Knee examination

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Introduction

  • Wash Your hands
  • Introduce yourself by name and role
  • Check the patient’s identity – name and Date of Birth
  • Explain the procedure – why you need to do it and what does it involve
  • Ask for consent
  • Expose the patient appropriately
  • Check if the patient is currently in any pain
How to Introduce Yourself

“Good morning, my name is .. and I am a medical student. Can I just check your name and date of birth?

-I have been asked to do an examination on your knee. This will involve me asking you to walk and then having a look, feel and moving the hip joint. Is that ok?

– For the purposes of this examination would you mind removing your trousers but keeping your underwear on?

– And before I start can I just check whether you are in any pain?”

Bedside Inspection

  • Observe the patient by standing at the end of the bed.
  • Comment on whether the patient is ABC:

A – Alert         B – (normal) Body habitus         C – Comfortable at rest

  • Observe the surroundings and comment of whether you can see any “paraphernalia of musculoskeletal disease”:

This is a description of the objects or items around a patient’s bedside that will give you an idea into the condition that they might have. It is important to highlight this to the examiner as this can give you many clues about the patient’s underlying diagnosis. Things to look for include:

  • Hands – the patient’s hands may indicate osteoarthritis or rheumatoid arthritis
  • Mobility aids/Zimmer frames, shoes (heel raises and supports) – gives an idea about the functional status of the patient.
  • Medication– any pain relief or steroids at the bedside?

 

Gait

Action: Ask the patient to walk to the end of the room, turn around and then walk back.

Assess for:

–> Smoothness: Is there any disruption to the normal gait cycle such as abnormalities in toe-off or heel strike?

–> Symmetry: Is the gait symmetrical on both sides? Asymmetry of the gait could be caused by problems such as leg-length discrepancy, fixed flexion deformity, or pain on one side which reduces full extension and weight bearing on that side.

–> Step Height: A damage to the common fibular nerve for example leads to a foot-drop on the affected side. This means the patient will not be able to dorsiflex which gives them a high step height to compensate.

Types of Gait

The gait cycle is made up of 6 phases.

  1. Heel-strike: this is when the heel first touches the floor.
  2. Foot flat: here the weight is transferred onto the leg as the foot is all in contact with the floor.
  3. Mid-stance: the weight is aligned and balanced on this leg.
  4. Heel-off: here the heel lifts off as you start to transfer weight onto the other leg.
  5. Toe-off: this is when the toes finally lift off the floor
  6. Swing: the foot swings forward until the heel comes back in contact with the ground restarting the cycle.

a) Antalgic gait – A type of gait where the stance phase is abnormally shortened to reduce time on that foot. It looks like a limp –> Implies pain in that leg

b) Waddling gait – this is due to weakness of the proximal muscles of pelvis which causes weakness of gluteus muscles. Patient moves upper body forwards and drags lower leg forward.

c) Spastic gait – this is described as a swinging gait where the patient swings his leg round as it is hyperextended. This is seen in UMN lesions such as stroke

d) High-stepping gait – this is due to damage of the deep branch of the common fibular nerve which leads to foot-drop due to loss of dorsiflexion. This means the patient has a high step in order to compensate.

e) Trendelenburg gait – this leads to dropping of the pelvis on the contralateral side when you are walking. It is due to damage to the gluteus medius on the supported side –> indicates a lesion of the superior gluteal nerve

f) Fixed flexion/hyperextended knee– the knee is in fixed flexion/knee is hyperextended- occurs in polio as patient have quadriceps wasting

Observation – Standing

Action: Ask the patient to stand upright with their arms by their side. Observe them from the front, side and back for any signs of musculoskeletal disease.

FROM THE FRONT:

Assess for:

–> Scars: These are indicators of any previous surgery, such as a an arthroscopy or a total knee replacement.

–> Swelling: This may indicate the presence of an effusions around the patella. 

–> Asymmetry/leg length discrepancy: Leg length discrepancy could be due to joint disease as a child, or a fixed flexion deformity of one of the limbs.

–> Varus/valgus deformity: Assess for  varus/valgus deformity of the knees. Osteoarthritis typically gives a varus deformity whereas rheumatoid gives a valgus deformity.

–> Quadriceps: Assess for any wasting of the quadriceps muscle bulk. This could be due to damage to the femoral nerve, but it also occurs after surgery due to inactivity and wasting of the quadriceps muscles.

