1. Anatomic and Biomechanical principles related to splinting

2. Anatomic location Arm: area from shoulder to elbow (humerus)
Antecubital fossa: depression at the bend of the elbow
Forearm: area from elbow to wrist
Carpal: wrist or carpal bones
Fingers: thumb, index, middle, ring, little
Numbering fingers: I, II, III, IV, V (thumb)
Palmar = volar: ant aspect of hand and forarm
Radial : thumb side / Ulnar: little finger side

3. Muscles and function nerve supply
Study table 4-4 on page 59

4. Arches of the hand 1. longitudinal arch 2. Distal transverse arch
3. Proximal transverse arch
Functional significance
Never splint the hand flat .. Creates deformity
Specially with tendon and nerve injury

5. Creases of the hand
Three main palmar creases: distal, proximal and thenar creases
The distal palmar crease extends from the fifth MCP joint to a point midway between the second and third MCP joints. This is important for allowing motion of the MCP’s for a wrist immobilization splint

6. Creases of the hand
Important for landmarks when making splint pattern and molding
Figure 4-11
When splinting to immobilize a join, the crease should be included in the splint
When mobilizing a joint?
What happens with:
Edema
Paralysis
disuse

7. Biomechanical principles of splinting
Correct Biomechanics of Splint Design
Splints are simply machines and levers that work together.
Optimal client outcomes rely on biomechanics
Weak muscles are supported, and the pull of stronger muscles is counteracted.
Reduces risk of skin irritation due to pressure
Ultimately may lead to patient comfort, compliance, and function
Splint is an external force acting on the hand

8. Biomechanical principles of splinting
three point pressure
Mechanical advantage (F1*D1 = F2*D2)
Torque
Pressure and stress
1. degree
2. duration
3. repetition
4. direction
Splint is an external force acting on the hand

9. Degree and Duration of Stress
The skin is the least tolerating tissue to stress
Skin becomes ischemic as load increases
Even low stress can cause capillary damage and lead to ischemia
Splints may do that, this is why it is advised to distribute pressure over a larger area of skin

10. Repetitive stress It could lead to inflammation and skin breakdown
You have to remember that some diseases (lymph and vascular involvement) leads to an altered sense of tolerance
Small and sharp edges lead to stress

11. Direction of Stress
You have to remember that there are three directions of stress:
Compression
Tension
Shear
Pressure = Total Force/ Area of force application

12. Questions?