Patellofemoral realignment surgery is a procedure performed to return the kneecap – or patella – to its normal tracking path when other nonsurgical treatments have failed. It is performed on kneecaps that are suffering from patellofemoral instability, which is the abnormal movement of a kneecap from its normal alignment in the knee.
The aim of the surgery is to realign the kneecap back into the groove and decrease the Q-angle (the angle between the hips and knees). Patellofemoral realignment surgery is broadly classified into proximal realignment procedures and distal realignment procedures.
Differences between proximal & distal realignments
During a proximal patellofemoral realignment surgery, structures that are limiting the movement on the outside of the patella are lengthened, whilst ligaments on the inside are shortened. During a distal procedure, the main aim is to decrease the Q-angle by moving the tibial tubercle towards the inner-side of the knee.
The tibial tubercle is the elevation on the proximal, anterior of the tibia – the larger and stronger bone in the leg below the knee.
How is the surgery performed?
A patellofemoral realignment surgery is performed in an operating room with the patient being under spinal or general anaesthesia. The surgeon will make two or three incisions around the knee in order to insert an arthroscope – a narrow tube with a tiny camera on the end – to view the knee joint.
Using images from the arthroscope as a guide, the surgeon will look for anomalies and repair them using specialised instruments. Depending on factors – like how severe the patellofemoral instability is – a lateral retinacular release may be performed, which is when the tight ligaments on the outer side of the knee are released. This allows the patella to sit properly in the femoral groove.
Causes of patellofemoral instability
Patellofemoral instability occurs when the patella moves either partially – subluxation – or completely – dislocation – out of the trochlear groove. A combination of factors can influence this abnormal movement, including:
- Anatomical defect: Patellofemoral instability can be caused by congenital abnormalities (structural or functional anomalies) – for example, patients with flat fleet.
- Abnormal Q-angle: A high Q-angle can often result in mal-tracking of the patella – for example, patients with knock-knees.
- Patellofemoral arthritis: Patellofemoral arthritis will occur when the articular cartilage has been worn off on the back of the kneecap, which can eventually lead to abnormal tracking of the patella.
- Improper muscle balance: Weak quadriceps can lead to abnormal tracking of the patella, with young active individuals involved in sports activities being more prone to patellofemoral instability.
Diagnosis of patellofemoral instability
A doctor will evaluate the source of a patients patellofemoral instability based on medical history and a physical examination. Diagnostic tests, such as an X-ray, MRI and CT scan may also be performed. A patellofemoral realignment surgery will only be performed if other conservative, nonsurgical treatments fail.
Doctor Julian Lane is a lower limb orthopaedic specialist and is highly experienced in performing patellofemoral realignment surgery. To get more information on patellofemoral instability and methods of treatment, contact the friendly team at Lane Orthopaedic Surgery today on 07 3394 4228.