Lower Limb Orthoses to Enhance Ambulation OBJECTIVES OBJECTIVES Role of Orthoses in the ... PDF
Preview Lower Limb Orthoses to Enhance Ambulation OBJECTIVES OBJECTIVES Role of Orthoses in the ...
3/3/2015 OBJECTIVES • Discuss the principles used in designing Lower Limb Orthoses orthotic interventions for the lower extremity to restore mobility and function to Enhance Ambulation • Identify orthotic components and relate their function and use to patient criteria • Analyze the effect of orthoseson joint motion Ann Yamane, M.Ed., CO/LO based on biomechanical needs during University of Washington ambulation Division of Prosthetics & Orthotics Role of Orthoses in the OBJECTIVES Rehabilitation Process • Identify indications for use of specific orthosis designs based on goals related to • Provide safe and efficient ambulation to –functional ambulation, access surroundings –protection, • Maximize function –and contractures • Reduce long term effects of skeletal mal‐ alignment 1 3/3/2015 Patient Assessment Biomechanical Principles The assessment aids in determining • Three‐point force systems the biomechanical forces necessary to • Ground reaction force force vectors provide: • Stable skeletal alignment • Alignment • Stable base of support to facilitate –Tibialangle to floor safe ambulation –AFO/Footwear Combination (AFO‐FC) • Substitute for impaired muscle strength • Control unwanted motion from spasticity 3‐Point Force System 3‐Point Force Systems Subtalar Eversion Control • Corrective Forces Sustentaculumtali – Proximal to medial modification malleolus – Sustentaculumtali • Counteractive Forces – Proximal lateral calf – Distal lateral calcaneus Courtesy of Martin Carlson, CPO 2 3/3/2015 3‐Point Force System Subtalar Eversion Control Describe the 3‐point force system used to control excessive plantarflexion in a • Corrective Force thermoplastic AFO? – Proximal to medial malleolus a. posterior calf, plantar surface of the foot at the MT – Sustentaculum tali head region, ankle strap • Counteractive b. posterior calf, dorsum of the foot, anterior calf Forces c. anterior calf, posterior calcaneus, dorsum of the – Proximal lateral foot calf d. proximal lateral calf, medial malleolus, lateral – Distal lateral calcaneus calcaneus Ground Reaction Force Vectors Tibial Angle to Floor • Distal 1/3 of tibia/fibula to floor • Considerations – Ankle joint ROM – Heel height of shoe Perry, J. Gait Analysis, 2010 3 3/3/2015 Tibial Angle to Floor AFO‐Footwear Combination • Shank vertical angle While wearing shoes – Line of shank is along anterior tibial crest in • Heel height relationship to vertical – Differential from the ball of the – Measurement taken foot to the heel with shoe • Heel wedges may be used in – Evaluate overall postural the shoe to accommodate a alignment plantarflexioncontracture Courtesy of Elaine Owen Anatomy of an AFO Anatomy of a Thermoplastic AFO • Stirrup • Foot plate • Soleplate – Length • Sidebar/ • Trim lines Upright – Rigidity through • Calf band position of trim lines at • Pretibial ankle region shell 4 3/3/2015 Plantarflexion Stop Ankle Joint Controls • Tilts the tibia anterior Double Adjustable / Dual and positions the ankle Channel ankle joint joint in dorsiflexion • Plantarflexionstop • Function Ant Post – Pin placed in the –Provide clearance posterior channel during swing phase A Post • Dorsiflexion stop –Produce a knee – Pin placed in the flexion moment at anterior channel loading response Dorsiflexion Stop Dorsiflexion Weakness AFO with a Plantarflexion (PF) Stop • Limits dorsiflexion or • Provides stability in the tibialadvancement sagittal plane by controlling • Function ankle PF during swing phase –Create a knee • Relationship between extension moment A Post – adequate clearance midstancethrough during swing phase terminal stance – knee flexion stability during loading response 5 3/3/2015 An ankle‐foot orthosis with a plantarflexion stop Plantarflexion Weakness positioned in dorsiflexion will induce a/an AFO with a Dorsiflexion Stop • Provides stability in the sagittal a. decreased knee flexion moment. plane by controlling tibial advancement during midstance b. increased knee extension moment. and terminal stance c. increased knee flexion moment. • Relationship between d. increased hip extension moment. – adequate clearance during swing phase – knee stability during stance phase Ankle Joint Controls Ankle Joint Controls Ankle joint with a spring in Double Adjustable / Dual the posterior channel Channel • allows PF ROM at • Spring placed in the loading response posterior channel to A P • provides increased knee allow controlled PF at stability at loading loading response response by decreasing • Pin placed in the the knee flexion anterior channel for a moment DF stop 6 3/3/2015 Ankle Joint Controls Posterior Leaf Spring AFO Dorsiflexion Assist Functions: • allow controlled plantarflexion at loading response and • dorsiflexion ROM during late midstanceand terminal stance Posterior Leaf Spring AFO Carbon AFO Designs Indications: • Dorsiflexion weakness • Varied designs • Minimal need for stability of subtalarand midtarsal – Similar to Posterior Leaf spring joints – Rigid limiting Biomechanical goal: dorsiflexion and • Limit unwanted plantarflexionROM during swing plantarflexion phase – Prefabricated 7 3/3/2015 Ankle Foot Orthoses Case Scenario‐Hx of Polio Custom fabricated – Polypropylene – Laminated – Carbon – Hybrid Biomechanical goals: • DF during swing phase • Stance phase stability Case Scenario‐Hx of Polio Case Scenario‐Polio Custom fabricated carbon Clinical Considerations: AFO • Knee strength • Rigidity/flexibility • Activity level, function • Ankle • Leg length discrepancy • Metatarsal heads • PF contracture 8 3/3/2015 Lower Limb Orthoses Lower Limb Orthoses For Ambulation Categories based on Purpose • Ambulation • Accommodative Foot Orthoses –To improve mobility and independence – Accommodate alignment • Protection and deformities –Protect or prevent further deformity – Lower durometer materials • Contractures –Reduce or prevent limitation of range of motion Lower Limb Orthoses Lower Limb Orthoses For Ambulation For Ambulation • Biomechanical Foot UCBL FO Orthoses • (UC Biomechanics Lab Foot Orthosis) – Coronal plane alignment control • Indications: – Subtalarand midtarsal – Midtarsal pronation/supination, joint control forefoot abduction/adduction • Biomechanical goals: – Control of midtarsaland transtarsaljoints 9 3/3/2015 AFO Function Dorsiflexion Weakness Clearance during Swing Phase • Clinical Observations –Absent heel strike if weakness <3/5 • Indications –Adequate clearance during swing, foot slap at LR – Inadequate DF strength with 3/5 • Design Options –Clearance of the foot reduced during swing phase – DF assist –Compensation with a steppage gait pattern – PF stop –Instability of the subtalar joint Dorsiflexion Assist AFO Case Scenario‐CMT • Clinical Considerations: MMT: – DF ROM of the ankle • Weak DF, PF joint since the design allows DF ROM • Good knee and midstance to terminal hip stance Biomechanical – Allows PF ROM at goals: loading response • Clearance during – Stability of the subtalar, midtarsal, and swing phase transtarsal joints • Subtalarjoint control 10
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