Clinical presentation, MRI and clinical outcome scores do not accurately predict an important meniscal tear in a symptomatic discoid meniscus

Abstract

PurposeDiscoid 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. MethodsA 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. ResultsThere 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. ConclusionMRI 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. Level of evidence III.

Medial Discoid Meniscus in Children: A Multicenter Case Series of Clinical Features and Operative Results

“…17 Our rate of bilateral discoid medial menisci was substantially lower at 1 of 21 patients. We did have 1 patient with discoid medial and lateral menisci, as did Jeannopoulos, 24 and 1 of 13 patients also had a discoid lateral meniscus as well as a discoid 20 34/39 3/39 6/39 Sabbag (2018) 35 60 12/60 Kang (2019) 25 47/60 23/60 15/60 36/60 Hampton (2021) 21 27/32 2/32 19/32 Hesse (2021) 23 71/78 30/71 Lins (2021) 27 25/30 {{ medial meniscus in the same knee in the study by Chen et al 10 Specifically, Chen et al 10 reported on 13 operatively treated patients with discoid medial menisci over a 43-year period at 1 hospital. Most of the 13 patients had knee pain and mechanical symptoms and signs.…”

Chinese Experts Consensus and Practice Guideline on Discoid Lateral Meniscus

“…The sensitivity and specificity of this criterion are 95% and 97%, respectively 100,101 . In addition, MRI has a certain diagnostic value in classification, tear type and location, and peripheral rim stability of DLM 48,95,102–107 . The diagnostic specificity and sensitivity of MRI in adult DLM tears are 100% and 97.8%, 108 but in children's DLM and its lesions are still controversial 47,109,110 …”

“…100,101 In addition, MRI has a certain diagnostic value in classification, tear type and location, and peripheral rim stability of DLM. 48,95,[102][103][104][105][106][107] The diagnostic specificity and sensitivity of MRI in adult DLM tears are 100% and 97.8%, 108 but in children's DLM and its lesions are still controversial. 47,109,110 In patients with unilateral symptomatic DLM, the probability of DLM in the contralateral knee is about 73%-97%, 6 and of the same type in both is 88%.…”

Feasibility and efficacy of ultrasound in the diagnosis of discoid lateral meniscus and its classification in children: protocol for a prospective, multicentre, diagnostic test study

“…Furthermore, more than 12% of children still experience motion artefacts after sedation, which may cause severe complications such as cardiopulmonary depression and brain development 19. Moreover, significant differences exist in the morphology and vascular distribution of DLM between children and adults, which may influence the diagnostic value of MRI for DLM in children 20 21. Therefore, the feasibility and efficacy of MRI for DLM diagnosis in children remain controversial, and exploring a new technique to solve this dilemma is necessary.…”