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FootMaxx™

FootMaxx™

Have pain when walking or running? Let the trained staff at JOI Rehabilitation assess your gait pattern and design custom orthotics to fit your individual needs! Watch the video below to see how the Footmaxx Metascan system works.

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Basic Biomechanics

Biomechanics is the study of the body in motion. Foot biomechanics studies the relationship of the foot to the lower leg. During walking and running the musculoskeletal system generates forces to propel the body forward. The foot serves two main functions. It acts as a mobile adaptor to adjust to varying terrain, and as a rigid lever for forward propulsion in locomotion. The two functions are time specific in that when the foot spends too much time being a mobile adaptor it is not spending enough time being a rigid lever and vice versa. Biomechanics of the foot analyzes how the various structures of the foot, work together to perform specific functions (timing being of utmost importance.) Excessive or prolonged motion or lack of motion will cause various deformities and pathologies discussed in the next section. Proper biomechanics allow human beings to walk, run, jump, and move freely without pain or dysfunction.

The following are important terms used frequently in the study of the biomechanics of the foot:

1. Gait Cycle (see Figure 2.5)- a complete gait cycle when the foot is in contact with the ground (weight bearing)

2. Stance Phase (see Figure 2.6)– A portion of the gait cycle when the foot is in contact with the ground (weight bearing)

3. Swing phase- the portion of the gait cycle when the foot is in the air (non-weight bearing)

4. Subtalar joint– neutral position- the position of the subtalar joint in which the foot is neither pronated nor supinated. When the hindfoot is neutral, the bisector of the calcaneus is the 90 to the supporting surface.

Picture of supinated foot position on left, neutral foot position in center, and pronated foot position on right

Picture of 3 types of foot biomechanical movements

5. Subtalar joint pronation- is a coordinated triplane motion of the foot which involves three planes of motion: abduction, dorsiflexion and eversion.

Picture of pronation of foot

Pronation of foot

6. Subtalar joint supination– a coordinated triplane motion of the foot which involves three planes of motion: adduction, plantarflexion and inversion

Picture of supination of foot

Supination of foot

7. Pronated and supinated– adjectives which describe the position of the foot (they do not describe the action of pronation or supination). Thus a “pronated foot” is one which is in a pronated position as compared to a neutral position.

8. Degrees of pronation and/or supination- this is measured by the degrees of inversion (in the case of supination) or eversion (in the case of pronation) away from the neutral position.

9. Normal centre of pressure line (gait line)- is the average vector of all forces that act on the bottom of the normal foot as it goes through the stance phase of gait. Figure 2.5 shows the progression of the forces in the “Normal centre of pressure line” as the foot goes from contact phase to propulsion.

Picture of center of pressure through foot with gait phases

Center of pressure of foot with gait

Interpreting the Center of Pressure Line

Picture of short heel center of pressure in foot

Short Heel

Short (heel through mid-foot)
Metatarsalgia • Dropped metatarsal head(s) • Sesamoiditis • Hyper-lordosis

Accommodations: 1st ray cut-out, met bar, met pad
Suggested Orthotics: Sulcus-length Dress, Pro-Baseball, Allsport

Normal center of pressure (COP) line shown in red.
Deviated COP line shown in black.


Picture of straight center of pressure in foot

Straight

Straight (medial deviation)
Forefoot hypermobility • Calcaneal eversion • Plantar fascia strain • Knee, hip, low back pain

Suggested Orthotics: Dress, Pro-Baseball, Pro-Marathoner

Normal center of pressure (COP) line shown in red.
Deviated COP line shown in black.


Picture of late center of pressure in foot

Late

Late (midfoot through metatarsals)
Achilles tendonitis • Tight calf muscles • Heel spur/plantar fasciitis • Kyphosis

Accommodations: Heelmaxx™, heel lift, soft arch strips
Suggested Orthotics: Dress, Pro-Marathoner, Marathoner

Normal center of pressure (COP) line shown in red.
Deviated COP line shown in black.


Picture of heel instability center of pressure in foot

Heel instability

Heel Instability
Ankle instability • Pelvic rotation • Rearfoot varus

Accommodations: Heel lift
Suggested Orthotics: Dress, Pro-Marathoner

Normal center of pressure (COP) line shown in red.
Deviated COP line shown in black.


Picture of midfoot instability center of pressure in foot

Midfoot instability

Mid-foot Instability
Arch elongation • Fascial strain • Flexible plantarflexed 1st ray

Accommodations: Soft arch strips
Suggested Orthotics: Dress, Pro-Crosstrainer, Pro-Marathoner

Normal center of pressure (COP) line shown in red.
Deviated COP line shown in black.


Picture of forefoot instability center of pressure in foot

Forefoot instability

Forefoot Instability
Knee strain (patellofemoral, ilio tibial strain) • Metatarsal instability
Hallux limitus • Anterior/posterior tibial strain

Accommodations: Soft arch strip/fill, heel lift, met pad
Suggested Orthotics: Dress, Pro-Marathoner, Marathoner

Normal center of pressure (COP) line shown in red.
Deviated COP line shown in black.


Picture of forefoot instability with torque center of pressure in foot

Forefoot instability with torque

Forefoot Instability with Torque
Knee instability • Trauma to the knee • Hallux limitus

Accommodations: Soft arch strip/fill, heel lift
Suggested Orthotics: Dress, Pro-Crosstrainer, Pro-Marathoner

Normal center of pressure (COP) line shown in red.
Deviated COP line shown in black.


Picture of complete instability center of pressure in foot

Complete instability

Complete Instability
Instability in gait (geriatric population, MS patients)
Knee instability • Hypermobile midtarsal joint

Accommodations: Soft arch strips/fills
Suggested Orthotics: Dress, Pro-Crosstrainer, Arthritic 2

Normal center of pressure (COP) line shown in red.
Deviated COP line shown in black.

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