Adults Have a Higher Incidence of Discoid Lateral Meniscus Tears Than Children-Adults Tend to Present With Complex Tears, While Horizontal Tear Patterns Are Frequently Encountered in Children: A Systematic Review.

Purpose: To systematically review the available literature on patients with discoid lateral meniscus (DLM) with the goal of elucidating the rates and types of meniscal tears, clinical symptoms, treatment strategies, and postoperative clinical and radiographic outcomes in adult patients compared with a pediatric population.

Methods: A literature search was performed using the PubMed, Embase, and Scopus databases from database inception to October 2023 according to the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Level of evidence I through IV human clinical studies evaluating rate and type of meniscal tears, clinical symptoms, patient-reported outcome measures, and postoperative radiographical assessments in patients with DLM were included. Comparisons were made by age younger and older than 16 years. Study quality was assessed using the Methodological Index for Non-Randomized Studies criteria.

Results: Thirteen studies comprising 1,772 adult patients (>16 years old) with DLM (n = 1,856 knees) and 8 studies conducted in 304 pediatric patients (≤16 years old, n = 353 knees) were included. The reported mean age ranged from 22.4 to 45 years (mean follow-up, 24-157.5 months) in the adult group and from 5 to 12.9 years (mean follow-up, 37-234 months) in the pediatric DLM group. Among studies that reported on tear patterns, the majority of adult (n = 553; 96.5%) and pediatric (n = 163; 71.8%) patients had tears of the DLM. Complete DLM was the predominant type of DLM in both study groups (range in adults, 49.6% to 88%; range in pediatric patients, 19%-100%) with complex (46.1%; range, 5.3%-100%) and horizontal tears (18.2%; range, 20%-37.5%) being the most frequently described tear patterns in the adult and pediatric DLM groups, respectively. Pain was the predominant reported symptom in both study groups (range in adults, 12.1%-99.3%; range in pediatric patients, 32.4%-100%). Partial meniscectomy was the most frequently reported treatment option conducted in 334 adult knees (39.5%; range, 24.2%-100%) and 66 pediatric knees (63.5%; range, 15%-100%). Overall, improved postoperative clinical outcomes were reported in both study groups; however, radiographic progression of degenerative changes after subtotal meniscectomy was noted.

Conclusions: More adult patients with DLM present with tears in the literature compared with the pediatric population. Complex and horizontal tear patterns are the most frequently reported tears in adult and pediatric patients, respectively. Pain was the most relevant symptom in both study groups. There was generally significant improvement in postoperative clinical outcome scores; partial meniscectomy, however, remains the most frequently reported treatment option and is associated with fewer degenerative changes than in subtotal meniscectomy.

Level Of Evidence: Level IV, systematic review of Level I to IV studies.