The effect of post-fixation olecranon lengthening on range of motion of the elbow: a cadaveric study

BACKGROUND: Principles of fixation of comminuted olecranon fractures include anatomical reduction of the articular surface and restoration of ulnohumeral joint motion. However, comminution sometimes may not permit anatomical fixation of fracture fragments, resulting in inadvertent olecranon lengthening after plate fixation. The aim of our study is to investigate the relationship between olecranon lengthening following plate fixation and loss of elbow extension. MATERIALS AND METHODS: Transverse olecranon osteotomies were performed on 8 cadaveric elbows. The osteotomy sites were then fixed with olecranon plates. Lengthening of the osteotomy sites were simulated by placement of 2mm, 4mm, 6mm and 8mm blocks. Lateral view photographs of the elbows were taken after each degree of lengthening. These photographs were then printed and measurements of elbow extension were performed with a goniometer with average values taken. The measurements were tabulated and statistical analysis performed to determine the relationship between degree of elbow extension loss and amount of olecranon lengthening. RESULTS: Average values of each degree of lengthening (at 2mm, 4mm, 6mm and 8mm) were taken and compared with the baseline measurement (at 0mm). Cluster analysis showed that for every increment in osteotomy length of 2mm, there is a corresponding increase of 0.79° of elbow extension loss (p<0.01, 95% confidence level 0.55°-1.03°). CONCLUSION: Lengthening of olecranon by increments of 2mm correlates positively with loss of elbow extension. This shows that inadvertent intra-operative olecranon lengthening post-fixation may result in limited range of motion. However, it is reassuring to know that the small degree of extension loss may not translate to functional limitation.