Arthrodesis Man

Question 1

Outline of arthrodesis Man

Answer 1

Question 2

What is elastrohydrodynamic lubrication?

Answer 2

Primary lubrication mechanism for articular cartilage during dynamic function

Question 3

What is the normal hip range of motion?

Answer 3

Question 4

Hip Biomechanic Pearls

Answer 4

Joint reaction force (R) in the hip can reach three to six times body weight (W)–Primarily as a result of contraction of the muscles crossing the hip

Decreases with cane in contralateral hand

Other considerations

Stability-Deep-seated ball-and-socket joint is intrinsically stable.

Sourcil-Condensation of subchondral bone under superomedial acetabulum

R is maximal at this point

Gothic arch-Remodeled bone supporting the acetabular roof; Sourcil at its base

Neck-shaft angle

Varus angulation

Decreases R; Increases shear across the neck

Leads to shortening of the lower extremity

Alters muscle tension resting length of the abductors

May cause a persistent limp

•

Valgus angulation: Increases R/Decreases shear

Neutral or valgus angulation better for THA

PMMA resists shear poorly

Question 5

Hip Joint Arthrodesis:

Answer 5

24-30 degrees of flexion

0 abduction

0 rotation

increases o2 consumption

decrease gait efficiency by 50%

Question 6

Knee joint Biomechanics

Answer 6

ROM 0-130

Functional ROM 0-90

110 degrees-rising from a chair

117-squating/lifting

Knee rotation varies with flexion

no rotation at full extension, but with 90 flexion can rotate 45 degrees ER, 30 degrees IR.

Question 7

Arthrodesis of the knee joint

Answer 7

10-15 degrees flexion

0-7 degrees valgus

neutral rotation

Question 8

Ankle arthrodesis:

Answer 8

Neutral Dorsiflexion

5-10 degrees external rotation

5 degrees hindfoot valgus

70% loss of saggital motion in the foot.

Question 9

Foot Biomechanics

Answer 9

1st metatarsal bears most of the load during standing

2nd metatarsal carries the most load with gait.

3 Arches:

Medial longitudinal

lateral logitudinal

Transverse

Question 10

What is the motion segment of the spine?

Answer 10

two vertebrae and the intervening soft tissue

Question 11

Shoulder Arthrodesis

Answer 11

Flexion-20-25

Abduction-10-15

Internal Rotation- 45 degrees

Hand to mouth

Question 12

Elbow Arthrodesis

Answer 12

90 degrees of flexion if unilateral

65 and 110 if bilateral

hand to mouth/hand to ass

Question 13

Wrist arthrodesis

Answer 13

10-20 degrees of dorsiflexion

max grip strength

if bilateral, then the opposite should be in 10 degrees of palmar flexion