# Factors Associated with Bone Union Failure After Frozen Autograft Reconstruction in Lower Limb Osteosarcoma

## TL;DR

This study finds that using intramedullary nails increases the risk of bone nonunion after frozen autograft surgery for lower limb osteosarcoma, while multiple-plate fixation improves healing outcomes.

## Contribution

The study identifies fixation method as a critical factor in bone union success after frozen autograft reconstruction for osteosarcoma.

## Key findings

- Intramedullary nail fixation was strongly associated with nonunion (40% nonunion rate) compared to plate fixation (8% nonunion rate).
- Multiple-plate fixation resulted in lower nonunion rates (5.6%) compared to single-plate fixation (14.3%).
- Mean union time was shorter with plate fixation (5.8 months) than with intramedullary nails (7.2 months).

## Abstract

Liquid nitrogen-treated frozen autograft is a distinctive biological reconstruction method developed at Kanazawa University for patients with malignant bone tumors. Although this technique preserves the patient’s own bone and avoids prosthetic replacement, bone union between the frozen graft and host bone remains challenging. We studied 35 patients with osteosarcoma of the lower limb long bones to identify factors influencing bone union. Fixation with intramedullary nails was strongly associated with nonunion, whereas plate fixation, particularly with multiple plates, achieved more reliable healing, supporting plate fixation as the preferred method to reduce the risk of nonunion in frozen autograft reconstruction.

Background/Objectives: Liquid nitrogen-treated frozen autograft is a biological reconstruction method developed at Kanazawa University for malignant bone tumors. However, nonunion between the treated autograft and host bone remains a complication. In this study, we aimed to identify factors influencing bone union in patients undergoing this procedure for osteosarcoma of long bones in the lower extremities. Methods: We retrospectively analyzed 35 osteosarcoma patients (mean age: 18.0 years) with lower limb long bone tumors treated with frozen autograft between 1999 and 2023. Factors assessed included sex, age, tumor location, fixation method (plate or intramedullary nail), technique (pedicle or free freezing), chemotherapy, and bone union. Results: Nonunion occurred in 6 cases: 2/25 with plate fixation (8.0%) and 4/10 with intramedullary nails (40%). The mean union time was shorter with plates (5.8 months) than with nails (7.2 months). Intramedullary nail use was significantly associated with nonunion (p < 0.05). Among plate fixations, nonunion occurred in 5.6% of multiple plates versus 14.3% of a single plate. Conclusions: Intramedullary nail fixation is associated with nonunion in biological reconstructions of long bones, consistent with previous reports. Multiple-plate fixation after frozen autograft with liquid nitrogen for osteosarcoma of the lower limb long bone should be considered.