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Information for Patients Patellofemoral (Kneecap) Realignment DMI ref: 1992-07.indd(RP) Department of Orthopaedic Surgery Tel: 01473 702107 Issue 1: August 2007 © The Ipswich Hospital NHS Trust, 2007. All rights reserved. Not to be reproduced in whole, or in part, without the permission of the copyright owner. Page Further information is also available in the separate Patellofemoral (Kneecap) Problems booklet. The patellofemoral joint The patellofemoral joint of the knee is formed by the kneecap (patella) moving up and down a smooth groove on the front of the thigh bone (femur). This groove is called the trochlea. The moving surfaces of the patella and trochlea are covered with articular cartilage, which provides a smooth and cushioning joint surface. The patella is held within the trochlea by two tendons. The quadriceps tendon passes upwards from the top of the patella and joins the quadriceps muscle (the main muscle at the front of the thigh). The patella tendon passes downwards from the bottom of the patella and attaches to a bump on the front of the tibia called the tibial tuberosity. Why is a patellofemoral realignment performed? A patellofemoral realignment is performed to correct maltracking of the patella. Maltracking occurs when the patella does not glide evenly within its groove. This produces pain, clicking and sometimes the knee gives way. Patellar maltracking is also known as patellar subluxation. The most extreme form of maltracking is a dislocation. In a dislocation the patella comes out of its groove completely. This can either be due to an injury or it can happen spontaneously. In some people further episodes of dislocation can happen (known as recurrent dislocation). Page What causes patellar maltracking? Certain features can alter the normal mechanics of the knee: • Weakness of the quadriceps muscle • A high patella • A lateral (off-centre) tibial tuberosity • Stretched medial tissues (the capsule and ligaments on the inner side of the knee) • Tight lateral tissues (the capsule on the outer side of the knee) Who should consider a patellofemoral realignment? The following patients may be suitable for a patellofemoral realignment operation: • Patients who have had recurrent (repeated) dislocations of the patella. • Patients who have subluxation of the patella (maltracking of the patella which makes the knee give way) • Patients who have anterior knee pain with maltracking Surgery is not indicated for anterior knee pain with normal patella tracking. What are the alternatives to a patellofemoral realignment? The surgical and non-surgical alternatives are described in our separate booklet Patellofemoral (Kneecap) Problems. Page What is a patellofemoral realignment? A patellofemoral realignment operation involves some or all of the following: 1 A ‘lateral release’ of the tight capsule on the outer side of the patella. 2 The tibial tuberosity may be moved sideways, downwards and forwards as needed (known as a TT transfer). The tuberosity is then fixed in its new position with a screw. 3 A ‘VMO advancement’ is performed to move the inner part of the quadriceps muscle across the patella to improve its mechanical efficiency. Alternatively, a MPFL reconstruction may be performed to replace the ligament which is commonly torn when the patella dislocates. 4 Patella chondroplasty: any rough areas of joint surface are shaved smooth. Rarely, a trochleaplasty is performed to deepen an abnormally shallow trochlea groove. Following a patellofemoral realignment operation, the recovery takes several months and a specific rehabilitation programme will need to be followed. If a TT transfer has been performed then the screw fixation will need to be protected by limiting knee movement in a knee brace. A diagram illustrating the various steps involved in a patellofemoral realignment operation. TT = tibial tuberosity. VMO = inner part of the quadriceps muscle. Page What are the benefits of having a patellofemoral realignment? 1 A stable knee. The patella tracks more normally and should not dislocate. 2 Less pain. A patella that tracks more normally is likely to be less painful, although some pain may persist, depending on the extent of any damage that has already happened. A patellofemoral realignment operation is generally a very successful operation in preventing further dislocation of the patella: 95% (or 19 out of 20 patients) will never dislocate again. Patients with anterior knee pain and maltracking typically have a 75% chance of a good outcome. In other words, three out of four patients have good relief of their symptoms of anterior knee pain and giving way. Your surgeon will discuss your injury and the treatment options with you. However it is your decision whether or not to have surgery. What are the risks of having a patellofemoral realignment? Some of the risks are listed below. Although there seem to be a large number of possible risks, the chance of a significant problem is less than 10% (one patient in 10). Medical problems The risk of developing a major illness, such as a chest infection, is uncommon after a patellofemoral realignment. Blood clots (DVT and PE) Following surgery to the legs blood clots can form in the deep veins of the calf or thigh (deep vein thrombosis or DVT). This usually causes pain and swelling in the calf or thigh. Occasionally part of the blood clot can break free and travel in the bloodstream to the lungs (a pulmonary embolism or PE). A PE can be life threatening but fortunately this is extremely rare after a patellofemoral realignment. Page Infection A wound infection may occur but usually responds to antibiotics. A more serious infection within the knee joint is rare (less than one in 400). Bleeding Some bleeding occurs after any operation. Occasionally a deep collection of blood (called a haematoma) may persist. This usually