National Physical Therapy Examination (NPTE) Quiz: Movement Pattern Analysis
20 questions · exam conditions
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Movement Pattern AnalysisQuestion 1 of 20

After a stroke, rising needs trunk lean right and arm push; left knee hyperextends. Pattern indicates:

Right hip abductor weakness
Left quadriceps weakness
Left dorsiflexor weakness
Left gluteus maximus weakness
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National Physical Therapy Examination (NPTE) Quiz

National Physical Therapy Examination (NPTE) Quiz: Movement Pattern Analysis

Practice Movement Pattern Analysis in National Physical Therapy Examination (NPTE) with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Movement Pattern Analysis, giving you a quick way to practice the rules, question types, and explanations that matter most for National Physical Therapy Examination (NPTE).

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

After a stroke, rising needs trunk lean right and arm push; left knee hyperextends. Pattern indicates:

  1. Right hip abductor weakness
  2. Left quadriceps weakness (correct answer)
  3. Left dorsiflexor weakness
  4. Left gluteus maximus weakness
Explanation: During rising, the left quadriceps normally controls knee flexion and then extends the knee. If it is weak, you lock the knee back into hyperextension to keep it stable, while leaning the trunk right and pushing with the right arm to unload the weak leg. A tempting trap is left dorsiflexor weakness, but that causes foot drop, not knee hyperextension.

Question 2

During overhead squat, heels rise early and trunk drifts forward. This pattern best indicates:

  1. Hip flexion range deficit
  2. Thoracic extension deficit
  3. Ankle dorsiflexion deficit (correct answer)
  4. Shoulder flexion deficit
Explanation: Heels rising early means your ankles cannot dorsiflex enough to keep your heels down as your knees move forward, so the trunk drifts forward to compensate. This is the classic overhead squat pattern of ankle dorsiflexion deficit. Hip flexion tightness is tempting because trunk lean can accompany it, but it wouldn't make your heels lift early.

Question 3

At rest, an adult's abdomen moves inward during inspiration while the rib cage expands. This pattern indicates:

  1. Upper airway obstruction
  2. Diaphragmatic weakness (correct answer)
  3. Pleural restriction
  4. Chest wall restriction
Explanation: During normal inspiration the diaphragm descends and pushes the abdominal wall outward. With diaphragmatic weakness, the diaphragm cannot provide that downward force; when the rib cage expands, the unsupported abdominal contents are pulled inward instead. Upper airway obstruction would cause retractions and stridor, not this abdominal paradox.

Question 4

During arm elevation, scapula wings and shoulder shrugs below 60 degrees. This pattern indicates:

  1. Upper trapezius overactivity
  2. Rotator cuff dysfunction
  3. Latissimus dorsi tightness
  4. Serratus anterior weakness (correct answer)
Explanation: Scapular winging with an early shrug during arm elevation is the classic pattern of serratus anterior weakness. Serratus anterior holds the scapula against the rib cage and upwardly rotates it; when it fails, the scapula lifts off and upper trapezius compensates with a shrug below 60 degrees. Upper trapezius overactivity alone wouldn't cause winging, and rotator cuff dysfunction or latissimus tightness wouldn't produce this low-elevation winging.

Question 5

During left stance, right pelvis drops while trunk shifts left. This pattern indicates:

  1. Left hip abductor weakness (correct answer)
  2. Right hip abductor weakness
  3. Left plantarflexor weakness
  4. Right hip flexor tightness
Explanation: During left stance, the left hip abductors must stabilize the pelvis. If they are weak, the right side of the pelvis drops and you compensate by shifting your trunk over the left leg. The tempting mistake is choosing right hip abductor weakness, but that would cause left pelvic drop during right stance, not this pattern.

Question 6

A patient with a complete T10 spinal cord injury is learning to ambulate with knee-ankle-foot orthoses (KAFOs) and a walker. The physical therapist observes the patient performing a swing-to gait pattern. To advance the legs, the patient pushes down forcefully on the walker, depresses their shoulders, and tucks their chin, lifting the pelvis and lower extremities off the floor to swing them forward.

