Arthroscopic Assessment of Trochlear Groove Depth in the Canine Stifle. Hudson C, Coleman K, Kim W, Black T. Gulf Coast Veterinary Specialists, Houston, TX.
Dogs with medial patellar luxation (MPL) commonly have a shallow trochlear groove. To date, no objective method for assessing trochlear groove depth (TGD) during stifle arthroscopy has been described. We hypothesized that arthroscopic measurement of TGD is feasible and no significant differences would be identified between actual and arthroscopically measured TGD. Arthroscopy was performed on 16 canine cadaver stifles. A measuring rod was inserted percutaneously from cranial to caudal into the patellofemoral joint and used to measure TGD (aTGD) sequentially by two observers. Femurs were dissected, and actual TGD was measured using a caliper (cTGD). A significant difference was identified between mean aTGD (2.71 ± 0.50 mm) and cTGD (2.57 ± 0.49 mm) measurements. Bland-Altman plot analysis of aTGD versus cTGD revealed evidence of a −0.13 mm bias and 95% limits of agreement within 0.24 mm of the mean. Our hypothesis was partially accepted as aTGD measurement was feasible in cadaver stifles but resulted in slight overestimation of the depth of the trochlear groove (0.13 mm on average). The discrepancy between aTGD and cTGD measurements would represent an average error of ∼ 2% in TGD assessment which would be unlikely to affect clinical decision making. This cadaver study was performed in a small number of normal stifles and the technique may prove difficult to translate into clinical patients with MPL. The authors conclude that the described arthroscopic technique is accurate enough to provide meaningful decision-making information regarding TGD.