The knee examination, in

medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pract ...

and

physiotherapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions. It is provided by physical therapists who promote, maintain, or restore health through physical examination, diagnosis, management, prognosis, patient ...

, is performed as part of a

physical examination In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the patien ...

, or when a patient presents with

knee In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the hu ...

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

or a history that suggests a

pathology Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in ...

of the

knee joint In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the hu ...

. The exam includes several parts: *position/lighting/draping *inspection *palpation *motion The latter three steps are often remembered with the saying ''look, feel, move''.

History taking

Before performing a physical examination of the knee joint, a comprehensive history should be asked. A thorough history can be helpful in locating the possible pathological site during the physical examination. The mechanism of injury, location, character of the knee pain, the presence of a "pop" sound at the time of the injury (indicates ligamentous tear or fracture), swelling, infections, ability to stand or walk, sensation of instability (suggestive of

subluxation A subluxation is an incomplete or partial dislocation of a joint or organ. According to the World Health Organization (WHO), a subluxation is a "significant structural displacement", and is therefore always visible on static imaging studies, suc ...

), or any previous traumatic injuries to the joint are all important historical features. The most common knee problems are: soft tissue inflammation, injury, or

osteoarthritis Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the w ...

. The mechanism of the knee injury can give a clue of the possible structures that can be injured. For example, applying

valgus stress The valgus stress test or medial stress test is a test for damage to the medial collateral ligament of the knee. It involves placing the leg into extension, with one hand placed as a pivot Pivot may refer to: *Pivot, the point of rotation in a ...

on the knee can cause

medial collateral ligament The medial collateral ligament (MCL), or tibial collateral ligament (TCL), is one of the four major ligaments of the knee. It is on the medial (inner) side of the knee joint in humans and other primates. Its primary function is to resist out ...

rupture, meanwhile a varus force can cause lateral collateral ligament rupture. When a person suddenly slows down during running, twisting, or pivoting with valgus force applying on the knee, the

anterior cruciate ligament The anterior cruciate ligament (ACL) is one of a pair of cruciate ligaments (the other being the posterior cruciate ligament) in the human knee. The two ligaments are also called "cruciform" ligaments, as they are arranged in a crossed formation ...

can rupture. Posterior dislocation of the tibia can cause

posterior cruciate ligament The posterior cruciate ligament (PCL) is a ligament in each knee of humans and various other animals. It works as a counterpart to the anterior cruciate ligament (ACL). It connects the posterior intercondylar area of the tibia to the medial cond ...

injury. Twisting and pivoting while bearing weight can cause tearing of the

meniscus Meniscus may refer to: *Meniscus (anatomy), crescent-shaped fibrocartilaginous structure that partly divides a joint cavity *Meniscus (liquid) The meniscus (plural: ''menisci'', from the Greek for "crescent") is the curve in the upper surface ...

. Fractures of the knee are less common but should be considered if direct trauma to the knee has occurred such as during a fall. Examples of fractures involving knee joints are:

tibial plateau fracture A tibial plateau fracture is a break of the upper part of the tibia (shinbone) that involves the knee joint. Symptoms include pain, swelling, and a decreased ability to move the knee. People are generally unable to walk. Complication may include ...

s, fractures of the

lateral condyle of femur The lateral condyle is one of the two projections on the lower extremity of the femur. The other one is the medial condyle. The lateral condyle is the more prominent and is broader both in its front-to-back and transverse diameters. Clinical sign ...

medial condyle of femur The medial condyle is one of the two projections on the lower extremity of femur, the other being the lateral condyle. The medial condyle is larger than the lateral (outer) condyle due to more weight bearing caused by the centre of mass being med ...

