Carrying angle; Second and fourth digit ratio (2D:4D): A correlation study of University of Port Harcourt Students

The carrying angle is the angle (in the sagittal plane) formed by the axes of the arm and the forearm, with the elbow in full extension. Females have wider carrying angle due to a wider hip design for obstetric reasons. This study was carried out to determine the relationship between carrying angle and 2D-, 4D-length and ratio. One hundred and nine (109) subjects comprising 49 males and 60 females were randomly selected from the University of Port Harcourt. Carrying angle was measured using a goniometer (after the midpoint of the arm and forearm were determined using a flexicurve), while 2D-, 4D-length was measured using a digital vernier caliper. Data was analyzed using statistical package for the social science (SPSS version 22.0). The results showed that for males on the right, carrying angle (CA) significantly correlated with 2D length (r = 0.461, R2 = 0.21, p < 0.01) and 4D length (r = 0.474, R2 = 0.22, p < 0.01). While on the left, it correlated with 2D length (r = 0.450, R2 = 0.20, p < 0.01) and 4D length (r = 0.366, R2 = 0.13, p = 0.05). For females on the right, it significantly correlated, with 2D length (r = 0.469, R2 = 0.22, p < 0.01) and 4D (r = 0.357, R2 = 0.13, p = 0.003), 2D:4D ratio (r = 0.285, R2 = 0.08, p = 0.014). While on the left, it correlated with 2D (r = 0.449, R2 = 0.20, p < 0.01) and 4D (r = 0.322, R2 = 0.10, p = 0.006). Females had higher CAs, while males had longer 2D and 4D. Significant differences were observed in all measured parameters between sex at p < 0.05, except for the right 2D, 2D:4D; and the left 2D:4D. The right 4D and 2D better were better predictors of CA in males and females respectively. The findings from this study will be useful for estimating CA from 2D, 4D and 2D:4D and also in surgical repair (management) of elbow fracture or dislocation.

Key Words: 2nd digit, 4th digit, length, ratio.