Smartphone goniometer for reliable and convenient measurement of finger range of motion: a comparative study

Abstract

Objective Goniometer measurements are commonly used in hand clinics to follow progress or as an outcome measure for acute and chronic conditions. The use of an Apple iPhone goniometer application (smartphone app) may provide a practical alternative for clinicians. This study sought to assess accuracy in range-of-motion measurements obtained by a smartphone app compared to a traditional universal goniometer (UG) in healthy and diseased hands. Methods Patients with various hand disease processes were recruited through a tertiary hospital hand clinic, as well as healthy volunteers. Middle and little fingers were assessed at the metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints for flexion and extension. Measurements were taken using a universal goniometer and a smartphone app by two independent evaluators using a standardised proforma. Results Twenty patients were recruited (50% male; 13 healthy volunteers and seven with hand pathology). There were no significant differences in measurements using the smartphone goniometer. The only significant difference found using the universal goniometer was for little finger PIP joint flexion; however, the difference was only 2.5°. Comparison of the average measurements using a UG and smartphone app found significant differences for six joints, with none of these > 5° (largest 4.6°). Conclusion The smartphone app is as reliable as traditional goniometry techniques and would be a practical tool for everyday use in hand clinics. Its uptake may provide broader utility for patient self-measurement and telemedicine.