Arthritis

KNEE PAIN.....

KNEE JOINT ANATOMY The knee joint is the largest synovial (lined by synovial membrane) joint of the body. It is a major weight bearing joint of the body…

Dr. Shweta Bairagi · 26 May 2011

KNEE JOINT ANATOMYThe knee joint is the largest synovial (lined by synovial membrane) joint of the body. It is a major weight bearing joint of the body and is made of three bones. On the top is the thigh bone (femur) below it the shin bone (tibia) and in the front is the knee cap (patella).Keeping all these bones in place are various ligaments (tough band or cord like structures), muscles and the joint capsule (tough flexible fibrous structure that surrounds the joint).The part of the femur that forms the knee joint is expanded side ways and behind to form two oval structures called condlyes. Similarly the part of the tibia forming the knee is expanded and forms two condyles that articulate with the corresponding femur condyles. The one on the outer side is called the lateral condyle and the one on the inner side is called the medial condyle On the front the patella articulates with the femur.Clinicians also divide the knee joint into compartments.The medial condyles form the medial compartment. The lateral condyles form the lateral compartment.Anterior compartment is between the patella and femur.Joint BasicsThe point at which two or more bones are connected is called a joint. In all joints, the bones are kept from grinding against each other by padding called cartilage. Bones are joined to bones by strong, elastic bands of tissue called ligaments. Tendons are tough cords of tissue that connect muscle to bone. Muscles work in opposing pairs to bend and straighten joints. While muscles are not technically part of a joint, they're important because strong muscles help support and protect joints.Tendons and LigamentsThe quadriceps tendon connects the quadriceps muscle to the patella and provides thepower to extend the leg. Four ligaments connect the femur and tibia and give the jointstrength and stability:The medial collateral ligament (MCL) provides stability to the inner (medial)part of the knee.The lateral collateral ligament (LCL) provides stability to the outer (lateral) partof the knee.• The anterior cruciate ligament (ACL), in the center of the knee, limits rotationand the forward movement of the tibia.The posterior cruciate ligament (PCL), also in the center of the knee, limitsbackward movement of the tibia.Other ligaments are part of the knee capsule, which is a protective, fiber-likestructure that wraps around the knee joint. Inside the capsule, the joint is linedwith a thin, soft tissue called synovium.The bone ends are covered with cartilage (tough, smooth and resilient structure). Function of the cartilage is to provide a smooth surface, for the bones to move easily over one another. It also acts as a shock absorber.The knee is a hinge joint , meaning that it allows movement in one plain only.Flexion (bend) and extension (straighten the knee). Though slight amounts of rotation and translation also occur.Internally the whole surface of this joint (excluding cartilage), is covered with a thin membrane (sheet or film like) structure called synovium . The function of synovium is to secrete a fluid, that lubricates the joint and provides nourishment to the avascular (having no blood supply) cartilage.Four main ligaments stabilize this joint. Medially (on the inner side) the medial collateral ligament . Laterally (on the outer side) the lateral collateral ligament . These ligaments stabilize the knee against angulation (tend to wedge open the joint) and translation (tend to slide the bones in opposite direction) forces.The other two ligaments are the anterior and posterior cruciate ligaments . There main function is to stabilize the joint against translation forces.Muscles acting on this joint are extensors (straighten) and flexors (bend the joint). Extensors include the Quadriceps muscle. Flexors include Semitendenosus, Semimembranosus and the Biceps femoris (collectively called Hamstring muscles).This joint is also surrounded by small sac like structures, that have an inner lining of synovial membrane called bursae . The function of these is to allow, smooth movement of various ligaments and tendons (cord like structures that attach muscles to bone) over bone.Knee pain is the most common musculoskeletal complaint that brings people to their doctor. With today’s increasingly active society, the number of knee problems is increasing.A. Distal