, and

patellar fracture A patella fracture is a break of the kneecap. Symptoms include pain, swelling, and bruising to the front of the knee. A person may also be unable to walk. Complications may include injury to the tibia, femur, or knee ligaments. It typically res ...

s. For non-traumatic causes of knee pain, history such as fever, morning stiffness, pain after exercise, infections, history of

gout Gout ( ) is a form of inflammatory arthritis characterized by recurrent attacks of a red, tender, hot and swollen joint, caused by deposition of monosodium urate monohydrate crystals. Pain typically comes on rapidly, reaching maximal intensit ...

psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small, localized patches to complete ...

, and previous activities that contributes to long-term overuse of the knee joint should be asked. Knee pain due to long-term overuse are reproducible. For example, repetitive jumping can cause inflammation of patellar tendon. Repetitive kneeling can cause prepatellar inflammation of

synovial bursa Synovial () may refer to: * Synovial fluid * Synovial joint * Synovial membrane * Synovial bursa Synovial () may refer to: * Synovial fluid * Synovial joint * Synovial membrane The synovial membrane (also known as the synovial stratum, synovi ...

General examination

Physical examination of the knee begins by observing the person's

gait Gait is the pattern of movement of the limbs of animals, including humans, during locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on speed, terrain, the need to maneuver, and energetic efficiency. Di ...

to assess for any abnormalities seen while walking. Gait assessment can be used to differentiate genuine knee pain or pain which referred from hip, lower back or the foot. A person can be asked to perform a

duckwalk The duckwalk is a form of locomotion performed by assuming a low squatting position#Stalking.2C prowling and duckwalking, partial squatting position and walking forwards, maintaining the low stance. It is similar to stalking and prowling. It is m ...

. This requires the person to squat and walk in that position. In order to perform a duckwalk, the person has to be free of ligamentous tear, knee effusions, and meniscal tears. The person can also be asked to stand with both feet stuck together. This position is useful to observe for valgus or varus deformity of the knees which is suggestive of

. The circumference of each thigh can be measured to look for wasting of quadriceps muscles. Skin around the knee can also be observed for psoriasis, hematoma,

rash A rash is a change of the human skin which affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cr ...

, abrasions, lacerations, or

cellulitis Cellulitis is usually a bacterial infection involving the inner layers of the skin. It specifically affects the dermis and subcutaneous fat. Signs and symptoms include an area of redness which increases in size over a few days. The borders of t ...

which could be important causes of the knee pathology.

Palpation

Palpation of the knee should begin from the unaffected side first. This will reassure the patient and is useful for comparison with the affected knee. The back of the hand can be used to assess the warmth of the knee. The knee is then flexed 90 degrees and the anterior structures are assessed. Inflammation of the patellar tendon is present if the patellar tendon is painful upon palpation. Radiographic imaging should be done if the examination findings fulfills the Ottawa rules: age 55 years and older, pain at the

head of fibula The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity is ...

, patellar pain, unable to flex the knee to 90 degrees, and inability to stand and walk at least four steps. If

injury is suspected, radiographic imaging should also be ordered because it is frequently associated with lateral

. If there is a painful, reddish, and warm swelling in front of the patella, acute

prepatellar bursitis Prepatellar bursitis is an inflammation of the prepatellar bursa at the front of the knee. It is marked by swelling at the knee, which can be tender to the touch and which generally does not restrict the knee's range of motion. It can be extreme ...

should be considered which may require aspiration or drainage. Those presented with these features usually had history of frequent kneeling and direct trauma over the knee. Pain, swelling, and a defect of the insertion of the quadriceps tendon into the superior part of the patella is suggestive of quadriceps tendon rupture. A "pop" sound may be associated with this injury, followed by the loss of the ability to straighten the knee (knee extension). Pain at the medial joint line (medial to the inferior border of the patella) indicates medial compartment osteoarthritis, injury to the medial collateral ligament, or a medial meniscal tear. Pain at the midpoint between the anterior part of the medial joint line and

tibial tuberosity The tuberosity of the tibia or tibial tuberosity or tibial tubercle is an elevation on the proximal, anterior aspect of the tibia, just below where the anterior surfaces of the lateral and medial tibial condyles end. Structure The tuberosity o ...

is suggestive of

Pes anserine bursitis Pes anserine bursitis is an inflammatory condition of the medial (inner) knee at the anserine bursa, a sub muscular bursa, just below the pes anserinus. Pathology The pes anserinus is where the tendons of the sartorius, gracilis, and semiten ...

