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knee care at computer work

Posted by sailjamehra on May 22, 2009




There are many types of arthritis (rheumatoid, degenerative, post-traumatic, auto-immune induced, etc). The most common form is osteoarthritis. It is also known as degenerative joint disease (DJD). While the exact cause is unknown, there are known to be several possible causes including: injury, age, congenital predisposition and obesity.



‘Osteoarthritis is idiopathic, slowly progressive disease of the synovial joints occurring in life and characterized pathologically by focal degeneration of articular cartilage, bone thickening, osteophytes formation and joint deformity.’

The word arthritis means inflammation (swelling) of a joint. Osteoarthritis, also known as “wear and tear” arthritis is the most common type of arthritis. It is estimated that osteoarthritis affects nearly 55% of Indians over the age of 65.Danielsson in 1964 first reported a 40%incidence of osteoarthritis above the age of 50. ‘Osteo’ means ‘bone’ and ‘arthritis’ means ‘joint damage’. The joint affected are spine, hip ,hands, knee. Osteoarthritis places a tremendous physical and economic burden on the society because it is the most prevalent musculoskeletal disorder.  The knee is one of the most common joints affected by this disease.

A joint is where two bones meet. Most of our joints are designed to allow the bones to move in certain directions. The knee is the largest joint in the body, and also one of the most complicated because it has many important jobs to do. It must be strong enough to take our weight and must lock into position so we can stand upright. But it has to act as a hinge, too, so we can walk. It must also withstand extreme stresses, twists and turns, such as when we run or play sports. Osteoarthritis of the knee affects different people in different ways. Some people have a problem with only one knee, others with both knees As a result, it is not very helpful to compare the experience of one person with another, and we cannot predict the eventual outcome for any one individual with osteoarthritis.

Most types of treatment for osteoarthritis of the knee work best when started early, before there is a lot of “wear and tear” in the knee. Doctors and physiotherapists who deal with people who have osteoarthritis can help outline a treatment protocol. Every osteoarthritic knee is different, and there should be a team approach to treatment. Physiotherapy is an important part of the treatment program for people with osteoarthritis of the knee. A knowledgeable physiotherapist will be able to provide more information about each of these types of treatments. While it may not be necessary to attend regular physiotherapy sessions, it may be helpful to consult a physiotherapist for an appropriate strengthening program that can be done at home. Additionally, a physiotherapist can help educate about proper exercise techniques and appropriate activities of the knee joint.





It is a hinge type of a synovial joint. It is not a typical hinge variety because the transverse axis around which the movement takes place is not static but moves forward during extension and backwards during flexion. In additional to these movements there are some rotational movements also possible in the joint.


There is a steady rise in the overall prevalence from the age of 30 such that by 65,80% of people show radiographic evidence of OA though only 25-30% have associated symptoms. Knee OA is prevalent in all racial groups but hip, hand and generalized OA are only prevalent in Caucasians. OA is more prevalent and more commonly associated with symptoms in women ,except at the hip where both genders are equally affected. Recognised occupational risks for OA include farming (OA hip),mining(OA knee) and professional football(OA knee).












The knee joint is the largest joint in the body and the most complex .

BONES: The knee joint is made up of four bones, which are connected by muscles, ligaments, and tendons. The femur is the large bone in the thigh. The tibia is the large shin bone. The fibula is the smaller shin bone, located next to the tibia. The patella, otherwise known as the knee cap, is the small bone in the front of the knee. It slides up and down in a groove in the femur (the femoral groove) as the knee bends and straightens. The knee joint is formed by the condyles of the tibia and the condyles of the femur and the patella.


The joint is surrounded by a membrane which produces small amount of thick fluid called synovial fluid which helps to nourish the cartilage and keeps it slippery.


The fibrous capsule is very thin, fibrous sac covering the joint It is deficient anteriorly where it is replaced by the quadriceps femoris patella and ligamentum patella. Attachments: proximally: to the upper margins of the medial and lateral femoral condyles.Distally: to the margins of the tibial condyles. Medially: to the medial margins of the medial condylar surfaces. Laterally: to the lateral margins of the alcondyles.    





There is another type of cartilage in the knee called articular cartilage. This cartilage is a smooth shiny material that covers the bones in the knee joint. There is articular cartilage anywhere that two bony surfaces come into contact with each other. In the knee, articular cartilage covers the ends of the femur, the femoral groove, the top of the tibia and the underside of the patella. Articular cartilage allows the knee bones to move easily as the knee bends and straightens.


Ligaments are like strong ropes that help connect bones and provide stability to joints. In the knee, there are four main ligaments.

On the inner (medial) aspect of the knee is the medial collateral ligament (MCL)Attachements: to the above to medial condyles of the femur and below to the medial margins and adjoining medal surfaces of tibia.

The outer (lateral) aspect of the knee is the lateral collateral ligament (LCL).Attachements: It is a rounded cord like structure.  attached above to the lateral condyle of the femur and below to the head of the fibula.

Transverse Ligament: it connects the anterior end of the medial and lateral semilunar cartilage.

Coronary Ligament: it consists of short ligamentous fibres which serve to connect the peripheral convex margins of the semilunar cartilages with the peripheral margins of the tibia.

Arcuate ligament: it is attached to the posterior aspect of the femur above the lateral femoral condyle and fibres are directed downwards and medially to merge with the capsule.


The other two main ligaments are found in the center of the knee. These paired ligaments are called the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). They are very strong bands which maintain the stability of the knee joint. Anterior cruciate ligament:it is attached above to the anterior part of the intercondylar area of tibia between the anterior ends of the semilunar cartilages and above to the posterior part of the medial surface of the lateral femoral condyles. Posterior Cruciate ligament:it is attached below  to the posterior part of the intercondylar area of tibia and above to the anterior part of the lateral surface of the medial condyles.




 Two semilunar cartilages called menisci sit between the femur and the tibia. They are fibrocartilagenous discs which are shaped in the form of cresents. These structures act as “cushions” or “shock absorbers”. They also help provide stability to the knee. There is a medial meniscus and a lateral meniscus. When either meniscus is damaged it is often referred to as a “torn cartilage”.

Medial menisci: it is Cshaped and has 2 ends.the anterior horn is attached to the intercondylar area of the tibia and the posterior horn is attached to the posterior part of the intercondylar part of the tibia between the attachment of the lateral semilunar cartilage and posterior cruciate ligament.