FemurLateral and Medial CondylesArticulate with tibiaIntercondylar fossaPatellar articular surfaceB. PatellaC. Proximal End of TibiaLateral and Medial tibial condylesArticulates with femoral condylesIntercondylar eminenceIntercondylar area - anteriorFound anterior to the intercondylar eminenceProvides attachment for anterior cruciate ligamentIntercondylar area - posteriorFound posterior to the intercondylar eminenceProvides attachment for posterior cruciate ligamentTibial tuberosityPoint of insertion od the ligament of the patellaD. Fibula - proximal en dHead of fibula articulates with the lateral tibial condyleNot involved in weight bearing during standingProvides attachments for musclesII. ALIGNMENT OF THE KNEEA. Normal AlignmentSlight valgus positionAngle between longitudinal axis of femur and tibia is 1700 opened laterallyB. Q angle - is a measure of the axis of pull of the quadriceps tendon and that of the ligament of the patella. The former is measured by a line drawn from the ASIS to center of patella. The latter is determined by a line drawn from the tibial tuberosity to the center of the patella. The normal Q angle is between 15 -200. This angle is somewhat greater in females than males.Abnormal AlignmentGenu Valgum ( Knock Knee)Tibia abducted with respect to femurGenu Varum (Bow Leg)Tibia adducted with respect to femurIII. CAPSULAR LIGAMENTSA. FunctionStrengthen the fibrous capsuleB. Strengthening Anterior Aspect of Knee JointQuadriceps TendonPasses over and partially attaches to patellaContinues to insert onto tibial tuberosity as the Patellar LigamentPatellar RetinaculaExtensions of fascia from the quadriceps musclesAttach patella and patellar ligament to tibial and femoral condylesC. trengthening the Posterior Aspect of the Knee JointOblique Popliteal LigamentDerived from the tendon of the semimembranosus muscleArcuate Popliteal Ligament. Derived from the tendon of the biceps femoris muscleD. Strengthening the Medial Aspect of the Knee JointTibial ( Medial ) Collateral LigamentAttaches from medial femoral condyle superiorly to the media tibial condyle inferiorlyAttaches to medial meniscusForms part of the capsule and strengthens capsule mediallyE. Lateral Aspect of the Knee JointFibular ( Lateral ) Collateral Ligament. Attaches from lateral femoral condyle superiorly to head of fibula inferiorlyDoes not attach to lateral meniscusNot part of the fibrous capsuleDoes not strengthen the fibrous capsulecapsule weak laterallyIV. INTRACAPSULAR LIGAMENTSA. Anterior CruciateArises from anterior intercondylar area to tibiaAttaches to medial surface of lateral femoral condyleResists anterior movement of tibia on femur or posterior movement of femur on tibiaAnterior Draw SignIntegrity of anterior cruciate ligamentB. Posterior CruciateArises from posterior intercondylar area to tibiaAttaches to lateral surface of medial femoral condyleResists posterior movement of tibia on femur or anterior movement of femur on tibiaC. Posterior Meniscofemoral LigamentContinuation of lateral meniscus attaching to the posterior cruciate ligamentV. MENISCIA. PropertiesComposed of fibrocartilageCover the superior surface of the tibial condylesAdapt the shapes of the tibial condyles to provide a better fit between tibial and femoral condylesB. Lateral MeniscusCovers the surface of the lateral tibial condyleOval shapeThicker, shorter and more closed shaped than medial meniscusMobileC. Medial MeniscusCovers medial tibial condyleC. shapedLarger, thinner and more opened shaped than lateral meniscusLess mobileProvides attachment for medial collateral ligamentMore likely to be injured when medial collateral ligament is damagedAbduction injuryi) Caused by lateral blow to kneeii) Stresses medial collateral ligamentiii) Can lead to damage of ligament and medial meniscusD. Transverse Ligament of the Knee Continuation anteriorly of fibers from the lateral meniscus to the medial meniscusCoronary LigamentsExtensions of the fibrous capsuleAttach the menisci to the tibial condylesVI. LOCKING OF THE KNEE JOINTA. FunctionPermits standing upright with little expenditure of energy in the form of muscle contractionVII. UNLOCKING OF THE KNEE JOINTA. PropertiesLateral rotation of the femur on the tibiaBrought about by action of the Popliteus MuscleArises from lateral femoral condyleInserts into the posterior part of the tibiaPulls the lateral condyle posteriorly laterally rotating the femurWhat Do the Knees Do? How Do They Work?The knees provide stable support for the body and allow the legs to bend and