KNEE SURGERY

Articles written by
Mr. Fergus Paterson MBBS FRCS (Eng) FRCS (Ed)

ROUGH GUIDE TO THE DIAGNOSIS AND TREATMENT OF COMMON KNEE DISORDERS

Introduction

Most people will at some time or other have had a painful knee resulting from either a skiing injury, a collision on the football field, an inflammatory disorder such as rheumatoid arthritis, gout, etc., or simply a flare-up of pre-existing arthritic change due to advancing years. Medical advice can come from a variety of sources: victims of sporting injuries may see the club physiotherapist or a doctor in the local hospital Accident and Emergency department; whereas the more chronic conditions, including arthritis, will be treated initially by the General Practitioner or Rheumatologist. If the prospect of surgical treatment begins to loom on the horizon then patients should see an Orthopaedic Surgeon who specialises in the knee.

The diagnosis of sporting injuries of the knee is usually fairly straightforward following clinical examination and X-ray. If there is no fracture then it will be damaged ligaments, a torn cartilage, or possibly a combination of the two. Patients with non-sporting knee disorders tend to fall into fairly well defined age groups with children forming a special group of their own. Where a diagnosis cannot be reached after clinical examination and X-ray it may be necessary to carry out further investigations including blood tests, MRI scan, and Technetium 99 bone scan. Ultimately the inside of the knee can be viewed on a TV screen by inserting an arthroscope under anaesthesia (keyhole surgery).

A rough breakdown of knee disorders (sporting and non-sporting) according to age group is discussed within this website, but it should be emphasized that this is only a brief summary and a considerable amount of overlap exists between the two groups.

Childhood (under 10 years of age)

Infection in a bone close to the knee (osteomyelitis) or within the knee joint itself (pyogenic arthritis) is seen much less often nowadays than say fifty years ago, the improvement being due to the availability of antibiotics and better living conditions. Infection can reach a bone or joint following a sore throat or tonsilitis or even an infected skin wound. The classic symptoms of infection in a bone or joint are intense unrelenting pain coupled with a high temperature in a child who screams every time the knee is moved. Such a scenario should alert parents to the possibility of infection and prompt them to seek urgent medical advice. Blood tests will show a high white cell count but in the early stages of infection X-rays may well be normal. Treatment with intravenous antibiotics is usually curative, but if left too long an abscess may develop and require surgical drainage.

Knee pain in children can sometimes be due to problems in the hip joint (referred pain). This possibility should always be borne in mind if there are no local signs to be discovered on examining the knee itself. An X-ray of the pelvis should be carried out in appropriate cases.

Teenagers (10 to 15 years of age)

Osgood-Schlatters disease is a common and harmless 'growing pain' felt at the top of the shin where a tender lump often develops. It is frequently seen in young footballers of either sex and is basically due to excessive activity. Rest from sport for a week or two helps this condition to subside, but intermittent flair-ups can occur until the end of growth when the condition usually cures itself. X-rays are helpful in making the diagnosis and surgical treatment is hardly ever required.

Chondromalacia Patellae is extremely common among teenage girls, indeed it is one of the commonest causes of referral to knee clinics. It produces discomfort around the kneecap (patella) which is typically worse with running, climbing stairs, and sitting still for long periods, and may produce a sensation of crunching or clicking under the kneecap with walking. The exact cause of chondromalacia patellae is poorly understood but it may be related to wearing a shoe with a raised heel or playing a lot of sport. The under surface of the kneecap, when viewed through the arthroscope, looks soft and may be cracked superficially. Although at times a nuisance, this condition is essentially benign and does not go on to cause arthritis. However the symptoms themselves may be difficult to treat effectively. Reassurance is given in the majority of cases but occasionally keyhole surgery can be helpful.

Patella dislocation, where the kneecap (patella) slips sideways round to the outer side of the knee, is both painful and alarming when it occurs. Once again it is commoner in girls and there may be predisposing factors such as generalised joint hypermobility, knock-knees, etc. If dislocation of the kneecap occurs repeatedly the only treatment likely to be effective is surgical realignment of the patella. This operation involves a scar three to four inches long on the outer side of the knee and is followed by immobilisation in a long leg cast for about a month. After that a period of physiotherapy is needed to get the knee moving normally again. Sometimes patella dislocation can occur in both knees and may be associated with instability of other joints, e.g. the shoulder.

