The Effect of Buttress Plating on Biomechanical Stability of Coronal Shear Fractures of the Capitellum: A Cadaveric Study.

Purpose: The purpose of this study was to compare, using a cadaveric model, the biomechanical properties of headless compression screws (HCSs) and HCSs augmented with a buttress plate (BP) in capitellar fractures.

Methods: Twenty pairs of fresh-frozen humeri (mean age, 46.3 years; range, 33-58 years) were used. The soft tissue was removed, and a Dubberley type IA capitellar fracture was created. One specimen in each pair was randomly assigned to receive either two 2.5-mm HCSs (HCS group) or two 2.5-mm HCSs augmented with an anterior 2.4-mm BP (HCS + BP group). This resulted in a similar distribution of the left and right humeri between the groups. Cyclic loading was performed, and displacement of the capitellum at 50, 100, 250, 500, 1,000, and 2,000 cycles was assessed using a motion capture system. This was followed by load-to-failure testing, wherein the load at a displacement of 1 and 2 mm was recorded. Failure was defined as 2-mm displacement.

Results: During cyclic loading, there were no significant differences in the displacement between the HCS and HCS + BP groups at any of the assessed cycles. During load-to-failure testing, no significant strength differences were observed in the load at 1-mm displacement between the HCS (mean: 449.8 N, 95% CI: 283.6-616.0) and HCS + BP groups (mean: 606.2 N, 95% CI: 476.4-736.0). However, a significantly smaller load resulted in a 2-mm displacement of the fragment in the HCS group (mean: 668.8 N, 95% CI: 414.3-923.2) compared with the HCS + BP group (mean: 977.5 N, 95% CI: 794.1-1,161.0).

Conclusions: Anterior, low-profile buttress plating in addition to HCSs results in a significantly higher load to failure compared with HCSs alone in a biomechanical Dubberley type IA capitellar fracture model.

Clinical Relevance: The addition of an anterior BP may be considered to improve initial stability in select cases such as osteoporotic patients or when the posterolateral column is frail.