Hip Biomechanics Flashcards
Mobes, glides, Ax/Tx
What are the biomechanic functions of the hip joint?
i) support weight of torso
ii) transfer forces up through pelvis and trunk
What is the hip joint type? (all categories)
i) synovial
ii) simple
iii) ball & socket
iv) unmodified ovoid
v) stability > mobility
What is the pain pattern for osteoarthritis of the hip?
i) proximal inner thigh
ii) anterior thigh
iii) ischial tuberosity
What is the pain pattern for a labral tear at the hip?
i) lateral peritrochanteric area
ii) central groin
What movements does the ilifemoral ligament resist?
Extension (with external rotation).
Which hip ligament(s) blend with the joint capsule?
i) ischiofemoral
ii) pubofemoral
In what position is the ischiofemoral ligament taut?
Extension with full internal rotation. Superior fibres are more taut with adduction, inferior fibres are more taut with hip flexion.
Which movements does the pubofemoral ligament resist?
Extension and abduction.
What is the resting position of the hip joint?
30’ flexion
30’ abduction
slight external rotation
What is the close packed position of the hip joint?
Full extension
Full abduction
Full internal rotation
What is the capsular pattern of the hip joint?
flex > ABD > IR (FABIR)
Describe normal hip joint end feels.
Flexion is soft tissue approximation. All other movements are tissue stretch or capsular.
Describe the biomechanic contributions to hip joint stability in normal standing (ligaments, intra-articular etc.).
In near full hip extension, the COM is posterior to the axis of the hip joint creating an extensor torque. The extracapsular ligamentous complex (especially ilifemoral) passively prevents further extension therefore stabilizing the joint via passive flexor torque. The femoral head is aligned with the thickest part of the articular cartilage therefore protecting the subchondral bone.
Which region of the acetabulum has the thickest articular cartilage?
Anterosuperior region.
Describe the biomechanic consequences of a hip flexed posture in standing.
In flexion, the COM is anterior to the axis of the hip joint therefore creating a flexor torque. The glutes and hamstrings need to prevent further flexion by generating an extensor torque. This increases energy demands and therefore need for rests as well as increases joint forces. There is also increased stress secondary to misalignment of cartilage.
What are three possible ways to address a hip flexed standing posture?
i) hip extension ROM
ii) APT/PPT pelvic stability
iii) Ab strengthening to improve relative PPT.
Which region of the hip experiences arthritic changes first and why?
The anterior aspect of the joint. This is because it is the region of stance phase loading.
What pattern of ROM restrictions would you expect in early osteoarthritis of the hip?
i) decreased extension
ii) decreased internal rotation
How might a patient with early hip osteoarthritis prefer to position their hip (2 options) ?
i) flexed and adducted. AND/OR
ii) extended and abducted
What pattern of ROM restrictions would you expect in late osteoarthritis of the hip?
flex > ABD > IR. May be paired with restricted extension and ER.
What causes ROM restrictions in early osteoarthritis of the hip?
Compensations for pain relief. Ex. reduced stride length and stance time causes reduced extension and internal rotation.
What is the relationship or AROM and PROM in late osteoarthritis of the hip?
The difference between AROM and PROM is much greater in the presence of severe OA.
In what ways does gait change in the presence of hip osteoarthritis?
i) slower (reduced cadence and stride length)
ii) +ve Trendelenberg (or reverse)
iii) Increased APT and frontal plane rotation (compensate for reduced hip extension)
Why might a reverse Trendelenberg be present in hip osteoarthritis?
i) Weak hip abductors.
ii) Loading COM in a position where hip ABDs are at an inefficient length (not being used) reduces mechanical load on the hip and is less painful.
