Patella (Knee Cap) Surgery 

Overview

The patella, or kneecap, lies within the quadriceps muscle tendon at the front of the knee. It plays an important role in improving the effectiveness of these muscles in straightening the knee and, perhaps more importantly, stopping the knee from collapsing when the leg takes weight.

With such large forces acting on it, the patella relies on its shape matching the groove on the thigh bone (femoral trochlea) which it runs up and down to provide stability. Any mismatch in shape or position of the patella can cause abnormal forces, poor tracking and resultant inflammation and pain.  Any instability can result in patella dislocation. Surgery aims to improve alignment and patella tracking and provide stability.

Introduction 

Reconstructive surgery to the patellofemoral joint is usually carried out to control recurrent subluxation or dislocation of the patella or to correct maltracking of the patellofemoral joint associated with patellofemoral osteoarthritis. 

Surgery usually includes knee arthroscopy, repositioning of the tibial tubercle (the bony lump below the knee where the patella tendon attaches) to change the position of the patella, surgery to the patella tendon, patella cartilage or reconstruction of the medial patellofemoral ligament. 

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Hospital 

You will be admitted to hospital the day of surgery. You will meet the anaesthetist prior to surgery who will discuss your past medical and anaesthetic history. Surgery is almost always carried out under general anaesthetic. 

After surgery, local anaesthetic is injected around the knee to reduce postoperative pain. A bulky dressing is applied often along with a brace with the hinges locked in full extension. 

After surgery the hinges are set to allow a specific range of motion depending on your surgery. The physiotherapist will then teach you to walk with crutches. You may rest your foot on the ground and take as much weight as you like through the knee provided it is in full extension unless you are specifically told to restrict this. 

Discharge from hospital is dependent on you but can often take place on the same day as surgery.

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Progress 

At the two week check the wound is reviewed by the nurses and a further appointment at six weeks with Mr Howells may include a check X-ray to confirm progression towards union of the transferred bone if performed.

If the radiographs are satisfactory at this stage, the brace is discarded and out- patient physiotherapy is commenced. You may not start isolated quadriceps exercises until the transferred bone is healed in position and this usually takes six weeks. In the intervening time, the physiotherapists in hospital will teach you how to co-contract your quadriceps and hamstrings to safely work the muscles in the first six weeks to minimize quadriceps atrophy but there is usually significant muscle wasting that has to be corrected from six weeks after surgery. 

You may return to an office job 2-3 weeks after surgery but it is usually 3 months before a physical job is possible. A rehabilitation program supervised by your physiotherapist emphasizes range of motion exercises as well as a graduated quadriceps strengthening program to help improve strength and endurance. 

Complications 

The major risks of surgery include infection, blood clots, inadvertent injury to blood vessels and nerves, knee stiffness and recurrent patellar dislocation.

You will be given medication to help prevent infection and clots but it is important to move your ankle up and down a couple of times every twenty minutes whilst awake to help the calf muscle and reduce the risk of clots. If you develop calf or chest pain or un- explained swelling please contact Mr Howells or gain urgent medical review. 

Infection, if left untreated can have serious consequences and it is important to let Mr Howells know if you have increasing pain, a fever, redness or swelling. 

Several major vessels and nerves which supply the leg are in the vicinity of the surgery and are at risk of injury at the time of surgery although this is extremely rare. A couple of small nerves within the skin are often divided at the time of surgery and a small numb patch on the lateral side of the tibia is not uncommon following the surgery. This is usually symptom free. 

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