Examination of the Knee

Summary

Introduction

  • Name and role
  • Confirm patient identity
  • Obtain consent
  • Adequate exposure of legs
  • Identify if patient has any pain at rest/prior to exam

Look

  • General inspection
  • Anterior, right lateral (+left medial), posterior, left lateral (+right medial)
  • Gait

Feel

  • Temperature
  • Joint effusion
  • Palpate with leg extended
  • Palpate with leg flexed

Move

  • Active flexion + extension
  • If active movement is restricted – ensure to complete passive movement for comparison

Special tests

  • Stability tests
  • Menisci – McMurray’s test

Further assessment

  • Neurovascular assessment
  • Briefly examine proximal and distal joints (hip and ankle)
  • Mention imaging which could be used to further investigate any findings if indicated.

Look

Completed in the standing position

General inspection

  • General comments
    • Any evidence of systemic disease
    • Frailty
    • Body habitus
  • Walking aids
  • Shoes
    • Off the shelf, commercial shoes with no modifications or insoles
    • Wear pattern

Anterior Aspect

Feet together & pointing straight ahead, medial foot borders parallel

  • Alignment
    • Standing limb Alignment
      • physiological valgus alignment
        • 7° in women & 5° in men
    • Knees
      • genu valgum
      • genu varum
      • windswept deformity (one knee in extreme varus and the other in extreme valgus alignment)
    • Patella
      • squinting patellae (indicates excessive femoral anteversion, where compensatory tibial ER allows the feet to point forwards/primary tibial external torsion with hip IR)
      • outfacing or “Frog eyed” (habitual subluxation/dislocation, femoral retroversion)
  • Foot
      • rotation
      • symmetrical ER
  • Skin changes
    • scars and wounds (comment on stage of healing)
    • atrophic changes to the lower limb (hair loss, venous hyperpigmentation, dry skin)
    • psoriasis plaques
    • erythema
    • varicosities
  • Muscle
    • quadriceps wasting
    • ?inflammation/swelling
    • prominent tibial tuberosity (Osgood Schlatter)

If all appears normal: “In the coronal plane the patient has normal anatomical limb alignment, symmetrical lower limbs with no atrophy & no evidence of surgical scars”

Lateral Aspect

Ask the patient to turn 90 degrees, inspect first with feet together and a fully straightened knee. Then ask patient to take a step forward so you can inspect the medial aspect of the contralateral knee.

  • Alignment
    • spine
    • pelvis
    • hip
    • knee
      • fixed flexion ?effusion, entrapped meniscus, loose bodies
      • hyperextension ?cruciate ligament injury
    • ankle
    • foot
  • Skin changes
    • scars and wounds
    • erythema
  • Swelling

Posterior Aspect

Ask the patient to turn another 90 degrees, so that their back is now facing you and lift patient’s shirt – looking for spinal abnormalities + cutaneous manifestation of spinal pathologies

  • Alignment
    • spine (sagittal deformities)
    • level of pelvis ?symmetrical
    • buttock folds
    • popliteal creases
    • hindfoot
    • forefoot rotation
  • Skin changes
    • scars
    • psoriasis plaques, eczema
  • Muscle wasting
    • hamstring
    • calves
  • Swelling
    • popliteal effusions ?Baker’s cyst and other cysts, popliteal aneurysms

Ask the patient to turn a further 90 degrees to inspect the lateral aspect of the opposite leg compared to the one that was inspected earlier.

Gait

Ask the patient to walk up and down the examination room

  • Assess:
    • Range of movement + speed
    • Limping (VIDEO)
      • Antalgic gait – short stance on affected limb
      • stiff knee gait,
      • short leg gait
      • thrusting gait – knee thrusts laterally due to absence of cartilage
      • Trendelenberg gait
    • Leg length Ax (separate paragraph + video)
    • Weight bearing – ?equal bilateral
    • Excess varus (high medial compartment loading) or valgus thrust
    • Height of steps ?foot drop
  • Additional functional tests:
    • Hop and turn assesses stability
    • Duck walking (walking in a squatted manner) assesses menisci
    • Ask pt to replicate clicking mechanism

As you ask the patient to sit and lie down – re-inspect for quadriceps wasting, knee + patella alignment (best completed at 90 degrees of flexion)

Feel

Temperature

  • compare knee joint temperature with the back of the hand

Quadriceps bulk

  • Measure quadriceps bulk at equal distance above patella to identify subtle quadriceps wasting

Joint Effusion

  • Patella tap – With knee fully extended, compress suprapatella bursa and push down on patella with other hand. Ballotable patella is a positive test
  • Bulge/swipe test – With knee fully extended, compress suprapatella bursa and stroke groove lateral to patella forcing fluid to accumulate in the opposite side and vice versa. Bulging of the opposite side is a positive test

Palpation in extension

  • patella facets (medial and lateral) – ?osteophytes, tenderness
  • medial and lateral joint lines
  • quadriceps tendon

Palpation in flexion – 90 degrees

Ensure to communicate to the examiner the structures that you are palpating. Look at patient’s face whilst palpating. Might need to compare to other knee for pain assessment

  • Anterior Aspect
    • Inferior pole of patella
    • Patella tendon – ?tendonitis
    • Retropatellar fat pad
    • Tibial tuberosity
  • Medial Aspect
    • medial joint line
    • medial collateral ligament
      • origin
      • insertion
    • Pes Anserinus
  • Lateral Aspect
    • lateral joint line
    • lateral collateral ligament
      • origin
      • insertion
    • iliotibial band & gerdy’s tubercle
    • biceps tendon insertion & fibula head
  • Posterior Aspect
    • Baker’s cyst
    • Popliteal aneurysm