Lateral menisci:it has 2 horns and the anterior horn is attached to the intercondylar area of tibia between the ACL and interondylar tubercle and the posterior horn is attached to the intercondylar area of the tibia. The strong quadriceps muscles on the front of the thigh attach to the top of the patella via the quadriceps tendon. This tendon covers the patella and continues down to form the “rope-like” patellar tendon. The patellar tendon in turn, attaches to the front of the tibia. The hamstring muscles on the back of the thigh attach to the tibia at the back of the knee. The quadriceps muscles are the main muscles that straighten the knee. The hamstring muscles are the main muscles that bend the knee.             

TENDONS: They connect the muscles to the bones. The strong quadriceps muscles on the front of the thigh attach to the top of the patella via the quadriceps tendon. Theis tendon covers the patella and continues down to form the rope like patellar tendon. this tendon in turn attaches to the tibia.



Finally, a bursa is a small fluid filled sac that decreases the friction between two tissues. Bursae also protect bony structures. There are many different bursae around the knee but the one that is most commonly injured is the bursa in front of the patella, the prepatellar bursa. Normally, a bursa has very little fluid in it but if it becomes irritated it can fill with fluid and become very large.

Anteriorly: suprapatellar bursa, prepatellar bursa, superficial  infrapatellar bursa ,deep infra patellar bursa.

 Laterally:  bursa between the lateral cruciate ligament and the popliteal tendon, popliteal bursa between the popliteal and the lateral condyle of the femur.

Medially: tibial intercondylar bursa, between the MCL and semimembraneous tendon

 Posterior: between lateral head of the gastroneimius and capsule., semimembraneous.                             




Seven muscles flex the knee.  The knee flexors are the semi membranosus, semi-tendinosus, biceps femoris, sartorius, gracilis, popliteus, and gastrocnemius muscles.

All of the knee flexors except for the short head of the biceps femoris and the popliteus are two – joint muscles.  As two joint muscles their ability to produce effective force can be influenced by the relative positions of the two joints over which they pass.  Four of the flexors (the popliteus, gracilis, semi-membranosus and semi tendinosus muscles) are considered to medially rotate the tibia on the fixed femur where as the biceps femoris is considered to be a lateral rotator of the tibia.

The semi-tendinosus, semi membranous and the bicep femoris muscles are known collectively as the hamstrings.  These muscles all orginate on the ischial tuberosity of the pelvis.  The semi membranosus, semi-tendinosus insert on the posteromedial and antero medial aspects of the tibia respectively.  The semi membranosus muscle has fibres that attach to the medial meniscus.  This attachment assist in knee flexion by facilitating  posterior motion of the medial meniscus during active knee flexion.


The Biceps femoris muscle has two heads, both of which insert on the lateral condyle of the tibia and the head of the fibula.  The biceps femoris tendon may be attached to iliotibial band and retinacular fibres of the lateral joint capsule.  The biceps femoris has a stabilizing role at the posterolateral aspect of the joint.  The short head of the biceps femoris does not cross the hip joint and therefore has a unique action at the knee joint.

The Gastrocnemius muscle arises from the posterior aspects of the medial and lateral condyles of the femur by two heads. It inserts into the calcaneus.  It is the only muscle at the knee that crosses the ankle and the knee.  The gastrocnemius becomes actively insufficient quite easily.  Rather than working to produce knee flexion the gastrocnemius appears to be effective in presenting knee joint hyper extension, it appears to be less a mobility muscle at the knee joint than a dynamic stabilizer.


The Sartorius muscle arises anteriorly from the anterior, superior, spine of the ilium and crosses the femur to insert into the anteromedial surface of the tibial shaft posterior to the tibial tuberosity although a flexor and medial rotator of the tibia, activity in the sartorius is more common with hip motion than the knee motion.

The Gracilis muscle arises from the inferior half of the symphysis pubis arch and inserts on the medial tibia by way of a common tendon with the sartorius and the semitendinosus muscle.  It is not only a hip joint  flexor and adductor but it can also flex the knee joint and produce slight medial rotation of the tibia.



The Popliteus is one joint knee flexor besides the short head of the biceps femoris is the relatively small popliteus muscle.  This muscle originates on the posterior aspect of the lateral femoral condyle and attaches on the medial aspect of the tibia. The popliteus muscle is a medial rotator of the tibia on the femur in an open kinematics chain, this muscle plays a very important role in initiating un-locking of the knee because it reverses the direction of the automatic rotation.





The four extensors of the knee are collectively known as the quadriceps femoris muscle. 


  1. Together the muscles of the quadriceps femoris extend the knee.






The ability of the patella to perform its function without restricting knee motion depends on its mobility.  The patella has the ability to slide on the femoral condyles while remaining seated between them.  In full knee extension, the patella sits on the anterior surface on the distal femur.  With knee flexion, the patella slides distally on the femoral condoles, seating itself between the femoral condyles .  In full flexion the patella sinks into the inter condylar notch.  The sagittal plane motion of the patella is called patellar flexion.  Knee extension reverses the sliding of the patella and brings it back to the patella surface of the femur.  This motion of the patella is refered to as patellar extension.



The triangularly shaped patella is distinguished by being the largest sesamoid bone in the body.  The articular surface of the patella is smaller than the femoral trochlear surface.  The posterior surface of the patella is covered by articular cartilage and divided by vertical ridge.  The patellar articulating surface of the femur is the inter condylar groove or femoral sulcus on the anterior aspects of the distal femur.



1) Semi tendinosus.


Root value         :   L4, L5,S1,S2

Action         :   Flexes and medially rotates the knee joint.




2) Semi membranous


Root value :   L4, L5,S1,S2

Action       :   Flexes and medially rotates the knee joint.



3) Biceps femoris


Root value  :  Long head – L5,S1, S2, S3

Short head – L5,S1,S2

Action  :    The long and short head of the bicep femoris flex and laterally rotate the knee joint.


4) Popliteus


Root value   : L5, S1

Action  : Flexion and internal rotation of the knee joint.




1) Rectus Femoris


Root Value : L2, L3, L4.

Action     :   The quadriceps extends the knee joints.



2) Vastus Lateralis


Root Value  : L2, L4


3) Vastus medialis & Vastus intermedius


Root Value   :  L2,L4

Action     :   It draws articular capsule proximally.