straighten. Both flexibility and stability are needed for standing and for motions like walking, running, crouching, jumping, and turning. Several kinds of supporting and moving parts, including bones, cartilage, muscles, ligaments, and tendons, help the knees do their job. Any of these parts can be involved in pain or dysfunction.Knee pain can be related to overuse or gradual onset, or acute / sudden onset. With gradual onset small stresses are repeated a large number of times without allowing adequate recovery, for example running too much too soon, or excessive jumping.injuries can be acute where the injury is caused by an impact or twisting such as an anterior cruciate ligament injury. An overuse injury can also be considered to be acute if it is painful or inflammed.Running and Knee PainRunners are very prone to knee pain. The most common causes of knee pain in runners are:Iliotibial Band / Runners KneePatella Pain SyndromePatella Tendon PainPoplieus InjuryKnee Joint InjuriesAnterior cruciate ligament injury, Medial ligament sprain, Lateral ligament sprain, Posterior cruciate ligament injury....Anterior (Front of Knee Injuries)Jumpers knee (patella tendinitis), Patellofemoral pain syndrome, Chondromalacia Patellae, Housemaids knee.Medial (Inside Knee Pain)Medial Cartilage Meniscus Injury, Medial Ligament Sprain, Osteoarthritis of the knee, Synovial Plica / Patella Plica...Lateral (Outside of Knee Pain)Iliotibial band friction syndrome (runners knee), Patellofemoral instability , Lateral cartilage injury, Lateral collateral ligament injuries...Posterior (Back of the Knee Pain)Posterior cruciate ligament injury, Bakers Cyst, Hamstring tendon strain...Acute PainAcute patella injury, Patella dislocation, Patella tendon rupture.Causation of Knee ProblemsThere are two general kinds of knee problems: mechanical and inflammatory.Mechanical Knee Problems: Some knee problems result from injury, such as a direct blow or sudden movements that strain the knee beyond its normal range of movement. Other problems, such as osteoarthritis in the knee, result from wear and tear on its parts.Inflammatory Knee Problems: Inflammation that occurs in certain rheumatic diseases, such as rheumatoid arthritis and systemic lupus erythematosus, can damage the knee.How Are Knee Problems Diagnosed?Doctors use several methods to diagnose knee problems.Medical history --The patient tells the doctor details about symptoms and about any injury, condition, or general health problem that might be causing the pain.Physical examination --The doctor bends, straightens, rotates (turns), or presseson the knee to feel for injury and discover the limits of movement and the location of pain. The patient may be asked to stand, walk, or squat to help the doctor assess the knee's function.Diagnostic tests --The doctor uses one or more tests to determine the nature of aknee problem.o X ray (radiography)-- An x-ray beam is passed through the knee toproduce a two-dimensional picture of the bones.o Computerized axial tomography (CAT) scan --X rays lasting a fractionof a second are passed through the knee at different angles, detected by ascanner, and analyzed by a computer. This produces a series of clearcross-sectional images ("slices") of the knee tissues on a computer screen.CAT scan images show soft tissues such as ligaments or muscles moreclearly than conventional x rays. The computer can combine individualimages to give a three-dimensional view of the knee.o Bone scan (radionuclide scanning) --A very small amount of radioactivematerial is injected into the patient's bloodstream and detected by ascanner. This test detects blood flow to the bone and cell activity withinthe bone and can show abnormalities in these processes that may aiddiagnosis.o Magnetic resonance imaging (MRI) --Energy from a powerful magnet(rather than x rays) stimulates knee tissue to produce signals that aredetected by a scanner and analyzed by a computer. This creates a series ofcross-sectional images of a specific part of the knee. An MRI isparticularly useful for detecting soft tissue damage or disease.o Arthroscopy --The doctor manipulates a small, lighted optic tube(arthroscope) that has been inserted into the joint through a small incisionin the knee. Images of the inside of the knee joint are projected onto atelevision screen. While the arthroscope is inside the knee joint, removalof loose pieces of bone or cartilage or the repair of torn ligaments andmenisci is also possible.o Biopsy --The doctor removes tissue to examine under a microscope.Knee Injuries and Problems……ArthritisWhat Is Arthritis of the Knee?Arthritis of the knee is most often osteoarthritis. In this disease, the cartilage in the joint gradually wears away. In rheumatoid arthritis, which can also affect the knees, the joint becomes inflamed and cartilage may be destroyed.