The effectiveness of this compensatory movement pattern relies MOST heavily on the strength of which two muscle groups to create the pelvic lift?

  1. Serratus anterior and pectoralis minor for scapular protraction and depression.
  2. Pectoralis major and anterior deltoid for shoulder flexion and horizontal adduction.
  3. Triceps brachii and wrist extensors for locking the elbows and stabilizing the hands.
  4. Latissimus dorsi and lower trapezius for shoulder depression and trunk extension. (correct answer)
Explanation: When analyzing compensatory movement patterns for spinal cord injury patients, focus on which muscles remain innervated above the injury level and can generate the forces needed for the specific movement described. For a T10 complete spinal cord injury patient performing a swing-to gait with pelvic lift, the movement requires powerful downward force through the arms to elevate the entire lower body. This lifting action primarily depends on shoulder depression (pulling the shoulders down while the hands remain fixed on the walker) combined with trunk extension to create an upward force on the pelvis and legs. The latissimus dorsi and lower trapezius are perfectly positioned for this task. The latissimus dorsi is a powerful shoulder depressor that can generate significant downward force when the hands are fixed, while the lower trapezius provides additional shoulder depression and helps extend the trunk. Both muscles are innervated well above T10 and remain fully functional. Looking at the incorrect options: A) Serratus anterior and pectoralis minor primarily handle scapular positioning but don't generate the major lifting forces needed. B) Pectoralis major and anterior deltoid would actually work against this movement since shoulder flexion opposes the shoulder depression required. C) Triceps brachii and wrist extensors are important for stabilizing the upper extremity position but don't create the lifting force—they're supporting muscles, not prime movers. Remember that in spinal cord injury questions, identify the primary movement pattern first, then determine which intact muscles above the injury level can best generate those specific forces. Focus on the prime movers, not just the stabilizers.

Question 7

A 73-year-old woman with Parkinson's shows stooped posture and small steps, freezing at doorways; which movement pattern observed suggests postural instability?

  1. Widened base and steady backward stepping during a pull test
  2. Delayed protective stepping with multiple corrective steps backward (correct answer)
  3. Normal righting reactions with single-step recovery
  4. Pain-limited hip flexion during sit-to-stand only
Explanation: This question tests the ability to analyze movement patterns to identify impairments related to system-specific function or dysfunction, focusing on physical therapy examination skills. Recognizing movement impairments requires understanding both the biomechanics and the physiological conditions underlying these patterns, such as muscle strength, joint mobility, and neurological function. In the provided vignette, the patient's stooped posture, small steps, and freezing indicates Parkinson's instability, which is characterized by impaired balance responses. The correct answer, choice B, accurately identifies this impairment because delayed protective stepping with multiple corrections during a pull test signifies postural instability. A common misunderstanding, as shown by choice C, is confusing normal recovery with impaired reactions, often caused by underestimating neurological deficits. To help students master this skill, encourage them to focus on matching symptoms with underlying causes and practice differentiating between primary impairments and compensatory movements. Emphasize the importance of context and detailed observation in clinical settings.

Question 8

A 60-year-old woman with COPD uses a forward-lean "tripod" position after 2 minutes of sweeping; which movement pattern observed suggests reliance on accessory muscles?

