The knee cap, known as the patella is a floating bone and serves to attach the large and powerful thigh muscles (quadriceps) to the upper part of the lower leg bone (tibia). Under normal circumstances, the patella sits in a shallow groove at the front of the knee and as we flex and extend our knees when performing tasks such as stairs and squatting the patellar slides freely up and down in this groove.
Instead of a deep socket to maintain the stability of the joint the knee cap joint (patellofemoral joint) relies on the quadriceps muscles and surrounding soft tissue for this role. Due to the huge forces that this joint (patella-femoral joint) experiences with every day and sports related movements this stability can sometimes be compromised with a traumatic patellar dislocation.
In other circumstances, the patellofemoral joint may be unstable due to inherent, developmental factors. Examples may be a more shallow groove for the patella to sit in or very flexible soft tissue structures in individuals with hypermobility syndrome.
Depending on the underlying cause of the patellar instability, patellar stabilisation surgery can be performed in a number of ways. One part of the surgery will often involve tightening up the stabilising soft tissue structures on the inside of the patellar. This can help to prevent the patellar from dislocating sideways in the opposite direction (laterally).
Another part of the surgery can be simultaneously releasing some of the structures towards the outside (lateral) aspect of the patellar. This will be considered if these structures are considered too tight and the release can prevent excessive pulling of the patellar laterally which can lead to dislocation.
In many cases surgeons will also move the insertion point of the patellar tendon further towards the inside of the knee. This part of the procedure is termed a tibial tuberosity transfer. This positions the patellar further towards the inside of the patellofemoral joint groove leading to less chance of dislocation.
Depending on the exact surgery undertaken it is normal for patients to be placed in a brace for the initial four to six weeks after surgery to allow only limited amount of bend in the knee. Patients may also be non weight bearing or partial weight bearing for a period of time. This is to allow the bone to heal if a tibial tuberosity transfer has been performed and to allow the soft tissue tightening to heal.
Once these restrictions have been lifted, Circle Health monitor our patients regularly with our specialist physiotherapists who are able to create comprehensive rehabilitation packages for our patients to return to activities of daily living and sports as appropriate.