KNEE JOINT
KNEE EXTENSION
 Muscle Tested:
* Quadriceps femoris:
- Origins:
1. Rectus femoris:
a) Straight head from anterior inferior iliac spine.
b) Reflected head from groove above rim of acetabulum.
2. Vastus lateralis:
a) Proximal part of inter-trochanteric line.
b) Anterior and inferior borders of greater trochanter.
c) Lateral lip of gluteal tuberosity.
d) Proximal ½ of lateral lip of linea aspera.
e) Lateral inter-muscular septum.
3. Vastus intermedius:
a) Anterior and lateral surfaces of proximal 2/3 of body of femur.
b) Distal ½ of linea aspera.
c) Lateral inter-muscular septum.
4. Vastus medialis:
a) Distal of inter-trochanteric line.
b) Medial lip of linea aspera.
c) Proximal part of medial supracondylar line.
d) Tendons of adductor longus and adductor magnus.
e) Medial inter-muscular septum.
- Common Insertion: Proximal border of patella and through patellar ligament to
tuberosity of tibia.
- Nerve Supply: Femoral Nerve: L2, L3, L4
Range of Motion:
The range of motion of complete extension of the knee joint is of 120o to 130o.
The range of motion may be limited by:
a) Tension of oblique popliteal, cruciate and collateral ligaments of the knee joint.
b) Tension of knee flexor muscles.
Test Procedures:
* Grade 3 “Fair Strength”:
- Patient Starting Position: Sitting with legs over the edge of the table. The affected leg
is away from the therapist, small cushion under the knee. The patient’s hands grasp the
edges of table to stabilize pelvis or if possible cross both arms on the chest.
* Therapist Position and Grasps: The therapist stands beside the table on the side of the
sound leg. To stabilize the pelvis, his proximal hand is placed over the rectus femoris
origin without applying pressure.
- Command: “Raise your lower leg up through full range of motion without medial or
lateral rotation of the hip, Relax:.
* Grade 4 “Good Strength”:
- Patient Starting Position: Same as for “Grade 3”.
- Therapist Position and Grasps: Same as for “Grade 3” plus the distal hand is placed on
the anterior part of the leg just over the ankle joint to give resistance.
- Resistance: Moderate leading resistance is given in a form of pressing down directly
opposing the line of rising.
- Command: Same as “Grade 3”.
* Grade 5 “Normal Strength”:
- Patient Starting Position: Same as for “Grade 4”.
- Therapist Position and Grasps: Same as for “Grade 4”.
- Resistance: Maximum leading resistance is given in a form of pressing down directly
opposing the line of rising plus hold position at the end of the range.
- Command: Same as for “Grade 4” plus “hold” at the end of the range.
* Grade 2 “Poor Strength”:
- Patient Starting Position: Side lying, affected leg down and flexed, the upper leg is
supported.
- Therapist Position and Grasps: The therapist stands behind the patient, the distal hand
support the upper leg, while the proximal hand is placed above the knee joint to stabilize
the thigh. Avoid pressure over quadriceps femoris.
- Command: “Extend your knee by moving your lower leg forward through full ROM,
Relax”.
* Grade 1 and 0 “Trace and Zero Strength”:
- Patient Starting Position: Back lying, affected knee flexed and supported.
- Therapist Position and Grasps: Therapist stands beside the table, the proximal hand
supporting the affected leg under the knee, the distal hand palpates contraction of
quadriceps femoris on its tendon between patella and tuberosity of tibia and also fibers of
muscles.
- Command: “Try to extend your knees by lifting your foot of the table and pushing in
my hand, Relax”.
Effects of Knee Extensor Muscles Weakness:
a) Knee extensors weakness interferes with the functions of going up and down stairs and
incline as well as getting up and down from a sitting position.
b) The weakness results in knee hyperextension, not in the sense that such weakness
permits.
c) A posterior knee position, but in the sense that walking with a weak quadriceps
requires that the patient lock the knee joint by slight hyperextension.
d) Continuous push suddenly by force thrust in the direction of hyperextension in
growing children may result in a very marked degree of deformity.
Effects of Shortness or Contracture:
a) Shortness or contracture of the knee extensor muscles will produce restriction of the
knee flexion.
b) In addition, a shortness of the rectus femoris part of the quadriceps results in a
restriction of the knee flexion when the hip is extended or a restriction of the hip
extension when the knee is flexed.
MANUAL MUSCLE TESTING OF KNEE EXTENSION
Grade 3: Fair Strength
Grade 2: Poor Strength
Grade 4, 5: Good and Normal Strength
Grade 1 & 0: Trace and Zero Strength
KNEE FLEXION
 Muscles Tested:
1. Medial Hamstring Muscles:
a) Semitendinosus.
b) Semimembranosus.
2. Lateral Hamstring Muscles:
c) Biceps femoris: Refer to the chapter on hip extensors for the description of these
muscles.