  1. Forward trunk lean with arms supported to assist breathing (correct answer)
  2. Upright posture with quiet breathing and no rest breaks
  3. Increased knee valgus during squat to pick up the broom
  4. Cervical rotation limitation during scanning while walking
Explanation: This question tests the ability to analyze movement patterns to identify impairments related to system-specific function or dysfunction, focusing on physical therapy examination skills. Recognizing movement impairments requires understanding both the biomechanics and the physiological conditions underlying these patterns, such as muscle strength, joint mobility, and neurological function. In the provided vignette, the patient's forward-lean tripod position after sweeping indicates COPD compensation, which is characterized by accessory muscle reliance for breathing. The correct answer, choice A, accurately identifies this impairment because forward trunk lean with arm support assists in optimizing respiratory mechanics. A common misunderstanding, as shown by choice B, is confusing compensatory postures with normal upright breathing, often caused by overlooking fatigue signs. To help students master this skill, encourage them to focus on matching symptoms with underlying causes and practice differentiating between primary impairments and compensatory movements. Emphasize the importance of context and detailed observation in clinical settings.

Question 9

A 64-year-old man with COPD uses accessory neck muscles and breathes rapidly during light cycling; which movement pattern suggests impaired breathing mechanics?

  1. Upper chest-dominant breathing with visible sternocleidomastoid activation (correct answer)
  2. Quiet diaphragmatic breathing with slow, controlled exhalation
  3. Symmetrical arm swing with normal trunk rotation during walking
  4. Full shoulder elevation without pain during overhead reach
Explanation: This question tests the ability to analyze movement patterns to identify impairments related to system-specific function or dysfunction, focusing on physical therapy examination skills. Recognizing movement impairments requires understanding both the biomechanics and the physiological conditions underlying these patterns, such as muscle strength, joint mobility, and neurological function. In the provided vignette, the patient's accessory neck muscle use and rapid breathing during cycling indicates COPD mechanics, which is characterized by inefficient ventilation. The correct answer, choice A, accurately identifies this impairment because upper chest-dominant breathing with sternocleidomastoid activation reflects impaired diaphragmatic function. A common misunderstanding, as shown by choice B, is confusing accessory use with normal quiet breathing, often caused by overlooking exertion levels. To help students master this skill, encourage them to focus on matching symptoms with underlying causes and practice differentiating between primary impairments and compensatory movements. Emphasize the importance of context and detailed observation in clinical settings.

Question 10

A 72-year-old woman with Parkinson's shows reduced trunk rotation and minimal arm swing bilaterally; which movement pattern observed suggests bradykinesia?

  1. Slow, small-amplitude movements with difficulty increasing speed (correct answer)
  2. High-stepping gait with excessive hip and knee flexion
  3. Trendelenburg gait with pelvic drop on the swing side
  4. Antalgic gait pattern due to sharp knee pain
Explanation: This question tests the ability to analyze movement patterns to identify impairments related to system-specific function or dysfunction, focusing on physical therapy examination skills. Recognizing movement impairments requires understanding both the biomechanics and the physiological conditions underlying these patterns, such as muscle strength, joint mobility, and neurological function. In the provided vignette, the patient's reduced trunk rotation and minimal arm swing indicates Parkinson's bradykinesia, which is characterized by slowed hypometric movements. The correct answer, choice A, accurately identifies this impairment because slow, small-amplitude movements with speed difficulty are hallmarks of bradykinesia. A common misunderstanding, as shown by choice B, is confusing bradykinetic patterns with high-stepping gaits, often caused by misattributing neurological signs. To help students master this skill, encourage them to focus on matching symptoms with underlying causes and practice differentiating between primary impairments and compensatory movements. Emphasize the importance of context and detailed observation in clinical settings.

Question 11

A physical therapist analyzes the running gait of a 28-year-old marathoner who reports anterolateral knee pain. The video analysis reveals that during the midstance phase on the painful side, the contralateral hip drops approximately 15 degrees. Simultaneously, the ipsilateral femur adducts and internally rotates, and the tibia internally rotates, creating a dynamic knee valgus. The runner's foot appears to maintain a relatively neutral position without excessive pronation.

This observed movement pattern is MOST indicative of which underlying neuromuscular impairment?

