Osteoarthritis (Of the Knee Joint)
Introduction
Osteoarthritis (OA) is an ancient disease which dates back to the Neolithic period and is also the most common form of arthritis. Perhaps also indicates the reason for the use of this particular name which actually means inflammation of the joints, whereas OA is a non-inflammatory, degenerative disease of the movable joints. This means that the disease worsens with the passage of time, and age is an important risk factor for this particular disease. Degenerative joint disease or Osteoarthrosis would fit to the disease pathologically. To summarise OA may be defined as a slowly progressive disease of monoarticular joint with no known cause.
It is a relatively common disease in the elderly population as the most important predisposing factor is age. According to C.M.Stein and G.Taylor (2004), 80% of people at the age of 65 years will have radiological proof of OA but maybe 10% of these will actually present with some sort of symptoms like pain and loss of range of motion. Before the actual clinical presentation of symptoms, the disease is reversible if the factors initiating the disease are corrected. At an age of less than 50 years more males are affected than females but beyond 50 years more females are affected indicating a hormonal relationship with the condition. Genetic mechanical and hormonal factors are being demonstrated by Ghosh P, Cheras PA (2001). There are recent studies by Sheng-Yu Jin et.al (2004) which predicts the association of ER*- α* gene haplotype with primary knee OA in the Korean population, and that genetic variations in the ER- * α* gene might play a role in susceptibility to OA.
!http://www.indmedica.com/cyberlecturespics/22605_osteoknee.png”(comparison of Healthy knee and Osteoarthritic knee)!
Figure 1 compares normal knee joint with osteoarthritic knee joint.
Pathophysiology
When two bones meet at a point called the joint, some form of cushion is required to protect the end of the bones from trauma against each other. So the joint line is covered by this flexible and smooth form of connective tissue called Cartilage to absorb the shock which arises when two bones come closer as in heel strike during the stance phase of the gait, climbing down stairs ect. The cartilage is four layered with a thickness of about one-eighth of an inch, lacks blood supply and nerve supply but one of the layers mostly contains a complex molecule known as the proteoglycans which has the property of holding the fluid around the joint to keep it lubricated by the synovial fluid. (R.H.Phillips 2001)
When the catabolism by Collagenolytic enzymes exceeds the anabolism the result is osteoarthritis. Usually the first changes are seen in the cartilage in the form of fibrillation due to the advance in age, which may be seen microscopically but the visible abnormality is a local swelling in the matrix of the cartilage. At the cellular level, the chondrocytes surrounding the matrix increase in number than the normal but the general layout is same as the normal. There also occurs a deposition of fine fat molecules in between the matrix which may increase in size at the chondrocyte capsule. This particular condition, though degenerative, also involves new bone formation at the joint surfaces which is the Remodeling in response to the disease process, resulting in changes in the shape of the joint with age, the varus deformity of the knee. In relation to the joint line there are two places where new bone formation occurs i.e. at the margins, called the marginal osteophytes, and at the part adjacent bone marrow. It is these marginal osteophytes which travel to the joint space and limit the range of motion in one pattern of growth. In the second pattern the osteophytes develop in the soft tissue attachments to the joint causing an inflammatory response, ultimately giving rise to pain. The degeneration of the joint cartilage also gives rise to Eburnation, a phenomena in which the bone becomes smooth and shiny due to loss of cartilage and constant rubbing against each other giving rise to crepitus. This describes the major signs and symptoms of this condition which are pain, limitation or range of motion, crepitus and deformity.
A history of trauma around the knee joint, or injury to the anterior cruciate ligament showed an increase in incidence of degenerative changes. This may explain that altered biomechanics can initiate damage to the joint cartilage though the cartilage has the ability to structurally adapt to the loading of the joint.
Evidence of Exercise as a Conservative Treatment
Inactivity produces and progresses the signs and symptoms associated with arthritis, namely muscle weakness and atrophy, decreased flexibility and cardiovascular fitness, osteoporosis, depression and lowered pain threshold. Surgical treatments are the final therapeutic procedures to overcome the disability caused by OA knee but are not the ideal method as it increases the risk of other forms of illness, blood loss, hospital stay and prolonged rest to the joint postoperatively. The surgical options include:
- Arthroscopy
- Osteotomy
- Arthroplasty
Non-surgical therapy of knee OA often focuses on a pharmacological approach and includes analgesic agents or non-steroidal anti-inflammatory drugs (NSAIDs) . This type of therapy may imply serious health hazards because of adverse gastrointestinal effects. Overweight, and especially obese, persons run a high risk of OA in the knee and probably also the hips and hands, although the mechanism by which obesity causes OA is poorly understood .
According to Greene.B and Samlin.S (2003) exercise is “systematic and planned physical movements or physical activities to prevent further damage, promote functions and enhance the level of fitness and well-being”. Exercise increases the mobility of joint, releases endorphins, and may help to reduce weight in conjunction with a low calorie diet. Fitzgerald PL (1985) and Ike RW et al (1989) show that there may be a significant deceleration in the disease process if a healthy lifestyle is incorporated which takes into account healthy eating appropriate to the body composition, and exercise training.
