A new canine cruciate ligament formed through distraction histogenesis. Report of a pilot study

A modified Ilizarov external fixator was used to transfix the stifle joint in 13 dogs. A 1-cm cortical cancellous bone plug was outlined in the intracondylar notch of the femur after excising the anterior (cranial) cruciate ligament (ACL). Hardware attached to the plug allowed controlled distraction of the plug into a cut tibial channel trailing the regenerate ligament. No attempt was made to exactly recreate the normal anatomic course of the ACL. Some bone plugs became dislodged from the femur before distraction began, while others consolidated prematurely. These specimens produced scar only and served as a control group against which the regenerate ligament and normal ACLs were contrasted biomechanically, biochemically, and histologically. The dogs were killed at intervals from four to 21 weeks postoperatively. Load to failure at 21 weeks reached 71% of the mean normal. Histologic examination showed an improved fiber organization of the regenerate compared with the scar group. The regenerate and scar groups showed increased percent water compared with normal, while there was no significant difference in percent collagen and glycosaminoglycan content.