  1. Eccentric weakness of the ipsilateral vastus medialis obliquus, failing to control patellar tracking.
  2. Insufficient eccentric control and delayed activation of the ipsilateral gluteus medius and maximus. (correct answer)
  3. Overactivity and tightness of the ipsilateral tensor fasciae latae and iliotibial band.
  4. Limited ankle dorsiflexion range of motion, causing premature and excessive tibial internal rotation.
Explanation: The correct answer is B. The combination of contralateral pelvic drop (Trendelenburg sign), ipsilateral femoral adduction, and internal rotation is a classic presentation of impaired hip abductor and external rotator control. The gluteus medius is the primary frontal plane stabilizer of the pelvis, and the gluteus maximus is a powerful external rotator and extender. Their weakness or delayed activation during the high-load demands of running leads to the collapse of the kinetic chain from the hip downwards. Distractor A is a result of this pattern, not the cause; poor hip control leads to abnormal stress on the patellofemoral joint and can strain the VMO. Distractor C is often a synergist that becomes overactive to compensate for weak gluteals, but it is not the primary driver of the entire pattern. Distractor D is incorrect because the scenario specifies a neutral foot position, making a primary ankle impairment less likely to be the main cause of the pronounced hip and knee deviations.

Question 12

An 82-year-old female is asked to rise from a standard height, armless chair. She begins by shifting her weight forward, but her buttocks do not lift from the chair. She then rocks back and forth three times with increasing momentum before she is able to successfully stand up. Once standing, she is momentarily unsteady. Her medical history is significant for sarcopenia and fear of falling.

The analysis of this movement pattern suggests the patient's primary limiting impairment is MOST likely insufficient:

  1. Hip extension and ankle plantar flexion range of motion.
  2. Generation of lower extremity concentric muscle power. (correct answer)
  3. Anticipatory postural control and motor planning.
  4. Static standing balance and sensory integration.
Explanation: The correct answer is B. The patient is attempting to use a momentum-transfer strategy (rocking) to compensate for an inability to perform a force-control strategy. The force-control strategy relies on generating sufficient lower extremity muscle force (primarily quadriceps and gluteals) to lift the body's center of mass. Her failure on the initial attempt and subsequent need to generate momentum via rocking strongly indicates that the primary impairment is a lack of concentric muscle power to overcome the forces of gravity and inertia. Distractor A is unlikely, as limitations in this range would manifest differently, not as a failure to initiate lift-off. Distractor C is less likely to be primary; while motor planning is involved, the repeated, purposeful rocking shows an intact (though compensatory) motor plan. The primary failure is in the execution phase due to force deficit. Distractor D relates to her unsteadiness after standing, which is a separate issue from the inability to rise from the chair itself.

Question 13

A patient with a diagnosis of C6 tetraplegia is propelling a manual wheelchair on a level surface. The physical therapist observes that the patient uses long, arcing strokes. The propulsion phase begins with the hands well behind the top-dead-center of the pushrim and concludes with a forceful push forward and downward. The recovery phase is a circular pattern below the pushrim. The therapist notes significant shoulder internal rotation and adduction during the propulsive phase.

This observed propulsion pattern is a necessary adaptation PRIMARILY due to the paralysis of which key muscle groups?

  1. Serratus anterior and lower trapezius, preventing effective scapular stabilization.
  2. Triceps brachii and wrist flexors, preventing a powerful push and grip on the rim. (correct answer)
  3. Latissimus dorsi and teres major, eliminating the ability to extend and adduct the shoulder.
  4. Pectoralis major (sternal head) and posterior deltoid, limiting shoulder extension.
Explanation: The correct answer is B. A patient with a C6 spinal cord injury has innervation of the shoulder musculature, elbow flexors, and wrist extensors (allowing for tenodesis grip), but lacks innervation to the triceps brachii (elbow extensors) and wrist flexors. The long, arcing pattern is a compensation to generate momentum without active elbow extension. The forceful push relies on the innervated anterior deltoid and clavicular head of the pectoralis major. The lack of triceps prevents a powerful straightening of the elbow at the end of the push, and the lack of active wrist flexion requires the use of a tenodesis grip or friction on the palms. Distractors A, C, and D list muscles that are generally innervated at the C6 level and are therefore functional, even if somewhat weak.

