Measurement of the patellar tendon-tibial plateau angle and tuberosity advancement in dogs with cranial cruciate ligament rupture. Reliability of the common tangent and tibial plateau methods of measurement.

ABSTRACT

OBJECTIVES: To (i) compare agreement of the common tangent (CT) and tibial plateau angle (TP) methods in terms of measuring the patellar tendon angle (PTA) and required advancement and (ii) determine the intra- and inter-observer reliability of observers who measured PTA and the advancement. METHODS: Six observers were divided into three groups based on their level of experience. They measured the PTA and the required advancement on 43 radiographic images of the tibiae of dogs affected by cranial cruciate ligament rupture. Each observer repeated the measurements three times with each method. The inter-technique (interT), intra-observer (intraO), and interobserver (interO) reliabilities were evaluated, assessed by calculating the intraclass correlation coefficient (ICC), and represented by Jones plots. RESULTS: The agreement between PTA-CT and PTA-TP was low (the ICC interT values ranged from 0.11 to 0.4). The PTA-CT was associated with moderate intra-observer reliability (ICC intraO, CT = 0.61) and poor interobserver reliability (ICC interO, CT = 0.33). The PTA-TP was associated with good intra-observer reliability (ICC intraO, TP = 0.75) and moderate interobserver reliability (ICC interO, TP = 0.59). Interobserver reliability did not depend on the level of experience. The advancement measurements were associated with reliability results similar to those obtained for PTA. Jones' plots showed that the CT method consistently yielded lower PTA and advancement values than the TP method. CONCLUSION: Given its poor reliability, the CT method is not recommended.