Chapter 13

1. Chapter 13 Gait and posture analysis

2. Overview • It is not clear whether gait is learned or is pre-programmed at the spinal cord level. However, once mastered, gait allows us to move around our environment in an efficient manner, requiring little in the way of conscious thought, at least in familiar surroundings.

3. The Gait Cycle • Walking involves the alternating action of the two lower extremities • The walking pattern is studied as a gait cycle • The gait cycle is defined as the interval of time between any of the repetitive events of walking. Such an event could include the point when the foot initially contacts the ground, to when the same foot contacts the ground again

4. The Gait Cycle • The gait cycle consists of two periods: stance and swing • The stance period • Constitutes approximately 60% of the gait cycle • Describes the entire time the foot is in contact with the ground and the limb is bearing weight • Begins with the initial contact of the foot on the ground, and concludes when the ipsilateral foot leaves the ground • The stance period takes about 0.6 sec during an average walking speed

5. The Gait Cycle • Swing period • Constitutes approximately 40% of the gait cycle • Describes the period when the foot is not in contact with the ground • Begins as the foot is lifted from the ground and ends with initial contact with the ipsilateral foot

6. Stance Period • Within the stance period, two tasks and four intervals are recognized • The two tasks include weight acceptance and single limb support • The four intervals include loading response, mid stance, terminal stance and pre-swing

7. Stance Period • Weight acceptance • The weight acceptance task occurs during the first 10% of the stance period • The loading response interval begins as one limb bears weight while the other leg begins to go through its swing period. This interval may be referred to as the initial double stance period and consists of the first 0-10% of the gait cycle

8. Stance Period • Single Leg Support • The middle 40% of the stance period is divided equally into mid stance and terminal stance • The mid stance interval representing the first half of the single limb support task, begins as one foot is lifted, and continues until the body weight is aligned over the forefoot • The terminal stance interval is the second half of the single limb support task. It begins when the heel of the weight bearing foot lifts off the ground and continues until the contralateral foot strikes the ground

9. Stance Period • Limb Advancement • Pre-swing. This interval begins with initial contact of the contralateral limb and ends with ipsilateral toe-off. As both feet are on the floor at the same time during this interval, double support occurs for the second time in the gait cycle.

10. Swing Period • Within the swing period, one task and four intervals are recognized • The task involves limb advancement • The four intervals include pre-swing, initial swing, mid-swing, and terminal swing

11. Swing Period • Limb Advancement • Pre-swing. In addition to representing the final portion of the stance period and single limb support task, the pre-swing interval is considered as part of the swing period • Initial swing. This interval begins with the lift of the foot from the floor and ends when the swinging foot is opposite the stance foot.

12. Swing Period • Limb Advancement • Mid-swing. This interval begins as the swinging limb is opposite the stance limb, and ends when the swinging limb is forward and the tibia is vertical • Terminal swing. This interval begins with a vertical tibia of the swing leg with respect to the floor, and ends the moment the foot strikes the floor

13. Gait parameters • Cadence • Cadence is defined as the number of separate steps taken in a certain time • Normal cadence is between 90 and 120 steps per minute • The cadence of women is usually 6-9 steps per minute slower than that of men • Cadence is also affected by age, with cadence decreasing from the age of 4 to the age of 7, and then again in advancing years

14. Gait parameters • Stride length • Step length is measured as the distance between the same point of one foot on successive footprints (ipsilateral to the contralateral foot fall). • Stride length, on the other hand, is the distance between successive points of foot-to-floor contact of the same foot • A stride is one full lower extremity cycle • Two step lengths added together make the stride length

15. Characteristics of Normal Gait • Gait involves the displacement of body weight in a desired direction utilizing a coordinated effort between the joints of the trunk and extremities and the muscles that control or produce these motions • Any interference that alters this relationship may result in a deviation or disturbance of the normal gait pattern

16. Normal Gait • Five priorities of normal gait: • Stability of the weight bearing foot throughout the stance period • Clearance of the non-weight bearing foot during the swing period • Appropriate pre-positioning (during terminal swing) of the foot for the next gait cycle • Adequate step length • Energy conservation

17. Center of Gravity (COG) • During the gait cycle, the COG is displaced both vertically and laterally

18. Joint Motions in Gait • Trunk and Upper Extremities • During the gait cycle: • The swing of the arms is out of phase with the legs • As the upper body moves forward, the trunk twists about a vertical axis • The thoracic spine and the pelvis rotate in opposite directions to each other to enhance stability and balance • The lumbar spine tends to rotate with the pelvis • The shoulders and trunk rotate out of phase with each other during the gait cycle

