MS �& �KNEE HYPEREXTENSION IN GAIT

PRESENTER BIO

Dr. Sarah Andreucci, PT, DPT

• Marquette University
• B.S. in Exercise Physiology (2012)
• Doctorate of Physical Therapy (2014)
• Physical Therapist – mobile pediatric cash-based practice 
• 12 years clinical experience in pediatrics and neuromuscular impairments
• Involved with MS Just Keep Moving Gym since 2021
• Academic Coordinator of Clinical Education and Instructor for the PTA program of Bryant & Stratton College’s Wauwatosa campus

AGENDA

KNEE HYPEREXTENSION IN GAIT

• Evident when the foot initially contacts the ground and the knee goes beyond neutral alignment
• Why? Many reasons!    
1. Weakness
2. Impaired motor control
3. Lack of ankle mobility (restricted dorsiflexion motion)
4. Spasticity

WHY IS THIS COMMON?

• The body is trying to solve a problem.
• This solution serves as a stability strategy in the stance phase of gait.
• By positioning the knee into extension, the limb becomes a rigid post that's less likely to collapse under the weight of the body.
• Provides short term security and reduces the risk of knee buckling...it comes at a cost.

EFFECTS OF KNEE HYPEREXTENSION

• Limits stride length
• Limits walking speed
• Interrupts the transfer of weight between legs
• Reduces gait efficiency
• Overstresses posterior knee joint capsule and tissues

Understanding why it's happening and intentionally choosing interventions to address the underlying issue, may reduce the magnitude or frequency of knee hyperextension/extensor thrust occurring to lessen the body's propensity to depend on the strategy.

1. MUSCLE WEAKNESS

• Key muscle to target:
• Quadriceps
• Calf muscle (gastrocnemius & soleus)

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• Key type of activation
• Closed-chain
• Eccentric

MOVEMENT DIFFERENCES

• Open chain = foot freely moves through space

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• Closed chain = foot is planted
• Knee hyperextension during gait occurs in a closed chain position

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MUSCLE CONTRACTION DIFFERENCES

CONCENTRIC

• Muscle shortens
• Accelerates motions
• Goes against a resistance

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ECCENTRIC

• Muscle lengthens
• Decelerates motions
• Goes in the direction of the resistance to slow it down

THE GAIT CYCLE

TWO PHASES TO FOCUS ON

If quadriceps or calf muscles are weak and cannot adequately control/slow knee flexion under load, the knee may snap back into extension to rely more on passive structures for stability.

QUAD STRENGTHENING – �WHERE TO START?

1. Open chain exercises
• If the knee cannot support body weight without buckling or relying heavily on arms for support, then start with open chain first

PROGRESSION

2. Closed chain exercises

• Sit to stand – start from a higher surface and progress to a lower seat (makes it more difficult)
• Goal: Controlled knee extension, not locking out knee
• Key: SLOW and SYMMETRICAL especially during the lowering phase 

PROGRESSION

• Split Squat
• Front leg = working leg, allow the knee to bend in a slow controlled manner
• Arms should only be used for balance during this exercise, not for body weight support

PROGRESSION

• Eccentric Step Down 
• Slowly tap heel down to the floor
• Keep pelvis level

PROGRESSION

• Against theraband resistance
• Keep leg straight, kick forwards
• Slowly bend knee
• Then reach leg behind into hip extension

CALF STRENGTHENING

• Heel Raises
• Perform with a wall in front of you to reduce compensation of leaning forwards
• Can also perform off a step to start from a stretched position and go through full range
• Progression: with both feet, raise heels up to achieve max height, then stand only on the weaker leg to lower slowly back down

SPECIFICITY

• The nervous system adapts to the demands put on it
• Since gait occurs in weight bearing, closed chain environment, it is important that we mimic that in our strengthening exercises to produce gains to carry over to gait
• Strength matters...and how you train it matters too!

• Aim for:
• 2-3 sets of 8-12 repetitions
• By the end of the exercise, the target muscles should feel fatigued
• Only perform 1-2 strength exercises per muscle group in any given exercise session
• Strength builds capacity...motor control determines how that capacity is used!

2. IMPAIRED MOTOR CONTROL

Motor Control = the ability to coordinate and time muscle activity to produce smooth, efficient movement

• The knee moves through specific ranges of motion during gait during key phases
• Loading response: knee bends slightly to help absorb force
• Midstance: knee moves into more extension, but in a controlled manner, not locked into full extension
• When motor control is impaired, the body defaults to a more stable strategy which is quickly locking directly into full extension
• Body trades movement quality for stability and predictability

STRATEGIES TO IMPROVE MOTOR CONTROL

• Be mindful to keep knee in a slightly bent, unlocked position throughout the day, not just when walking
• Small changes can have meaningful impact

1. Split stance weight shift
• Shift forward, back heel comes up, focus on maintaining small controlled bend on front knee

PROGRESSION

2. Multidirectional Tapping

• Opposite leg taps to the front, to the side, and behind all while maintaining slight bend in knee on stance leg
• It's about CONTROL, not about how far the opposite leg taps

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PROGRESSION

3. Taps on Step

• Target leg = the foot that stays on the floor.
• Place opposite foot up onto step, then back down to the floor

3. ANKLE MOBILITY

IF ANKLE CANNOT DORSIFLEX (MOVE FORWARD) THEN...

• Our leg is a series of links, if mobility is restricted at the ankle (i.e. Spasticity or tightness in the calf muscle), then our knee or hip MUST compensate
• In a closed chain position (foot on the ground) plantarflexing the ankle will hyperextend the knee

QUICK ANKLE MOBILITY TEST

• Place foot about a hand-width away from the wall
• Try to bring your knee forward to touch the wall while keeping your heel in contact with the floor
• If your heel lifts or you need to move your foot closer to the wall to reach, you may have limited ankle mobility

STANDING CALF STRETCHING

Make sure the back foot keeps toes pointing straight forwards!

SEATED CALF STRETCH

OTHER TOOLS TO REDUCE STIFFNESS

JOINT MOBILIZATIONS

• Performed by a physical therapist or physical therapist assistant
• Can help improve joint capsule mobility to increase dorsiflexion range of motion

4. SPASTICITY

• Involuntary muscle contraction triggered by rapid movement
• Primary spastic muscle causing knee hyperextension = calf muscle
• Forces the knee into greater extension

• Emphasize SLOW movement to not provoke spastic response
• Stretching is best with warm muscles
• Hold each stretch for 30-60 seconds, perform 3 repetitions

PUTTING IT TOGETHER

REFERENCES

• Kisner, C. & Colby, L.A. (2023) Therapeutic Exercise Foundation and Techniques. 8e. Philadelphia, PA: F.A. Davis ISBN: 9781719640473
• Lippert, L. (2023). Clinical kinesiology and anatomy (7th ed.). Philadelphia, PA: F.A. Davis. ISBN 978-0-8036-2363-7
• Mission Gait. (2026, June). Understanding knee extension patterns in gait series. YouTube. https://youtu.be/Ts_rLc0jTSo?si=vMVM8ri7scXuKuYJ