Femoral Entrapment

A normal hip shows a concentric reduction of the femoral head in the acetabulum - the joint space is equidistant all around the hip. The tear-drop represents the medial wall of the acetabulum. The distance from the tear-drop to the femoral head maybe compared with the contralateral side. On a perfectly positioned film, an increase in this distance is abnormal and may represent a hip effusion, infolded labrum after dislocation or intra-articular loose body entrapment after dislocation. Fibrofatty tissue within the joint (acetabulum pulvinar), septic arthritis and Perthes disease may also give similar findings. 

In the young, two congenital lesions are noteworthy (1) entrapment of the popliteal artery, causing calf claudication with walking but not with running, and (2) adventitial cystic disease of the popliteal or femoral arteries (62-65). Both warrant surgical repair. 

Entrapment of the femoral nerve is a rare condition resulting from a variety of space-occupying processes in the iliacus compartments, such as hematoma, iliacus abscess, iliopsoas bursitis or iatrogenic complications after vessel cannulation, during fracture fixation with metallic plates or inguinal hernia repair. In severe neuropathy, wasting and weakness of the quadriceps muscle, a reduced knee reflex and... 

Femoral nerve (entrapment) at the inguinal ligament level... 

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