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 tend on 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) f rom second and third trimester human fetuses were obtained from spontaneous abortions. Each specimen was fixed in formalin and decalcified in 9.0% nit ric oxide. The specimens were prepared by removal of all skin and most of t he soft tissues before dissection of the lateral meniscus, parts of the pos terolateral joint capsule, and the popliteus tendon and muscle. The right-s ide specimens were sectioned in the transverse plane, and the left-side spe cimens in the coronal plane. Histologic sections were prepared with H&E and Masson's trichrome stains. Light microscopy was used to evaluate the later al meniscal attachment, with detailed attention to the popliteomeniscal fas ciculi. Results: The close interrelationship of lateral meniscus and poplit eus tendon, especially during embryologic development, does give a better u nderstanding how the fasciculi stabilize the lateral meniscus and allow the popliteus tendon to function as a retractor of the lateral meniscus. The f asciculi consist of 3 layers including a dense collagen layer, a vascular l ayer, and a synovial or capsular layer. Conclusions: During embryologic dev elopment, the fasciculi appeared to provide a vascular supply to the latera l meniscus adjacent to the popliteal hiatus where the meniscus is devoid of capsular attachments.