Measurement standards for human metacarpals

Abstract

Standards for measuring the metacarpals are absent from commonly used osteometric guides. Perhaps the closest to a set of standard measurements in common use today are those proposed by Scheuer and Elkington (Scheuer and Elkington: J Forensic Sci 38 (1993) 769-788) for forensic sex assessment. They include caliper measurements of interarticular length, base and head width, base and head height, and maximum midshaft diameter. Over the last decade, a new set of measurements that encompass similar dimensions to those used by Scheuer and Elkington, but which are taken with a mini-osteometric board (MOB) have been developed by the lead author. Use of the MOB avoids the need to manipulate both the bone and calipers in three-dimensional space and causes less strain on the hands. However, the question of intra- and interobserver accuracy has not been adequately addressed for either set of measurements. The purpose of this study was to test both the Scheuer/Elkington and MOB measurements on 20 hands from 10 anatomical skeletons for intra- and inter-observer accuracy. The study found that 92% of the MOB measures had a lower intraobserver error, and 88% had a lower interobserver error than did the caliper measurements. It also found that the maximum midshaft diameter measurement used by Scheuer and Elkington is more repeatable than a mediolateral diameter. Overall, 88% of the 25 MOB measurements had median intraobserver error rates of under 1.5%, compared with 60% of the caliper measurements. Furthermore, the MOB measurements as a set were taken 10 to 12% faster than the caliper measurements.

Dimensional Accuracy of 3D-printed Models of the Right First Metacarpal Bones of Cadavers

“…The non-inferiority limit, which is 0.5, was the margin that was clinically acceptable to conclude that there is no statistically significant difference between the two groups. 5 The null hypothesis (Ho) in this study states that 3D-printed bones are inferior to cadaveric bones in terms of the difference in means. In contrast to this, the alternative hypothesis (Ha) claims that 3D-printed bones are noninferior to cadaveric bones in terms of the differences in means.…”

“…The independent variables included the type of 3D printer used and the dimensions which were based from the Scheuer and Elkington Measurements, were length, midshaft diameter, base width, base height, head width, and head height (Figure 1; Table 1). 5…”

“…For each replication, there was a different outcome assessor. However, contrary to the techniques of Scheuer and Elkington that used miniosteometric board (MOB), 5 this study used calipers since these were commercially available. The calipers used were all of the same brand, type, and size.…”

Inter-relationships of Metacarpals 1 to 5, Regarding Their Length, Metaphyseal Midshaft Width, Articular Surface Area of Head and Base, Age, and Sex: A Cadaveric Study

“…The results were within ranges in the previous literature, aside from the length of metacarpal 1 which was 43.8 mm with a standard deviation of 3.5 mm in a study from Singla and colleagues, which could be attributed to potential differences in sex and age groups, with no documentation of these factors in their study. 5,20 Wong and colleagues analyzed 50 total metacarpals (10 of each metacarpal) through computed tomographic analysis and observed the second metacarpal to be the largest of the metacarpals with a length of 62.7 mm, followed by metacarpal 3, 4, 5, and 1. 22 In comparison, our average lengths for each metacarpal were greater, which could also be accounted by the difference in age and sex of the subjects from whom metacarpals were collected.…”

“…The length and width of each articular surface of the head and base of the metacarpal were measured to obtain the area, as described in previous literature with addition of the articular surface. 20 Length was measured as the surface of the metacarpal from medial to lateral and the width from anterior to superior. The width was measured at midshaft.…”