What is Osteoarthritis?
Osteoarthritis (or OA for short) is the most common type of arthritis and is associated with joint pain and reduced range of motion and quality of life. It is a vast, chronic condition which affects the weight bearing joints and involves biomechanical, morphologic and biochemical alterations of the matrix and cells of the bone. Common symptoms are pain in the affected joint area and loss of mobility however, structural changes may occur without any accompanying symptoms.
In itself, OA is not a life threatening condition although it can affect considerably the quality of life. OA can be classified depending on the number of joints affected, the site which it affects and also the type. By type, one means whether it is inflammatory, generalised (affects many joints) or erosive (David & Lloyd, 1998). Osteoarthritis may also be divided into primary idiopathic or secondary. In primary OA there are no preceding injuries or trauma which could have caused it. The main cause is repetitive stress on the joint and cumulative changes to the joint surfaces. It is typically found in women over the age of forty five which repeatedly stress the same joints such as the knees and hips. Secondary OA, on the other hand, is caused by a previous condition, injury or disease. Injury to the joint, gout, rheumatoid arthritis and even obesity may eventually lead to the development of secondary OA (Koopman, 2000)
Osteoarthritis Affecting the Knee Joint
The knee is the most susceptible joint for development of osteoarthritis. As previously mentioned in the section discussing knee anatomy, the knee is formed by three combined compartments: the lateral tibiofemoral compartment, the medial tibiofemoral compartment and the patellofemoral compartment. As osteoarthritis very rarely affects the joint uniformly, degeneration may be occurring in any one of the different compartments. The medial tibiofemoral compartment of the knee takes on most of the body’s weight during ambulation and so is the most common site for degeneration to occur (Banwell & Gall, 1987). A variety of factors occurring within the joint lead to OA of the knee.

Loss of Cartilage and Development of Osteophytes
OA is a continuously active condition and targets the joint tissue as a whole. The articular cartilage of the joint deteriorates gradually leading to the wearing down of the joint surface. Here, remodelling of the bone takes place. When bone deteriorates in a particular region, new bone simultaneously forms in another region as if to compensate. This is why there is a change in shape at the joint affected by osteoarthritis. This regeneration of bone occurs in two different regions regarding the joint surface: at the margins of the articular cartilage as exophytic growths (marginal osteophytes) and in subjacent bone marrow.
Osteophytes are mainly made up of bone which merges with the cancellous and cortical tissue of the underlying bone and are lined by hyaline cartilage and fibrocartilage which continue with the proximal synovial lining of the affected joint. Marginal osteophytes consist of two growth patterns. One growth pattern involves the growth of a bony tuberosity into the joint space while the other involves a growth within the attachments of the capsule and ligaments to the joint margins. If left untreated, sclerosis of the untreated bone may develop i.e. the thickening of the subchondral bone which serves as the body’s way of compensating for the continuous wearing down of the articular surfaces. In advanced stages of OA, the surface of the osteophytes themselves can start to degenerate. Thus, osteoarthritis can be described as a gradual mechanism which the body uses to overcome the initial trauma at the joint. In its initial stage, although the structure of the joint is somewhat altered, it is symptom free. It is when this regeneration process cannot keep up with the wearing down of the cartilage that tissue damage, and thus symptomatic osteoarthritis, occurs (Koopman, 2000).