KINEMATICS:  Is the area of bio – mechanics that includes description of motion without regard for the forces reducing the motion. 


It is the area of bio – mechanics concerned with the forced producing motion or maintaining equilibrium.

  1. Consequently the femoral and tibial longitudinal axis normally forms and angle medially at the knee joint of 1850  – 1900 hence creating a physiological valgus angle at the knee. Although this might appear weight the lateral condyle more than the medial but this is not so.

 The mechanical axis of the lower extremity is the weight – bearing line from the center of the head of the femur to the center of the superior surface of the head of the talus.  This line normally passes through the center of the knee joint between the intercondylar tubercles.  Because the weight bearing lines follows the mechanical rather than anatomical axis, the weight bearing stresses on the knee joint in bilateral static stance are equally distributed between the medial  and lateral condoles.  If the medial tibiofemoral angle is greater than 1950 and abnormal condition called genu valgum ( knock knees ) exists.  This condition will increase the compressive forces on the lateral condyle while increasing the tensile stresses on the medial structures.  If the medial tibiofemoral angle is 1800 or less then resulting abnormality is called genuvarum ( bow leg ).  In this condition the compressor stresses on  the medial tibial condyle are increased whereas the tensile stresses are increased laterally.  In both cases constant overloading on the lateral or medial articular cartilage may result in damage to the cartilage.



The motion between the articular surfaces of a joint occurs between the tibial and femoral condyles and between the femoral condyles and the patella.

Tibiofemoral joint surface motion takes place in all three planes, simultaneously minimal in the transverse planes.

Patellofemoral joint takes place in two planes, simultaneously the frontal and transverse but is greater in the frontal plane.


In a normal knee this line is tangential to the surface of the tibia for each interval of motion from full extension to full flexion demonstrating that the femur is gliding  on the tibial condyles.  The surface motion of the joint is from 90 of flexion  to full extension in normal knees.


The surface motion of the patellofemoral joint in the frontal plane may also be described by means of instant center technique.  This joint also has a gliding motion.  From full extension to full flexion of the patella glides approximately 7 cm on the femoral condyles.  Both, the medial and lateral facets of the femur articulate with the patella from full extension to 90 of flexion.  Beyond 90 of flexion the patella rotates externally and only the medial femoral facets articulates with the patella, at full flexion the patella sinks into the inter condylar groove.


Static and dynamic analysis of the forces and moments acting on a joint.  Static is the study of the forces and moments acting on a body in equilibrium (body at rest or moving at a constant speed ).  Dynamic is the study of the moments and forces acting on a body in motion.  Kinetic analysis allows one to determine the magnitude of the moments and forces on a joint produced by body weight, muscle action, soft tissue resistance and externally applied load in any situation that produces excessive high moments and forces.


The three main coplanar forces acting on a free body and to the main moments acting about the joint under consideration to the minimum magnitude of the forces and moments.  Those forces are designated as vectors, if four characteristics are known that are magnitude, direction, sense line of  applicability and point of application.  The tibio femoral joint of the ground reaction force equal to body weight.  The tensile force through the patella tendon exerted by the  quadraceps muscles and the joint reactions force on the tibial  plateau .


The main forces considered in dynamic analysis are those produced by body weights muscles, soft tissues and externally applied loads.  Friction forces which are negligible in a normal joint are not considered.  In dynamic analysis two factors in addition to those in static analysis must be taken in to account.  That is the acceleration and the mass moment of inertia of the body part.  The steps for calculating the minimum magnitudes of the forces acting on a joint at a particular instance in time during a dynamic activity are as follows :



1)         The anatomic structures involved in the production of forces are identified.

2)         The angular acceleration of the moving body parts is determined.

3)         The mass moment of inertia of the moving body part is determined

4)         The torque (moment) acting about the joint is calculated.

5)         The magnitude of the main muscle forced accelerating the body part is calculated

6)         The magnitude of the joint reaction force at a particular instance of time is calculated by static analysis.



The magnitude of the muscle forces acting on a joint directly affects the magnitude of the joint reaction force.  In general the greater the muscle force is, the greater is the joint reaction force. When the knee bends 90 this force is reached 2.5 – 3 times body weight with the knee flexed to the 90, during stair climbing and desent at a point when knee flexion reaches a maximum of 60 the peak value equals 3.3 of the body weight.



The large articular surfaces of the femur and the relatively small tibial condyle create problem as the femur begins to flex on the tibia . If the femoral condyles were permitted to roll posteriorly on the tibial condyles before much flexion had occurred. This would result in limitation of flexion or the femur would roll off the tibia.For the femoral condyles to continue to  roll with the increased flexion of the femur the condyles must simultaneously glide anteriorly on the tibial condyle to prevent them from rolling posteriorly off the tibial condyle.The first part of flexion of the femur from full extension(0-25) is primarily rolling of the femoral condyles on the tibia, bringing the contact of the femoral condyle posteriorly on the tibial flexion continues the rolling is accompanied by a simultaneous glide just sufficient to create a nearly pure spin of the femur. Extension of the knee from flexion occurs initially as a rolling of the femoral condyles on the tibial condyles ,displacing the femoral condyles anteriorly back to the neutral position after the initial forward rolling, the femoral condyles glide posteriorly just enough to continue extension of the femur as an almost pure spin. The motion of the menisci with flexion and extension are an important components of the motions. The menisci reduce friction and absorb forces of the large femoral condyles on the small tibial condyle,The menisci must remain beneath the femoral condyles to continue their function. failure of the menisci result in limitation of joint motion.




The incongurence of the femoral condyles result in a rolling and gliding of the condylar surfaces. The medial rotation of the femur that accompanies the final stages of knee extension is not voluntarily or produced by muscular forces it is reffered to as automatic or terminal rotation of the knee joint. It is also known as the locking mechanism or screw home mechanism of the knee. To initiate flexion the knee must first be unlocked that is medially rotated femur cannot flex in the saggital plane but must laterally rotate before flexion can proceed. A flexion force will automatically result in lateral rotation of the femur because the longer medial side will move before the shorter lateral side of the joint.