Question 14

A patient with a right transtibial prosthesis is ambulating. During the loading response on the prosthetic side (from initial contact to midstance), the therapist observes that the knee flexes excessively and rapidly, creating a sensation of instability for the patient. The patient has a long residual limb and good muscular control.

Assuming the patient's knee extensors are of adequate strength, which prosthetic misalignment or component issue is the MOST likely cause of this gait deviation?

  1. The prosthetic foot is aligned in excessive plantar flexion.
  2. The heel cushion of the prosthetic foot is excessively firm.
  3. The prosthetic socket is set too far anterior to the foot.
  4. The prosthetic foot is aligned in excessive dorsiflexion. (correct answer)
Explanation: The correct answer is D. Excessive knee flexion during early stance is a classic sign that the prosthetic foot is aligned in too much dorsiflexion. This alignment creates a strong flexion moment at the knee as soon as the heel contacts the ground, causing the knee to buckle if the quadriceps cannot control it. The ground reaction force vector passes posterior to the knee joint axis, promoting flexion. Distractor A (excessive plantar flexion) would cause the opposite problem: insufficient knee flexion or knee hyperextension. Distractor B (firm heel) would also cause insufficient knee flexion because it would delay the foot from getting flat on the floor, keeping the ground reaction force anterior to the knee. Distractor C (socket anterior to foot) would increase the extension moment at the knee, leading to hyperextension, as it shifts the patient's weight further forward over the foot.

Question 15

A 7-year-old child with spastic diplegic cerebral palsy ambulates with a walker. The physical therapist observes a crouch gait pattern, characterized by excessive flexion at the hips and knees throughout the gait cycle, combined with an equinus position of the ankles. The child demonstrates a positive Duncan-Ely test bilaterally.

Given these findings, the excessive hip and knee flexion component of the crouch gait is MOST likely driven by spasticity of which muscle?

  1. Iliopsoas, which causes a primary flexion moment at the hip.
  2. Hamstrings, which cause a primary flexion moment at the knee and extension at the hip.
  3. Rectus femoris, which, when spastic, limits knee flexion in the swing phase and pulls the pelvis anteriorly. (correct answer)
  4. Gastrocnemius, which, when in a fixed equinus contracture, forces a compensatory knee flexion.
Explanation: The correct answer is C. A positive Duncan-Ely test is a specific test for rectus femoris spasticity or contracture. When the patient is prone and the knee is passively flexed, a spastic rectus femoris will cause the hip to flex and the pelvis to tilt anteriorly. In gait, this spasticity contributes significantly to the crouch pattern. It restricts knee flexion during swing, leading to compensatory hip hiking or circumduction. More importantly, during stance, the pull of the spastic rectus femoris across the hip contributes to the anterior pelvic tilt and hip flexion, which in turn necessitates compensatory knee flexion to keep the center of mass over the base of support. While hamstring (B) and iliopsoas (A) spasticity also contribute to crouch gait, the positive Duncan-Ely test specifically implicates the rectus femoris as a major driver of the complex pattern.

Question 16

A patient is recovering from an acute unilateral vestibular neuritis affecting the right side. The physical therapist asks the patient to walk down a hallway and, on command, to turn their head quickly to the right. As the patient turns their head, they exhibit a significant lateral deviation in their walking path toward the right and momentarily lose their balance, widening their base of support.