 

Knee Effusion

Associated with an inflammatory process in the knee joint

Valgus Knee Deformity

Associated with rheumatoid arthritis

Varus Deformity

Associated with osteoarthritis

FROM THE SIDE:

Assess for:

–> Foot arches: Flattening of the feet or high arched feet are associated with condition. A high arch (pes cavus) is seen in Charcot-Marie-Tooth disease. Flat feet (pes planus) are risk factors for joint problems.

 

Pes Planus

Flattening of the foot arch

Pes Cavus

Associated with Charcot Marie Tooth Disease

FROM THE BACK:

Assess for:

–> Popliteal swelling: assess for swellings in the popliteal fossa that could be a popliteal aneurysm, Baker’s cyst or semimembranosus cysts 

–> Iliac crest: This should be level. Assess this for any pelvic tilt which may indicate weakness of the abductor muscles e.g. gluteus medius.

–> Hamstring bulk: Assess for wasting of the hamstrings (sarcopenia)

 

Popliteal fossa swelling

Differentials include Baker’s cyst and popliteal artery anuerysm

Observation- Lying

Action: Ask the patient to lay down on the couch with the seat reclined at 45 degrees. Tell them to keep their legs outstretched and relaxed so that you can inspect their legs.

Assess for:

–> Scars: Have a closer look for any scars indicative of previous knee surgery.

–> Muscles: Compare both sides looking for evidence of muscle wasting or fasciculations.

–> Abnormal positions: Look at the resting angle of the legs. Are they abducted, externally rotated or is there any evidence of limb shortening?

Total Knee Replacement Scar

Knee Arthroscopy Scars

Leg lengths

Action: Offer to measure the true and apparent leg length. In your exam, the examiner may give you a measuring tape so you can formally assess this:

Assess for:

–> Apparent leg length: This is measured from the umbilicus to the medial malleolus. A discrepancy in the apparent leg length is suggestive of a tilted pelvis, which makes the legs appear unequal in length. This is often due to spinal or pelvic problems e.g. scoliosis.

–> True leg length: This is measures from the ASIS to the ipsilateral medial malleolus. Unequal true leg lengths is more suggestive of an actual limb pathology which leads to shortening e.g. neck of femur fracture. 

 

Quadriceps Bulk

Action: Offer to measure the circumference of the thighs to assess whether there is any wasting of the quadriceps muscles. In order to do this, use a measuring tap to measure the circumference 20cm above the tibial tuberosity.

Assess for:

–> Quadriceps wasting: A discrepancy of >2cm is indicative of quadriceps wasting on one side.

 

Feel

Action: With the patient lying down, using the backs of your hands, palpate both the hip joints, seeing if you can find a temperature difference between the two legs.

Assess for:

–> Temperature: A raised temperature is indicative of an inflammatory process occurring. This could be due to an inflammatory arthritis e.g. rheumatoid arthritis, septic arthritis.

 

Action: Perform a patellar tap test to see if you can detect the presence of an effusion.

a. With the patient’s knee extended, slide your left hand down the thigh to the upper border of the patella.  This pushes any potential synovial fluid from the suprapatellar pouch behind the patella.

b. Keep your left hand there and then use your right hand to push downwards on the patella

c. If there is fluid present you will feel a tap as the patella bumps against the femur.

Assess for:

–> Joint Effusion: This test is used to assess for a joint effusion. This is caused by an inflammatory process in the knee joint which can occur for a variety of reasons. These include trauma (e.g. damage to the ligaments), osteoarthritis, or an inflammatory arthritis like rheumatoid or infection (septic arthritis).

 

Action: Bend both knees to about 30 degrees so they are mildly flexed. Palpate around the joint line, feeling for the following structures in order. Start with the normal leg and then examine the knee which is symptomatic.

a. Patella margins: Start at the the top of the patella and using both hands, feel around the medial and lateral patella facets

b. Patella stability: Apply medial and lateral pressure to see if there is medial/lateral laxity in the patella, which would increase the risk of a patella dislocation. 

c. Joint Line: Next, feel around the medial and lateral aspect of the joint line, working anterior to posterior on both sides.

d. Tibial tuberosity: Press on the tibial tuberosity to assess for tenderness.

e. Head of fibula: Work laterally to feel the fibula head. Tenderness here may be indicative of a head of fibula fracture.

f. Popliteal fossa: Using your fingers, push into the popliteal possa to see if you can feel a mass. If you can try to assess whether it is pulsatile.