(inflammation of

anserine bursa The anserine bursa (tibial intertendinous bursa) is a sub muscular bursa located deep to the pes anserinus on the anteromedial proximal tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (fr ...

. Lateral joint line tenderness is associated with lateral compartment osteoarthritis, lateral collateral ligament injury, and lateral meniscal tear. Pain at the

lateral femoral condyle The lateral condyle is one of the two projections on the lower extremity of the femur. The other one is the medial condyle. The lateral condyle is the more prominent and is broader both in its front-to-back and transverse diameters. Clinical sign ...

is suggestive of

iliotibial band syndrome Iliotibial band syndrome (ITBS) is the second most common knee injury, and is caused by inflammation located on the lateral aspect of the knee due to friction between the iliotibial band and the lateral epicondyle of the femur. Pain is felt most ...

. Swelling at the

popliteal fossa The popliteal fossa (also referred to as hough, .html" ;"title="/sup>">/sup> or kneepit in analogy to the cubital fossa) is a shallow depression located at the back of the knee joint. The bones of the popliteal fossa are the femur and the tibia ...

may reveal a

Baker's cyst A Baker's cyst, also known as a popliteal cyst, is a type of fluid collection behind the knee. Often there are no symptoms. If symptoms do occur these may include swelling and pain behind the knee, or knee stiffness. If the cyst breaks open, pain ...

Motion

Assessment of effusion

The absence of normal grooves around patella may indicates a patellar intra-articular effusion. There are two ways to confirm the effusion. The knee is extended fully before the examination begins. This first way is the patellar tap. It is to squeeze the fluid between the patella and the femur by pressing at the medial patella using a non-dominant hand. Then, using the dominant hand to press on the patella vertically. If the patella is ballotable, then patellar intra-articular effusion is present. Another way is the milking of the patella. First, the effusion is milked at the medial border of the patella from inferior to superior aspect. Then, using another hand, the effusion is milked at the lateral border of the patella from superior to inferior aspect. If effusion is present, a bulge will be appear at the medial border of the patella because the effusion is milked back to the medial patella.

Assessment of range of motion

Both the active and passive range of motion should be assessed. The normal knee extension is between 0 and 10 degrees. The normal knee flexion is between 130 and 150 degrees. Any pain, abnormal movement, or crepitus of the patella should be noted. If there is pain or crepitus during active extension of the knee, while the patella is being compressed against the patellofemoral groove,

patellofemoral pain syndrome Patellofemoral pain syndrome (PFPS; not to be confused with jumper's knee) is knee pain as a result of problems between the kneecap and the femur. The pain is generally in the front of the knee and comes on gradually. Pain may worsen with sittin ...

chondromalacia patellae Chondromalacia patellae (also known as CMP) is an inflammation of the underside of the patella and softening of the cartilage. The cartilage under the kneecap is a natural shock absorber, and overuse, injury, and many other factors can cause inc ...

should be suspected. Pain with active range of motion but no pain during passive range of motion is suggestive of inflammation of the tendon. Pain during active and passive range of motion is suggestive of pathology in the knee joint.

Assessment of collateral ligaments

Valgus stress test can be performed with the examined knee in 25 degrees flexion to determine the integrity of the medial collateral ligament. Similarly, varus stress test can be performed to access the integrity of the lateral collateral ligament. The degree of collateral ligament sprain can also be assessed during the valgus and varus tests. In a first degree tear, the ligament has less than 5 mm laxity with a definite resistance when the knee is pulled. In a second degree sprain, there is laxity when the knee is tested at 25 degrees of flexion, but no laxity at extension with a definite resistance when the knee is pulled. In a third degree tear, there will be 10 mm laxity with no definite resistance either with knee with full extension or flexion.

