How to predict structural allograft survival in tibial reconstructions.

Tibial reconstruction for major bone loss is a challenging surgical situation. For more than 30 years, massive bone allografts entered our therapeutic arsenal as a major tool to reconstruct large bone defect. Despite allograft is valued for its convenience, it is still burdened by a high complication rate. This retrospective monocentric study focuses on the clinical outcomes of massive tibial allografts and their outcome's prediction. Between 1987 and 2022, the files of 148 massive tibial allografts were retrospectively reviewed (registration number B403201523492). Survival curves were calculated based on the allograft success or failure. Survival curves without revision surgery were calculated following the same design. Finally, multiple logistic regression models were set up to point out variables that influence the allograft survival. After 30 years, 87.2% of the patient retained limb function. However, 55% of the allograft failed and had to be removed (mean survival time is 20.06 ± 2.07 years (CI 16.0-24.1)). The estimate mean survival time is 10.26 ± 1.60 years (CI 7.1-13.4) with less than 20% survival for the allografts without revision surgery after 30 years. Tumor and septic indications worsen the prognosis as well as the number of revision surgeries and the osteochondral allograft type. In contrast, PSI use or traumatological indications improve the allograft survival. Despite remaining an excellent surgical reconstructive option, massive tibial allografts show a high revision surgery rate. Thanks to our multiple logistic regression models, we can start to predict and improve the final outcomes of these complex allograft reconstruction.