or severe. Results: To date, 240 knees have reached their 1-year follow-up. Complete data regarding pain ratings was available for 198 patients. The mean age of patients was 68 years (range 40–81) and 52% were male. At 1-year after TKR, 13% of patients had occasionally moderate pain, 6% had continually moderate pain and 6% of patients had severe pain. In total, 25% patients reported moderate-severe pain at 1-year after TKR. 60% patients with pain at 1-year post-operative also experienced moderate-severe pain at 3 months post-operative. Using a Mann-Whitney U test, patients with moderate-severe pain at 1-year after TKR had significantly worse physical function (p< 0.001), knee-related quality of life (p< 0.001) and mental health scores (p< 0.05) than those patients with no-mild pain. Conclusion: This study suggests the prevalence of pain after TKR is high, with 25% of patients reporting moderate-severe pain at 1-year after TKR. Pain experienced at 1-year post-operative was most frequently preceded by pain at 3-months post-operative, suggesting that for many patients a pain-free period after surgery is not experienced. The pain present at 1-year after TKR affected several domains of life, including functional ability, quality of life and mental health. Future research will focus on developing a pre-operative screening protocol to identify patients at risk of chronic pain after TKR. This research was supported by funding from Stryker UK

The purpose of this study is to compare the long-term clinical results of two total knee replacement designs (the SAL-II mobile-bearing implant and the fixed-bearing Genesis I implant) to see if there are any advantages to the use of a mobile-bearing design in the long-term. One hundred and ninety-two patients with an age range between twenty-five to ninety who were implanted with either an SAL-II (Group A) or GEN I (Group B) at London Health Sciences Center, University of Western Ontario, were included in the study. Patients with a diagnosis of inflammatory arthritis or with previous high tibial osteotomy were excluded from the study. Demographic data as well as functional outcome measures such as range of motion, knee alignment, specific measures of activities with daily tasks, and composite knee scores such as the Knee Society Clinical Score and Functional Score were collected from the patients’ medical charts and compared. Data was analyzed using SPSS V14.0 statistical software. Group A included eighty-three mobile-bearing platform arthroplasties in seventy-seven patients. There were forty-one males and thirty-six females. The average age of the patients at the time of surgery was 67.7. Average follow up time was 10.56 years from the date of surgery. Eleven patients were excluded from the study, ten due to previous HTO surgery and one due to rheumatoid arthritis. At latest follow-up, ten patients required revision, and fifteen patients died. Group B included one hundred and thirty-one fixed-bearing knee arthroplasties in one hundred and fourteen patients. There were forty-one males and seventy-three females. The average age of the patients at the time of surgery was 65.8. Average follow up time was 9.58 years from the date of surgery. Twenty five patients were excluded from the study, twenty three patients due to previous HTO surgery and two patients due to rheumatoid arthritis. At latest follow-up, thirteen patients required revision, and twelve patients had died. Include Results and p-values at this stage. No statistically significant difference was found between the groups, either for the knee score (p=0.536), the function score (p=0.115), the range of movement (p=0.718) and number of revisions. Ten years survivorship for mobile bearing group was significantly lower than the fixed bearing group (p=0.005) although this equalised at fifteen years. This study is the first long-term study that compares the results of the mobile-bearing and fixed bearing designs performed by the same surgeons in the same period of time. The results of this study show no difference in these two designs at a mean of ten years follow-up although fixed bearing design demonstrated better overall ten years survivorship. This difference can be related to the earlier mobile bearing revisions due to aseptic loosening and instability. Mobile bearing designs have yet to prove their theoretical advantage in clinical practice

Introduction / Purpose. Many factors can influence postoperative knee flexion angle after total knee arthroplasty (TKA), and range of flexion is one of the most important clinical outcomes. Although many studies have reported that postoperative knee flexion is influenced by preoperative clinical conditions, the factors which affect postoperative knee flexion angle have not been fully elucidated. As appropriate soft-tissue balancing as well as accurate bony cuts and implantation has traditionally been the focus of TKA success, in this study, we tried to investigate the influence of intraoperative soft-tissue balance on postoperative knee flexion angle after cruciate-retaining (CR) TKA using a navigation system and offset-type tensor. Methods. We retrospectively analyzed 55 patients (43 women, 12 men) with osteoarthritis who underwent TKA using the same mobile-bearing CR-type implant (e.motion; B. Braun Aesculap, Germany). The mean age at the time of surgery was 74.2 (SD 7.3) years. The exclusion criteria for this study included valgus deformity, severe bony defect requiring bone graft or augmentation, revision TKA, active knee joint infection, and bilateral TKA. Intraoperative soft-tissue balance parameters such as varus ligament balance and joint component gap were measured in the navigation system (Orthopilot 4.2; B. Braun Aesculap) while applying 40-lb joint distraction force at 0°, 10°, 30°, 60°, 90°, and 120° of knee flexion using an offset-type tensor with the patella reduced. Varus ligament balance was defined as the angle (degree, positive value in varus imbalance) between the seesaw and platform plates of the tensor that was obtained from the values displayed by the navigation system. To determine clinical outcome, we measured knee flexion angle using a goniometer with the patient in the supine position before and 2 years after surgery. Correlations between the soft-tissue parameters and postoperative knee flexion angle were analyzed using simple linear regression models. Pre- and postoperative knee flexion angle were also analyzed in the same manner. Results. Mean pre- and postoperative flexion angle were 120.5 ± 1.9° and 121.9 ± 1.3°, which did not show significant improvement after surgery. Varus ligament balance at 90° of flexion was positively correlated with postoperative knee flexion angle (R = 0.56, P < 0.001) and calculated joint gap of the lateral compartment at 90° of flexion showed positive correlation with postoperative knee flexion angle (R = 0.51, P < 0.001), while no correlation was found between joint gap of the medial compartment at 90° of flexion and postoperative knee flexion angle. Also, as with some past studies, joint component gap at 90° of flexion was slightly correlated with postoperative knee flexion angle (R = 0.30, P < 0.05) and pre- and postoperative knee flexion angle showed a significant positive correlation (R = 0.63, P < 0.001). Conclusions. Varus ligament balance at mid to deep flexion was a factor that predicted postoperative knee flexion angle after CR-TKA. In addition to preoperative knee flexion angle and joint component gap at 90° of flexion, lateral laxity at 90° of flexion is one of the most important factors affecting postoperative knee flexion angle

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).

Objectives

The medially spherical GMK Sphere (Medacta International AG, Castel San Pietro, Switzerland) total knee arthroplasty (TKA) was previously shown to accommodate lateral rollback while pivoting around a stable medial compartment, aiming to replicate native knee kinematics in which some coronal laxity, especially laterally, is also present. We assess coronal plane kinematics of the GMK Sphere and explore the occurrence and pattern of articular separation during static and dynamic activities.

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.