The intra-rater reliability of a revised 3-point grading system for accessory joint mobilizations

Joint mobilizations are often quantified using a 4-point grading system based on the physiotherapist’s detection of resistance. It is suggested that the initial resistance to joint mobilizations is imperceptible to physiotherapists, but that at some point through range becomes perceptible, a point termed R1. Grades of mobilization traditionally hinge around this concept and are performed either before or after R1. Physiotherapists, however, show poor reliability in applying grades of mobilization. The definition of R1 is ambiguous and dependent on the skills of the individual physiotherapist. The aim of this study is to test a revised grading system where R1 is considered at the beginning of range, and the entire range, as perceived by the physiotherapists maximum force application, is divided into three, creating 3 grades of mobilization.

Thirty-two post-registration physiotherapists and nineteen pre-registration students assessed end of range (point R2) and then applied 3 grades of AP mobilizations, over the talus, in an asymptomatic models ankle. Vertical forces were recorded through a force platform. Intra-class Correlation Coefficients, Standard Error of Measurement, and Minimal Detectable Change were calculated to explore intra-rater reliability on intra-day and inter-day testing. T-tests determined group differences.

Intra-rater reliability was excellent for intra-day testing (ICC 0.96–0.97), and inter-day testing (ICC 0.85–0.93). No statistical difference was found between pre- and post-registration groups. Standardizing the definition of grades of mobilization, by moving R1 to the beginning of range and separating grades into thirds, results in excellent intra-rater reliability on intra-day and inter-day tests.