Hip joint capsule & ligaments:Hip joint capsule & ligaments:Capsule:Capsule:• Strong & denseStrong & dense• Substantial contributor for joint stabilitySubstantial contributor for joint stability• It is attached to the entire periphery of the It is attached to the entire periphery of the

acetabulumacetabulum• It covers the femoral neck like a sleeve and It covers the femoral neck like a sleeve and

attaches to the base of the neck – femoral neck is attaches to the base of the neck – femoral neck is intracapsular whereas greater and lesser intracapsular whereas greater and lesser trochanters are extracapsulartrochanters are extracapsular

• It is thick anterosuperiorly where predominant It is thick anterosuperiorly where predominant stresses occur while it is thin and loose stresses occur while it is thin and loose posteroinferiorlyposteroinferiorly

Ligaments:Ligaments:• Ligamentum teresLigamentum teres/ligament of head of femur/ligament of head of femur• Doesn't play a significant role in stabilization Doesn't play a significant role in stabilization • Functions primarily as a conduit for the Functions primarily as a conduit for the

secondary blood supply from the secondary blood supply from the

obturator artery and for the obturator artery and for the

nerves that travel along the nerves that travel along the

ligament to reach the head ligament to reach the head

through the foveathrough the fovea

• Hip joint capsule is reinforced by 3 ligaments Hip joint capsule is reinforced by 3 ligaments – 2 anteriorly and 1 posteriorly– 2 anteriorly and 1 posteriorly

Anterior:Anterior:• Ilio femoral ligament(Y lig.of Bigelow)Ilio femoral ligament(Y lig.of Bigelow)• Pubofemoral ligamentPubofemoral ligament• Fibers of both these ligamentsFibers of both these ligaments

form a Z on the anterior capsuleform a Z on the anterior capsule

Posterior:Posterior:• Ischiofemoral ligamentIschiofemoral ligament

• Hip joint capsule and ligaments are quite Hip joint capsule and ligaments are quite strongstrong

• Joint is difficult to traumatically dislocate Joint is difficult to traumatically dislocate • In bilateral stance, hip is typically in neutral In bilateral stance, hip is typically in neutral

position or slight extension – in this position position or slight extension – in this position ligaments and capsule are under some tensionligaments and capsule are under some tension

• LOG in bilateral stance falls behind the hip LOG in bilateral stance falls behind the hip joint axis, creating a gravitational extension joint axis, creating a gravitational extension torquetorque

Weight-bearing structure of Hip Joint:Weight-bearing structure of Hip Joint:• Internal architecture of pelvis and femur reveal Internal architecture of pelvis and femur reveal

remarkable adaptations occurred to accommodate remarkable adaptations occurred to accommodate mechanical stresses ‘n’ strains created by mechanical stresses ‘n’ strains created by transmission of forces between femur and pelvistransmission of forces between femur and pelvis

• Trabeculae of bone line up along lines of stress Trabeculae of bone line up along lines of stress and form systems to meet stress requirementsand form systems to meet stress requirements

• Weight bearing occurs through vertebrae to the Weight bearing occurs through vertebrae to the sacral promontory and on through the sacroiliac sacral promontory and on through the sacroiliac joints joints

• Weight bearing lines of both pelvis and femur are Weight bearing lines of both pelvis and femur are evident by the arrangement of trabeculae evident by the arrangement of trabeculae

• Most of the weight bearing stresses in the Most of the weight bearing stresses in the pelvis pass from the sacroiliac joints to the pelvis pass from the sacroiliac joints to the acetabulum, although the trabeculae show acetabulum, although the trabeculae show evidence of some forces along the pubic evidence of some forces along the pubic ramus and along the ischial tuberositiesramus and along the ischial tuberosities

• The pelvic trabeculae that pass through The pelvic trabeculae that pass through the acetabulum of the pelvis form two the acetabulum of the pelvis form two major systems within the femur: major systems within the femur:

a)a) Medial trabecular systemMedial trabecular systemb)b) Lateral trabecular systemLateral trabecular system• There are two minor accessory systems of There are two minor accessory systems of

trabeculaetrabeculae

Trabecular system

• In bilateral static stance, weight of HAT is In bilateral static stance, weight of HAT is distributed between left and right hip joints distributed between left and right hip joints with the force of at least half the with the force of at least half the superimposed body weight, travelling down superimposed body weight, travelling down the femoral head, while the ground reaction the femoral head, while the ground reaction force (GRF) travels up the shaftforce (GRF) travels up the shaft

• The distance between the super imposed The distance between the super imposed body weight on the head and the GRF up body weight on the head and the GRF up the shaft creates a bending force at the the shaft creates a bending force at the femoral neckfemoral neck

