# Is Collum Femoris Preserving Stem (CFP) an Epiphyseal‐Stabilized Prosthesis? A Long‐Term Single‐Center Series Follow Up of 705 Cases

## TL;DR

A long-term study of 705 hip implants found that the Collum Femoris Preserving (CFP) stem behaves more like a distal-stabilized prosthesis than an epiphyseal-stabilized one, with high survival rates but notable bone changes.

## Contribution

The study reclassifies the CFP stem based on long-term radiographic evidence, challenging its original design assumptions.

## Key findings

- The CFP stem had a 95.32% long-term survival rate over 10.4 years.
- Radiographic evidence showed proximal bone resorption and distal sclerosis, indicating distal stabilization.
- CFP stems should be classified as distal-stabilized rather than epiphyseal-stabilized prostheses.

## Abstract

The global increase in total hip arthroplasty (THA) has led to widespread use of cementless femoral stems. The Collum Femoris Preserving (CFP) stem, initially designed as an epiphyseal‐stabilized prosthesis, aims to preserve proximal bone and reduce stress shielding. However, long‐term observations have revealed unexpected proximal bone resorption and distal sclerosis, challenging this classification. This study aims to reassess the fixation pattern and long‐term complications of CFP stems to inform clinical decision‐making.

Between 2006 and 2012, 497 patients (705 hips) were included. The primary outcomes included prosthesis survival, periprosthetic bone remodeling, and clinical outcomes, assessed using the Harris Hip Score (HHS). Kaplan–Meier survival analysis was performed, with endpoints of prosthesis loosening and reoperation. Radiographic data were analyzed to evaluate periprosthetic bone remodeling.

A total of 497 patients (705 hips) with a mean follow‐up of 10.4 years were included. The long‐term survival rate of the CFP stem was 95.32%, with a 97.2% survival rate for aseptic loosening and 95.5% for reoperation. Complications included 2.84% aseptic loosening, 0.99% infection, 0.99% periprosthetic fractures, 0.57% dislocation, and 1.42% heterotopic ossification. The CFP stem, which has not shown signs of aseptic loosening, exhibits radiographic features characteristic of a distal‐stabilized prosthesis.

The long‐term survival rate of the CFP prosthesis was 95.32%. Radiographic findings indicate that the CFP prosthesis should be considered a distal‐stabilized prosthesis rather than the traditionally regarded epiphyseal‐stabilized prosthesis.

The Collum Femoris Preserving (CFP) stem, designed to minimize stress shielding and preserve femoral neck bone stock, demonstrated a 95.32% long‐term survival rate over 10.4 years. Radiographic findings revealed significant proximal femoral bone resorption and distal femoral sclerosis, redefining CFP stems as distal‐stabilized rather than epiphyseal‐stabilized prostheses.