[The hemophilic femoropatellar joint]

The knee is the joint most frequently involved in haemophilia. Femoro-tibial damage in chronic arthropathies has been perfectly described. By contrast, lesions of the patella (with the exception of "squaring") have been reported in only a few scanty publications. An attempt was made to define the characteristics by clinical and radiological study (including in addition to lateral films, an analysis of 30, 60 and 90 degrees axial views, even though these were often made difficult by flexion deformity and joint limitation). Femoro-patellar involvement was seen to be very frequent with various lesions: rarely "squaring", and more often patellar erosions or femoro-patellar incongruence (either pre-existing dysplasia or secondary to haemarthrosis) and sometimes actual incarceration (described as "locked patella" by anglo-saxon authors). These concepts are left to have practical consequences in the management of physiotherapy, synoviorthesis and surgery.