• The trabecular systems must resist this The trabecular systems must resist this bending forcebending force

• Medial and lateral trabecular systems not Medial and lateral trabecular systems not only contribute to the structure of head and only contribute to the structure of head and neck of femur but also help resist bending neck of femur but also help resist bending stresses as the weight of HAT passes down stresses as the weight of HAT passes down on the femoral headon the femoral head

• Areas in which various trabecular systems Areas in which various trabecular systems cross each other at right angles are areas cross each other at right angles are areas that offer greatest resistance to stress and that offer greatest resistance to stress and strainstrain

• An area in the femoral neck in which An area in the femoral neck in which trabeculae are relatively thin and do not trabeculae are relatively thin and do not cross over is called as cross over is called as ‘Zone of weakness’‘Zone of weakness’

Zone of weakness:Zone of weakness:• Area where trabeculae don't cross at right Area where trabeculae don't cross at right

angelsangels• Less reinforcement by trabeculaeLess reinforcement by trabeculae• More potential for injuryMore potential for injury• This zone is susceptible to bending forces and This zone is susceptible to bending forces and

can fracture when forces are excessive or when can fracture when forces are excessive or when tissues are no longer able to resist normal tissues are no longer able to resist normal forcesforces

Functions of Hip Joint:Functions of Hip Joint:

Arthrokinematics:Arthrokinematics:• Hip joint involves movement of a convex femoral Hip joint involves movement of a convex femoral

head within the concave acetabulumhead within the concave acetabulum• Head glides within the acetabulum in a direction Head glides within the acetabulum in a direction

opposite to the motion of distal end of femuropposite to the motion of distal end of femur• From a neutral position flexion and extension From a neutral position flexion and extension

occurs as almost pure “spin” of femoral head occurs as almost pure “spin” of femoral head around a coronal axis through the head and neck around a coronal axis through the head and neck of femurof femur

• Head spins posteriorly in flexion and anteriorly in Head spins posteriorly in flexion and anteriorly in extensionextension

• However, flexion and extension from other However, flexion and extension from other positions must include both “spinning” and positions must include both “spinning” and “gliding” of articular surfaces“gliding” of articular surfaces

• Motions of abduction/adduction and Motions of abduction/adduction and medial/ lateral rotation must include both medial/ lateral rotation must include both spinning and gliding of one surface over the spinning and gliding of one surface over the other,but again occur opposite to motion of other,but again occur opposite to motion of distal end of femur when femur is the distal end of femur when femur is the moving segmentmoving segment

• Whenever hip joint is weight bearing Whenever hip joint is weight bearing (femur is relatively fixed) and motion of hip (femur is relatively fixed) and motion of hip joint is produced by movement of pelvis on joint is produced by movement of pelvis on femurfemur

Osteokinematics:Osteokinematics:Motion of femur at hip joint:Motion of femur at hip joint:• ROM available at hip joint is most commonly ROM available at hip joint is most commonly

described by movement of femurdescribed by movement of femur• ROM is influenced by whether it is performed ROM is influenced by whether it is performed

actively or passively and whether passive tension actively or passively and whether passive tension in two joint muscles is encountered or avoidedin two joint muscles is encountered or avoided

• Following are the ranges of passive motion:Following are the ranges of passive motion:1.1. FlexionFlexion :90 :90 with knee extended and 120 with knee extended and 120-135-135

when knee is flexed & passive tension in when knee is flexed & passive tension in hamstrings is releasedhamstrings is released

2.2. ExtensionExtension :10 :10-30-30, when hip extension is , when hip extension is combined with knee flexion, passive tension in combined with knee flexion, passive tension in rectus femoris may limit the movementrectus femoris may limit the movement

3.3. AbductionAbduction:45:45-50-50 can be limited by can be limited by gracilis musclegracilis muscle

4.4. AdductionAdduction:20:20-30-30 can be limited by TFL can be limited by TFL and associated IT bandand associated IT band

5.5. Medial rotationMedial rotation: 30-45: 30-45(hip in 90(hip in 90 flexion) flexion)6.6. Lateral rotationLateral rotation: 45-60: 45-60 Normal gait on level ground requires at Normal gait on level ground requires at

least the following ranges:least the following ranges:• 3030 flexion flexion• 1010 hyperextension hyperextension• 55 of abduction and adduction of abduction and adduction• 55 of medial and lateral rotation of medial and lateral rotation

Motion of pelvis at hip joint:Motion of pelvis at hip joint:• When proximal segment of joint moves on When proximal segment of joint moves on

distal part, the motion is the same as if the distal part, the motion is the same as if the distal distal segment were the moving part were the moving part

