Development of the Popliteomeniscal Fasciculi in the Fetal Human Knee Joint

Purpose: The purpose of this study is to better understand the function of the popliteomeniscal fasciculi and their relationship to the popliteus tendon and the lateral meniscus by describing these structures during embryonic development.

Type Of Study: Anatomic dissection and histologic evaluation.

Methods: Twelve fresh-frozen lower extremity specimens (6 paired limbs) from second and third trimester human fetuses were obtained from spontaneous abortions. Each specimen was fixed in formalin and decalcified in 9.0% nitric oxide. The specimens were prepared by removal of all skin and most of the soft tissues before dissection of the lateral meniscus, parts of the posterolateral joint capsule, and the popliteus tendon and muscle. The right-side specimens were sectioned in the transverse plane, and the left-side specimens in the coronal plane. Histologic sections were prepared with H&E and Masson's trichrome stains. Light microscopy was used to evaluate the lateral meniscal attachment, with detailed attention to the popliteomeniscal fasciculi.

Results: The close interrelationship of lateral meniscus and popliteus tendon, especially during embryologic development, does give a better understanding how the fasciculi stabilize the lateral meniscus and allow the popliteus tendon to function as a retractor of the lateral meniscus. The fasciculi consist of 3 layers including a dense collagen layer, a vascular layer, and a synovial or capsular layer.

Conclusions: During embryologic development, the fasciculi appeared to provide a vascular supply to the lateral meniscus adjacent to the popliteal hiatus where the meniscus is devoid of capsular attachments.