responds to ice and physiotherapy. Nerve injury A patch of numbness around the scars is usual. The numb area tends to shrink with time. Metalwork irritation Usually the screw used to fix the tibial tuberosity is left in permanently. However, if it is uncomfortable it can be removed. Kneeling discomfort Some tenderness of the scar can cause persistent discomfort on kneeling. Stiffness Over the first few months after surgery it requires hard work and commitment to maximise the movement you gain from your new knee. Moving the tibial tuberosity downwards can tighten the quadriceps muscle and mean that it may be difficult to bend the knee fully. Occasionally the knee can remain stiff. This may be due to excess scarring within the knee, which may require a further operation. Osteoarthritis Some patients develop osteoarthritis (arthritis due to ‘wear and tear’) after a patellofemoral realignment. Usually this is the result of damage to the joint surfaces sustained before the operation. Page What does a patellofemoral realignment operation involve? Before the operation It is advisable to continue a non-operative treatment programme (such as straight leg raises, hamstring stretches, weight loss, etc) as this can help keep your symptoms under control and also help speed up your recovery following the operation. Further details about a non-operative treatment programme are in our separate booklet Patellofemoral (Kneecap) Problems. The operation Usually you will be admitted on the morning of the operation. The operation may be performed under general anaesthesia (when you are fully asleep) or occasionally spinal anaesthesia (an injection of local anaesthetic into the back leads to numbness of the legs). Your anaesthetist will discuss the exact type of anaesthetic with you when you are admitted to hospital. The operation itself lasts about 1-2 hours. Including preparation and recovery, you will be away from the ward for at least three hours. Recovery in hospital Physiotherapy is started as soon as possible after you have recovered from the anaesthetic. If your tibial tuberosity has been moved, you will be fitted with a brace that restricts how far you can bend your knee. The brace will protect the tibial tuberosity until it has healed in its new position (this usually takes 6-8 weeks). Usually the range of movement allowed by the brace will be gradually increased over the weeks. You may also need crutches to help you walk. Most patients will be able to go home within 2-3 days. The wound may be closed with surgical clips or stitched with an absorbable or non-absorbable stitch. The ward nurses will give you advice about your wound before you go home. Page After leaving hospital The discomfort of the operation settles steadily but you may need to continue with pain relief medication for a few weeks. Initially it is normal to have some swelling, bruising and weakness of the leg. The end result depends greatly on your rehabilitation after the operation. You will need to work hard on both regaining the full movement of the knee and building up the strength of the muscles. Your physiotherapist will guide you through a specific rehabilitation programme. The following is a guideline: • First six weeks. Initially you may need crutches to walk. Applying an ice pack for short periods will help reduce any swelling. If you have been fitted with a brace this will restrict how far you can bend your knee. Usually the range of movement allowed by the brace will be gradually increased over 6-8 weeks and you should aim to regain as much movement as the brace will allow. Quadriceps strengthening exercises will be started. • 6-12 weeks. You should be reviewed in the outpatient clinic 6-8 weeks after the operation. If you have been fitted with a brace, you will be allowed to stop wearing this once your surgeon has checked on your x-rays that the tibial tuberosity has healed well. You can then work on regaining a full range of motion and walking normally. You will also start further strengthening exercises. • 12 weeks – six months. Agility work and low-risk sporting activity can begin. Later on you may start sport-specific exercises. Return to work Office workers may be able to return to work after 1-2 weeks. Return to other forms of work should be discussed with your surgeon. Return to driving You may return to driving when it is comfortable and safe. If the right knee has been reconstructed, you must be able to walk without crutches and you must be able to stamp hard on the brake pedal without flinching so that you can perform a safe emergency stop if needed. Page Return to sport You should make a gradual return to full training and competitive sport only when your strength, range of motion and coordination have recovered fully. Your surgeon may recommend some restrictions to your sporting activity. For example, if significant damage to the joint surfaces is seen at the time of surgery, you may be advised to minimise any repetitive weight-bearing involving bending and straightening of the knee (such as running uphill, stair-climbing, stepping exercises). X-rays (side views) of a knee before and after a successful patellofemoral realignment operation. Before the operation (left) the patella is higher than normal. After the operation (right) a fixation screw can be seen. This is fixing the tibial tuberosity, which has been moved downwards to lower the position of the patella. Page 10 Further information If you have any queries, please contact your consultant’s secretary. If you have any concerns during your recovery after a patellofemoral realignment operation, please contact your consultant’s secretary or the ward on which you stayed. They may be contacted via the hospital switchboard on 01473 712233. Page 11 Produced by: The Ipswich Hospital NHS Trust Heath Road, Ipswich, Suffolk IP4 5PD Hospital switchboard: 01473 712233 www.ipswichhospital.nhs.uk