POSTURESagar Naik, PT POSTURE Sagar Naik, PT Posture can be defined as the relative arrangement of different parts of the body with line of gravity. Static & Dynamic Posture: In static postures the body and its segments are aligned and maintained in certain positions. Eg – Standing, kneeling, lying, and sitting A dynamic posture refers to postures in which the body or its segments are moving. Eg – Walking, running, jumping, throwing, and lifting The study of any particular posture includes kinetic and kinematic analyses of all body segments. The erect posture allows persons to use their upper extremities for the performance of large and small motor tasks. When the upper extremities are engaged by the use of crutches, canes, or other assistive devices to maintain the erect posture, an important human attribute is either severely compromised or lost. Erect bipedal stance gives us freedom for the upper extremities, but in comparison with the quadrupedal posture, erect stance has certain disadvantages. Erect bipedal stance increases the work of the heart Places increased stress on the vertebral column, pelvis, and lower extremities Reduces stability In the quadruped posture the body weight is distributed between the upper and lower extremities. In human stance the body weight is borne exclusively by the two lower extremities. The human species base of support (BOS), defined by an area bounded posteriorly by the tips of the heels and anteriorly by a line joining the tips of the toes, is considerably smaller than the quadruped base. The human’s center of gravity (COG), which is sometimes referred to as the body’s center of mass, is located within the body approximately at the level of ph y sio 2 4a ll.. . POSTURE Sagar Naik, PT Postural Control: ph y sio 3 Although only a minimal amount of muscular activity is required to maintain a stable erect standing posture, the control of posture is complex and is a part of the body’s motor control system. Postural control, which can be either static or dynamic, refers to a person’s ability to maintain stability of the body segments in response to forces that threaten to disturb the body’s structural equilibrium. The ability to maintain stability in the erect standing posture is a skill that the central nervous system (CNS) learns using information from passive biomechanical elements, sensory systems, and muscles. The CNS interprets and organizes inputs from the various structures and systems and selects responses based on past experience and the goal of the response. Reactive (compensatory) responses occur as reactions to external forces that displace the body’s center of gravity. Proactive (anticipatory) responses occur in anticipation of internally generated destabilizing forces such as raising one’s arms to catch a ball or bending forward to tie one’s shoes. Goals & Basic Elements of Postural Control: The major goals of postural control in the erect position are To control the body’s orientation in space Maintain the body’s center of gravity over the base of support Stabilize the head with respect to the vertical so that the eye gaze is approximately oriented Maintenance and control of posture depends on the integrity of the CNS, visual system, vestibular system, and the musculoskeletal system. In addition, postural control depends on information from receptors located in 4a ll.. . the second sacral segment, a location that is relatively distant from the base of support. Despite the instability caused by a small base of support and a high center of gravity, maintaining stability in the static erect posture requires very little energy expenditure in the form of muscle contraction. The bones, joints, and ligaments are able to provide the major torques needed to counteract gravity and frequent changes in body position assist in producing circulatory return. Perturbation can be sensory or mechanical. A perturbation is any sudden change in conditions that displaces the body posture away from equilibrium. a person’s ability to maintain the erect posture may be affected by altered outputs such as the inability of the muscles to respond appropriately to signals from the CNS. ph y sio 4 4a ll. PT Absent or Altered Inputs & Outputs: When inputs ore altered or absent. A second level of input includes cues from the vestibular system and proprioceptive input from all body segments. Muscle Synergies: A normally functioning CNS selects the appropriate combination of muscles to complete the task based on an analysis of sensory inputs. Another instance in which inputs may be disturbed is following injury. These displacements may be caused either by movements of the body segments or of the entire body. The CNS must be able to detect and predict instability and must be able to respond to all of this input with appropriate output to maintain the equilibrium of the body. In addition to altered inputs. Altered or absent inputs may occur either in the absence of the normal gravitational force in weightless conditions during space flight. Variations in an individual’s past