• However, the direction of movement of the However, the direction of movement of the lever reverseslever reverses

• For e.g. elbow flexion can be a movement of For e.g. elbow flexion can be a movement of distal forearm upwards or conversely a distal forearm upwards or conversely a rotation of proximal humerus downwardrotation of proximal humerus downward

• At the hip joint, this reversal of motion of At the hip joint, this reversal of motion of lever is complicated by the horizontal lever is complicated by the horizontal orientation and nonlever shape of pelvis orientation and nonlever shape of pelvis

• Unlike at other joints there is a new set of Unlike at other joints there is a new set of terms to identify joint motion when pelvis is terms to identify joint motion when pelvis is the moving segmentthe moving segment

• Terms of pelvic motion are used with weight-Terms of pelvic motion are used with weight-bearing hip motion because these are the bearing hip motion because these are the motions that are visible motions that are visible

• These motions are also key to what occurs at These motions are also key to what occurs at above or below joints of pelvisabove or below joints of pelvis

Anterior and Posterior Pelvic Tilt:Anterior and Posterior Pelvic Tilt:• Are motions of pelvis in saggital plane Are motions of pelvis in saggital plane

around a coronal axisaround a coronal axis• In a normally aligned pelvis the ASIS lie on In a normally aligned pelvis the ASIS lie on

a horizontal line with PSIS and on a vertical a horizontal line with PSIS and on a vertical line with symphysis pubisline with symphysis pubis

• Anterior and posterior tilting Anterior and posterior tilting of the pelvis on a of the pelvis on a fixed femur produces fixed femur produces hip flexion & extension hip flexion & extension respectivelyrespectively

Posterior tilting:Posterior tilting:• Posterior tilting of the pelvis moves Posterior tilting of the pelvis moves

symphysis pubis superiorly and the lumbar symphysis pubis superiorly and the lumbar spine flexes slightly, hip joint extendsspine flexes slightly, hip joint extends

• Hip extension via posterior tilting brings Hip extension via posterior tilting brings symphysis pubis up and posterior part of the symphysis pubis up and posterior part of the pelvis closer to the femur rather than pelvis closer to the femur rather than moving femur posteriorlymoving femur posteriorly

Anterior tilting:Anterior tilting:• Anterior tilting of pelvis moves symphysis Anterior tilting of pelvis moves symphysis

pubis inferiorly and lumbar spine is hyper pubis inferiorly and lumbar spine is hyper extended ,hip joint is flexedextended ,hip joint is flexed

• Hip flexion through anterior tilting of the Hip flexion through anterior tilting of the pelvis brings ASIS anterior and inferiorly, pelvis brings ASIS anterior and inferiorly, symphysis pubis moves down and closer to symphysis pubis moves down and closer to the femurthe femur

• Anterior and posterior tilting can result in Anterior and posterior tilting can result in flexion and extension of both hip joints flexion and extension of both hip joints simultaneously or can occur at a stance hip simultaneously or can occur at a stance hip joint if the opposite limb is non weight joint if the opposite limb is non weight bearingbearing

Lateral Pelvic tilt:Lateral Pelvic tilt:• Occurs in a frontal lane and around A-P axisOccurs in a frontal lane and around A-P axis• In a normally aligned pelvis line passing In a normally aligned pelvis line passing

through both the ASIS is horizontalthrough both the ASIS is horizontal• If this line is not horizontal lateral tilt has If this line is not horizontal lateral tilt has

occurredoccurred• This can occur in unilateral or bilateral stanceThis can occur in unilateral or bilateral stance

• In lateral tilt of pelvis in unilateral stance, In lateral tilt of pelvis in unilateral stance, one hip joint is the pivot point or axis of one hip joint is the pivot point or axis of motion of the opposite side of the pelvis as motion of the opposite side of the pelvis as it elevates(hiking) or drops(pelvic drops)it elevates(hiking) or drops(pelvic drops)

Pelvic Rotation:Pelvic Rotation:• Rotation of entire pelvis in a transverse lane Rotation of entire pelvis in a transverse lane

around a vertical axisaround a vertical axis• Forward rotation of pelvis occurs when the Forward rotation of pelvis occurs when the

side of the pelvis opposite to the supporting side of the pelvis opposite to the supporting hip joint moves anteriorly.This produces hip joint moves anteriorly.This produces medial rotation of the supporting hip jointmedial rotation of the supporting hip joint

• Backward rotation of the pelvis occurs Backward rotation of the pelvis occurs when the side of pelvis opposite the when the side of pelvis opposite the supporting limb moves posteriorly.This supporting limb moves posteriorly.This produces lateral rotation of supporting hip produces lateral rotation of supporting hip jointjoint