Functional outcome of infected endoprosthesis: A 20-year retrospective analysis

Purpose: Bone tumours are increasingly treated with limb-salvage surgeries. However, implant infection is a devastating complication, greatly affecting the functional outcome. Yet, data on functional outcome post-implant infection are scarce. This study aims to determine the functional outcome and implant survival of these patients. Methods: Patients' data on endoprosthetic replacement surgeries at our institution (January 1996–December 2016) was retrospectively reviewed. Information was available for 161 patients and was analysed using SPSS and SMART Partial Least Squares. Functional outcome was determined using the Musculoskeletal Tumor Society (MSTS) and Toronto Extremity Salvage Score (TESS) scoring system. Results: Both mean rank MSTS (33.14 vs 87.02) and TESS (48.17 vs 85.13) scores were significantly lower in the infected group. These differences remained statistically significant after excluding amputation and rotationplasty cases within the infected group. Even after the resolution of infection, both MSTS and TESS remained significantly higher in the non-infected group. However, analysis of the infected group showed no significant differences in functional outcome between persistent and resolved infections (implant in-situ). Age significantly impacted the functional outcome for both the non-infected and infected groups, while local recurrence and metastasis significantly impacted the non-infected cases. Local tumour recurrence was lower in infected endoprosthetic patients (8.3% vs 10.5%). 56% of infected implants were removed; the majority were treated with two-stage revision surgery. Conclusion: Endoprosthesis infection worsens the overall functional outcome. Additional factors affecting functional outcome were age, presence of local recurrence and metastatic disease. Local tumour recurrence was lower amongst infected endoprosthesis cases, and >50% of infected implants were removed.