Assess for:

–> Tenderness: This may indicate an inflammatory process or something more acute like a fracture. It is important to localise the tenderness as different pathologies give pain in different areas.

–> Tibial tuberosity tenderness: This is seen in Osgood-Schlatter disease.

–> Baker’s cyst/popliteal aneurysm: These will both give palpable masses in the popliteal fossae.

Move

In the MSK examinations, we assess both active (patient doing the movement unaided) and passive movement (where the examiner does the movement for them). This is because different pathologies will produce pain on active or passive movement, or sometimes both. This is crucial in helping the clinician to diagnose the condition. 

–> Pain on active movement – Tendon issues, muscle conditions

–> Pain on passive and active movement – Joint conditions, fractures

ACTIVE MOVEMENT:

Action: To test the movements, make the bed completely flat to allow for a full ROM. Test each leg in turn. 

a. Knee Flexion – Ask the patient to bend their knee and bring it towards their chest ensuring that they keep their heel touching the couch. (Normal ROM = 135 degrees)

b. Knee extension –  Ask patient to straighten their leg and extend their knee as much as possible (Normal ROM = 5 degrees)

PASSIVE MOVEMENT:

This time, ask the patient to relax and allow you to move the joint freely. To help achieve this, start by rolling each leg side to side gently to make the leg floppy.  When doing passive movement, keep one hand on the knee so you can feel for any crepitus in the joint. 

Actions:

a. Knee flexion: Support the leg and flex the knee bringing the knee towards the patient’s chest. 

b. Hip Internal and External Rotation: Whilst the hip is flexed to 90 degrees, turn the knee inwards to internally rotate the hip (Normal ROM = 30 degrees) and then outwards to externally rotate the hip (normal ROM = 40 degrees). This is required so you can quickly screen for any disease in the hip.

c. Knee hyperextension: Fully extend the knee. Elevate the leg by the heel and note if there is any hyperextension in the joint. (This is extension > 10 degrees)

Assess for:

–> Crepitus: This is a sensation or noise when you move a joint which can be described as clicking, cracking, creaking, crunching, grating or popping. The sound is heard when two rough surfaces come into contact—for example, in osteoarthritis or rheumatoid arthritis when the cartilage around joints erodes and the surfaces in the joint grind against one another. Therefore, could be a sign of arthritis in the hip joint. 

–> Range of Motion: For each movement, assess whether the patient has a normal range of motion. When assessing this, try and distinguish whether this the ROM is limited due to a structural abnormality or pain. 

 

Knee Flexion

Hip Internal and External Rotation

Special tests

Action: Test the CRUCIATE LIGAMENTS using anterior and posterior drawer tests

Anterior Drawer Test

This is a test which is used to assess the anterior cruciate ligament. This ligament prevents anterior displacement  of the tibia on the femur.

a. With the patient lying down on the couch, ask the patient to bend both knees so that they are flexed at 90 degrees. 

b. You may ask the patient if you can sit on the bed and rest your arms of the patient’s shins to support their legs.

c. Starting on the right leg , place both thumbs on the tibial tuberosity and wrap your fingers round the back of the leg.

d. Pull the tibia anteriorly on the femur

e. Repeat the steps on the left leg.

Assess for:

–> Anterior movement of tibia: Significant laxity of the tibia may suggest a tear or rupture of the ACL. 

Posterior Drawer Test

This is a test which is used to assess the posterior cruciate ligament. This ligament prevents posterior displacement  of the tibia on the femur.

a. Use the same method as the anterior drawer test

b. This time push the tibia posteriorly. 

Assess for:

–> Posteriorly movement of tibia: Significant laxity of the tibia may suggest a tear or rupture of the PCL.

A similar test is Lachmann’s test (shown below) which can be used to asses the ACL and PCL. It is very similar except the knee is flexed to 30 degrees. 

 

Collateral Ligaments

Action: Test the COLLATERAL LIGAMENTS of the knee:

a. Ask the person to fully extend both legs and relax them.

b. Starting with the right leg, pick it up and support it, hold the patient’s ankle in between your right elbow and right hip.

c. With your left hand, use this to hold the knee joint. 

d. Test the MCL – Apply inward pressure on the lateral aspect of the knee joint whilst you push out with your right hand. 

e. Test the LCL – Move your left hand over onto the medial apsect of the knee joint. This time, apply outward pressure on the medial aspect of the knee joint whilst you pull in with your right hand

f. Repeat the steps on the other leg. 

