# Evaluation of Zimmer® segmental distal femur mega-prostheses: Patient survival, surgical outcomes and functional outcome

## TL;DR

This study evaluates the Zimmer® Segmental mega-prosthesis for distal femur reconstruction after bone tumor removal, showing low implant failure and amputation rates.

## Contribution

The study provides new clinical data on the performance of the second-generation Zimmer® Segmental mega-prosthesis in distal femur reconstruction.

## Key findings

- The 5-year implant failure risk was 12%.
- The 5-year amputation risk was 2%.
- Patients reported good quality of life with an average EQ-5D index score of 0.88.

## Abstract

•No bumper breakage with second-gen Zimmer® Segmental system.•5-year implant failure risk was 12 %.•5-year amputation risk was 2 %.•EQ-5D index score averaged 0.88.•Mean MSTS score was 17 (57 %).

No bumper breakage with second-gen Zimmer® Segmental system.

5-year implant failure risk was 12 %.

5-year amputation risk was 2 %.

EQ-5D index score averaged 0.88.

Mean MSTS score was 17 (57 %).

Modular knee mega-prostheses are considered the method of choice for reconstruction after resection of malignant bone lesions around the knee. The available literature evaluating Zimmer® Segmental mega-prostheses is sparse. The purpose of the present study is to evaluate the use of Zimmer® Segmental mega-prosthesis for reconstruction of the distal femur, following the resection of bone malignancies and aggressive benign bone tumors.

A retrospective study including 59 consecutive patients (F/M = 35/24), mean age 58 (range 17–86) who underwent reconstructions of the distal femur due to malignant bone lesions (n = 51) or aggressive benign bone tumors (n = 8) from 2017 to 2022. All reconstructions were performed with the most recent Zimmer® Segmental System with the XT Distal Femoral Component. Kaplan-Meier survival analysis was used for evaluation of overall survival. Competing risk analysis was used for assessing cumulative incidence of revision and amputation. Patients were followed until death or end of study (December 31st, 2024). Functional outcome and quality of life was evaluated with Musculoskeletal Tumor Society Score (MSTS), European quality of life − 5 Dimensions score (EQ 5D) and Oxford Knee Score (OKS).

Twenty-eight (n = 28) patients were alive at follow-up. Overall survival after 5-year was 44 % (CI95%: 30–58 %). The risk of implant failure after 1 and 5 years was 8 % (95 %CI 1–16 %) and 12 % (95 %CI 4–20 %) respectively. One patient (2 %) underwent amputation. Mean MSTS score was 17 (57 %) (range 3–30). Mean EQ 5D index score was 0.88 and mean EQ-5D VAS score was 68. OKS demonstrated a mean score of 31.

The Zimmer® Segmental mega-prosthesis in distal femur reconstruction with the improved XT femoral component, demonstrated a relatively low risk of implant failure, and a low risk of amputation. The risk of implant failure was higher among patients who underwent radiotherapy.