Lack of Lubrication between the Joint Surfaces
As long as lubrication is present within the joint, the cartilage found at the articular surfaces is resilient to abrasion. Thus, there is around 80 percent of water within the surface of the articular cartilage so that it is constantly kept moist. This water creates an appropriate osmotic potential which causes fluid to flow back into the cartilage when pressure is low. Pores within the cartilage also create a way to control the fluid as they prevent it from leaving the cartilage. Apart from the presence of this water, there is also synovial fluid which aids in lubrication. The latter is a viscous fluid composed of large molecules making it an extremely ideal shock absorber. Irregularity in the opposing joint surfaces, i.e. the femur and the tibia, and of intra-articular surfaces such as the menisci enhances this lubricating mechanism even further. This is because a certain degree of movement of one component surface in an asymmetrical joint causes lubricating fluid to be sucked between the two adjacent surfaces. This is according to a concept found out in 1932 by MacConaill i.e. the concept of “congruity versus incongruity” (Cailliet, 1991, p. 191).
Keeping this concept in mind, fluid does not flow out at the point at which articular surfaces meet under direct pressure on the cartilage. However, it does ooze into the defected joint and when the joint surfaces slide past each other, it spreads out. Under the pressure of the irregular joint surfaces, the cartilage closes of the joint space so that the amount of appropriate lubrication within the joint is lost. Within the joints of the body, there exists boundary lubrication which in simple terms is layers of lubricating molecules that adhere to opposing joint surfaces and slide over each other. Boundary lubrication provides just enough fluid to maintain a low friction coefficient during low weight-bearing conditions. However, the knee takes on a lot of weight and in addition to its already lack of lubrication due to the abnormalities occurring within the joint shape, it is not enough to prevent friction between the bone surfaces.
The hyaline cartilage is very compliant under increasing pressure making it extremely susceptible to wear. Lack of lubrication within the joint and the continuous scraping of the articular surfaces together result in fatigue of the cartilage bringing about chemical alterations to it. These chemical alterations result in its deformation and tension is built up in its periphery (and thus in the periphery of the joint). The size of the pores mentioned earlier changes and so the osmotic pressure changes as well. The remaining fluid along with the ground substance flows out, however a net exchange does not occur and under pressure the fluid does not return (Cailliet, 1991).
Alteration of Bone Matrix
Apart from the pore size, the matrix within is also altered chemically via the action of lysosomal lytic enzymes. The cartilage matrix is composed of chondrocytes, collagenous and elastic fibres. Collagen is broken down gradually so that there is a loss of matrix composition and surface continuousness. This process most commonly occurs in central regions of the hyaline cartilage where patches of fibrillation occur forming small pits. The process of fibrillation may result in small bits of loose cartilage to form and cause secondary synovitis. Four layers of cartilage are present: superficial, middle, deep and calcified layer which is directly attached to the underlying bone. Metabolic changes vary between the layers so that the superficial cartilage layer is more prone to damage. Since nerve endings are not present within cartilage and subchondral bone lacks pain receptors, this stage of OA is usually asymptomatic. This sort of fibrillation is progressive and is unlike that of ageing where OA is not progressive
When the articular cartilage is worn down, the underlying bone hardens due to increased metabolic activity. Osteophytes and chondrophytes form and accumulate at the joint margins and synovial hyperplasia occurs. As an attempt to repair the cartilage matrix, there is an increase in chondrocyte activity and a combination of fibro cartilage and hyaline cartilage form. This increase in cartilage formation causes osteoblastic activity to increase and remodelling of the bone end occurs. Subchondral cysts may form in the cancellous bone and marginal osteophytes form to attempt to provide joint stability. As the bones start to rub against each other degeneration progresses and sub-articular bone is continuously exposed. Hypertrophy of the capsule, ligaments and tendons as well as deterioration of the synovial membrane accompanies this process (David & Lloyd, 1998).

Direct Injury to Knee
Trauma may be a cause of osteoarthritis. When a lesion in the knee is deep enough, it disrupts the underlying bone plate which then undergoes characteristic changes. The wound fills with blood coming from the end plate blood vessels and almost instantaneously coagulates into a fibrous clot. Some of the blood cells caught up in the mesh work turn into fibroblasts up to ten days after the injury. Combined with chondrification, fibrocartilaginous tissue is formed. This serves as a way for the body to cover up the defect which then remains there for years. The change in the joint surface may then lead to the development of osteoarthritis. Thus, trauma may serve as a direct push to the usually gradual process involved in this condition.
Overall, during the process, increased load due to muscle contraction and weight make the areas of contact within the joint larger and remodelling occurs to form a more seemingly functional joint. A smaller load will get a larger response from the joint. In the end, collagen fibres either break down or turn into a part of the cell matrix leading to increased irregularity in the bone surfaces. Not only does this wearing down of bone and cartilage affect the joint but it also results in loss, failure or deficiency of the ligaments and muscles of the knee and damage to the menisci (Cailliet, 1991).

Comparison between a healthy knee and a knee affected by OA

Risk Factors and Causes
Several risk factors such as obesity, age, gender, metabolic and genetic influences are related to the development of osteoarthritis in the knee.

