Q1&2: LL Ox Systems, Biomechanics, Recommendations (AFO)

Question 1

4 categories of pathologic gait

Answer 1

1. Structural Impairment
2. Motor Unit Insufficiency
3. Peripheral sensory and motor impairment
4. Central Control Dysfunction

Question 2

Self selected walking speed (Men)

Answer 2

1.43 m/s

Question 3

Self selected walking speed (Women)

Answer 3

1.39 m/s

Question 4

Proper fitting parameters for footwear

Answer 4

• 3/8” to 1/2” distal to toes
• adequate depth to accommodate foot
• heel counter captures and suspends calcaneus

Question 5

Imposed Impairment (ankle fusion)

Answer 5

Walking speed decreases by 84% and increases work expenditure by 3%

Question 6

Imposed Impairment (knee immobilization)

Answer 6

Walking speed decreases and increases work expenditure by 33%
- adding a lift to contralateral side can cut this in half

Question 7

Imposed Impairment (hip fusion)

Answer 7

Walking speed decreases by 84% and increases work expenditure by 32%

Question 8

Ankle Joint Control [PERLS]

Answer 8

Permit free motion (in one plane)
Enhance desired motion (assist)
Resist undesired motion (resist)
Limit motion (to a specific range/adjustable)
Stop motion (lock)

Question 9

AFO Trimlines (Solid)

Answer 9

anterior to malleolus

Question 10

AFO Trimlines (Semirigid)

Answer 10

Bisect the apex of the malleolus

Question 11

AFO Trimlines (Flexible)

Answer 11

Posterior to malleolus

Question 12

AFO Trimlines (Posterior Leaf Spring)

Answer 12

Further posterior than flexible trimline

Question 13

Owen’s Criteria for Articulation

Answer 13

1. adequate PROM for ankle DF (10 degrees)
2. minimal spasticity (2/5 max.)
3. adequate strength to enable volitional control (min. 3/5 PF MMT)

Question 14

Ankle joint options - Free Motion (Tamarack)

Answer 14

Robust design as compared to Gillette, tolerates alignment inconsistency, easily swapped out
has DF assist option

Question 15

Ankle joint options - Free Motion (Gaffney)

Answer 15

more durable but increased weight; requires precise alignment for smooth articulation

Question 16

Ankle joint options - Free Motion (Oklahoma)

Answer 16

More robust than a tamarack and effective in high activity users, Easily Swapped out;
Potentially bulky, difficult to adjust in patients with impingement issues

Question 17

Ankle joint options - Intrinsic Stop (Camber Axis)

Answer 17

Uses small interchangeable alloy cams to limit sagittal plane motion; Requires precise alignment

Question 18

Ankle joint options - Intrinsic Stop (Clevisphere)

Answer 18

Features an adjustable plantarflexion stop which can be revised by tightening a set screw

Designed to accommodate tibial torsion
Most individuals medial malleolus is anterior to the lateral malleolus

Question 19

Ankle joint options - Motion Assist (Tamarack)

Answer 19

Available in adult and pediatric sizes; Different durometers to achieve different degrees of DF assist
- 75 (original), 85, 95 durometer

Question 20

Design Considerations - Plantar Stop

Answer 20

Effective for plantar flexor spasticity or absent
dorsiflexor muscle group

Question 21

Design Considerations - Dorsi Stop

Answer 21

Effective for absent plantar flexor muscle group and/or
weak quadriceps

Question 22

Design Considerations - Free Motion

Answer 22

Patients requiring only coronal plane support (tibialis
posterior dysfunction, early stage 3)

Question 23

Design Considerations - Dorsiflexion assist

Answer 23

must be used in conjunction with plantar stop
unless patient has normal plantarflexor tone

Question 24

Double Action Ankle Joints

Answer 24

• Provide considerable adjustability
• Potentially heavy
• Bulky Design
• Allows for joint to change as patients presentation does
• Joint Configuration Options

Question 25

ADR Joint

Answer 25

- “The Swiss Army Knife of Ankle Joints” * DAAJ with double the channels (Quadruple Action?!) - Allows Stops, Resists/Assists for PF & DF * 240 Inch/Lbs DF Assist * 360 Inch/Lbs PF Assist - Allows comparable adjustability to endoskeletal components for prosthetics -> Limited to the sagittal plane

Question 26

AFO Trimlines to address pronation/supination

Answer 26

Pronation - medial flange Supination - lateral flange *extrinisic heel post can accommodate flexible deformities *could also incorporate a T-strap if fixed

Question 27

Floor Reaction AFOs

Answer 27

Rigid, laminated AFO in slight plantar flexion * Extended to mid-patella * External extension moment resists knee flexion

Question 28

Fitting Guidelines for AFOs (adults)

Answer 28

- Proximal Trimline - 20mm distal to the neck of the fibula - Chaffe - D-Ring should sit at least ½” (12mm) from the prox. & ant. edge - Anterior opening Project anteriorly at muscle belly Project proximal to desired ankle trimline - Midfoot Encapsulate shafts of 1st – 5th metatarsals Fully encapsulate navicular medially Fully encapsulate base of the 5th laterally - Forefoot Terminate proximal to the 1st and 5th metatarsal

Question 29

Fitting Guidelines for AFOs (pediatrics)

Answer 29

Leave proximal trimline as close to neck of fibula as possible and leave footplate long as possible to accommodate growth; Wrap trimlines anterior at the calf and dorsal to the foot to increase surface area and triplanar control (requires flexible materials)