# Custom Hydroxyapatite‐Coated Stem Collar With Extracortical Plate Provides Excellent Long‐Term Results Against Aseptic Loosening in Revision, Including Short‐Segment, Endoprosthetic Tumour Reconstruction

## TL;DR

A custom implant design with a hydroxyapatite coating and extracortical plate effectively prevents aseptic loosening in long-term revision surgeries for bone tumor reconstructions.

## Contribution

A novel custom implant design that prevents aseptic loosening in challenging revision and short-segment tumor reconstructions.

## Key findings

- No aseptic loosening was observed in 15 patients over a 12-year follow-up.
- Improved joint range of motion and reduced limb-length discrepancy were reported.
- Higher bone ingrowth scores were associated with specific implant features and surgical factors.

## Abstract

Aseptic loosening from endoprosthetic reconstructions following bone tumour resection is a major issue, especially in the revision/multiple revisions settings. The objective was to present long‐term outcomes of revision limb salvage surgery using a custom hydroxyapatite‐coated stem collar with an extracortical plate at the bone‐implant junction specifically designed to prevent aseptic loosening.

Fifteen (15) patients with an initial extremity bone tumour resection and reconstruction who underwent revision surgery utilizing this implant specification between 2004 and 2016 were included. Multiple prior surgeries and short‐segment stem fixation (< 100 mm) were observed in six and nine patients, respectively. Outcomes of interest were rates of aseptic loosening and radiographic evidence of osseointegration along with clinical and functional outcomes.

At mean 12‐year follow‐up (range 6.5 to 18), no patient had evidence of radiographic or clinical aseptic loosening. The distal femur location (p = 0.044), endoprosthetic reconstruction as index procedure (p = 0.026), mechanical failure as reason for revision (p = 0.0047) and additional fixation to the extracortical plate (p = 0.041) were associated with higher bone ingrowth scores. All but two patients, who had mild pain only, were pain‐free. Joint range of motion (p < 0.0001) and limb‐length discrepancy (p = 0.021) significantly improved. The mean Musculoskeletal Tumor Society score was 26.1 (excellent).

This study demonstrated excellent results in preventing long‐term aseptic loosening with this custom implant specification, which is useful particularly for revisions/multiple revisions and short‐segment fixation. However, further larger scale and multicentric studies are needed to validate the data to the broader population.