Common Orthotics

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Common Orthotics

• Thomas Howard, MD

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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

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What is an Orthotic??

• Definition An orthopedic appliance/device
  designed to correct, straighten or support a body
  part

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How do they work??

• Prevent abnormal motion or movement?
• Change mechanics?
• Proprioception?

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Elbow

• Tennis Elbow

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Wrist

• Cock-up splint
• TSS
• Carpal tunnel brace

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Finger

• Stax splint
• Dorsal PIP splint

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Back

• TLSO
• Milwaukee brace
• Lumbar Corset
• Hyperextension Brace
• Cervical collar

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Knee

• ACL/de-rotation brace
• MCL brace
• Knee sleeve
• Cho-pat strap
• Single and dual strap

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Ankle

• Stirrup brace
• Short and long
• Lace-up brace
• ?figure-eight strap
• Tri-loc
• AFO

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Foot

• Met Pad
• Bunion brace
• Hammer toe brace
• PSC
• Arch Brace

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Foot Orthotic Basics
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What is a Foot Orthotic??

• Device used to accommodate foot deformity or
  pressure lesions, cushion the foot, alter sensory
  input, or realign foot posture

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Terminology
Arch support
Medial/lateral wedge
Insole
Heel wedge
Metatarsal pad
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Terminology
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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

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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

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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

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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

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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

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Materials

• Thermoplastic/Polypropylene
• EVA (Ethyl vinyl acetate)
• Carbon Fiber
• Polyethylene Foam (Plastazote)
• Cellular Urethane (Poron)
• Graphite

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Indications

• Support and correct intrinsic deformities
• Decrease frequency of lower limb injuries
• Control ROM
• Improve sensory feedback / proprioception/neuromus
  cular responses
• Dissipate pathologic ground reaction forces and
  improve shock absorption
• Improve LE biomechanics

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Evaluation

• Chief complaint
• Assess mobility (hypo, hyper)
• Type of orthotic needed (dress, athletic, street)
• Rigidity
• Material

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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

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How are they made??

• Casting
• Impressions
• Gait/Balance Analysis

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Modifications
MT cut-out

• Metatarsal (MT) head cut-out
• Heel cushioning
• Metatarsal pads
• Mortons extension
• Rigid forefoot extension

Mortons extension
Pad
Heel cushioning
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How are they made??

• No matter which method is done..
• Subtalar Joint must be in neutral position

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Subtalar Joint

• Anatomy
• -Talus
• (superior)
• -Calcaneus (inferior)

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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

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SubTalar Joint

• Oblique axis
• -23 degrees from
• long axis of foot
• -41 degrees from
• horizontal plane

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Subtalar Joint

• Motion is tri-planar
• Pronation
• Eversion, abduction, dorsiflexion
• Supination
• Inversion, adduction, plantarflexion

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Midtarsal Joint

• Calcaneocuboid
• Talonavicular
• Motion at STJ
• Passes from talus/ calcaneus
  to navicular and cuboid
• Affects flexibility or stiffness of foot

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Tibial Rotation

• Torque developed by foot movement transmits
  proximally
• 11 relationship between degree of
• Supination and tibial external rotation
• Pronation and tibial internal rotation

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Gait Biomechanics
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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

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Subtalar Joint Motion
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Heel Strike

• Internal rotation of tibia
• Inversion of STJ
• Eversion of calcaneus

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Gait Biomechanics

• Heel Strike
• Eversion of calcaneus
• Alignment of mid-tarsal joints (parallel)
• Allow increased motion/flexible foot
• Absorb shock/accomodate

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Heel Strike Pronation
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Stance Phase

• Pronated position holds through 1st 15 of
  stance then supination begins
• External rotation of tibia
• Eversion of STJ
• Inversion of calcaneus

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Gait Biomechanics

• Mid-Stance
• Inversion of calcaneus
• Midtarsal joint axis not parallel
• Foot becomes more rigid
• Increased stability

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Stance toe-off Supination
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Abnormal Pronation

• Add 6 eversion to calcaneal ROM (nl20)
• Increase ground reaction forces along medial
  chain
• Excess internal rotation of tibia
• Muscles work harder to keep balance
• Decrease stability during propulsion

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Abnormal Supination

• Add gt12 of calcaneal inversion (nl10)
• Increased forces along lateral chain
• Hypomobility in subtalar joint
• Decreased shock-absorbing capability
• Decreased stability at heel strike

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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

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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

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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??

