Micro-CT Structural Analysis of the Canine Medial Coronoid Disease

To use micro-computed tomography (CT) to evaluate the fissure-fracture pattern in dogs affected by medial coronoid disease (MCD).

Prospective case-controlled study.

Client owned (n = 21) and cadaver dogs (n = 5).

Segments were excised by subtotal coronoid ostectomy from dogs with MCD. Two categories were identified: fissured (Fi) or fractured (F). Three subcategories were contingent on fissure-fracture orientation: tip (T), radial incisure (RI), and radial incisure encroaching tip (RIT). Control segments were from nondiseased cadavers. High-resolution micro-CT (3 dimensional and 2 dimensional) was performed on all segments. Measurements included mean bone mineral density, trabecular number and thickness, and the angle of the fissure-fracture relative to the predominant trabecular orientation.

A total of 28 diseased segments from 21 dogs (mean age 23.3 months, mean bodyweight 31.5 kg) were analyzed and categorized according to fissure-fragment location as Fi-T (n = 2), Fi-RIT (n = 2), Fi-RI (n = 3), F-T (n = 5), F-RIT (n = 9), F-RI (n = 7). The 3D analysis revealed subchondral micro-fracturing occurred in association with fragmentation. Canalicular impaction was associated with increase in trabecular number and decrease in trabecular space, most notably in RI categories. The 2D analysis showed that predominant trabecular orientation in control segments was significantly different to RI but not to T. The mean (SD) angle difference between the orientation of fissure-fracture and the predominant trabecular pattern was 6.9 (6.9)° for RI and 44.6 (49.6) ° for T.

T and RI fissure-fracture patterns show morphologic differences and likely arise from different supraphysiologic loading. Medial compartment disease is not homogenous and pattern recognition may assist further investigation of etiopathogenesis.