Q1&2: LL Ox Systems, Biomechanics, Recommendations (AFO) Flashcards
4 categories of pathologic gait
- Structural Impairment
- Motor Unit Insufficiency
- Peripheral sensory and motor impairment
- Central Control Dysfunction
Self selected walking speed (Men)
1.43 m/s
Self selected walking speed (Women)
1.39 m/s
Proper fitting parameters for footwear
- 3/8” to 1/2” distal to toes
- adequate depth to accommodate foot
- heel counter captures and suspends calcaneus
Imposed Impairment (ankle fusion)
Walking speed decreases by 84% and increases work expenditure by 3%
Imposed Impairment (knee immobilization)
Walking speed decreases and increases work expenditure by 33%
- adding a lift to contralateral side can cut this in half
Imposed Impairment (hip fusion)
Walking speed decreases by 84% and increases work expenditure by 32%
Ankle Joint Control [PERLS]
Permit free motion (in one plane)
Enhance desired motion (assist)
Resist undesired motion (resist)
Limit motion (to a specific range/adjustable)
Stop motion (lock)
AFO Trimlines (Solid)
anterior to malleolus
AFO Trimlines (Semirigid)
Bisect the apex of the malleolus
AFO Trimlines (Flexible)
Posterior to malleolus
AFO Trimlines (Posterior Leaf Spring)
Further posterior than flexible trimline
Owen’s Criteria for Articulation
- adequate PROM for ankle DF (10 degrees)
- minimal spasticity (2/5 max.)
- adequate strength to enable volitional control (min. 3/5 PF MMT)
Ankle joint options - Free Motion (Tamarack)
Robust design as compared to Gillette, tolerates alignment inconsistency, easily swapped out
has DF assist option
Ankle joint options - Free Motion (Gaffney)
more durable but increased weight; requires precise alignment for smooth articulation
Ankle joint options - Free Motion (Oklahoma)
More robust than a tamarack and effective in high activity users, Easily Swapped out;
Potentially bulky, difficult to adjust in patients with impingement issues
Ankle joint options - Intrinsic Stop (Camber Axis)
Uses small interchangeable alloy cams to limit sagittal plane motion; Requires precise alignment
Ankle joint options - Intrinsic Stop (Clevisphere)
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
Ankle joint options - Motion Assist (Tamarack)
Available in adult and pediatric sizes; Different durometers to achieve different degrees of DF assist
- 75 (original), 85, 95 durometer
Design Considerations - Plantar Stop
Effective for plantar flexor spasticity or absent
dorsiflexor muscle group
Design Considerations - Dorsi Stop
Effective for absent plantar flexor muscle group and/or
weak quadriceps
Design Considerations - Free Motion
Patients requiring only coronal plane support (tibialis
posterior dysfunction, early stage 3)
Design Considerations - Dorsiflexion assist
must be used in conjunction with plantar stop
unless patient has normal plantarflexor tone
Double Action Ankle Joints
- Provide considerable adjustability
- Potentially heavy
- Bulky Design
- Allows for joint to change as patients presentation does
- Joint Configuration Options
ADR Joint
- “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
AFO Trimlines to address pronation/supination
Pronation - medial flange
Supination - lateral flange
*extrinisic heel post can accommodate flexible deformities
*could also incorporate a T-strap if fixed
Floor Reaction AFOs
Rigid, laminated AFO in slight plantar flexion
* Extended to mid-patella
* External extension moment resists knee flexion
Fitting Guidelines for AFOs (adults)
- 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
Fitting Guidelines for AFOs (pediatrics)
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)