Orthopaedic applications of a validated force-based biomechanical model of the index finger.

An anatomically realistic biomechanical model of the index finger was created using a force-based approach in order to predict the isometric fingertip force or dynamic movement based on the forces of 7 index finger musculotendons. The model was validated for static forces through comparison with experimental results from 5 cadaver specimens. The model reliably simulated the isometric fingertip force produced by loading individual tendons. The average error in fingertip force direction was less than 2° and the average error in magnitude was less than 10% across finger postures for each muscle. Subsequent employment of the model to examine force transmission from the long flexors revealed a strong dependence of joint contact force on finger posture for a given tendon load. This may have ramifications for osteoarthritis as high joint contact forces are thought to contribute to the disease.