Sources of goniometric error at the elbow

Area of Science:

• Biomechanics
• Physical Therapy
• Medical Measurement

Background:

• Goniometry is a common method for measuring joint angles.
• Accuracy in goniometry is crucial for effective physical therapy assessment.
• Potential sources of error in goniometry require investigation.

Purpose of the Study:

• To assess the accuracy of goniometry in measuring elbow joint angles.
• To identify potential sources of error in goniometric measurements.
• To compare goniometric accuracy with a photographic reference standard.

Main Methods:

• Forty-six physical therapy students performed elbow goniometry using plastic or steel goniometers.
• Three measurement protocols were used: ALIGN, ASSIGN, and PROM (passive range of motion).
• Measurements were compared against a photographic reference standard for accuracy.

Main Results:

• Goniometric accuracy (s +/- 2.4-3.4 degrees) was lower than photographic accuracy (s +/- 0.7-1.1 degrees).
• Goniometer alignment, landmark identification, and manual force during PROM contributed to measurement error.
• Most goniometric measurements showed statistically significant differences from photographic measurements (p < .05).

Conclusions:

• Small systematic errors in alignment and landmark identification may explain discrepancies.
• Standardized methods enable even inexperienced raters to use goniometers accurately for elbow position measurement.