Current evidence and future directions for research into the use of tantalum in soft tissue re-attachment surgery
The use of tantalum is well established in orthopaedic surgery. It has a modulus of elasticity that is close to bone and a high yield and ultimate strength allowing it to be used to form large, weight-bearing constructs with a high volumetric porosity conducive to osseointegration. However, its role in soft tissue re-attachment remains undefined due to variable clinical outcomes. Successful re-attachment of tendons to tantalum mega-prostheses, in tumour and revision surgery, has been reported but several authors report almost universal failure of long term soft tissue re-attachment with tantalum patella augments when no residual bone stock is present. It is postulated that these failures are due to a lack of stability of the implants and an inhibitory effect of tantalum on soft tissue integration. Tantalum has previously been considered an excellent biomaterial for soft tissue integration based on animal studies where implants were retrieved and subjected to mechanical testing. However, clinical studies suggest that this soft tissue in-growth does not reliably tolerate the high mechanical loads that are generated in the clinical setting. Furthermore, recent laboratory evidence suggests that tantalum may in fact directly inhibit fibroblasts, limiting the potential for mature collagen fibrillogenesis. This review collates the evidence from laboratory, animal and clinical studies to inform and guide future directions in biomaterial research and to drive improved outcomes for soft tissue re-attachment surgery.