Assessment of the knee joint



Knee Joint

Anatomy:

Introduction:

• The knee joint is the largest, most complex, and probably the most vulnerable joint in the body, it is medically known as the tibiofemoral joint.

• This joint is a complex hinge joint and in addition to flexion and extension permits limited rolling, gliding, and rotational movement.

• This joint is dependent on the muscles and ligaments which surround it for strength.

Joint structures:

1. Bones :( fig.1):

• The knee is made up of four bones. The femur superiorly (on two rounded surfaces called condyles), which is the large bone in the thigh, attaches by ligaments and a capsule to the tibia (or the shinbone) inferiorly. Just below and next to the tibia is the fibula, which runs parallel to the tibia. The patella or what we call 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.

• N.B:

On the outer aspects of both condyles are the epicondyles, which serve as sites for muscle and ligament attachment. In the space between the condyles is a depression called the intracondylar fossa, which is the site of attachment of the cruciate ligaments.

Fig.1: Bones of the knee joint

2. Muscles:

• The knee muscles which go across the knee joint are the quadriceps and the hamstrings. The quadriceps muscles are on the front of the knee (extend the knee), and the hamstrings are on the back of the knee (flex the knee).

3. Ligaments: (fig.2):

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

a) Medial collateral ligament:

• The medial collateral ligament is located at the inner aspect of the knee joint; it extends from the medial femoral epicondyle to the tibia.

• This ligament prevents excessive abduction of the knee.

b) Lateral collateral ligament:

• The lateral collateral ligament is located at the outer aspect of the knee joint; it extends from the lateral femoral epicondyle to the head of the fibula.

• This ligament prevents excessive adduction of the knee.

c) Anterior cruciate liagement: ( fig.3):

• Anterior cruciate ligament is located in the center of the knee joint; it extends posterolaterally from the tibia and inserts on the lateral femoral condyle.

• This ligament prevents the femur from sliding backwards on the tibia (or the tibia sliding forwards on the femur).

d) Posterior cruciate ligament:

• Posterior cruciate ligament is also located in the center of the knee joint it extends anteromedially from the tibia posterior to the medial femoral condyle.

• This ligament prevents the femur from sliding forward on the tibia (or the tibia from sliding backwards on the femur).

N.B:

• Both of these ligaments stabilize the knee in a rotational fashion. Thus, if one of these ligaments is significantly damaged, the knee will be unstable when planting the foot of the injured extremity and pivoting, causing the knee to buckle and give way. The abnormal motion causes damage to the surface on the underside of the patella.

• They are called cruciate ligaments because the ACL "crosses" in front of the PCL.

[pic]

Fig.2: Ligaments of the knee joint

[pic]

Fig.3: Cruciate ligaments

4. Cartilage:

a) Meniscus:

• The knee joint has a structure made of cartilage, which is called the meniscus or meniscal cartilage. The meniscus is a C-shaped piece of tissue which fits into the joint between the tibia and the femur; there is a medial meniscus and a lateral meniscus.

• These structures act as "cushions" or "shock absorbers".

• They also help provide stability to the knee.

• It helps to protect the joint and allows the bones to slide freely on each other.

N.B:

When either meniscus is damaged, it is often referred to as a "torn cartilage".

b) Articular cartilage:

• 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.

5. Tendons:

• Tendons connect muscles to bone. 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.

6. Bursae:

• 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.

• A bursa is a small fluid filled sac that decreases the friction between two tissues.

• Bursae also protect bony structures.

• Normally, a bursa has very little fluid in it but if it becomes irritated it can fill with fluid and become very large.

N.B

• In review, the bones support the knee and provide the rigid structure of the joint, the muscles move the joint, and the ligaments stabilize the joint.

• To function well, a person needs to have strong and flexible muscles. In addition, the meniscal cartilage, articular cartilage and ligaments must be smooth and strong. Problems occur when any of these parts of the knee joint are damaged or irritated.

