Anatomic and Histologic Analyses of the Popliteal Hiatus Area of the Lateral Meniscus Reveal the Meniscofibular Ligament and the Posteroinferior Popliteomeniscal Fascicle Are Ligamentous Tissue.

PURPOSE: To characterize the anatomical structure and histological composition of connective tissue around the popliteal hiatus of the lateral meniscus (LM): the posterosuperior popliteomeniscal fascicle (PS-PMF), posteroinferior popliteomeniscal fascicle (PI-PMF), and anterior popliteomeniscal fascicle (A-PMF), meniscofibular ligament (MFL), and popliteofibular ligament (PFL). METHODS: Six fresh-frozen cadaveric knees from unpaired donors with intact anatomy, no history of surgical intervention, and no gross pathological alterations were labeled and dissected, including 3 male and female donors, with a mean age of 53 years (range: 39-68 years). The PS-PMF, PI-PMF, A-PMF, MFL, and PFL were examined anatomically, and histological analysis was performed. RESULTS: The PS-PMF originated from the posterior aspect of the popliteus tendon (PT), crossing its posterior border (n = 5/6) or originating from the superior aspect (n = 1/6), and inserted onto the LM superiorly. The PI-PMF originated from the anterior border of the PT (n = 5/6) or its superior aspect (n = 1/6) and inserted onto the LM inferiorly. Adipose tissue consistently separated the PS-PMF and the PI-PMF. An interfascicular interval between the MFL and PI-PMF was observed (n = 5/6). The MFL originated from the LM, connected superiorly to the A-PMF, and converged inferiorly with the PFL. Histologically, the MFL and PI-PMF exhibited ligamentous characteristic, and the A-PMF and the PS-PMF had a vascular synovial structure. CONCLUSIONS: The PS-PMF, PI-PMF, A-PMF, MFL, and PFL are distinct anatomical components. The PS-PMF and the PI-PMF form a combined encapsulation around the PT. The MFL and PI-PMF are ligamentous. Given the limited intrinsic healing capacity of MFL injuries, surgical repair combined with trephination of the PT or microfracture is recommended. CLINICAL RELEVANCE: This study enhances understanding of lesions in the connective tissue around the popliteal hiatus area, supporting more anatomically precise and biologically informed interventions.