* Age and Gender
It is common knowledge that osteoarthritis is most common in the older generation although as discussed above, it can develop secondary to trauma or other conditions at any age. It is also more common in women than in men (Felson, 2006). Age and gender therefore lead to primary osteoarthritis. (Felson, David T., 2006. Osteoarthritis of the Knee. The New England Journal of Medicine, 354(8), 841-848. Retrieved 21st December, 2014 from http://www.udel.edu/PT/PT%20Clinical%20Services/journalclub/sojc/05_06/mar06/felson.pdf.).

* Metabolic factors
Metabolic factors are linked to secondary osteoarthritis. Patients with metabolic diseases such as hemochromatosis are susceptible to developing this condition. Some may say that diabetes mellitus, which is the most common metabolic disease, is associated with the development of secondary osteoarthritis however solid proof remains unavailable. The research of the correlation between these two is complex since the risk factors of type II diabetes mellitus and OA are very similar especially when it comes to obesity (Koopman, 2000)

* Genetic Factors
Genetic factors also play a major part in knee OA. If there are members of a person’s family who developed this condition then it may be likely that the person may develop it as well. The nature of the genetic effect may be structural (collagen formation), changes in the metabolism of cartilage or bone, or even a genetic influence which triggers a condition e.g. obesity and which then leads to osteoarthritis (Cicuttini & Spector, 1996). Although not all of the specific genes are known, it is a fact that more than one gene is involved in the process. A gene which may be linked to early knee osteoarthritis is vitamin D receptor gene polymorphism research is still being carried out. Studies on twins have shown that identical twins are more likely to simultaneously develop osteoarthritis than fraternal twins, proving that genetic influence on the knee is present. Needless to say, genetic factors lead to primary osteoarthritis as it appears at the knee joint seemingly without a cause (Koopman, 2000).

* Obesity
Obesity is a main contributory factor to the development and progress of osteoarthritis of the knee. Risk in obese people is even further increased when these people have other contributing factors such as being a female over the age of fifty five. Joint damage can occur due to both metabolic and mechanical factors. Obesity brings about an increased level of metabolic syndrome components of the blood such as lipids, adipokines (especially leptin) and other metabolic mediators which aid the disease progress. Mechanical factors however are the main factors responsible for knee osteoarthritis. Obesity imposes a large mechanical burden on the knee joint and as a result patients develop a greater absolute knee adduction moment and compensate for this in their gait by walking slowly. The articular cartilage cannot always keep up with this increased absolute knee adduction and so the progress of osteoarthritis is accelerated (Anandacoomarasamy, King & March, 2013).

* Daily Life Activities and Mechanical Factors
Certain activities which inflict a mechanical strain on specific joints can act as leading factors of OA. In the case of the knee, individuals who have jobs involving heavy labour or frequent squatting are likely to develop OA at this joint at some point of their life. Squatting repeatedly may eventually lead to tibiofemoral knee OA in later years. According to a study carried out by ‘The Caspian Journal of Internal Medicine’, individuals with occupations that require over two hours a day of kneeling and squatting showed a two-fold increase of risk of developing knee OA compared to those with less strenuous jobs. (Heidari, 2011).

* Fractures of the Knee and Other Conditions:
Injuries to the knee may cause the later development of osteoarthritis in that area. Examples of such injuries include: * Fractures of the Distal End of the Femur:
The distal end of the femur is made up of two round condyles surrounded with cartilage. The muscles and ligaments related to the joint must be considered as they affect the resultant alignment and fracture fragments especially the collateral ligaments and the gastrocnemius muscle which pulls the femur backwards the blood vessels and nerves of the popliteal fossa. Hemarthrosis of the knee joint usually occurs. Irregular realignment of the joint surfaces as well as muscle atrophy and intraarticular adhesions can all lead to secondary osteoarthritis.
Fractures of the distal femur may be of different types. For instance, the fracture may be a supracondylar fracture. This is usually the result of direct violence or abrupt twisting of the knee (torsion stress). Usually, the fractures are displaced due to the gastrocnemius pulling the femur back into the popliteal fossa along with the hamstrings and quadriceps shortening the femur (Cailliet, 1991).

Different supracondylar f fractures

Another type of femoral fracture is an intercondylar fracture which is further classified as a ‘Y’ or ‘T’ type judging by the shape of the fracture. It is more serious than a supracondylar fracture as the damage done to the soft tissue may be widespread. It causes the knee to be extremely unstable due to a prominent reduction in length of the femur (Cailliet, 1991).