Osteoarthritis:

Osteoarthritis is the commonest joint disorder. It is strongly associated with ageing and is a major cause of pain and disability in the elderly population. It was considered to be an exclusively degenerative disorder that was a result of wear and tear in elderly joints. More recent work, however, suggests that this is not the cause and that the pathological processes in OA are more dynamic in nature. It is not a single disease process but rather the outcome of a range of processes and disorders that can eventually lead to structural and functional failure of one or more synovial joints

The disease is characterized by focal destruction of cartilage and remolding of subchondral bone, in addition the joint capsule and synovial membrane as well as the ligaments, muscles and tendons surrounding the diseased joint are susceptible to varying degrees of degenerative changes. For initiation of O.A damage to the articular cartilage and the underlying bone structures, above some threshold value is required; below this threshold value the body’s natural repaire mechanism can prevent progressive damage to the articular cartilage

Pathology of Osteoarthritis

O.A could be primary or secondary. Primary osteoarthritis is considered to be a part of the aging processes especially in obese subjects, there is no obvious cause, it is due to an intrinsic alteration of the articular tissues themselves, it affects joints in a classical pattern and is common in postmenopausal women, in whom there is generalized nodal osteoarthritis, white women are most often affected during fifth and sixth decades, by polyarticular involvement of many joints the onset can be relatively sudden, with hot, inflamed distal interphalangeal joints

In secondary osteoarthritis repeated minor trauma may lead to micro fractures and subsequent O.A, occupational factors are though to be important in the development of secondary O.A, joint infection puts a joint at risk of O.A, as does deformity, for example following fractures which cause biomechanical anomalies or direct cartilage damage if the fracture included the articular surface. Overweight is linked to the development of O.A in some joints but not in others, there is a correlation between high body mass index and knee osteoarthritis which may be due to varus deformities, in obese persons being overweight may result in premature muscle fatigue which in turns leads to abnormal kinematics and subsequent development of O.A, the relationship seems to be much stronger in women, increased load across the joints clearly plays a role but hormonal abnormalities associated with obesity may be also be to blame

lame .

As regard to bones and joints, if the joint is rested the wear particles are gradually absorbed, fibrous tissue may form in the defect on the joint surface but as time goes by, this repair process gradually fails and the articular surface is eroded to exposes subchondral bone, which subsequently becomes polished and eburanted, row bone rubbing against raw bone is painful, the eburanted bone is not as slippery as healthy articular cartilage, friction across the joint is increased and weight transmisstion across the joint becomes uneven, these changes overloads parts of the joint surface and microfractures occur in the trabecula of the cancellous bone, the microfactures heel with callus, which increase the rigidity of the bone so that the bone gradually becomes denser, more sclerotic and less resilience this in turn, causes more microfractures and the normal architecture of the bone is Lost.

Effect of O.A on articular cartilage occurring through fibrillation, or minute cracks and loss of water content occur which lead to softening, splitting and fragmentation of cartilage, this occurs in both weight bearing and non weight bearing areas of the joint surfaces, collagen fibers split and there is disorganization of the normal proteoglycan collagen .

Limited cartilage repair can occur. Superficial lesions of articular cartilage show little healing but deep lesions that penetrate cortical bone allow the influx of marrow cells and the formation of fibro cartilage the subchondral bone is also abnormally active, with an increase in both the density of the tissue and the number of cells. At the margin of the joint new bone forms as osteophytes covered by fibrocartilage, the osteophytes restrict joint movement, a line of dense, hard, resilience bone forms just below the cartilage and the joint “remodel” so that there is a change in shape and congruity.

As the disease advance the joint becomes progressively stiffer and more deformed as the osteophytes enlarge and the bone surfaces are worn away, as bone is lost the ligaments become looser not because they lengthen but because the bone that they support become shorter .

The irritation of the synovium is probably due to the release of intracellular enzymes, including lysosymes, which produce hyperaemia and a cellular response in the sensorial layers, the synovium can also produce degradative enzymes and mediators such as interleukin-1, which may influence chondrocyte activity, other potential causes of damage included, free radicals and the deposition of immune complex.

The primary complaint of patients suffering from O.A is pain which result from irritation of sensory nerve endings in the synovium from osteophytes, periarticular muscle spasm and bone angina from diminished blood flow and elevated intraosseous pressure, synovial inflammation with associated release of prostaglandins, leukotrienes and various cytokines can also causes pain.

Assessment of the knee joint

1-Radiological Examination:

✓ Plain X-ray Radiography

[pic]

Fig. (5)

✓ CT and MRI



✓ Arthroscopy

It is examining the joint with a tiny camera (arthroscopy). During arthroscopy, small incisions are made around the joint and a tiny camera is inserted to see inside the joint.