Q- angle: 

The pull of the quadriceps and the patellar ligament is commonly assessed by the Q angle of the knee. The Q angle is the angle formed between the line connecting the anterior superior iliac spine to the midpoint of the patella and a line connecting the tibial tubercle and the midpoint of the patella. An angle of 10-15 measured with the knee either in full extension or slightly flexed is normal .The increased angle among women has attributed to the fact that they have a wider pelvis , increased femoral anteversion and knee valgus. The Q angle is  measured with the knee in extension because excessive lateral forces may be a problem. A Q angle of 200 or more is considered to be abnormal.



A variety of mechanical , metabolic, genetic or constitutional insults may damage a synovial joint and trigger the need for repair. All the joints tissues (cartilage, bone, synovium , ligament, muscle)depend on each other for health and function. The OA process is metabolically active, involving new tissues production and remodeling of joint shape


It is a firm rubbery protein material covering the end of a bone. It acts as a cushion or shock absorber between the bones. When articular cartilage breaks down, this cushion is lost, and the bones will grind together. This causes the development of symptoms such as pain, swelling, bone spur formation and decreased motion. Osteoarthritis commonly affects weight bearing joints such as the knee, but it may affect any joint. Cartilage changes in OA are highly characteristics.

There is enzymatic degradation of the major structural components aggrecan and collagen principally by aggrecanase collagenase and stromelysin. The chondrocytes increase their production of matrix components and divide to produce clones or nests of metabolically active chondrocytes. Although the turnover of aggrecan components is increased  the concentration of aggrecan eventually falls. The decrease in size of the hydrophilic aggrecan molecules increases the water concentration and swelling pressure in cartilage, further disrupting the retaining scaffolding of type 2 collagen and making the cartilage vulnerable to load bearing injury. There is eventual fissuring of the cartilage surface( fibrillation), development of deep vertical clefts, localized chondrocyte death and decrease in cartilage thickness.

Cartilage loss is focal rather than widespread and usually restricted to the maximum load bearing part of the joint. The changes in OA cartilage encourage deposition of calcium pyrophosphate and apatite crystals. Damage to the ‘articular’ or hyaline cartilage can be as a result of sporting trauma, but is more commonly due to repetitive stresses over a long period of time. This is usually associated with habitual overuse of a joint for occupational or sporting purposes. In most individuals, the signs and symptoms do not appear until middle age, but the disease process starts much earlier. The hyaline cartilage is normally ultra smooth to allow friction free movement, but early damage to the superficial layers produces a frayed appearance.

The joint cartilage layer in osteoarthritis becomes thinner and eventually disappears entirely so that only raw  bone ends come in contact with each other. The grating of raw bone ends in direct contact causes pain and stiffness in the knee joint. The contours of the bone ends enlarge and bone spurs forms at the periphery of the knee joint. Joint capsule enlarges and becomes thicker. The joint cartilage damage may be restricted only to one knee joint compartment, as in this picture, or the whole knee joint may be affected by osteoarthritic changes. The complete loss of articular cartilage exposes the bone to stresses. It then undergoes intense osteogenic response. This phenomenon spreads towards the joint margins where unimpeded by compressive forces and perhaps encouraged by traction of capsular attachements it produces osseous outgrowth that extend into the capsule.


The bone immediately below the compromised cartilage increases its trabecular thickness. In some cases it reflects healed trabecular microfractures. Holes often develop possibly the result of small areas of osteonecrosis caused by the increased pressure in bones as the cartilage fails in its load transmitting function. At the margins of the joint there is fibrocartilage that then undergoes endochondral ossification to form osteophytes. Despite central and marginal new bone formation , with severe cartilage loss there may be attrition of bone as the two unprotected bone ends wear on each other. Such wear may ablate the trabeculae and lead to a smooth ,shiny, surface (eburnation) often with deep linear grooves. Bone remodeling and cartilage thinning slowly alters the shape or the OA joint increasing its surface. The bone surfaces become hard and polished as there is loss of protection from cartilage. In time, with more stress, this frayed surface evolves into cracks or ‘fissures’ in the articular cartilage, which can leave the underlying bone exposed. With continued wear the underlying bone takes on a polished appearance and eventually micro-fractures appear. The body’s natural reaction is to attempt to heal the micro-fractures by laying down more bone.


The joint cartilage layer in osteoarthritis becomes thinner and eventually disappears entirely so that only raw bone ends come in contact with each other. The grating of raw bone ends in direct contact causes pain and stiffness in the knee joint. The contours of the bone ends enlarge and bone spurs forms at the periphery of the knee joint. Joint capsule enlarges and becomes thicker. The quantity of joint fluid increases (effusion). Distended joint capsule makes the movements in the knee joint painful. Small fragments of damaged joint cartilage float in the joint fluid and cause secondary inflammation of the synovium (the inner lining of the joint space) with swelling and pain in the knee joint. The joint cartilage damage may be restricted only to one knee joint compartment, as in this picture, or the whole knee joint may be affected by osteoarthritic changes. In knee joints with changes restricted to only one knee joint compartment, it is most often the inner (medial) compartment that is damaged by OA, whereas other compartments may have still healthy cartilage. The presence of knee effusion, increased warmth CPPD crystals deposition and obesity are suggested risk factors. The capsule undergoes fibrous degeneration and low grade chronic inflammatory changes. The outer (lateral) compartment has healthy joint cartilage (light blue) and meniscus (dark blue).




It is at the knee that the predisposition to calcium pyrophosphate dehydrate (CPPD) crystals deposition by OA is most evident. Such coexistent crystals deposition may result in a more overt inflammatory component (stiffness, effusions)and supergradedacute of synovitis.




The capsule undergoes fibrous degeneration and low grade chronic inflammatory changes. The presence of knee effusion ,increased warmth CPPD crystals deposition deposition and obesity are suggested risk factors. The capsule undergoes fibrous degeneration and low grade chronic inflammatory changes. The bone surfaces become hard and polished as there is loss of protection from cartilage.  Articular cartilage: the complete loss of articular cartilage exposes the bone to stresses. It then undergoes intense osteogenic response. This phenomenon spreads towards the joint margins where unimpeded by compressive forces and perhaps encouraged by traction of capsular attachements it produces osseous outgrowth that extend into the capsule

Damage to the ‘articular’ or hyaline cartilage can be as a result of sporting trauma, but is more commonly due to repetitive stresses over a long period of time. This is usually associated with habitual overuse of a joint for occupational or sporting purposes. In most individuals, the signs and symptoms do not appear until middle age, but the disease process starts much earlier. The hyaline cartilage is normally ultra smooth to allow friction free movement, but early damage to the superficial layers produces a frayed appearance. In time, with more stress, this frayed surface evolves into cracks or ‘fissures’ in the articular cartilage, which can leave the underlying bone exposed.

