SummaryThe purpose of this study was to evaluate the use of three dimensional imaging techniques in veterinary orthopaedic surgery to measure hip congruity and predict changes in congruity resulting from triple pelvic osteotomies of canine hips. Preoperative, postoperative, and post-simulation measurements of congruity were obtained from eight canine hips by determination of Norberg angles from ventrodorsal pelvic radiographs (1), and lateral centre-edge (CE) angles from three dimensional (3 D) reconstructions of computed tomography (CT) scan data (2). Half of the hips were treated with a triple pelvic osteotomy with 30 degrees of axial rotation, and the other half served as approached but unoperated controls. Each measurement was performed three times by a single evaluator blinded to the identity of each hip. Lateral centre-edge angle measurements were more precise than Norberg angle measurements as determined by the calculated measurement of reliability (R = 0.78 and 0.68 respectively). Triple pelvic osteotomy resulted in an increase in congruity (as measured by lateral CE angles) of 52.2 ± 4.6 degrees compared to -3.0 ± 6.3 degrees in the control hips. The medical imaging programme used to perform the 3D reconstructions from CT scan data also allowed manipulation of the resulting preoperative 3D images to simulate on the computer screen the triple pelvic osteotomies performed on the gross specimens. Surgical procedure simulation predicted the change in congruity (as measured by lateral CE angles) of operated hips to be 43.5 ± 8.8 degrees. The images obtained by 3D reconstruction were very sensitive indicators of gross hip morphology. Visualization of structures, superimposed or surrounded by bone, was easily performed on the computer by interactive manipulation of the three dimensional CT scan reconstructions. In addition to its unique imaging capabilities, this technique appears to be a useful method for non-invasive measurement and prediction of the effects of triple pelvic osteotomy on hip congruity in dogs.Three dimensional (3D) computer aided image reconstructions were performed on tomographic scan data collected from dysplastic canine pelves before and after triple pelvic osteotomy (TPO). Descriptions of imaging capabilities and the application of lateral centre-edge angles for the determination of hip congruity are reported. Simulations performed on the computer accurately predicted the changes in congruity achieved by surgery.

The occurrence of primary endotracheal adenocarcinoma in two 12-year-old cats is reported. Dyspnoea was the most dominant clinical sign in both cases. The endotracheal masses were identified radiographically and removed via thoracotomy and tracheotomy in the first case and cervical tracheal resection and anastomosis in the second case. In both cases, the diagnosis of adenocarcinoma was confirmed histopathologically.

To reduce postoperative complications due to pelvic canal narrowing following triple pelvic osteotomy, it is important to minimize the length of the pubic remnant on the acetabular segment. Three different techniques for performing the pubic osteotomy were compared: a lateral wire saw technique, a lateral osteotome technique and a ventral osteotome ostectomy technique. The lateral wire saw and ventral ostectomy techniques resulted in significantly shorter public remnants than the lateral osteotome technique. The osteotomies performed with the wire saw were more accurate and precise than those performed with the osteotome. The lateral wire saw technique is a practical alternative to the ventral ostectomy technique for performing the pubic osteotomy.

SummaryThirteen pairs of tibiae were excised from adult mongrel dogs following a mean recovery period of 24.2 weeks after unilateral total hip arthroplasty (THA). Prior to euthanasia, peak vertical dynamic load, as a percent of body weight, was determined for each limb at a walking pace. Four contiguous proximal sections and one transverse cortical midshaft section, 5mm thick, were harvested from each tibia. Contact Faxitron radiographs of the sections were quantified, using video digitizing software, to compare mean apparent density measures between the treated (THA) and intact limbs. There was a significant difference in mean apparent density of cancellous bone with the treated limb having a lower apparent density than the intact limb. The mean cortical area at the midshaft was significantly lower and the medullary area significantly higher among tibiae from the treated side, as compared to the contra-lateral tibiae. Resistance to bending and tension at the midshaft of each bone were determined using the second moment of area about cranio-caudal (Ix) and mediolateral (Iy) axes. The mean Iy values for the treated limbs were significantly lower than for the intact limbs. Therefore, measurable adaptive bone remodeling appears to be present in both cancellous and cortical bone in the tibia due to decreased mechanical loading.

In a series of twenty-two cats with femoral fractures repaired by internal fixation, four cases of quadriceps contracture (18.2%) were observed. Each case of contracture involved a midshaft fracture with extensive soft tissue injury. Repair with intramedullary pins and cerclage wires had been performed in each case. Exuberant callus production was noted in two cases, while in another quadriceps contracture followed injury to the ischiatic nerve. Contracture was evident two weeks postoperatively. Physiotherapy proved ineffective and surgical intervention was not undertaken as all cases were weightbearing on the affected limb.