SECTION ONE Clinical Observation by Gerard Malanga, MD and Joel A. DeLisa, MD Dr. Malanga is Director of Spine and Occupational Medicine at Kessler Institute for Rehabilitation and Assistant Professor of Physical Medicine and Rehabilitation at the University of Medicine and Dentistry-New Jersey Medical School. Dr. DeLisa is Professor and Chairman of the Department of Physical Medicine and Rehabilitation at the University of Medicine and Dentistry-New Jersey Medical School and is the President of Kessler Medical Rehabilitation Research and Education Corporation. INTRODUCTION within the gait cycle . This is diagrammatically repre- sented in Figure 1, by Verne T. Inman, MD, PhD. The ability to walk upright is a defining character- The stance phase is 60 percent of the gait cycle and istic of man. Gait is the manner in which walking is can be subdivided into double-leg and single-leg stance. performed and can be normal, antalgic, or unsteady. In double-leg stance, both feet are in contact with the Gait analysis can be assessed by various techniques but ground. At an average walking speed, it represents 10 is most commonly performed by clinical evaluation percent of the entire gait cycle, but decreases with incorporating the individual's history, physical examina- increased walking speed and ultimately disappears as tion, and functional assessment . Gait abnormalities can one begins to run . At slower walking velocities the be more precisely examined through the use of gait double-leg support times are greater . Single-leg stance laboratories. These laboratories utilize surface EMG comprises up to 40 percent of the normal gait cycle . The activity of muscles, force plates, and kinematic evalua- muscles that are active during the stance phase act to tion of the lower limbs . They are highly specialized prevent buckling of the support limb. These include the units that assess various gait abnormalities from indi- tibialis anterior, the quadriceps, the hamstrings, the hip viduals with neuromuscular disorders to high-level abductors, the gluteus maximus, and the erector spinae athletics . While some clinical impressions have been (1,4,5). shown to be incorrect by the use of gait lab technology, The swing phase is described when the limb is not the clinical evaluation still remains the essential compo- weight bearing and represents 40 percent of a single gait nent in determining the etiology and the treatment plan cycle. It is subdivided into three phases: initial swing for gait problems . A proper clinical evaluation should (acceleration), midswing, and terminal swing (decelera- always precede any gait lab assessment. tion). Acceleration occurs as the foot is lifted from the floor and, during this time, the swing leg is rapidly accelerated forward by hip and knee flexion along with Normal Gait ankle dorsiflexion . Midswing occurs when the accelerat- The determination of abnormal gait requires one to ing limb is aligned with the stance limb . Terminal swing first have an understanding of the basic physiology and then occurs as the decelerating leg prepares for contact biomechanics of normal gait (1,2,3) . The gait cycle is a with the floor and is controlled by the hamstring time interval or sequence of motion occurring from muscles. heelstrike to heelstrike of the same foot . The gait cycle has been broadly divided into two phases: stance phase Determinants of Gait and Energy Conservation and swing phase. These phases can then be further During gait, three main events occur in which subdivided and discussed in terms of percentage of each energy is consumed. This includes controlling forward 2 RRDS Gait Analysis in the Science of Rehabilitation RIGHT LEFT LEFT RIGHT RIGHT LEFT INITIAL PRE-SWING INITIAL PRE-SWING INITIAL PRE-SWING CONTACT CONTACT CONTACT ( I I Time, percent of cycle E I I I I I I I I I Double [04_ 11 R. Single support 1. Single support I support supportle sousupport I ! , I I I I I I 0% 115% 43% ep% 1dO% R. Stance phase I* R. Swing phase ---01 ► , 14--1. Swing phase --~f 1. Stance phase 40% 55% 85% 100% Figure 1. Time dimensions of the gait cycle. (Reprinted, with permission, from a chapter by V .T. Inman et al ., which appeared on page 26 of Human Walking, edited by Rose and Gamble and published by Williams & Wilkins, Baltimore, MD ; 1981.) movement during deceleration toward the end of swing With respect to lateral displacements : As weight is phase, shock absorption at heelstrike, and propulsion transferred from one leg to the other, there is shift of the during push off, when the center of gravity is propelled pelvis to the weight-bearing side . The oscillation of the up and forward (6,7) . Muscle activity used during the COM amounts to side-to-side displacement of approxi- gait cycle is noted in Table 1. mately 5 cm . The lateral limits are reached at mid- A human's center of mass (COM) is located just stance. anterior to the second sacral