experience and customary patterns of muscle activity will also affect the response. Muscle activation is based primarily on input from the hip and trunk proprioceptors. . and the muscles must be able to respond with appropriate speeds and forces.POSTURE Sagar Naik. Altering of visual input such as might occur when one’s eyes are covered unexpectedly might cause a sensory perturbation. .. & ligaments) as well as on the soles of the feet. or when someone has decreased sensation in the lower extremities. Joints in the musculoskeletal system must have a range of motion (ROM) that is adequate for responding to specific tasks. and around the joints (in joint capsule. Mechanical perturbation is displacements that involve direct changes in the relationship of center of gravity to the base of support. One method of producing mechanical perturbations experimentally is by placing subjects on a movable platform. the control system must respond to incomplete or distorted data and thus the person’s posture may be altered and stability compromised. tendons. The muscles respond in an attempt to restore the line of gravity to a position within the base of support. These postural responses are referred to as either synergies or strategies. Bursts of muscle activity occur in the ankle dorsiflexors. . hip extensors. sio 5 4a ll. Forward motion of the platform results in a relative displacement of the line of gravity (LOG) posteriorly. The synergies are task specific and appear to vary with a number of factors including Amount and direction of motion of the supporting surface Location. Bursts of activity in the plantarflexors. The tibialis anterior contributes to the restoration of stability by pulling the tibia anteriorly (reverse muscle action) and hence the body forward so that the line of gravity remains or centers within the base of support.. Examples of fixed – support synergies are the ankle and hip synergy.POSTURE Sagar Naik. Backward motion of the platform results in a relative displacement of the line of gravity anteriorly. magnitude. respectively. Stability is regained through movements of parts of the body but the feet remain fixed on the base of support. The muscles respond in an attempt to restore the line of gravity to a position within the base of support. abdominal muscles. Synergies are centrally organized patterns of muscle activity that occur in response to perturbation of standing postures. and neck flexors. The postural responses to perturbations are reactive or compensatory responses in that they are involuntary reactions. PT ph y Fixed – Support Synergies: Fixed – support synergies are patterns of muscle activity in which the base of support remains fixed during the perturbation and recovery of equilibrium. and velocity of the perturbing force Initial posture of the individual at the time of the perturbation . The ankle synergy consists of discrete bursts of muscle activity on either the anterior or posterior aspects of the body that occur in a distal-to-proximal pattern in response to forward and backward movements of the supporting platform. hip flexors. trunk extensors. and neck extensors are used to restore the line of gravity over the base of support. In change – in – support strategy. . Fixed – support hip synergy may be used primarily in situations where change – in – support strategies (stepping or grasping synergies) are not available. the younger subjects have a tendency to take only one step. Stepping and grasping differ from fixed – support synergies because stepping/grasping moves or enlarges the body’s base of support so that it remains under the body’s center of gravity. whereas the elderly subjects have a tendency to take multiple steps that are shorter and of less height than their younger counterparts. no differences are apparent in the speed at which the young and elderly initiate the change – in – support strategy. Head strategies are used to maintain the head during sustained movement of the body.. backward or sidewise) and grasping (using one’s hands to grab a bar or other fixed support) in response to movements of the platform. Change – in – support synergies are the only synergies that are successful in maintaining stability in the instance of a large perturbation. such as walking. . Two strategies for maintaining the vertical stability of the head are as follows: Head Stabilization in Space (HSS) Head Stabilization on Trunk (HST) 4a ll. Change – in – support strategies are common responses to perturbations among both the young and the old. Head Stabilizing Strategies: Two head stabilizing strategies are described which differ from reactive strategies because head stabilizing strategies occur in anticipation of the initiation of internally generated forces. Previously it was thought that the stepping synergy was used only as a last resort. PT ph y sio 6 Change – In – Support Strategies: The change – in – support strategies include stepping (forward. being initiated when ankle and hip strategies were insufficient to bring and maintain the center of gravity over the base