Osteochondritis dissecans is when a fragment of joint surface splits off within the knee causing pain and locking. It tends to be seen in the more sporty individuals and causes a persistent nagging pain towards the inner side of the knee, made worse by activity. Examination findings may be few or absent altogether, but X-rays are diagnostic. Treatment in the early stage of the disease is rest; but once a loose fragment has developed it should be removed by keyhole surgery.

Young Adults (15 to 40 years of age approximately)

A torn cartilage (meniscus) is probably the commonest reason for a young adult to seek help from a Knee Surgeon, and the commonest operation performed in this group is keyhole surgery (arthroscopy) to treat it. It's not only sportsmen (and women) who tear a meniscus, plumbers, electricians, and carpet layers are also at risk. Meniscal tears cause pain and often a sense of mechanical interference e.g. locking. Each knee has two menisci (see diagram) which function rather like shock-absorbers protecting the joint from impact forces; it therefore follows that removal of an entire meniscus can predispose to degenerative arthritis years later. Localisation of the pain may provide a useful clue as to which meniscus has been torn. Xrays are of little help in confirming the diagnosis as only the bones will show up. But an MRI scan shows both the menisci and other soft tissues including ligaments. The only sure way to clinch the diagnosis of a torn meniscus is by arthroscopy, and this has the added advantage of allowing the surgeon to deal with the lesion at the same time.

Ligament injuries are the second commonest reason for knee surgery in this group. The knee is held together by four main ligaments, any one or combination of which may be damaged by twisting forces applied during vigorous sport. Injuries vary from a simple sprain (stretching) taking a few weeks to resolve, to a complete rupture which may require surgical repair if permanent instability is to be prevented. The most important ligament of all is the Anterior Cruciate (ACL) which lies in a pivotal position at the centre of the joint controlling rotation (see diagram). Unfortunately a ruptured ACL will not heal by itself and renders the knee liable to give way with turning movements causing sudden pain followed by swelling. In the longer term an untreated ACL rupture is associated with an increased incidence of meniscal tears and osteoarthritis. It is therefore often necessary to consider surgical reconstruction particularly in athletes.

ACL reconstruction is a highly specialised procedure and not for the occasional performer. The torn ligament has to be replaced by a graft made from hamstring tendons or the patella tendon and is best done using a keyhole technique. Postoperatively it is vital that a properly supervised rehabilitation programme under the direction of a physiotherapist is adhered to. The overall results of ACL reconstruction are successful in well over 90% of cases, patients should be able to return to non-contact sport after three months from surgery and contact sport after six months. For an elite sportsman (e.g. Paul Gascoigne or Roy Keane) it usually takes a year to regain match fitness.

Older Adults (over the age of 40 years)

Wear and tear changes are bound to develop in all weight-bearing joints as part of the ageing process but they can be accelerated by previous injury, for example a fracture involving the joint surface. When such changes become clinically significant the condition is called osteoarthritis (OA). In the knee OA causes recurrent bouts of pain and swelling leading eventually to a degree of permanent disability which may seriously affect walking. Treatment in the early stages will probably be a mixture of tablets (e.g. Brufen or Voltarol.) supplemented where necessary by physiotherapy. If these simple measures fail to bring relief then an arthroscopic washout may be helpful for a limited period. End-stage OA can only be treated effectively by joint replacement surgery (TKR)(see photographs below).

First Image: During Surgery for Knee Replacement

Second Image: Lower End of Arthritic Femur Showing Eroded Joint Surface

Third Image: After Knee Replacement

Fourth Image: Knee Replacement from second image

In the U.K. alone approximately 30,000 total knee replacements are performed each year, with a success rate of well over 90%. Patients undergoing TKR will spend about 10 days in hospital - most of which is for physiotherapy - and at the end of this time be able to return home and cope independently. Confidence with walking will continue to improve over the next few weeks and driving a car should be possible a month from the operation. A round of golf may take a little longer !

A successful knee replacement should give good service for at least ten years. If it should fail for any reason the it can usually be done again.

For more information or advice please see Mr. Fergus Paterson's website which can be located at http://www.knee-surgery.co.uk