Accuracy and inter-observer reliability of visual estimation compared to clinical goniometry of the elbow.

Objective: To test the hypothesis that visual estimation by a trained observer is as accurate and reliable as clinical goniometry for measuring elbow range of motion.

Methods: Instrument validity and inter-observer reliability of visual estimation was evaluated on a consecutive series of 50 elbow contractures. Four observers with different levels of elbow experience first estimated extension and flexion of the contracted elbows and then measured them with a blinded goniometer.

Results: Instrument validity for visually-based goniometry was extremely high. ICC scores were 0.97 for both extension and flexion estimations. Systematic error was negligible (1°) with upper limits of agreement being 9° (95% CI: 7°-11°) and 8° (95% CI: 6°-10°), respectively, for extension and flexion. For the expert surgeon, 92% of the visual estimates were within 5° of the value obtained by clinical goniometry. Between experienced observers (elbow surgeon and physician assistant), the ICC's were very high-0.96 for extension and 0.93 for flexion. The systematic errors were low, from -1° to 1° with upper limit of agreement being 11° (95% CI: 8°-14°). However, agreement was poor between an inexperienced study coordinator and the others (ICC's: 0.51-0.38, systematic errors: 8°-18°, upper limit of agreement: 32°-40°). The accuracy of the visual estimations made by the experienced elbow surgeon was as good as the measurements taken with a goniometer by the physician assistant or the clinical fellow and better than those taken by an inexperienced study coordinator.

Conclusions: The trained human eye is highly capable of accurately estimating the range of motion of the elbow, compared to conventional clinical goniometry, depending on the experience of the observer. Methods: Diagnostic study, Level II.