The load on the knee joint can either be reduced by reducing the overall weight of the individual or increasing the muscle mass of the quadriceps and the hamstring muscles which provide the support to the joint. In the past it was believed that rest would benefit inflamed joints and promote healing. However, recent studies have shown that people with OA of the knee can tolerate weight-bearing exercise such as walking. In fact, studies show great benefits in exercise for people with OA. A trial done for 18 months by Messier et.al (2004) found that exercise in conjunction to a low calorie diet produced significant decrease in morning stiffness and increase in physical activity level
In a randomized control trial of 439 adults living in community with knee OA O’Reilly SC, Muir KR, Doherty M (1999) compared groups that had 18 months of aerobic walking with programs of resistance exercise and of health education. Both exercise groups improved in physical performance, knee flexion strength, and decreased pain compared to the education group. The study of outcomes by percentage of sessions performed showed significant improvements in disability, pain and walk scores associated with increasing compliance.
A consequence of osteoarthritis knee there occurs limitation in the range of motion and lack of strength. The main clinical presentation of OA knee is varus deformity and grade 1 laxity of the lateral collateral ligament. So the goal should be to strengthen the muscles and tendons of hip abductors and stretching the hip adductors and this is brought about by placing the resistance on the knee rather than the ankle. During the later stages of the disease the goals should concentrate to increase the strength, range of motion, functional capacity including balance and co-ordination to prevent falls due to knee instability, and prevent osteoporosis due to non weight bearing. Activities such as stepping, resisted exercises of the knee joint, swimming, cycling, and walking should be emphasised.
Knee strengthening exercises should involve supervised exercise protocol (S. B. King, M. A. Minor 2003) for 5 weeks at a frequency of two times a week, a duration of 30 mins and the volume of 8-10 exercises; 8-12 lifts of a load of 60-80% of 1RM to produce local fatigue in 8-12 repetitions; 1-3 sets as tolerated, maximal isometric knee extensions of 24 repetitions, stationary bicycling at a moderate speed for 2 mins and functional exercises for 1-3 mins. After 5 weeks of supervised exercise protocol, home exercises for functional independence must be prescribed 2-3 exercise at a frequency of 3 days per week.
Along with particular knee exercises, emphasis should also be towards maintenance of the cardiovascular fitness and include aerobic exercises at a frequency of 3-5 days per week at 60-80% maximum heart rate for duration of 20-60 mins continuously. Range of motion exercises in the form of gentle stretching and full range flexion and extensions should be done daily to improve and maintain the full range mobility at the knee joint. Due to the laxity of ligaments around the joint there occurs instability of the knee joint leading to an increase in falls. To overcome this balance and co-ordination exercises must be incorporated in the form of line walking with or without support depending on the level of independence, tilt table exercises, and body awareness training.
As there is a strong relation between obesity and OA knee efforts must be made to loose weight and maintain a recommended BMI especially for women as they tend to be more susceptible to OA knee. For this low intensity long duration exercises at 50% of the maximum heart rate must be administered till the target weight is achieved. Interventions such as walking for 60 mins on a treadmill or on plain surface, swimming, along with a low calorie high fibre diet can be administered as exercise alone can not produce the desired effects.
Contraindications to Exercise Therapy
The acute stage of the disease is usually associated with local inflammatory changes such as local rise in temperature, swelling and pain during weight bearing. Therefore care must be taken to avoid any resistance training during this phase of the disease and emphasis on prevention of deformity. Although isometric knee exercise every day at a frequency of 5 contractions per hour, and slow rhythmic mid range dynamic free movements can be performed depending on the level of pain. Care also is taken not to over exercise as it may lead to delayed onset muscle soreness and increase the level of pain. Walking without support must not be attempted during this phase as it may result in falls due to instability. Even a slight stumble may result in micro trauma to the ligaments surrounding the knee joint. Stair climbing and walking on elevated tread mill or uphill should also be discouraged as it may increase the level of pain.
Exercise is also strongly contraindicated if co-morbidity in the form of cancers (malignancies) and severe cardiovascular diseases, in the form of malignant hypertension or aneurysm ect. exists. Any undertaking of an exercise program should be consulted with the physician. Therefore a pre-exercise screening must be performed to rule out any hazards.
Barriers to Exercise Participation
The physical barriers to exercise participation in OA knee is the pain and stiffness. This can be reduced by application of heat or cold before the exercise program. Heat induces local relaxation of muscles, release endorphins and blocks the pain gate thus reducing pain and stiffness.
Other barriers to exercises are the cost of visiting a physical therapist or a trainer for the whole exercise program. The cost of physical training can be reduced considerably by teaching the exercise, frequency and duration at one visit and instructing the patient to continue the exercises at home.
A psychological barrier to exercise is when the patient feels that exercise may worsen his/her condition. Proper education on osteoarthritis by self help courses and web site e.g. http://www.arthritis.org ; (telephone: 888-879-7890) can provide the necessary information. A study done by K R Lorig and colleagues in 1985 demonstrated that monthly telephone communications with patients were cost-effective and were associated with good clinical outcomes. In this way patient education can help them to participate actively in exercise programs.
Lastly motivation of the patient towards any exercise program may pose a barrier. The motivational status may be improved by group therapies including a number of patients with OA knees so as to socialise within group and compare the level of disabilities.
Ms Annapurna Chandani,
B.P.T (India) Msc Exercise Science, (U.K)
Physiotherapist (IAP Reg No.9636)
B.P.T (India) Msc Exercise Science, (U.K)
Physiotherapist (IAP Reg No.9636)
