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Wild goose chase – no predictable patient subgroups benefit from meniscal surgery: patient-reported outcomes of 641 patients 1 year after surgery
  1. Kenneth Pihl1,
  2. Joie Ensor2,
  3. George Peat2,
  4. Martin Englund3,4,
  5. Stefan Lohmander5,
  6. Uffe Jørgensen6,
  7. Nis Nissen7,
  8. Jakob Vium Fristed8,
  9. Jonas Bloch Thorlund1
  1. 1 Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
  2. 2 Centre for Prognosis Research, Research Institute for Primary Care & Health Sciences, Keele University, Keele, UK
  3. 3 Department of Clinical Sciences Lund, Orthopedics, Clinical Epidemiology Unit, Lund University, Lund, Sweden
  4. 4 Clinical Epidemiology Research and Training Unit, Boston University School of Medicine, Boston, Massachusetts, USA
  5. 5 Department of Clinical Sciences Lund, Orthopedics, Lund University, Lund, Sweden
  6. 6 Department of Orthopedics and Traumatology, Odense University Hospital, Odense, Denmark
  7. 7 Department of Orthopedics, Lillebaelt Hospital, Kolding, Denmark
  8. 8 Department of Orthopedics, Lillebaelt Hospital, Vejle, Denmark
  1. Correspondence to Kenneth Pihl, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense 5230, Denmark; kpihl{at}


Background Despite absence of evidence of a clinical benefit of arthroscopic partial meniscectomy (APM), many surgeons claim that subgroups of patients benefit from APM.

Objective We developed a prognostic model predicting change in patient-reported outcome 1 year following arthroscopic meniscal surgery to identify such subgroups.

Methods We included 641 patients (age 48.7 years (SD 13), 56% men) undergoing arthroscopic meniscal surgery from the Knee Arthroscopy Cohort Southern Denmark. 18 preoperative factors identified from literature and/or orthopaedic surgeons (patient demographics, medical history, symptom onset and duration, knee-related symptoms, etc) were combined in a multivariable linear regression model. The outcome was change in Knee injury and Osteoarthritis Outcome Score (KOOS4) (average score of 4 of 5 KOOS subscales excluding the activities of daily living subscale) from presurgery to 52 weeks after surgery. A positive KOOS4 change score constitutes improvement. Prognostic performance was assessed using R2 statistics and calibration plots and was internally validated by adjusting for optimism using 1000 bootstrap samples.

Results Patients improved on average 18.6 (SD 19.7, range −38.0 to 87.8) in KOOS4. The strongest prognostic factors for improvement were (1) no previous meniscal surgery on index knee and (2) more severe preoperative knee-related symptoms. The model’s overall predictive performance was low (apparent R2=0.162, optimism adjusted R2=0.080) and it showed poor calibration (calibration-in-the-large=0.205, calibration slope=0.772).

Conclusion Despite combining a large number of preoperative factors presumed clinically relevant, change in patient-reported outcome 1 year following meniscal surgery was not predictable. This essentially quashes the existence of ‘subgroups’ with certain characteristics having a particularly favourable outcome after meniscal surgery.

Trial registration number NCT01871272.

  • arthroscopy
  • meniscus
  • prognosis
  • patient-reported outcomes
  • knee

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  • Correction notice This article has been corrected since it published Online First. The title has been corrected.

  • Contributors Concept and design: KP, JBT, JE, GP, ME and SL. Acquisition, analysis or interpretation of data: all authors. Drafting of the manuscript: KP and JBT. Critical revision of the manuscript for important intellectual content: all authors. Approval of final submitted version of manuscript: all authors.

  • Funding This study was supported by two individual grants (JBT) from the Danish Council for Independent Research | Medical Sciences (#12-125457 & #6110-00092B) and an individual PhD scholarship (KP) from the Region of Southern Denmark (#15/50982). The funders were not involved in any parts of the study or in any decision about publication.

  • Competing interests All authors have completed the ICMJE Form for Disclosure of Potential Conflicts of Interest. JBT and KP declare support from the Danish Council for Independent Research | Medical Sciences and the Region of Southern Denmark for the submitted work. No other disclosures were reported.

  • Patient consent for publication Not required.

  • Ethics approval The regional scientific ethics committee of Southern Denmark waived the need for ethical approval after reviewing the outline of KACS.19 Written informed consent to participate was obtained from all patients.

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

  • Data sharing statement No data are available.