Historically, the outcomes of knee replacement were evaluated based on implant longevity, major complications and range of motion. Over the last recent years however, there has been an intensively growth of interest in the patient's perception of functional outcome. However, the currently used patient related outcome (PRO) scores are limited by ceiling effects which limit the possibility to distinguish between good and excellent results post knee arthroplasty. The Forgotten Joint Score (FJS) is a new PRO score which is not influenced by ceiling effects, therefore making it the ideal instrument to compare functional outcome between various types of implants. It is based on the thought that the ultimate goal in joint arthroplasty is the ability of a patient to forget their artificial joint in everyday life. The aim of this study is to compare the FJS between patients who undergo TKA and patients who undergo medial UKA at least 12 months post-operatively. We hypothesized that the UKA which is less extensive surgical procedure will present better FJS than TKA, even 12 month postoperative. All patients who underwent medial UKA or TKA were contacted 12 months post-operatively. They were asked to complete the FJS, the Western Ontario and McMasters Universities Osteoarthritis index (WOMAC) and the EuroQol-5D (EQ-5D). A priori power analysis was conducted using two-sample t-test. 64 patients in each group were needed to reach 80% power for detecting a 12 point (SD 24) significant difference on the FJS scale with a two-sided significant level of 0.05. A p-value <0.05 was considered as statistically significant.Introduction
Methods
Long-term success of the cementless acetabular component has been depends on amount of bone ingrowth around porous coated surface of the implant, which is mainly depends on primary stability, i.e. amount of micromotion at the implant-bone interface. The accurate positioning of the uncemented acetabular component and amount of interference fit (press-fit) at the rim of the acetabulum are necessary to reduce the implant-bone micromotion and that can be enhancing the bone ingrowth around the uncemented acetabular component. However, the effect of implant orientations and amount of press-fit on implant-bone micromotion around uncemented acetabular component has been relatively under investigated. The aim of the study is to identify the effect of acetabular component orientation on implant-bone relative micromotion around cementless metallic acetabular component. Three-dimensional finite element (FE) model of the intact and implanted pelvises were developed using CT-scan data [1]. Five implanted pelvises model, having fixed antiversion angle (25°) and different acetabular inclination angle (30°, 35°, 40°, 45° and 50°), were generated in order to understand the effect of implant orientation on implant-bone micromotion around uncemented metallic acetabular component. The CoCrMo alloy was chosen for the implant material, having 54 mm outer diameter and 48 mm bearing diameter [1]. Heterogeneous cancellous bone material properties were assigned using CT-scan data and power law relationship [1], whereas, the cortical bone was assumed homogeneous and isotropic [1]. In the implanted pelvises models, 1 mm diametric press-fit was simulated between the rim of the implant and surrounding bone. Six nodded surface-to-surface contact elements with coefficient of friction of 0.5 were assigned at the remaining portion of the implant–bone interface [1]. Twenty-one muscle forces and hip-joint forces corresponds to peak hip-joint force of a normal walking cycle (13%) were used for the applied loading condition. Fixed constrained was prescribed at the sacroiliac joint and pubis-symphysis [1]. A submodelling technique was implemented, in order to get more accurate result around implant-bone interface [1].Introduction
Materials and Method
Two fixed bearing options exist for tibial resurfacing when performing unicompartmental knee arthroplasty (UKA). Inlay components are polyethylene-only implants inserted into a carved pocket on the tibial surface, relying upon the subchondral bone to support the implant. Onlay components have a metal base plate and are placed on top of a flat tibial cut, supported by a rim of cortical bone. To our knowledge, there is no published report that compares the clinical outcomes of these two implants using a robotically controlled surgical technique. We performed a retrospective review of a single surgeon's experience with Inlay versus Onlay components, using a robotic-guided protocol. All surgeries were performed using the same planning software and robotic guidance for execution of the surgical plan (Mako Surgical, Fort Lauderdale, FL). The senior surgeon's prospective database was reviewed to identify patients with 1) medial-sided UKA and 2) at least two years of clinical follow up. Eighty-six patients met these inclusion/exclusion criteria: 41 Inlays and 45 Onlays. Five patients underwent a secondary or revision procedure during the follow up period and were considered separately. Our primary outcome was the WOMAC score, subcategorized by the Pain, Stiffness, and Function sub-scores. The secondary outcome was need for secondary surgery. Continuous variables were analyzed using the two-tailed Student's t-test; categorical variables were analyzed using Fisher's exact test.Introduction:
Methods:
