Serial force plate analyses of dogs with unilateral knee instability, withor without interruption of the sensory input from the ipsilateral limb

Objective and Design: We characterized the mean peak vertical forces (MFz) in five group:; of dogs which underwent transection of the left anterior cr uciate ligament (ACLT) or sham ACLT and ipsilateral dorsal root ganglionect omy or sham-ganglionectomy, and the relationship of these forces to the sev erity of osteoarthritis (previously reported) 72 weeks after arthrotomy. Gr oup I (N=7) underwent ACLT; Group II (N=8) underwent ACLT followed 52 weeks later by ganglionectomy; Group III (N=7) underwent ganglionectomy followed 2 weeks later by ACLT; Group IV (N=7) underwent sham-ganglionectomy follow ed 2 weeks later by ACLT; Group V (N=8) underwent ganglionectomy followed 2 weeks later by sham-ACLT The dogs were evaluated 2, 6, 12, 24, 52 and 72 w eeks after arthrotomy. Results: From 6 weeks after arthrotomy until death, the left hindlimb MFz i n Group V was significantly greater (P<0.05) than that in the other four gr oups. The MFz of all groups which underwent ACLT decreased after arthrotomy . While the MFz of Group III (very severe OA) was about 10-20% greater than that of Groups I, II and IV (mild OA) 6 and 12 weeks after ACLT, and gener ally about 5-10% greater subsequently, this difference was not statisticall y significant. The MFz of Group IT returned to pre-ganglionectomy levels, r ather than to baseline levels, following ganglionectomy. Conclusions: (1) since the ipsilateral limb of dogs with ganglionectomy+sha m ACLT bore normal amounts of weight throughout most of the postsurgical pe riod, and its knee did not develop OA, one cannot argue that the knee was p rotected from OA because the limb was not used; (2) the fact that the MFz o f dogs which underwent ACLT+ganglionectomy returned to pre-ganglionectomy l evels, rather than baseline, is consistent with the hypothesis that the uns table joint was protected from accelerated breakdown by a central nervous s ystem that was reprogramed by sensation from the unstable limb; (3) the sli ghtly-but consistently-greater MFz of dogs which underwent ganglionectomy+A CLT may contribute to the acceleration of OA in this model. (C) 1999 OsteoA rthritis Research Society International.