This loss of postural stability during a head turn is a direct result of dysfunction in the:

  1. Vestibulo-ocular reflex (VOR), leading to oscillopsia and retinal slip.
  2. Vestibulospinal reflex (VSR), leading to an inability to stabilize the body in response to vestibular input. (correct answer)
  3. Cervico-ocular reflex (COR), causing a mismatch between neck proprioception and visual input.
  4. Somatosensory system, due to altered plantar sensation during the dynamic task.
Explanation: The correct answer is B. The vestibulospinal reflex (VSR) is responsible for adjusting posture and stabilizing the body to maintain balance during head movements. With a right unilateral vestibular hypofunction, a quick head turn to the right provides inaccurate information from the right labyrinth. The CNS interprets this as a falling or turning motion, and the faulty VSR generates inappropriate motor commands to the trunk and limbs, causing the veer and loss of balance. While the VOR (A) is also affected and causes gaze instability (oscillopsia), the primary reason for the loss of walking path and postural control is the VSR. The COR (C) is a much weaker reflex and plays a minor role. Somatosensory input (D) is important for balance but is not the primary system impaired in this diagnosis.

Question 17

During a gait analysis of a patient with chronic right-sided hip osteoarthritis, the physical therapist observes a distinctive pattern. During the stance phase on the right leg, the patient demonstrates a significant and rapid lateral shift of the upper body over the right hip. This movement is more pronounced as the patient's reported pain increases.

This compensatory movement pattern, known as a gluteus medius lurch or antalgic gait, serves what primary biomechanical purpose?

  1. To decrease the joint reaction force at the hip by shifting the body's center of mass closer to the joint's center of rotation. (correct answer)
  2. To advance the swing limb more efficiently by creating momentum with the upper body.
  3. To reduce the need for hip extensor muscle activation by locking the hip joint with the iliofemoral ligament.
  4. To increase the activation of the ipsilateral gluteus medius muscle to provide greater stability to the painful joint.
Explanation: The correct answer is A. The joint reaction force at the hip during single-limb stance is a product of body weight and the force generated by the hip abductor muscles (primarily gluteus medius). The abductors create a large compressive force to counteract the adduction torque created by gravity acting on the body's center of mass. By leaning the trunk laterally over the stance hip, the patient shifts the body's center of mass closer to the hip joint. This reduces the adduction torque, which in turn decreases the amount of force the gluteus medius must generate to keep the pelvis level. Reducing both the muscle force and the gravitational torque significantly decreases the overall joint reaction force, thus reducing pain. This is a pain-avoidance strategy. Distractor D is the opposite of what occurs; the goal is to reduce the demand on the gluteus medius.

Question 18

A patient presents with shoulder pain. During active shoulder abduction, the physical therapist observes that the movement is initiated by shrugging the shoulder, and significant superior migration of the humeral head is palpable. The patient achieves only 120 degrees of abduction, with the final degrees accomplished via lateral trunk flexion.

This movement pattern, characterized by a dominant upper trapezius and early superior humeral head migration, is MOST indicative of a force couple imbalance caused by:

  1. Weakness of the deltoid with compensatory overuse of the supraspinatus.
  2. Tightness of the levator scapulae and pectoralis minor muscles, altering scapular kinematics.
  3. Overactivity of the latissimus dorsi and teres major, which restrict full elevation.
  4. Weakness or insufficiency of the rotator cuff muscles and weakness of the serratus anterior. (correct answer)
Explanation: When analyzing abnormal shoulder movement patterns, focus on identifying which muscle groups are failing to perform their normal roles in the coordinated sequence of shoulder elevation. The described pattern reveals a classic force couple dysfunction. Normal shoulder abduction requires precise coordination: the rotator cuff (especially supraspinatus) must compress and depress the humeral head while the deltoid elevates the arm, and the serratus anterior must upwardly rotate and protract the scapula to maintain proper glenohumeral positioning. When this system fails, you see compensatory patterns. The key clinical signs here—shoulder shrugging initiation, superior humeral head migration, limited range (120°), and lateral trunk flexion—indicate that both the rotator cuff and serratus anterior are insufficient. Without adequate rotator cuff depression of the humeral head, it migrates superiorly. Without proper serratus anterior function, the upper trapezius dominates, causing the characteristic shrug pattern and necessitating trunk compensation to achieve terminal range. This makes option D correct. Option A is incorrect because isolated deltoid weakness wouldn't cause superior migration—the issue is lack of humeral head depression, not elevation force. Option B addresses accessory muscle tightness but doesn't explain the primary force couple failure between the rotator cuff and deltoid. Option C focuses on muscles that restrict elevation but doesn't account for the superior migration pattern, which is specifically due to inadequate rotator cuff compression. Remember: Superior humeral head migration during elevation almost always indicates rotator cuff insufficiency, while early scapular elevation suggests serratus anterior weakness—together they create this classic dysfunction pattern.

