Poly(epsilon-caprolactone) as a potential material for a temporary joint spacer

Sepsis of a total joint replacement may not respond to treatment with systemic antibiotics. In these circumstances the treatment is often a two-stage revision of the prosthesis; the infected prosthesis is removed, a period of treatment with an antibiotic-loaded joint spacer ensues, finally a new total joint is implanted once the infection has subsided. A PMMA temporary joint spacer offering a degree of functionality is gaining popularity. Patient activity will cause this temporary implant to wear, releasing potentially damaging PMMA particles into the joint environment. An alternative biodegradable polymer is proposed for use as a temporary joint spacer. This study details initial investigations into the wear behaviour of one such polymer, poly(epsilon-caprolactone). A multi-directional pin-on-plate wear tester was used to assess the performance of poly(epsilon-caprolactone) against a stainless-steel counterface. Two lubricating conditions were studied: distilled water and bovine serum. In water the wear rate of the poly(epsilon-caprolactone), 0.35 x 10(-6) mm3/N m, was comparable to that of polyethylene. However, in bovine serum the wear rate was greater, 18.09 x 10(-6) mm3/Nm. This result compares favourably with PTFE wear rates, suggesting that the wear of poly(epsilon-caprolactone) in this specialised application may be acceptable.