Arthritis is a condition affecting joints of the body and involves the destruction or loss of the lining (articular) cartilage of the joint. It is usually a degenerative condition associated with ‘wear and tear’ and a normal part of ageing.
The most common type of arthritis is degenerative osteoarthritis, the incidence of which increases with age. There are however, other types of arthritis which are generically termed inflammatory arthritis and include conditions such as rheumatoid arthritis and other connective tissue related arthropathies. The knee is the largest synovial joint in the body and is commonly affected by arthritis as is the hip and the ankle, as well as the foot. Arthritis is more common in weight bearing joints and so is more frequently seen in the lower limb than the upper limb. Arthritis can run in families, but is not specifically genetically predisposed. Arthritis of the knee is more common in people who expose their joints to repetitive micro-trauma, of which weight bearing is a simple example. This will slowly overload the joint, especially if the person is overweight. It is thought that people involved in many years of sports, that include running, twisting and jumping can also be predisposing themselves to an increased risk of arthritis in future years. There is no doubt that various types of acute trauma to the knee, such as fractures, dislocations and major ligament injuries, as well as direct damage to the lining (articular) surface of the knee joint, can lead to accelerated arthritis development in the years to come.
Normal alignment of the lower limb results in weight bearing forces of the body going through the medial (inner) compartment of the knee. Therefore medial compartment arthritis is the usual starting point for knee arthritis as this is the compartment that is being continually loaded.
Any condition that changes the loading pattern and alters the mechanical axis of the leg can result in arthritis distribution in other compartments of the knee. This can occur in fractures which heal with malalignment or even with removal of meniscus tissue which will result in increased force being put through the articular cartilage in the affected compartment.
The increase force applied to the articular cartilage over time causes breakdown of the articular cartilage and the development of arthritis.
Not all people with arthritis have symptoms. Arthritis, as stated previously, is an age related phenomenon, and therefore the incidence increases with age, but the mere presence of ‘arthritic’ type changes on x-ray does not equate with symptoms.
The symptoms that patients will commonly complain of with arthritis include pain, swelling and limitation of activities. As the arthritis gets worse, so the symptom severity will increase. Initially pain may only occur during walking, but eventually rest and night pain is not an uncommon feature. This can lead to one of the other key clinical assessment tools of arthritis severity which is that the patient will complain of an ever decreasing walking distance before the pain will come on.
The swelling is usually related to inflammation, but can also be due to mechanical factors such as loose pieces of articular cartilage or even bone floating within the knee, or degenerate associated meniscus tears.
The clinical assessment of a patient with knee arthritis, involves taking a detailed history which will include
- Location of pain.
- Severity of pain.
- When the pain comes on – activity related, rest pain or night pain.
- Swelling of the knee.
- Walking distance.
- Activity restriction due to symptoms.
- The type of analgesia/anti-inflammatories used and their effect on the symptoms.
- The effect of any previous treatment that has been given – for example physiotherapy or injections.
- Any history either in the individual or the individual’s family of inflammatory arthritis or gout.
The next step is to examine the knee joint as well as assessing the hip joint and the lumbo-sacral spine both of which can cause radiating pain to the knee.During the examination, the patient’s gait (walking pattern) is assessed and any deformities of the knee in all the planes are documented.
Investigations for arthritis usually entail weight-bearing radiographs of the knee and also a long leg standing alignment x-ray of the leg to show the axes of the leg and knee.
AP x-ray of the knee showing gross lateral compartment osteoarthritis with total loss of lateral joint space.
AP x-ray of the knee showing early medial compartment osteoarthritis with mild medial joint space narrowing.
The treatment for arthritis depends on its symptom severity. Outlined below is a typical treatment algorithm, which treats fairly minor symptoms all the way to end-stage arthritic disease.
Weight loss. The knee joint can take up to eight times your body weight, depending on activity and therefore reduction of body weight can have an up to eight-fold effect on reducing the loading forces that are crossing the knee joint, which will then potentially reduce the pain arising from the arthritic part of the joint.
Regular non-impact loading resistive exercise programme. There is some evidence that the symptoms from arthritic disease can be reduced by undertaking a regular non-impact loading exercise programme. The aim of the exercise programme is to strengthen the muscles around the knee, including the calves, hamstrings and quadriceps, as well as stretching the knee joint and surrounding muscles. The recommended exercises are non-impact loading ones, such as swimming, cycling, using a cross-trainer and some light resistive weight training exercises. These exercises do not reduce the actual arthritic disease, but can help with symptom control.
Non-steroidal anti-inflammatory drugs. This is a group of medicines which reduce inflammation and therefore will reduce pain and swelling. Drugs in this class include Aspirin, Ibuprofen, Diclofenac and more recently the Cox II inhibitors, such as Celebrex.
Analgesia. In addition to the anti-inflammatories, regular analgesia can be taken, including Paracetamol and Codeine based drugs. These work in combination with the anti-inflammatories and are more effective synergistically than when taken on their own.
Walking sticks. Using a walking stick in the hand opposite to the affected knee will off-load the painful joint and therefore once again will reduce symptoms from that joint. It is an effective technique that is commonly used.
Physiotherapy. The aim of physiotherapy is to stretch any contractures and to increase the range of motion of the joint, as well as to work on a strengthening programme. In addition to this, physiotherapy modalities such as ultrasound, mega pulse, interferential and ice can be used to control swelling and pain. The effectiveness of physiotherapy is variable, but is certainly worth trying prior to any surgical interventions.
