May a Single Presurgical High-Field MRI Sequence Replace Standard Radiographs for TPLO Surgical Planning in Dogs?

Cranial cruciate ligament (CCL) disease causes variable stifle instability assessed by specific clinical tests. Radiographs are performed to measure the tibial plateau angle (TPA) for planning tibial plateau leveling osteotomy (TPLO) surgery. Concomitant damage to other intra-articular structures, for which clinical detection is unreliable, may occur and potentially affect the surgical outcome. Joint assessment during TPLO through instrumented inspection is therefore advised, though it increases the risk of complications. Magnetic resonance imaging offers a noninvasive alternative, adds information about intra- and periarticular structures, and could potentially be used for TPA measurements. This prospective study aimed to (1) assess the correlation between the TPA measured with the standard presurgical radiographs and with a single sagittal intermediate-weighted fat-saturated MRI sequence and (2) compare the surgical findings with the information obtained by the MRI sequence. Twenty-one stifles were included; TPA correlation using radiographs-MRI was available for 17 stifles, and surgery-MRI comparison was available for 18 stifles. A strong significant correlation was identified between the TPA measurements on radiographs-MRI (Pearson correlation coefficient 0.923; p-value <.0001). The sensitivity and specificity of MRI to detect surgically confirmed complete versus partial CCL rupture were 85.7% and 75%, respectively; MRI identified 7 of 8 surgically confirmed injured menisci and detected abnormal signal intensity in 8 of 10 medial menisci and nine caudal cruciate ligaments reported as normal intra-operatively. The MRI additionally identified abnormal subchondral bone signals in nine stifles and muscular hyperintensity in six cases. This presurgical MRI sequence might replace standard radiographs for TPA measurements and can provide information about concomitant joint injuries with potential prognostic impact.