732 Lower Extremity Alignment

center edge angle

the extent to which the acetabulum covers the femoral head within the frontal plane

center edge angle normal adult angle

35°

what does a decreased/smaller center edge angle mean

• decreased acetabular coverage

• less bony congruence

• potentially greater range of motion

• increase stress on other tissues

what does an increased/larger center edge angle mean

• increased acetabular coverage

• more bony congruence

• impingement going into abduction

• more stability

acetabular anteversion angle

the extent to which the acetabulum surrounds the femoral head within the horizontal plane

what is the acetabular anteversion angle in a normal adult

20°

acetabular excessive anteversion

greater than 20°

acetabular retroversion

less than 20°

what does acetabular excessive anteversion lead to

• decreased joint coverage anteriorly

• more ROM in IR/ER

what does acetabular retroversion lead to

• increased joint coverage anteriorly

• more bony congruence

• less ROM in IR/ER

what do center edge angle and acetabular anteversion both measure

the shape of the acetabulum

angle of inclination

the angle within the frontal plane between the femoral neck and the medial side of the femoral shaft

angle of inclination infant normative value

165-170°

angle of inclination normative value in adults

125°

what is coxa vara

an angle of inclination less than 125°

advantages to coxa vara

• increased moment arm for hip abductor force

• improved joint stability

disadvantages to coxa vara

• changes in force across the neck of the femur

• decreased functional length of hip abductor muscles

changes in force with coxa vara

• increased bending forces through the neck of the femur

• increased shear forces through the neck of the femur

• decreased axial forces through the shaft of the femur

what is coxa valga

an angle of inclination greater than 125°

advantages to coxa valga

• changes in force across the neck of the femur

• increased functional length of hip abductor muscles

disadvantages to coxa valga

• decreased moment arm for abductor force

• joint stability may be decreased

changes in force with coxa valga

• decreased bending forces through the neck of the femur

• decreased shear forces through the neck of the femur

• increased axial forces through the shaft of the femur

femoral torsion

describes the relative rotation that exists between the shaft and the neck of the femur in the transverse plane

femoral torsion normative value in healthy adult

10-15°

femoral torsion infant normative value

40°

femoral torsion excessive anteversion

greater than 15° & femoral head sits in front of condyles in space

femoral torsion retroversion

less than 15° & femoral head sits behind condyles in space

femoral torsion excessive anteversion may be associated with

• congenital dislocation

• marked joint incongruence

• in toeing gait → may lead to contractures of hip IR

what does angle of inclination and femoral torsion both measure

shape of the proximal femur

normal knee alignment

170-175° / 5-10° of valgus

genu valgum

greater than 10° of valgus; knock knees

what does genu valgum lead to

increased tension in tissues on the medial side of the knee, these tissues may become lax over time

genu varum

less than 0° of valgus & bow legged

what does genu varum lead to

increased tension in tissues on the lateral side of the knee

Quadriceps angle (Q-angle)

angle that represents the line of pull of the quadriceps relative to the patella

how is Q angle measured

1) a line connecting the midpoint of the patella and ASIS

2) a line connecting the midpoint of the patella and tibial tuberosity

Q-angle normative value in a healthy adult

13-15°

why is the Q angle important clinically

helps to quantify the relative lateral pull of the quads on the patella because the lateral pull affects the direction of patella tracking during knee flexion and extension

in what plane can you observe genu varum and genu valgum

frontal plane

genu recurvatum

greater than 10° of knee extension

in what plane can you observe genu recurvatum

sagittal plane

what does genu recurvatum lead to

increased tension on tissues on the posterior side of the knee and can increase laxity in these tissues

where does plantarflexion/dorsiflexion occur at the foot and ankle

occurs in the sagittal plane around the M-L axis

where does abduction/adduction occur at the foot and ankle

occurs in the transverse plane around the vertical axis

where does eversion/inversion occur at the foot and ankle

occurs in the frontal plane around the A-P axis

pronation at the foot and ankle

combination of eversion, abduction, and dorsiflexion

supination at the foot and ankle

combination of inversion, adduction, and plantarflexion

tibial torsion

the rotation of the tibia on its longitudinal axis causing the low leg to rotate inward or outward

pes planus

low or flat arch

pes cavus

high arch

rigid pes planus

still flat feet in non-weight bearing position

flexible pes planus

arch is flat in weight-bearing and arched in non-weight-bearing

rigid pes cavus

leads to increased stress on the metatarsal head and is less able to absorb forces