Radial shortening osteotomy reduces radiocapitellar contact pressures while preserving valgus stability of the elbow

Abstract

Purpose: Shortening osteotomy of the proximal radius might represent a potential salvage procedure in symptomatic radiocapitellar osteoarthritis, which could decrease radiocapitellar load while preserving the native radial head. In an in-vitro biomechanical investigation, we sought to determine whether shortening osteotomy of the proximal radius (1) decreases the radiocapitellar joint pressure upon axial loading and (2) retains valgus stability of the elbow. In addition, the anatomic configuration of the lesser sigmoid notch was evaluated to assess possible contraindications.

Methods: Axial loading (0-400 N) and valgus torque (7.5 N m) over the full range of motion were applied to 14 fresh-frozen specimens before and after shortening osteotomy of the proximal radius by 2.5 mm. Radiocapitellar and ulnohumeral load distribution during axial compression was evaluated using a digital pressure mapping sensor. Valgus displacement was analyzed with a 3D camera system. The inclination angle (α) of the lesser sigmoid notch was assessed via 50 CT scans.

Results: Up to axial loading of 250 N, shortening osteotomy caused a significant decrease in radiocapitellar contact pressures (p < 0.041). Valgus stability of specimens did not differ before and after shortening osteotomy (n.s.). The mean inclination angle (α) of the lesser sigmoid notch was 11.3° ± 6.3°. 46% had an inclination angle of ≤ 10° (type I). 46% had an inclination angle of 11°-20° (type II). In 8%, the inclination angle was >20° (type III).

Conclusion: Shortening osteotomy of the proximal radius can decrease radiocapitellar contact pressures during axial loading of up to 250 N. Primary valgus stability is not relevantly influenced by this procedure. In few patients, shortening osteotomy may cause radioulnar impingement of the radial head at the distal edge of the lesser sigmoid notch due to an inclination angle of >20°. Shortening osteotomy might be a promising treatment option to decrease pain levels in case of isolated radiocapitellar osteoarthritis.

Keywords: Biomechanics; Post-traumatic osteoarthritis; Proximal radius; Radial head fracture; Salvage procedure; Shortening osteotomy.