Gait Assessment
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Direct answer
Sixty per cent stance, forty per cent swing — that split is the skeleton on which the whole gait cycle hangs, with two brief periods of double support (each about ten per cent of the cycle) when both feet share the ground. Assessment follows the cycle from initial contact through loading response, mid and terminal stance and pre-swing, then initial, mid and terminal swing — the Rancho Los Amigos terms — watching each joint in turn for deviation from expected motion, while timing cadence, step length and velocity. A limp is never just a limp: the pattern names the missing muscle, the painful joint or the unstable limb.
What you must remember
- Cycle vocabulary: a step is heel-strike to heel-strike of opposite feet; a stride covers two steps back to the same foot. Cadence averages roughly 100–120 steps per minute, comfortable velocity about 1.3–1.4 metres per second.
- The eight phases in order — initial contact, loading response, mid stance, terminal stance, pre-swing, initial swing, mid swing, terminal swing — with stance covering the first sixty per cent and swing the last forty.
- Key joint events: the knee flexes about 15–18 degrees during loading response to absorb shock, the ankle moves from heel-strike alignment into roughly 10 degrees of dorsiflexion at terminal stance, and the hip extends behind the body before pre-swing.
- Saunders' six determinants of gait — pelvic rotation, pelvic tilt, knee flexion in stance, foot mechanisms, ankle mechanisms and lateral pelvic displacement — collectively flatten the arc of the centre of mass and cut the metabolic cost of walking.
- Muscle timing: tibialis anterior lowers the foot eccentrically after heel strike (its palsy gives foot slap), plantarflexors control tibial advance in terminal stance, and gluteus medius holds the pelvis level in single-limb stance.
- Classic deviations: Trendelenburg (gluteus medius weakness), high steppage (dorsiflexor weakness, classically L4–L5 lesions), circumduction (hemiplegia), antalgic (pain, shortened stance on the affected limb), broad-based ataxic, and parkinsonian festination with reduced arm swing.
- Observation is structured: watch from front, side and behind, barefoot and with footwear, with and without the walking aid, over at least ten metres including a turn.
Reasoning through a Trendelenburg gait
Stand the patient and ask them to lift one foot, holding single-leg stance for 30 seconds. Watch the pelvis, not the leg. If the pelvis drops on the lifted (swing) side, the standing leg's gluteus medius is too weak to hold the pelvis level — a positive Trendelenburg sign on the stance side. During walking, that drop repeats every time the weak side bears weight, and the trunk often lurches toward the stance leg to shift the centre of mass over the failing hip — the compensated Trendelenburg gait.
Now reason through the look-alikes. A short leg produces pelvic drop with a heel-rise on the short side; measure leg lengths. Hip pain produces an antalgic pattern — a quick, unwilling stance phase on the painful limb, opposite of the slow Trendelendrag. Hemiplegia stiffens the limb into extension with circumduction and equinovarus; foot drop clears the ground by excessive hip and knee flexion, the high steppage pattern, and slaps down when the dorsiflexors cannot lower the foot. Each pattern localises the lesion better than any single test, which is why the gait assessment precedes every special test on the ward round.
How the exam frames it
Deviation-to-muscle matching dominates: gluteus medius to Trendelenburg, tibialis anterior to steppage and foot slap, hip extensors to a backward trunk lurch. Percentages and definitions appear as numbers — 60:40 stance-to-swing, double support vanishing at running cadence. Six determinants is a favourite short note ("list and explain the purpose — energy conservation"), and cadence questions catch students who define it in strides per minute instead of steps.
Frequently asked questions
What proportion of the gait cycle is stance phase in normal walking?
About 60 per cent, with swing taking 40 per cent and two double-support periods of roughly 10 per cent each.
Which gait deviation follows gluteus medius weakness?
Trendelenburg gait — pelvis drops on the swing side, with a trunk lurch toward the stance side when compensated.
Which muscle controls foot lowering after heel strike?
Tibialis anterior, working eccentrically; weakness produces foot slap, palsy produces high steppage gait.
How many determinants of gait did Saunders describe, and why do they matter?
Six — they minimise displacement of the body's centre of mass and so reduce the energy cost of walking.
What distinguishes walking from running?
Running has no double-support period; both feet are briefly airborne during the flight phase.