19. Joint Motions in Gait • Pelvis • For normal gait to occur, the pelvis must both rotate and tilt

20. Joint Motions in Gait • Sacroiliac Joint • As the right leg moves through the swing period, the position of the right innominate changes from one of extreme anterior rotation at the point of pre-swing to a position of posterior rotation at the point of initial contact • As the right extremity moves through the loading response to mid stance, the ilium on that side begins to convert from a posteriorly rotated position to a neutrally rotated position. From mid stance to terminal stance, the ilium rotates anteriorly, achieving maximum position at terminal stance

21. Joint Motions in Gait • Sacroiliac Joint • The sacrum rotates forward around a diagonal axis during the loading response, reaching its maximum position at mid stance (e.g., right rotation on a right oblique axis at right mid stance), and then begins to reverse itself during terminal stance

22. Joint Motions in Gait • Hip • Hip motion occurs in all three planes during the gait cycle • Knee • The knee flexes twice and extends twice during each gait cycle: once during weight bearing and once during non-weight bearing

23. Joint Motions in Gait • Foot and ankle • Ankle joint motion during the gait cycle occurs primarily in the sagittal plane • At initial contact with the ground the ankle is dorsiflexed • During the loading response interval, plantar flexion occurs at the talocrural joint, with pronation occurring at the subtalar joint • At the end of the mid stance interval, the talocrural joint is maximally dorsiflexed, and the subtalar joint begins to supinate • From the mid stance to the terminal stance interval the foot is in supination • Once the ankle is fully close-packed, the heel is lifted by a combination of passive force and contraction from the taut gastrocnemius, and the soleus

24. Muscle Actions in Gait • Spine and pelvis • During the swing period, the semispinalis, rotatores, multifidus, and external oblique muscles are active on the side toward which the pelvis rotates • The erector spinae and internal oblique abdominal muscles are active on the opposite side • The psoas major and quadratus lumborum help to support the pelvis on the side of the swinging limb, while the contralateral hip abductors also provide support

25. Muscle Actions in Gait • Knee • During the swing period, there is very little activity from the knee flexors • The knee extensors contract slightly at the end of the swing period prior to initial contact. During level walking the quadriceps achieve peak activity during the loading response interval (25% maximum voluntary contraction) and are relatively inactive by mid stance as the leg reaches the vertical position and ‘locks’, making quadriceps contraction unnecessary

26. Muscle Actions in Gait • Hip • During the early to mid portion of the swing phase, the iliopsoas is the prime mover with assistance from the rectus femoris, sartorius, gracilis, adductor longus, and possibly the tensor fascia latae, pectineus, and the short head of the biceps femoris during the initial swing interval • In terminal swing, there is no appreciable action of the hip flexors when ambulating on level ground. Instead the hamstrings and gluteus maximus are strongly active to decelerate hip flexion and knee extension

27. Muscle Actions in Gait • Hip • The adductor magnus muscle supports hip extension and also rotates the pelvis externally toward the forward leg • In mid stance, coronal plane muscle activity is greatest as the abductors stabilize the pelvis. The muscle activity initially is eccentric as the pelvis shifts laterally over the stance leg. The gluteus medius and minimus remain active in terminal stance for lateral pelvic stabilization

28. Muscle Actions in Gait • Knee • Hamstring involvement is also important to normal knee function. The co activation of the antagonist muscles about the knee during the loading response aid the ligaments in maintaining joint stability, by equalizing the articular surface pressure distribution, and controlling tibial translation.

29. Muscle Actions in Gait • Foot and ankle • During the beginning of the swing period, the tibialis anterior, extensor digitorum longus (EDL), extensor hallucis longus (EHL), and possibly the peroneus tertius contract concentrically with slight to moderate intensity tapering off during the middle of the swing period

30. Muscle Actions in Gait • Foot and ankle • At the point where the leg is perpendicular to the ground during the swing period, the tibialis anterior, EDL and EHL group of muscles contract concentrically to dorsiflex and invert the foot in preparation for the initial contact

31. Muscle Actions in Gait • Foot and ankle • Following initial contact, the anterior tibialis works eccentrically to lower the foot to the ground during the loading response interval • Calcaneal eversion is controlled by the eccentric activity of the posterior tibialis, and the anterior movement of the tibia and talus is limited by the eccentric action of the gastrocnemius and soleus muscle groups as the foot moves towards mid stance • Pronation occurs in the stance period to allow for shock absorption, ground terrain changes, and equilibrium

32. Muscle Actions in Gait • Foot and ankle • The triceps surae become active again from mid stance to the late stance period contracting eccentrically to control ankle dorsiflexion as the COG continues to move forward • In late stance period the Achilles tendon is stretched as the triceps surae contracts and the ankle dorsiflexes • At this point the heel rises off the ground and the action of the plantar flexors changes from one of eccentric contraction, to one of concentric contraction

