Hip B&B + Gait

Question 1

what is the major flexor of the hip joint?

Answer 1

iliopsoas (psoas major + iliacus)

(others: tensor fasciae latae, sartorius, pectinius)

Question 2

what are the major extensors of the hip joint? (2)

Answer 2

1. gluteus maximus
2. hamstrings (semimembranosus + semitendinosus + biceps femoris)

Question 3

what are the major abductors of the hip joint? (2)

Answer 3

1. gluteus medius
2. gluteus minimus

Question 4

what are the major adductors of the hip joint? (3)

Answer 4

1. adductor magnus
2. adductor longus
3. adductor brevis

(others: pectineus, gracillis)

Question 5

what is the major muscle involved in external rotation of the hip joint (knee away from midline, foot toward midline)?

Answer 5

gluteus maximus

(others: obturator internus, gemellus superior/inferior, quadratus femoris)

Question 6

from which nerve roots is the superior gluteal nerve derived?

Answer 6

L4-S1

purely motor, innervates gluteus minimus/medius (abductors) + tensor fasciae latae (flexor)

Question 7

what is Trendelenburg sign? damage to which nerve can cause this?

Answer 7

pelvis tilts with walking because weight bearing leg cannot maintain balance - caused by weak hip abductors

may be due to injury of superior gluteal nerve, which innervates hip abductors

Question 8

what do the superior vs inferior gluteal nerve innervate, respectively? for what type of motion are these muscles required?

Answer 8

superior gluteal nerve: gluteus minimus/medius (hip abductors)

inferior gluteal nerve: gluteus maximus (hip extensor)

Question 9

a patient with a pelvic mass has difficulty standing from a seated position - which nerve is most likely injured?

Answer 9

inferior gluteal nerve: innervates gluteus maximus (major hip extensor)

Question 10

where is avascualar necrosis (osteonecrosis) most common? which artery is affected?

Answer 10

femoral head —> groin pain, difficulty weight bearing

necrosis of bone tissue due to compromise of bone blood vessels, most commonly caused by trauma

femoral head supplied by medial circumflex femoral artery (branch of profunda femoris artery)

Question 11

what is the most feared bone complication of long-term steroid therapy?

Answer 11

avascular necrosis (osteonecrosis) - mechanism not well understood

Question 12

what occurs in slipped capital femoral epiphysis (SCFE)?

Answer 12

fracture through hip growth plate in children, causing slippage of overlying end of femur

—> groin pain on affected side, may cause avascular necrosis

most common hip disorder in adolescence (12-14 yrs)

Question 13

Legg-Calve-Perthes Disease (Perthes Disease)

Answer 13

idiopathic avascular necrosis in children (4-8 yrs)

due to abnormal blood flow to the femoral head, presents as hip pain and limping

Question 14

patient lurching backwards upon heel strike is due to weakness of which muscle?

Answer 14

gluteus maximus - resist the hip being driven into flexion

if gluteus maximus is weak/paralyzed - move line of gravity posterior to hip joint as compensation

Question 15

if patient walks with a hard heel plant and pushes the ipsilateral thigh back with their hand (to extend their knee), which muscle is weak?

Answer 15

quadriceps - resist the knee being forced into flexion

if quads are weak/paralyzed - move knee joint axis behind the line of force (to force its extension) as compensation

Question 16

if patient walks with a hard audible “foot slap,” which muscle is weak?

Answer 16

anterior compartment muscles - tibialis anterior, extensor hallucis longus, extensor digitorum

due to weakness (paralysis = steppage gait)

Question 17

which muscles are weak in a patient with Trendelenburg gait?

Answer 17

unsupported side of pelvis (one with foot off the ground) drops while walking, and patient tilts to move center of gravity to other side

due to weakness of gluteus medius and gluteus minimus - active at time of midstance to prevent gravitational adduction of the pelvis at the hip

Question 18

if patient walks with a lateral leg swing (circumducted gait), which muscles are weak?

Answer 18

fibular (peroneal) muscles (longus and brevis) - innervated by superficial fibular (peroneal) nerve (L5-S2)

normally evert foot… with common fibular nerve injury, have to swing foot to keep bottom of foot parallel to the ground (and prevent landing on inverted side of foot, which would sprain the ankle)

Question 19

if patient walks with “steppage gait” (increased hip/knee flexion, landing with toe strike), which muscles are affected?

Answer 19

paralysis of anterior compartment muscles - tibialis anterior, extensor hallucis longus, extensor digitorum

(weakness = foot slap with heel strike)

Question 20

what is the cause of a foot slap vs steppage gait?

Answer 20

foot slap = weakness of anterior compartment muscles

steppage gait = paralysis of anterior compartment muscles

anterior compartment muscles = tibialis anterior, extensor hallucis longus, extensor digitorum