Meeting Abstract
83.6 Friday, Jan. 7 How a quadruped limps: long-term quantification of support redistribution following injury in the dog BERTRAM, JEA*; GUTMANN, A; GERMSCHEID, N; MATYAS, J; Univ. of Calgary, Calgary, Canada jbertram@ucalgary.ca
During locomotion, terrestrial mammals must support body weight as they propel themselves forward. If one limb is unable to support the normal proportion of weight, support must be redistributed to the other limbs. In a biped there is only one option, so it is straightforward to document the redistribution that occurs as a result of injury and over the course of recovery. Quantifying the redistribution of support in a quadruped is much more complex, as many more options exist and multiple limbs can provide support simultaneously. We report weekly individual limb support over a two year period for dogs with unilateral anterior cruciate ligament transection (participating in a study of osteoarthritic joint degeneration). We used a serial force platform system with four individual sensors and analyzed the impulse ratio, the proportion of the total support impulse over a stride contributed by each of the four limbs. This allowed the use of trials in which the animals trotted at a range of speeds and accelerations, greatly facilitating the collection of data compared with traditional force platform analyses (where speed and acceleration must be rigidly controlled). The data indicate an initial profound effect on the proportion of load supported by the affected limb followed by a gradual recovery that continued for over 300 days, eventually resulting in a modest but persistent redistribution of support load. Support redistribution was almost exclusively to the affected limb’s contralateral partner, with little or no redistribution between fore and hind limbs. Although these conclusions cannot currently be extrapolated to bilateral pathologies or to mammals with a less cursorial movement pattern (such as rodents), the results indicate that the impulse ratio can be applied as a meaningful and convenient method of quantifying support redistribution in quadrupeds.
