With experience many gait deviations can be observed. The difficulty of observing one body part at a time is that multiple movements in multiple segments are occurring concurrently. Checklists, such as the one provided in Box 11.1, are usually helpful to work through, especially when learning. Traditionally, the approach is to observe the limb as it moves through the different periods of the stance phase – heel contact, mid-stance and propulsion. Another approach (Pathokinesiology Service 1993) is to divide gait into weight acceptance (initial contact and loading response), single limb support (period when body progresses over single limb), and swing limb advancement (time when one limb is unloaded and the other limb is loaded) and note variations from normal during these phases.

Box 11.1 Practical observational gait analysis

• Observe for amounts and timing of events

• Look for asymmetry

• Concentrate on one aspect at a time

• Bisection of calcaneus and posterior aspect of leg is often helpful

• A mark on the medial side of the navicular is also helpful

• Be aware that many individuals may consciously or subconsciously alter gait while being observed

• At least an 8–10 m walkway is desirable and provision for watching clients from behind/in front (frontal plane) as well as from the side (sagittal plane)

• Patient should be wearing shorts (have different sizes available in your clinic)

• Observe with and without shoes, and with and without orthoses

Frontal plane observations

Upper body

• Head/eyes level or tilted

• Shoulders level

• Height of finger tips

• Symmetrical arm swing

• Pelvis level or tilted

Lower limb

• Position of knee

• Q angle/patellar position

• Timing of knee motion

• Position of tibia

• Timing of tibial rotation

Foot

• Timing/amount of rearfoot motion

• Timing/amount of heel contact/off

• Timing/amount of midfoot motion

• Transfer from low gear to high gear during propulsion

• Angle and base of gait

• Abductory twist?

• Prominent extensor tendons (extensor substitution)

• Clawing of digits (flexor stabilisation)

Sagittal plane observations

Upper body

• Forwards or backwards tilt

• Symmetrical arm swing

Lower limb

• Position/timing of hip joint motion

• Position/timing of knee joint motion

• Position/timing of ankle joint motion

Foot

• Timing/amount of heel lift

• Timing/amount of midtarsal joint motion

• Timing/amount of first metatarsophalangeal joint motion

In clinical practice, observational analysis of gait is usually done after taking the history and carrying out a physical examination of the patient in order to evaluate the presence of any abnormal function that may be responsible for the patient’s presenting complaint. The subsequent more detailed static and non-weightbearing biomechanical evaluation can be guided to particular areas of interest by the gait analysis. Of importance at this stage of the clinical evaluation is a consistency between the observed gait and the findings of the biomechanical evaluation. For example, if a lot of transverse plane motion of the midfoot is observed in stance during the gait analysis, a similar increase in the transverse plane direction of motions at the subtalar and midtarsal joints should generally be observed.

There is a tendency in clinical practice to focus on frontal plane motion during the gait analysis, but motion in the transverse and sagittal planes is just as important to appreciate gait. This primarily occurs for several reasons. Most clinics only have long corridors available which facilitate the observation in the frontal plane but hinder sagittal plane observation. The traditional teaching of clinical biomechanics places great importance on frontal plane compensation for different pathomechanical entities, which encourages the use of observation of gait to assess frontal plane motion of the posterior aspect of the calcaneus. The observation of the calcaneus in the frontal plane is easy, but is not necessarily indicative of any abnormal or compensatory gait patterns. For example, any abnormal compensatory movement of the calcaneus in the frontal plane is entirely dependent on the range of motion of the joints of the rearfoot complex and the orientation of the assumed position of the subtalar joint axis. If the axis is more vertical than the assumed normal, there will be very little motion of the calcaneus in the frontal plane, with more in the transverse plane. If the axis is more horizontal, there will be more motion in the frontal plane, which may not be pathological. Observational gait analysis is also limited by the ability to observe transverse plane motions and the difficulty to observe and interpret motion in all three planes simultaneously, as well as the motion occurring simultaneously at several joints. In a clinical setting in patients with pathology, the observation of gait requires walking for some time, which can be tiring for the patients. The endurance of the patient needs to be considered.

There is no permanent record from observational gait analysis – no opportunity to review the data at a later date. The analysis is very dependent on the skill and experience of the observer. All the data are subjective and qualitative. When one observes an individual standing on both feet, it is impossible to predict whether the load (distribution of force) under both feet is equal. This highlights the fundamental drawback of observation of gait: you cannot observe forces and the eye can be easily deceived. Reliability studies on observational gait analysis show that it is somewhat unreliable (Brunnekreef et al 2005, Krebs et al 1985, Saleh & Murdoch 1985). Despite these limitations, observational gait analysis provides a good overall impression of gait and requires no equipment. Experienced observers use observational gait analysis to make critical judgements, assist in diagnosis and determine the outcomes of interventions such as foot orthoses.

Treadmill

One of the most debated areas of gait analysis is the length of walkway required to achieve ‘normal’ walking patterns: 4–6 m is considered the minimum, but 8–10 m is more appropriate. Some practitioners use treadmills rather than an overground walkway. This is for several reasons: to view running, allow use of video systems or due to a lack of clinical space. If a treadmill is used, one must ensure that the participant has every opportunity to adapt to treadmill walking before the analysis. This usually requires at least 15 minutes of walking on the treadmill. The more exposure to treadmills, the shorter the time recorded to acclimatise and perform consistently (Tollafield 1990). Clearly, older clients, children and clients with medical conditions are likely to tire more quickly. No matter how sophisticated the system is, participants must feel relaxed and comfortable when being observed. Most authorities now accept that in order to achieve this objective, clients should be allowed to walk at their own cadence rather than being artificially constrained by walking in time to a metronome or some other timing device.

For visual observation, treadmills facilitate closer inspection of the gait as well as easy observation of gait in the sagittal plane. In addition, treadmills are relatively inexpensive. There are subtle kinematic and kinetic differences between overground and treadmill gait (Riley et al 2006), however the principal consideration is that people should feel comfortable when using the treadmill.

Video

Video recording of gait for subsequent analysis (overground or on a treadmill) offers a different perspective than visual gait analysis. Observational gait analysis is limited by the high speed at which motions occur. It has been observed that events that happen faster than 83 ms (1/12 second) cannot be perceived by the human eye (Gage & Ounpuu 1989), so the use of slow-motion video and freeze-frame can enhance observational gait analysis. For example, some of the motions at the first metatarsophalangeal joint can be observed (Fig. 11.2). With good pause and slow-motion facilities the more subtle features of gait that would otherwise be missed can be observed. This will depend on the frequency of sampling: below 30 Hz may be insufficient, 50 Hz is an ideal for slow walking and 100 Hz will generally be required for running. If these sampling rates are not used, too much movement happens between each sampling frame to be useful for interpretation. Unfortunately, the standard frame rate for consumer-level video cameras is 25 Hz (PAL) and 30 Hz (NTSC). This means that the frame rate for such cameras makes it difficult to see fast-moving parts of the gait cycle: particularly around heel contact and heel and toe off. Some video software systems interpolate video (mathematically create a new video frame between two existing frames) to get around the low frame rate problem, with varying levels of success.