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Delaying ACL reconstruction and treating with exercise therapy alone may alter prognostic factors for 5-year outcome: an exploratory analysis of the KANON trial
  1. Stephanie R Filbay1,
  2. Ewa M Roos2,
  3. Richard B Frobell3,
  4. Frank Roemer3,4,5,
  5. Jonas Ranstam6,
  6. L Stefan Lohmander3
  1. 1Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
  2. 2Research Unit for Musculoskeletal Function and Physiotherapy, Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
  3. 3Department of Clinical Sciences Lund, Orthopaedics, Lund University, Faculty of Medicine, Lund, Sweden
  4. 4Department of Radiology, University of Erlangen-Nuremberg, Erlangen, Germany
  5. 5Quantitative Imaging Center (QIC), Department of Radiology, Boston University School of Medicine, Boston, Massachusetts, USA
  6. 6Independent Statistician, Mdas AB, Ystad, Sweden
  1. Correspondence to Dr Stephanie R Filbay, Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Institute of Musculoskeletal Sciences, Windmill Road, Headington, Oxfordshire OX3 7LD, UK; stephanie.filbay{at}


Aim Identify injury-related, patient-reported and treatment-related prognostic factors for 5-year outcomes in acutely ACL-ruptured individuals managed with early reconstruction plus exercise therapy, exercise therapy plus delayed reconstruction or exercise therapy alone.

Methods Exploratory analysis of the Knee Anterior Cruciate Ligament, Nonsurgical versus Surgical Treatment (KANON) trial (ISRCTN84752559). Relationships between prognostic factors (baseline cartilage, meniscus and osteochondral damage, baseline extension deficit, baseline patient-reported outcomes, number of rehabilitation visits, graft/contralateral ACL rupture, non-ACL surgery and ACL treatment strategy) and 5-year Knee Injury and Osteoarthritis Outcome Score (KOOS) pain, symptoms, sport/recreation and quality of life (QOL) scores were explored using multivariable linear regression. Estimates were adjusted for sex, age, body mass index, preinjury activity level, education and smoking.

Results For all participants (n=118), graft/contralateral ACL rupture, non-ACL surgery and worse baseline 36-item Short-Form Mental Component Scores were associated with worse outcomes. Treatment with exercise therapy alone was a prognostic factor for less knee symptoms compared with early reconstruction plus exercise therapy (regression coefficient 10.1, 95% CI 2.3 to 17.9). Baseline meniscus lesion was associated with worse sport/recreation function (−14.4, 95% CI −27.6 to –1.3) and osteochondral lesions were associated with worse QOL (−12.3, 95% CI −24.3 to –0.4) following early reconstruction plus exercise therapy. In the same group, undergoing additional non-ACL surgery and worse baseline KOOS scores were prognostic for worse outcome on all KOOS subscales. Following delayed reconstruction, baseline meniscus damage was a prognostic factor for less pain (14.3, 95% CI 0.7 to 27.9). Following exercise therapy alone, undergoing non-ACL surgery was prognostic for worse pain.

Conclusions Treatment-dependent differences in prognostic factors for 5-year outcomes may support individualised treatment after acute ACL rupture in young active individuals.

Trial registration number Current Controlled Trials ISRCTN84752559.

  • exercise therapy or rehabilitation
  • arthroscopic surgery
  • meniscus
  • cartilage
  • pain
  • quality of life

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See:

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  • Contributors SRF, EMR and LSL conceived and designed this exploratory analysis. SRF, EMR, RBF, FR, JR and LSL participated in the analysis. SRF drafted the first version of the manuscript. All authors contributed in revising the manuscript and gave their final approval of the submitted version.

  • Funding The KANON study received funding from the Swedish Research Council (RBF, LSL, EMR), Medical Faculty of Lund University (RBF, LSL, EMR), Region Skåne (LSL, RBF, EMR), Thelma Zoegas Fund (RBF), Stig & Ragna Gorthon Research Foundation (RBF), Swedish National Centre for Research in Sports (LSL, RBF), Crafoord Foundation (RBF), Tore Nilsson Research Fund (RBF) and Pfizer Global Research (LSL). SRF was awarded an Osteoarthritis Research Society International young investigator scholarship to support this collaboration. The funders had no role in any part of the study or the decision to publish.

  • Competing interests EMR is deputy editor of Osteoarthritis and Cartilage, the developer of Knee injury and Osteoarthritis Outcome Score and founder of the Good Life with Osteoarthritis in Denmark initiative to implement clinical guidelines in primary care; FR is a shareholder of Boston Imaging Core Lab, outside the submitted work; JR reports personal fees from consultations, outside the submitted work. SRF, RBF and LSL have nothing to disclose.

  • Ethics approval Lund University Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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