Mechanical stabilization following periprosthetic fractures is challenging. A variety of cable and crimping devices with different design configurations are available for clinical use. This study evaluated the mechanical performance of 5 different cable systems in vitro. The effect of crimping device position on the static failure properties were examined using a idealized testing set up. Five cable systems were used in this study; Accord (Smith & Nephew), Cable Ready (Zimmer), Dall-Miles (Stryker), Osteo Clage (Acumed) and Control Cable (DePuy). Cables were looped over two 25 mm steel rods. Cable tension was applied to the maximum amount using the manufactures instrumentation. Devices were crimped by orthopaedic surgeon according to instructions. Crimping device/sleeve was secured in two different positions; 1. Long axis in-line with the load; 2. Long axis perpendicular to the load (Fig 1). Four constructs were tested for each cable system at each position. All constructs were tested following equilibration in phosphate buffered saline at 37 degrees Celsius using a servohydraulic testing machine (MTS 858 Bionix Testing Machine, MTS Systems) at a displacement rate of 10 mm per minute until failure. The failure load, stiffness and failure model (cable failure or slippage) was determined for all samples. Data was analysed using a two way analysis of variance (ANOVA) followed by a Games Howell post hoc test. One sample of each cable – crimping construct was embedded in PMMA and sectioned to examine the crimping mechanism.Introduction
Materials and Methods
Articular cartilage defects of the knee occur commonly in sports injuries and trauma. Increasing evidence suggests that the only technique that enables the regeneration of articular hyaline cartilage in chondral defects is autologous chondrocyte implantation (ACI). Here we have reported our clinical experience of autologous chondrocyte implantation using biodegradable type I/III collagen membrane (CACI). A total of 26 patients (age range from 19 to 60 years, average 37 years) was conducted with CACI. Pre-operative magnetic resonance imaging (MRI) scans were performed on all patients. Post-operative MRI scans were planned for approximately three and 12 months after the surgery to determine the success of integration of implanted chondrocytes. The results demonstrated that the initial post-operative MRI scans at three months showed the presence of oedematous tissue at the defect sites in 23 patients, contrasting with the fluid filled defects seen preoperatively and with and MRI signal differing from that of the surrounding normal hyaline articular cartilage. MRI scans in nine patients at 12 months after their operations showed maturation of cartilage graft in all patients. Apopototic testing of the chondrocytes using Annexin IV before implantation showed that the viability of the chondrocytes was over 85% where the apopototic rate of chondrocytes was less than 2%. One patient with an apopototic rate of over 10% has a delayed repair in cartilage defects as shown by MRI. In conclusion, early phase clinical studies showed that autologous chondrocyte implantation remains promising for the treatment of chondral defects with restoration of hyaline cartilage. Longer clinical follow-up of the patients and better assessment of cellular phenotype of chondrocytes before implantation are required.