A direct blow to the knee due to a large varus or valgus force will cause a condylar fracture. Although the fracture line can occur in different planes, it is most commonly present in a straight line in the sagittal plane. The ligaments on the affected side usually help to stop displacement however, the ligaments on the unaffected side as well as the cruciate ligaments are impaired (Cailliet, 1991).

* Fractures of the Proximal End of the Tibia
The proximal end of the tibia consists of two condyles separated by weak bone making the tibial plateau more susceptible to fractures. The cause is usually direct violence in line with the tibia or even a lateral blow which causes the knee to abruptly adduct or abduct. The lateral condyle is more commonly fractures than the medial and it is associated with injury to the cruciate ligaments and medial ligamentous structures. It may be crumpled, backed into the fracture site or forced medially into the knee joint. A strong lateral force onto the tibia may result in the fracturing of the medial condyle, crumpling of the medial meniscus and tearing of the lateral collateral ligaments.
Direct violence can result in a straight fracture of the tibial plateau in a ‘T’ or ‘Y’ formation. It is possible that the central fracture protrudes into the site of injury causing varied deformities as well as blood effusion (Cailliet, 1991).

* Fractures of the Patella
Since the patella is exposed, it is in a vulnerable position and so is commonly fractured. When the knee is flexed, it is especially susceptible to injuries especially in car accidents. The cause may be a direct blow caused by an object or by falling directly on it. A fractured patella causes tenderness around the knee as well as bruising, inflammation and irregularity in the shape of the knee. Fragmentation may be palpated and further damage may be seen on X-ray (Cailliet, 1991).

Different Patellar Fractures

* Chondromalacia
Present research hypothesises that this condition is caused by repetitive localized trauma and remains dormant until a larger trauma occurs. Apart from repeated trauma, it may also be caused by a sustained load inflicted on the cartilage which reduces its elasticity as well applying excess pressure on the tissue. Abnormalities in the anatomy of the patella and condyles of the femur may lead to chondromalacia and eventually osteoarthritis. It is usually divided into four stages: inflammation and softening of cartilage, division of the soft cartilage, distortion of the surface- ‘fasciculation’ and finally osteoarthritis. The latter occurs when the fissures reach the underlying bone accompanied by a ‘vascular response’ (Cailliet, 1991).

Symptoms (rheumatoligical physiotherapy, carol david, jill Lloyd pgs 85-87)
There are several symptoms which a person undergoing OA of the knee may feel over a period of time.

1. Pain
The first feelings of pain usually start when one carries weight-bearing activities such as going up the stairs. Patients usually describe it as increasing its intensity at night or while resting. This is because while the leg (and knee) are in a resting position there is an increased pressure on the underlying subchondral bone. As osteoarthritis may affect several structures within the joint, the source of pain is not always the same. Some sources may be: * The soft tissue surrounding the joint (strains in the capsule or surrounding ligaments) * Muscle weakness (hamstrings and quadriceps muscles and gastrocnemius) * The synovium (may be stretched out or inflamed) * The periosteum of the tibia or femur due to an increase of pressure within the bone * The knee joint itself as it is unable to cope with the usual movements which it carries out (David & Lloyd, 1998).

2. Stiffness
Due to the degeneration of the articular surfaces composing the joint and secondary inflammation in the synovium, there is much less soft tissue compliance than in a healthy joint. This results in the patient feeling a lot of stiffness in his/her affected knee. The osteophytes and other subchondral changes which occur to attempt to heal the joint also cause stiffness and diminished joint mobility (David & Lloyd, 1998).

Presence of osteophytes and loss of cartilage cause stiffness of knee.

3. Inflammation and Effusion
Although not always present, if the osteoarthritis is well developed or if the patient has continues to put a strain on the affected knee, it will visibly swell. The inflammation may lead to other related symptoms such as the area feeling hot, erythema (redness), discomfort, pain, tenderness on touch and effusion of the joint. Although the effusion may be intermittent, it is common for knee effusion to become chronic (David & Lloyd, 1998).

4. Loss of Range of Movement

The combination of all the above mentioned symptoms will naturally lead to a decrease in range of motion of the knee. Thus, the patient will find it hard or will not be able to carry out all his/her activities of daily life. This may affect the person psychologically since the person feels limited or less adequate than before. On proper instruction, this is reversible however of the progress of osteophyte deposition is too far on, the restricted range of movement of that joint may be permanent. The joint may develop a capsular pattern meaning that only certain ranges of movement are restricted. In the case of the knee, flexion 5contractures may occur where 75% of the time, the medial compartment is involved, in 25% of the time, the lateral compartment is involved and finally in 48% of the time the patello-femoral compartment is involved (David & Lloyd, 1998).

