Radiographic Quantitative Assessment of Caudal Proximal Tibial Angulation in 100 Dogs with Cranial Cruciate Ligament Rupture

Objective: To evaluate inter- and intraobserver variability in the measurement of distal tibial axis/proximal tibial axis angle (DPA) from lateral radiographs of canine tibia in dogs with cranial cruciate ligament rupture (CCLR). Study Design: Retrospective clinical study. Animals: Dogs (n = 100) with cranial cruciate ligament rupture. Methods: Medical records of dogs diagnosed with CCLR were reviewed. In addition to signalment and TPA measurements, measured DPA (mDPA) was calculated for each lateral view of the tibia in each animal, twice, by 3 blinded observers. Subjective scoring of DPA (sDPA) was also recorded, twice, by 3 additional blinded observers from lateral views of the proximal half of the tibia in each dog. Inter- and intraobserver variability was measured by intraclass correlation coefficient (ICC) for each measurement. Correlation between mDPA and sDPA was also determined. Results: Median tibial plateau angle (TPA) of the subject population was 27.9 degrees (range 18.8-41.3 degrees; IQR: 25.5-30.75 degrees). Mean +/- SD mDPA was 6.50 +/- 2.81 degrees (confidence intervals [CI]: 5.94-7.06 degrees; range 0-13.33 degrees). There was no correlation between age and weight of dogs and the mDPA (P = .58 and .12). There was a moderate correlation between mDPA and TPA (r(2) = 0.49, P < .0001). There was a moderate correlation between sDPA and mDPA (r(2) = 0.27, P < .0001). Good inter- and intraobserver agreement was found in the measurement of mDPA. Conclusion: mDPA is a reproducible measurement of caudal angulation of proximal tibia. Furthermore, mDPA of dogs with cranial cruciate ligament disease in this report are in concordance with previous reports.