Abstract
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.
Highlights
No effect was observed on dynamic RUI
Joint contact area at the medial coronoid process (MCP) was increased and became more homogeneously distributed, which might explain the beneficial effect of clinical outcome in this case
Other factors, which have been cited as a potential biomechanical cause of medial coronoid process disease (MCPD), are dynamic RUI and humeroulnar rotational instability.[10,11,12,13,14,15,16]
Summary
Developmental elbow disease is a common cause of forelimb lameness especially in young dogs, being bilateral in 25 to 80% of cases.[1,2,3,4,5] A permanent developmental mismatch in the radioulnar joint surface, called static axial radioulnar incongruence (sRUI), has been shown to increase load at the medial coronoid process (MCP).[6,7] Being related to the severity of joint pathology at the medial joint compartment,[8] sRUI is commonly cited as one factor for the development of medial coronoid process disease (MCPD).[3,9] Other factors, which have been cited as a potential biomechanical cause of MCPD, are dynamic RUI (dRUI) and humeroulnar rotational instability.[10,11,12,13,14,15,16] Dynamic RUI is defined as an increased motion between the radius and ulna, leading to a temporary incongruence of the radioulnar joint surface during locomotion. SRUI as well as dRUI have recently been excluded as primary causes of MCPD.[10,17,18]
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