GRIP STRENGTH CHARACTERISTICS USING FORCE TIME CURVES IN RHEUMATOID HANDS

Abstract

To assess the effect of deformity on Grip strength characteristics in the Rheumatoid Hands using force time curves. Forty seven (6 males and 41 females) patients with mean age 62 years (29–79 yrs) with Rheumatoid arthritis had their handgrip strength measured with closed fluid dynamometer generating force-time curves.

These were analysed further in blinded fashion for:

1. peak force;

2. average force;

3. time to peak

4. and variance of the force data through the plateau region (final 60% of curve).

Data was also collected on joint mobility, pain and disability using Patient Evaluation Measure (PEM) and Functional Disability Scores (FDS).

The patients were divided into five groups according to the degree of deformity: No deformity, ulnar deviation, Boutonniere, Swan neck or combined deformities (two or more deformities). These patient groups showed significant differences in grip strength (p value < 0.01). Patients with combination of deformities showed low peak and average forces as measured on force-time curves. The hands with Swan neck deformities had the highest variability in the plateau region of the curve and had the greatest disability scores both with PEM and FDS scores (P Value < 0.005). This group was particularly disabled (P Value < 0.007) being less able to sustain the grip over time.

Swan Neck Deformity causes the most significant dysfunction and this should be carefully considered when making decisions regarding surgery.