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Treatment for acute anterior cruciate ligament tear: five year outcome of randomised trial
  1. Richard B Frobell1,
  2. Harald P Roos1,
  3. Ewa M Roos2,
  4. Frank W Roemer3,4,
  5. Jonas Ranstam1,
  6. L Stefan Lohmander1,2,5
  1. 1Department of Orthopaedics, Clinical Sciences Lund, Lund University, Sweden
  2. 2Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
  3. 3Department of Radiology, University of Erlangen, Erlangen, Germany
  4. 4Quantitative Imaging Center (QIC), Department of Radiology, Boston University School of Medicine, Boston, MA, USA
  5. 5Department of Orthopaedics and Traumatology, University of Southern Denmark, Odense, Denmark
  6. EDITORIAL by Levy and colleagues
  7. Listen to a podcast about management of cruciate ligament tear five years on with Richard Frobell, an associate professor in the Department of Orthopaedics at Lund University, Sweden
  1. Correspondence to: R B Frobell, Department of Orthopaedics, Lund University Hospital, SE-22185 Lund, Sweden; Richard.frobell{at}


STUDY QUESTION In young active adults with an acute anterior cruciate ligament (ACL) rupture, do patient reported or radiographic outcomes after five years differ between those treated with rehabilitation plus early ACL reconstruction and those treated with rehabilitation and optional delayed ACL reconstruction?

SUMMARY ANSWER At five years, patients assigned to rehabilitation plus early ACL reconstruction did not differ significantly in patient reported or radiographic outcomes from those assigned to initial rehabilitation with the option of having a later reconstruction if needed.

WHAT IS KNOWN AND WHAT THIS PAPER ADDS The relative efficacy of surgical reconstruction and rehabilitation for short and long term outcomes of ACL rupture is debated. Clinicians and young active adult patients should consider rehabilitation as a primary treatment option following an acute ACL tear.

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This was an extended follow-up of a prospective randomised trial comparing two treatment strategies: early ACL reconstruction and delayed optional reconstruction. All patients received similar structured rehabilitation.

Participants and setting

We enrolled 121 young active adults (mean age 26 years) with an acute ACL injury to a previously uninjured knee at the departments of orthopaedics at Skåne University Hospital and Helsingborg Hospital, Sweden. One patient was lost to five year follow-up.

Primary outcome(s)

The primary outcome was mean change from baseline to five years in the average score for four of the five subscales of the knee injury and osteoarthritis outcome score (KOOS4; 0-100, worst to best).

Main results and the role of chance

Thirty (51%) patients assigned to optional delayed ACL reconstruction had a delayed reconstruction (seven between two and five years). The mean improvement in KOOS4 score from baseline to five years was 42.9 points for those assigned to rehabilitation plus early ACL reconstruction and 44.9 for those assigned to rehabilitation plus optional delayed reconstruction (between group difference 2.0 points, 95% confidence interval −8.5 to 4.5; P=0.54 after adjustment for the baseline score). We found no statistically significant between group differences in KOOS4, any of the KOOS subscales, SF-36, Tegner activity scale, or incident radiographic osteoarthritis of the index knee in the full analysis set or in the as treated analysis.


We found no evidence of one treatment being more harmful than the other over two or five years.

Bias, confounding, and other reasons for caution

Patients and surgeons were blinded to allocation but not to treatment. Primary and secondary outcomes were patient reported. Radiographs were read blinded to allocation.

Generalisability to other populations

Our results apply to young active adults but not to professional athletes or to less than moderately active adults.

Study funding/potential competing interests

The KANON study received funding from the Swedish Research Council, Medical Faculty of Lund University, Region Skåne, Thelma Zoegas Fund, Stig & Ragna Gorthon Research Foundation, Swedish National Centre for Research in Sports, Crafoord Foundation, Tore Nilsson Research Fund, and Pfizer Global Research. LSL has received honorariums for lectures from Pfizer.

Trial registration number

Current Controlled Trials ISRCTN84752559.


  • This is a summary of a paper that was published on as BMJ 2013;346:f232

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