Fig. (6)

✓ Radionuclide bone scan

It is a nuclear imaging technique that uses a very small amount of radioactive material, which is injected into the patient's bloodstream to be detected by a scanner. This test shows blood flow to the bone and cell activity within the bone.

➢ Determine the Q-angle (by X ray) by measuring the angle between the tibia and femur to exclude the prescence of patellofemoral pain

[pic]

Fig. (7)

COMPREHENSIVE EXAMINATION

1-ROM Measurement:

Through the years many devices have been designed and used to measure joint motion. The best known device is the goniometer is a device containing a 180 degree protractor for measuring the angle of a joint; it is used in tests of flexibility. Some goniometers can only measure the angle of a static joint, but an electrogoniometer can record continuously the changes in the angle of a joint during movements.

• 2-D measurement of ROM:

1-the universal goniometer

The simplest of all these devices, the universal goniometer remains the instrument most commonly used clinically. The two arm goniometer is still the most widely used, most often studied, most economical and most portable device for evaluation of ROM. However these devices have limitations, the starting position must be assessed visually, additionally, the conventional goniometer must be held with two hands leaving neither handfree for stabilization of the body on the proximal part of the joint. The center of rotation , the long axis of the limb, and the true vertical and horizontal position can also be only visually estimated, leading to incorrect measurements with limited repeatability. To address some of these problems, goniometres of various shapes and sizes have been developed to facilitate application and stabilization according to differences in contour between large and small joints. goniometer is also inadequate for measurement of other complex motions, such as supination, pronation, elevation and inversion.

[pic] [pic][pic]

Fig. (8) Universal goniometer

2- Visual estimation

The practice of visual estimation had been described by several authors. it is obviously the easiest technique to use ,since no equipment is need and it is practical when no equipment in hand. researchers suggested that measurement with instrument produced more reliable results than the visual estimation, however when observing rapid motion at more than one joint details escape even with the most experienced observer.

3-Electrogoniometers are electronic versions of the standard goniometers used in the clinic to measure joint range of motion or angular displacement. It converts the angular motion into an electrical signals.Available in unixial and biaxial form, the electrogoniometer consists of one or two potentiometers or strain gauges between two bars. Placed across the joint to be measured, the potentiometer produces a varying voltage output depending on the angle of motion. Some electrogoniometers have three potentiometers so that they can measure motion in all 3 cardinal planes. To ensure maximum accuracy the position of the potentiometer is adjusted so that it is as close to the joint axis as possible. The main advantage of electrogoniometers is that they measure dynamic joint motion and play major role in more sophisticated gait analysis. It may be utilized in the analysis of athletic performances and industrial tasks, the appraisal of prosthetic devices and the achievement levels of disabled individuals, the evaluation of the effect of the therapeutic modalities on the ROM, and the study of motion and locomotion of in animals. It used in quantification of specific joint motion outside the lab (e.g. on the worksite for ergonomic analysis,

Also advantages of electrogoniometry include ease of set up and processing, relatively low cost, and, with small data loggers, portability for collection in the workplace or other sites. These data loggers permit the collection and storage of large quantities of data over a prolonged period such as a workday Disadvantages include the lack of data with respect to the global reference system, errors due to alignment of the axes of rotation, difficulty in monitoring joints surrounded by large amounts of soft tissue (such as the hip), and cross talk between potentiometers, furthermore, as the output from the electrogoniometer is the relative angle between the two arms, when used in a patient with a fixed flexion deformity it may be difficult to decide which angle is taken as zero.

[pic]

Fig. (9)electrogoniometer

3. Electromagnetic systems: are based on low-frequency magnetic coils that permit real time 6-DOF tracking of segments by sensors placed on the segments. Limitations include cabling to connect sensors that can inhibit movement, slippage of the sensors, number of sensors that can be tracked at one time (usually up to four), and cost. Interference from metallic objects or other magnetic fields will degrade performance. Benefits include the elimination of marker dropout from the camera field of view (which can occur in videography), real time 6-DOF data, and accuracy.

• 3. D measurement system

4. Imaging systems are divided into cinematography, optoelectronics, and videography systems.

 

4.1 Cinematography, the earliest imaging system developed, provides a high quality image, but lacks automated systems for data reduction. Therefore, it is costly and time consuming.

