Plate vs. intramedullary screw fixation of chevron olecranon osteotomies: a biomechanical study.

BACKGROUND

Intra-articular distal humerus fractures frequently require olecranon osteotomies for adequate exposure, but fixation of olecranon osteotomies is associated with high rates of hardware-related complications requiring subsequent reoperation for removal. Intramedullary screw fixation is an attractive option to attempt to minimize hardware prominence. The purpose of this biomechanical study is to directly compare intramedullary screw fixation (IMSF) with plate fixation (PF) of chevron olecranon osteotomies. It was hypothesized that PF would be biomechanically superior to IMSF.

METHODS

Chevron olecranon osteotomies of 12 matched pairs of fresh-frozen human cadaveric elbows were repaired with either precontoured proximal ulna locking plates or cannulated screws with a washer. Displacement and amplitude of displacement at the dorsal and medial aspects of the osteotomies under cyclic loading conditions were measured. Finally, the specimens were loaded to failure.

RESULTS

The IMSF group had significantly greater medial displacement (P = .034) and dorsal amplitude (P = .029) than the PF group. Medial displacement was negatively correlated with bone mineral density in the IMSF group (r = -0.66, P = .035) but not in the PF group (r = .160, P = .64). Mean load to failure between groups, however, was not statistically significant (P = .183).

CONCLUSIONS

While there was no statistically significant difference in the load to failure between the two groups, IMSF repair resulted in significantly greater displacement of the medial osteotomy site during cyclic loading and greater amplitude of displacement dorsally with loading force. Decreased bone mineral density was associated with an increased displacement of the medial repair site. These results suggest that IMSF of olecranon osteotomies may result in increased fracture site displacement when compared to PF; this displacement may be greater in patients with poor bone quality.