UNM DPT HIP JOINT KINEMATICS AND PATHOLOGY

Vocabulary flashcards covering key biomechanical principles, pathological conditions, and anatomical structures of the hip joint discussed in the lecture.

where are the tensile forces and compressive forces experienced on the fermur?

Occurs on the superior femoral shaft and inferior femoral neck during weight-bearing, prompting trabecular reinforcement.

what are trabecular systems

Internal bone struts that align along stress lines to resist compressive and tensile forces.

where is the primary weight-bearing area of the femoral head

The superior aspect of the femoral head that contacts the acetabulum during stance.

where is the primary weight-bearing area of the acetabulum

Anterior-superior-posterior lunate surface that accepts femoral head forces.

Contralateral cane use

Placing a cane on the side opposite a painful hip to create a long moment arm that reduces hip abductor demand and joint load.

Pelvic drop (Trendelenburg)

Downward tilt of the swing-side pelvis when stance-side hip abductors are weak or paralyzed.

Compensated Trendelenburg

Lateral trunk lean toward the stance leg to reduce hip abductor torque requirements.

Hip hike mechanics

During right pelvic hike in right stance, left hip abducts, right hip adducts, and lumbar spine side-bends to keep the trunk upright.

Close-packed hip position

Extension with slight abduction and medial rotation that maximally tightens the capsule and ligaments.

Maximally congruent (frog-leg) position

Hip flexion, abduction, and lateral rotation that align articular surfaces most closely.

Open-chain hip motion

Movement when the distal segment (foot) or the pelvis moves freely without obligatory motion at other lower-limb joints.

Closed-chain hip motion

Occurs when both feet bear weight and trunk is fixed and the head is functionally fixed; motion at one joint requires motion at others.

Coxa valga

Increased femoral neck-shaft angle that decreases acetabular coverage and predisposes to dislocation.

Capsuloligamentous laxity

Loose hip capsule and ligaments that lessen joint compression and stability, increasing dislocation risk.

Iliofemoral ligament (lateral band)

Restricts excessive lateral (external) rotation and extension.

Ischiofemoral ligament

Primary restraint to medial (internal) rotation at the hip.

Rectus femoris active insufficiency

Loss of hip flexion power when the knee is fully extended because the biarticular muscle is already shortened.

Hamstring active insufficiency

Weakened hip extension when the knee is flexed due to shortened biarticular hamstrings.

Pelvic forward rotation in unilateral stance

Produces medial rotation of the weight-bearing hip.

Ipsilateral trunk lean for painful hip

Shifts body weight over the affected hip, shortening the external moment arm and decreasing joint force.

Hip position of comfort

Slight flexion, abduction, and lateral rotation adopted reflexively with joint pain to maximize intracapsular volume.

Femoral neck fracture risk factors

Thin trabeculae, cortical bone loss, low bone density, falls, avascular necrosis, and slow shuffling gait.

Femoral head blood supply

Primarily medial and lateral circumflex femoral arteries; secondary supply via ligamentum teres.

Femoral anteversion (medial torsion)

Pathologic inward twisting of the femur causing the femoral neck to face anteriorly relative to condyles.

Adductor-abductor synergy

Co-contraction in bilateral stance to stabilize the pelvis in the frontal plane when abductors are weak.

Acetabular notch

Non-articular inferior gap in the lunate surface bridged by the transverse ligament, allowing vascular passage and load distribution.

Cam impingement

Femoroacetabular impingement subtype caused by an abnormally wide femoral neck that abrades the anterosuperior labrum.

Pincer impingement

Subtype characterized by acetabular overcoverage that compresses the superior labrum, sometimes leading to ossification.

FAI leading to osteoarthritis

Repetitive cam or pincer impingement damages cartilage and labrum, accelerating degenerative joint changes.

Hip joint stability factors

Capsuloligament tension, negative intra-articular pressure, femoral angulation/torsion, intact labrum, and acetabular architecture.

Labral tears from FAI

Cam lesions shear the anterosuperior labrum; pincer lesions crush the superior labrum, often causing bony ossification.