Measurement of meniscofemoral contact pressure after repair of bucket-handle tears with biodegradable implants

Introduction Biodegradable implants are frequently used for meniscus repair. Articular cartilage damage has been reported recently after meniscus repair with biodegradable implants. The aim of the study was to investigate the meniscofemoral contact pressure at the posterior horn of the medial and lateral meniscus after repair of bucket-handle lacerations. Materials and methods Specimens were mounted in a materials testing machine (Bionix 858, MTS) which was equipped with a load cell. The quadriceps tendon was attached to a hydraulic cylinder, and knee motion was controlled via tension of the quadriceps tendon. A piezo-resistive system (Tekscan, Boston, MA, USA) measured the meniscofemoral contact pressure. Five different types of biodegradable implants ( Arrow, Dart, Fastener, Stinger and Meniscal Screw) and horizontal suture ( no. 2 Ethibond) were tested. The knee was extended from 90 degrees of flexion to 0 degrees under a constant load of 350 N due to adjustment of the tension force of the quadriceps tendon. The femorotibial pressure and contact area were recorded at 0 degrees, 30 degrees, 60 degrees and 90 degrees of flexion. Results The meniscofemoral pressure did not increase after meniscus repair with biodegradable implants or sutures. The meniscofemoral peak pressure at the posterior horn was 1.46 +/- 1.54 MPa in the medial compartment and 1.08 +/- 1.17 MPa in the lateral compartment at full knee extension. The meniscofemoral pressure increased significantly in both compartments with knee flexion from 0 degrees to 90 degrees. Conclusion Biodegradable implants for meniscus repair do not affect the meniscofemoral pressure. However, there remains a risk of damage to the cartilage when barbed implants are used. If the implant is not entirely advanced into the meniscus, the sharp head or some of the barbs at the column of the implant may come into direct contact with the articular cartilage of the femoral condyle or tibial plateau. The authors presume that incorrect positioning of the implant seems to be the major reason for cartilage damage.