Accessory Muscles:
1. Popliteal muscle.
2. Sartorius muscle.
3. Gracilis muscle.
4. Gastrocnemius muscle.
Range of Motion:
The range of motion of the knee flexion is of 120o to 130o. The range of motion
may be limited by:
a) Tension of knee extensor muscles, particularly the Rectus Femoris if the hip is
extended.
b) Contact of calf with the posterior surface of the thigh.
Test Procedures:
* Grade 3 “Fair Strength”:
- Patient Starting Position: Prone lying with leg straight.
- Therapist Position and Grasps: Standing beside the table on the side of the affected leg,
proximal hand above the thigh proximal to knee to stabilize thigh medially and laterally
without pressure over the muscle group being tested.
- Command: “Raise your lower leg through full range of motion, Relax”.
Notes:
a) Flexion of knee joint is actively produced up to 90° only against gravity but after that
will be with gravity assistance and produce smoothly by eccentric contraction of
quadriceps muscle.
b) If gastrocnemius is weak, knee may be flexed to 10° for starting position.
c) If biceps femoris is stronger, lower leg will laterally rotate during flexion.
d) If semitendinosus and semimembranosus are stronger, lower leg will medially rotate
during flexion.
* Grade 4 “Good Strength”:
- Patient Starting Position: Same as for “Grade 3”, the sound leg is away from the
therapist.
- Therapist Position and Grasps: Same as for “Grade 3”, near the affected leg, with the
proximal hand stabilize pelvis and the distal hand grasping above ankle to give
resistance.
- Resistance: Moderate leading resistance is given in a form of pressing down directly
opposing the line of rising.
- Command: “Raise your lower leg up through full range of motion, Relax”.
Note:
a) To test biceps femoris only, the lower leg is laterally rotated to put the muscle in a
good alignment.
b) To test semitendinosus and semimembranosus only, the lower leg is rotated medially
to put the muscle in a good alignment.
* Grade 5 “Normal Strength”:
- Patient Starting Position: Same as for “Grade 4”.
- Therapist Position and Grasps: Same as for “Grade 4”.
- Resistance: Maximum leading resistance is given in a form of pressing down directly
opposing the line of rising, plus “hold” position at the end of the range of motions.
- Command: Same as for “Grade 4”, plus “hold” at the end of the range of motion.
* Grade 2 “Poor Strength”:
- Patient Starting Position: Side lying with both legs straight; the upper leg is supported
and the affected leg is down.
- Therapist Position and Grasps: Standing beside the table, the proximal hand supporting
the upper leg. The distal hand is placed above the knee to stabilize the thigh.
- Command: “Move your lower leg backward through full range of motion, Relax”.
Note: Uneven muscular pull will cause rotation of lower leg.
* Grade 1 and 0 “Trace and Zero Strength”:
- Patient Starting Position: Prone lying, with the affected leg is near the therapist with
slightly flexed knee and the lower leg supported.
- Therapist Position and Grasps: Same as for “grade 2”; the distal hand supports the
lower affected leg, while the proximal hand palpates tendon of knee flexor muscles on
back of the thigh, near the knee joint.
- Command: “Try to raise your lower leg up, Relax”.
Effects of Weakness of the Knee Flexor Muscles:
a) Weakness of both medial and lateral hamstrings causes hyperextension of the knee.
When this weakness is bilateral, the pelvis tilts anteriorly and the lumbar spine assumes a
lordotic position. If the weakness is unilateral, a pelvic rotation will result.
b) Weakness of lateral hamstrings causes tendency toward loss of lateral stability of the
knee, allowing a thrust in the direction of bow leg position in weight bearing.
c) Weakness of medial hamstrings decreases the medial stability of the knee and permits
a “knock-knee” position with a tendency toward lateral rotation of the leg on the femur.
Effects of Shortness or Contracture:
a) Contracture of both medial and lateral hamstrings results in a position of knee flexion.
If the contraction is extreme, it will be accompanied by posterior tilting of the pelvis and
flattening of the lumbar curve.
b) Shortness of the hamstrings muscles will cause a restriction of knee extension, when
the hip is flexed or restriction of the hip flexion, when the knee is extended.
Effects Related to Patient Position:
a) Do not expect the subject to hold full knee flexion nor to hold against the same amount
of pressure with the hip extended in prone position, that he could resist with the hip
flexed in the sitting position.
b) The frequent occurrence of muscle cramping during the hamstrings test on nonparalytic individuals is evidence of too much knee flexion in proportion to the amount of
pressure.
c) For maximum pressure, hip flexion should be used by testing in the sitting position.
 Substitution:
1. Substitution of Sartorius action appears in the form of hip flexion, as knee flexion is
initiated.
2. A short rectus femoris limiting knee flexion range of motion will cause hip flexion, as
the knee flexion motion is completed.
MANUAL MUSCLE TESTING FOR KNEE FLEXION
Grade 3: Fair Strength
Grade 4, 5: Good and Normal Strength
Grade 3,4, 5: Deviation medially or laterally indicating a medial or lateral weakness
Grade 2: Poor Strength
Grade 1 & 0: Trace and Zero Strength
ANKLE PLANTAR FLEXION
 Muscle Tested:
1. Soleus muscle:
- Origin:
a) Posterior surface of head of fibula and proximal ½ of its body.
b) Soleal line and middle 1/3 of medial border of tibia.
c) Tendinous arch between tibia and fibula.
