BIOMECHANICS OF hip
PresentedBy
Dr. Nazish RafiqueLecturer
ZCPT
Function of HipThe primary function of the hip joint
is to support the weight of the head, arms, and trunk (HAT) both in static erect posture and in dynamic postures such asAmbulation,Running,Stair climbing.
Structure of HipThe hip joint or coxofemoral joint
Articulation with the acetabulum of the pelvis and the head of the femur
Ball-and-socket joint
Synovial joint
Bones of HipIliumIschiumPubisFemur
The acetabulum is formed by the pubis, ischium and ilium bones
The pubis forms one fifth of the acetabulum
The ischium forms two fifths
The ilium forms the remainder
Femoral Head
The head of the femur, which forms approximatelytwo-thirds of a sphere.
Acetabulum Acetabular surface is covered with
articular cartilage that thickens peripherally and laterally
Osseous acetabulum is deep and provides static stability
Acetabular cavity is deepened by the labrum, flat rim of fibrocartilage, transverse acetabular ligament
Center edge (CE) angle / angle of Wiberg
A line connecting the lateral rim of the acetabulum and the center of the femoral head.
This line forms an angle with the vertical
The amount of inferior tilt of the acetabulum.
CE angles in adults to average 38º in men and 35º in women
The entire periphery of the acetabulum is rimmed by a ring of wedge-shaped fibrocartilage
Hydrostatic fluid pressure within the intra-articular space was greater within the labrum than without,
The labrum may also enhance joint lubrication if the labrum adequately fits the femoral head.
Removal of the transverse acetabular ligament and labrum did not affect the loading pattern of the acetabulum
Acetabular labrum
Joint CapsuleStrong fibrous sleeveAnteriorly
Proximally to the bone surrounding the acetabulum.
Distally to the trochanteric linePosteriorly
To the margins of the acetabulum and surrounding bone
Neck of the femur- not to the trochanteric crest
Joint CapsuleThe capsule is thickened anterosuperiorly,
where the predominant stresses occurRelatively thin & loosely attached
posteroinferiorlyThe femoral head & neck is intracapsular,Both the greater & lesser trochanters are
extracapsular.The synovial membrane lines the inside of
the capsule.
Joint CapsuleIntrinsic stability is provided by the
congruency of joint structure, and ligamentous support
Prone to dislocation in a position of flexion , abduction and internal rotation (dashboard injury)
Posterior capsule is relatively weakerClose packed position is extension/
abduction/ internal rotation and flexion (90º)/ abduction/ external rotation