Recovery of ACL function after dynamic intraligamentary stabilization is resultant to restoration of ACL integrity and scar tissue formation

Purpose Dynamic intraligamentary stabilization (DIS) is recognized as a ligament preserving technique for the treatment of acute anterior cruciate ligament (ACL) injuries. The aim of this study was to assess the integrity and morphology of the recovered ACL after DIS repair. Methods The cohort comprised 47 patients with an acute proximal ACL rupture undergoing DIS repair. All patients underwent diagnostic arthroscopy after a minimum postoperative interval of 6 months for semi-quantitative evaluation of ACL integrity, function and scar tissue formation. Tegner, Lysholm and International Knee Documentation Committee (IKDC) scores as well as objective anteroposterior (ap) translation were assessed at 6 weeks, 3-, 6- and 12 months postoperatively. Results Full restoration of the ACL volume was affirmed in 30 (63.8%) patients and two-third restoration in 13 (27.7%). Hypertrophic scar formation was observed in 23 (48.9%) patients. Forty-four patients (93.6%) demonstrated sufficient ACL tensioning intraoperatively upon anterior stress. At final follow-up, the median Tegner activity level was 5.5 (3–10), Lysholm and IKDC scores were 100 (64–100) and 94 (55–100) points, respectively. The mean ap-translation differed from the normal knee by 2.1 ± 2.2 mm. Deficient ACL recovery was noted in four patients (8.5%), none of which required secondary reconstructive surgery. Conclusion The results demonstrate that clinical recovery of ACL function after DIS repair is resultant to both restoration of ACL volume and scar tissue formation. Factors influencing the degree of scar tissue formation need further investigation to enable future attempts of guiding a balanced biological healing response. Level of evidence IV.