of support. The hip synergy consists of discrete bursts of muscle activity on the side of the body opposite to the ankle pattern in a proximal-to-distal pattern of activation.POSTURE Sagar Naik. However. running. and jogging. The external and internal forces must be balanced and the sum of all the forces and torques acting on the body and its segments must be equal to zero for the body to be in equilibrium. The body attempts to attain and maintain a state of equilibrium in erect standing with minimum of energy expenditure as it attempts to keep the body’s center of gravity over the base of support and the head in a position that permits gaze to be appropriately oriented. In erect standing posture the body undergoes a constant swaying motion called postural sway or sway envelope. gravity. The head stabilization on trunk is one in which the head and trunk move as a single unit. ll. 4a The external forces that will be considered are inertia. joint capsules. The extent of the sway envelope for a normal individual standing with 4 inches between the feet can be as large as 12° in the sagittal plane and 16° in the frontal plane. The internal forces are produced by muscle activity and passive tension in ligaments. The anticipatory adjustments of head position are independent of trunk motion.. Gravitational forces act downward from the body’s center of gravity. PT Kinetics & Kinematics of Posture: ph y sio 7 Inertial & Gravitational Forces: Inertial forces are ignored in static postures because little or no acceleration is occurring except during postural sway. and other soft tissue structures. The head stabilization in space is a modification of head position in anticipation of displacements of the body’s center of gravity. . the line of gravity falls outside the base of support during a large portion of the activity. Inertial forces must be considered in postural analysis of all dynamic postures such as walking.POSTURE Sagar Naik. In dynamic postures such as walking and running. and ground reaction forces (GRFs). . In the static erect standing posture the vertical projection of the body’s center of gravity (the line of gravity) falls within the base of support. The line of gravity must fall within the base of support to maintain equilibrium in the static erect posture. tendons. . This force is known as the ground reaction force (GRF). The point of application of the ground reaction force vector is at the body’s center of pressure (COP). the ground pushes back on the body. The center of pressure is the theoretical point where the force is considered to act. body segments are aligned so that the torques and stresses on body segments are minimized and standing can be maintained with a minimal amount of energy expenditure. PT Ground Reaction Forces: Whenever the body contacts the ground. The effect of forces on the body segments in the sagittal plane is determined by the location of the line of gravity relative to the axis of motion of body segments. one of the two horizontal forces is in a medial-lateral direction. In an ideal erect posture. whereas the other horizontal force is in an anterior. The coincident action lines formed by the ground reaction force vector and the line of gravity serve as a reference for the analysis of the effects of these forces on the body segments. 8 ph y Sagittal Plane: sio Coincident Action Lines: 4a ll. which is located in the foot in unilateral stance and between the feet in bilateral stance. although the body surface that is in contact with the ground may have forces acting over a large portion of its surface area. The path of the center of pressure that defines the extent of the sway envelope.posterior direction along the ground The composite or resultant ground reaction force vector (GRFV) is equal in magnitude but opposite in direction to the gravitational force in the erect static standing posture. . The ground reaction force vector and line of gravity have coincident action lines in the static erect posture.POSTURE Sagar Naik.. Ground reaction force is a composite (resultant) force typically described as having three components: A vertical component force Two force components directed horizontally. The ground reaction force vector indicates the magnitude and direction of loading applied to the foot. or midway between dorsiflexion and plantarflexion. the torque will tend to cause posterior motion of the proximal segment of the body supported by that joint (Extension). ll.POSTURE Sagar Naik. This places the line of gravity just anterior to the knee joint axis. the torque will tend to cause anterior motion of the proximal segment of the body supported by that joint (Flexion).. If the gravity line falls posterior to the joint axis. anterior to the ankle joint axis. If the gravity line is located anterior to the joint axis. a gravitational torque is created. The knee joint is in full extension and the line of gravity passes anterior to the midline of the knee and posterior to the patella. The direction of the gravitational moment of the force depends on the location of