Lecture 23: Hip Joint Flashcards
What joint connects the pelvis to the sacrum
iliosacral joint
Describe the bones of the hip joint
The head of the femur articulates with the acetabulum: the three pelvic bones (not fused until puberty).
The circle is completed by the Transverse Acetabular ligament which covers the acetabular notch. This suspends the head of the femur.
What features of the hip joint promote stability -
- Femoral head is covered more than 50% by acetabulum - acetabular labrum increases articulating area- deepens the socket.
- Very strong joint capsule with thickenings made of ligaments that pull the femur medially into the hip joint, reinforce the joint and prevent hyperextension and overabduction.
- Thickening of the lower half of the femoral neck to support transfer of force through hip joint
- Femoral head articulates with the acetabulum superomedially and anteriorly by angle of ~12’
Describe whats inside the hip joint- the articulating surfaces etc
The head of the femur is covered in hyaline articular cartilage except from the fovea area. The articular cartilage in the acetabulum is the lunate surface which leaves an acetabular fossa in the centre and has the acetabular fibrocartilage labrum around it
Here it is filled with fat and some v weak arteries from obturator. From the acetabular notch to the fovea extends the weak Ligamentum Teres with its own artery which was useful in fetal development but not really now
What features of the hip joint promote movement
- Multiaxial ball and socket joint
- large head of femur with relatively thin neck
- the angle of the femoral neck to the long axis of the femur is ~125’ which allows for greater mobility but also a lot of force through the neck.
- Fibrous part of the joint capsule enables some movement through spiral attachment
Where does the joint capsule for hip joint attach
From: acetabulum and transverse acetabular ligament to: intertrochanteric line of femur.
Where does the iliofemoral ligament attach and what is its purpose
Attaches from AInferiorIS to intertrochanteric line (2 inserts (Y))
Purpose: superior anterior reinforcement which prevents hyperextension by corkscrew
Where does the Pubofemoral ligament attach and what is its purpose
Attaches from pubis to blend with joint capsule.
Purpose: inferior anterior reinforcement which prevents over-abduction and tightens in extension
Where does the Ischiofemoral ligament attach and what is its purpose
Attaches from Ischial part of acetabular rim and spirals to base of greater trochanter.
Purpose: posterior reinforcement which prevents hyperextension by corkscrew
What is the zona obicularis
Fibres of the joint capsule which reinforce the hip joint in a ring around the head
What is the arterial supply to the femoral head and neck
The medial circumflex artery runs posteriorly and meets up with the lateral circumflex artery which runs anteriorly to form the lateral anastomosis.
From these arteries are the Retinacular Arteries which run in the retinacular folds of the synovial membrane of the joint. These supply the femoral neck and head
What is Hiltons law
A nerve that crosses a joint will supply the joint as well. A nerve that supplies a muscle that crosses a joint will supply sensation to that joint too.
What are the 4 nerves that supply the hip joint
Femoral nerve (anteriorly), Obturator nerve (inferiorly), Superior Gluteal nerve, and Nerve to Quadratis femoris (posteriorly)
What leads to neck of femur fractures in young vs old. What determines treatment
High energy trauma in young vs Low energy falls in older patients, osteoporosis and tumour in old.
The place of fracture in relation to blood supply determines treatment
What is the common way the hip joint is dislocated
Can be dislocated anteriorly or posteriorly (90%).
Posterior is when hip is flexed, adducted and internally rotated so the femoral head moves superiorly leading to short internally rotated leg.