Erratum: The biomechanics of knuckle-walking: 3-D kinematics of the chimpanzee and macaque wrist, hand and fingers (Journal of Experimental Biology (2020) 223 (jeb224360) DOI: 10.1242/jeb.224360)

Abstract

The description of the calculation of metacarpophalangeal (MCP) joint abduction and adduction was incorrect. It was originally described as the angle between the metacarpal and the projection of the phalangeal vector onto the plane of best fit of the metacarpals. This was not the case. The MCP adduction/abduction angle was calculated as the 3-D angle between the phalangeal vector projected onto the sagittal metacarpal plane (gray plane of Fig. 2) and the vector describing the actual position of the phalanges. The originally described calculation is sensitive to changes in MCP flexion and extension, whereas the calculation actually used is not. No data, analyses or conclusions are changed as a result of this; only the description of the calculation used in the Materials and Methods and the representation of this in Fig. 2 were incorrect. The corrected text in Materials and Methods (third to last sentence in ‘Metacarpophalangeal motion’) reads: ‘Adduction and abduction were calculated as the 3-D angle between the vector projection of the phalangeal markers onto the sagittal metacarpal plane (vpp_proj in Fig. 2C,D) and the actual vector defining each phalanx. This calculation returns a value for abduction and adduction that is insensitive to the degree of MCP flexion and extension.’ The original and corrected versions of Fig. 2 are shown below. Both the online full-text and PDF versions of the article have been updated. The authors apologise to the readers for any inconvenience caused and thank Dr Joris Leijnse for identification of this error.