The effect of index finger distal interphalangeal joint arthrodesis on muscle forces and adjacent joint contact pressures

Abstract

Distal interphalangeal joint arthrodesis is a frequent surgical operation performed to treat severe arthritis. Nevertheless, the angle selected when fusing the joint is arbitrarily chosen without any quantified data concerning its mechanical effects, thus preventing the optimal choice for the patient. In the current study, we realized an experiment and developed a numerical model to investigate the effect of fusion angle on the biomechanics of adjacent non-operated joints. Six participants performed a pinch grip task while arthrodesis was simulated with a metal splint. Kinematic and force data were recorded during this task and used in a biomechanical model to estimate contact pressures in adjacent joints. The biomechanical model involved combining a multibody system and a finite element method. Results showed that the angle of any distal interphalangeal joint arthrodesis influences index finger kinematics and maximal grip force in several participants. For one participant, in the arthrodesis simulation, we observed an increase of 1.9 MPa in the proximal interphalangeal joint contact pressure. Our results provide quantified information about the biomechanical consequences of this surgical operation and its potential long-term effects.

Lightness of touch

“…These 'Popeye' muscles are crucial to the survival of wall and cliff climbers. The pinch force, generated by these long flexors as they flex the distal interphalangeal joints is between 25 N and 50 N. 5 (If the surface area of the end of a pair of forceps is assumed to be 5 mm2 (5 x 10 -6 m 2 ), the pressure exerted on tissue by pinching the forceps is more than 5 million Nm2 (Pressure = Force (N) / Area (m 2 ) or the equivalent of 725 psi. Tissue damage is inevitable (Figure 2B).…”