The suprapatellar pouch (suprapatellar recess) is the extension of the knee joint cavity above the patella (kneecap). Page updated January 2024 by Dr Sheila Strover (Clinical Editor)
This illustration shows the joint cavity filled with fluid, and it gives an idea of how large the joint space is. Generally it is all one big space, with the suprapatellar pouch being the upper part.
Here the knee is cut through the middle. The cavity of the joint is shown in dark grey. You can see that it extends above (suprapatellar), behind and below the patella.
In this illustration it communicates with the rest of the joint cavity, but sometimes a membrane separates it into its own space, which can puzzle the novice arthroscopic surgeon.
Peer-reviewed paperQuote from a peer-reviewed paper:
Citation: Chatra PS. Bursae around the knee joints. Indian J Radiol Imaging. 2012 Jan;22(1):27-30. doi: 10.4103/0971-3026.95400. PMID: 22623812; PMCID: PMC3354353.
If there is too much joint fluid, then the whole pouch can swell up alarmingly like a balloon, and as the fluid is reabsorbed it can lead to the formation of sticky adhesions, which cause the knee to feel stiff, and these can organise into scar tissue, locking the walls of the pouch together and severely limiting movement of the knee.
The pouch may be split into two by a transverse septum, in which case the upper bit - which is now separate from the joint cavity - is called the suprapatellar bursa. Sometimes the septum is there, but is incomplete, and a 'window' exists between the bursa and the joint cavity proper.
If a fold extends right across the cavity, dividing the space into two, then the uppermost part is called a 'suprapatellar bursa' and the fold is called a 'septum' and looks like a membrane stretching right across the pouch. Not everyone has a suprapatellar plica, and a complete septum is rare, but both are considered normal structures unless they get traumatised and interfere with joint mechanics.
Peer-reviewed paperQuote from a peer-reviewed paper:
Citation: Akao M, Ikemoto T, Takata T, Kitamoto K, Deie M. Suprapatellar plica classification and suprapatellar plica syndrome. Asia Pac J Sports Med Arthrosc Rehabil Technol. 2019 Apr 22;17:10-15. doi: 10.1016/j.asmart.2019.03.001. PMID: 31044135; PMCID: PMC6477514.
A patient wants clarification about the X-ray report.
Patients discussing the difference between suprapatellar pouch and septum.