* Arthritis not only affects joints; it can also affect supporting structures such as muscles, tendons, and ligaments.Osteoarthritis may be caused by excess stress on the joint from deformity, repeatedinjury, or excess weight. It most often affects middle-aged and older people. A young person who develops osteoarthritis may have an inherited form of the disease or may have experienced continuous irritation from an unrepaired torn meniscus or other injury .Signs and DiagnosisSomeone who has arthritis of the knee may experience pain, swelling, and a decrease inknee motion . A common symptom is morning stiffness that lessens as the person movesaround. Sometimes the joint locks or clicks when the knee is bent and straightened, butthese signs may occur in other knee disorders as well. The doctor may confirm the diagnosis by performing a physical examination and examining x rays, which typically show a loss of joint space. Blood tests may be helpful for diagnosing rheumatoid arthritis, but other tests may be needed too. Analyzing fluid from the knee joint may be helpful in diagnosing some kinds of arthritis.Injuries to the MeniscusWhat Causes Injuries to the Meniscus? The meniscus is easily injured by the force of rotating the knee while bearing weight. A partial or total tear may occur when a person quickly twists or rotates the upper leg while the foot stays still (for example, when dribbling a basketball around an opponent or turning to hit a tennis ball). If the tear is tiny, the meniscus stays connected to the front and back of the knee; if the tear is large, the meniscus may be left hanging by a thread of cartilage. The seriousness of a tear depends on its location and extent.Generally, when people injure a meniscus, they feel some pain, particularly when theknee is straightened. If the pain is mild, the person may continue moving. Severe pain may occur if a fragment of the meniscus catches between the femur and the tibia. Swelling may occur soon after injury if blood vessels are disrupted, or swelling may occur several hours later if the joint fills with fluid produced by the joint lining (synovium) as a result of inflammation. If the synovium is injured, it may become inflamed and produce fluid to protect itself. This makes the knee swell. Sometimes, an injury that occurred in the past but was not treated becomes painful months or years later, particularly if the knee is injured a second time. After any injury, the knee may click, lock, or feel weak. Although symptoms of meniscal injury may disappear on their own, they frequently persist or return and require treatment.DiagnosisIn addition to listening to the patient's description of the onset of pain and swelling, the doctor may perform a physical examination and take x rays of the knee. The examination may include a test in which the doctor bends the leg, then rotates the leg outward and inward while extending it. Pain or an audible click suggests a meniscal tear. An MRI may be recommended to confirm the diagnosis. Occasionally, the doctor may use arthroscopy to help diagnose and treat a meniscal tear.Warming up the joint by riding a stationary bicycle, then straightening and raising the leg (but not straightening it too much).Extending the leg while sitting (a weight may be worn on the ankle for this exercise).Raising the leg while lying on the stomach.Exercising in a poolLigament InjuriesAnterior and Posterior Cruciate Ligament InjuriesInjury to the cruciate ligaments is sometimes referred to as a "sprain." The ACLis most often stretched or torn (or both) by a sudden twisting motionThe PCL is most often injured by a direct impact, such as in an automobile accident or football tackle.Symptoms and DiagnosisInjury to a cruciate ligament may not cause pain. Rather, the person may hear a popping sound, and the leg may buckle when he or she tries to stand on it. The doctor may perform several tests to see whether the parts of the knee stay inproper position when pressure is applied in different directions. A thoroughexamination is essential. An MRI is very accurate in detecting a complete tear,but arthroscopy may be the only reliable means of detecting a partial one.Medial and Lateral Collateral Ligament InjuriesThe