the gravity line relative to a particular joint axis. Tibialis anterior. The line of gravity falls slightly anterior to the lateral malleolus and. 9 ph y Knee: sio 4a When line of gravity passes directly through a joint axis. PT Lateral View – Optimal Alignment in Sagittal Plane: Ankle: In the optimal erect posture the ankle joint is in the neutral position. therefore. The anterior position of the line of gravity relative to the ankle joint axis creates a dorsiflexion moment. This torque will cause rotation of the superimposed body segments around that joint axis unless a counterbalancing torque opposes the gravitational torque. tibialis posterior and peroneals provide transverse stability in the foot during postural sway. The magnitude of the gravitational moment of the force increases as the distance between the line of gravity and the joint axis increases. . If line of gravity passes at a distance from the axis. no gravitational torque is created around that joint. . The soleus muscle acting in reverse action exerts a posterior pull on the tibia and is able to oppose the dorsiflexion moment. Muscle activity of the plantarflexors is necessary to prevent forward motion of the tibia. hip is in a neutral position and the pelvis is level with no anterior or posterior tilt. Gravity. Anterior tilting of the sacrum increases the lumbosacral angle and results in an increase in the shearing stress at the lumbosacral joint and may result in an increase in the anterior lumbar convexity in standing. . a small amount of activity has been found in the hamstrings. hip hyperextension ultimately would be checked by passive tension in the ilifemoral. and ischifemoral ligaments. In a level pelvis position. therefore. The relaxed standing posture does not require any muscle activity at the hip but causes an increase in the tension stresses on the anterior hip ligaments. creates a very slight extension moment at L5 to S1 that is opposed by the anterior longitudinal ligament. The anterior location of gravitational line relative to the knee joint axis creates an extension moment. through the greater trochanter.. The posterior location of the gravitational line relative to the hip joint axis creates an extension moment at the hip that tends to rotate the pelvis posteriorly on the femoral heads. 4a ll. Passive tension in the posterior joint capsule and associated ligaments is sufficient to balance the gravitational moment and prevent hyperextension.POSTURE Sagar Naik. Iliopsoas is acting to create a balancing flexion moment at the hip. Lumbosacral and Sacroiliac Joints: The optimal lumbosacral angle is about 30°. Little or no muscle activity is required to maintain the knee in extension in the optimal erect posture. In this optimal position. If the gravitational extension moment at the hip is allowed to act without muscular balance. In the ideal posture the line of gravity passes through the body of the 5th lumbar vertebra and close to the axis of rotation of the lumbosacral joint. . However. and the lines connecting the anterior superior iliac and posterior superior iliac spines are horizontal. the line of gravity passes slightly posterior to the axis of the hip joint. PT Hip and Pelvis: ph y sio 10 In optimal posture. lines connecting the symphysis pubis and the anterior superior iliac spines are vertical. pubofemoral. as in so-called relaxed standing posture. the stress on the supporting structures would be greatest in the thoracic area. tension in the anterior longitudinal ligament and passive tension in the trunk flexors apparently is sufficient to balance the gravitational extension moment. posterior to the coronal suture and through the odontoid process. sio 11 4a ll. The line of gravity relative to the head passes through the external auditory meatus. When the sacrum is in optimal position. the line of gravity will pass through the midline of the trunk.POSTURE Sagar Naik. So logissimus dorsi. . Stress in the lumbar and cervical regions would be comparatively less because the line of gravity falls close to or through the joint axes of these regions. The gravitational moment that is created at sacroiliac joints tends to cause the anterior superior portion of the sacrum to rotate anteriorly and inferiorly while the posterior inferior portion tends to move posteriorly and superiorly. Tension in the sacrospinous and sacrotuberous ligaments counterbalances the gravitational torque and prevents the inferior portion of the sacrum from moving posteriorly. In this instance. rotators. The superior portion of the sacrum is kept from thrust anteriorly by the sacroiliac ligaments. Ligamentous structures and passive muscle tension are unable to provide enough force to oppose all gravitational moments acting around the joint axes of the vertebral column. PT Vertebral Column: ph y Head: When the vertebral curves are in optimal alignment. and neck extensor muscles have to work to produce the counterbalanced force. where minimal muscle activity appears to occur. The line of gravity passes through the bodies of the lumbar and