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Messier SP, Pittala KA. MSSE Oct
198820(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

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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

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Kaufman KR, Brodine SK, et al. Am J Sports Med.
199927(5)585-93

• Prospective study on Navy Seals
• Biomechanics measured prior to training and
  injuries logged over 2 years
• Results
• -Pes planus cavus had 2X incidence of stress
  fracture compared to normal arch

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Simkin A., et al. Foot Ankle. 198910(1)25

• Prospective study of military recruits
• Arches measured and incidence of stress fractures
  recorded
• Femoral/tibial stress fractures higher with high
  arches
• Metatarsal stress fractures higher in low arches

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Increased risk of Stress Fracture/Overuse injury
with Pes Cavus

• Cowan, D., etal. MSSE 1989 21 S60.
• McKenzie, D., et al. Sports Med. 19852 334.
• Messier, S. P, et al. MSSE. 1988 20 501.
• Warren, B. L, et al. MSSE. 1987 19 71.
• Rodgers MM. Phys Ther. 1988 68 1822.
• Chan CW. Mayo Clin Proc. 1994 69 448.

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How do orthotics work??

• Foot orthoses are generally believed to align the
  skeleton and to reduce the loading of biological
  structures in the lower extremities
• but is there evidence??

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Mundermann, Nigg, et al. Clin Biomech. 2003 18
254

• Effects of posting and custom-molding of foot
  orthotics on lower extremity kinematics
• Results
• Molding reduced maximum tibia rotation, foot
  inversion, and foot inversion velocity
• Molding also reduced magnitude of vertical impact
  force
• Results similar by adding medial post

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Eng JJ, Pierrynowski MR. Phys Ther. 199474836.

• Effect of custom foot orthotics on subtalar joint
  and knee joint during walking and running
• Adolescent females with PFPS and measured
  forefoot varus /- calcaneal valgus gt6
• Results
• Subtalar joint rotation reduced 1 to 3 with
  orthotics
• Knee motion reduced in frontal plane during
  walking, not running

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Nester CJ, et al. Gait Posture. 2003 17 180.

• Assess the effect of medially and laterally
  wedged foot orthotics on joint movements
• Healthy subjects
• Results
• Medial wedge
• Decreased rearfoot pronation
• Increased lateral ground reaction force
• Lateral wedge
• Increased rearfoot pronation
• Decreased lateral ground reaction force

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MacLean C, et al. Clin Biomech. 2006 (in press).

• Evaluate influence of custom foot orthotics on
  kinematics in runners
• Healthy runners (normal eversion angles)
• Results
• Statistically significant reduction in rearfoot
  eversion angle in initial stance
• No significant findings at knee joint

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Stacoff A., et al. Clin Biomech. 2000 15 54.

• Effects of medial foot orthotics on skeletal
  movements in running
• Healthy male subjects (no overpronators)
• Results
• -No change in eversion or tibial rotation with
  orthotics

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Ferber R, et al. J Biomech. 2005 38 477.

• Compare joint-coupling patterns (eversion/tibial
  internal rotation) with/without orthotics during
  running
• 11 overpronators measured
• Results
• No difference observed in treated group

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• Can orthotics help prevent and/or treat injury????

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Rome K, et al. Cochrane Database Syst Rev. 2005
Issue 2.

• Evaluated evidence from 10 randomized controlled
  trials of interventions for prevention of stress
  fractures
• All trials involved military recruits and
  shock-absorbing inserts
• Results
• 4 trials showed decrease in stress injuries
• Evidence not consistent on particular design
• Comfort very important

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Gross ML et al. Am J Sports Med. 199119409.

• Questionnaire to runners wearing orthotics for
  various lower extremity complaints
• Predominant insert type was flexible
• Results
• 75.5 found improvement in their condition since
  wearing orthotic
• 90 continued to wear them after symptom
  resolution

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Johnston LB, Gross MT. J Orthop Sports Phys Ther.
200434440.

• Effect of foot orthotics on quality of life in
  those with PFPS who demonstrate excessive
  pronation
• 3 month intervention with orthotics
• Results
• Significant decreases in pain/stiffness after
  only 2 weeks compared to pretreatment evaluation

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Others

• James S., et al. Am J Sp Med. 1978 6 40.
• 78 with knee pain returned to running with
  orthotic use.
• DAmbrosia, et al. Clin Sports Med. 1985 4 611
• Custom orthotics reduce frequency of running
  injuries.
• Donatelli R., et al. J Orthop. Sports Phys. Ther.
  1988 10 205
• Survey showed 96 had pain relief from orthotics
  in treating tibial, knee, and ankle pain
• 70 able to return to activity

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Take home points

• Foot orthotics come in all shapes/sizes and are
  used for a variety of conditions
• When writing prescriptions
• -Know your foot type and activity level
• -Identify trouble spots (for pads, wedges, etc)
• Subtalar joint is an important factor in
  understanding gait biomechanics and keeping in
  neutral controls compensation

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Take home points

• Abnormal biomechanics are proven to increase risk
  for injury
• Still debate over how orthotics actually work
• Still work to be done on effectivenessbut
  comfort is key!!!

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