HIP ARTHOLOGY Flashcards
Identify the bones in articulation at the hip joint
- Acetabulum - socket
- Head of femur - ball
Both covered in hyaline cartilage
Reciprocally curved the articular surfaces are incongruent (don’t fit well)
resulting in limited S.A contact at low loads and increases as load increase
This distributes load and protects the underlying cartilage and bone from excessive stress
Shape + extent of articulating surfaces
head of femur
Head of femur
- 2/3 of a sphere slightly compressed anteroposteriorly
- small depression on the head= fovea capitis for attachment of ligament teres
Describe arrangement of articular cartilage at hip joint
Acetabulum
Acetabulum
* hemispherical socket (concave) deficient interiorly prominent rim = (acetabular notch)
- central part is thin walled non- articular acetabular fossa formed by the ischium
- Lateral (outer) surface of the innominate bone
*Formed of 3 bones
2/5th Ilium
2/5th Ischium
1/5th Pubis
*Semilunar articular surface
*Thin-walled, central part (acetabular fossa) non-articular
Articular surface covered in Articular Hyaline Cartilage
Describe attachments of fibrous capsule of hip joint (joint capsule)
Strong fibrous capsule thicker anteriorly and superiorly
Acetabulum superiorly and posteriorly
Acetabulum and acetabulum labrum anteriorly and inferiorly and transverse ligament
Intertrochanteric line and neck anteriorly and posteriorly to medial 2/3 to neck of femur
Longitudinal fibres: acetabulum to femur
Oblique fibres: acetabulum to femur
Arcuate: one part of acetabulum to other
Zona obicularis: deepest no boney attachments wrap round capsule
Where are the areas that the capsule is thickest
Anteriorly+Superiorly
Strengthened anteriomedially by the reflected head of rectus femoris + laterally by gluteus minimums
Capsule thicker anterosuperiorly where maximal stress occurs
Special features/ direction of fibre of capsule
Majority of capsule fibre run from the innominate to femur
The capsule is a mix of connective tissue fibres of different arrangements and orientation
4 fibres of capsule
- Longitudinal
- Oblique
- Arcuate
- Zona Orbicularis
Longitudinal fibres
Run parallel to axis of the cylinder pass from acetabular to femoral attachments (straight line between femoral head and acetabulum)
Main longitudinal capsular fibre form thickened bands which resist tensile stress which the capsule is subjected
Deeper fibres upon reaching the femoral neck turn upwards towards articular margin
Oblique fibres
Spiral around the cylinder between their attachments unite articular surfaces
Arcuate fibres
Arch from one part of the acetabular rim to the other helps femoral head within acetabulum
Deeper fibres run circularly around capsule and have no bones attachments
Synovial membrane overview, function
Function: lines joint capsule and non articulating bones inside capsule
Membrane accumulates adipose tissue, larger accumulations= articular fat pads
Fat pads= form flexible cushions which fill potential spaces and irregularities of joint
Internal synovial surface= synovial vile increase S.A
Structure synovial membrane
2 layers
1.Cellular Intima Supported by ⬇️
Cells lining cellular intima =SYNVIOCYTES
- Fibrovascular Subintimal lamina
Contains some elastic component which prevents redundant folds
being formed during joint movement
Cellular Intima (synoviocytes)
Two types = A + B
A: removal of debris , form part of macrophage system
B: production of synovial fluid
> some can produce antigens immune response in joint
Bursa
A sack of fluid naturally occurring
Main role is to improve the efficiency how a joint moves or a muscle/tendon acts around a joint
Function ligaments
Prevent excessive or abnormal movement occurring at joint but offer no resistance to normal movement
Capsular ligaments of HIP
[extracapsular]
ILIOFEMORAL
PUBOFEMORAL
ISCHIOFEMORAL
ILIOFEMORAL ligament
Shape,attachments, position,role
Shape: Y shaped , thick 🔺ular ligament
Attachments: *Apex attaches to the lower part of anterior inferior iliac spine and adjacent acetabular rim+ base to intertrochantic line of femur
*Outer bands attach the upper / lower parts of the intertrochanteric line= strongest parts and central part is thinner and weaker
Position: anterior to joint between lower part of anterior inferior iliac spine adjacent to acetabular rim and intertrochanteric line
Role: prevents hyper extension of the hip strongest of 3 ligaments
Limits: lateral rotation, extension adduction - (upper band) abduction-( lower band)
PUBOFEMORAL ligament
Shape,attachments, position, role
Shape: 🔺ular, strong narrow ligament, inferiorly
situated
Attachments: runs from the iliopubic eminence, superior pubic ramus to lower part of intertrochanteric line blending with the inferior band of the iliofemoral ligament
Position: Anterior and inferior to the joint between the iliopubic eminence and superior pubic ramus and lower intertrochanteric line
Role: strengthens the anteroinferior aspect of joint
limits extension lateral rotation and abduction
ISCHIOFEMORAL ligament
Shape,attachments, position, role
Shape: less well defined spiral ligament, spirals superolaterally around capsule
Attachments: runs between the body of the ischium, superior part of neck of femur and root of greater trochanter
Position: Posterior of the hip.