cervical vertebrae and anterior to the thoracic vertebrae in the optimal posture. the line of gravity passes slightly anterior to sacroiliac joints.. In lumbar region. where the line of gravity would fall at a distance from the vertebrae. . the joint surfaces become susceptible to early degenerative changes. which tends to tilt the head forward. . . Postures that represent an attempt to either improve function or normalize appearance are called compensatory postures. Shortening of the ligaments will limit normal ROM. and by activity of the capital extensors. tectorial membrane. Prolonged weight-bearing stresses on the joint surfaces increase cartilage deformation and may interfere with the nutrition of the cartilage. Changes from optimal alignment increase stress or increase force per unit area on body structures. The gravitational moment. Muscles may lose sarcomeres if held in shortened positions for extended periods. the body structures may be altered. Such adaptive shortening may accentuate and perpetuate the abnormal posture. and posterior fibres of the annulus pulposus. If stresses are maintained over long period of time.. is counterbalanced by tension in the ligamentum nuchae. as well as prevent full ROM from occurring. PT Lateral View – Deviations from Optimal Alignment: ph y Minimizing energy expenditure and stress on supporting structures is one of the primary goals of any posture. sio 12 4a ll. Postural problems may originate in any part of the body and cause increased stresses and strains in throughout the musculoskeletal system. Any change in position or malalignment of one body segment will cause changes to occur in adjacent segments as well as changes in other segments as the body seeks to adjust or compensate for the malalignment. the line of gravity falls slightly anterior to the transverse (coronal) axis of rotation for flexion and extension of the head and creates a flexion moment. As a result. posterior aspect of the zygapophyseal joint capsules. Muscles may add sarcomeres if maintained in a lengthened position and as a consequence the muscle’s length-tension relationship will be altered. whereas stretching of ligamentous structures will reduce the ligament’s ability to provide sufficient tension to stabilize and protect the joints.POSTURE Sagar Naik. Therefore. Sometimes the proximal phalanx may subluxate dorsally on the metatarsal head. The flexor muscles are stretched over the metatarsophalangeal (MTP) joint and shortened over the interphalangeal (IP) joint. The extensor muscles are shortened over the metatarsophalangeal (MTP) joint and stretched over the interphalangeal (IP) joint. Callosities (painless thickening of epidermis) may be found on the superior surface of the proximal interphalangeal (PIP) joints over the heads of the 1st phalanges as a result of pressure from shoes or on the tips of the distal phalanges because of abnormal weight bearing. . the intrinsic and extrinsic toe flexors acting unopposed will buckle the proximal (PIP) and distal (DIP) interphalangeal joints and cause a hammer toe deformity. A callus may develop on the dorsal aspects of the flexed phalanges. PT Foot and Toes: Claw Toes: Claw toes is a deformity of the toes characterized by hyperextension of the metatarsophalangeal joint (MTP) combined with flexion of the proximal (PIP) and distal (DIP) interphalangeal joints. . sio 13 4a ll. and hyperextension of distal interphalangeal (DIP) joint.POSTURE Sagar Naik. flexion of the proximal interphalangeal (PIP) joint. Etiologies for this condition are as follows: Restrictive effect of shoes A cavus – type foot Muscular imbalance Ineffectiveness of intrinsic foot muscles Neuromuscular disorders Age–related deficiencies in the plantar structures ph y Hammer Toe: Hammer toe is described as a deformity characterized by hyperextension of the metatarsophalangeal (MTP) joint.. If the long and short toe extensors and lumbricales are selectively paralyzed. the line of gravity will fall anterior to the ankle joint axes. 4a ll. The length-tension relationship of the anterior and posterior muscles also may be altered and the muscles may not be able to provide the force necessary to provide adequate joint stability and mobility. the line of gravity will fall anterior to the hip joint axes. The increase in quadriceps muscle activity subjects the tibiofemoral and patellofemoral joints to greater than normal compressive forces. ph y sio 14 Hyperextended Knee Posture (Genu Recurvatum): The hyperextended knee posture is one in which the line of gravity is located considerably anterior to the knee joint axis. At the ankle. Activity of the hip extensors may be necessary to balance the gravitational flexion moment acting around hip.. The additional muscle activity subjects the hip and ankle joints to greater than normal compression stress. A continual adoption of the hyperextended knee posture is likely to result in adaptive lengthening of the posterior capsule. The anterior joint surfaces on the femoral condyles and anterior portion of the tibial plateaus are subject