Computed Tomographic Assessment of Block Recession Trochleoplasty and Partial Parasagittal Patellectomy in Cats.

OBJECTIVE: The aim of this study was to assess computed tomography (CT) images of cadaveric feline stifles and record the relationship between the patella and femoral trochlea in normal stifles; then to investigate the effect of block recession trochleoplasty (BRT) with and without partial parasagittal patellectomy (PPP) on patellofemoral contact, depth of patellar recession and size of trochlea and patella. MATERIALS AND METHODS: The sample population included six cat cadavers (12 stifles). Preoperative CT scans with stifles in three positions: extended (155-165°), neutral (85-95°) and flexed (35-45°). Lateral stifle arthrotomy was followed by BRT. CT scans were taken as above. PPP was performed so the width of the patella was 1 mm narrower than the BRT. CT scans were repeated and CT measurements were taken. RESULTS: The area of contact between the patella and femoral trochlea was significantly reduced after BRT and then significantly increased after PPP. The depth of patellar recession was unchanged after BRT, but then was significantly higher after PPP. The patella was wider than the trochlea preoperatively and post-BRT and narrower post-PPP. Reduction in bone volume following PPP (mean: 20%) was 50% the reduction in patella width (mean: 40%). CONCLUSION: Block recession trochleoplasty did not improve patellar recession and decreased patellofemoral contact area. Following BRT, the patella rides the trochlear ridges and loses contact with the trochlear sulcus. Block recession trochleoplasty alone should not be performed in cats. Instead, BRT should be combined with PPP.

Combined physeal fractures of the distal radius and ulna: complications associated with K-wire fixation and long-term prognosis in six cats.

Objectives The objective was to describe the complications and long-term outcome associated with Kirschner (K)-wire fixation of combined distal radial and ulnar physeal fractures in six cats. Methods Medical records (2002-2014) of six referral institutions were searched for cats with combined distal radial and ulnar physeal fractures. Cases with complete clinical files, radiographs and surgical records were retrospectively reviewed. Long-term outcome was assessed via telephone interviews using an owner questionnaire. Results Complete files were available for 6/9 identified cases (cases 1-6). All fractures were classified as Salter-Harris type I or II. Five cases underwent open reduction and internal fixation via cross-pinning of the distal radius and intramedullary pinning of the ulna (cases 1-3); fixation of the distal radial and ulnar physes with one K-wire each (case 4); and K-wire fixation of the radial physis in combination with two transulnoradial K-wires (case 5). One case underwent closed reduction and percutaneous cross-pinning of the distal radius under fluoroscopic guidance (case 6). The complications encountered were: reduced radiocarpal range of motion (ROM) (cases 1, 3, 4, 5); implant loosening/migration (cases 1, 2, 5); and radioulnar synostosis (case 4). None of the cats developed angular limb deformity. Long-term outcome (12 months to 7 years after surgery) was graded as 'excellent' by the owners in all cases. Conclusions and relevance Prognosis is favourable for feline combined distal radial and ulnar physeal fractures following K-wire fixation in cats over 7 months of age. Implant removal after bony union is recommended to minimise reduction in ROM and to prevent implant loosening/migration.

Can a surgeon drill accurately at a specified angle?

OBJECTIVES: To investigate whether a surgeon can drill accurately a specified angle and whether surgeon experience, task repetition, drill bit size and perceived difficulty influence drilling angle accuracy. METHODS: The sample population consisted of final-year students (n=25), non-specialist veterinarians (n=22) and board-certified orthopaedic surgeons (n=8). Each participant drilled a hole twice in a horizontal oak plank at 30°, 45°, 60°, 80°, 85° and 90° angles with either a 2.5  or a 3.5 mm drill bit. Participants then rated the perceived difficulty to drill each angle. The true angle of each hole was measured using a digital goniometer. RESULTS: Greater drilling accuracy was achieved at angles closer to 90°. An error of ≤±4° was achieved by 84.5 per cent of participants drilling a 90° angle compared with approximately 20 per cent of participants drilling a 30-45° angle. There was no effect of surgeon experience, task repetition or drill bit size on the mean error for intended versus achieved angle. Increased perception of difficulty was associated with the more acute angles and decreased accuracy, but not experience level. CLINICAL SIGNIFICANCE: This study shows that surgeon ability to drill accurately (within ±4° error) is limited, particularly at angles ≤60°. In situations where drill angle is critical, use of computer-assisted navigation or custom-made drill guides may be preferable.

Imaging diagnosis--extrahepatic biliary tract obstruction secondary to a biliary foreign body in a cat.

An 11-year-old, neutered female British Shorthair cat was referred with a 4-week history of abdominal pain and vomiting. Abdominal ultrasonography revealed a dilated common bile duct containing a spindle-shaped structure with several reflecting interfaces. Differentials that were considered included an intraluminal foreign body, or helminth parasites within the common bile duct. Surgical exploration of the abdominal cavity demonstrated the presence of two grass awns obstructing the common bile duct. Anomalies of the portal vasculature were noted during surgery and were considered an incidental finding. The clinical signs resolved following surgical removal of the grass awns.