Purpose: ACL injury is a risk factor for early post-traumatic osteoarthritis (PTOA), and the gold standard of treatment, ACL reconstruction, does not reduce this risk. The mechanism of PTOA in the ACL injured joint is likely due both to the initial inflammation and ongoing subtle mechanical instability. Recently, intra-articular implantation of a collagen-platelet composite (CPC) during surgery in animal models has been shown to improve healing following bio-enhanced ACL repair or ACL reconstruction procedures, though the impact of the CPC on articular cartilage remains unknown.We hypothesize that cartilage integrity following bio-enhanced ACL repair (BE-repair) and bio-enhanced ACL reconstruction (BE-ACLR) is improved when compared to traditional ACL reconstruction (ACLR) or ACL transection with no treatment (ACLT). Methods: With IACUC approval, 31 adolescent minipigs underwent surgical ACL transection in one knee followed by BE-repair (n=8), BE-ACLR (n=8), ACLR (n=8), and no treatment (ACLT; n=7). After 12 months of healing, the articulating surfaces of the surgically treated and contralateral ACL intact knees were macroscopically graded following application of India ink using a five point scale (0=no changes; 1=intact surface with color changes; 2=surface fibrillation; 3=exposed bone10%). The surface areas of all lesions were determined using calipers and an elliptical fit. A mixed linear model was used to make comparisons between treatments (BE-repair, BE-ACLR, ACLR, and ACLT) and compartments (medial femoral condyle, lateral femoral condyle, medial tibial plateau, and lateral tibial plateau). Similar analyses were performed to compare the lesion areas within each compartment. All statistical analyses were done on the difference between the surgical and contralateral ACL-intact knee within each animal. Results:We found significant mean differences in cartilage scores between treatments (p=0.05) and compartments (p<0.01). The mean difference (plus or minus) confidence interval for BE-repair, BE-ACLR, ACLR and ACLT (pooled across compartments) were 0.24(plus or minus)0.193, 0.16(plus or minus)0.241, 0.48(plus or minus)0.181, and 0.66(plus or minus)0.392, respectively. Only the knees treated with BE-ACLR did not have increased chondral injury on the surgical side. For the lesion area measurements, the treatment effect was statistically significant in the medial femoral condyle (p=0.012). The mean difference (plus or minus) confidence interval between the surgical and contralateral ACL-intact knees for BE-repair, BE-ACLR, ACLR and ACLT were 5(plus or minus)17.8mm2, -19(plus or minus)23.1mm2, 40(plus or minus)31.9mm2, and 57(plus or minus)51.5mm2, respectively. Both the BE-repair and BE-ACLR procedures resulted in mean differences between the operative and non-operative side that were not significantly different from zero. It should also be noted that there were no lesions in either the surgical or contralateral ACL intact knee in the lateral femoral condyle or medial tibial plateau for any animal undergoing BE-repair. Conclusions: ACL transection and ACL reconstruction both resulted in increased chondral damage of the knee at one year after surgery as noted in humans. In contrast, treatment of the ACL transection with either bio-enhanced repair with CPC or ACL reconstruction augmented with CPC prevented this increased chondral damage. These data suggest that the intra-articular application of CPC may be chondroprotective.
Fleming, B. C., Machan, J. T., Shalvoy, M. R., & Murray, M. M. (2012). A collagen-platelet composite to stimulate healing after acl surgery also minimizes cartilage damage in the acl injured knee. Osteoarthritis and Cartilage, 20, S68–S69. https://doi.org/10.1016/j.joca.2012.02.045