Patient-specific (PS) implantation surgical technology has been introduced in recent years and a gradual increase in the associated number of surgical cases has been observed. PS technology uses a patient’s own geometry in designing a medical device to provide minimal bone resection with improvement in the prosthetic bone coverage. However, whether PS unicompartmental knee arthroplasty (UKA) provides a better biomechanical effect than standard off-the-shelf prostheses for UKA has not yet been determined, and still remains controversial in both biomechanical and clinical fields. Therefore, the aim of this study was to compare the biomechanical effect between PS and standard off-the-shelf prostheses for UKA. The contact stresses on the polyethylene (PE) insert, articular cartilage and lateral meniscus were evaluated in PS and standard off-the-shelf prostheses for UKA using a validated finite element model. Gait cycle loading was applied to evaluate the biomechanical effect in the PS and standard UKAs.Objectives
Methods
Posterior condylar offset (PCO) and posterior tibial slope (PTS) are critical factors in total knee arthroplasty (TKA). A computational simulation was performed to evaluate the biomechanical effect of PCO and PTS on cruciate retaining TKA. We generated a subject-specific computational model followed by the development of ± 1 mm, ± 2 mm and ± 3 mm PCO models in the posterior direction, and -3°, 0°, 3° and 6° PTS models with each of the PCO models. Using a validated finite element (FE) model, we investigated the influence of the changes in PCO and PTS on the contact stress in the patellar button and the forces on the posterior cruciate ligament (PCL), patellar tendon and quadriceps muscles under the deep knee-bend loading conditions.Objectives
Methods
Patient satisfaction is becoming increasingly important as a crucial outcome measure for total knee arthroplasty (TKA). We aimed to determine how well commonly-used clinical outcome scales correlate with patient satisfaction after TKA. In particular, we sought to determine whether patient satisfactions correlate better with absolute postoperative scores or preoperative to 12-month postoperative changes. Patient satisfaction was evaluated using four grades (enthusiastic, satisfied, noncommittal, and disappointed) for 438 replaced knees that were followed for longer than one year. Outcomes scales used AKS, WOMAC and SF-36 scores. Correlation analyses were performed to investigate the relation between patient satisfaction and the 2 different aspects of the outcome scales: postoperative scores evaluated at latest follow-ups and pre- to postoperative changes. The WOMAC function score was most strongly correlated with satisfaction (correlation Coefficient = 0.45). Absolute postoperative scores were better correlated with satisfaction than the pre- to postoperative changes for all scales. This study demonstrates that patient satisfaction correlates better with patient-derived and disease specific scales (WOMAC) than physician-driven (AKS) or generic (SF-36) measures. The present study also shows that absolute postoperative status is more important pre- to postoperative change when determining patient satisfaction.