The Hip Flashcards
Describe the 3 portions of the acetabulum.
Lunate surface = articulates with the femoral head and is covered with hyaline cartilage
Acetabular fossa = deepest portion of the acetabulum
Acetabular Notch = 60 -70 degrees wide opening in inferior acetabulum.
What is the deepest portion of the acetabulum?
The acetabular fossa
What surface of the acetabulum articulates with the femoral head and is covered in hyaline cartilage?
Lunate surface
What is the wide opening in the inferior acetabulum?
Acetabular notch
Describe the orientation of the neck of the femur.
Angulated so head faces medially, superiorly and anteriorly with respect to the femoral shaft and distal femoral condyles.
What is the angle of inclination?
Angle between axis through femoral head/neck and longitudinal axis of the femoral shaft.
Typically 125 degrees
What does coxa valga indicate?
A pathological increase in angle of inclination.
> 125 degrees
What does coxa vara indicate?
A pathological decrease in angle of inclination.
<125 degrees
What is the purpose of the angle of inclination?
Serves to optimize joint surface alignment.
What can cause a slipped capital femoral epiphysis in adolescents?
A decrease in femoral neck shaft angle along with a high body mass index.
What is the angle of torsion?
Angle between axis through femoral head/neck and the distal femoral condyles.
Normal = 8 - 20 degrees
What allows for optimal alignment and joint congruency?
15 degrees of anteversion.
Describe what is seen with excessive anteversion.
Increased angle of torsion.
- Reduces hip joint stability
- Associated with increased hip IR and decreased ER
- Commonly found with coxa valga
Describe what is seen with retroversion.
Decreased angle of torsion.
- Associated with increased hip ER and decreased IR
- May cause impingement
What may be associated with “in-toeing” gait in children?
Excessive anteversion
What does the “in-toeing” aim to do?
Improve joint congruency.
But overtime may cause shortening of muscles and ligaments crossing hip and reduce ER.
What is the positioning of the acetabulum?
Opening positioned laterally with inferior and anterior tilt.
What determines the coverage of the femoral head?
The depth of acetabulum.
What is acetabular dysplasia?
Abnormality where acetabulum is shallow.
What is coxa profunda?
Abnormality of acetabular over-coverage. Excessively covers femoral head.
What can excessive retroversion lead to?
over-coverage/impingement
What can excessive anteversion lead to?
Instability
Describe a Cam deformity.
When extra bone is present at anterior-superior region of femoral head and neck junction.
- As result there is loss of natural tapering of femoral head.
What causes impingement in a Cam deformity?
Bulge of femoral head hits against the acetabulum.
*IR with FL maximizes impingement.
Describe a Pincer deformity.
Abnormal bony extension of anterior-lateral rim of acetabulum.
- Often associated with deep acetabulum or overly retroverted acetabulum.
*FL and IR causes premature abutment of femur against acetabulum.
What is the position for maximal congruency in non-weight bearing?
FL, ABduction, and slight ER
*This position is utilized in diagnosis of hip dysplasia to improve joint congruency.
Describe the bending moment of hip in regards to structural adaptation to weight bearing.
Half the weight of head, arms, and trunk passes down through pelvis and ground reaction force travels up the shaft.
Creates:
- superiorly: tensile forces
- inferiorly: compressive force
What does the trabecular systems provide?
Structural resistance.
- Strongest where they cross at right angles
- Zone of weakness is where they are thin and do not cross
Describe the hip joint capsule.
Is a substantial contributor to hip joint stability.
Composed of irregular, dense fibrous longitudinal and oblique fibers.
Where is the capsule thickest and thinest?
Thickest anterosuperiorly
Thin and loose posteroinferiorly
Describe the function iliofemoral ligament (y-ligament).
Provides anterior stability to joint and controls IR and ER.
Describe the function of the pubofemoral ligament.
Controls ER in extension.
Describe the function of the ishiofemoral ligament.
Primary restraint to IR.
What happens to all the ligaments with hyperextension?
All of them tighten.
Describe the transverse acetabular ligament.
Protects the blood vessels that travel beneath it to get to the head of the femur.
Describe the acetabular labrum.
Wedge shaped and deepens concavity.
- Acts as a seal to maintain negative intra-articular pressure.
Describe the ligamentum teres.
Traditionally believed to serve only as a conduit for blood supply to the femoral head.
- Excessive ER can strain/potentially tear
What are the osteokinematics of the hip?
Flexion/extension
AB/ADduction
ER/IR
What are the arthrokinematics of the hip during flexion?
Anterior roll and posterior glide
What are the arthrokinematics of the hip during extension?
Posterior roll and anterior glide
What are the arthrokinematics of the hip during abduction?
Superior roll and inferior glide
What are the arthrokinematics of the hip during adduction?
Inferior roll and superior glide
What are the arthrokinematics of the hip during IR?
Anterior roll and posterior glide
What are the arthrokinematics of the hip during ER?
Posterior roll and anterior glide
When weight bearing, where does the motion of the hip occur?
The femur is relatively fixed –> motion occurs by movement of pelvis on femur.
What are the osteokinematics of the pelvis moving on the femur?
Anterior/Posterior pelvic tilt
Lateral tilt
Forward/Backward rotation
What does an anterior and posterior tilt of the pelvis produce at the hip?
Anterior tiliting = produces hip FL
Posterior tiliting = produces hip EX
Describe the arthrokinematics (CKC) of an anterior and posterior pelvic tilt.
Anterior tilt = anterior roll, anterior glide
Posterior tilt = posterior roll, posterior glide
Describe the arthrokinematics (CKC) for lateral pelvic tilt.
Abduction = superior roll, superior glide
Adduction = inferior roll, inferior glide
Describe forward rotation of pelvis in CKC.
Side of pelvis opposite to stance leg moves anteriorly –> results in IR of the stance hip joint
Describe backward rotation of the pelvis in CKC.
Side of pelvis opposite to stance leg moves posteriorly –> produces ER of the stance hip joint
Describe the arthrokinematics (CKC) of IR and ER.
IR = anterior roll and anterior glide
ER = posterior roll and posterior glide
What is the closed pack position of the hip?
Full extension with slight IR and abduction
What is the open pack position of the hip?
Moderate flexion, slight abduction, neutral rotation
What is the capsular pattern of the hip?
IR = flexion = abduction
