Kinesiology 2 Fall2024 Lecture 2 Pathomechanics of the hip joint PDF

KARIM GHUIBA ‫هبيوغ ميرك‬ LECTURER OF PHYSICAL THERAPY CAIRO-GALALA UNIVERSITY DOCTOR OF PHYSICAL THERAPY NEW YORK, USA karim Ghuiba 10/9/2024  Kinesio...

KARIM GHUIBA ‫هبيوغ ميرك‬ LECTURER OF PHYSICAL THERAPY CAIRO-GALALA UNIVERSITY DOCTOR OF PHYSICAL THERAPY NEW YORK, USA karim Ghuiba 10/9/2024  Kinesiology 2 F a l l 2 0 2 4 T H E F U T U R E S T A R T S H E R E  G A L A L A U N I V E R S I T Y T H E F U T U R E S T A R T S H E R E T H E F U T U R E S T A R T S H E R E The one-joint hip flexors consist of the psoas major, iliacus, and psoas minor, although the latter does not actually cross the hip joint. Additional two-joint hip flexors include the rectus femoris, tensor fasciae latae, and sartorius. Although it has a smaller moment arm for flexion than some other hip flexors, its large physiological cross-sectional area (PCSA) makes it a strong hip flexor. The center of mass of the head, arms, and trunk (HAT) lies posterior to the flexion and extension axis of the hip joint, applying an extension moment to the hip. Contraction of the psoas major is able to produce a flexion moment to counteract the extension moment. The muscle is better aligned to apply significant compressive loads to the lumbar spine than to flex or extend it. This compressive load may be sufficient to assist in stabilization of the spine. The compressive loads applied by psoas major contractions also may explain why individuals with low back pain report pain with hip flexion activities. Effects of weakness: Weakness of the psoas major the strength of hip flexion. Such weakness could produce such as lifting a limb in and out of the bathtub and climbing stairs. Loss in muscle bulk, presumably accompanied by loss of strength, may contribute to the functional declines documented with age, such as diminished balance and difficulty in stair climbing. Effects of tightness: Tightness of the psoas major restricts hip extension range of motion (ROM). It may also limit trunk side-bending flexibility. In the upright posture, tightness of the psoas major is often manifested by increased lumbar extension, that is, by an excessive lumbar lordosis. This posture results from the pull on the lumbar vertebrae toward the femur and simultaneous compensation of backward-bending elsewhere in the spine for the individual to keep the eyes on the horizon. Iliacus: The iliacus is a large muscle with a PCSA equal to or greater than the PCSA of the psoas major. It is regarded with the psoas major as the primary hip flexor. Together they are known as the iliopsoas muscle. Like the psoas major, the iliacus exhibits EMG activity during sit-up and curl-up activities, presumably participating in the hip flexion component of these exercises. It also may provide some support at the hip in upright standing to prevent the HAT weight from hyperextending the hip. Effects of weakness: Weakness of the iliacus decreases hip flexion strength. The functional effects are similar to those with weakness of the psoas major. Although these muscles frequently are weak together, in some cases such as in a spinal cord lesion, it is possible for some of the psoas major to be spared while the iliacus is involved. The subject who lacks muscular cont rol at t he hip can st and unsupported by assuming a position of hip hyperextension so that the weight of the HAT generates an extension moment at the hip. By resting in maximum hyperextension, the individual can use the passive support of the ligaments to prevent additional backward bending. This is known as hanging on the ligaments. Effects of tightness: Tightness of the iliacus reduces hip extension ROM. In the standing position, tightness of the iliacus results in an anterior pelvic tilt that is accompanied by hyperextension of the lumbar spine, if available, for the individual to maintain vision of the horizon. Therefore, as seen with a tight psoas major, a tight iliacus frequently leads to an increased lumbar lordosis. If, however, the subject lacks hyperextension flexibility in the spine, tightness of the iliacus or psoas major can produce a forward lean and a flattened lumbar spine in upright posture. Psoas minor: The psoas minor usually is grouped with the hip flexors but has no attachment on the femur and, consequently, no direct action on the hip. It is more accurately described as a trunk muscle. It is reportedly absent in about 40% of the population. Even when present, its actions cannot be isolated from those of other muscles of the trunk. The psoas minor is considerably smaller and weaker than the psoas major Hip extensors: Gluteus Maximus: The gluteus maximus is a large muscle with a PCSA at least 30% greater than that of the iliopsoas. It forms most of the contour of the buttocks. The gluteus maximus is active during trunk hyperextension from the prone position. Ascending stairs elicits activity in the hamstrings and adductor magnus along with the gluteus maximus. Single-stance wall squats and mini-squats also elicit considerable electrical activity in the gluteus maximus. The gluteus maximus exhibits less activity during active extension from the flexed position and more activity during extension from the extended or hyperextended position. The gluteus maximus appears particularly suited to help fully extend or hyperextend the hip joint. Weakness: Weakness of the gluteus maximus results in decreased strength of hip extension and lateral rotation. A classic gait pattern resulting from gluteus maximus weakness, known as the gluteus maximus lurch. The lurch is a rapid hyperextension of the trunk prior to, and continuing through, heel contact on the side of the gluteus maximus weakness. It has been suggested that the backward “lurch” moves the center of mass of the HAT weight to a position posterior to the hip joint, thus eliminating the need for the gluteus maximus to extend the hip. However, it is also important to recognize that such a significant gait deviation is more likely a result of weakness of other hip extensors in addition to the gluteus maximus. Tightness: Tightness of the gluteus maximus limits hip ROM in flexion and medial rotation and, perhaps, adduction, although its effects in the frontal plane are more difficult to ascertain since it appears to be both an abductor and adductor. Athletes such as runners who have strongly developed gluteus maximus muscles can exhibit such tightness Hip abductors: Gluteus medius: The gluteus medius is an abductor of the hip. Some authors also report that it medially rotates