Measurement of Dorsal Mobility in the First Ray: Elimination of Fat Pad Compression as a Variable

Abstract

Previous designs for a device to measure first ray mobility have included compression of the first metatarsal fat pad as part of the measurement of displacement or have failed to standardize the force applied to the head of the first metatarsal. In this investigation, assessment of vertical mobility of the first ray of both feet in 14 volunteers was determined using a device that applied dorsiflexing force to the first metatarsal. First ray displacement was measured initially from the plantar surface and then from the dorsal aspect of the head of the first metatarsal. The difference between plantar- and dorsal-surface-measured vertical displacement was highly significant. This study suggests that mobility of the first ray measured from the dorsal aspect of the first metatarsal head eliminated compression of the plantar fat pad from being interpreted as part of the measurement of displacement.

Criterion-Related Validity of a Clinical Measure of Dorsal First Ray Mobility

“…Measurements of dorsal mobility in clinical populations typically range from 4 to 8 mm. 3,4,5 Measures recorded with the device were reliable, with an ICC equal to 0.98 and a SEM equal to 0.15 mm. An ICC gives comparison of 2 or more repeat measures.…”

“…Adding further error to the measurement, the ruler set compressed into the dorsum of the foot. 5 A limitation of the study was that subjects were not current patients. It seems reasonable, however, to conclude that the properties of measurement associated with the ruler technique would not improve in a clinical setting where acute pain, swelling, and deformity are commonly seen.…”

“…12 A single examiner measured first ray dorsal mobility with the device (Figure 2). [3][4][5][6][7][8] The examiner (W.M.G.) operating the device was blinded from the results made with the rulers.…”

“…The device and protocol for testing are described elsewhere. [3][4][5][6][7][8] Measurements made with the device have been found to be reliable (ICCՆ 0.92; SEM Յ 0.35 mm), [3][4][5][6][7] and valid (ICC = 0.97), as judged by concurrent movement of the first ray as assessed with radiographs. 8 The device imposes a dorsiflexion force from beneath the first metatarsal head while measuring dorsal mobility of the first ray.…”

The first tarsometatarsal joint and its association with hallux valgus

“…Several studies have debated whether motion at the tarsometatarsal joint exist. 15-19 Nevertheless, any movement permitted at the first tarsometatarsal joint is amplified by the long metatarsal shaft. 19 There is very little literature examining the anatomy of the -proximal metatarsal articular surface and its relation to hallux valgus deformity.…”