to degenerative changes of the cartilaginous joint surfaces. At the hip. Because knee flexion in upright stance is accompanied by hip flexion and ankle dorsiflexion. Thus. PT Knee: Flexed Knee Posture: In the flexed knee standing posture the line of gravity falls posterior to the knee joint axes. the location of the line of gravity also will be altered in relation to these joint axes.POSTURE Sagar Naik. the increased muscle activity would appear to substantially increase the energy requirements for stance. Increase soleus muscle activity may be required to counteract the increased gravitational dorsiflexion moment at the ankle. . . The posterior location of the line of gravity creates a flexion moment at the knees that must be balanced by activity of the quadriceps muscles to maintain the erect position. The anterior location of the line of gravity causes an increase in the gravitational extensor moment acting at the knee. which tends to increase the hyperextension deviation and put the posterior joint capsule under considerable tension stress. is at a greater distance from the lumbar joint axes than is optimal and the extension moment in the lumbar spine is increased. ph y Excessive Anterior Pelvic Tilt: In posture in which the pelvis is excessively tilted anteriorly.. sio Vertebral Column: 15 Lordosis: The term lordosis refers to an abnormal increase in the normal anterior convexities in either the cervical or lumbar regions of the vertebral column. the lower lumbar vertebrae are forced anteriorly. the anterior convexity of the cervical curve increases to bring the head back over the sacrum.POSTURE Sagar Naik. . The upper lumbar vertebrae move posteriorly to keep the head over the sacrum. thereby increasing the lumbar anterior convexity (lordotic curve). therefore. A greater diffusion of nutrients into the anterior compared to the posterior portion of the disc occurs in the optimal erect posture. In optimal posture the lumbar discs are subject to anterior tension and posterior compression in erect standing. Increases in the anterior convexity of the lumbar curve during erect standing increases the compressive forces on the posterior annuli and may adversely affect the nutrition of the posterior portion of the intervertebral discs. PT Hyperextension at the knee is usually caused by limited dorsiflexion at the ankle or a fixed plantarflexion position of the foot and ankle called equinus. The posterior convexity of the thoracic curve increases and become kyphotic to balance the lordotic lumbar curve and maintain the head over the sacrum. Similarly. It may also be the result of habits formed in childhood in which the child or adolescent stands with hips and knees hyperextended. The line of gravity. Pelvis: . Also excessive compressive forces may be applied to the zygapophyseal joints. 4a ll. An increase in the lumbar curve may be accompanied by a compensatory increase in both the anterior convexity of the cervical curve and in the posterior convexity of the thoracic curve. which bends forward causing an increase in the posterior convexity of the thoracic area (hump) and an increase in compression on the anterior aspect of the vertebral bodies. The anterior aspect of the bodies of a series of vertebrae collapse due to osteoporotic weakening. The vertebral body collapse causes an immediate lack of anterior support for the vertebral column. which causes vertebral fractures. Diseases such as tuberculosis or ankylosing spondylosis also may cause increases in the posterior convexity of the thoracic region. . Eg – 1) Gibbus or humpback deformity may occur as a result of tuberculosis. Sometimes kyphosis may develop as a compensation for an increase in the lumbar lordosis or the kyphosis may also develop as a result of poor postural habits. 4a ll. Forward Head Posture: A forward head posture is one in which the head is positioned anteriorly at an increased distance from the line of gravity and the normal anterior cervical convexity is also increased with the apex of the lordotic curve is considerable distance from the line of gravity compared to optimal posture. PT ph y sio Head: 16 Kyphosis: The term kyphosis refers to an abnormal increase in the normal posterior convexity of the thoracic vertebral column. The constant assumption of a forward head posture causes unrelieved increased compression on the posterior zygapophyseal joints and posterior portions of the intervertebral discs and narrowing of the intervertebral foramina in the lordotic areas of the cervical region. which forms a sharp posterior angulation in the upper thoracic vertebral column. The cervical extensor muscles may become ischemic because of the constant isometric contraction required to maintain the head in its forward position. Gibbus or humpback deformity is easily recognized by the Gibbus (hump). ..POSTURE Sagar Naik. 2) Dowager’s hump is another easily recognizable kyphotic condition that is found most often in postmenopausal women who have osteoporosis. a thoracic kyphosis may develop. The gravitational torques acting on one side of the body are opposed by equal torques acting on the other side of the body. and the gravitational line transects the central portion of the vertebral bodies. 