Antibiotic delivery by absorbable collagen implant during posterior approach hip resurfacing arthroplasty

Post-operative surgical deep space infection is major complication of hip arthroplasty surgery that in many instances may require management by repeated surgical procedures or implant revision. Localised delivery of gentamicin impregnated collagen implants can reduce surgical site infection rates and have been shown to deliver elevated concentrations without clinically significant systemic elevation in anterior total hip arthroplasty. However, to date no evaluation of posterior approach hip resurfacing arthroplasty has been completed. Anterior approach hip arthroplasty (n=32) and posterior approach hip arthroplasty (n=30) procedures were compared in this study. Local and systemic gentamicin levels were measured after implanting gentamicin impregnated collagen carriers (Collatamp® G, Syntacoll GmbH, Saal/Donau, Germany) within 24 hours of surgery for comparison of concentrations obtained by either surgical approach. The median gentamicin concentrations for wound aspirates after anterior and posterior approach hip arthroplasty procedures were 70.48 (±55.93) mg/L and 83.60 (±78.77) mg/L respectively. The median concentrations for serum gentamicin levels anterior and posterior hip arthroplasty approaches were 0.74 (±0.48) mg/L and 0.47 (±0.67) mg/L respectively. The results of this study indicated that wound aspirate gentamicin levels are significantly (p <0.01) greater than serum gentamicin levels after implantation of Collatamp G devices after both anterior and posterior surgical approach hip arthroplasty procedures. There was no significant ( p <0.01) differences between wound aspirate gentamicin levels when comparing between anterior and posterior surgical approach. There were no significant (p <0.01) differences between serum gentamicin levels when comparing between anterior and posterior surgical approach. Collectively these results demonstrated that clinically significant gentamicin levels can be achieved via implantation of absorbable collagen implants without corresponding serum levels when sampled within 24 hours post-surgery. The research suggests that the greater levels of antibiotic achieved at the wound site may be advantageous to clinical outcomes in orthopaedic wound sites.