Three-Dimensional Joint Kinematics in a Canine Elbow Joint with Medial Coronoid Disease before and after Bi-Oblique Dynamic Proximal Ulnar Osteotomy

Abstract Objective The aim of this study was to report the humeroulnar joint kinematics in a dog with medial coronoid process disease (MCPD) before and after dynamic proximal ulnar osteotomy (DPUO). Study Design A 15-month-old female Labrador Retriever with advanced MCPD was treated by DPUO and fragment removal. Bi-planar fluoroscopic kinematography of the affected joint was performed before and 12 weeks after DPUO along with computed tomography. Static axial radioulnar incongruence (sRUI), dynamic relative proximodistal radioulnar motion (dynamic RUI), axial humeroulnar rotation, as well as humeroulnar joint contact at the medial coronoid process (MCP) were calculated. Results Static axial radioulnar incongruence was reduced from 2.3 to 1.5 mm after DPUO but dynamic RUI remained unchanged (0.2 vs. 0.3 mm). Mean humeroulnar rotational amplitude increased from 2.6° (standard deviation 0.4) to 4.5° (standard deviation 2.0). Joint contact area at the MCP became substantially increased as well as broadly distributed among the MCP following DPUO (52.5 vs. 63.0%; p = 0.0012). Conclusion Dynamic proximal ulnar osteotomy failed to restore the radioulnar congruence and increased the humeroulnar rotational instability. No effect was observed on dynamic RUI. Nevertheless, joint contact area at the MCP was increased and became more homogeneously distributed, which might explain the beneficial effect of clinical outcome in this case.