Ex vivo kinematic studies of a canine unlinked semi-constrained hybrid total elbow arthroplasty system.

OBJECTIVES: Introduction of the Sirius® canine total elbow arthroplasty system, and presentation of the results of a passive range-of-motion analysis based on ex vivo kinematic studies pre-and post-implantation. MATERIALS AND METHODS: Thoracic limbs (n = 4) of medium sized dogs were harvested by forequarter amputation. Plain orthogonal radiographs of each limb were obtained pre- and post-implantation. Limbs were prepared by placement of external fixator pins and Kirschner wires into the humerus and radius. Each limb was secured into a custom-made box frame and retro-reflective markers were placed on the exposed ends of the pins and wires. Each elbow was manually moved through five ranges-of-motion manoeuvres. Data collected included six trials of i) full extension to full flexion and ii) pronation and supination in 90° flexion; a three-dimensional motion capture system was used to collect and analyse the data. The Sirius elbow prosthesis was subsequently implanted and the same measurements were repeated. Data sets were tested for normality. Paired t-tests were used for comparison of pre- and post-implantation motion parameters. RESULTS: Kinematic analysis showed that the range-of-motion (mean and SD) for flexion and extension pre-implantation was 115° ± 6 (range: 25° to 140°). The range-of-motion in the sagittal plane post-implantation was 90° ± 4 (range: 36° to 130°) and this reduction was significant (p = 0.0001). The ranges-of-motion (mean and SD) for supination and pronation at 90° were 50° ± 5, whereas the corresponding mean ranges-of-motion post-implantation were 38° ± 6 (p = 0.0188). CONCLUSION: Compared to a normal elbow, the range-of-motion was reduced. Post-implantation, supination and pronation range-of-motion was significantly reduced at 90° over pre-implantation values. CLINICAL RELEVANCE: These results provide valuable information regarding the effect of the Sirius system on ex vivo kinematics of the normal canine elbow joint. Further, this particular ex vivo model allowed for satisfactory and repeatable kinematic analysis.

Patellar ligament rupture in the dog: repair methods and patient outcomes in 43 cases.

The medical records of dogs receiving surgery for unilateral patellar ligament rupture between 1999 and 2012 at 12 multidisciplinary referral centres were reviewed. Forty-three cases were identified; 26 were traumatic in origin; almost one-third were iatrogenic, of which over three-quarters occurred as a complication following surgical stabilisation of patellar luxation. Treatment involved primary reapposition of the ligament (36 cases). The repair was protected by circumpatellar and/or transpatellar loop(s) of orthopaedic wire, nylon, polypropylene or polydioxanone suture (34 cases). Wire loops were more likely to require surgical removal compared with loops of other materials (P=0.0014). The stifle joint was immobilised postoperatively by the applications of a transarticular external skeletal fixator (taESF) in 17 cases and by external coaptation (EC) in 8 cases; in 18 cases, no postoperative joint immobilisation was provided. Complications specific to the method of immobilisation occurred in seven of the cases with taESF and six of the cases with EC. Revision surgery to address failure of repair was required in five cases. Outcome was classified as acceptable or good in over three-quarters of the cases (31/40) and poor in less than a quarter (9/40). These data highlight patellar ligament rupture as a complication of surgical stabilisation of patellar luxation.

Cranial tibial plating in the management of failed tibial tuberosity advancement in four large breed dogs.

The management of failed surgical procedures involving osteotomy for tibial tuberosity advancement can be demanding due to the limited available bone stock, which must be large enough to counteract the powerful proximal and cranial distractive forces exerted by the quadriceps mechanism. Initial mode of failure may be related to implant failure, fracture of the tibial tuberosity, or a combination of both. The complications and management of the cases reported here were all associated with avulsion fracture of the tibial tuberosity following tibial tuberosity advancement. In all cases, a cranial tibial dynamic compression plate was applied to reduce the fractures and stabilize the osteotomy. No further major complications associated with the implants or fracture occurred. Radiographic evidence of progression of fracture healing was documented in all four cases at the six to eight-week postoperative follow-up. Long-term follow-up information was available for three out of four cases at nine to 23 months after surgery by telephone interview and validated owner questionnaires. Owners reported return to normal exercise with intermittent lameness occurring in two of the three cases. The authors concluded that this technique offers an alternative technique for the management of such fractures, in particular in large breed dogs where sufficient tibial tuberosity bone stock remains.