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32 Spontaneous healing of the ruptured anterior cruciate ligament: observations from the KANON trial
  1. Stephanie Filbay1,
  2. Frank Roemer2,3,
  3. Stefan Lohmander4,
  4. Aleksandra Turkiewicz4,
  5. Ewa M Roos5,
  6. Richard Frobell4,
  7. Martin Englund2,4
  1. 1Centre for Health, Exercise and Sports Medicine; Department of Physiotherapy; University Of Melbourne, Australia
  2. 2School of Medicine, Boston University, USA
  3. 3Friedrich-Alexander University of Erlangen-Nürnberg, Germany
  4. 4Orthopedics, Department of Clinical Sciences, Lund University, Sweden
  5. 5Department of Sports and Clinical Biomechanics, University of Southern Denmark, Denmark


Introduction It is often assumed that an acutely ruptured ACL cannot heal. We evaluated ACL healing using MRI within 5 years of ACL rupture; described 2- and 5-year outcomes stratified by healing status and treatment; and investigated the relationship between ACL healing, sport/recreational function and quality of life (QOL) at 2- and 5-years following ACL injury.

Materials and Methods Secondary analysis of KANON Trial data following randomisation to rehabilitation and optional delayed ACL reconstruction (ACLR), or early-ACLR. Outcomes included Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales, activity level, mechanical stability, and osteoarthritis. Mixed linear regression estimated the relationship between healing status, KOOS-Sports/Rec and KOOS-QOL, adjusted for age, sex, smoking and unmeasured person-specific time-invariant confounding.

Results Following management with rehabilitation-alone at 5-years (n=26), 56% had a healed-ACL at 2-years and 58% at 5-years. One in twenty-three (4%) had a healed ACL before undergoing delayed-ACLR. People with a healed-ACL reported high KOOS scores at 2-years and 63–93% met the patient acceptable symptomatic state criteria, compared to 31–61% in the non-healed or reconstructed groups. Two-year KOOS Sport/Rec and QOL scores were worse in the non-healed (mean difference (95% CI) -21.9(-38.8, -5.0); -26.9(-41.7, -12.1)), delayed-ACLR (-25.0 (-39.8, -10.1); -19.4(-32.3, -6.4)) and early-ACLR (-18.0(-31.5, -4.5); -13.9(-25.6, -2.1)) groups compared to the healed-ACL group, or findings excluded the possibility of better findings in the reconstructed groups.

Conclusion There was a high rate of ACL healing in patients managed with rehabilitation alone and these individuals reported better patient-reported outcomes compared to the non-healed and reconstructed groups.

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