A mismatch of planning and achieved tibial plateau angle in cranial closing wedge surgery: An in silico and clinical evaluation of 100 cases.

OBJECTIVE: (1) To determine whether Oxley's modified cranial closing wedge osteotomy (CCWO) results in a tibial plateau angle (TPA) of 5° in silico, (2) compare in silico to clinical postoperative TPA and (3) determine the impact of ostectomy distalization in silico. STUDY DESIGN: Cross-sectional retrospective radiographic in silico study. SAMPLE POPULATION: A total of 100 stifle radiographs; 90 dogs (small ≤25 kg = 84; large >25 kg = 16). METHODS: Tibial plateau angles were measured preoperatively (TPAPre ), after in silico planning (TPAPlan ), and postoperatively (TPAPost ). Virtual ostectomies were evaluated for plate fit. Postoperative ostectomy position was measured. Virtual ostectomies were performed 5/7.5/10/15 mm from the patellar tendon insertion in 10 dogs from each preoperative TPA category (≤20°/21-25°/ 26-30°/31-35°/>35°). Comparisons for TPAPre , TPAPost , and TPAPlan were made between small and large dogs, and the outcome to the target 5° between TPA categories and ostectomy positions. RESULTS: Mean ± SD TPAPre was 28.6 ± 6.2° and higher in small than large dogs. Mean TPAPlan was 7.6 ± 2.7°. Plate fit was appropriate in all. In silico, TPAs were greater than 5° except for cases with TPAPre > 35°. Median TPAPost was 5.5° (-4-21) and was higher in small (7°) than large (4.5°) dogs. Postoperative ostectomy position was more distal than Oxley's guidelines. When distalized >7.5 mm in silico, the magnitude of under-correction increased. CONCLUSIONS: Oxley's modified CCWO did not result in TPA of 5° in most cases. Ostectomy distalization exacerbated under-correction. CLINICAL IMPACT: Current guidelines should be modified to achieve 5° TPA postoperatively.

Influence of extreme brachycephalic conformation on perioperative complications associated with total ear canal ablation and lateral bulla osteotomy in 242 dogs (2010-2020).

OBJECTIVE: To determine the influence of extreme brachycephalic conformation on presenting signs, imaging findings, intraoperative and perioperative complications following total ear canal ablation and lateral bulla osteotomy (TECA-LBO). STUDY DESIGN: Cross-sectional retrospective study. ANIMALS: A total of 306 (n = 242 dogs) TECA-LBOs (extreme brachycephalic breeds [EBB] = 81, other breeds [OB] = 225). METHODS: Medical records of patients undergoing TECA-LBO at a single referral institution (2010-2022) were evaluated. RESULTS: Extreme brachycephalic breeds most commonly presented acutely, at a younger age with oto-neurological signs (46/81, 56.8%). Chronic otitis externa without neurological signs (171/225, 76.0%) was most common in OBs. Extreme brachycephalic breeds preoperatively presented more frequently with facial nerve paresis (p = .001), vestibular syndrome (p = .001), and Horner's syndrome (p = .002) compared to OBs. On diagnostic imaging, bilateral changes (p = .038), aural masses (p = .045), para-aural abscesses (p = .011), otitis interna (p = .001), and brainstem changes (p = .001) were more common in EBBs. The apparent difference in intraoperative complication rate between EBBs (9/81, 11.1%) and OBs (12/225, 5.3%) did not reach statistical significance (p = .078). Perioperative complications occurred in 85/306 (27.8%) of TECA-LBOs with no difference in perioperative complication rate between EBBs (19/81, 23.5%) and OBs (66/225, 29.3%) (p = .586). CONCLUSION: Extreme brachycephalic breeds are more likely to present for TECA-LBO acutely, with neurological signs and more advanced diagnostic imaging abnormalities. Intra- and perioperative complication rates did not differ between EBBs and OBs. CLINICAL SIGNIFICANCE: Despite being subjectively more technically challenging, TECA-LBO did not result in more surgical complications in EBBs. Reported data are useful for effectively informing clients of the specific risks of TECA-LBO surgery.

Establishment of Normal Mechanical Tibial Joint Angles in Dachshunds.

OBJECTIVE: The aim of this study was to establish breed-standard mechanical tibial joint reference angles in the frontal plane in Dachshunds. STUDY DESIGN: Craniocaudal (n = 38) and mediolateral (n = 32) radiographs of normal tibiae from Dachshunds were retrospectively reviewed. The mechanical medial proximal, mechanical medial distal, mechanical caudal proximal and mechanical cranial distal tibial angles were measured on three occasions by two separate observers using previously established methodology. Interclass correlation coefficient was used to assess the reliability of radiographic measurements. RESULTS: The mean and standard deviation for mechanical medial proximal, mechanical medial distal, mechanical caudal proximal and mechanical cranial distal were 93.1 degrees ± 4.2, 97.5 degrees ± 3.9, 75.3 degrees ± 3.7 and 85.0 degrees ± 5.3 respectively. Intra-observer reliability was good to excellent for all measures, while inter-observer reliability was moderate to excellent in the frontal plane and poor to good in the sagittal plane. Dachshund-specific joint reference angles were similar to a range of previously reported non-chondrodystrophic breeds in the frontal plane but differed to most in the sagittal plane. CONCLUSION: Dachshund tibial joint reference angles are reported which can be used in surgical planning for correction of bilateral pes varus.