Biomechanics

Question 1

Kinematics

Answer 1

Study of Motion…not the causes of it! (KineMaticsKM=M[otion])

Question 2

Kinetics

Answer 2

Study of Forces that cause motion.

Question 3

Translation

Answer 3

All parts move through the same distance, at the same time, in parallel paths at equal velocity. Rotation is translation around a joint. If there is no rotation, translation is zero (think of arm hanging straight at side while standing).

Question 4

Traction

Answer 4

The force is used to pull along the long axis for the limb. E.g. the long axis for the GH joint is parallel to the glenoid fossa, or along the length of the arm

Question 5

Distraction

Answer 5

A special case of traction that is perpendicular to the joint surface. Example: pulling the head of the humerus away from the capsule before pulling it inferiorly (traction).

Question 6

Rotation

Answer 6

A special case of translation that occurs around a joint.

Question 7

Osteokinematics:

Answer 7

the motion of bones relative to the three cardinal planes of the body. (Ex. Frontal plane is where lateral flexion, ab-/adduction occur.

Question 8

Arthrokinematics:

Answer 8

describes the motion that occurs between the articular surfaces of joints (ex. Concave convex rule).

Question 9

Do the axes of joint motions fall perpendicular to cardinal planes? Explain

Answer 9

No, they do not. It is only possible with a perfect sphere for the convex part of the joint. All convex members of joints in the body are imperfect spheres with changing surface curvatures.

Question 10

Horizontal (Transverse) Plane

Answer 10

Axial rotation, Internal (medial)/External (lateral) rotation (bisects the body into top and bottom halves).

Question 11

Frontal Plane

Answer 11

Ab-/Adduction, Lateral flexion, Radial/Ulnar deviation, Eversion/Inversion (bisects the body into front and back).

Question 12

Sagittal Plane

Answer 12

(bisects the body into right and left sides) Flexion/Extension, Dorsiflexion/Plantarflexion.

Question 13

What might altar degrees of freedom?

Answer 13

• Pain
• Joint effusion
• Soft tissue tightness

Question 14

Ovoid

Answer 14

convex on concave joint, but in the shape of an egg (imperfect sphere) and an egg cup. Most joints in the body actually fit this description, contributing to their accessory motions that are outside their given planes of movement.

Question 15

Sellar

Answer 15

surface looks convex in one view and concave in another, corresponding surface is the opposite. (Saddle joint)

Question 16

Roll-

Answer 16

each point on the convex surface articulates with a different spot on the concave surface as it moves along

Question 17

Slide-

Answer 17

a single point on the convex surface articulates with different spots on the concave surface as it moves along.

Question 18

Spin-

Answer 18

single point on the convex surface articulates with the single point on the concave surface (ex. A top spinning on one point of the table).

Question 19

Roll is always…

Answer 19

In the direction of skeletal movement.

Question 20

What is the concave/convex rule?

Answer 20

concave moving on convex= roll and slide are in the same direction.
convex moving on concave= the roll and slide are in the opposite direction.

Question 21

What happens if you have roll without slide?

Answer 21

Dislocation

Question 22

What happens if you get slide without roll?

Answer 22

Impingement

Question 23

List 4 ways to classify joint mobility:

Answer 23

• Normal
• Hypermobile
• Hypomobile
• Instability

Question 24

What determines the amount of movement available in the joint?

Answer 24

• Joint structure
• Integrity of joint surface
• Mobility and pliability of soft tissues
• Degree of soft tissue approximation
• Health of surrounding tissue, scarring
• Load- deformation history of the joint
• Age/Gender (range is greatest in infancy and decreases with aging)

Question 25

Normal End Feels:

Answer 25

1. Hard (bony)
2. Firm (capsular, muscle/tendon)
3. Soft (soft tissue approximation)

Question 26

Abnormal End Feels:

Answer 26

1. Empty (pain limited)
2. Springy/springy block
3. Spasm (muscle guarding)
4. Boggy (squishier than you’d expect)
5. Normal end feel found where it shouldn’t be

Question 27

Hypomobility

Answer 27

=restricted motion

• Capsular pattern of restriction= pain and limitation of motion in a predictable pattern to that joint
• Non capsular pattern= maybe derangement, extra-articular problem

Question 28

Closed packed-

Answer 28

tissues stretched, decreasing movements in many directions

Question 29

Open Packed-

Answer 29

tissue loose, increasing movement.

Question 30

Passive insufficiency-

Answer 30

when a 2-joint muscle is too short to perform the normal ROM in the opposite direction at all joints crossed (stretched at one joint but can’t stretch at 2nd joint)

Question 31

Active insufficiency-

Answer 31

muscle cannot generate force due to the shortened state the muscle is positioned in

Question 32

Hypermobility:

Answer 32

over-mobility that is generalized to multiple joints across the body and can be caused by genetic diseases. If it is only at one joint (localized), it can be due to adjacent joint hypomobility.

Question 33

Functional Instability:

Answer 33

disrupted articular/ligamentous structures with functional loss. Key word: Compensation.

Question 34

Anatomical Instability:

Answer 34

no compensation seen and may not have functional loss.