Intra-articular compressive stress of the elbow joint in extension: an experimental study using Fuji films.

The use of Fuji films is simple but their manipulation and result interpretation seem to be difficult in the framework of medical research. The reliability and reproducibility of Fuji films have been proved by many previous studies. This study was undertaken to know precisely the articular zones of the elbow and to determine the compressive stress these areas undergo during different activities, in order to assess the importance of different articular contact areas. These data indicate the need for better-adapted elbow prosthesis and can be eventually used to design more durable prosthesis for the elbow. The compressive stress on the radial head was less than 25% in extension. The stress on the radial head varied from the neutral position (23% of the stress), to full pronation (11% of the stress) and to full supination (6% of the stress). The Humero-ulnar compartment had the maximum impact. Coronoid process seemed to be a fundamental element of the elbow joint in extension (60% of total compressive stress). The Medial humero-ulnar compartment was less stressed than the lateral compartment. The radial head does not seem to play a major role in the stability of the elbow in extension if the ulnar collateral ligament exists. The ulnar collateral ligament is essential to the elbow joint stability. The lifespan of a non-constrained prosthesis would depend on the existence of the couple: radial head/ulnar collateral ligament; the absence of radial head could compromise the humero-ulnar stability. This work paved the way for the designing of new non-constrained elbow prosthesis with the reconstruction of the radial head.