5. Muscle Inhibition and Atrophy
If an effusion is present it will restrict the surrounding muscles of the joint from contracting normally. If muscle inhibition becomes chronic, chronic pain may be felt as well as muscle atrophy and weakness may occur (David & Lloyd, 1998).

6. Joint Instability
Due to weakening of the surrounding muscles and possibly ligaments, especially if this weakness is not uniform throughout the joint, muscle imbalance may occur. Sporadic episodes of pain may cause the joint to give away. Along with these changes stretching of surrounding soft tissue due to swelling and osteophytes will change the alignment of the joint resulting in instability and even eventually subluxation of the knee (David & Lloyd, 1998).

7. Deformities
As mentioned previously, osteophytes are produced to make up for the degradation and instability of the bone by increasing the joint surface area. This may result in visible deformities in the knee region as the osteophytes may not be distributed evenly along the medial and lateral joint margins. Changes in the joint biomechanics will occur and varus or valgus deformities may be observed. The OA is usually far in progress for such deformities to be seen (David & Lloyd, 1998).

8. Reduced Function
A combination of all or some of the above will indefinitely reduce the function and performance of the knee. Climbing up the stairs, walking a distance, getting out of chairs etc. will all become difficult activities to perform. After treatment of the knee, the patient should be able to return to their activities of daily life by either adapting their activities to their condition, managing their symptoms and re-strengthening their muscles (David & Lloyd, 1998).

Diagnosis
In order to determine whether a patient does in fact have OA of the knee certain assessments and tests must be carried on the patient. Primarily, the patient’s medical history is taken and examined. Next, a physical examination is carried out on the patient where the medical professional looks for any of the symptoms mentioned in the previous section. If the symptoms of OA are present then imaging studies such as X-rays and magnetic resonance imaging (MRI) are carried out. Although there are no specific laboratory tests for OA, certain lab tests can be used to rule out other pathologies such as hypothyroidism, gout and septic arthritis. * Medical History
A series of questions regarding the patient’s background are asked in order to aid with the assessment. Some questions commonly asked are: * What job do you currently have and what jobs have you had in the past? * Do you exercise or play any sport? * Have you ever injured your knee in the past? * When did the symptoms start and have they increased in severity over time? * How intense is the pain on a scale of 1 to 10, 10 being the most painful? * Is the amount of pain constant throughout the day or is it different at different times? * How long does the pain last? * Does the pain wake you up at night? * When bending and straightening the knee do you feel grating within the joint? * Have any family members suffered from osteoarthritis or any other problem related to joints? * Are you currently taking any form of medication? * What medication have you taken in the past?

* Physical Examination
The next step after noting the patient’s medical history is to carry out a physical examination. Symptoms mentioned previously including swelling and redness at the knee joint stiffness, pain on touch, visible deformities of the bone and loss of ability to straighten and bend the knee are sought after and noted down if present (My Doctor Online, n.d.). http://mydoctor.kaiserpermanente.org/ncal/mdo/presentation/conditions/condition_viewall_page.jsp?condition=Condition_Knee_Osteoarthritis.xml& * Radiology
An X-ray of the knee is usually taken to confirm the presence of osteoarthritis and to determine its severity. A grading system of OA severity when observed radiologically was established in 1957 by Kellegren and Lawrence. The grades span from 0 to 4: 0- No evidence of OA visible on X-ray 1- Slim chance of it being present 2- Can be identified but severity is at minimum 3- Moderate severity 4- Osteoarthritis is well developed and severe, changes clearly visible
Three main characteristic changes are used to confirm the presence of OA and its severity. These are the presence of osteophytes (which show up as extra bone around knee), the narrowing of the joint space between the femur and the tibia and also sclerosis of the subchondral bone. The alignment of the joint and the presence of cysts in the subchondral bone should also be sought for. Occasionally, one can observe the thickening of the capsule and effusion within the joint. However, the grading of severity of OA based solely on the X-ray is not accurate as there is often a difference between what is shown on the X-ray, the symptoms the patient is describing and the clinical features observed (David & Lloyd, 1998).