Assessment of anterior cruciate ligament

The anterior drawer and

Lachman test The Lachman test is a clinical test used to diagnose injury of the anterior cruciate ligament (ACL). It is recognized as reliable, sensitive, and usually superior to the anterior drawer test. Description The knee is flexed at 15 degrees with the ...

s can be used to access the integrity of the anterior cruciate ligament. In the anterior drawer test, the person being examined should lie down on their back (supine position) with the knee in 90 degrees flexion. The foot is secured on the bed with the examiner sitting on the foot. The tibia is then pulled forward by using both hands. If the anterior movement of the affected knee is greater than the unaffected knee, then the anterior drawer test is positive. The Lachman test is more sensitive than the anterior drawer test. For the Lachman test, the person lies down in supine position with the knee flexed at 20 degrees and the heel touching the bed. The tibia is then pulled forward. If there is 6 to 8 millimeters of laxity, with no definitive resistance when the knee is pulled, then the test is positive thus raising concern for a torn anterior cruciate ligament. A large collection of blood in the knee can be associated with bony fractures and cruciate ligament tear.

Assessment of posterior cruciate ligament

Posterior drawer test and tibial sag tests can determine the integrity of the posterior cruciate ligament. Similar to anterior drawer test, the knee should be flexed 90 degrees and the tibia is pushed backwards. If the tibia can be pushed posteriorly, then the posterior drawer test is positive. In tibial sag test, both knees are flexed at 90 degrees with the person in supine position and bilateral feet touching the bed. Bilateral knees are then watch for posterior displacement of tibia. If the affected tibia slowly displaced posteriorly, the posterior cruciate ligament is affected.

Assessment of meniscus

Those with meniscal injuries may report symptoms such as clicking, catching, or locking of knees. Apart from joint line tenderness, there are three other methods of accessing meniscus tear: the

McMurray test The McMurray test, also known as the McMurray circumduction test is used to evaluate individuals for tears in the meniscus of the knee. A tear in the meniscus may cause a pedunculated tag of the meniscus which may become jammed between the joint sur ...

, the Thessaly test, and the

Apley grind test The Apley grind test or Apley test is used to evaluate individuals for problems in the meniscus of the knee. The Apley grind test has a reported sensitivity of 97% and a specificity of 87%. Description In order to perform the test, the patient lies ...

. In McMurray test, the person should lie down in supine position with the knee should in 90 degrees flexion. the examiner put one hand with the thumb and the index finger on the medial and lateral joint lines respectively. Another hand is used to control the heel. To test the medial meniscus, the hand at the heel applies a valgus force and external rotates the leg while extending the knee. To test for the lateral meniscus, the varus force, internal rotation are applied to the leg while extending the knee. Any clicking, popping, or catching at the respective joint line indicates the corresponding meniscal tear. In Apley compression test, the person lie down in

prone Prone position () is a body position in which the person lies flat with the chest down and the back up. In anatomical terms of location, the dorsal side is up, and the ventral side is down. The supine position is the 180° contrast. Etymolog ...

position with the knee flexed at 90 degrees. One hand is used to stabilise the hip and another hand grasp the foot and apply a downward compression force while external and internal rotates the leg. Pain during compression indicates meniscal tear. Examination for anterior cruciate ligament tear should be done for those with meniscal tear because these two conditions often occurs together.

Additional Tests

Clarke's test In medicine, Clarke's test (also known as the Osmond-Clarke test or patellar grind test) is a component of knee examination which may be used to test for patellofemoral pain syndrome, chondromalacia patellae, patellofemoral arthritis, or ante ...

may be used to examine for patello-femoral pain *The ''Wilson test'' is a test used to detect the presence of

osteochondritis dissecans Osteochondritis dissecans (OCD or OD) is a joint disorder primarily of the subchondral bone in which cracks form in the articular cartilage and the underlying subchondral bone. OCD usually causes pain during and after sports. In later stages ...

in the knee.

References

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