To improve implant positioning in total knee arthroplasty (TKA) patient-specific instrumentation (PSI) has been introduced as alternative for conventional instrumentation (CI). Though the PSI technique offers interesting opportunities in TKA, there is no consensus about the effectiveness of PSI in comparison with CI and results concerning soft-tissue balancing remain unclear. Therefore, the primary aim of the present study was to investigate the varus-valgus laxity in extension and flexion in patients receiving a TKA using PSI compared with CI. Additionally, radiological, clinical and functional outcomes were assessed. In this prospective randomization controlled trial, 42 patients with osteoarthritis received a Genesis II PS (Smith & Nephew, Memphis, Tennessee), with either PSI (Visionaire, Smith & Nephew) or CI (Smith & Nephew). Patients visited the hospital preoperative and postoperative after 6 weeks, 3 and 12 months. One-year postoperative varus-valgus laxity was measured in extension and flexion on stress radiographs. Additional assessments included: the hip-knee-ankle angle on long-leg radiographs, femoral and tibia component rotation on CT-scans, radiolucency, the Knee Society Score (KSS), VAS pain, VAS Satisfaction, Knee injury and Osteoarthritis Outcome score (KOOS), Patella score (Kujala), the University of California Los Angeles activity score (UCLA), the anterior-posterior laxity in 20° and 90° knee flexion, adverse events and complications. The outcome measures were compared using independent t-tests, non-parametric alternatives and repeated measurements, with a significance level of p<0.05.Background
Methods
An important factor in the functional results after total knee arthroplasty (TKA) is the achieved maximal flexion. To date, a TKA still provides dissimilar flexion capabilities compared to the healthy knee, which could be due to the mismatch between the normal knee geometry and the implant geometry. The implant design of the Journey (Smith&Nephew) aims to replicate the normal knee function. According to the manufacturer of the Journey system, it intends to replicate PCL and ACL function, accommodates deep flexion, induces normal tibiofemoral axial rotation and provides proper patellar tracking throughout the entire range of flexion (‘guided motion’). The objective of this study is to investigate the maximal knee flexion one year after surgery of the Journey and its predecessor the Genesis II (Smith&Nephew). In addition, clinical and functional outcomes will be evaluated. A total of 124 patients presenting with noninflammatory osteoarthritis received the Journey or the Genesis II prosthesis, by randomization. The primary outcome was defined as the maximum flexion angle on a lateral X-ray performed with the patient lying on a bench and using manual force on bending the knee. Secondary outcomes were: active flexion (lying and standing), Knee Society System score (KSS), Patella Scoring System (PSS), number of adverse events (AE) and satisfaction. The changes in KSS and PSS between the pre-operative situation and 1 year after surgery were calculated as: δKSS = KSS1 year – KSSpre-op, and δPSS = PSS1 year – PSSpre-op. Two-sided t-tests and non-parametric alternatives were performed in order to test for differences between the Journey and the Genesis II group.Introduction
Methods