Assess for:

–> Collateral ligament laxity: Increased laxity is a sign of damage to the collateral ligaments. This will be seen as the medial or lateral aspect of the joint will open up when valgus/varus stress is applied. 

– Laxity with valgus stress = dysfunction to MCL

– Laxity with varus stress = dysfunction to LCL

 

McMurray’s Test

McMurray’s test is used to assess the menisci for evidence of a tear to the menisci. Before performing this test, you should ask permission from the OSCE examiner – this is because it can cause significant pain to the patient and injure them. However, you may be asked questions about the test. 

Action: Offer McMurray’s test to assess the menisci of the knee.

a. Starting on the right knee, hold the knee and passively flex it as far as the patient can tolerate. 

b. Hold the patient’s foot with your right hand. 

c. Test Lateral Meniscus – Internally rotate the foot and apply valgus stress on the knee by pushing inwards with your left hand. Slowly extend the foot and observe for pain. 

d. Test Medial meniscus – Externally rotate the foot and apply varus on the knee by pushing outward with your left hand. Slowly extend the foot and observe for pain. 

e. Do the same thing on the other leg. 

Assess for:

–> Discomfort: Sharp discomfort is suggestive of a meniscal tear.

– Discomfort with foot externally rotated + varus stress applied –> medial meniscus tear

– Discomfort with foot internally rotated + valgus stress applied –> lateral meniscus tear

Thank the patient and wash your hands again!

On Completion

You must remember that the physical examination is only one part of the overall assessment of your patient. Therefore, when completing your exam, state that you would do the following in order to complete your assessment of the patient. Much of this will depend on whether you have discovered any particular findings or have an idea about the overall diagnosis. However, some essential things to talk about are:

“To complete the examination, I would do a number of steps…”

Bedside:

  • (History) Take a full history
  • (Observations) Examine neurovascular state of both limbs e.g. pulse, sensation, proprioception
  • (Corresponding examination)  Examine joint above and below (hip and ankle)

Bloods – Would take a full blood count, inflammatory markers

Imaging – AP and lateral radiographs of the knees 

How to Present Your Findings

“I conducted a hip examination on … who seemed well and comfortable at rest.

  • On inspection there were no peripheral signs or paraphernalia of MSK disease
  • The gait was smooth with a normal swing and stance phase
  • There were no visible abnromalities
  • The knee was non-tender on palpation and there was no effusion
  • There was normal range of active and passive motion in the knee
  • Anterior and posterior drawer tests were normal, no abnormalities in knee ligaments

In summary, this is a normal knee examination.”

Sources

Gait Cycle –  Ducky2315, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Knee Effusion – James Heilman, MD, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Valgus Knee Deformity – BioMed Central, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

Varus Deformity – Ellen L Tsay, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Popliteal fossa Swelling – Low-grade fibromyxoid sarcoma in a child presenting as a popliteal fossa swelling – Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Clinical-photograph-of-the-right-popliteal-fossa-swelling_fig1_321974632 

Pes Planus – Hellerhoff, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Pes Cavus – Benefros at English Wikipedia, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons

Total Knee Replacement – User:Ravedave, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons

Knee Arthroscopy Scars – Tim1965, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Patella Taphttps://www.versusarthritis.org/about-arthritis/healthcare-professionals/training-and-education-resources/clinical-assessment-of-patients-with-musculoskeletal-conditions/the-musculoskeletal-examination-rems/examination-of-the-knee/

Knee Flexion – Mapommered, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Hip internal and external rotation – https://vahvafitness.com/unilateral-hip-rotation-for-maximal-performance/

Drawer Test – Mak-Ham Lam, Daniel TP Fong, Patrick SH Yung, Eric PY Ho, Wood-Yee Chan and Kai-Ming Chan, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons

Varus Stress Test – Jorge Chahla, Posterolateral Corner of the Knee: Current Concepts – Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Demonstration-of-the-varus-stress-test-a-performed-at-0-degrees-of-knee-flexion-and-b_fig3_299484988

McMurray’s test – Alfred Atanda, Injuries and Chronic Conditions of the Knee in Young Athletes – Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/The-McMurray-test-To-assess-for-meniscal-pathology-the-knee-is-hyperflexed-and_fig12_38062380 

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