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Flashcards in Arthrodesis Man Deck (14)
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1

Outline of arthrodesis Man

2

What is elastrohydrodynamic lubrication?

Primary lubrication mechanism for articular cartilage during dynamic function

3

What is the normal hip range of motion?

4

Hip Biomechanic Pearls

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

5

Hip Joint Arthrodesis:

24-30 degrees of flexion

0 abduction

0 rotation

 

increases o2 consumption

decrease gait efficiency by 50%

6

Knee joint Biomechanics

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.

7

Arthrodesis of the knee joint

10-15 degrees flexion

0-7 degrees valgus

neutral rotation

 

8

Ankle arthrodesis:

Neutral Dorsiflexion

5-10 degrees external rotation

5 degrees hindfoot valgus

 

70% loss of saggital motion in the foot. 

9

Foot Biomechanics

1st metatarsal bears most of the load during standing

2nd metatarsal carries the most load with gait. 

 

3 Arches:

    Medial longitudinal

    lateral logitudinal

    Transverse

10

What is the motion segment of the spine?

two vertebrae and the intervening soft tissue 

11

Shoulder Arthrodesis

Flexion-20-25

Abduction-10-15

Internal Rotation- 45 degrees

 

Hand to mouth

 

12

Elbow Arthrodesis

90 degrees of flexion if unilateral

 

65 and 110 if bilateral

 

hand to mouth/hand to ass

13

Wrist arthrodesis

10-20 degrees of dorsiflexion

 

max grip strength

 

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

14