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Non-operative treatment of ACL rupture with mild instability

  • Arthroscopy and Sports Medicine
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Archives of Orthopaedic and Trauma Surgery Aims and scope Submit manuscript



This study examined whether or not conservative treatment of an acutely injured anterior cruciate ligament (ACL) could be successful in a select group of patients. Routine ACL reconstruction surgery in all acute ACL-injured patients should be avoided. We hypothesize that acutely injured ACL with mild instability at the initial physical examination could be improved even if there is disruption of ACL fibers on magnetic resonance images (MRI).

Materials and methods

Among 232 acute ACL-injured patients who visited our institution from March 1997 to April 2006, 48 were treated non-operatively. Patients diagnosed with an acute ACL injury by MRI with Lachman test ≤grade 1 were treated non-operatively. In this study, 30 male and 18 female patients with a mean age of 31.8 years were enrolled. The initial and follow-up Lachman test and pivot shift test were performed 3 weeks after the injury. The Lysholm knee scoring scale, International Knee Documentation Committee (IKDC) score and KT-2000 were obtained at the last follow-up.


There were 12 complete (25%) and 36 incomplete ACL ruptures (75%). The patients were followed up clinically and with MRI for 21.5 and 11.3 months, respectively. The follow-up Lachman test improved to grade 0 in 41 patients (87%). Thirty-six patients (76%) showed no laxity in the follow-up pivot shift test. The last follow-up IKDC score was a mean value of 91.1 points. KT 2000 was performed in 40 patients with a mean side-to-side difference of 2.85 mm. Of 48 patients, 46 showed restored ACL continuity and 39 (84%) showed restored low signal intensity on MRI.


A selective group of ACL tears with mild instability (Lachman ≤grade 1), though these seem to be complete tears on MRI, can show restoration of their continuity and signals on the MRI. Joint laxity on physical examination was improved at follow-up. These results suggest that a select group of patients with an acute ACL injury can successfully undergo non-operative treatment. In addition, unnecessary early ACL reconstruction surgery should be avoided.

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Correspondence to Sang Soo Eun.

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Ahn, J.H., Chang, M.J., Lee, Y.S. et al. Non-operative treatment of ACL rupture with mild instability. Arch Orthop Trauma Surg 130, 1001–1006 (2010).

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