The Reliability and Validity of a First Ray Measurement Device

Abstract

The need for measuring the mobility of the first ray has been identified. The purpose of this study was to test the reliability and validity of a device built to measure the relative vertical displacement of the first ray. Twenty fresh frozen cadaver feet were sampled (mean age of donor was 70+/-13 years). Dorsal mobility of the first ray was measured by device over three trials of repeated loading using 20 N, 35 N, 55 N and 85 N of force. Radiographs served as the criterion standard for validation of the device. Vertical displacement was measured from x-ray by a digitizing procedure that recorded movement of the first ray during loading. Reliability of the device assessed by intraclass correlation coefficients (ICC) was .98 with standard errors of the measurement calculated to be 0.35 mm. A correlation of agreement value of .97 was determined for the two methods of measurement. Analysis of variance testing found a significant interaction between force and method of measurement. Tukey post-hoc analysis found no difference (F<1.70) between the two methods of measuring first ray displacement in cadaver specimens when the force applied did not exceed 55 N. At 85 N of force (F = 10.05), unwanted movement of the second metatarsal caused the device to overestimate the amount of displacement that occurred specific to the first ray. This measure of first ray mobility should help clinicians and researchers to better investigate foot pathology resulting from faulty mechanics of the first ray.

Comparison of dorsal and dorsomedial displacement in evaluation of first ray hypermobility in feet with and without hallux valgus

“…Klaue et al introduced a device that measures dorsal first metatarsal displacement with a numeric value [9]. The validity and reliability of the ''Klaue Device'' has been demonstrated in many studies and has been compared with others methods or radiological investigations [10][11][12][13][14][15][16][17]. Several authors quantify a pathological dorsal hypermobility as a displacement, regardless of the test used, of more than 10 mm [3,9,18,19].…”

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

“…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.…”

“…[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. Force imposed was measured in newtons (N) by a load cell to a maximum load smaller or equal to 55 N. Mobility was measured with 0.01-mm resolution by a linear variable differential transformer.…”

Sonographische Stabilitätsbeurteilung des ersten Metatarsocuneiformgelenks

“…Diese Kraft gilt als notwendig für die Stabilitätsbeurteilung des 1. MC-Gelenks [6,7]. Es wurde mit Hilfe des sonographisch festgelegten Metatarsocuneiformwinkels die Auslenkung im 1.…”

“…MC-Gelenks messen die vertikale Dislokation des ersten Strahls unter gesamter bzw. partieller Vorfußbelastung[5][6][7]10].Rodgers et al maß die vertikale Dislokation des ersten Strahls von plantar aus. Dabei war jedoch die Differenzierung zwischen ossärer Mobilität und Weichteilkompression problematisch [15].…”