MCL is more easily injured than the LCL. The cause is most often a blow tothe outer side of the knee that stretches and tears the ligament on the inner side of the knee. Such blows frequently occur in contact sports like football or hockey.Symptoms and DiagnosisWhen injury to the MCL occurs, a person may feel a pop and the knee maybuckle sideways. Pain and swelling are common. A thorough examination isneeded to determine the kind and extent of the injury.Tendon Injuries and DisordersWhat Causes Tendinitis and Ruptured Tendons?Knee tendon injuries range from tendinitis (inflammation of a tendon) to a ruptured (torn)tendon. If a person overuses a tendon during certain activities such as dancing, cycling, orrunning, the tendon stretches like a worn-out rubber band and becomes inflamed. Also,trying to break a fall may cause the quadriceps muscles to contract and tear thequadriceps tendon above the patella or the patellar tendon below the patella. This type of injury is most likely to happen in older people whose tendons tend to be weaker.Tendinitis of the patellar tendon is sometimes called jumper's knee because in sports thatrequire jumping, such as basketball, the muscle contraction and force of hitting the ground after a jump strain the tendon. After repeated stress, the tendon may become inflamed or tear.Symptoms and DiagnosisPeople with tendinitis often have tenderness at the point where the patellar tendon meets the bone. In addition, they may feel pain during running, hurried walking, or jumping. A complete rupture of the quadriceps or patellar tendon is not only painful, but also makes it difficult for a person to bend, extend, or lift the leg against gravity. The doctor may use an MRI to confirm a partial or total tear.COMMON KNEE PROBLEMSMeniscus tears : Sudden twists can tear the meniscus cartilage causing pain. The knee may lock or give away when stressed by running, kneeling or squatting.Ligament tears : Twisting injuries, even those that seem minor can injure ligaments. Patella Problems: Tracking problems with the kneecap, which can be traumaticOsteoarthritis : The cartilage in the patient’s knee joint gradually deteriorates due to wear and tear, genetic predisposition, and primary arthritic diseases. This results in pain and aching in the knee joint when the patient moves the knee or puts weight on it .Osteoarthritis affects the knee joint by damaging the cartilage (Cartilage is made up of a protein substance that acts as a ?cushion? between the bones of the joints) in the knee joint. The cartilage in the knee joint slowly degenerates. In advanced cases, it may disappear and the bones start rubbing against each other and causing more pain. When bones start to rub against each other, bony growth may occur around the joints.In the initial stages of knee osteoarthritis, one may simply feel deep aching in the knee joint. As it advances, common symptoms include pain that is worse after an exercise session or weight bearing, swelling in the joint, limited movement of the knee joint, stiffness following periods of inactivity such as sleeping or sitting; cracking or grating sounds in the knee joint. As the damage to the knee joint advances, the joint may become less movable and pain may occur even when the joint is at rest and can keep the person awake throughout of the night.The real cause of osteoarthritis is not very clear. Medical researchers believe that it is due to a combination of factors that include aging, injury to the joint or stress, being overweight and genetic factors.Popliteal cysts : (also called a Baker’s Cyst) Occurs when the membrane that lines the joint becomes inflamed. Bending the knee may be painful because bulging cysts may form behind the knee due to excess fluid produced by the joint.Tendonitis :Inflammatory problems with various tendons around the knee that create discomfort with activities.The knees are the most easily injured part of the body. The largest and most complicated joint, the knee is used for everything from standing up, sitting, to walking, running, etc. It's a weight-bearing joint that straightens, bends, twists and rotates. All this motion increases your risk of acute or overuse knee injuries. Acute knee injuries (including torn ligaments and torn cartilage) are often caused by twisting the knee or falling. Sports that involve running and jumping and sudden stopping and turning, such as soccer, basketball, volleyball, tennis, and baseball, as well as contact sports such as football, wrestling, and hockey increase