1.3 Normal and Pathological Gait Analysis
Key Takeaways
Use mean step length with cadence in steps per minute and divide by 60 for m/s. With mean stride length and the same cadence, divide by 120 because there are two steps per stride.
In typical comfortable adult walking, stance and swing occupy approximately 60% and 40% of the cycle. Use foot-contact events to identify phases when timing or contact pattern differs.
A ground reaction force produces a joint moment according to its line of action and the joint axis. During typical loading response, the dorsiflexors restrain plantarflexion and the quadriceps restrains knee flexion.
A trunk lean toward the stance hip can reduce the external hip adduction moment. Pelvic drop or trunk lean can guide further assessment of hip strength, pain, motion and control.
Circumduction, vaulting and steppage describe movements. Assess swing clearance, joint motion and neurological function before assigning a cause.
Normal and Pathological Gait Analysis
Observe a full stride from the side and front, then identify the phase in which the deviation occurs. Note walking speed, surface, footwear and devices. Compare findings at similar speeds when practical because speed can affect timing, loading and muscle activity.
Spatial and Temporal Measures
| Measure | What is measured |
|---|---|
| Gait cycle or stride | From initial contact of one foot to the next initial contact of the same foot. |
| Step | From initial contact of one foot to initial contact of the other. A stride contains a right and a left step. |
| Step length | Forward distance between successive contacts of opposite feet. Record side and asymmetry. |
| Stride length | Forward distance between consecutive contacts of the same foot. In straight walking it is the sum of the two successive step lengths. |
| Cadence | Number of steps per minute. |
| Step width | Mediolateral separation of successive foot placements using a consistent landmark and definition. |
For a representative period of straight walking, speed in m/s = cadence × mean step length ÷ 60 when lengths are in metres and cadence is in steps/min. Each stride has two steps, so speed = cadence × mean stride length ÷ 120. Use distance and cadence measured over the same representative interval. In asymmetric gait the mean step length is the mean across both sides, rather than the value for one limb.
Worked example. Right and left steps are 0.62 m and 0.78 m, with a cadence of 100 steps/min. Mean step length is (0.62 + 0.78) ÷ 2 = 0.70 m, and stride length is 1.40 m. Both 100 × 0.70 ÷ 60 and 100 × 1.40 ÷ 120 give 1.17 m/s after rounding. A similar speed can coexist with appreciable step asymmetry. Document both if the goal includes improving symmetry.
Stance, Swing and Functional Phases
Stance begins at contact and ends at toe-off of the reference foot. Swing continues from toe-off to the next contact. A typical comfortable adult walking example is about 60% stance and 40% swing, with two periods of double support totaling about 20%. The reference limb's single support corresponds to contralateral swing. Double support generally decreases as walking speed increases. Aerial running has flight intervals. Slow grounded running can occur without a flight phase.
Rancho Los Amigos terms use events and functional tasks. Heel strike is a possible initial-contact pattern. Foot flat, heel rise and toe-off are events, while loading response, terminal stance and preswing describe periods. The percentages below are approximate landmarks for comfortable walking.
| Phase and approximate cycle point | Event, movement and muscle function |
|---|---|
| Initial contact, 0% | The foot first contacts the floor. In a typical heel-first pattern the hip is flexed, the knee near extension and the ankle near neutral. The limb is prepared for weight acceptance. |
| Loading response, 0–10% | The other foot is still in contact until it leaves the floor. The heel rocker permits progression as the forefoot lowers. Dorsiflexors control ankle plantarflexion, and the quadriceps controls knee flexion during weight acceptance. Hip extensors and abductors help stabilize the limb and pelvis. |
| Midstance, 10–30% | From opposite toe-off until heel rise, the body progresses over the reference foot. The ankle dorsiflexes as the tibia advances over the foot, the ankle rocker. The plantarflexors help control tibial advancement while the knee moves toward extension. |
| Terminal stance, 30–50% | The heel rises and the body progresses over the forefoot until opposite initial contact. The hip extends and plantarflexors contribute to support and forward progression. Net ankle motion and power do not identify the length change of every individual muscle fascicle. |
| Preswing, 50–60% | From opposite contact to reference toe-off. Weight transfers to the other limb, the reference knee flexes and the ankle plantarflexes. This prepares the limb for swing. Several forces and muscle actions contribute to knee motion. |
| Initial swing, 60–73% | The foot leaves the ground and advances toward the other foot. Hip flexion, knee flexion and dorsiflexion toward neutral aid clearance. |
| Midswing, 73–87% | The foot advances past the stance limb until the tibia is approximately vertical. The knee extends from its earlier flexion, and the dorsiflexors help maintain clearance. |
| Terminal swing, 87–100% | The knee approaches extension and the foot prepares to land. The hamstrings help decelerate the limb and the dorsiflexors position the ankle. |
Ground Reaction Forces and Joint Moments
The ground reaction force (GRF) is the ground's force on the foot. A force plate measures components of that force and estimates the centre of pressure. A single foot's vertical trace often shows two peaks separated by a midstance trough. Peak sizes and timing vary with speed. The total vertical force from the ground, minus body weight, equals mass times vertical acceleration. During single support, a vertical force below body weight therefore corresponds to downward acceleration, even when the centre of mass is high.