X ray image showing the three main characteristics of OA

For a more detailed image of the soft tissue a magnetic resonance imaging (MRI) scan is usually taken as the wearing down of cartilage is seen more clearly (David & Lloyd, 1998).

MRI scan of knee in sagittal plane

* Laboratory Investigations
As mentioned above, these are carried out to eliminate the possibility of the symptoms being due to an alternate pathology. Blood tests are an ideal way to exclude numerous conditions such as gout and rheumatoid arthritis. A synovial fluid test may also be carried out by inserting a needle and extracting synovial fluid from the joint. Typically, synovial fluid is viscous, clear and the colour of straw with a low cell count. Any alterations in the content or appearance indicates that the joint is not normal. Fragments of cartilage present in the fluid may be an indicator of osteoarthritis (David & Lloyd, 1998).

Blood samples from blood tests

Synovial fluid test

* Other Investigations * Arthroscopy can be used to detect small, localized changes within the knee joint * Computerised Tomography (CT) scan (has the disadvantage that it cannot identify hyaline cartilage) * Ultrasound of the knee as it can show effusions * Thermography can detect differences in temperature and measure the amount of blood flowing superficially when there is a large amount of soft tissue involvement (David & Lloyd, 1998).

CT scan of the knee in the sagittal plane

Ultrasound of the knee joint

Thermography of knees

Treatment:
The main aims of treating an osteoarthritic knee are to relieve the patient of pain and to increase the range of motion of the knee. It must be said that OA cannot be cured however the process can be slowed down effectively by following the advice given by medical professionals. Usually, the patient will firstly contact the general practitioner (GP) after noting any symptoms in their knee. The advice given by the GP depends on the individual and also on the severity of the condition. Advice can be as simple as weight loss, exercise and applying heat or cold to the joint. However, if the OA is severe the GP may prescribe certain medication, refer them to other health professionals or even recommend surgery (David & Lloyd, 1998).

* Exercise Therapy
Following an effective exercise regime along with being educated about why these exercises are being carried out make up an important part in the overall rehabilitation process. Exercises to treat knee OA should be mainly carried out in a joint-loading position to maintain the original form of the articular cartilage and to regain muscle strength, especially in the extensor muscle groups. Patients should be cautioned that at first inflammation of the joint may be induced however, in the long run their activities of daily living will be improved. The main aims of exercise therapy are to: * Increase and Maintain Range of Movement- may be done through free active exercises, active assisted exercise or hydrotherapy. Stiffness in joints can be decreased by incorporating passive stretches and active contraction of the antagonist muscle group in the treatment programme. * Increase Muscle Power- may be done through free active exercises at a grade 3 on the oxford scale (against gravity), concentrically and eccentrically, hydrotherapy and by using weights or a theraband (grades 4 to 5 on the oxford scale) * Increase Endurance- may be done by doing exercises in a weight-bearing position while carrying out slow repetitions if possible. * Increase Aerobic Capacity- It is essential to include a warm up and a cool down. Exercises can be carried out in a form of progression to increase heart and respiratory rate. * Increased Activities of Daily Living Capacity- Tasks that are usually carried out by the individual should be practiced under the supervision and guidance of a health professional.

Exercise also aids weight loss and so indirectly reduces pressure on the affected knee joint as well as pain. Not only can exercise be beneficial physically but it can also help the patient psychologically. Studies have indicated that after carrying out aerobic activities for three months there is a reduction in levels of anxiety and depression in individuals. The patient should always be advised to stop the work out if they feel discomfort or pain during the exercises. Exercises should also be stopped if after the workout there is abnormal joint swelling, a notable feeling of fatigue, muscle soreness which persists or pain that remains for more than two hours after the session. If any of these occur the physiotherapist should recommend exercises of a lower intensity (David & Lloyd, 1998).