Role: limits extension, medial rotation, adduction and prevents hyper-extension holds femoral head in acetabulum
Intra-articular structures - (4)
(Structures other than ligaments in joints)
[inracaspular]
- Transverse acetabular ligament
- Acetabular labrum
- Ligamentum teres
- Acetabular fat pad
Intra and extra capsular
INTRACAPSULAR
- Transverse acetabular ligament
- Acetabular labrum
- Ligamentum teres
- Acetabular fat pad
EXTRA CAPSULAR
- ILIOFEMORAL
- PUBOFEMORAL
- ISCHIOFEMORAL
Transverse acetabular ligament
Position, attachments, function
Position: inferior deficiency in the acetabular rim is completed by the transverse acetabular ligament (portion of acetabular labrum)
Attachments: bridges the acetabular notch and joins the 2 ends of the acetabular labrum forming complete rim connected with he ligament of the head of femur and articular capsule
Function: supports part of the acetabular labrum
Acetabular labrum
Shape,extent/nature,function
Shape:🔺ular in cross section
Extent/nature: fibrocartilage rim attaches to the outer surface of the acetabulum and transverse ligament which enhances depth of acetabulum
Function: enhances depth of acetabulum which means dislocation is rare.
Cups round head of femur holding it firmly socket
Ligamentum teres (ligament of the head of the femur)
Position,Attachments , function
flat 🔺ular band primarily a synovial fold
Position: extends from fossa of acetabulum to fovea capitis of head of femur
Attachments: attached to adjacent margins of the acetabular notch and transverse ligament narrowing as it passes to insert into fovea capitis
Function: contains small artery that supplies head of femur appears to be of little importanance in strengthening hip
Acetabular fat pad
Position, function
Position: lies within acetabular fossa where femoral head is not
Function: cushion prevent friction
fibroelastic fat pad contains numerous proprietary receptive nerve endings so when compressed or partially extruded
from acetabular fossa beneath the transverse ligament additional proprioreceptive info about hip movement is provided
Close packed position of hip
Due to the hip ligaments tightening in extension, this is the point of highest joint stability, and therefore the close pack position (extension, adduction, medial rotation).
Open packed position
The hip joint is different from most joints in the fact that it’s open pack position (flexion, abduction, lateral rotation) is actually where the joint surfaces are in least contact with each other.
It is more often the close pack position where the is the case in other joints.
Blood and nerve supply (general)
All synovial joints have a rich blood supply especially synovial membrane and capsule = derived from branches of main blood vessels in vicinity of joint
Hilton’s law
Branches of nerves which supply the muscles acting on the joint
Most articular nerves end in sensory receptors in capsule+ ligaments - synovial membrane has few nerve endings= insensitive to pain
Nerve supply to hip
Primarily : sciatic, femoral and obturator
Blood supply to hip
Receive a blood from medial+lateral circumflex femoral, obturator, superior and gluteal arteries forming a periorticular anastomosis around joint
Hip stability is determined by
- shape/angle of bone
- Strong reinforcing ligament
- acetabular labrum
- muscles crossing joint
Movements at HIP
Flexion/extension x2
Abduction/adduction
Medial/lateral rotation
Angle of inclination
Normal Between 120-125^
In frontal plane the angle between head neck and shaft of femur
Greater than 130^ = reduced stability
angle of anteversion
Normal 15^
In the horizontal plane outward rotation of head and neck of femur against the shat
Greater 15^= reduced stability
Classifying Hip
Classification:
Synovial: Synovial membrane, capsule, hyaline cartilage
Simple: There are no intervening structures between the bones; there are only two bones articulating at this joint (innominate bone and femur)
Multi-axial: The hip undertakes movement in three planes;
Sagittal (Flexion/Extension);
Frontal/coronal (Abduction/Adduction);
Transverse (Medial Rotation/Lateral Rotation)
Shape: Ball (head of femur) and socket (acetabulum)
Shape and extent of articulating surface
acetabulum
Acetabulum
* hemispherical socket (concave) deficient interiorly prominent rim = (acetabular notch)
- central part is thin walled non- articular acetabular fossa formed by the ischium
- Lateral (outer) surface of the innominate bone
*Formed of 3 bones
2/5th Ilium
2/5th Ischium
1/5th Pubis
*Semilunar articular surface
*Thin-walled, central part (acetabular fossa) non-articular
Articular surface covered in Articular Hyaline Cartilage
Zona Orbicularis
Deep (innermost) part of the capsule. No bony attachment. Run in a circular fashion around the capsule, strengthening it
