Test: Knee Flexion - Manual Muscle Test

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Background/Purpose

There are three basic muscle tests for the hamstrings at Grades 5 and 4. The clinician should test first for the aggregate of the three hamstring muscles (with the foot in midline). Only if there is deviation (or asymmetry) in the movement or a question in the clinician's mind is there a need to test the medial and lateral hamstrings separately.
Substitutions for knee flexion when the hamstrings are very weak:
Hip flexion substitution: The prone patient may flex the hip to start knee flexion. The buttock on the test side will rise as the hip flexes, and the patient may appear to roll slightly toward supine.
Sartorius substitution: The Sartorius may try to assist with knee flexion, but this causes flexion and external rotation of the hip. Knee flexion when the hip is externally rotated is less difficult because the leg is not raised vertically against gravity.
Gracilis substitution: Action of the Gracilis contributes a hip adduction motion.
Gastrocnemius substitution: Do not permit the patient to use strong plantar flexion in an attempt to substitute with the Gastrocnemius.
If the Biceps femoris is stronger than the medial hamstrings, the leg will externally rotate during knee flexion. Similarly, if the Semitendinosus and Semimembranosus are the stronger components, the leg will internally rotate during knee flexion. This is the situation that, when observed indicates asymmetry and the need to test the medial and lateral hamstrings separately.
In tests for Grades 3 and 2, the knee may be placed in a 10 degree flexed position to start the test when Gastrocnemius weakness is present.
If the hip flexes at the end of the knee flexion range of motion, check for a tight Rectus femoris muscle because this rightness will limit the range of knee flexion.

Procedure

Grade 5 (Normal), Grade 4 (Good), and Grade 3(Fair)
Hamstring Muscles in Aggregate
Position of Patient: Prone with limbs straight and toes hanging over the edge of the table. Test may be started in about 45 degrees of knee flexion.
Position of Clinician: Standing next to limb to be tested. Hand giving resistance is contoured around the posterior surface of the leg just above the ankle. Resistance is applied in the direction of the knee extension for Grades 5 and 4. The other hand is placed over the hamstring tendons on the posterior thigh.
Test: Patient flexes the knee while maintaining leg in the neutral position.
Instructions to Patient: “Bend your knee. Hold it! Don’t let me straighten it.”
Medial Hamstring Test (Semitendinosus and Semimembranosus)
Position of Patient: Prone with knee flexed to less than 90 degrees. Leg in internal rotation.
Position of Clinician: Hand giving resistance grasps the leg at the ankle. Resistance is applied in an oblique direction toward knee extension.
Test: Patient flexes knee, maintaining the leg in internal rotation.
Lateral Hamstring Test (Biceps femoris)
Position of Patient: Prone with knee flexed to less than 90 degrees. Leg is in external rotation.
Position of Clinician: Clinician resists knee flexion at the ankle using a downward and inward force.
Test: Patient flexes knee, maintaining leg in external rotation.
Grading the Hamstring Muscles (Grades 5 to 3)
Grade 5 (Normal) for all three tests: Resistance will be maximal, and the end knee flexion position cannot be broken.
Grade 4 (Good) for all three tests: End knee flexion position is held against strong to moderate resistance.
Grade 3 (Fair) for all three tests: Holds end range position but tolerates no resistance.

Grade 2 (Poor)
Position of Patient: Side-lying with test limb supported by clinician. Lower limb flexed for stability.
Position of Clinician: Standing behind patient at knee level. One arm is used to cradle thigh, providing had support at medial side of knee. Other hand supports the leg at the ankle just above the malleolus.
Test: Patient flexes knee through available range of motion.
Instructions to patient: “Bend your knee.”
Grading for Grade 2 (Poor): Completes available range of motion in side-lying.
Grade 1 (Trace) and Grade 0 (Zero)
Position of Patient: Prone. Limbs are straight with toes extending over end of table. Knee is partially flexed and supported at ankle by clinician.
Position of Clinician: Standing next to test limb at knee level. One hand supports the flexed limb at the ankle. The opposite hand palpates both the medial and lateral hamstring tendons just above the posterior knee.
Test: Patient attempts to flex the knee.
Instructions to Patient: “Try to bend your knee.”
Grading for Grade 1 (Trace): Tendons become prominent, but no visible movement occurs.
Grading for Grade 0 (Zero): No palpable contraction of the muscles, and tendons do not stand out.

Performed: Unilaterally

Dialog

As the knee flexion begins, the tibia rotates medially on the femur. If the tibia is fixed, as in ambulation, the femur rotates laterally to provide knee flexion. Subject lies supine with the hip flexed 90 degrees.

Criteria

• Range of motion 0 degrees to 135 degrees.

Measurement

LOINC Code

0

Scale/Grading

Pass/Fail