6.2 Gait Analysis & Pathological Gait Patterns

Gait Analysis & Pathological Gait Patterns

Clinical Core: Observational gait analysis allows the registered massage therapist to assess dynamic kinetic chain function, motor coordination, and compensatory pain adaptations in real time. Recognizing deviations within specific sub-phases of the gait cycle provides essential diagnostic insight into muscle weakness, joint restriction, and underlying neurological impairment.

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1. Biomechanics of the Normal Human Gait Cycle

A complete gait cycle (or stride) is defined as the time interval between two successive occurrences of the same initial event for the same limb—traditionally measured from initial contact (heel strike) of one foot to the subsequent initial contact of that identical foot.

Spatial and Temporal Gait Terminology

• Step Length: The linear distance between the point of initial contact of one foot and the point of initial contact of the opposite foot (normal adult average: 65 to 75 cm).
• Stride Length: The linear distance between two consecutive initial contacts of the same foot (comprising two consecutive step lengths; normal adult average: 130 to 150 cm).
• Cadence: The walking rate expressed in steps per minute (normal average: 90 to 120 steps/min).
• Step Width (Base of Support): The lateral distance between the midpoints of the heels during double support (normal: 5 to 10 cm).
• Angle of Toe-Out: The angle between the direction of progression and the long axis of the foot (normal: 5° to 7°).

+-------------------------------------------------------------------------------------+
|                                 SINGLE GAIT CYCLE (STRIDE)                          |
|                                          100%                                       |
+---------------------------------------------------+---------------------------------+
|                    STANCE PHASE                   |           SWING PHASE           |
|                         60%                       |               40%               |
+---------+---------+-------------+--------+--------+---------+-------------+---------+
| Initial | Loading |  Midstance  | Term.  | Pre-   | Initial |   Midswing  |  Term.  |
| Contact | Resp.   |             | Stance | swing  |  Swing  |             |  Swing  |
| (0%)    | (0-12%) |  (12-31%)   |(31-50%)|(50-60%)|(60-73%) |  (73-87%)   |(87-100%)|
+---------+---------+-------------+--------+--------+---------+-------------+---------+
|<- DLS ->|         |             |        |<-DLS ->|                                 |
| (0-12%) |         |             |        |(50-60%)|                                 |
+---------+---------+-------------+--------+--------+---------------------------------+
  DLS = Double Limb Support (20-24% total cycle duration)

The Stance Phase (60% of Total Cycle)

The stance phase occurs while the reference foot is in direct physical contact with the ground:

1. Initial Contact (Heel Strike, 0%): The moment the calcaneus contacts the ground. The hip is flexed to approximately 30°, the knee is fully extended (or flexed 0°–5°), and the ankle sits in neutral (0° dorsiflexion). The tibialis anterior contracts isometrically and eccentrically to prevent foot slap, while the gluteus maximus and hamstrings contract to stabilize the pelvis and prevent forward trunk collapse.
2. Loading Response (Foot Flat, 0%–12%): The initial double limb support period where body weight transfers entirely onto the stance limb. The ankle moves into 5°–10° of plantarflexion; the tibialis anterior acts eccentrically to decelerate foot descent; the quadriceps femoris contracts eccentrically as the knee flexes to 15° for shock absorption; and the subtalar joint pronates to unlock the midfoot for surface adaptation.
3. Midstance (12%–31%): The beginning of single limb support as the contralateral limb enters swing. The body's center of mass moves directly over the stationary foot. The ankle transitions from plantarflexion into 5°–10° of dorsiflexion; the gastrocnemius and soleus contract eccentrically to control forward tibial advancement (the "ankle rocker"); the hip abductors (gluteus medius and gluteus minimus) contract forcefully on the stance side to stabilize the pelvis in the frontal plane.
4. Terminal Stance (Heel Off, 31%–50%): The heel elevates from the support surface while the forefoot remains anchored. The hip reaches maximum hyperextension (10°–15°); the subtalar joint supinates, locking the transverse tarsal joints to convert the foot into a rigid lever; and the triceps surae switch to concentric contraction to drive propulsion.
5. Preswing (Toe Off, 50%–60%): The final double limb support phase. Rapid unloading occurs as the contralateral foot achieves initial contact. The hallux flexes at the metatarsophalangeal joint through flexor hallucis longus contraction; the hip flexors (iliopsoas and rectus femoris) contract concentrically to initiate limb acceleration into swing.

