The detached stump of the torn anterior cruciate ligament adheres to the femoral notch wall and then to the posterior cruciate ligament within 6 months from injury.

PURPOSE: To evaluate the progressive changes in the morphology of traumatic ruptures of the anterior cruciate ligament (ACL) over time. A secondary objective was evaluating their correlation with meniscal tears or chondral lesions.

METHODS: The study included one hundred and one patients who underwent ACL reconstruction surgery of the knee after a definite date of injury. The torn ACL remnant morphological pattern was assessed and classified during arthroscopy. A correlation analysis was performed between the pathological features of the remnant and the time length from injury. In addition, correlation between ACL remnant subtypes and meniscal tears or chondral lesions was evaluated.

RESULTS: At surgery there were four distinct ACL tear morphological patterns that were correlated to the time span from injury (r = 0.61, p < 0.001) and ended with scarring of the femoral remnant to the posterior cruciate ligament. The early pattern was noticed within median time of 2.6 months from injury and appeared as a separate stump with no scar tissue. The following two patterns appeared within 6 months from injury and were characterized by adhesion of scar tissue to different locations in the femoral notch. The last morphological pattern appeared as adherence of the ACL stump to the posterior cruciate ligament. This pattern was seen in some patients within 6 months from injury but was the dominant pattern later on and was also correlated with meniscal tears.

CONCLUSIONS: During the first 3 months from injury the gross morphological features of the torn ACL remnant showed no scar. This phase was followed by scarring of the femoral remnant at first to the femoral notch, and eventually to the posterior cruciate ligament within 6 months from injury and later on. Therefore, further research on the healing potential of the human ACL stump and its biological environment should be focused on the first 3 months from injury.

STUDY DESIGN: Case series; Level of evidence, 4.