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Loss of patellofemoral cartilage thickness over 5 years following ACL injury depends on the initial treatment strategy: results from the KANON trial
  1. Adam G Culvenor1,2,
  2. Felix Eckstein2,3,
  3. Wolfgang Wirth2,3,
  4. L Stefan Lohmander4,
  5. Richard Frobell4
  1. 1 La Trobe Sport and Exercise Medicine Research Centre, La Trobe University, Bundoora, Victoria, Australia
  2. 2 Institute of Anatomy, Paracelsus Medical University Salzburg and Nuremburg, Salzburg, Austria
  3. 3 Chondrometrics GmbH, Ainring, Germany
  4. 4 Faculty of Medicine, Department of Clinical Sciences Lund, Orthopaedics, Lunds Universitet, Lund, Sweden
  1. Correspondence to Dr Adam G Culvenor, La Trobe Sport and Exercise Medicine Research Centre, La Trobe University, Bundoora, Victoria, Australia; a.culvenor{at}


Objectives To evaluate changes in patellofemoral cartilage thickness over 5 years after anterior cruciate ligament (ACL) injury and to determine the impact of treatment strategy.

Methods 121 adults (ages 18–35 years, 26% women) had an ACL injury and participated in the KANON randomised controlled trial. Of those, 117 had available MRIs at baseline (<4 weeks post-ACL rupture) and at least one follow-up measurement (2, 5 years). Patellofemoral cartilage thickness was analysed by manual segmentation (blinded to acquisition order). Patellar, trochlear and total patellofemoral cartilage thickness changes were compared between as-randomised (rehabilitation+early ACL reconstruction (ACLR) (n=59) vs rehabilitation+optional delayed ACLR (n=58)) and as-treated groups (rehabilitation+early ACLR (n=59) vs rehabilitation +delayed ACLR (n=29) vs rehabilitation alone (n=29)).

Results Patellofemoral cartilage thickness decreased −58 µm (95% CI −104 to –11 µm) over 5 years post-ACL rupture, with the greatest loss observed in trochlea during the first 2 years. Participants randomised to rehabilitation+early ACLR had significantly greater loss of patellar cartilage thickness compared with participants randomised to rehabilitation+optional delayed ACLR over the first 2 years (−25 µm (−52, 1 µm) vs +14 µm (−6 to 34 µm), p=0.02) as well as over 5 years (−36 µm (−78 to 5 µm) vs +18 µm (−7, 42 µm), p=0.02). There were no statistically significant differences in patellofemoral cartilage thickness changes between as-treated groups.

Conclusion Patellofemoral (particularly trochlear) cartilage thickness loss was observed in young adults following acute ACL rupture. Early ACLR was associated with greater patellofemoral (particularly patellar) cartilage thickness loss over 5 years compared with optional delayed ACLR, indicating that early surgical intervention may be associated with greater short-term structural patellofemoral cartilage deterioration compared with optional delayed surgery.

Trial registration number ISRCTN84752559; Post-results.

  • patella
  • trochlea
  • knee
  • anterior cruciate ligament
  • cartilage

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  • Contributors All authors contributed to the conception and design of the study. LSL, RF, FE and WW contributed to the acquisition of the data. All authors contributed to the analysis and interpretation of the study, revised the manuscript critically for important intellectual content and approved the final version of the manuscript.

  • Funding The KANON study received funding from the Swedish Research Council (RBF, LSL), Medical Faculty of Lund University (RBF, LSL), Region Skåne (LSL, RBF), Thelma Zoegas Fund (RBF), Stig & Ragna Gorthon Research Foundation (RBF), Swedish National Centre for Research. AGC is a recipient of a National Health and Medical Research Council (NHMRC) of Australia Early Career Fellowship (Neil Hamilton Fairley Clinical Fellowship, APP1121173).

  • Disclaimer The sponsors were not involved in the design and conduct of this particular study, in the analysis and interpretation of the data and in the preparation, review or approval of the manuscript.

  • Competing interests FE is CEO of Chondrometrics GmbH, a company providing MR image analysis services to academic researchers and to industry. He has provided consulting services to EMD Serono, Bioclinica/Synarc, Samumed, Servier, Kolon-Tissuegene, Roche and Galapagos, has prepared educational sessions for Medtronic and has received research support from Pfizer, Eli Lilly, Merck Serono, Novartis, Stryker, Abbvie, Kolon, Synarc, Ampio, BICL, Orthotrophix, Kolon-Tissue Gene, Servier and Galapagos. WW has a part time employment with Chondrometrics GmbH and is a co-owner of Chondrometrics GmbH.

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

  • Patient consent for publication Not required.