Survival and failure modes of the Compress® spindle and expandable distal femur endoprosthesis among pediatric patients: A multi-institutional study

BackgroundExpandable endoprostheses can be used to equalize limb length for pediatric patients requiring reconstruction following large bony oncologic resections. Outcomes of the Compress® Compliant Pre-Stress (CPS) spindle paired with an Orthopedic Salvage Systemexpandable distal femur endoprosthesis have not been reported.MethodsWe conducted a multi-institutional retrospective study of pediatric patients with distal femoral bone sarcomas reconstructed with the above endoprostheses. Statistical analysis utilized Kaplan-Meier survival technique and competing risk analysis.ResultsThirty-six patients were included from five institutions. Spindle survivorship was 86.3% (95% confidence interval [CI], 67.7-93.5) at 10 years. Two patients had a failure of osseointegration (5.7%), both within 12 months. Twenty-two (59%) patients had 70 lengthening procedures, with mean expansions of 3.2 cm (range: 1-9) over 3.4 surgeries. The expandable mechanism failed in eight patients with a cumulative incidence of 16.1% (95% CI,5.6-31.5) at 5 years. Twenty-nine patients sustained International Society of Limb Salvagefailures requiring 63 unplanned surgeries. Periprosthetic joint infectionoccurred in six patients (16.7%). Limb preservation rate was 91% at 10years.ConclusionsThere is a high rate of osseointegration of the Compress® spindle among pediatric patients when coupled with an expandable implant. However, there is a high rate of expansion mechanism failure and prosthetic joint infections requiring revision surgery.Level of evidenceLevel IV, therapeutic study.