vertebra, midway between In his classic article, Inman describes the compo- both hip joints . The least amount of energy is required nents of gait (8). These are referred to as the six when a body moves along a straight line, with the COM determinants of gait (Table 2) . He describes several deviating neither up nor down, nor side to side. Such a mechanical factors that help to flatten the arc in the straight line would be possible in normal gait if man's vertical and horizontal (lateral) planes reducing dis- lower limbs terminated in wheels instead of feet . This placement of the body's COM and thereby reducing the obviously is not the case, thus, our COM deviates from energy expenditure. The net effect is a smooth, the straight line in vertical and lateral sinusoidal sinusoidal translation of the COM through space along a displacements. path that requires the least amount of energy. Any With respect to vertical displacement: the COM pathology that increases the vertical distance between goes through rhythmic upward and downward motion as the high and low points, increases the energy cost of it moves forward . The highest point occurs at ambulation. midstance, the lowest point occurs at time of double First determinant : pelvic rotation in the horizontal support. The average amount of vertical displacement in plane. This allows the swinging hip to move forward the adult male is approximately 5 cm . faster than the stance hip (1—3,8,9). Pelvic rotation 3 Section One: Clinical Observation Table 1. Primary muscular activity during the gait cycle. Muscular Activity Muscles Period Shock Absorbers Quadriceps Weight-Loading Dorsiflexors Stabilizers Gluteus Maximus, Medals, & Minimus Stance Phase Tensor Fascia Lata Erector Spinae Foot Lift Off Flexor Digitorum Longus Weight-Unloading Flexor Hallucis Longus Gastrocnemius Peroneus Longus and Brevis Soleus Tibialis Posterior Accelerators Adductor Longus and Magnus Weight-Unloading Iliopsoas Sartorius Foot Controllers Extensor Digitorum Longus Swing-Phase Extensor Hallucis Longus Tibialis Anterior Decelerators Gracilis Swing-Phase Semimembranosus mid-swing to initial-contact Semitendinosus Biceps Femoris Table 2. Determinants of Gait. Determinant COM Displacement Effect First Pelvic Rotation Decreased 4° of each side from a total Energy conservation saves the COM About the vertical axis, alternating to of 8° drop at its lowest point 6/16 inch the right and to the left relative to line Reduces the drop in COM during (elevates end or arc) of progression double limb support Second Pelvic Tilt Reduces the peak of COM during Energy conservation by shortening the At horizontal axis at midstance single limb support pendulum of the leg (3/16 inch) at the high part of arc (depresses summit arc) Third Knee flexion in stance High point of COM further reduced Energy conservation by decreasing rise by knee flexion in midstance of arc (7/16 inch) by walking over a bent knee (depresses summit arc) Fourth & Fifth Foot and ankle mechanism Combination of foot and ankle motion Flattens and slightly reverses arc of with knee motion smoothes the COM translation (decreased 3/16 inch) change in direction Sixth Lateral displacement of pelvis Must bring COM above support point Lateral displacement of the pelvis is to balance on one leg largely abolished by the presence of the tibial-femoral angle . There is a side-to-side sway of 1 .7 inch radius COM = Center of Mass 4 RRDS Gait Analysis in the Science of Rehabilitation occurs anteriorly on the swinging limb and posteriorly extension and a shorter stride length compared with during midstance. It is maximal just before heelstrike younger people (5). with a total motion of pelvic rotation of 3–5° to each The clinical evaluation of gait occurs within the side. Pelvic rotation also produces a longer stride length context of a detailed history and physical examination. for the same amount of hip flexion of the advancing leg The history may reveal complaints of pain, weakness, or and hip extension of the retreating leg . Thus, it allows instability . In addition, it is important to know the for longer steps without changing the COM displace- individual's past medical history to be aware of ment significantly. underlying neurologic or musculoskeletal problems . The Second determinant : pelvic tilt in the frontal plane. examination must include a detailed musculoskeletal As the pelvis on the swing leg is lowered, the hip and neurologic examination . It must address an evalua- abductors of the stance hip control pelvic tilt . During tion of the person's muscle strength, joint range of normal gait, the pelvis drops 4–5° away from the stance motion, tone, and proprioception . The musculoskeletal leg and toward the swing leg . This pelvic dip decreases examination should include, at a minimum, the joint horizontal displacement of the COM during single limb above and below the area of complaint.