Patella dislocations are common in childhood and early adulthood. They are usually caused by an injury, but a large percentage of people who develop patella instability have predisposing problems. Patella dislocations can be classified as Traumatic single events, Recurrent or Habitual. Acute or traumatic are the most common types of dislocation. Some of these reduce spontaneously, while others require management in the Emergency Department.
Xrays and an MRI are usually taken after a Traumatic Dislocation, in order to establish that there are no other injuries in the knee and to rule out associated Osteochondral fractures. These can occur on the medial aspect of the patella and the lateral femoral condyle. They may need removal or internal fixation depending on the size and position of the fractures.
Following reduction of an acute dislocation, rest, ice and then a physiotherapy program is needed. Up to 50% of traumatic dislocations go on to Recurrent dislocations. Often there are predisposing factors such as family history, generalised ligamentous laxity, lower limb malalignment, or abnormalities of the patella-femoral joint (patella alta, small patella, flat patella facets, shallow femoral groove)
Recurrent patella dislocations often require further investigations with Functional CT scanning.
Management must be carefully considered in this type of patella dislocation. Physiotherapy is always required. A patella stabilising brace or taping may be useful. Surgery is considered when there has been 3 or more dislocations or episodes of instability. Surgery is tailored to the age of the patient and the above factors that have led to the dislocation in the first place. The options are: Initial Realignment Procedures, Medial Patello-femoral Ligament Reconstruction, Tibial Tubercle Transfer or Trochleoplasty. It is very important to carefully consider all options before deciding on treatment.