 

4.2 Optoelectronic systems: employ active markers that are usually light emitting (infrared) diodes (LED’s) placed on the segments or joints. The LED’s are triggered and pulsed sequentially by a computer, permitting automatic identification of each marker. Advantages include automated marker tracking hence no marker merging or misidentification. However, optoelectronic systems require wire connection to the LED’s, which makes measurement cumbersome and limits them to the laboratory environment. More than one unit may be required to obtain adequate marker coverage.

 

[pic]

Fig.(10)

4.3 Videography is the most frequently used type of motion analysis. These systems use one or more cameras to track passive reflective markers, which do not require wires. Passive markers reflect either external ambient light or camera-projected light (frequently infrared). The markers then reflect the light back into the camera lens, and the digital signal is fed into a computer. A threshold is set to automatically discriminate the marker “pixels” which are the brightest objects in the laboratory. Because all markers are visible at any given time, potential merging of markers in various camera views places limitations on how close together markers may be placed with these systems (generally limited to 2mm). When markers are lost from view or their trajectories cross, they can lose their proper identification. If a marker is occluded, some systems supply the missing point by interpolation. Cameras may have either analog or digital output. Benefits include the ability to track large numbers of markers, faster cameras (50-250Hz), and the potential for high precision and accuracy.

Video systems keep track of the horizontal and vertical coordinates of each marker from each camera. If only one camera is used (2-D), the assumption is that all motion is occurring in a plane perpendicular to the camera axis. This is seldom the case and any marker movement outside this plane will be distorted. As a result, 2-D systems are less accurate than 3-D systems, even if the researcher is only interested in one plane of motion. In 3-D systems, the computer software computes 3-D coordinates for each marker based upon the principle of optical triangulation. This includes the 2-D data from two or more cameras and the known location of all cameras. In practice, more than two cameras are necessary, as markers become obscured from camera views because of arm swings, subject rotation, or laboratory configuration. Many systems now employ 5 to 24 cameras.

Position of markers:

• Greater trochanter

• Knee joint line

• Lateral malleolus

2-Testing knee proproception

Proprioception : the ability to sense joint position and joint motion and is assessed by the isokinetic dynamometer by the repositioning accuracy.

• The patient is asked to sit on the chair of the biodex with his tested knee positioned in 90 degree flexion"starting position" and is stabilized by straps and is blind folded.

• Prior to testing the patient performs 2 tests to be familiarized with the procedures.

• Initially the anatomical reference angle was set at 30 degree then the patient leg was returned to the starting position

• For standardization, the tested limb was allowed to move to the target angle "30" actively by the patient then was held for 10 seconds as a teaching process and then the limb was allowed to return to the starting position by the apparatus.

• Then the patient was asked to move his limb to the target angle "30" actively, when the patient felt that he reached the target angle actively he told the examiner to stop the apparatus using Hold/Release button.

• Three trials are done with rest period of 3 minutes between the trials.

• The mean angular difference of the 3 trials between the target angle position and the patient perceived end range position will be recorded in degrees as the deficit in repositioning accuracy and will be used in the statistical analysis.

[pic]

Fig (11) testing knee proprioception

3-Flexibility Tests:

Ober’s test:

This test assesses the tensor fascia latae (iliotibial band) contracture.

The patient is in side lying position with the lower leg flexed at the hip and knee for stability.

The examiner stabilizes the pelvis by one hand and passively abducts and extends the patient upper leg with the knee straight or flexed to 90 with the other hand. The examiner then left the leg, if it remains abducted and doesn’t fall to the table so there is contracture of the muscle.

[pic]

Fig. (12)Ober’s test

Rectus femoris contracture test:

a- Kendall test:-

The patient lies supine with the knees bent over the edge of the examining table. The patient flexes non tested knee onto the chest and holds it. The angle of the tested knee should remain at 90 when the opposite knee is flexed. If the knee extended slightly, contracture is present. The two sides should be tested and compared.

[pic]

Fig. (13)

b- Hamstring contracture test:-

The patient is instructed to sit with one knee flexed against the chest to stabilize the pelvis and the other knee extended. The patient then attempts to touch the toes of the extended lower limb (the tested one) with the fingers. Normally, the patient should be able to touch the toes while the knee extended. If he is unable, it is indication of tight hamstring.