The Swing Phase (40% of Total Cycle)

The swing phase occurs while the reference foot is entirely airborne, advancing forward:

1. Initial Swing (Acceleration, 60%–73%): Begins as the toes leave the ground. The hip flexes to 15°–20°, the knee flexes rapidly to its maximum of approximately 60° to ensure toe clearance, and the ankle dorsiflexors (tibialis anterior, extensor hallucis longus, extensor digitorum longus) contract concentrically to lift the foot into neutral.
2. Midswing (73%–87%): The swinging limb advances directly past the contralateral stance limb. The tibia achieves a vertical orientation. Hip flexion reaches 25°–30°, the knee extends toward 30°, and active dorsiflexion maintains clearance between the hallux and ground (approximately 1 to 2 cm).
3. Terminal Swing (Deceleration, 87%–100%): The limb decelerates to prepare for heel strike. The hamstrings contract eccentrically to slow the advancing femur and tibia; the quadriceps contract to bring the knee into full extension; and the tibialis anterior positions the ankle in neutral 0° dorsiflexion for initial contact.

Double Limb Support (DLS)

In normal walking, both feet contact the ground simultaneously during two distinct intervals: loading response (0%–12%) and preswing (50%–60%). Combined, double limb support occupies 20% to 24% of the normal walking cycle. As walking speed increases toward running, double support decreases linearly until it disappears completely, replaced by a non-contact float phase.

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2. Joint Kinematics & Determinants of Gait

Efficient locomotion relies on six classic "determinants of gait" that minimize the vertical and lateral excursion of the body's center of mass (normally restricted to a smooth, 5-cm sinusoidal curve):

• Pelvic Rotation: The pelvis rotates approximately 4° forward on the swing side in the transverse plane, lengthening the stride and minimizing the downward dip of the center of mass.
• Pelvic Tilt: The pelvis drops approximately 5° downward on the unsupported swing side in the frontal plane, lowering the crest of the center of mass trajectory (eccentrically controlled by the stance gluteus medius).
• Knee Flexion in Stance: The knee flexes 15° during loading response, absorbing impact shock and dampening vertical crest displacement.
• Foot & Ankle Rockers: The sequential heel rocker (initial contact), ankle rocker (midstance), and forefoot/toe rocker (terminal stance) provide smooth continuous progression without abrupt changes in velocity.
• Lateral Pelvic Displacement: The body shifts laterally 4 to 5 cm toward the weight-bearing stance limb, maintaining the center of gravity over the base of support.

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3. Pathological Gait Patterns

Pathological gaits arise from mechanical joint restrictions, pain avoidance, severe muscle weakness, or central/peripheral nervous system lesions.

1. Antalgic Gait

• Etiology: Pain arising from any weight-bearing joint, bone, ligament, or soft tissue structure in the lower extremity or lumbar spine.
• Biomechanical Mechanism: The patient instinctively minimizes weight-bearing time on the painful limb.
• Clinical Presentation:
  • Markedly shortened stance phase on the affected (painful) limb.
  • Rapid, accelerated swing phase of the affected limb to return to supported rest.
  • Shortened step length on the contralateral (unaffected) limb, because the painful leg cannot endure prolonged single limb support.
  • Asymmetrical cadence and limp.
  • The patient often leans their trunk toward the affected side when hip pathology is present (to reduce abductor joint compression) or guards the limb with a rigid posture.

2. Trendelenburg Gait (Gluteus Medius Lurch)

• Etiology: Weakness, paralysis, or mechanical disruption of the hip abductor complex (gluteus medius and gluteus minimus), caused by superior gluteal nerve lesion (L4–S1), L5 radiculopathy, chronic hip osteoarthritis, or post-surgical trauma.
• Uncompensated Trendelenburg Gait: During the single limb stance phase on the affected side, the weak abductors fail to stabilize the pelvis. The contralateral pelvis drops downward in the frontal plane (positive Trendelenburg sign).
• Compensated Trendelenburg Gait (Duchenne Gait / Gluteal Lurch): To prevent falling, the patient actively lurches their trunk laterally over the affected stance hip. This lateral trunk lean shifts the body's center of gravity directly over the hip joint center, eliminating the gravitational adduction torque and relieving the weak gluteus medius of the need to generate stabilizing force.
• Bilateral Trendelenburg (Waddling Gait): Bilateral abductor weakness (seen in muscular dystrophies or bilateral developmental dysplasia) produces alternating lateral trunk sways with each step.

