Basic Biomechanics DPT

1. BASIC
BIOMECHANICS
Dr. Zubia Qayyum (PT)

2.  CONTENTS
1.Levers
2. Arthrokinemetics
3. Osteokinemetics
4. Convex-concave rule
5. Joint capsular positions
6. End feel
7. Capsular pattern

3. 1. LEVER
• Levers are simple machines consisting of rigid structures rotating about a
fixed axis.
• It has 3 components
i. Effort/force
ii. Load/resistance
iii. Fulcrum/axis
• By changing the position of fulcrum
Levers are used in 3 mechanical advantages more commonly
Called classes of levers.

4. 1st class levers 2ndclass levers 3rd class levers
Fulcrum lies btw load & effort Load lies btw fulcrum & effort Effort lies btw fulcrum & load
Mechanical advantage=1 Mechanical advantage >1 Mechanical advantage <1
Examples Examples Examples

5. LEVERS OF BODY

6. 2. ARTHROKINEMETICS
• Arthro = joint kinematics= study of motion
• Arthrokinemetics are defined as joint surface
motions, also know as joint play motions and
accessory movements.
• Involuntary
• Necessary for full joint ROM
• Cant be seen, only felt
• Roll  knee
• Glide MCP
• spin radius
• Most of the joints have rolling and gliding simultaneously  ball & socket

7. 3.OSTEO KINEMATICS
• Osteo= bone kinematics= study of motion
• Defines as Movement between 2 bones also known as physiological
movements
• voluntary
• Rotation around the axis in a specific plane
• Clearly visible
• Flexion/extension  sagittal plane
• Abduction/adduction  frontal/coronal plane
• Circumduction  includes all motions
• Need intact accessory movements to complete the ROM

8. 4.CONVEX-CONCAVE RULE
• Convex-concave rule describes relationship between arthrokinematics and
osteokinematics
• Convex rule  When moving joint surface is convex, the roll and glide occur
in the opposite direction.
• Concave rule  When moving joint surface is concave, the roll and glide
occur in the same direction

10. 5.CAPSULAR POSITIONS
Loose pack position Closed pack position
Minimal stress Maximal stress
Lax ligaments Tight ligaments
Separated joint surface Compressed joint surface

11. 6. END FEEL
• Defined as Quality of movement or resistance felt at the end of PROM
• Gives information about Type of structure that limits ROM
Physiological Pathological
1. Soft – soft tissue approximation
e.g. knee flexion
1. Springy --pain causes rebound
2. Firm --muscular, capsular
ligament approximation
e.g. hip flex with straight knee, MCP
extension with supinated forearm
2. Empty --no resistance found due
to pain inhibiting movement before
end range
3. Hard – bony approximation
e.g. Elbow extension
3. Boggy --edema, swelling

12. 7. CAPSULAR PATTERN
• Proposed by Cyrix.
• Defined as Particular pattern of restrictions involving entire joint capsule
caused by pathological conditions.
• Each joint has specific pattern of limitation
• While irritation to structures outside the capsule do not follow same pattern
hence called Non-capsular pattern of movement restrictions
• Classified by Cyrix into 3 categories
i. Ligamentous
ii. Internal derangement
iii. Extra-articular lesion

14. Dr.Zubia Qayyum PT
zubiaqayyum@gmail.com