Endoprosthetic replacement of the proximal tibia for oncological conditions

Aims The proximal tibia (PT) is the anatomical site most frequently affected by primary bone tumours after the distal femur. Reconstruction of the PT remains challenging because of the poor soft-tissue cover and the need to reconstruct the extensor mechanism. Reconstructive techniques include implantation of massive endoprosthesis ( megaprosthesis), osteoarticular allografts (OAs), or allograft-prosthesis composites (APCs). Methods This was a retrospective analysis of clinical data relating to patients who underwent proximal tibial arthroplasty in our regional bone tumour centre from 2010 to 2018. Results A total of 76 patients fulfilled the inclusion criteria and were included in the study. Mean age at surgery was 43.2 years (12 to 86 (SD 21)). The mean follow-up period was 60.1 months (5.4 to 353). In total 21 failures were identified, giving an overall failure rate of 27.6%. Prosthesis survival at five years was 75.5%, and at ten years was 59%. At last follow-up, mean knee flexion was 89.8 degrees (SD 36 degrees) with a mean extensor lag of 18.1 degrees (SD 24 degrees). In univariate analysis, factors associated with better survival of the prosthesis were a malignant or metastatic cancer diagnosis (versus benign), with a five- and ten-year survival of 78.9% and 65.7% versus 37.5% (p = 0.045), while in-hospital length of stay longer than nine days was also associated with better prognosis with five- and ten-year survival rates at 84% and 84% versus 60% and 16% (p < 0.001). In multi-variate analysis, only in-hospital length of stay was associated with longer survival (hazard ratio (HR) 0.23, 95% confidence interval (CI) 0.08 to 0.66). Conclusion We have shown that proximal tibial arthroplasty with endoprosthesis is a safe and reliable method for reconstruction in patients treated for orthopaedic oncological conditions. Either modular or custom implants in this series performed well.