the hip or that the anterior fibers medially rotate the hip and the posterior fibers laterally rotate the hip. Gluteus minimus: The gluteus minimus is another strong abductor of the hip, although its PCSA is substantially smaller than that of the gluteus medius. Like the gluteus medius, with the hip extended, its anterior portion is a medial rotator of the hip with a larger rotation moment arm than that of the gluteus medius, and its posterior portion is a lateral rotator. The gluteus minimus also is firmly attached to the hip joint capsule. This attachment may help protect the capsule from impingement by pulling it out of the way of the greater trochanter during active hip abduction. Functional role of the hip abductors: The broad proximal attachments of both the gluteus medius and gluteus minimus indicate that these muscles are quite strong and are likely to participate in functional activities that require considerable force. Although active abduction of the hip in an open chain is used in activities such as getting on and off a bicycle, the essential role of the abductor muscles occurs during closed chain activities such as walking and running. These activities of bipedal ambulation are characterized by intermittent periods of one-legged stance. G a i t During the time of single limb support, the weight of the opposite limb and that of the HAT (the HAT-L weight) exerts an adduction moment on the stance hip, tending to make the body fall onto the unsupported side and adducting the hip on the stance side. To hold the pelvis and the weight above it stable, the abductor muscles on the support side pull from their distal attachments on the femur to their proximal pelvic attachments. This pull, if strong enough, holds the pelvis level and prevents its dropping on the unsupported side. Similarly, the hip abductors provide proximal support to stabilize the femur and help maintain frontal plane alignment of the knee and foot within the lower extremity closed chain. Weakness of the gluteus medius and minimus Results in a significant decrease in abduction strength, since they are the primary abductors of the hip. The functional ramifications of such weakness are most apparent in weight-bearing activities, specifically in single- limb support. The functional problem occurs during stance on the side of the weakness. As single-limb support begins and the abductor muscles are too weak to hold the pelvis level, the HAT-L weight tends to cause the pelvis to drop on the unsupported side. Effects of tightness of the abductor muscles: Tightness of these muscles results in decreased ROM in adduction and, perhaps, in lateral rotation. Such tightness is found in individuals with arthritis whose position of comfort frequently includes hip flexion and abduction. The functional consequences of an abduction contracture are seen most often in upright posture and may include changes in pelvic alignment to maintain erect posture or in the positions of the other joints of the lower extremity to optimize the base of support Hip adductors: Pectineus: The actions of flexion and adduction by the pectineus are consistent with its location at the hip and are supported by analysis of its moment arms. Analysis of the rotation moment arm of the pectineus and EMG data suggest that the muscle also is active in medial rotation with other adductors. Adductor brevis: The adductor brevis has one of the largest adduction moment arms of the muscles of the thigh and appears capable of hip adduction with the hip in any position of flexion. EMG data reveal activity in the adductor brevis only during medial rotation. Moment arm analysis also supports a role only in medial rotation. Adductor longus: The adductor longus exhibits a consistent, albeit small, medial rotation moment arm. The muscle appears to play a more consistent role in hip flexion and adduction than in rotation. Adductor magnus: The adductor magnus rightfully bears the name “magnus,” since it is substantially larger than any other adductor muscle. So, being similar in size to the biceps femoris of the hamstring muscle group. Adductor brevis: Mechanical analysis reveals that the muscle possesses an adduction moment arm regardless of sagittal plane hip position. Open chain adduction appears to elicit consistent EMG activity of the adductor longus. Assessment of the muscle’s moment arm reveals that the muscle as a whole possesses an adduction moment arm. The middle and posterior segments have smaller adduction moment arms and only in portions of the hip flexion range. Functional role of the adductors of the hip: Most investigators agree on one important functional role of the adductors to stabilize the pelvis during weight shifting from one limb to the other. This role is seen during gait as the adductors contract during the transitions from stance to swing and swing to stance. The adductors also help stabilize the hip during squatting activities. In squatting to lift something from the floor, an individual typically has the hips slightly abducted Effects of weakness: Adductor weakness is not common but may result from an injury to the obturator nerve. Such injuries have been reported following surgeries such as laparoscopic or endoscopic prostatectomies and even rarely following vaginal deliveries. Symptoms include gait instability and an abducted gait in which the affected limb contacts the ground with the hip excessively abducted. Effects of tightness: Tightness of the adductors is relatively common and may result from adaptive changes in muscles that are not routinely stretched. Such tightness is likely in sedentary individuals or in individuals on bed rest who do not receive active or passive exercises. In addition, adductor muscles are commonly affected by central nervous system disorders resulting in spasticity. Scissors gait deformity. Lateral rotators of the hip: The lateral rotators of the hip include the piriformis, obturator internus, superior and inferior gemelli, quadratus femoris, and obturator externus. Group actions: Reveal that the roles of these deep muscles in rotation are more complex. Effects of weakness and tightness: The gluteus maximus remains the strongest of the lateral rotators, and therefore, discrete weakness of these small muscles may be hard to detect. Medial rotators of the hip: Unlike the other actions of the hip, there are no muscles at the hip whose primary and consistent action is medial rotation of the hip  G A L A L A U N I V E R S I T Y T H E F U T U R E S T A R T S H E R E T H E F U T U R E S T A R T S H E R E