* Physiotherapy Management
It is a wise choice to go to a physiotherapist to treat an osteoarthritic knee as physiotherapists aim to aid individuals to regain function and mobility of that knee. In the long term, the patient should be able to manage their condition independently while getting the maximum function out of it. The physiotherapist needs to observe and conduct a few assessments in order to plan an adequate regime for the patient: * History of Patient- The symptoms that the patient feels and previous physiotherapy or other therapy sessions which the patient has undergone should be noted. It is also important to learn what relieves or increases pain and at what time of the day or night these fluctuations occur. * Palpation- On palpating the knee area, the presence of an effusion, active synovitis or an increase in temperature should be noted. * Joint Stability and Proprioception- An unstable joint may accelerate its degeneration since there is a lack of afferent information going back to the CNS. Thus, proprioception is tested primarily in a non-weight bearing position and then progressing to a weight bearing position with no visual clues. * Range of Movement- Both active and passive ranges of movements affecting the joint should be noted along with the reason for lack of completion of the full range. At the knee, a slight flexion contracture will result in a certain degree of handicap as there is compensatory hip flexion and an increased degree of lumbar lordosis to facilitate knee extension. These limited movements should be noted and corrected accordingly. * Muscle Power- the Oxford scale is commonly use although it is not completely reliable. Static and dynamic as well as eccentric and concentric tests may also be carried out using isokinetic machines. * Muscle Function- Involves static and dynamic tests and should be relevant to the form of life style the individual leads. * Gait Analysis- This can be assessed by timing a patient’s walk for a specific distance. When analysing gait, insoles and footwear should be considered. Transfers with or without aids, the quality of movement and postural awareness should be assessed accordingly. * Exercise Tolerance- Knee OA patients in chronic pain commonly have a reduced aerobic capacity, restricted mobility and are less capable of carrying out activities of daily living. Due to this, they are less confident in their ability to get fit and push themselves to a certain limit. * Psychological Factors- A full understanding of what the patient is going through must be kept in mind at all times. The pain and disability which the condition brings with it may cause symptoms of depression. Thus, empathy and open discussion should be present during treatment.

At the end of the assessment, the physiotherapist can formulate aims of treatment and discuss these with the patient. Self-management of the condition should be emphasised and a clear description and prognosis of the condition should be given to the patient to help them understand what they are going to be dealing with. Encouragement and simple advice to improve their daily life should be given (David & Lloyd, 1998).

* Medical Management:
Apart from non-pharmacological methods, pharmaceuticals may also be used to relieve cardinal symptoms of osteoarthritis. Often, a simple analgesia is prescribed such as paracetomol or tramadol however, when symptoms are more serious other medication may be advised:

* Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)
NSAIDs are a wide range of drugs which act to decrease the pain, stiffness, distension and warmth brought about by inflammation. Common NSAIDs are aspirin, Ibuprofen and Diclofenac. However the prescription of NSAIDs for OA is debatable since inflammation is not a prominent symptom. Certain kinds of NSAIDs may even speed up joint deterioration as they affect cartilage metabolism. If analgesics do not suffice and NSAIDs must be used, it is better to use topical NSAIDs for knee OA such as ibuprofen cream or piroxicam gel. However it is advisable that they should not be used for long term as they could cause side effects. For instance, Capsaican cream has shown to decrease pain in the osteoarthritic knee by 30 percent, however it is common for patients to feel burning in that area and may even conduct skin allergies.

Mild side effects which may occur in certain users are those affecting the gastrointestinal tract. In the upper tract NSAIDs may induce erosion, gastric or duodenal ulceration and even dyspepsia. Patients with peptic ulcers should take extra caution as bleeding or perforation of the ulcer may occur. Other side effects caused by different NSAIDS may be hepatic, renal, haematological and hypersensitivity problems, asthma, headaches and dizziness (David & Lloyd, 1998).

* Hyaluronic Acid Injections:
Hyaluronan is a substance found naturally in the synovial fluid of the joint so the aim of this injection is to replenish the supply in the joint. However, whether it actually works or not is in strong debate. Some say that it has no effect whatsoever on the pain or other symptoms while others argues that it does help to a certain extent (Felson, 2006).

* Glucosamine and Chondroitin Sulfate
These two substances are commonly used to treat osteoarthritis despite the fact that the way that they work exactly is uncertain. Some studies reported less side effects and greater relief of pain regarding these two substances than placebo pills and NSAIDs (Felson, 2006). Glucosamine sulfate is found naturally in the body more specifically in the glycosaminoglycans of the extracellular matrix where it acts as a building block (David & Lloyd, 1998).

