Morphological Condition of the Remnant Tissue of 205 Patients According to the Time After Anterior Cruciate Ligament Injury.

Background: The adequate preservation of the anterior cruciate ligament (ACL) remnant at the time of ACLR (ACLR) may improve postoperative clinical outcomes.

Purpose: To determine the optimal time to perform remnant-preserving ACLR relative to ACL injury and, to this end, to evaluate the condition of the ACL remnant retrospectively at different time points after injury.

Study design: Cross-sectional study. Level of evidence 3.

Methods: Our study cohort comprised 205 patients who underwent ACLR. The patients were divided into 6 groups according to the time between injury and assessment in 2-week intervals up to 12 weeks. Based on their location and volume of the ACL remnant on arthroscopic images, the remnants were classified as follows using the modified Crain criteria: type 1, scarring to the posterior cruciate ligament; type 2, remnant attached to the notch; type 3, remnant attached to the femoral wall; type 4, resorption of the remnant; and type 5, remnant frayed like a mop end.

Results: The time after injury significantly correlated with the remnant tissue condition (P < .0001). Residual analysis revealed that Type 5 remnants were most common (P < .0001) and type 3 remnants were the least common (P < .0001) at 0 to 2 weeks after injury. Type 3A, 3B and 3C remnants were most common at 2 to 4 weeks after injury (P < .0001, P < .0001, and P = .0002, respectively).

Conclusion: Adequate remnant tissue (type 3) remained in the subacute phase (2 to 4 weeks) after ACL injury, whereas complete rupture of the remnant (type 4) was observed in the acute phase (0 to 2 weeks).