With continued wear the underlying bone takes on a polished appearance and eventually micro-fractures appear. The body’s natural reaction is to attempt to heal the micro-fractures by laying down more bone. This leads to a thickening of the underlying layer of bone, which can be seen on x-ray. Another common feature on x-ray is the formation of bone cysts in the layer of bone beneath the joint surface, together with a flattening of the articular surfaces as the body attempts to spread the surface area over which forces are transmitted.

As well as changes in the articular cartilage and underlying bone, osteoarthritis produces soft tissue changes. As the joint becomes deformed by bony changes the ligaments which support the joint become stretched. There is also thickening and distension of the capsule that surrounds the joint and both of these features get progressively worse.


The ligaments undergo laxity




They undergo atrophy and wasting.




THE IDIOPATHIC OA – as the name idiopathic says, no one knows for sure what causes the destruction of the joint cartilage

THE SECONDARY OA  – the damage to the cartilage in the knee joint has a known cause such as previous fracture through the joint surfaces or damage to the meniscus or ligaments of the knee joint.



No one knows for sure the exact cause of osteoarthritis. There are two types of osteoarthritis : primary and secondary



The process  starts in the second decade of life but the degenerative diseases     are not apparent until middle age by 55-65yrs.


It is twice as common in women as in men over the age of 50.In men the order of the joint involved is hip, spine, ankle, shoulders, fingers. In women the order is knee, fingers, spine, hip, ankle, shoulders.




Herberden’s nodes may be inherited  as a single autosomal gene, sex influnced to be dominant in females Genetic factors are very important. Genes may affect collagen, one of the main building blocks of cartilage, or the way the bone reacts and repairs itself, or even the inflammatory process.




            Due to lack of exercise it is very common in obese people. Due to defective lubricating mechanism and uneven nutrition of the articular cartilge.


5)Poor Posture



The Secondary causes are


1)Trauma:it is more important risk factor in men and may result in unilateral OA. Most knee OA particularly in women is bilateral and symmertrical.


2)  Dislocations

3)  Infections like TB of knee joint




OA knee targets the patella-femoral and the medial tibiofemoral compartments of the knee. The pain is localized to the anterior aspect or medial aspect of the knee and upper tibia. Patello-femoral pain is usually worse going up and down stairs or inclines. Posterior knee pain suggests a complicating popliteal cyst. Commonly functional difficulties are prolonged walking, rising, from the chair, getting in or out the car or bending to put on shoes and socks. As the disease progresses  patient finds it difficult  to walk, to do her or his daily activities of daily living, climb stairs, unable to kneel or squatt.




 Due to inflammation in response to joint irritation caused by interference by loose bodies, cartilagenous debris engulfed by synovium. This appears with exercise but can be ‘walked off’.  Pain becomes severe as varus deformity increases.The types of pain are aching: fleeting and constant, refered :passing down the limb,sharp stabbing: loose bodies, throbbing: mainly at night. Pain with changes in weather are possible. Pain may be related to OA directly through increased pressure in subchondral bone, trabecular fractures , capsular distension and low grade synovitis or bursitis.

Pain in OA may be attributed to incongruent articulations of joint surfaces, periosteal elevation secondary to bone proliferation at the joint margin, abnormal pressures on sub-chondral bone, trabecular micro fractures and distention of the joint capsules.  Many patients will also experience a secondary synovitis especially when the knee is involved.


 the joint is often felt to creak and grate and swell from time to time especially  after any activity involving flexed position. Eg: kneeling and squatting As the disease progresses  patient finds it difficult  to walk, to do her or his daily activities of daily living, climb stairs, unable to kneel or squatt.


3)there will be swelling and inflammation of synovium the patient feels stiffness, tightness and reddness around the joint. Stiffness loosens quickly with rest



4)tenderness is elicited all round the joint


5)muscle spasm is present.



6)A jerky asymmetric antalgic gait is present where there is less time weight bearing on the painful side.


7)Weakness and wasting of the quadriceps muscle


8)Joint line or periarticular tenderness.



9)Young onset OA:


Some patients present with typical symptoms and clinical signs of OA but are younger than the expected(<45years).In most of the cases they have OA at a single joint such as the knee and the explanation of previous trauma is apparent in their history.



10) Changes in the weather may make a difference in some people. All joints have nerve endings which are sensitive to pressure. The nerve endings may respond to the drop in atmospheric pressure which occurs before it rains.



1.  Restricted movements.

2.  Palpable sometimes audible, coarse crepitus.

3.  Boney swellings around the joint margins. Deformity usually without instability

4.  Joint line or periarticular tenderness.

5.  Muscle wasting or weakness.

6.  No or only mild synovitis (effusion, increased warmth)

OA does not have a bilateral, symmetrical presentation. A single joint or any combination of joints on one individual may be affected. OA is not a systemic disease and it is therefore not associated with systemic complaints such as generalized morning stiffness, fever or loss of appetite.  Individual with OA may experience some stiffness in particular joints upon awakening that is similar to the stiffness felt when mobilizing the same joints after inactivity during the day but this stiffness does not last long.

CREPITUS is a common clinical finding.

List of symptoms of Osteoarthritis

The list of symptoms mentioned in various sources for Osteoarthritis includes:




The diagnosis and assessment of common OA are purely clinical.


A plain radiograph is the only useful but  non  essential  investigation. This may show one or more of the typical features of OA namely focal narrowing of joint space, marginal osteophyte, subchondral sclerosis, cysts, osteochondral loose bodies and deformity. Chondrocalcinosis may be an additional feature at the knee. The main use of a radiograph is to assess severity of structural changes, an issue if surgery is being considered. Standing AP radiograph are needed to assess tibio-femoral cartilage loss and a flexed skyline view is the best show the space between the bones narrowing as the cartilage thins, and changes in the bone such as spurs.



From the OA knees shows variable characteristics but is predominantly viscous with low turbidity. CPPD crystals may be identified up to 50%of knee OA fluids.