[pic]

Fig. (14)

4- Long and Round measurement

➢ Circumferential measurements: By tape measurement to determine atrophy of lower limb muscles (quadriceps, calf muscles), effusion around the knee joint.

➢ Long Measurement: Measure leg lengths from anterior superior iliac spine to medial malleolus by Tape measurement.

5- Pain assessment:

Pain Rating Scales

✓ Present Pain Intensity

[pic]

Fig. (15)

✓ Visual Analogue Scale

[pic]

Fig. (16)

6- Evaluation of Muscles Strength

✓ Isokinetic Dynamometer

Fig. (16)

Position of the subject:

The subject was attached in position after adjustment of depth of the seat, the height of the dynamometer and the length of the support lever that allowing the axis of rotation of the dynamometer to be aligned to the most inferior aspect of the lateral femoral epicondyle and lower leg was attached to the dynamometer lever arm above the medial malleolus by 2 inches. The subject was secured on the seat by wide strap placed diagonally on the subject chest. Thigh strap attached to the seat was used to stabilize the thigh.

The subject data were entered to the computer program data base, test protocol was set from the soft ware program; concentric unilateral protocol with extension of the knee range of motion was set (from 90 to 0), with angular velocity 60º per second.

The limb was weighed before testing by the biodex's automatic limb weighing system to correct for the gravitational effect on torque value. After checking the subject was ready, test procedure was started.

[pic]

Fig. (17)

Each subject was asked to hold into the sides of the chair with both hands during the testing procedures. The subject was instructed to maximally contract the dominant knee extensor muscle consistent verbal encouragement to ensure maximal effort. The subject was allowed to do two trials before actual test, and then was instructed to give maximum voluntary concentric torque via verbal command to kick as hard and fast as he/she can, then relax

7-TESTS FOR JOINT STABILTY

The knee joint owes its stability to a strong and extensive joint capsule, collateral ligaments, cruciate ligaments, and surrounding muscles and tendons. The following tests evaluate the strength and integrity of those structures.

Collateral Ligaments:

Ask the patient to lie supine on the table with one knee flexed just enough so that it unlocks from full extension. To test the medial collateral ligament, secure his ankle with one hand and place the other hand around the knee so that your thenar eminence is against the fibular head. Then, push medially against the knee and laterally against the ankle in an attempt to open the knee joint on the inside (valgus stress). Palpate the medial joint line for gapping, which may even be visible. If there is a gap, the medial collateral ligament is not supporting the knee properly. When stress on the injured joint is relieved, you can feel the tibia and femur "clunk" together as they close.

To test the lateral aspect of the knee for stability, reverse the position of your hands, and push laterally against the knee and medially against the ankle to open the knee joint on the lateral side (varus stress). Again, palpate the lateral joint line for any gapping. As on the medial side, such a gap may be both palpable and visible. Upon the release of varus stress, the tibia and femur may clunk into position as they close.

If your fingers are too short to reach around the knee to palpate the joint lines, secure the patient's foot between you arm and body (in the axilla) so that your hands are free to palpate the joint line. In this way, your body acts as a lever on the foot and applies varus and valgus stress to the knee joint.

Since the medial collateral ligament is critical to stability, an isolated tear of this ligament leads to joint instability, whereas a similar defect in the lateral collateral ligament may have little effect either way. Most ligamentous injures around the knee occur on the medial side.

Cruciate Ligaments:

The anterior and posterior cruciate ligaments are instrumental in preventing anterior and posterior dislocation of the tibia on the femur. These ligaments are intravascular, originating on the tibia and inserting into the inner sides of the femoral condyles.

To test the integrity of the anterior cruciate have the patient lie supine on the examination table with his knees flexed to 90" and his feet flat on the table. Position yourself on the edge of the table so that you can stabilize his foot by sitting on it.Then cup your hands around his knee,with your fingers on the area of insertion of the medial and lateral hamstrings and your thumbs on the medial and lateral joint lines,then draw the tibia forward,if it slides forward from under the femur, the ACL may be torn" positive anterior draw sign". A few degrees of anterior draw are normal if an equal amount is present on the opposite side. To test the PCL ,stay in the same position and push the tibia posteriorly, if it moves backward on the femur the PCL is probably damaged "positive posterior draw sign". The incidence of damage to the anterior cruciate is much higher than to the posterior cruciate. In fact, an isolated tear of the posterior cruciate ligament is rare.

