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Understanding Risk Series - Patellar Instability (Kneecap dislocation/MPFL)

It is important to understand the options and risk and complications of surgery:

Patellar instability surgery is performed because of kneecap disfunction and instability when carrying out daily activities and sports. Before moving to the option of surgery it is important to have tried and considered the other non-surgical possible options.

We will examine and determine the instability pattern within your knee and also carry out an MRI scan.

Other alternatives include:

stopping strenuous exercises, work or sports

Losing weight

Physiotherapy and gentle exercises,

Medicines, such as anti-inflammatory

Using a stick or a crutch

Using a knee brace

All surgery and treatment carry some risk these are the most common for patellar instability surgery.

Most Common 2-3% or higher risk of occurring

Pain: the knee will be sore after the operation. If you are in pain, it’s important to tell staff so that medicines can be given. Pain will improve with time. Rarely, pain will be a chronic problem. This may be due to other damage within the knee such as loss of meniscal cartilage, articular cartilage or any of the other complications listed below, or sometimes, for no obvious reason. Some patients can have worse pain after surgery than before that can be permanent. Some patients will regret having surgery and wish they had not proceeded.

Bleeding: A blood transfusion or iron tablets. May rarely be required. Rarely, the bleeding may form a blood clot or large bruise within the knee which may become painful require an operation to remove it (Haemarthrosis).

Blood clots: a DVT (deep vein thrombosis) is a blood clot in a vein. The risks of developing a DVT are greater after any surgery (and especially bone surgery). DVT can pass in the blood stream and be deposited in the lungs (a pulmonary embolism – PE). This is a very serious condition which affects your breathing. We will give you medication to try and limit the risk of DVTs from forming. We will also ask you to wear stockings on your legs and may use foot pumps to keep blood circulating around the leg. Starting to walk and moving early is one of the best ways to prevent blood clots from forming. A DVT may be life threatening.

Knee stiffness: may occur after the operation, especially if movement post-operation is limited. Manipulation of the joint (under general anaesthetic) or a further arthroscopy may be necessary. You may lose some of the flexibility of your knee, in particular loss of hyper-extension or the very deep bend of your knee.

Less Common Risks Less of occurring 1%:

Infection: You will be given antibiotics just before and the procedure will also be performed in sterile conditions (theatre) with sterile equipment. Despite this there are still infections (approx. 1%). The wound site may become red, hot and painful. There may also be a discharge of fluid or pus. This is usually treated with antibiotics, but an operation to washout the joint may be necessary. In rare cases, the ligament and hardware may be removed and replaced at a later date. The infection can sometimes lead to sepsis (blood infection) and strong antibiotics are required. The worst case would be that this infection could be a risk to your life or require you to lose your leg above the knee.

Fracture and Non-Union of the Bone: There is a risk during the surgery when creating small bone tunnels in the kneecap that a fracture may occur. If this happened this may require further surgery to fix the bone back together. This could result in ongoing pain and loss of function as a result. This loss could be temporary and in rare cases permanent. If we carry out a tibial tubercle osteotomy (moving the attachment of the patellar tendon) there is again a risk of fracture. Your body also has to heal the bone and in rare cases this may be slower than normal (6 weeks) or in rare cases even longer. If this occurs, it may require further surgery to encourage the bone to heal.

Ongoing Symptoms: There is a risk that the surgery may not completely resolve your problem and some symptoms of pain or instability may continue to occur. This may require further surgery.

Nerve Damage: efforts are made to prevent this, however damage to the small nerves around the knee is a risk. This may cause temporary or permanent altered sensation around the knee. There may also be damage to the Peroneal Nerve, this may cause temporary or permanent weakness or altered sensation of the lower leg.

Blood vessel damage: the vessels at the back of the knee may rarely be damaged. This

may require further surgery by the vascular surgeons or very rarely amputation.

COVID 19 Risk: It is difficult to quantify at this time the true risk to developing COVID 19 due to your surgery and inpatient stay. We will ask you to isolate before and after surgery. You will also have a COVID 19 swab prior to admission. Despite this there is a risk of contracting COVID. If you did contract it having had surgery and an anaesthetic, you would be at an increased risk of developing breathing complications and this could be a risk to your life.

If you have any questions or concerns, please do not hesitate to contact us before your surgery.

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