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Meaningful thresholds for patient-reported outcomes following interventions for anterior cruciate ligament tear or traumatic meniscus injury: a systematic review for the OPTIKNEE consensus
  1. Erin M Macri1,2,3,
  2. James J Young4,5,
  3. Lina Holm Ingelsrud6,
  4. Karim M Khan3,7,
  5. Berend Terluin8,
  6. Carsten Bogh Juhl4,9,
  7. Jackie L Whittaker10,11,
  8. Adam G Culvenor12,
  9. Kay M Crossley12,
  10. Ewa M Roos4
  1. 1 Department of Orthopaedics and Sports Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
  2. 2 Dept General Practice, Erasmus University Medical Center, Rotterdam, The Netherlands
  3. 3 Department of Family Practice, University of British Columbia, Vancouver, British Columbia, Canada
  4. 4 Center for Muscle and Joint Health, University of Southern Denmark, Odense, Denmark
  5. 5 Research Division, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada
  6. 6 Copenhagen University Hospital Hvidovre, Kobenhavn, Denmark
  7. 7 School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
  8. 8 Department of General Practice, Amsterdam UMC, VU University, Amsterdam, The Netherlands
  9. 9 Department of Physiotherapy and Occupational Therapy, Copenhagen University Hospital, Herlev-Gentofte, Copenhagen, Denmark
  10. 10 Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
  11. 11 Arthritis Research Canada, Richmond, British Columbia, Canada
  12. 12 La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora, Victoria, Australia
  1. Correspondence to Professor Kay M Crossley, La Trobe University, Bundoora, VIC 3086, Australia; k.crossley{at}


Objective We synthesised and assessed credibility (ie, trustworthiness) of thresholds that define meaningful scores for patient-reported outcome measures (PROMs) following interventions for anterior cruciate ligament (ACL) tear or traumatic meniscus injury.

Design Systematic review, narrative synthesis.

Data sources We searched five databases, handsearched references of included studies and tracked citations.

Eligibility Included studies investigated: individuals with ACL tear or meniscus injury; mean age <35 years; and PROM thresholds calculated using any method to define a minimal important change (MIC) or a meaningful post-treatment score (Patient Acceptable Symptom State (PASS) or Treatment Failure).

Results We included 18 studies (15 ACL, 3 meniscus). Three different methods were used to calculate anchor-based MICs across 9 PROMs, PASS thresholds across 4 PROMs and treatment failure for 1 PROM. Credibility was rated ‘high’ for only one study—an MIC of 18 for the Knee injury and Osteoarthritis Outcome Score Quality-of-life (KOOS-QOL) subscale (using the MID Credibility Assessment Tool). Where multiple thresholds were calculated among ‘low’ credibility thresholds in ACL studies, MICs converged to within a 10-point range for KOOS-Symptoms (−1.2 to 5.4) and function in daily living (activities of daily living, ADL 0.5–8.1) subscales, and the International Knee Documentation Committee Subjective Knee Form (7.1–16.2). Other PROM thresholds differed up to 30 points. PASS thresholds converged to within a 10-point range in KOOS-ADL for ACL tears (92.3–100), and KOOS-Symptoms (73-78) and KOOS-QOL (53-57) in meniscus injuries.

Conclusion Meaningful PROM thresholds were highly susceptible to study heterogeneity. While PROM thresholds can aid interpretability in research and clinical practice, they should be cautiously interpreted.

  • anterior cruciate ligament
  • meniscus
  • systematic review

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  • Twitter @James_J_Young, @LIngelsrud, @KarimKhan_IMHA, @jwhittak_physio, @agculvenor, @ewa_roos

  • Contributors Priority themes for all OPTIKNEE activities were established by JLW, AGC, KMC, EMR and CBJ, all of whom are also founders and Steering Committee members of OPTIKNEE. The research question was developed by EMR and EM, and all coauthors gave input and final approval to the conception of the study. The study protocol was developed by EM, JJY and EMR, with critical input from all coauthors. Data acquisition and analysis was performed by EM and JJY, with additional input from LHI, EMR and remaining coauthors as needed. Interpretation of results was performed by EM, JJY, LHI, KMK, BT, CBJ, JLW, AGC, KMC, EMR. Manuscript was drafted by EM and JJY, and critical input for manuscript edits and revisions was provided by LHI, KMK, BT, CBJ, JLW, AGC, KMC, EMR. All coauthors gave final approval of the submitted version. EM and EMR accept full responsibility for the work and conduct of the study as a whole.

  • Funding This review is part of the OPTIKNEE consensus ( which has received funding from the Canadian Institutes of Health Research (OPTIKNEE principal investigator JLW #161821). Initial priority theme setting was supported by a La Trobe University Research Focus Area Collaboration Grant (OPTIKNEE principal investigator AGC).

  • Disclaimer The funders had no role in any part of the study or in any decision about publication.

  • Competing interests EMR is deputy editor of the scientific journal Osteoarthritis and Cartilage for which she receives an annual honorarium; she is the developer of Knee injury and Osteoarthritis Outcome Score (KOOS) and several other freely available patient-reported outcome measures (; is cofounder of the Good Life with Osteoarthritis in Danmark (GLA:D), a not-for profit initiative to implement clinical guidelines in primary care hosted by University of Southern Denmark. CBJ is an Associate Editor of Osteoarthritis and Cartilage. KMK holds a CIHR Scientific Director Grant which supports his academic time; receives royalties as an author of Brukner and Khan’s Clinical Sports Medicine (book); received consulting fees from Aspetar Orthopaedic and Sports Medicine Hospital during 2019–2020; received some speaker honoraria for presenting at a small number of conferences (such as the Alaska branch of the American Physical Therapy Association); received support for attending International Olympic Committee events: Advanced Team Physician Course(s) and the 6th World Conference on Sports Injury and Illness Prevention; and participated in one UBC trial patient safety board. JJY is supported by PhD funding support from the Danish Foundation for Chiropractic Research and Post-graduate Education, Ontario Chiropractic Association, Canadian Memorial Chiropractic College, the National Chiropractic Mutual Insurance Company Foundation, and the University of Southern Denmark. JLW is supported by the Michael Smith Foundation for Health Research and the Arthritis Society. JLW is a Senior Associate Editor of the Journal of Orthopaedic and Sports Physical Therapy. KMC is a senior advisor of BJSM. KLM is a project leader of the Good Life with Osteoarthritis from Denmark – Australia (GLA:D), a not-for profit initiative to implement clinical guidelines in primary care hosted by La Trobe University. KLM has received grant funding from NHMRC Project Grant: SUPER rehabilitation for young people with old knees GNT1158500 that is not related to the present study but funds a study with similar aims as those of the OPTIKNEE group (optimising outcomes after knee surgery). AGC is a recipient of a National Health and Medical Research Council (NHMRC) of Australia Investigator Grant (GNT2008523). JLW, AGC and EM are Associate Editors of the British Journal of Sports Medicine (BJSM). All other authors declare no competing interests.

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

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.