What is it ?
During an accidental movement, the patella may dislocate, i.e. become dislocated, and sometimes remain unstable afterwards.
Patella pathology
Dislocation and instability of the patella
Clinical presentation
During the first episode of patella dislocation, the pain is sharp and the knee is blocked if the patella remains dislocated, it is then necessary to perform a manoeuvre to reduce the patella (succeed in stretching the patient’s knee and the patella will reduce spontaneously or by accompanying it), A joint effusion generally consisting of a hemarthrosis or lipo-hemarthrosis follows, testifying to the tearing of the MPFL (medial femoropatellar ligament) which stabilizes the patella and to bone contusions between the patella and the femur. After a first episode of patella dislocation, the patient is 6 times more likely to dislocate the patella again. Subsequent dislocations are often less impressive and less painful.
When to consult a specialist?
It is recommended that an emergency centre or orthopaedic surgeon be consulted immediately after a first patella episode to perform X-rays and MRI to exclude lesions that would require emergency surgery (e.g. osteochondral fracture of the patella). An orthopaedic surgeon should be consulted after the second episode of dislocation to analyse the predisposing factors to patella dislocation and to determine whether or not surgical management is necessary, as each additional dislocation may create or aggravate damage to the patella cartilage.
Non surgical treatment
Always indicated after a first episode of patella dislocation, it aims to stimulate the muscles that are the dynamic stabilisers of the patella, notably the quadriceps. Physiotherapy is essential after a first episode to recover joint mobility of the knee, to awaken and strengthen the muscles, to work on balance and dynamic control of the patella, and to reduce the fear of a new dislocation.
Surgical treatment
The surgical treatment is done “à la carte”, i.e. each morphological factor predisposing to patella dislocation is analysed and treated: the MPFL is reconstructed by an autograft (with the help of the gracilis tendon or a strip of the quadricipital tendon), the patella is recentred and repositioned if necessary (according to the analysis of the TAGT and patellar height) by a medialization and/or distalization osteotomy of the anterior tibial tuberosity
Postoperative follow-up
Following this type of operation the patient walks for 4-6 weeks on crutches with partial weight-bearing and wearing a jointed splint. Physiotherapy is started the week after the operation.
Risks and complications
Surgical treatment aims to stabilise the patella and prevent further dislocation and surgery guarantees this result, however it is possible that pre-operative pain does not disappear completely with surgery. The scars that are made may cause superficial sensitivity problems around the scars.