Summary
Objectives: To determine the sensitivity and specificity of arthroscopic estimation of positive
and negative radio-ulnar incongruence (RUI) in the canine elbow joint.
Methods: Experimental radial shortening and lengthening by 1 and 2 mm increments were performed
in nine right elbow joints, extending an established surgical in vitro model of RUI. Arthroscopic estimation of each artificially produced radio-ulnar joint
conformation (RUJC) was done using a graduated hook probe. A total of 72 RUJC were
blindly evaluated in a random manner by an independent investigator and estimated
in 1 mm increments (-2, -1, 0, +1, +2).
Results: The sensitivity for identification of an incongruent joint was 0.98 (95% CI: 0.90
to 0.99). The specificity for identification of a congruent joint was 0.89 (95% CI:
0.65 to 0.98). Analysing the data only in respect to a congruent joint versus one
with a shortened radius (positive RUI) resulted in a sensitivity of 0.96 (95% CI:
0.80 to 0.99) and a specificity of 1.00 (95% CI: 0.92 to 1.00).
Clinical significance: Accurate estimation of RUI in dogs affected by elbow dysplasia might improve functional
outcome and prevent osteoarthritis when corrective or modifying osteotomies are being
considered as part of the treatment plan. Arthroscopy has been shown to be highly
accurate and precise in detecting both positive and negative RUI in vitro. However, its diagnostic strength under clinical conditions still has to be proven.
Keywords
Elbow joint - arthroscopy - radio-ulnar incongruence - dog