In vivo comparison of two hinged transarticular external skeletal fixators for multiple ligamentous injuries of the canine stifle.

Controlled mobilization after the surgical repair of multiple disrupted ligaments is considered to be essential for return to normal function. This study compared the outcome after post-surgical mobilization without any protection to mobilization with two transarticular external skeletal fixator hinge prototypes after surgical repair of experimental injuries to multiple stifle ligaments in 15 hounds. The repair was left unprotected (NP: n=5), protected with a self-centering hinge (SH: n=5) and with a conventional hinge (CH: n=5) for four weeks after surgical repair. Outcome measurements included: orthopaedic examination, goniometric and thigh circumference (TC) measurements, total tibial translation (TT), radiographs, and kinetic gait analysis up to 120 days post-operatively. A significant effect of treatment controlling for time for medial collateral stability, TC, TT, osteophyte scores, peak vertical force (PVF) and vertical impulse (VI) was not found. There was a significant difference between time points for subjective lameness scores, TC, PVF, VI, TT and osteophyte scores within treatment. Stifle extension was significantly decreased in CH dogs compared to NP dogs on day 28. Stifle flexion was significantly decreased in CH and SH dogs on day 28 compared to NP dogs. Stifle flexion was normal in all dogs by day 42. Both hinges compromised stifle flexion initially after hinge removal, but range of motion normalized within two weeks. Hinges were not indicated for adjunct treatment after repair of multiple experimentally induced ligamentous stifle injuries.