3. Steppage / Equine Gait (Foot Drop)

• Etiology: Weakness or flaccid paralysis of the anterior compartment ankle dorsiflexors (tibialis anterior, extensor digitorum longus, extensor hallucis longus). Most commonly caused by deep fibular (peroneal) nerve entrapment, common fibular nerve trauma at the fibular head, or an L4–L5 disc herniation/radiculopathy.
• Biomechanical Mechanism: Loss of dorsiflexion causes the foot to drop into plantarflexion and inversion during the swing phase. To prevent the toes from scuffing or catching on the ground, the patient adopts an exaggerated compensatory movement.
• Clinical Presentation:
  • The patient excessively flexes the hip and knee of the swing limb, lifting the leg abnormally high off the ground (mimicking a horse trotting).
  • At initial contact, the foot cannot achieve a normal heel strike; instead, the toes or lateral foot edge touch down first, followed by an audible, unmitigated foot slap caused by the absence of eccentric dorsiflexor deceleration.

4. Hemiplegic / Circumduction Gait

• Etiology: Upper motor neuron (UMN) lesion resulting from a cerebrovascular accident (CVA / stroke), traumatic brain injury, or cerebral palsy.
• Biomechanical Mechanism: Disruption of corticospinal tract inhibition releases primitive spinal reflexes, producing a spastic extensor synergy in the lower extremity (hip extension, adduction, internal rotation; rigid knee extension; ankle plantarflexion and inversion [equinovarus]).
• Clinical Presentation:
  • Because the spastic leg cannot flex at the knee or dorsiflex at the ankle, the limb is functionally elongated.
  • To achieve ground clearance during the swing phase, the patient performs hip hiking (elevation of the ipsilateral hemipelvis via quadratus lumborum) and circumducts the stiff leg outward in a wide, sweeping lateral semicircular arc.
  • The upper extremity is characteristically held in a spastic flexor synergy (adducted shoulder, flexed elbow, pronated forearm, and clenched fist).

5. Ataxic Gait

• Etiology: Dysfunction of the cerebellum (cerebellar ataxia) or severe loss of lower extremity proprioception due to dorsal column lesions or peripheral polyneuropathy (sensory ataxia).
• Cerebellar Ataxia: Broad base of support (>10–15 cm), irregular step length and timing, jerky dysmetric movements, and unsteady, staggering deviations in all directions ("drunken sailor" gait). The patient cannot perform tandem walking (heel-to-toe test).
• Sensory Ataxia: Loss of position sense forces the patient to look down at their feet constantly. The gait is characterized by heavy, forceful "heel-stamping" to elicit mechanical proprioceptive feedback. In sensory ataxia, closing the eyes dramatically worsens the unsteadiness (positive Romberg test), whereas cerebellar ataxia remains unsteady regardless of visual input.

6. Parkinsonian / Festinating Gait

• Etiology: Dopaminergic neuron degeneration in the substantia nigra (Parkinson's disease, Parkinsonism).
• Clinical Presentation:
  • Stooped Posture: Generalized spinal flexion, forward head, and flexed hips and knees.
  • Bradykinesia & Freezing: Marked difficulty initiating gait; feet appear "glued to the floor" (motor block/freezing).
  • Short Shuffling Steps (Petit Pas): Minimal foot clearance with diminished step length and loss of normal heel-to-toe progression.
  • Festination: As the stooped trunk shifts the center of gravity far forward of the base of support, the patient takes progressively faster, involuntary, short scurrying steps to prevent falling forward.
  • En Bloc Turning: The patient turns their entire body rigidly as a single solid unit through 5 to 20 tiny pivoting steps.
  • Loss of Arm Swing: Bilateral absence of reciprocal arm swing; arms held rigidly in slight flexion at the sides.