Move

Active

  • flexion – heel to buttock
    • ROM 0-130 degrees
  • extension – leg should be flat on bed
    • assess for recurvatum (hyperextension ~>10 degrees)
      • Put force on knee with hand and lift the foot
    • assess for fixed flexion – ensure nil fixed flexion deformity of the hip
    • prone hanging test can help quantify the degree of hyperextension/fixed flexion

Passive

  • feel for crepitus
  • compare passive and active ROM

Special Tests

Stability tests

  • valgus stress test
    • test in 15° flexion
      • relaxes PM capsule
    • test in full extension
      • +ve then damage to
        • sup/deep MCL
        • PM capsule
        • cruciate ligament injury
  • varus stress test
    • N: physiological varus laxity of 3-5 mm
  • Anterior Laxity
    • First check for Posterior sag
      • 90 degrees – run thumbs down medial aspect of condyle and tibial plateau, feeling for ridge
    • Lachman’s test
      • Ask patient to relax leg as much as possible
      • 15° flexion
      • normal: nil or 1-2 mm of translation with very firm endpoint
      • Tip: hand on the femur can also detect tight hamstrings, if tight – tell patient to relax. Can use knee as fulcrum if large thigh (VIDEO)
      • Grade
        • 0: 0-3mm
        • 1: 3-5
        • 2: 5-10
        • 3: >10 with no endpoint
  • Anterior drawer test
    • normal: few mm movement with hard endpoint
    • hamstrings can mask ACL rupture in this test if patient not relaxed
    • some normal ACL’s can have translation in this test
    • more specific for anterior fibres
    • Assess: degree of translation and endpoint
      • 30° IR
        • PLC / lateral complex should tighten & in the normal knee reduce anterior drawer
        • abnormal laxity= injury to posterolateral corner
      • 15° ER
        • PMC / medial complex should become tight – abnormal laxity = injury to posteromedial corner
  • Pivot shift test
    • Knee in full extension + tibia internally rotated, apply valgus force and flex knee to 25-30 degrees
    • Positive test is subluxation of the lateral tibial plateau

Posterolateral laxity

  • Injury
    • LCL
    • popliteus tendon
    • posterolateral ligament complex
  • Results in:
    • tibia rotates externally an abnormal amount with respect to femur
    • lateral tib plateau subluxes posteriorly with respect to lateral femoral condyle
  • Dial Test: Tibial external rotation test (Crank / Dial Test)
    • prone, knees flexed at 30° –> knees flexed at 90°
    • foot is forcefully rotated externally
    • degree of rotation of the medial border of the foot is measured relative to the femur + compared with the contralateral side
    • NB palpate the tibial plateau to determine its relative position to the femoral condyles – this is to confirm that the ↑ ER is due to posterolateral instability rather than anteromed instability
    • NB considerable interindividual variation in degree of maximal ER
      • at 30° flexion: average 30 degrees, range 15-45 degrees
      • at 90° flexion: average 37 degrees, range 15-70 degrees
      • > 10° difference is positive
        ↑ ER at 30° & 90° → combined instability
        ↑ ER which is max at 30° → isolated PL corner injury
  • External Rotation Recurvatum Test
    • knees extended
    • grab both great toes & lift foot off table
    • +ve: abn knee falls into recurvatum & varus, tibia ER compared to normal knee
    • due to injury to PCL, LCL & posterolateral ligament complex & patients will have varus recurvatum gait

Meniscus injury

  • McMurray’s test
    • medial: flex to 90 degrees, hand on medial joint line, evert the foot – apply varus force to medial joint line
    • lateral: flex to 90 degrees, hand on lateral joint line, invert the foot – apply valgus force to lateral joint line
    • pain, clicking, popping = positive test

Patellofemoral joint

  • assess apprehension on mobilising – especially lateral mobilisation (at 0 and/or 30 deg)
  • patella tracking (J tracking) + patella crepitus

Extra tests

Reverse pivot shift test

  • +ve with acute or chronic posterolateral instability
  • Lateral tibial plateau shifts from a position of posterior subluxation to a position of reduction as the flexed knee is extended under valgus & foot in ER
  • Produces discomfort, stimulates feeling of giving way
  • Significantly positive reverse pivot suggests PCL, the arcuate complex & LCL all torn
  • Disappears in position of tibial internal rotation

Further Assessment

  • Neurovascular assessment
    • Describe dorsalis pedis, posterior tibial, popliteal pulses
    • Ensure sensation is normal in SPN, DPN, TN distributions
  • Briefly examine proximal and distal joints (hip and ankle)
  • Mention imaging which could be used to further investigate any findings if indicated.

References

  • Talley, N. J., & O’Connor, S. The rheumatological examination. In: Clinical examination: A systematic guide to physical diagnosis. Edition 7. Oxford: Blackwell Science. 2014. p. 319-323
  • Shelbourne, K.D., Benedict, F., McCarrol, J.R. and Retting, A.C. (1989) Dynamic Posterior Shift: An Adjuvant in Evaluation of Posterior Tibial Subluxation. The American Journal of Sports Medicine, 17, 275-277
  • Daniel DM, Stone ML, Barnett P, Sachs R. Use of the quadriceps active test to diagnose posterior cruciate-ligament disruption and measure posterior laxity of the knee. J Bone Joint Surg Am. 1988 Mar;70(3):386-91. PMID: 3346263
  • Hughston JC, Norwood LA Jnr. The Posterolateral Drawer Test and External Rotational Recurvatum Test for Posterolateral Rotatory Instability of the Knee, Clinical Orthopaedics and Related Research: March 1980 – Volume 147 – Issue – p 82-87

Contributions:

  • Edited and modified by Francesca Sasanelli – February 2022