BIOMECHANICS OF
HIP JOINT
ANATOMY OF
HIP JOINT
The hip joint is a ball and socket synovial joint,
formed by an articulation between the pelvic
acetabulum and the head of the femur.
It forms a connection from the lower limb to
the pelvic girdle, and thus is designed for
stability and weight-bearing – rather than a
large range of movement
HIP JOINT
The acetabulum is a cup-like depression located
on the inferolateral aspect of the pelvis. Its
cavity is deepened by the presence of a
fibrocartilaginous collar – the acetabular labrum.
The head of femur is hemispherical, and fits
completely into the concavity of the acetabulum.
The capsule of the hip joint attaches to the edge
of the acetabulum proximally. Distally, it
attaches to the intertrochanteric line anteriorly
and the femoral neck posteriorly.
LIGAMENTS
Ligaments
The ligaments of the hip joint act to increase
stability.
They can be divided into two groups –
1: intracapsular
2: extracapsular
INTRACAPSULAR
Intracapsular
The only intracapsular ligament is the ligament
of head of femur.
It is a relatively small structure, which runs from
the acetabular fossa to the fovea of the femur.
It encloses a branch of the obturator
artery (artery to head of femur), a minor source
of arterial supply to the hip joint.
EXTRACAPSULAR
Extracapsular
There are three main extracapsular ligaments,
continuous with the outer surface of the hip joint
capsule:
Iliofemoral ligament – arises from the anterior
inferior iliac spine and then bifurcates before
inserting into the intertrochanteric line of the
femur.
EXTRACAPSULAR
Pubofemoral – spans between the superior
pubic rami and the intertrochanteric line of the
femur, reinforcing the capsule anteriorly and
inferiorly.
Ischiofemoral– spans between the body of
the ischium and the greater trochanter of the
femur, reinforcing the capsule posteriorly.
MUSCLES OF HIP
JOINT
MOVEMENTS
Flexion – iliopsoas, rectus femoris, sartorius,
pectineus
Extension – gluteus maximus; semimembranosus,
semitendinosus and biceps femoris (the hamstrings)
Abduction – gluteus medius, gluteus minimus,
piriformis and tensor fascia latae
Adduction – adductors longus, brevis and magnus,
pectineus and gracilis
MOVEMENTS
Medial rotation – anterior fibres of gluteus
medius and minimus, tensor fascia latae
Lateral rotation – biceps femoris, gluteus
maximus, piriformis, assisted by the
obturators, gemilli and quadratus femoris.
COMMON INJURIES
OF HIP JOINT
Fractures:-
Femoral neck fracture: A femoral neck fracture
occur during the support phase of walking . These
fractures are common among older adults and
can be related to osteoporosis. This type of
fracture may cause a complication because the
break usually cuts off the blood supply to the
head of the femur which forms the hip joint.
Regular physical activities helps to protect against
risk of hip fracture.
Contusions:-
The resulting internal hemorrhage andappearance
of bruises vary from mild to severe.Acute
compartment syndrome in which internal
bleeding causes a build up pressure in the muscle
compartment causing compression on nerves,
blood vessels and muscles .If not treated , this
can lead to tissue death due to lack of
oxygenated blood vessels are compressed.
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Strains:-
Because most daily activities donot require
simultaneous hip flexion and knee extension.
The resulting loss of extensibility makes the
hamstring particularly to strain.Strains to these
muscles most commonly accur during sprinting ,
particularly if the individual is fatigue and
neuromuscular coordination is impared .
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