Biomechanical Comparison of 4.0‐mm Short‐Threaded Cannulated Screws and 4.0‐mm Short‐Threaded Cancellous Screws in a Canine Humeral Condylar Fracture Model

Objective To compare biomechanical properties of a humeral condylar fracture model stabilized either with a 4.0‐mm short‐threaded cancellous screw ( CCS ) or with a 4.0‐mm short‐threaded cannulated screw ( CNS ). Study design In vitro biomechanical study. Sample Population Bilateral cadaveric canine humeri (n = 20). Methods Fractures of the lateral portion of the humeral condyle were simulated by standardized osteotomies; 10 condyles were each stabilized with CCS and 10 with CNS . Axial compression load was applied to each specimen until failure and force‐displacement curves generated. Testing data for each construct were determined and compared using either a Student's paired t‐test (quantitative data) or a χ 2 test (qualitative data) with statistical significance set at P < .05. Results Yield load (elastic limit), ultimate load at failure, and displacements at loads corresponding to walk and trot were determined from each curve. Mean ± SD ultimate load at failure was significantly higher ( P = .01) for CCS constructs (1261 ± 261 N) than for CNS constructs (1078 ± 231 N). Yield loads were not significantly different ( P = .10) between construct types, and exceeded all expected loads supported by the humeral condyle at walk. The risk of having a yield load below the expected physiologic load at trot was not statistically higher with a CNS construct compared with a CCS construct ( P = .26). Conclusion Humeral condylar fracture repaired either by a 4.0‐mm cannulated screw or a 4.0‐mm cancellous screw have comparable stability in this condylar fracture model.