* Intraarticular Cortocosteroid Injections
When all other therapy methods fail to work, these are given to the patient. The long term effects of these injections are unknown and so it is advised that these injections are not given to the joint more frequently than every three months. The known effects are only short term so that pain and inflammation are relieved for just a short period of time. Thus, it is useless for patients suffering from chronic osteoarthritis (David & Lloyd, 1998). Mild to moderate pain at the site of injection is common. (Felson, 2006)

* Surgical Management
If the joint is too damaged to repair or if the pain cannot be managed by medication or other techniques, surgery should be considered. Unlike medical management, which treats the symptoms of OA, surgical management aims to repair or salvage the joint. There are different types of surgeries and the kind best suited for the patient depends on the area and also severity of the knee joint. Four surgeries involving the knee are arthroscopy, osteotomy, arthroplasty and arthrodesis (David & Lloyd, 1998).

* Arthroscopy
This is a simple procedure which can both serve as a means of diagnosis as well as a means of treatment. In itself, an arthroscopy involves inserting a fibre optic arthroscope into the knee joint via a small incision and visually inspecting the joint. Surgeons can directly examine joint surfaces enabling them to note the extent of joint damage present. If surgery is required, probes, forceps and other surgical devices can be delivered down the arthroscope. If there is effusion at the knee joint, an arthroscopic washout out with saline could aid to dislodge and remove any loose particles within the joint. If the inflammation subsides, pain decreases considerably and the range of motion of the knee joint increases resulting in an improved quality of life. An arthroscopy puts off the need for more intense surgeries, providing more time to plan the surgical management of the patient (David & Lloyd, 1998).

* Osteotomy
Osteotomies are performed to correct structural problems which affect the biomechanics of the joint such as genu varus deformity (David & Lloyd, 1998). It involves cutting and reshaping of the bones involved with the joint. In the case of the knee, there is cutting and reshaping of the tibia or femur so that pressure is relieved from the knee joint. As it involves shifting of weight, this surgery is performed when OA is still in its early phase to relieve the pain and increase the function of the knee. This procedure involves the removal of a wedge of the tibia or femur so that when it is closed, the leg straightens. Thus, there is more room between the bones on the arthritic side so weight can be distributed more evenly. However, since this only relieves pain it does not entirely solve the problem of osteoarthritis so that eventually the need for a more serious surgery may be needed (American Academy of Orthopaedic Surgeons, 2011)

* Arthrodesis
This type of surgery is uncommon and involves the surgical fusion of the knee, in the case of knee OA, in its position of optimum function. Its main aim is to restore the stability of the knee joint and also to relieve the pain felt in this region. Such a procedure is performed when the joint is exceedingly damaged. Another reason is that it could be the only alternative after a failed joint replacement. As a result of this surgery there is loss in range of movement and mobility and so function is quite limited. However it is possible for the patient to learn compensatory movements (David & Lloyd, 1998).

* Arthroplasty
An arthroplasty is a procedure where the joint is remodelled to decrease pain, increase joint range and thus function of the knee. There are two main types of arthroplasty these being excision and replacement.
An excision arthroplasty are where there is excision of one or even both components of the joints. On the other hand, a replacement atrophy is the replacement or covering of the joint with synthetic material (in this case a metal or ceramic ball and socket) after its excision or remodelling. In this case, the procedure is commonly known as a total knee replacement. Knee arthroplasties are usually highly successful as long as the patient is compliant and understands the importance of post-operative treatment and rehabilitation (David & Lloyd, 1998).
Before undergoing a knee arthroplasty, the patient’s age, weight, ADLs and present medical conditions must be considered. For those in the younger generation a tibial osteotomy may be a better option. Regarding weight, if a patient is obese the life span of the knee replacement is considerably reduced (Cailliet, 1991).

Surgical treatment is only resorted to when the OA has become too severe to handle. However, if the OA is not too far gone, the previously mentioned techniques can be performed in conjunction with a few other pain relieving methods: * Mobility Aids- It is important to have periods of partial weight-bearing when the joint is inflamed as long periods of immobility may induce stiffness and pain. However one must not spend too much time using aids and periods of rest should be established in between. * Ice Therapy- If an effusion is present, ice may be the best option as it temporarily reduces the pain and swelling. * Taping the patella medially- The patient himself can apply the tape which aids the the mechanism of the quadriceps. The tape works by relieving some of the compression and pain which this brings with it caused by the degeneration of the lateral facet of the patella femoral joint. . This should be accompanied by concurrent strengthening exercises especially the strengthening of the vastus medialis obliquus (David & Lloyd, 1998).