Abstract
Introduction
Although total knee arthroplasty (TKA) has become a successful routine procedure in clinical orthopaedics, up to 20% of patients are not satisfied with the outcome of their surgery. Dissatisfaction in high-demand patients has been associated with the functional limitations of conventional TKA implants, as they do not recreate the natural biomechanics of the knee.
A novel knee prosthesis has been designed to replicate the natural rolling & gliding mechanism of the knee joint, aiming to restore a physiological movement whilst improving implant stability and pain-free function.
This TKR system includes 3 versions (CR, PS, KR); the KR (Kinematic Retaining) preserves the posterior cruciate ligament (PCL); the femoral component incorporates a thin anterior flange and a deep, broad trochlear groove to reduce anterior knee pain and to reproduce physiological patellar tracking without constraining the patella. The sagittal plane multiple radii of the femoral condyles (J-curve) allows the carefully designed femur to physiologically tension the collateral ligaments during the entire flexion/extension cycle. Tibial liners are also asymmetrical, presenting a concave medial shape with a saddle-like lateral shape. These asymmetric articulating surfaces have been designed to reproduce a more natural physiological roll-back and rotation of the femur over the tibia, thus reducing the sliding friction in the early phases of knee flexion. Furthermore, the roll-back motion relieves the stress from the patella and restores the physiological function of the quadriceps.
Objectives
Aim of this retrospective study was to assess the first clinical and radiographic outcomes after TKA with the Physica Kinematic Retaining (KR) knee system.
Methods
Between October 2013 and November 2014, 60 patients (60 knees) underwent TKA with the Physica KR knee system (Lima Corporate, Italy) at two centres in two different countries. A standard parapatellar and a mid-vastus approach were used in 24 and 36 cases, respectively. There were 32 women and 28 men, with a mean age and BMI of 63 (range 44–73) years and 29 (range: 21–36) kg/m2, respectively. Patients were affected mainly by osteoarthritis (95%). Clinical and radiographic assessments were carried out preoperatively, and postoperatively at 6, 12 and 18 months, using the Knee Society Score (KSS) and standard radiographs.
Results
Mean Knee Society Score increased significantly from 55 (range: 21–77) at the preoperative time to 94 (range: 86–100) at the last follow-up. High levels of patient satisfaction were reported. Most improvements were observed in terms of early patient mobilisation, fast functional recovery and pain relief. No cases of radiolucent lines, loosening or implant migration were reported. No revision and infections were reported.
Conclusions
Short-term clinical and radiographic outcomes of the Physica KR Knee system are encouraging. While reproducing the kinematics of the natural knee, this novel prosthetic implant has ensured a fast functional recovery and pain relief, even in high-demand patients.
