Use of a collagen-platelet rich plasma scaffold to stimulate healing of a central defect in the canine ACL.

The anterior cruciate ligament (ACL) of the knee fails to heal after primary repair. Here we hypothesize that a beneficial biologic repair response can be induced by placing a collagen-platelet rich plasma (collagen-PRP) material into a central ACL defect. A collagen-PRP scaffold was used to treat a central ACL defect in vivo. In the first experiment, the histologic response in treated and untreated defects was evaluated at 3 (n = 5) and 6 weeks (n = 5). In the second experiment, biomechanical testing of the treated ligaments (n = 8) was performed at 6 weeks and compared with the results of biomechanical testing of untreated defects at the same time-point (n = 6). The percentage filling of the defects in the treated ACLs was significantly higher at both the 3- and 6-week time-points when compared with the untreated contralateral control defects (50 +/- 21% vs. 2 +/- 2% at 3 weeks, and 43 +/- 11% vs. 23 +/- 11 at 6 weeks; all values mean +/- SEM. Biomechanically, the treated ACL defects had a 40% increase in strength at 6 weeks, which was significantly higher than the 14% increase in strength previously reported for untreated defects (p < 0.02). Placement of a collagen-PRP bridging scaffold in a central ACL defect can stimulate healing of the ACL histologically and biomechanically.