A thumb carpometacarpal joint coordinate system based on articular surface geometry

• Published in: Journal of biomechanics 2013-03, Vol.46 (5), p.1031-1034
• Main Authors: Halilaj, Eni, Rainbow, Michael J, Got, Christopher J, Moore, Douglas C, Crisco, Joseph J
• Format: Article
• Language: English
• Subjects: 3-dimensional models; Adult; Anatomical coordinate system; Articular geometry; Biomechanical Phenomena; Carpometacarpal Joints - anatomy & histology; Carpometacarpal Joints - physiology; Computed tomography; Female; Geometry; Humans; Joints - anatomy & histology; Joints - physiology; Kinematics; Locomotion - physiology; Male; Middle Aged; Models, Biological; Physical Medicine and Rehabilitation; Range of Motion, Articular - physiology; Studies; Thumb - anatomy & histology; Thumb - physiology; Thumb CMC
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2012.12.002

Abstract The thumb carpometacarpal (CMC) joint is a saddle-shaped articulation whose in vivo kinematics can be explored more accurately with computed tomography (CT) imaging methods than with previously used skin-based marker systems. These CT-based methods permit a detailed analysis of the morphology of the joint, and thus the prominent saddle geometry can be used to define a coordinate system that is inherently aligned with the primary directions of motion at the joint. The purpose of this study was to develop a CMC joint coordinate systems that is based on the computed principal directions of curvature on the trapezium and the first metacarpal. We evaluated the new coordinate system using bone surface models segmented from the CT scans of 24 healthy subjects. An analysis of sensitivity to the manual selection of articular surfaces resulted in mean orientation differences of 0.7±0.7° and mean location differences of 0.2±0.1 mm. Inter-subject variability, which mostly emanates from anatomical differences, was evaluated with whole bone registration and resulted in mean orientation differences of 3.1±2.7° and mean location differences of 0.9±0.5 mm. The proposed joint coordinate system addresses concerns of repeatability associated with bony landmark identification and provides a robust platform for describing the complex kinematics of the CMC joint.