Spontaneous healing in complete ACL ruptures: a clinical and MRI study

Most authors believe the ACL does not spontaneously heal after a complete rupture. Although several studies have reported spontaneous healing of torn ACLs, it is difficult to determine its healing potential and whether patients will be able to return to sports activities.

We therefore asked whether (1) a complete ACL rupture in patients can spontaneously heal without the use of a specific rehabilitation program or bracing and (2) patients are able to return to their athletic activity after spontaneous ACL healing.

We retrospectively reviewed 14 patients with acute ACL injury established by physical examination and MRI (proximal third in eight patients and the midligament in six). Average age at injury was 31 years (range, 23-41 years). All patients were athletically active before injury. Surgery was indicated in all patients but for various reasons postponed. We obtained International Knee Documentation Committee scores, Lysholm-Gillquist scores, and MRI. The minimum followup was 25 months (mean, 30 months; range, 25-36 months).

At last followup, the mean Lysholm-Gillquist score was 97. According to the International Knee Documentation Committee evaluation, 10 knees were normal and four nearly normal. All knees regained end point with a negative pivot shift test; MRI at followup showed an end-to-end continuous ACL with homogeneous signal. All patients returned to their former activity level. However, after the study period, two patients had a rerupture of the ACL (2.5 years after the first lesion).

Our observations indicate an acutely injured ACL may eventually spontaneously heal without using an extension brace, allowing return to athletic activity.

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.