the risk of an acute knee injury. But more common than sudden knee injuries are injuries caused by overuse Overuse knee injuries (including muscle strain, tendonitis and bursitis) may develop gradually over days or weeks. Pain is often mild and intermittent in the beginning and worsens over time. When muscles and tendons are stressed even slightly beyond their capabilities, microscopic tears occur. (Inflammation, which is part of the healing process, is what causes the pain). These tears must be given a chance to heal before subjected to the same activity to avoid overuse injury. Knee pain is commonly caused by doing too much too soon when you haven't exercised for a long period of time - especially high-impact aerobics; walking, running or jumping on hard surfaces or uneven ground; excessive running up and down stairs (When you walk upstairs you are putting pressure on your knees that is equivalent to four times your body weight, when running up the stairs it can be eight times your body weight).Knee osteoarthritis is a common cause of knee pain. The risk increases with age. Osteoarthritis is a form of arthritis involving degeneration of the cartilage. Exercise is vital to maintain strength and flexibility of muscles supporting the knee, which reduces the stress on the knee joint.Runners knee (also called patellofemoral pain or anterior knee pain) is a common cause of knee pain in young people (not just in runners). The pain is usually diffuse pain behind the kneecap. Symptoms often worsen after climbing stairs, jumping, running, or after a period of sitting. Caused by poor tracking of the kneecap, appropriate exercises prescribed by a doctor or physical therapist is the main treatment in correcting runners knee. Stay away from high-impact activity if you have this condition.Prevent knee pain by keeping the muscles that support your knees strong and flexible. Start out slowly. Walk before you run - before you engage in a strenuous high impact activity such as jogging or running, try walking for a week. If walking causes knee pain, you shouldn't be running. Warm up before working out. Give your body a chance to recover from exercise. If you do high impact activities take every other day off. Avoid running up and down stairs and full squats. Doing knee exercises to strengthen and stretch the muscles that support the knee are vital for knee pain and injury prevention. Proper footwear is also important, especially if walking or running on hard surfaces. Keep your weight under control. Reducing one's weight reduces stress upon the knee.Other Knee InjuriesWhat Is Osteochondritis Dissecans?Osteochondritis dissecans results from a loss of the blood supply to an area ofbone underneath a joint surface and usually involves the knee. The affected boneand its covering of cartilage gradually loosen and cause pain. This problemusually arises spontaneously in an active adolescent or young adult.The involvement of several joints or the appearance ofosteochondritis dissecans in several family members may indicate that thedisorder is inherited.Symptoms and DiagnosisIf normal healing doesn't occur, cartilage separates from the diseased bone and afragment breaks loose into the knee joint, causing weakness, sharp pain, andlocking of the joint. An x ray, MRI, or arthroscopy can determine the condition of the cartilage and can be used to diagnose osteochondritis dissecans.What Is Plica Syndrome?Plica (PLI-kah) syndrome occurs when plicae (bands of synovial tissue) areirritated by overuse or injury.Symptoms and DiagnosisPeople with this syndrome are likely to experience pain and swelling, a clickingsensation, and locking and weakness of the knee. Because the symptoms aresimilar to those of some other knee problems, plica syndrome is oftenmisdiagnosed.How Can People Prevent Knee Problems?Some knee problems, such as those resulting from an accident, can't be foreseen or prevented. However, a person can prevent many knee problems by following these suggestions:Before exercising or participating in sports, warm up by walking or riding a stationary bicycle, then do stretches. Stretching the muscles in the front of the thigh (quadriceps) and back of the thigh (hamstrings) reduces tension on the tendons and relieves pressure on the knee during activity.Strengthen the leg muscles by doing specific exercises (for example, by walking up stairs or hills, or by riding a stationary bicycle). A supervised workout with weights is another way to strengthen the leg muscles that support the knee.Avoid