Quantitative and Qualitative Assessment of Posterolateral Meniscal Anatomy: Defining the Popliteal Hiatus, Popliteomeniscal Fascicles, and the Lateral Meniscotibial Ligament

Background: Surgical treatment of lateral meniscal tears can be challenging due to the greater mobility of the lateral meniscus, thin capsule, and management of the popliteal hiatus. There has been a lack of quantitative assessments of the structural attachments to the posterior horn of the lateral meniscus (PHLM) to guide repairs. Purpose: To qualitatively and quantitatively describe the anatomy of the PHLM, popliteomeniscal fascicles, and the posterolateral capsule. Study Design: Descriptive laboratory study. Methods: Fourteen male, nonpaired, fresh-frozen cadaveric knees were used. The attachments of the posterolateral capsule, popliteomeniscal fascicles, and meniscofemoral ligaments to the lateral meniscus and the attachment of the meniscotibial ligament to the tibia were identified. A 3-dimensional coordinate measuring system was used to measure the relationships of these attachments to surgically relevant landmarks and their structural relationship with the lateral meniscus. Results: The posterolateral capsule attachment had a confluent attachment at the superior margin of the PHLM, quantitatively attaching to the proximal 11% of the total height of the PHLM. On average, the length of the posterolateral capsule attachment to the superior surface of the PHLM was 16.7 ± 2.7 mm. The average length of the meniscotibial attachment to the posteroinferior aspect of the meniscus was 12.8 ± 3.9 mm. There was a lack of ligamentous attachments to the lateral meniscus between the lateral aspect of the meniscotibial ligament and the anterior aspect of the anterosuperior popliteomeniscal fascicle, where only popliteomeniscal fascicle and capsular attachments to the posterior meniscus were present. Conclusion: This anatomic study provides quantitative guidelines for the complex attachments to the PHLM. Knowledge of the quantitative descriptions of these attachments may aid in an improved intraoperative diagnosis of PHLM tears that extend to the popliteal hiatus, and further studies related to the surgical repair of the intricate attachments to the PHLM are recommended. Clinical Relevance: The findings of this study provide the anatomic foundation for an improved understanding of the role of the meniscocapsular, meniscotibial, and popliteomeniscal fascicle attachments of the posterolateral meniscus. Understanding the differences between the lengths of the superior and inferior aspects of the popliteal hiatus will help to further refine characterization of tears extending into the popliteal hiatus and to avoid potential overconstraint of the more mobile lateral meniscus during a repair by anatomically reproducing its native structural attachments.