2.9 Gait Analysis & Abnormal Gait Patterns

Gait Analysis & Abnormal Gait Patterns

Gait analysis is both a Domain A diagnostic procedure (gait analysis) and a Domain D/D rehab management topic (abnormal gait). Mastery of the gait cycle and deviation patterns lets the physiatrist localize neurologic, musculoskeletal, and prosthetic dysfunction at the bedside.

The Normal Gait Cycle

The six determinants of gait (Saunders)—pelvic rotation, pelvic tilt, knee flexion in stance, foot mechanisms, ankle mechanisms, and lateral pelvic displacement—flatten the center-of-mass trajectory, keeping energy expenditure low (~2.5x body weight peak vertical ground reaction force at ~60% stance).

Abnormal Gait Patterns & Localization

Observation                          Likely Localization
─────────────────────────────────   ─────────────────────────────────
Steppage (foot slap/drop)        →  Common peroneal nerve or L5 radiculopathy
Trendelenburg (pelvic drop)      →  Hip abductor (gluteus medius) weakness
Antalgic (shortened stance)      →  Painful lower limb (hip/knee/foot)
Parkinsonian (festination)       →  Basal ganglia / Parkinsonism
Waddling                          →  Myopathy / proximal muscle weakness
Scissoring                        →  Adductor spasticity (cerebral palsy, SCI)
Circumduction                     →  Leg length discrepancy or weak dorsiflexors
Vaulting                          →  Functional leg lengthening (e.g., on the short side) / prosthesis issue

• Trendelenburg sign: standing on one leg, the contralateral pelvis drops if the stance-side hip abductors are weak (positive). A compensated Trendelenburg gait shifts the trunk over the affected hip to reduce abductor moment.
• Steppage/foot drop: excessive hip and knee flexion to clear a flail foot; causes include L5 radiculopathy, common peroneal palsy, and Charcot-Marie-Tooth.
• Antalgic gait: shortened stance phase on the painful limb to reduce weight-bearing time; nonspecific but localizes the symptomatic side.
• Parkinsonian gait: reduced step height and arm swing, festination (progressive acceleration), freezing of gait, and turning en bloc.
• Waddling gait: hyperlordosis and pelvic elevation from proximal muscle (hip girdle) weakness, as in muscular dystrophy or myopathy.

Instrumented Gait Analysis

Three-dimensional motion capture quantifies joint kinematics (angles), kinetics (moments and forces via force plates), and dynamic electromyography. Clinical applications include surgical planning in cerebral palsy (e.g., rhizotomy, tendon lengthening), prosthetic/orthotic prescription, and outcome measurement after interventions. Observational gait analysis (e.g., Rancho/Rivermead) remains the bedside standard.

Assistive-Device Biomechanics

A cane used in the contralateral hand to a painful hip reduces hip joint reaction force by lowering the required abductor force: the cane generates a moment that partially counteracts body weight, decreasing gluteus medius demand and joint loading. Axillary crutches should bear weight through the hands, not the axillae (brachial plexus risk). walkers maximize stability at the cost of gait speed and increased upper-limb demand.

Velocity-Dependent Gait Patterns & Neurologic Localization

Neurologic gait deviations reflect lesion level:

Assistive Devices & Energy Cost

Assistive devices increase stability but raise energy cost and reduce gait speed:

Independent gait  <  Straight cane  <  Quad cane  <  Walker
   (lowest energy cost / highest speed)              (highest energy cost / slowest)

Selection balances stability and energy efficiency: a cane for mild balance/capacity deficits, a walker for marked instability or high fall risk. Crutch gait patterns (four-point, three-point, two-point, swing-through) are chosen by weight-bearing status and bilateral capacity. The physiatrist matches the device to the patient's balance, strength, cognition, and environment.

Prosthetic & Orthotic Gait Analysis

In transtibial and transfemoral amputees, gait analysis identifies prosthetic and alignment issues: vaulting on the sound limb (compensating for a long prosthetic side), lateral trunk bending (short prosthetic side or weak abductors), circumduction (prosthetic knee instability or excessive length), and terminal impact (hard heel at heel strike). In orthotic gait, AFO tuning (stiffness, ankle angle) influences knee stability during stance. Observational and instrumented gait analysis direct alignment and component adjustments.

Clinical Gait Examination Sequence

A structured bedside approach: observe gait from front, side, and back; assess initiation, stepping, turning (high fall-risk), and dual-task performance; evaluate footwear, braces, and assistive devices; perform neurologic and musculoskeletal correlates (Trendelenburg, foot drop, ROM). This synthesis identifies the dominant deviation, localizes pathology, and informs orthotic/prosthetic, medical, and therapy interventions.