CTassessment of the influence of dynamic loading on physiological incongruency of the canine elbow

Abstract

Significant changes in humero-radio-ulnar congruency occurred suggesting pronation of the radius with respect to the ulna was induced during loading. This movement may influence the load experienced by the medial coronoid process and could play a role in the aetiopathogenesis of medial coronoid process disease.

Topographic Bone Density of the Radius and Ulna in Greyhounds and Labrador Retrievers With and Without Medial Coronoid Process Disease

“…Anecdotally, we have also noted on CT that sclerosis appears to affect the radial head in dogs with MCPD; however, this observation is yet to be quantified. Quantification of bone density in the radial head may provide novel information on the pathogenesis of MCPD, supporting a recent ex vivo study documenting rotational abutment of the radial head against the MCP as a function of elbow load …”

“…Initial theories proposing a primary osteochondrosis lesion have been more recently refuted by the theory of supraphysiological loading because of radioulnar axial length mismatch, resulting in subchondral microfracture and subsequent overt fissure formation . Multiple incongruities have been postulated including: trochlear notch deformity, humeroulnar incongruity, radioulnar incongruity, and a primary rotational incongruity, either as a compressive force of the coronoid against the humeral condyle because of the pull of the biceps brachialis muscle or rotation of the radial head against the apex of the medial coronoid process (MCP) . This latter study suggests the radial head may play a primary role in the formation of MCPD.…”

CT evaluation of elbow congruity in dogs: radial incisure versus apical medial coronoid process fragmentation

“…We consider that a reduction in joint space at this point could evoke a pivot point within the radioulnar articulation such that if rotation of the radius against the ulna were to occur during stance (Burton et al . , Rohwedder et al . ) it would cause focal overload in the region of the radial incisure, resulting in osteochondral fragmentation at this site (Fig ).…”

“…, Burton et al . ). However, fluoroscopic kinematography has recently refuted variance in axial dynamic congruity between normal and dysplastic elbows as an inciting cause of MCPD (Rohwedder et al .…”

Radial torsion in dogs with medial compartment disease

“…Although historically an axial overload of the MCP has been described as a cause of fragmented MCP (FMCP), other theories have recently challenged that mechanism as a cause of the FMCP . These alternative theories include overload caused by dynamic axial or rotational incongruity between the humerus, the radius, and ulna, or ligamentous instability across the joint . Fitzpatrick et al and others proposed that torsional overload during pronation and supination along with osseous incongruity in the transverse plain could be responsible for the pathology noted at the radial incisure.…”