It is performed for other reasons often show an incidental finding, discrete increased uptake in OA joints due to bone remodelling.



Is also performed. MRI scan of the knee can be helpful. This shows the soft tissues (e.g. cartilage, tendons, muscles)  which cannot be seen on an x-ray. Sometimes, a MRI scan may be ordered to look at the knee more closely. A MRI scan is a special radiological test where magnetic waves are used to create pictures that look like slices of the knee. The MRI scan shows more than the bones of the knee. It can show the ligaments, articular cartilage, and menisci as well. The MRI scan is painless, and requires no needles or dye to be injected






It consists of conservative means and surgical means.


Includes reduced activity, weight loss, supports and braces, and physiotherapy are important initial steps in managing patients with osteo-arthritis of the knee. If these approaches fail, more aggressive treatment is warranted.


 Decreased physical activity can diminish symptoms or reduce the incidence of osteoarthritic flares in some patients. However, these advantages must be balanced against the negative aspects of decreased activity, including weight gain, diminished general fitness, and increased quadriceps weakness. It is preferable, and for many patients nonnegotiable, that they maintain or increase their level of physical activity. A pragmatic approach is to eliminate or decrease involvement in activities that are more likely to ignite an osteoarthritic flare, such as high-impact and pivoting sports. Safe exercise programs should be designed to be encouraged.Many people with osteoarthritis of the knee are overweight. Studies have shown that people who lose weight have fewer knee problems in the future improve function and conditioning levels.



Weight loss can ameliorate the severity of symptoms, but it is less certain whether weight loss can slow the rate of disease progression. Unfortunately, weight loss can be difficult to achieve and maintain. Many patients have pain and functional disability that limit or preclude exercise. For these patients weight loss is exceptionally difficult to achieve. They may require intervention to improve their knee pain before they can exercise at adequate levels to achieve weight loss. Low-impact alternatives, such as cycling or water-based exercises, should than those who do not. Being overweight is also bad for your general health and increases the risk of heart disease, strokes and diabetes. So you should eat a balanced, healthy diet and keep your weight as close as possible to the ideal for your height and age. Swimming can be a very good way of exercising and keeping fit as it causes little pain. Water supports the body’s weight so that little force goes through the joints as you exercise. Also, warm water relaxes muscles and joints and is very soothing, allowing joints to move more freely. Prescribed exercises in a hydrotherapy pool can help get muscles and joints working better, without undue pain. Supervised swimming in natural spa waters is an ancient treatment.  It is the exercise that helps rather than any healing properties of the water itself!






Some patients experience subjective improvement with the use of an elastic support around the knee. This approach must be used cautiously, if at all, in patients with a history of deep venous thrombosis or lower limb edema. Although the efficacy of this approach is not well established, it may enhance stabilizing inputs from articular and periarticular sensory receptors onto the motoneurons of muscles acting across the knee. Bracing can be effective in patients who have relatively focused unicompartmental medial or lateral osteoarthritis. Thus, valgus bracing is often used for varus knees in which osteoarthritis primarily involves the medial compartment. Less frequently, varus bracing may be indicated for lateral-compartment osteoarthritis associated with a valgus deformity. Unfortunately, even when a brace is prescribed and found to be efficacious, many patients stop using it after a short time.




Painkillers (such as paracetamol) and anti-inflammatory and paprika (capsaicin) creams to rub into the knee can help pain and stiffness. Some people find them more helpful than others. Anti-inflammatory drugs (NSAIDs) help some people more than paracetamol but they can cause stomach ulcers. Some new types of NSAIDs called COX-2s have the same beneficial effects but with less risk of stomach problems. However, all NSAIDs may cause other side-effects such as rashes, headaches and wheeziness. Sometimes an injection of steroids may help, either into a tender spot around the knee or even into the joint itself. The effect can last for several months. Injections of hyaluronan (Synvisc, Hyalgan, Durolane) may also help by supplementing the joint’s natural synovial fluid, although not everyone benefits from this type of treatment.



NSAIDS are a basic element in long term treatment having both analgesic and anti-inflamatory actions.  At lower doses the NSAID effect is analgesic, through the peripheral  inhibition of pro-inflamatory prostaglandin synthesis.  At higher doses, the effect is anti-inflamatory probably through both prostaglandin inhibition and alteration in macrophage and neutrophil function although NSAIDS provide symptomatic relief, they do not alter the underlined disease process.  The major serious and the most common side effects are gastro intestinal complaints ranging from nausea to gastro intestinal bleeding in ulcers.  Other possible side effects include dizziness headache doziness or tinnitus, kidney dysfunction and elevation of liver enzymes.

·        CAPSAICIN

In the past few years, topical capsaicin cream has been introduced as a symptomatic therapy for osteoarthritis. The neuropeptide substance P is present in A delta- and C-fiber sensory nerves. It has been implicated as a transmitter in articular pain pathways and is a putative contributor to joint inflammation. Application of capsaicin to A delta- and C-fibers depletes them of substance P, blocking subsequent intraneuronal axonal transport and synthesis of substance P.16 Thus, capsaicin can potentially ameliorate symptoms of osteoarthritis through 2 mechanisms: by attenuating transmission in articular pain pathways and by diminishing joint inflammation. Studies support the safety and efficacy of capsaicin for treating osteoarthritis of the knee.Unfortunately, people in warm climates may have difficulty using capsaicin. They may experience an extreme burning sensation when using capsaicin and exercising strenuously in a hot environment.




                      The role, if any, of antidepressants such as amitriptyline in managing symptomatic osteoarthritis of the knee is unclear. Some patients with osteoarthritis of the knee exhibit chronic pain behavior.


                          Chondroitin and glucosamine have become popular as putative symptomatic and disease-modifying therapies for osteoarthritis of the knee. It is hypothesized that these important constituent components of cartilage matrix can be ingested, enter plasma, cross the blood-synovial fluid barrier, and enter synovial fluid in sufficient concentrations to provide analgesia and promote cartilage healing. The mechanisms, if any, underlying these alleged therapeutic effects remain undiscovered. Some clinical trials data are starting to become available. Given their widespread use by patients, it is fortunate that these products appear to be safe, and they can be a useful adjunct, especially in patients who cannot tolerate NSAIDs


                          Hyaluronan (HA) in both articular tissues and synovial fluid plays an important role in contributing to joint homeostasis and maintaining normal joint function. In osteoarthritis, the molecular weight and concentration of HA is diminished. This has led to the concept of visco supplementation, in which pathologic synovial fluid is aspirated and HA-based products are injected into the articular space in order to restore HA concentration and molecular weight to relatively normal levels. Therapeutic benefit is believed to occur by restoring the viselastic, antinociceptive, anti-inflammatory, and autoregulatory functions of HA in synovial fluid.

