Summary
DM with anterior instability was prevalent in 50% of our cohort. Patients with anterior instability tend to be female, younger, and skeletally immature. MRI presents lower sensitivity to detect anterior instability compared with other types of presentation. Anterior instability repair leads to improved PROs, few complications, and few re-operations similar to other types of presentation.
Abstract
Objectives: Discoid meniscus (DM) is often associated with peripheral rim instability (PRI). While posterior instability has received considerable attention in the medical literature, there is relatively limited awareness regarding anterior instability in DM cases. DM classifications have historically only focused on meniscal width and posterior peripheral stability, but pediatric sports medicine surgeons have lower intra- and inter-observer reliability for diagnosing anterior compared to posterior DM tears. This study aims to shed light on the incidence, presentation, diagnosis, treatment, and patient reported outcomes (PROs) of anterior instability treatment in symptomatic DM patients.
Methods
A retrospective review was performed in a single institution to analyze patients who underwent arthroscopic treatment for symptomatic DM in 2014-2020 with minimum 2-year follow-up. The cohort was divided based on the presence of anterior instability. Group 1 consisted of patients with anterior PRI (isolated or combined with posterior PRI), and Group 2 represented non-anterior PRI (isolated posterior no PRI). All patients with anterior instability underwent repair by an outside-in technique. (Figure 1) Data collection included demographics, clinical presentation, meniscal pathology, surgical technique, re-operation rates, and complication rates. PROs were collected including Tegner-Lysholm, IKDC, and KOOS for symptom, pain, ADL, sport, and QOL. T-tests or Wilcoxon rank-sum tests were used for continuous variables and chi-square or Fisher's exact tests for categorical variables. Standard statistical analysis was applied with
Significance
level of p < 0.05.
Results
Fifty-nine patients were included. Overall, 30 (50.8%) of the cohort presented with anterior instability; of these, 40% were isolated and 60% were combined with posterior instability. Anterior instability patients tended to be female (60% vs 31%, p=0.02), younger (10.7 vs 12.8, p<0.01), and skeletally immature (70% vs 41%, p=0.02). Notably, the majority (83.3%) of patients with anterior or anterior/posterior combined instability exhibited vertical tears. MRI correlates with arthroscopic findings in 73.1% of anterior instability cases compare with 88.4% in other types of presentation (p=0.08). Compared with other types of presentation, anterior instability patients reported similarly good PROs and low numbers of re-operations and complications (2/30, 6.6% vs 2/29, 6.9%, p=0.99. PROs significantly improved from pre-operatively to post-operatively including Tegner-Lysholm (61.5 vs 93.5, p=0.04), Pedi-IKDC (54.4 vs 90.3, p=0.01), KOOS Symptom (64.4 vs 89.2, p=0.005), KOOS Pain (63.6 vs 93.0, p=0.005), KOOS ADL (80.0 vs 97.7, p=0.03), KOOS Sport (50.0 vs 92.8, p=0.01), and KOOS QOL (60.2 vs 79.1, p=0.02).
Conclusion
DM with anterior instability was prevalent in 50% of our cohort. Patients with anterior instability tend to be female, younger, and skeletally immature. MRI presents lower sensitivity to detect anterior instability compared with other types of presentation. Anterior instability repair leads to improved PROs, few complications, and few re-operations similar to other types of presentation. Our findings underscore the importance of further research focusing on anterior instability in DM cases. Additionally, they emphasize the necessity for surgeons to be aware of the potentially high incidence of anterior instability in patients with DM to lead to improved patient care and outcomes.