Pilot Study: Effect of Morton’s Extension on the Subtalar Joint Forces in Subjects with Excessive Foot Pronation

Abstract

This study focuses on the assessment of the mechanical effect produced by Morton’s extension as an orthopedic intervention in patients with bilateral foot pronation posture, through a variation in hindfoot and forefoot prone-supinator forces during the stance phase of gait. A quasi-experimental and transversal research was designed comparing three conditions: barefoot (A); wearing footwear with a 3 mm EVA flat insole (B); and wearing a 3 mm EVA flat insole with a 3 mm thick Morton’s extension (C), with respect to the force or time relational to the maximum time of supination or pronation of the subtalar joint (STJ) using a Bertec force plate. Morton’s extension did not show significant differences in the moment during the gait phase in which the maximum pronation force of the STJ is produced, nor in the magnitude of the force, although it decreased. The maximum force of supination increased significantly and was advanced in time. The use of Morton’s extension seems to decrease the maximum force of pronation and increase supination of the subtalar joint. As such, it could be used to improve the biomechanical effects of foot orthoses to control excessive pronation.

Orthopaedic Simulation of a Morton’s Extension to Test the Effect on Plantar Pressures of Each Metatarsal Head in Patients without Deformity: A Pre-Post-Test Study

“…Adhering to a consistent protocol administered by the same specialist across all study participants, a 5-mm EVA Morton's extension was uniformly affixed from the first metatarsal head to the proximal phalanx of the hallux [15]. A paper bandage secured this component in place [27].…”

“…The exclusion criteria of subjects were: (1) plantar corns and calluses, (2) hallux valgus and lesser toe deformities, (3) diabetes, and (4) lower limb dysfunction [15].…”

“…However, limited studies have investigated the effects of orthopaedic devices on plantar pressures using the Morton's extension device. Morton's extension, an element positioned beneath the anterior part of the foot orthosis under the first ray, extends from the first metatarsal head to the proximal phalanx of the hallux [15]. Constructed from a firm or rigid orthopaedic material, the Morton's extension extends below the great toe, aiding in the reduction of the dorsiflexed position of the first ray in the sagittal plane [15].…”

“…Morton's extension, an element positioned beneath the anterior part of the foot orthosis under the first ray, extends from the first metatarsal head to the proximal phalanx of the hallux [15]. Constructed from a firm or rigid orthopaedic material, the Morton's extension extends below the great toe, aiding in the reduction of the dorsiflexed position of the first ray in the sagittal plane [15]. Proper dorsiflexion movement of the metatarsophalangeal joint during motion is essential for stabilising the foot in the final contact phase of gait and ensuring effectiveness [16].…”

Effects of Myofascial Induction Therapy on Ankle Range of Motion and Pressure Pain Threshold in Trigger Points of the Gastrocnemius—A Clinical Trial

“…Exclusion criteria for the study consisted of several parameters: (1) Diagnosis of lower limb injury, including any tendinopathy, bursitis, ligamentous involvement, and/or fasciitis [25]; (2) history of lower limb surgery or history of lower-extremity injury with residual symptoms (pain or feeling of sensations) within the last year [26]; (3) participants could not have undergone ankle stretching or any other treatment [21]; (4) diabetes due to possible alteration of arterial distal circulation [28]; (5) foot deformity, cavus, and flat feet; (6) two deformities, such as hammer toes and hallux valgus, ( 7) plantar corns and calluses, and/or (7) lower limb dysfunction or chronic injury [29].…”