Functional Instability of the Second to Fifth Metacarpophalangeal Joints

Background. Clinically, functional instability (FI) of metacarpophalangeal joints (MCPJ) is not considered to represent a pathology. This excessive mobility can be detected by the application of external forces to a MCPJ at different angles. Our study aimed to measure the FI of 2nd to 5th MCPJ. Materials and methods. A group of 36 healthy right-handed individuals were enrolled. The value of FI was measured in millimeters and verified by a CT scan. Statistical calculations was made in Statistica v.10.0. Results. The largest values of the right and left-hand finger posterior displacement (FI) in the second to fifth MCPJ were obtained in the neutral position 0° (p<0.05). Measurements of volar displacement of the proximal phalanx second to fifth MCPJs in both hands revealed higher values at position 0° (p<0.05). Conclusions. 1. FI of the second to fifth MCPJs is determined by anatomical configuration and dynamic stabilizers. 2. Instability measurements show that posterior displacement of the proximal phalanges is greater by at least 1 mm in the 0° neutral position.