A GRF contributes an external moment around a joint. In a simplified planar analysis its magnitude is force times the perpendicular distance from its line of action to the axis. During a typical part of loading response, the GRF passes posterior to the ankle and knee. That produces external ankle plantarflexion and knee flexion moments. The dorsiflexors and knee extensors can generate opposing internal moments while those joints move. Exact equality cannot be assumed during acceleration, and individual muscle force cannot be calculated from the GRF alone. Segment weights, inertia and other forces matter.
For example, if an approximately vertical 700 N GRF acts 0.03 m behind the knee axis, the external GRF contribution is a 21 N·m knee flexion moment in the stated geometry. It is not a measurement of the quadriceps moment or force.
Describing Deviations and Checking Causes
| Deviation | What to observe and assess |
|---|---|
| Trendelenburg pattern | During right stance, look for left pelvic drop or a trunk lean toward the right. An ipsilateral lean can bring the force line closer to the stance hip and reduce the external adduction moment. Check hip strength, pain, range and balance before attributing the pattern to weakness. |
| Circumduction | The swing limb advances in an outward arc. Assess knee flexion, ankle dorsiflexion, hip motion and pelvic movement. The observed arc does not establish which impairment caused it. |
| Vaulting | Early heel rise on the stance limb can help the opposite limb clear the ground. Check swing-limb length, knee mobility, brace or prosthesis and ankle clearance. |
| Reduced loading-response knee flexion or knee hyperextension | A patient can adopt a position that places the GRF anterior to the knee, reducing the need for an active extension moment. Check quadriceps control, ankle mechanics, pain and neurological signs. Genu recurvatum has several possible contributors. |
| Steppage and foot slap | High hip and knee flexion can compensate for poor swing dorsiflexion. Foot slap can reflect reduced control of plantarflexion after contact. Assess ankle dorsiflexion, eversion, inversion and sensory distribution to help localize the deficit. |
| Antalgic pattern | A patient may reduce stance time on a painful limb. Record pain and bilateral step lengths rather than assuming a fixed contralateral response. |
Worked assessment. After a fibular neck injury, a patient lifts the right thigh higher during swing and has poor right toe clearance when distracted. Dorsiflexion, toe extension and eversion are weak. That pattern supports examining the common fibular nerve proximal to its two branches. Test inversion and the rest of the neurological examination to help distinguish more proximal involvement. Assess safe walking and whether support is needed while localization and recovery are evaluated.
During loading response, a patient lowers the forefoot and allows controlled knee flexion. Which muscle actions typically restrain these movements?
Concentric tibialis anterior and concentric hamstrings
Isometric gastrocnemius and eccentric rectus abdominis
Eccentric ankle dorsiflexors and eccentric quadriceps
Concentric soleus and concentric quadriceps
During loading response, the upward GRF passes posterior to both ankle and knee axes in the sagittal plane. Which moments does that force contribute?
Ankle dorsiflexion and knee extension
Ankle dorsiflexion and knee flexion
Ankle plantarflexion and knee extension
Ankle plantarflexion and knee flexion
A patient with documented right hip abductor weakness leans the trunk toward the right stance hip. How can that position reduce abductor demand?
It can shorten the external hip adduction moment arm on the right.
It can increase the external hip adduction moment arm on the right.
It necessarily moves the GRF through the right hip axis and removes all abductor demand.
It increases the right hip moment by increasing the length of the femur.
After an injury at the fibular neck, a patient has high stepping, weakness of dorsiflexion and eversion, and reduced sensation over the dorsum of the foot. Which nerve is most consistent with these findings?
Tibial nerve supplying the plantarflexors
Common fibular nerve, affecting deep and superficial fibular branch function
Femoral nerve supplying the knee extensors
Obturator nerve supplying the hip adductors
Sections you finish are checked off in the contents.