Clinical studies of HA-based products have demonstrated clinical benefit for about 70% of patients in a heterogenous osteoarthritis population. Duration of improvement ranges from months to years. Two types of HA products are available for treating osteoarthritis of the knee: low-molecular weight HAs and high-molecular weight hylan (cross-linked HA). Hylan closely replicates the molecular weight of the HA found in normal synovial fluid.

HA-based products are safe. Local inflammatory reactions typically occur after 3% of injections. These are usually mild and self-limited. Marked reactions usually respond well to aspiration and corticosteroid injection. Severe reactions mimicking a septic joint occur at a rate of about 1 in 500 injections. After obtaining a Gram stain and cultures to rule out infection, response to aspiration and corticosteroid injection is usually dramatic. Systemic reactions are rare.

Injection technique is critical. It is essential to ensure that the HA is injected intra-articularly. There is evidence that 30% of putative knee joint injections miss the intra-articular space. In the case of corticosteroid injections, this may not greatly affect efficacy. However, with viscosupplementation, if the HA product is not injected into the joint space, efficacy diminishes and the incidence of local flare reactions increases. Before injection it is also critical to aspirate as much of the pathologic osteoarthritic synovial fluid as possible so the injected HA-based replacement is not diluted. Sometimes an injection of steroids may help, either into a tender spot around the knee or even into the joint itself. The effect can last for several months. Injections of hyaluronan (Synvisc, Hyalgan, Durolane) may also help by supplementing the joint’s natural synovial fluid, although not everyone benefits from this type of treatment.Experience with viscosupplementation has been encouraging. However, many unresolved issues surround the use of HA products.

                      These include developing optimal dosing regimens, determining the most appropriate positioning in treatment algorithms, assessing their role in osteoarthritic joints other than the knee, exploring efficacy in inflammatory arthritides, and determining the importance of molecular weight in selecting HA products.

                                 It has been argued that HA products have enhanced efficacy as their molecular weight increases. Both in vitro and in vivo animal evidence supports this view.A recent clinical study35 found that the high-molecular weight HA product hylan G-F 20 was more effective than a low-molecular weight HA product in relieving the pain of osteoarthritis of the knee. Although these data are suggestive, a definitive answer to this question awaits further clinical trials that directly compare these 2 classes of HA products.


Sometimes, if your knee locks, ‘keyhole’ surgery techniques are used to ‘wash out’ loose fragments of bone and other tissue from the joint. This is called arthroscopic lavage and is sometimes carried out during the course of a diagnostic arthroscopy. Rarely, additional procedures may be carried out – such as smoothing the surfaces of the joint, removing flaps of damaged hard cartilage, and trimming torn soft cartilage. This is called debridement. These techniques may offer pain relief in the early stages of osteoarthritis, but they cannot repair the damage caused by the osteoarthritis.                                                                                                                                                        




Physiotherapy assessment is divided into subjective and objective type of assessment.

Subjective: Which the patient reveals himself.
Objective: which is elicited by the therapist.
Subjective examination:
Chief complaints:  

Pain, Swelling, Stiffness.

Previous history:

This should include any problem in the past illness like diabetes, hypertension, rheumatism, asthma, allergy, tuberculosis etc.,

Treatment history:

Enquire about all the treatment, the patient has had including medicines like non-steroid anti-inflammatory drugs, steroid, physiotherapy plaster, orthoses, intra auricular steroid injections etc.,

Family history:

Enquire about the general family health occurrence of any familial or hereditary disease and support from the family in terms of Psychological and financial aspect.

Personal history:

Alcohol consumption, smoking habit and sexual life must be recorded.

Objective examination

Vital signs:

·        Temperature-37 o (98.6 o F).

·        Respiratory rate-12-20 per minute.

·        Pulse rate-70 times per minute.

On palpation:

The therapist elicits skin temperature tissue elasticity, crepitus, tenderness, soft tissue/joint stiffness.

On observation:

The therapist looks for oedema, muscle wasting, deformity, condition of skin.


The gait must be noted.

Range of motion:

Active movement should be tested including squatting, standing,  hopping.Active range of motion is measured with the help of goniometer.

Examination of power:

Endurance, tone and volume of the muscle groups related to the involved joint are systematically recorded



Assessment of deformity:

It is extremely important to measure the degree of deformity, the deformity may be fixed or dynamic when exposed to compression.

Functional assessment:

The influences of the disease on the functional performance of the patient are examined and recorded on a functional evaluation chart.

Visual Analog Scale (VAS):-
                            20        40       60       80        100
Knee rating scale for pain and functions:
-- Pain free standing and long walk- 50.
-- Mild pain, painless walking up to 1 km 40.

-- Considerable pain on long standing/walking 20.

-- Pain free up to less than 1/2km.-20.

-- Considerable pain, walking confined to indoor only-10.

-- Severe pain on standing/walking or even at rest-5.

-- Unable to walk-0.



1)Flexibility tests.


2)Patellar tap test.


3)Fluid displacement test.


4)Hydraulic impulse test.


5)Tests for meniscus instability


6)Tests for ligamentous instability.



                      General and physiotherapy management along with patient education regarding the usage of assistive devices for example a knee brace, may reduce forces on damaged joints.Referral to dietician may be important when there is obesity.




1) To control pain.


2) To decrease the swelling.


3)  To increase the blood supply.


4)  To prevent further strain or damage to affected joint.


5)  To improve movement.


6)  To correct the deformity and contracture.


7) . To improve muscle power.


8)  To maintain or improve functional independence.






Modalities to control pain




Two types of TENS are used.

A.) High-TENS.

B.) Low-TENS.

During acute stage high-TENS is used. During chronic stage low-TENS is used.



1)It is used for its analgesic and circulatory effects.

2)Currents between 0-10Hz are used to provide muscle stimulation  by a current which is more comfortable than faradism.

