hip jt 1-1.pptx.PDF

Biomechanics of the hip joint Asmaa Abd El Rhman Ahmed Physical therapy lecture Suez University objectives At the end of the lecture all should know about 1- Kinematics a) structure of the hip joint - bony articulation angles within the hip joint - capsule of the hip joint...

Biomechanics of the hip joint Asmaa Abd El Rhman Ahmed Physical therapy lecture Suez University objectives At the end of the lecture all should know about 1- Kinematics a) structure of the hip joint - bony articulation angles within the hip joint - capsule of the hip joint -Ligaments of the hip joint Bony articulation The hip joint is a synovial ball and socket joint Formed by the femoral head and the acetabulum Do the hips serve as “base” joints for the lower extremities, or do they serve as basilar joints for the entire superimposed pelvis and trunk? The hips serve both roles. Pathology or trauma affecting the hips typically causes a wide range of functional limitations, including difficulty in walking, dressing, driving a car, lifting and carrying loads, and climbing stairs. Hip disease and injury are frequent among the very young and the elderly. An abnormally formed hip in an infant may be prone to dislocation. The hip in the aged adult is vulnerable to degenerative joint disease. Increased severity of osteoporosis coupled with increased risk of falling also predisposes the elderly to a higher incidence of hip fracture. pelvic bone is the union of three bones: the ilium, pubis, and ischium. The right and left pelvic bone connect with each other anteriorly at the pubic symphysis and posteriorly at the sacrum. Function of pelvic bone Three important and very different functions. 1. First, the pelvis serves as a common attachment point for many muscles of the lower extremity and the trunk. 2. The pelvis also transmits the weight of the upper body and trunk either to the ischial tuberosities during sitting or to the lower extremities during standing and walking. 3. Last, with the aid of the muscles and connective tissues of the pelvic floor, the pelvis supports the organs involved with bowel, bladder, and reproductive functions.  ACETABULUM Located just above the obturator foramen is the large cup-shaped acetabulum. The acetabulum forms the socket of the hip. The acetabulum Receives the femoral head and lies on the lateral aspect of the hip bone It is directed Laterally, Inferiorly Anteriorly The femur The femur is the longest bone of the human body. Its shape and robust stature reflect the powerful action of muscles and contribute to the long stride length during walking. At its proximal end, the femoral head projects medially and slightly anteriorly to articulate with the acetabulum. The femoral neck connects the femoral head to the shaft. The neck serves to displace the proximal shaft of the femur laterally away from the joint, thereby reducing the likelihood of bony impingement against the pelvis.  The femoral head is oriented Superiorly Medially Anteriorly The head is supported by the neck of femur which joins the shaft SHAPE OF THE PROXIMAL FEMUR The ultimate shape and configuration of the developing proximal femur are determined by several factors, including differential growth of the bone’s ossification centers, the force of muscle activation and weight bearing, and circulation. Abnormal growth and development resulting in a misshaped proximal femur is referred to generically as femoral dysplasia. Trauma or other systemic factors can also affect the shape of the proximal femur.  The joint allows three degree of freedom 1. Flexion and extension in the sagittal plane 2. Abduction and adduction in the frontal plane 3. Medial and lateral rotation in the transverse plane Angles within hip joint 1- Central edge angle of the acetabulum Located between two lines the first line connects between the lateral rim of the acetabulum and the center of the femoral head The second line is the vertical line passing through the center of the femoral head It is average value is 22-42 Center edge angle Its function To provide lateral stability of the pelvis Large angle means increased inferior tilting of the acetabulum and increased diameter of the pelvis as increase the coverage of the head of the femur Smaller angle result in diminished coverage of the head of the femur 2- angle of inclination of the femur Or Neck shaft angle Located between the anatomical axis of the femoral neck and the anatomical axis of the femoral shaft in the frontal plane At birth this angle measures, on average, about 165–170 degrees. Primarily because of muscle activity and loading across the femoral neck during walking, this angulation usually decreases by about 2 degrees per year between 2 and 8 years of age. The angle of inclination continues to decrease by varying rates until reaching its normal adulthood value of about 125 degrees A change in the normal angle of inclination is referred to as either coxa vara or coxa valga. Coxa vara describes an angle of inclination markedly less than 125 degrees coxa valga describes an angle of inclination markedly greater than about 125 degrees Abnormal angles can significantly alter the articulation between the femoral head and the acetabulum, thereby affecting hip biomechanics. Severe malalignment may lead to dislocation or stress-induced degeneration of the joint. Although variable, persons with cerebral palsy typically possess a coxa valga deformity. 3- Angle of torsion of the femur The angle located between the axis of femoral neck and the axis of femoral condyles in the transverse plane Normal value is 15 ( 10-30 ) The angle decrease with age Femoral torsion describes the relative rotation (twist) between the bone’s shaft and neck. Typically, as viewed from above, the femoral neck typically projects several degrees anterior to a medial-lateral axis through the femoral condyles. Typically a healthy infant is born with about 40 degrees of femoral anteversion. With continued bone growth, increased weight bearing, and muscle activity, this angle usually reduces to about 15 degrees by 16 years of age. Excessive anteversion that persists into adulthood can increase the likelihood of hip dislocation, articular incongruence, increased joint contact stress, and increased wear on the articular cartilage or acetabular labrum. These factors may lead to secondary osteoarthritis of the hip. Excessive anteversion in children may be associated with an abnormal gait pattern called “in-toeing.” In-toeing is a walking pattern with exaggerated posturing of lower limb internal rotation. This gait pattern may be a compensation to guide the excessively anteverted femoral head more directly into the acetabulum. In-toeing typically persists in children with cerebral palsy who are ambulatory.192 Spasticity or tightness of hip internal rotator and adductor muscles along with excessive pelvic rotation may contribute to the in-toeing posturing. In select cases, a femoral de-rotational osteotomy may be considered as a way of reducing the excessive internal rotational posturing observed in gait. Capsule of the hip joint The capsule of the hip joint is strong and dense and shpad like a cylindrical sleeve. It is attached to the entire periphery of the acetabulum and covers the femoral neck The neck is intracapsular whereas the greater and lesser trochanters are extracapsular The capsule is thickened anterosuperiorly where the stress occur. While is relatively thin and loosely attached posteroinferiorly Ligaments of the hip joint The capsule of the hip joint is strengthened by powerful ligaments anteriorly and posteriorly. Anteriorly two lig are present illiofemoral and pubofemoral Posteriorly there is only one lig ischiofemoral lig Illiofemoral ligament Fan shaped lig that resembles an inverted letter Y Proximally, the iliofemoral ligament attaches near the anterior-inferior iliac spine and its base is inserted into the whole length of the trochanteric line Function of illiofemoral ligamnet 1. It becomes taut during hyperextension so it is limit this motion. 2. Superior fibers become taut during adduction 3. The ligament becomes taut during lateral rotation 4. The ligament reinforces the front part of the capsule Pubofemoral ligament The pubofemoral ligament attaches along the anterior and inferior rim of the acetabulum and adjacent parts of the superior pubic ramus. The bands of illiofemoral and pubofemoral lig form Z letter on the anterior capsule Its function The fibers becoming taut in hip abduction and extension and, to a lesser degree, external rotation. ischiofemoral ligament The ischiofemoral ligament attaches from the posterior aspect of the acetabulum to attach near the apex of the greater trochanter. Its function The fibers becoming taut in hip abduction and extension And medial rotation Thank you