These tests for stability of the anterior and posterior cruciate ligaments are usually performed in one continuous motion and have been separated here mainly for the purpose of instruction. All procedures should be performed bilaterally, and all findings compared.

McMURRAY TEST

During knee flexion and extension, a torn meniscus may produce a palpable or audible “clicking” in the region of the joint line. Tenderness elicited in palpation of the joint line on either side suggests the possibility of a torn meniscus. Posterior meniscal tears are difficult to identify, and the McMurray test was originally developed to assist in this difficult diagnosis.

Ask the patient to lie supine with his legs flat and in the neutral position. With one hand, take hold of his heel and flex his leg fully. Then, place your free hand on the knee joint with your fingers touching the medial joint line and your thumb and thenar eminence against the lateral joint line, and rotate the leg internally and externally to loosen the knee joint. Push on the lateral side to apply valgus stress to the medial side of the joint, while, at the same time, rotating the leg externally. Maintain the valgus stress and external rotation, and extend the leg slowly as you palpate the medial joint line. If this maneuver causes a palpable or audible “click” within the joint, there is a probable tear in the medial meniscus, most likely in its posterior half.

APLEY’S COMPRESSION AND DISTRACTION TESTS

Compression or Grinding Test: This is another procedure designed to aid in the diagnosis of a torn meniscus. Ask your patient to lie prone on the examining table with one leg flexed to 90ْ . Gently kneel on the back of his thigh to stabilize it while leaning hard on the heel to compress the medial and lateral menisci between the tibia and the femur. Then, rotate the tibia internally and externally on the femur as you maintain firm compression. It this maneuver elicits pain, there is probably meniscal damage. Ask your patient to describe the location of his pain as accurately as possible. Pain on the medial side indicates a damaged medial meniscus; pain on the lateral side suggests a lateral meniscal tear.

Distraction Test: The distraction test helps to distinguish between meniscal and ligamentous problems of the knee joint. This test should follow the compression test in logical progression. Remain in the same position described for the compression test, and maintain your stabilization of the posterior thigh. Apply traction to the leg while rotating the tibia internally and externally on the femur. This maneuver reduces pressure on the meniscus and puts strain upon the lateral and medial ligamentous structures. If the ligaments are damaged, the patient will complain of pain; if the meniscus alone is torn, the test should not be painful for him.

“BOUNCE HOME” TEST

This test is designed to evaluate a lack of full knee extension, most often secondary to a torn meniscus a loose body within the knee joint, often intravascular joint swelling. With the patient supine on the table, cup his heel in your palm and bend his knee into full flexion. Now, passively allow the knee to extend. The knee should extend completely, or “bounce home” into extension with a sharp end point. However, if the knee falls short, offering a rubbery resistance to further extension, there is probably a torn meniscus or some other blockage and bounce home motion cannot take place.

The most common knee problems are:

• Knee osteoarthritis.

• Injuries of the medial collateral ligament," sprain or complete tear".

• Injuries of the lateral collateral ligament," sprain or complete tear".

• Tear of the ACL." anterior draw sign".

• Tear of PCL." posterior draw sign".

• Torn meniscus. "McMURRAY test" and "compression or grinding test".

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Fig. (18) To test the medial collateral ligament, apply valgus stress to open the knee joint on the medial side.

Fig. (19) To test the lateral knee for stability, apply varus stress to open the knee joint on the lateral side.

Fig. (20) Position for eliciting the anterior draw sign.

Fig. (21) A positive anterior draw sign: Torn anterior cruciate ligament.

Fig. (22) A positive posterior draw sign: Torn posterior cruciate ligament.

Fig. (23) The McMurray test for meniscal tears. Flex the knee.

Fig. (24) With the knee flexed, internally and externally rotate the tibia on the femur.

Fig. (25) With the leg externally rotated, place a valgus stress on the knee.

Fig. (26) With the leg externally rotated and in valgus, slowly extend the knee, if click is palpable or audible, the test is considered positive for a torn medial meniscus, usually in the posterior postion.

Fig. (27) Apley's compression test for meniscal tears.

Fig. (28) Apley's distraction test for ligamentous damage.

Fig. (29) The "Bounce Home" test. Flex the knee.

Fig. (30)

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(Fig. 4): Osteoarthritis of the medial compartment of the knee joint. Adapted from (Dandy 2003, Pp. 200) .

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