Tears of popliteomeniscal fascicles, diagnostic and clinical implications. A review of the evidence.

Postero-lateral corner of the knee is composed of several structures including the popliteo-meniscal fascicles (PMFs). These fibrous structures form a stable ligamentous complex around the popliteus tendon, which stabilize the lateral meniscus, increasing the strength of postero-lateral corner. Studies were retrieved through an electronic search of CINAHL, EMBASE, and Pub-Med, until May 2016. Studies in English, Italian, French, and Spanish were considered for inclusion. Randomized controlled trials, prospective and retrospective comparative studies, case series, and case reports were included. Studies eligible for inclusion concerned PMFs anatomy, biomechanics, diagnostic assessment of PMFs tears and clinical options for tears management. Thirteen studies were included in this review. There were: 7 case series, 4 case reports and 3 anatomical studies. Through anatomic dissection, two or three PMFs (antero-inferior fascicle, aiPMF; postero-superior fascicle, psPMF; postero-inferior fascicle, piPMF) can be indentified and isolated. Evaluation through MRI can be a useful diagnostic tool in detecting PMFs tears, especially using proton density (PD) sequences. The biomechanical analysis assessed that lateral meniscus (LM) motion is directly related with PMFs integrity and increased with section of one or both the fascicles. The clinical studies clearly state that a snapping syndrome, associated with lateral knee pain, can develop when one or both PMFs are torn. The three PMFs described are considered as relevant components of the popliteal hiatus, in the posterolateral aspect of the knee. MRI evaluation can detect these fibrous fascicles with good sensitivity. More studies with larger samples would be needed for a clear comprehension of PMFs function and clinical management of PMFs tears, especially with large case series and modern biomechanical testing.