Discoid menisci can be symptomatic from instability or a tear. A torn discoid meniscus is likely to require repair to preserve meniscal function and should not be missed. This is the first study to evaluate a range of pre-operative methods to predict the likelihood of a torn discoid meniscus.
A retrospective analysis of prospectively collected data was performed. Clinical, radiographic and operative data were reviewed. Patients were grouped based on the presence of a tear or not during surgery. All patients underwent MRI scans pre-operatively which were validated with arthroscopy findings to calculate sensitivity. All patients completed Pedi-KOOS and Pedi-IKDC pre-operative scores.
There were 32 discoid menisci in 27 patients. Mean age at surgery was 10.4 years (6–16). Nineteen patients were female. Seventeen menisci were identified as torn at time of arthroscopy (53%), 15 were unstable but not torn. Clinical findings did not differentiate between the torn or unstable menisci. MRI was only 75% sensitive and 50% specific at identifying a torn discoid meniscus. There was no statistical difference between KOOS-child (n.s.) and Pedi-IKDC (n.s.) scores between the groups.
MRI is neither sensitive nor specific at identifying tears in discoid menisci. There is no difference in pre-operative outcome scores for patients with a torn or unstable discoid meniscus; pre-operative PROMs are a poor predictor of a meniscal tear. This study emphasises that pre-operative tests and clinical findings are not conclusive for identifying a meniscal tear and the operating surgeon should be vigilant in identifying and repairing tears at the time of surgery. Pre-operative findings poorly correlate to arthroscopic findings and potential surgical interventions required. Patients and parents/carers should, therefore, be appropriately counselled prior to surgery that post-operative measures are dependent on intra-operative findings and not pre-operative findings in patients.
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We received no sources of support for this study, no funding was required, and no industry was involved in setting up or performing this study. No funding was received from any parties for this study.
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Hampton, M., Hancock, G., Christou, A. et al. Clinical presentation, MRI and clinical outcome scores do not accurately predict an important meniscal tear in a symptomatic discoid meniscus. Knee Surg Sports Traumatol Arthrosc 29, 3133–3138 (2021). https://doi.org/10.1007/s00167-020-06375-w
- Discoid tear