Pathomechanical changes to rearfoot kinematics, resulting from structural or functional deformities of the foot, can cause considerable alterations in ambulation due to irregularities in biomechanical coordination.
This was successfully demonstrated in a study conducted by Coskun et al. to determine the relationship between hallux valgus deformity and the position of rearfoot joints in 27 patients with the condition.
The authors measured the subtalar angle to determine rearfoot rotation (valgus/varus). This is defined as the angle between the longitudinal line dividing the calcaneus midline and the line that bisects the distal third of the leg.
This can also be defined as the angle between the upper Achilles tendon and the distal extension of the rearfoot in a weightbearing position which can be used to diagnose a normal foot, a physiological flatfoot and a pathological flatfoot.
Based on the findings of the study, the authors observed rearfoot overpronation in the weightbearing position in most of the participants. A correlation was established between increasing hallux valgus angle and aberrant rearfoot kinematics which amplified pain and decreased functionality.
An accurate measurement of rearfoot action relative to tibial motion and forefoot function relative to rearfoot motion can be helpful in gaining more knowledge about the complex interaction between foot joints.
As mentioned by Claudia Angeli, from the Frazier Rehab Institute in Louisville, Kentucky, dynamic loading characteristics can guide the designing of functional orthotics especially to reduce the incidences of overuse injuries in athletes.
This necessitates the use of high-speed three-dimensional kinematic and kinetic data for analysing foot and lower extremity mechanics under dynamic conditions that result in a significant alteration of foot structural integrity, as opposed to static measures.
According to Vivienne Chuter of the Discipline of Podiatry, Faculty of Health at the University of Newcastle in Australia, measurement of the rearfoot involves a combination of transverse and frontal plane assessments including talar head palpation, curvature above and below the malleolus and frontal plane position of the calcaneus.
The author advocates the use of the Foot Posture Index (FPI) as a clinical tool for evaluating dynamic foot function and subsequent predisposition to injury; the FPI has a strong positive relationship with maximum eversion of the rearfoot and can predict 85 percent of the variance in maximum eversion during the stance phase of gait.
A thorough gait assessment can help identify not only the postural abnormality but also the source from where it originates. This enables clinicians to gain as much information about the pathology as possible and to accordingly recommend suitable forms of treatment.
MASS4D® custom foot orthotics offer calcaneal support to control rearfoot pronation and calcaneal eversion angles which can otherwise place higher mechanical demands on the musculoskeletal system and increase the risk of injury.
By making full contact with the plantar surface of the foot, MASS4D® guides the optimal movement of the lower limbs for improvements in gait and balance in addition to supporting re-alignment of the musculoskeletal system for the prevention of overuse injuries.
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