Hyaluronic Acid injections. Hyaluronic acid is a normal constituent of any synovial joint, including the knee joint. It is well known that synovial joints that have arthritis produce less Hyaluronic acid than normal joints. The aim of the Hyaluronic acid treatment is to increase the concentration of Hyaluronic acid within the joint and to stimulate the knee to produce more Hyaluronic acid. It has been shown that intra-articular injections of Hyaluronic acid do stimulate long term Hyaluronic acid production and so maintain increased concentrations in the knee. The injections usually involve a course of three to five injections into the knee joint. (Link to Hyaluronic acid mechanism page).
Intra-articular steroid injections. Injecting a knee joint with a steroid can reduce the symptoms from arthritis, including pain and swelling. A steroid is a potent anti-inflammatory drug, and by injecting it directly into the knee joint, it acts locally with little systemic absorption. The common fears of steroid usage and side effects from this are related to systemic absorption of the steroid into the body, but by injecting steroids into the knee joint, the risks of side effects outside of the knee joint, in the body, are low. Steroids are an effective treatment option and will reduce pain and swelling. However it is usually a temporising phenomenon and the symptoms can return. Steroid injections can be repeated, but usually no more than two to three per year should be given. In my practice, I tend to reserve steroids for people with more advanced arthritis.
Glucosamine /Chondroitin Sulphate. This is a combination of drugs that are commonly used by people with arthritis. The original studies that were done on this drug combination produced results showing that articular cartilage could be regenerated by the use of this drug. These studies were however, undertaken in animals including dogs and rabbits. Animal articular cartilage is different from human articular cartilage in that it has a regenerative capability which human articular cartilage does not have. However, there are some recent clinical studies, which suggest that there may be some symptomatic benefit from using Glucosamine and Chondroitin Sulphate.
Interleukin I receptor blockers. This is potentially an exciting group of drugs which work by blocking Interleukin I. Interleukin I is a pro-inflammatory substance which promotes inflammation and the inflammatory molecule itself can cause the further breakdown of articular cartilage. Therefore by blocking this naturally occurring substance, it can reduce the physical and symptomatic effects of arthritis. There is some research work to suggest that it may even potentially reverse some of the arthritic destruction of the joint and so the x-ray appearances of arthritis, although this does require more study. These drugs are not yet licensed in the United Kingdom , but no doubt will become available soon.
Arthroscopic debridement and washout. This is a surgical technique involving a knee arthroscopy, which is undertaken with the intent to remove any mechanical problems within the knee such as loose articular cartilage flaps, degenerate meniscal tears or any loose bodies. Degenerate areas can be “tidied up” and the bone can be perforated by drilling or microfracture to cause bleeding and subsequently scar tissue infill to promote some degree of shock absorbing function back. However the tissue produced is not normal articular cartilage. The results of arthroscopic debridement are much better if the person demonstrates mechanical features in their knee, such as swelling, localised joint line pain or locking. Once again the effect of arthroscopic debridement tends to be temporary, but can last many months or even years. (Link to microfracture).
Articular cartilage transplantation. This is a technique that has been described for traumatic articular cartilage defects (below), where articular cartilage cells are actually taken from your knee and grown in a laboratory. The cells are then returned and are, at a second operation, re-implanted back into the knee, with the theory that normal articular cartilage is produced. The early short and medium term results in traumatic defects, is certainly promising. As our experience with this technique improves, the indications for it are also widening. It is a technique that I am now starting to do in people with localised articular cartilage degenerative disease, but certainly not in end-stage, bone on bone arthritis. The technique may be required to be done in combination with other procedures such as osteotomies about the knee.
Osteotomies. Osteotomy is a term used to describe the surgical breaking of bones. The osteotomies about the knee can be done in the femur or the proximal tibia, depending on the type of arthritis. The aim of this treatment is to re-align the mechanical axis of the limb so as to move the mechanical axis from the arthritic compartment to the normal compartment of the knee.
Unicompartmental knee replacement. Knee arthritis in the early stages can involve only one compartment of the knee such as the medial compartment, the lateral compartment or the patello-femoral compartment. If the arthritis and symptoms are truly related to one compartment, then it is much more logical to treat that affected compartment and leave the other compartment of the knee alone. In this situation, In this situation a unicompartmental knee replacement can be undertaken. Most commonly, this will involve the medial compartment of the knee. However, isolated patello-femoral (knee cap) knee replacements can also be performed if the arthritis pattern is localised to the knee cap joint. The advantage of unicompartmental knee replacement is that it is a less invasive operation. It has a much quicker recovery period. There is less post-operative pain. There is less bleeding. The length of hospital stay is shorter. The range of motion achieved is usually greater. These comparisons are all made in relation to total knee replacements. The potential downside of unicompartmental knee replacement is that if arthritis and symptoms develop in the other compartments of the knee, then further surgical replacement may be required.
Total knee replacement. Total knee replacement is the mainstay of treatment for end-stage arthritis or symptomatic arthritis that does not respond or is unsuitable for the above-mentioned previous treatment options. It is a highly successful operation when performed correctly, with a greater than 95% success rate. It is however a major operation, and does have some potentially serious complications, which must be weighed up against the benefits before a decision is made to undertake total knee replacement surgery. Minimally invasive knee surgery is now a procedure that I now routinely perform which has the added benefits of quicker rehabilitation, shorter hospital stay and less pain in the short term, allowing a quicker return to function.
Arthrodesis. Arthrodesis means fusion, which in this context relates to fusing or stiffening the knee joint. This is usually performed with the knee in a slightly bent position. Since the advent of knee replacement surgery, a primary knee arthrodesis for arthritis is practically unheard of. It is however, occasionally done for complications of knee replacement surgery such as resistant infection.