Question 19

During the loading response and midstance phases of gait, a patient demonstrates excessive and prolonged subtalar joint pronation. The therapist also observes a compensatory increase in internal rotation of the tibia and femur, as well as a slight increase in knee valgus. The patient reports medial shin and knee pain.

This kinetic chain dysfunction is MOST likely initiated by an eccentric weakness of which muscle?

  1. Tibialis anterior, which is responsible for controlling plantar flexion after initial contact.
  2. Fibularis longus, which is a primary evertor of the foot.
  3. Tibialis posterior, which is the primary decelerator of subtalar pronation and internal tibial rotation. (correct answer)
  4. Gastrocnemius, which is responsible for controlling forward progression of the tibia over the foot.
Explanation: The correct answer is C. The tibialis posterior muscle plays a critical role in eccentrically controlling subtalar joint pronation immediately following initial contact. Its tendon passes posterior to the medial malleolus and supports the medial longitudinal arch. Weakness or poor neuromuscular control of this muscle allows the subtalar joint to pronate too far and too fast. This excessive pronation forces the tibia to internally rotate, which in turn drives femoral internal rotation and can lead to a valgus stress at the knee, causing the symptoms described. Tibialis anterior (A) weakness would cause foot slap, not excessive pronation. Fibularis longus (B) is a pronator/evertor, so its overactivity, not weakness, would contribute to the problem. Gastrocnemius (D) weakness would lead to excessive dorsiflexion or a crouch gait, not excessive pronation.

Question 20

A patient with long-standing Parkinson's disease and moderate bilateral knee osteoarthritis is ambulating in the clinic. On a smooth, level surface, the patient demonstrates a mildly festinating gait with short steps. When asked to walk across a plush carpet, the patient's festination dramatically worsens, the step length becomes markedly shorter, trunk flexion increases, and a freezing episode occurs.

The marked exacerbation of the festinating gait pattern on the compliant surface is BEST explained by which interaction?

  1. The compliant surface increases knee pain, causing reflexive inhibition of the quadriceps and leading to a more flexed posture.
  2. The unstable surface demands greater reliance on proprioceptive feedback, which is distorted by the knee OA and poorly processed by the basal ganglia. (correct answer)
  3. The increased friction of the carpet physically resists forward progression of the feet, directly causing the reduced step length.
  4. Visual input is altered by the texture of the carpet, disrupting the patient's use of visual cues to regulate gait speed.
Explanation: The correct answer is B. Patients with Parkinson's disease have impaired internal motor cueing due to basal ganglia dysfunction and become heavily reliant on external feedback (visual, auditory, proprioceptive). Knee osteoarthritis degrades the quality and accuracy of proprioceptive information from the knee joint. On a compliant surface like a plush carpet, somatosensory information from the feet is also dampened, forcing an even greater reliance on joint proprioception to maintain balance and regulate stepping. This combination of distorted proprioceptive input (from OA) and a system that cannot properly process it (basal ganglia) leads to a breakdown in the motor program, resulting in worsened festination and freezing. Distractor A is possible but less likely to be the primary driver of the specific festination pattern. Distractor C is a minor factor. Distractor D is incorrect as the primary sensory change is somatosensory/proprioceptive, not visual.