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Common Orthotics. Thomas Howard, MD 2010. Objectives. Define Orthotics Discuss Common Orthotics Focus on Foot Orthotics Explain importance of Subtalar Joint Review biomechanics of the foot- normal and pathologic Review functional theories of foot orthotics
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Common Orthotics Thomas Howard, MD 2010
Objectives • Define Orthotics • Discuss Common Orthotics • Focus on Foot Orthotics • Explain importance of Subtalar Joint • Review biomechanics of the foot- normal and pathologic • Review functional theories of foot orthotics • Assess foot orthotics role in the prevention and treatment of injury
What is an Orthotic?? Definition: An orthopedic appliance/device designed to correct, straighten or support a body part
How do they work?? • Prevent abnormal motion or movement? • Change mechanics? • Proprioception?
Elbow • Tennis Elbow
Wrist • Cock-up splint • TSS • Carpal tunnel brace
Finger • Stax splint • Dorsal PIP splint
Back • TLSO • Milwaukee brace • Lumbar Corset • Hyperextension Brace • Cervical collar
Knee • ACL/de-rotation brace • MCL brace • Knee sleeve • Cho-pat strap • Single and dual strap
Ankle • Stirrup brace • Short and long • Lace-up brace • ?figure-eight strap • Tri-loc • AFO • Night splint
Foot • Met Pad • Bunion brace • Hammer toe brace • PSC • Arch Brace
What is a Foot Orthotic?? Device used to accommodate foot deformity or pressure lesions, cushion the foot, alter sensory input, or realign foot posture
Terminology Arch support Medial/lateral wedge Insole Heel wedge Metatarsal pad
Types of Orthotics • Prefabricated OTC • Dr. Scholls, Spenco, Hapad • Advantage • Cheap • Convenient • Effective • Disadvantage • Mass produced • Nonspecific arch contour • Fails to address positional/structural deformities and compensations
Types of Orthotics • Biomechanical or Custom • Advantage • Address the source of compensation • Slow rate/extent of deformity • Disadvantage • Cost • Experience of provider • May not help
Accomodative Orthotics • Fit in shoe to stabilize foot deformity • Allows foot to compensate • Transfer weight from painful area • Improves shock absorption • Control ground reactive forces around a specific location • Example: Diabetic foot, Neuropathy, PVD, congenital malformations
Functional or Corrected Orthotic • Addresses patho-mechanical components of the lower extremity/foot/ankle condition • Resists abnormal compensation • Prevent pain during ambulation • Prevent pathologic ROM • Example: athletes, pes planus, pes cavus
Custom: Stiffness • Rigid (pes planus) • control foot function • provide stability • firm material • Semi-rigid (athletes) • dynamic balance of foot • layers of soft/rigid laterial • Soft (pes cavus) • absorb shock • improve balance • remove pressure • compressible material
Materials • Thermoplastic/Polypropylene • EVA (Ethyl vinyl acetate) • Carbon Fiber • Polyethylene Foam (“Plastazote”) • Cellular Urethane (“Poron”) • Graphite
Indications • Support and correct intrinsic deformities • Decrease frequency of lower limb injuries • Control ROM • Improve sensory feedback / proprioception/neuromuscular responses • Dissipate pathologic ground reaction forces and improve shock absorption • Improve LE biomechanics
Evaluation • Chief complaint • Assess mobility (hypo, hyper) • Type of orthotic needed (dress, athletic, street) • Rigidity • Material
Evaluation • Assess ROM, positioning • Test lower quadrant muscle strength • Static stance position and toe rise • Leg length measurement • Gait analysis • Assess position & motion of spine hip/pelvis, knee, lesser metatarsals
How are they made?? • Casting • Impressions • Gait/Balance Analysis
MT cut-out Modifications • Metatarsal (MT) head cut-out • Heel cushioning • Metatarsal pads • Morton’s extension • Rigid forefoot extension Morton’s extension Pad Heel cushioning
How are they made?? No matter which method is done….. Subtalar Joint must be in neutral position
Subtalar Joint • Anatomy: -Talus (superior) -Calcaneus (inferior)
Subtalar Joint • Oblique orientation • Allows for pronation and supination • Motion is tri-planar • Affects motion/flexibility of midtarsal joint and tibia • Controls plantar surface pressure and contact with the ground during gait
SubTalar Joint • Oblique axis: -23 degrees from long axis of foot -41 degrees from horizontal plane
Subtalar Joint • Motion is tri-planar • Pronation • Eversion, abduction, dorsiflexion • Supination • Inversion, adduction, plantarflexion
Midtarsal Joint • Calcaneocuboid • Talonavicular • Motion at STJ • Passes from talus/ calcaneus to navicular and cuboid • Affects flexibility or stiffness of foot
Tibial Rotation • Torque developed by foot movement transmits proximally • 1:1 relationship between degree of • Supination and tibial external rotation • Pronation and tibial internal rotation
Gait Cycle (walk) • Heel Strike (0-15%):pronate • Stance/foot flat (15-30%): pronate to supinate • Push/toe off (30-45%): supinate • Swing (45-60%): supinate to pronate
Heel Strike • Internal rotation of tibia • Inversion of STJ • Eversion of calcaneus
Gait Biomechanics • Heel Strike: Eversion of calcaneus Alignment of mid-tarsal joints (parallel) Allow increased motion/flexible foot Absorb shock/accomodate
Stance Phase • Pronated position holds through 1st 15% of stance; then supination begins • External rotation of tibia • Eversion of STJ • Inversion of calcaneus
Gait Biomechanics • Mid-Stance: Inversion of calcaneus Midtarsal joint axis not parallel Foot becomes more rigid Increased stability
Abnormal Pronation • Add 6° eversion to calcaneal ROM (nl=20°) • Increase ground reaction forces along medial chain • Excess internal rotation of tibia • Muscles work harder to keep balance • Decrease stability during propulsion
Abnormal Supination • Add >12° of calcaneal inversion (nl=10°) • Increased forces along lateral chain • Hypomobility in subtalar joint • Decreased shock-absorbing capability • Decreased stability at heel strike
Subtalar Joint and Orthotics • Position of STJ affects position and function of entire foot • Neutral STJ is the point in the stance phase of gait where joint is not compensated
Subtalar Joint (STJ) and Orthotics • If capture pronated/supinated (compensated) foot for molding orthotic, get contour that reflects and facilitates compensated position • Want orthotic to control STJ motion before it compensates to allow optimal function of joints/muscles
Clinical significance??? • Do abnormal properties of gait lead to clinical pathology?? • Do orthotics change biomechanics of gait?? • If so, have they been proven to prevent injuries??
Messier SP, Pittala KA. MSSE: Oct 1988;20(5):501-5 • Retrospective study • Relationship between biomechanical variables and injury (ITB, shin splints, plantar fasciitis) • Results: -Nonsignificant increase in over-pronation and high- arches in injury group
Willems TM, et al. Gait & Posture 23 (2006):91-98 • Prospective study in freshmen athletes in Belgium • Risk factors for exercise-related lower leg pain (ERLLP) • Gait examined and injuries logged • Results • Overpronation associated with increased incidence of ERLLP