Aim. To investigate the effect of the eight plate position in sagittal plane on
Introduction and Objective. After anterior cruciate ligament reconstruction one of the risk factors for graft (re-)rupture is an increased posterior tibial slope (PTS). The current treatment for PTS is a high tibial osteotomy (HTO). This is a free-hand method, with 1 degree of
Objectives. Unicompartmental knee arthroplasty (UKA) is a demanding procedure, with tibial component subsidence or pain from high tibial strain being potential causes of revision. The optimal position in terms of load transfer has not been documented for lateral UKA. Our aim was to determine the effect of tibial component position on proximal tibial strain. Methods. A total of 16 composite tibias were implanted with an Oxford Domed Lateral Partial Knee implant using cutting guides to define
Introduction. With the development of 3D printing technology, there are many different types of PSI in the world. The accuracy of patient specific instrumentation (PSI) in primary total knee arthroplasty (TKA) is dependent on appropriate placement of the cutting blocks. However, previous reports on one type of PSI measured the difference between postoperative prosthetic alignment and postoperative mechanical axis and thus these reports did not evaluate intraoperative comparison of PSIs between two different designs. The purpose of this study was to evaluate the intraoperative accuracy of two different designed PSIs (My knee, Medacta International, Castel San Pietro, Switzerland) with two examiners using CT free navigation system (Stryker, Mahwar, NJ, USA) in regards to sagittal and coronal alignment. Methods. We enrolled 78knees (66 patients) with a primary cemented TKA using two different designed CT-based PSIs (My knee, Medacta International, Castel San Pietro, Switzerland). All operations were performed by two senior surgeons who have experience with greater than 500 TKAs and greater than 200 navigated TKAs. Two examiners were same two surgeons. The study period was between June 2015 and November 2016. The local ethics' committee approved the study prior to its initiation, and informed consent was obtained from all patients. After placement of the PSI on the femur and tibia, the position of the PSI was evaluated by s intraoperative navigation. Two examiners placed two different types (STD(standard) and MIS(minimum invasive surgery)) of PSI on same joint. As required by the PSI, only soft- tissue was removed and osteophytes were left in place. Femoral MIS PSI was required partial remove of lateral cartilage. For the femur, the coronal position in relation to the mechanical axis were documented. For the tibia, the coronal alignment and the
One of the main surgical goals when performing a total knee replacement (TKR) is to ensure the implants are properly aligned and correctly sized; however, understanding the effect of alignment and rotation on the biomechanics of the knee during functional activities is limited. Cardiff University has unique access to a group of local patients who have relatively high frequency of poor alignment, and early failure. This provides a rare insight into how malalignment of TKR's can affect patients from a clinical and biomechanical point of view to determine how to best align a TKR. This study aims to explore relationship clinical surgical measurements of Implant alignment with in-vivo joint kinematics. 28 patient volunteers (with 32 Kinemax (Stryker) TKR's were recruited. Patients undertook single plane video fluoroscopy of the knee during a step-up and step-down task to determine TKR in-vivo kinematics and centre of rotation (COR). Joint Track image registration software (University of Florida, USA) was used to match CAD models of the implant to the x-ray images. Hip-Knee-Ankle (HKA) was measured using long-leg radiographs to determine frontal plane alignment. Posterior tibial slope angle was calculated using radiographs. An independent sample t-test was used to explore differences between neutral (HKA:-2° to 2°), varus (≥2°) and valgus alignment (≤-2°) groups. Other measures were explored across the whole cohort using Pearson's correlations (SPSS V23). There was found to be no statistical difference between groups or correlations for HKA. The exploratory analysis found that
Achieving deep flexion after total knee replacement remains a challenge. In this study we compared the soft-tissue tension and tibiofemoral force in a mobile-bearing posterior cruciate ligament-sacrificing total knee replacement, using equal flexion and extension gaps, and with the gaps increased by 2 mm each. The tests were conducted during passive movement in five cadaver knees, and measurements of strain were made simultaneously in the collateral ligaments. The tibiofemoral force was measured using a customised mini-force plate in the tibial tray. Measurements of collateral ligament strain were not very sensitive to changes in the gap ratio, but tibiofemoral force measurements were. Tibiofemoral force was decreased by a mean of 40% (