- Insertion: With tendon of gastrocnemius into posterior surface of calcaneum.
- Nerve Supply: Tibial nerve, L5, S1, S2.
- Action: Plantar flexes the ankle joint.
2. Gastrocnemius muscle:
- Origins:
* Medial head:
a) Proximal and posterior part of medial condyle adjacent part of femur.
b) Capsule of knee joint.
* Lateral head:
a) Lateral condyle and posterior surface of femur.
b) Capsule of knee joint.
- Insertion: Middle part of posterior surface of calcaneum.
- Nerve Supply: Tibial nerve, S1, S2.
- Actions:
a) Plantar flexes the ankle joint.
b) Assists in the flexion of the knee joint.
3. Plantaris muscle:
- Origins:
a) Distal part of lateral supracondylar line of the femur and adjacent part of its popliteal
surface.
b) Oblique popliteal ligament of the knee joint.
- Insertion: Posterior part of calcaneum.
- Nerve Supply: Tibial nerve, L4, L5, S1.
- Actions:
a) Plantar flexes the ankle joint.
b) Assists in the flexion of the knee joint.
 Accessory Muscles:
1. Tibialis posterior.
2. Peroneus longus.
Fore foot and ankle plantar flexors.
3. Peroneus brevis.
4. Flexor hallucis longus.
Toe, forefoot and ankle plantar flexors.
5. Flexor digitorum longus.
Range of Motion:
The ankle plantar flexion has a range of motion of approximately 40o to 45o. The
range of motion may be limited by:
a) Tension on anterior talo-fibular ligament.
b) Tension of dorsiflexor muscles of the ankle.
c) Contact of posterior portion of the talus bone on the tibia.
Test Procedures (Weight bearing and non-weight bearing tests):
a) Weight bearing test:
* Grade 3 “Fair Strength”:
- Patient Starting Position: Standing on leg to be tested, knee straight.
- Therapist Position: Therapist stands beside the patient.
- Command: “Rise on your toes clearing your heel off the floor, Relax”.
* Grade 4 and 5 “Good and Normal Strength”:
- Patient Starting Position: Same as in “Grade 3”.
- Therapist Position: Same as in “Grade 3”.
- Command: “Rise on your toes through full range of motion, Relax”. Repeat for 4 to 5
times.
Note:
1. To do the test in the weight bearing position, the tibialis posterior and peroneus
longus brevis muscles must be normal or good to give sufficient stabilization to the
forefoot on the ground.
2. A “Good Grade 4” is given, if the patient has difficulty to complete the ROM or if he
fatigues easily.
b) Non Weight Bearing Test:
* Grade 3 “Fair Strength”:
- Patient Starting Position: Prone lying with the foot to be tested over end of the table.
- Therapist Position and Grasps: Standing beside the patient foot. Proximal hand is
placed on the lower leg, proximal to the ankle to stabilize.
- Command: “Pull the heel upward and push backward with your toes, Relax”.
* Grade 4 “Good Strength”:
- Patient Starting Position: Same as in “Grade 3”.
- Therapist Position and Grasps: Same as in “Grade 3” but the proximal hand hold the
sides of the heel and the distal hand is placed on the plantar surface of the forefoot. Both
hands apply resistance.
Resistance: Moderate leading resistance is given simultaneously at the heel and at the
forefoot directly against the lines of motion, the resistance is given through the full range
of motion.
- Command: Same as for “Grade 3”.
* Grade 5 “Normal Strength”:
Same procedures as for “Grade 4” are used but with a maximal resistance and
“hold” position at the end of range of motion.
* Grade 2 “Poor Strength”:
- Patient Starting Position: Side lying with the lateral border of the foot to be tested on
the table.
- Therapist Position and Grasps: Standing beside the table at the level of the patient foot.
Proximal hand grasps the lower leg just above the ankle joint to stabilize it.
- Command: “Push your foot down through full range of motion”.
* Grade 1 and 0 “Trace and Zero Strength”:
Same procedures as for “grade 2” but the therapist palpates the contraction over
the muscle fibers and on the tendon above calcaneum.
Effects of weakness:
Weakness of the plantar flexor muscles results in a hyper-extended position of the
knee as well in a non-weigh bearing position as in standing. During walking, the inability
to rise on toes and consequently to transfer weight normally forwards results in a
“Gastrocnemius limp”.
Results of Contracture and Shortness of Plantar Flexors:
a) Contracture results in an “Equinus” position of the foot and flexion of the knee.
b) Muscle shortness causes restriction of the ankle dorsiflexion when the knee is
extended and a restriction of knee extension when the ankle is dorsi flexed.
MANUAL MUSCLE TESTING FOR KNEE FLEXION FOR ANKLE PLANTER FLXION
Grade 3, 4, 5: Fair, good, Normal Strength
Grade 1, 0: Trace and Zero Strength
(Weight bearing Test)
Grade 3,4, 5: Non weight bearing test