4a ll. The eyes. In addition. the thoracic cavity may be diminished. such as bilateral knock knee (genu valgum). Symmetrical postural deviations. The joint axes of the hip. Anterior-Posterior View – Deviations from Optimal Alignment: Any asymmetry of body segments caused either by movement of a body segment or by a unilateral postural deviation will disturb optimal muscular and ligamentous balance. In forward head posture the scapulae may rotate medially. The waist angles and gluteal folds should be equal and the anterior superior iliac spines (ASIS) and posterior superior iliac spines (PSIS) should lie on a parallel line with the ground as well as being equidistant from the line of gravity. and shoulders should be level. PT Anterior–Posterior View – Optimal Alignment: ph y sio 17 In an anterior view the line of gravity bisects the body into two symmetrical halves. clavicles. When postural alignment is optimal. cause an abnormal distribution of weight bearing or compressive forces on one side of a joint and increased tensile forces on the other side. that disturb the optimal vertical alignment of body segments. The head is straight with no tilting or rotation evident. vital capacity can be reduced. the structure of the temporomandibular joint may become altered by the forward head posture and as a result the joint’s function may be disturbed. . . In posterior view the inferior angles of the scapulae should be parallel and equidistant from the line of gravity.POSTURE Sagar Naik. knee. little or no muscle activity is required to maintain media-lateral stability.. and ankle are equidistant from the line of gravity. The posterior aspect of the zygapophyseal joint capsules may become adaptively shortened and the narrowed intervertebral foramen may cause nerve root compression. and overall body height may be shortened. In either the rigid or flexible type of pes planus. especially at the 2nd metatarsal. Pes Cavus: A high medial longitudinal arch of the foot is called pes cavus. the talar head is displaced anteriorly. medially. PT The increased gravitational torques that may occur require increased muscular activity and cause ligamentous stress. tension in the plantar calcaneonavicular (spring) ligament and lengthening of the tibialis posterior muscle. the arch is reduced during normal weight bearing situations. which is characterized by a reduced or absent arch. The displacement of the talus causes depression of the navicular. Flatfoot. Foot and Toes: Pes Planus (Flatfoot): Normally the plumb line should lie equidistant from the malleoli. it is possible that a common foot problem known as pes planus. In this the medial longitudinal arch is absent in non-weight bearing. Weight bearing pronation in the erect standing posture also causes medial rotation of the tibia and may affect knee function. may be either rigid or flexible. and normal weight bearing situations. The rigid form of flatfoot interferes with push-off during walking because the foot is unable to assume the supinated position and become a rigid lever for push-off in gait. It also may result in increased weight bearing on the 2nd through 4th metatarsal heads with subsequent plantar callus formation. and inferiorly. In flexible flatfoot. but reappears during toe standing or non-weight bearing situations.POSTURE Sagar Naik. may be present. . and the malleoli should appear to be of equal size and directly opposite from one another. The pronated flatfoot results in a relatively overmobile foot that may require muscular contraction to support the osteoligamentous arches during standing.. or flatfoot. When one malleolus appears more prominent or lower than the other and calcaneal eversion is present. toe standing. 18 ph y sio 4a ll. A rigid flatfoot is a structural deformity that may be hereditary. . The patella may be laterally displaced and therefore predisposed to subluxation.POSTURE Sagar Naik. Flexor muscles are stretched over the metatarsophalangeal joints and shortened over the proximal interphalangeal joints. the cavus foot is unable to adapt to the supporting surface because the subtalar and transverse tarsal joints tend to be near or the locked supinated position. which leads to a hypermobile first ray. The mot common cause of hallux valgus is abnormal pronation in combination with forefoot adducts. and the lateral structures are subjected to abnormal compressive stress. In walking. Hallux Valgus: Hallux valgus is a fairly common deformity in which there is a medial deviation of the 1st metatarsal at the tarsometatarsal joint and a lateral deviation of the phalanges at the metatarsophalangeal joint. The foot also is affected as the gravitational torque acting on the foot in genu valgum tends to produce pronation of the foot with an 4a ll. The extensor muscles are shortened over the metatarsophalangeal joints and stretched over the proximal interphalangeal joints. If genu