The Nasser-Gavvala-Shirodkar-Botchu Classification: A Classification System for Loosening of Endoprosthetic Replacements.

The indications for femoral endoprosthesis replacement (EPR) use in limb reconstruction have broadened over the last decade. Despite its success, loosening remains the most common reason for failure. No previous system has classified loosening based on the anatomical site in relation to the prosthesis. The aim of this study is to propose a simple reproducible classification system for EPR loosening. Adult patients that underwent a revision EPR for loosening from 1 January 2023-1 May 2025 were included. Radiographs and computed tomography (CT) images were retrospectively reviewed. The grading was developed on radiographs to classify loosening around EPRs as normal (grade 1), loosening at the shoulder (grade 2), loosening around the shaft of the peg (grade 3), loosening below the tip of the prosthesis (grade 4), associated penetration of prosthesis through the cortex (grade 5), and associated fracture (grade 6). A total of 28 patients were included. The majority of patients were male (n = 17; 61%) with a mean age of 50.6 years (SD 16.1). The average time from the index surgery to diagnosis of loosening was 10.1 years (SD 7.6). The most common pattern of loosening was grade 3 (N = 16; 57.1%). Our classification system proposes an easily adopted way to describe all patterns of loosening around EPRs, potentially guiding revision surgical strategies. Standardizing the approach in evaluating loosening will aid in producing national guidelines for managing this complex complication and may help improve future EPR design.