33. Influences on Gait • Pain • Posture • Flexibility and the amount of available joint motion • Endurance - economy of mobility • Base of Support • Interlimb coordination • Leg-length • Gender • Pregnancy

34. Influences on Gait • Obesity • Age • Lateral and vertical displacement of the COG • Properly functioning reflexes • Vertical Ground Reaction Forces • Medial-Lateral Shear Forces • Anterior-Posterior Shear Forces

35. Specific Deviations of Individual Joints • Hip • Inadequate power • Inadequate or inappropriate range of motion • Malrotation

36. Specific Deviations of Individual Joints • Knee • The common problem at the knee during the stance period is excessive flexion. During the swing period, the most common error is due to inadequate motion

37. Specific Deviations of Individual Joints • Foot and ankle • There are three broad types of errors of the foot and ankle in the stance and swing periods: • Malrotation • Varus or valgus deformity • Abnormal muscle moments

38. Abnormal Gait Syndromes • In general gait deviations fall under four headings: • Those caused by weakness • Those caused by abnormal joint position or range of motion • Those caused by muscle contracture • Those caused by pain

39. Abnormal Gait Syndromes • Antalgic Gait • The antalgic gait pattern can result from numerous causes including joint inflammation or an injury to the muscles tendons and ligaments of the lower extremity • The antalgic gait is characterized by a decrease in the stance period on the involved side in an attempt to eliminate the weight from the involved leg and use of the injured body part as much as possible

40. Abnormal Gait Syndromes • Equinus Gait • Equinus gait (toe-walking), one of the more common abnormal patterns of gait of patients with spastic diplegia, is characterized by forefoot strike to initiate the cycle and premature plantar flexion in early stance to midstance

41. Abnormal Gait Syndromes • Gluteus maximus Gait • The gluteus maximus gait, which results from weakness of the gluteus maximus, is characterized by a posterior thrusting of the trunk at initial contact in an attempt to maintain hip extension of the stance leg • The hip extensor weakness also results in forward tilt of the pelvis, which eventually translates into a hyperlordosis of the spine to maintain posture

42. Abnormal Gait Syndromes • Quadriceps Gait • Quadriceps weakness can result from a peripheral nerve lesion (femoral), a spinal berve root lesion, from trauma, or from disease (muscular dystrophy) • Quadriceps weakness requires that forward motion be propagated by circumducting each leg. The patient leans the body toward the other side to balance the center of gravity, and the motion is repeated with each step

43. Abnormal Gait Syndromes • Spastic Gait • A spastic gait may result from either unilateral or bilateral upper motor neuron lesions • Spastic hemiplegic (hemiparetic) gait. This type of gait results from a unilateral upper motor neuron lesion and is frequently seen following a completed stroke • Spastic paraparetic gait. This type of gait results from bilateral upper motor neuron lesions (e.g., cervical myelopathy in adults and cerebral palsy in children)

44. Abnormal Gait Syndromes • Ataxic Gait • The ataxic gait is seen in two principal disorders: cerebellar disease (cerebellar ataxic gait) and posterior column disease (sensory ataxic gait)

45. Abnormal Gait Syndromes • Steppage Gait • This type of gait occurs in patients with a foot drop • A foot drop is the result of weakness or paralysis of the dorsiflexor muscles due to an injury to the muscles, their peripheral nerve supply, or the nerve roots supplying the muscles • The patient lifts the leg high enough to clear the flail foot off the floor by flexing excessively at the hip and knee, and then slaps the foot on the floor

46. Abnormal Gait Syndromes • Trendelenburg Gait • This type of gait is due to weakness of the hip abductors (gluteus medius and minimus) • The normal stabilizing affect of these muscles is lost and the patient demonstrates an excessive lateral list in which the trunk is thrust laterally in an attempt to keep the center of gravity over the stance leg

47. Abnormal Gait Syndromes • Parkinsonian Gait • The parkinsonian gait is characterized by a flexed and stooped posture with flexion of the neck, elbows, metacarpophalangeal joints, trunk, hips, and knees • The patient has difficulty initiating movements and walks with short steps with the feet barely clearing the ground. This results in a shuffling type of gait with rapid steps

48. Abnormal Gait Syndromes • Hysterical Gait • The hysterical gait is non-specific and bizarre • It does not conform to any specific organic pattern with the abnormality varying from moment to moment and from one examination to another • There may be ataxia, spasticity, inability to move, or other types of abnormality • The abnormality is often minimal or absent when the patient is unaware of being watched or when distracted

49. Posture • Good posture is a subjective term reflecting what the clinician believes to be correct based on ideal models. • Generally speaking muscles can be subdivided into: • Postural muscles • Phasic muscles

50. Posture • The ability to main correct posture is related to a number of factors, which includes but is not limited to: • Energy cost • Strength and flexibility • Structural deformities • Disease • Pain