Suprapatellar Recess

The main recesses of the femorotibial joint are the suprapatellar recess, which is also referred to as the subquadriceps recess, the lateral or parapatellar recesses, located medial and lateral to the patella, and the medial and lateral posterior femoral recesses, which are small recesses that have a close relationship with the internal aspect of the femoral condyles. The suprapatellar recess is the widest recess of the knee joint. It derives from the fusion of the subquadriceps bursa with the joint cavity, a process which occurs during intrauterine life. In normal states, this recess contains a small amount of fluid. 

Clinical demonstration of a knee effusion depends on the amount of intra-articular fluid. Abundant joint effusions can be detected by the patellar tap test in which the examiner first compresses the suprapatellar recess with one hand to squeeze the fluid under the patella and then pushes the patella... 

Fig. 14.17a-c. Prefemoral fat pad. a Coronal 12-5 MHz US image over the suprapatellar recess shows a pseudomass appearance of the prefemoral fat pad (arrowheads) which may become manifest when it is surrounded by an anechoic intra-articular effusion (asterisk), b Coronal Tl-weighted and c fast STIR MR imaging correlation demonstrates a well-defined lobulated mass (arrowheads) which has the same signal as fat surrounded by joint effusion (asterisks). Fem, femur... 

Full-thickness tears of the quadriceps tendon present with complete discontinuity of all tendon layers (Fig. 14.45b). Thelocationofthesetearsisnearly the same as that of partial tears. Occasionally, bony avulsion from the upper pole of the patella occurs (La et al. 2003). In complete intrasubstance tears, US detects two swollen hypoechoic tendon stumps separated by hypoechoic hematoma (Fig. 14.47). The proximal tendon end can be retracted for a variable distance depending on the strength of the musde in general, the distal stump measures 1-2 cm in length (Fig. 14.47). In full-thickness tears of the quadriceps tendon, an intra-articular effusion is almost always seen reflecting a break in the suprapatellar recess. The medial and lateral retinacula should also be... 

Fig. 14.115a-c. Suprapatellar recess intra-articular effusion, a,b Schematic drawings illustrate a the normal suprapatellar recess and b the recess distended by an intra-articular effusion (arrowheads). In b, the fluid contained in the recess (ejf) squeezes (arrows) the prefemoral fat against the femur and displaces the patella anteriorly, c Corresponding lateral radiograph reveals the effusion (Ejf) inside the suprapatellar recess as a mild and homogeneous soft-tissue radiopacity located between the suprapatellar (black arrow) and the prefemoral (white arrow) fat pads... 

Lipoma arborescens (from the word arbor meaning tree in Latin) is a rare benign intra-articular space-occupying lesion characterized by replacement of the subsynovial tissue by mature fat cells giving rise to a villous proliferation which is almost invariably found inside the suprapatellar recess (Ryu... 

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