valgum exceeds 30° and persists beyond 8 years of age structural changes may occur. . ph y sio Knee: 19 Genu Valgum (Knock Knees): In genu valgum the mechanical axes of the lower extremities are displaced laterally. The combination of excess bone and bunion formation and possible metatarsophalangeal dislocation not only enlarge the joint but also are a source of pain and may require surgical intervention.. As a result of the increased torque acting around the knee. bony overgrowth may occur on the medial aspect of the joint in an attempt by the body to increase the joint surface area. PT The weight in pes cavus is borne on the lateral borders of the foot and the lateral ligaments and the peroneus longus muscle may be stretched. The bursa on the medial aspect of the 1st metatarsal head may become inflamed and form bunion in response to an increase in contact forces between the shoe and the side of the 1st metatarsophalangeal joint. In addition. the medial knee joint structures are subjected to abnormal tensile or distraction stress. . Some of the more commonly suggested cause of genu varum are vitamin D deficiency.POSTURE Sagar Naik. This altered patella position may be present in one or both knees and may by a sign of increased medial femoral torsion or medial tibial rotation. and lumbar spine contralateral rotation.. lateral tibial torsion. . Cortical thickening on the medial concavity of both the femur and tibia may be present as a result of the increased compressive forces and the patellae may be displaced medially. The Q angle may be increased in this condition and patella tracking may be adversely affected. laterally displaced position of the patella in which the patella faces upward and outward. Physiologic bowing is symmetrical and involves both the femur and the tibia. Grasshopper eyes patella leads to abnormal patellar tracking and a decrease in the stability of the patella. ph y sio 20 4a ll. Genu Varum (Bow Legs): Genu varum is a condition in which the knees are widely separated when the feet are together and malleoli are touching. osteochondritis. PT accompanying stress on the medial longitudinal arch and its supporting structures as well as abnormal weight bearing on the posterior medial aspect of the calcaneus. Squinting or Cross-Eyed Patella: Squinting or cross-eyed patella (in-facing patella) is a tilted/rotated position of the patella in which the superior medial pole of the patella faces medially and the inferior pole points laterally. The medially rotated position of the patella is due to either femoral retroversion or lateral tibial torsion. An abnormally long patella ligament may be responsible for the higher than normal position of the patella (patella alta). lateral patellar subluxation. Grasshopper Eyes Patella: Grasshopper eyes patella refers to a high. Additional related changes may include flatfoot. . or epiphyseal injury. renal rickets. PT Vertebral Column: Scoliosis: Normally. These curves involve changes in the structure of the vertebral bodies. and directly through the gluteal cleft. the superior segment is named first. when viewed from the posterior aspect. Asymmetrical growth and development of the vertebral bodies leads to wedging of the vertebrae. The line of gravity falls through the midline of the occiput. In an optimal posture the vertebral structures. ph y sio 21 4a ll. These curves are the result of correctable imbalances such as leg length discrepancy or muscle spasm. the curve is designated as a left cervical scoliosis. left lumbar scoliosis. The lateral bending will be accompanied by rotation of the vertebrae because lateral flexion and rotation are coupled motions below the level of the 2nd cervical vertebra. . Adolescent idiopathic scoliosis curves are defined as structural curves. A lateral curvature of the vertebral column that is convex to the right in the thoracic region and convex to the left in the lumbar region is named as right thoracic. If more than one region of the vertebral column is involved. and muscles are able to maintain the column in vertical alignment with little stress or energy expenditure. intervertebral discs. through the spinous processes of all vertebrae.. the vertebral column is vertically aligned and perfectly bisected by the line of gravity and the structures on either side of the column are symmetrical. transverse and spinous processes. . and muscles. Consistent lateral deviations of a series of vertebrae from the line of gravity in one or more regions of the spine may indicate the presence of a lateral spinal curvature called scoliosis. If one or more of the medial-lateral structures fails to provide adequate support.POSTURE Sagar Naik. If the curve is convex to the left in the cervical area. The curves in scoliosis are named according to the direction of the convexity and the location of the curve. ligaments. Nonstructural scoliosis curves are called functional curves in that they can be reversed if the cause of the curve is correlated and structural changes are not present. ligaments. the column will bend to the side.