sudden changes in the intensity of exercise. Increase the force or duration of activity gradually.Wear shoes that both fit properly and are in good condition to help maintain balance and leg alignment when walking or running. Knee problems can be caused by flat feet or overpronated feet (feet that roll inward). Maintain a healthy weight to reduce stress on the knee. Obesity increases the risk of degenerative (wearing) conditions such as osteoarthritis of the knee.What Types of Exercise Are Most Suitable for Someone WithKnee Problems?Three types of exercise are best for people with arthritis:Range-of-motion exercises help maintain normal joint movement and relieve stiffness. This type of exercise helps maintain or increase flexibility.Strengthening exercises help keep or increase muscle strength. Strong muscles help support and protect joints affected by arthritis.Aerobic or endurance exercises improve function of the heart and circulation and help control weight. Weight control can be important to people who have arthritis because extra weight puts pressure on many joints. Some studies show that aerobic exercise can reduce inflammation in some jointsSignificant History• Onset, history and location of pain• Previous history of similar problems in knee or other joints• Response to activity• Factors that aggravate pain• Factors that relieve pain• Presence and location of swelling• Stiffness• Grinding, catching, locking or snapping• Fever or chills• Change in sensation or muscle strengthPhysical Examination:As well as taking an accurate history, it is important to carry-out a comprehensive physical assessment. This involves testing every structure in the knee- even if you have a good idea what the injury is. Depending on the mode of injury, it is not uncommon for more than one structure to be damaged.1. Observation:Observe the patient in standing, walking and lying. Note ability to weight bear during mobilization and amount of swelling present in the knee. Listen for audible cracks or clicks.2. Active Movements:Ask the patient to actively move the injured knee through flexion and extension. Compare range of motion to the uninjured knee and note any added pain on movement.Ask the patient to perform a straight leg raise in lying. This gives a good indication of muscle strength.3. Passive Movements:The patient relaxes the muscles in the injured leg allowing the therapist to passively flex and extend the knee through the available range.Watch for signs of "muscle guarding" (muscle contraction brought on by pain to prevent further movement of the limb), audible clicks and quality of movement e.g. stiffness or a soft "end-feel" at the end of range.4.Palpation:Only after seeing the available movement in the knee should the area be palpated. The following sites should be palpated:The joint lines both medial and lateral sides- pain may indicate an MCL or LCL injuryPatellofemoral joint- patellar tendon and quadriceps tendonPatella- move the patella in all directionsPosterior joint- look for signs of Bakers cyst and palpate the muscle tendons of the gastrocnemius and hamstrings.5. Special Tests:A number of special tests exist to investigate the individual structures of the knee. These includeA. Ligament Stability Tests:Anterior cruciate ligament - Lachmans and anterior drawer (video).Posterior cruciate ligament - stressing the ligament (video).LCL- pressure on medial aspect of knee when in 30 degreesMedial ligament - pressure on lateral side of knee joint when in 30 degrees of flexion (video).B. Meniscal Tests:Medial Meniscus- McMurrays.Lateral Meniscus- McMurrays.Rotating and pressing down on the knee in prone position (video).C. Patella:Assess the 'tracking" movement of the patella both medial and laterally. This is particularly important in cases where a patellar dislocation has been suspected.Scoop test for swelling on the knee (video).Glide test for pain under the patella (video).Differential diagnosis by LOCATION:• Anterior - Patellofemoral syndrome, bursitis, Osgood-Schlatter’s disease, patellar tendinitis, patellar fracture• Medial - meniscus, MCL, DJD, pes anserine bursitis• Lateral - Meniscus, LCL, DJD, iliotibial band friction syndrome, fibular head dysfunction• Posterior - hamstring injury, tear of posterior horn of medial or lateral meniscus, Baker’s cyst, neurovascular injury (popliteal artery or nerve)*CONTACT INJURIES/DIRECT BLOWS:• Commonly cause injury to: collateral ligaments, patellar dislocation, epiphyseal fractures in children with open growth plates• Valgus