3)Four pole vector method is used. 2 electrodes are kept above the knee joint and 2 electrodes are kept below the knee joint.


It is effective in some patients especially in reducing a dull ache.the localizes increase in arterial blood flow may improve the nutrition to the joint cartilage.


Superficial or deep heat will relieve discomfort by reducing the protective muscle spasm. 

Superficial heat infra red radiation, heat pad or heat pack con bring relief to patients where there is muscle spasm.


1)Direct pouring method or dip and wrap method or applying with lint cloth may be used.

2)It is given prior to exercise programme.


This is indicated it pain is centered on peri-articular soft tissues. This is very useful for treating chronic swellings as it loosens scar tissue and gains pain relief,especially deep aching.


It has got deeper effects


1)It penetrates in to the joint.


2)It helps in healing process.


3)Pad-electrodes or disc electrodes are used.


4)Contra-planar method is used.


5)One electrode is used placed on the medial side and other one on  the lateral side.


6)Wider spacing method is used.



               This is used if there is acute pain and swelling at the knee when a loose body flake of cartilage becomes trapped between joint surfaces.

1)It is useful if there is acute pain and swelling at the knee.


2)Cold  can lessen pain by numbing the local tissues.


3)It may be applied in the form of a reusable pack or ice.

4)Ice and cold packs never should be placed directly on the skin as they are likely to cause skin damage.

5)Ice and cold packs should be wrapped in a towel before they are applied.


                 The warmth of the water or its buoyancy are helpful in relieving pain particularly when the weight bearing joints like knees are affected.


1.The identification of activities which produce strain  followed by  reduction or elimination of them is obviously the best method.

2.Improvement of posture, correcting leg length inequality by a shoe rise may also be required.



1)Exercise programme should be simple.

2)It should be developed on the basis of the normal  kinematics to regain the correct mechanism of knee joint.

3)Exercise programme includes.

a)Isometric exercises: This is exercise in which muscles are tensed for a period without actually moving them. It can be performed without actually bending a painful joint. As muscles are exercised against resistance, their size and power will increase.

Quadriceps (thigh muscle) exercises

The most important thing is to choose exercises which you can do regularly.The easiest one to do is when sitting down in a chair.

  1. Straight-leg raise: sitting Get into the habit of doing this every time you sit down. Sit well back in the chair with a good posture. Straighten and raise the leg, hold it for a slow count to 10, then slowly lower it. Repeat this several times with each leg – at least 10 times with each. If this can be done easily, repeat the exercises with a weight on the ankle (buy ankle weights from a sports shop or improvise, for example with a tin of peas in a carrier bag wrapped round the ankle).
  2. Straight-leg raise: lying Get into the habit of doing straight-leg exercises in the morning and at night while lying in bed. With one leg bent at the knee, hold the other leg straight and lift the foot just off the bed. Hold for a slow count of 5 then lower. Repeat with each leg 5 times every morning and evening.
  3. Muscle stretch At least once a day when lying down do the following exercise. First, place a rolled-up towel under the ankle of the leg to be exercised. Then bend the other leg at the knee. With the straight leg, use your leg muscles to push the back of the knee firmly towards the bed or the floor. Hold for a slow count of 5. Repeat with each leg 5 times. Not only does this exercise help to strengthen the quadriceps muscles, but also it prevents the knee from becoming permanently bent.
  4. Clenching exercises During the day, whether standing or sitting, get     into the habit of clenching and releasing the quadriceps muscles. By constantly stimulating the muscles, they become stronger.






Sit on the floor with your legs outstretched and your hands supporting  you lightly at the side.


Push your knees down to the floor, tightening the quads as you do so. Make sure your kneecaps go tight. Keep it for a count of five seconds.


Relax and Repeat the whole routine 10 times.





Lie or sit with a rolled towel underneath the knees. Relax the head.



Straighten the knees, bringing the heels up off the floor. Keep them  up for a count to five


Relax. Repeat routine 10 times






Lie on your tummy with a rolled towel under your ankles.



Force your leg straight. The knees will lift up off the floor. Count to ten, maintaining the contraction.



Relax and repeat the whole routine for 10 times.

b) Stretching exercise: Also called ROM exercise, it helps to maintain joint flexibility and reach. It includes anything that puts a joint through its fullest ROM .

Stretching exercises are given to hamstrings.


1)Hamstring Stretch, Supine, 10 Repetitions

Lie on your back.


Bend your hip, grasping your thigh just above the knee.

Slowly straighten your knee until you feel the tightness behind your knee. Hold for 5 seconds. Relax and repeat 10 times.

Repeat with the other leg. If you do not feel this stretch, bend your hip a little more, and repeat. No bouncing! Maintain a steady, prolonged stretch for the maximum benefit.

2)Hamstring Stretch, Supine at Wall, and 10 Repetitions

Lie next to A doorway, with one leg extended.

Place your heel against the wall, and, with your knee bent, move your hips toward the wall. Now begin to straighten your knee. When you feel the tightness behind your knee, hold for 5 seconds.

Relax and repeat 10 times. The closer you are to the wall, the more intense the stretch.

Repeat with the other leg.

c) Aerobic exercise: This is endurance-building exercise that improves cardiopulmonary fitness. For most individuals with osteoarthritis, the best aerobic exercises are-

·        Swimming.

·        Walking on level ground.



They restore mobility and improve circulation.

Muscle strengthening:

For quadriceps:

The patient is in half crook lying . the weight is attached to the straight leg.instructions are given to the patient to keep knee straight and to lift the leg to the level of the other thigh. The sequence is repeated 10 lifts for 3 times .the main cause is to strengthen the muscle without the joint surfaces being moved under the load. 

Muscle mobilization:

Relaxed passive movements of knee joint:

1) When patient is lying, the therapist in walk stand position gives support under the thigh with one hand and with the other hand grasps round the ankle and gives traction. The joint is then moved into flexion and the therapist ‘s hand glides in front of the knee to give overpressure at the end of the movement.

2) When the patient is in side lying, one of the leg is placed on the plinth and the other should be moved is supported throughout the movement in the hands and hence the knee is flexed and extended.

 Assisted and assisted-resisted exercises

1) When the patient is in side lying, with the limb supported in the hands or on the surface of a plinth The pattern of movement used should be that of the withdrawal of the leg followed by thrust