# Application of the LEG NUI score to assess revision success in established distal femur non-unions

## TL;DR

This study evaluates a scoring system to predict the need for further surgery in patients with non-healing distal femur fractures after revision.

## Contribution

The LEG NUI Score is tested for its utility in predicting outcomes in revision surgeries for established non-unions.

## Key findings

- The union rate after the first revision surgery was 55.5%.
- The LEG NUI Score was significantly lower in patients with healed non-unions.
- The score showed moderate predictive ability with an AUC of 0.755.

## Abstract

The incidence of non-union following distal femur fractures is high. Management of persis-tent non-unions is challenging, often requiring multiple revision surgeries, thereby increasing patient morbidity and socioeconomic burden. Identifying patients at high risk for persistent non-union after revision is therefore crucial. The LEG NUI Score was originally developed to predict the need for early intervention following primary fixation of distal femur fractures. This study aimed to evaluate the LEG NUI Score's ability to predict the need for further revision surgery in a cohort of patients with established distal femur non-union undergoing their index revision procedure.

45 patients with complete clinical data were identified from a non-union database. The LEG NUI Score was calculated for the index revision procedure and assessed in relation to the healing out-come of the revision treatment. Comparative statistics and test characteristics were assessed, as well as a receiver operator characteristic analysis was performed. Only patients with uneventful healing after the first treatment were considered healed for the score calculation. Patients requiring more than one surgery, including second step masquelet were considered non-healers.

The union rate (healed non-unions) after the first non-union revision surgery was 55.5 %. 24.4 % of patients had an infected non-union. The average LEG NUI Score in patients with non-union healing was significantly lower than non-healing patients (3.36 ± 1.80 vs. 4.90 ± 1.21; p < 0.05). The AUC in the ROC Analysis was 0.755.

The LEG NUI Score shows potential applicability in the setting of revision surgery for established distal femur non-unions. Calculating the score may help surgeons identifying patients at in-creased risk for requiring subsequent surgical procedures, thus warranting closer postoperative surveillance. Further validation in larger cohorts is required to fully elucidate its clinical utility in this context.

Level III, Retrospective Cohort Study.