Radiographic evaluation and comparison of the patellar ligament following tibial plateau leveling osteotomy and tibial tuberosity advancement in dogs: 106 cases (2009-2012).

OBJECTIVE To radiographically evaluate and compare changes in the patellar ligament of dogs following tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA). DESIGN Retrospective case series. ANIMALS 106 dogs that underwent TPLO (n = 59) or TTA (n = 47) for unilateral rupture of the cranial cruciate ligament at a private veterinary hospital from August 2009 through September 2012. PROCEDURES Medical records were reviewed to collect information on dog signalment, surgical procedure, whether arthrotomy had been performed, pre- and postoperative measurements of patellar ligament angle (PLA) and tibial plateau angle (TPA), and preoperative and follow-up measurements of patellar ligament thickness. RESULTS For dogs that underwent TTA, thickening of the distal portion of the patellar ligament was identified radiographically in 43 (92%) dogs at the first follow-up examination and 36 (77%) at the second follow-up examination. For dogs that underwent TPLO, these numbers were 57 (97%) and 54 (92%), respectively. A significant decrease in patellar ligament thickness was identified between the first and second follow-up examinations for TTA but not TPLO. Mean ± SD PLA following TTA was 89.46 ± 5.54°, representing a mean difference from the preoperative PLA of 11.86 ± 5.3°; following TPLO, mean TPA was 12.61 ± 4.03°, representing a mean difference from the preoperative TPA of 16.74 ± 7.13°. CONCLUSIONS AND CLINICAL RELEVANCE Patellar ligament thickening occurred following TPLO and TTA in dogs. The clinical relevance of this thickening remains unknown.

Inter- and intra-observer variability of radiography and computed tomography for evaluation of Zurich cementless acetabular cup placement ex vivo.

OBJECTIVE: To evaluate the inter- and intra-observer variability in measurement of the angle of lateral opening (ALO) and version angle measurement using digital radiography and computed tomography (CT). METHODS: Each hemipelvis was implanted with a cementless acetabular cup. Ventrodorsal and mediolateral radiographs were made of each pelvis, followed by CT imaging. After removal of the first cup, the pelves were implanted with an acetabular cup in the contralateral acetabulum and imaging was repeated. Three surgeons measured the ALO and version angles three times for each cup from the mediolateral radiographic projection. The same measurements were made using three-dimensional multiplanar reconstructions from CT images. Two anatomical axes were used to measure pelvic inclination in the sagittal plane, resulting in six measurements per cup. Two-way repeated measures analysis of variance evaluated inter- and intra-observer repeatability for radiographic and CT-based measurements. RESULTS: Version angle based on radiographic measurement did not differ within surgeons (p = 0.433), but differed between surgeons (p <0.001). Radiographic measurement of ALO differed within surgeons (p = 0.006) but not between surgeons (p = 0.989). The ALO and version angle measured on CT images did not differ with or between surgeons. CLINICAL SIGNIFICANCE: Assessment of inter- and intra-observer measurement of ALO and version angle was more reproducible using CT images than conventional mediolateral radiography for a Zurich cementless acetabular cup.