Validity and Interobserver Reliability of Visual Observation to Assess Partial Weight-Bearing

Abstract 

Hurkmans HL, Bussmann JB, Benda E. Validity and interobserver reliability of visual observation to assess partial weight-bearing.

Objective

To determine the validity and interobserver reliability of visual observation to assess partial weight-bearing.

Design

Validation and interobserver reliability study.

Setting

University medical center.

Participants

Patients (N=10) with a total hip arthroplasty operated 1 to 12 months prior to the study referred by 10 physical therapists (5 experienced and 5 inexperienced in training patients in partial weight-bearing).

Interventions

Not applicable.

Main Outcome Measures

The amount of weight-bearing assessed by visual estimation (visual analog scale score) in percentage body weight (BW). Actual weight-bearing (percentage BW) as measured with the Pedar Mobile system. The mean difference (systematic error) between visual estimation and the Pedar system and the SD of the differences (random error) were determined by the limits of agreement (LOA) method with multiple observations per subject. The intraclass correlation coefficient (ICC) was calculated as a measure for the interobserver reliability.

Results

The mean difference ± SD between visual observation and the reference method was –9.5±20.1 percentage BW (95% confidence interval, –24.0 to 5.0 percentage BW) with LOA ranging from –49.8 to 30.8 percentage BW. The ICC was .57. The therapists' experience in partial weight-bearing training had no effect on the mean difference (P=.349) between the 2 methods.

Conclusions

Visual observation is not a valid and reliable method to assess partial weight-bearing.

Key Words: Rehabilitation, Reproducibility of results, Weight-bearing

List of Abbreviations: BW, body weight, CI, confidence interval, ICC, intraclass correlation coefficient, LOA, limits of agreement, PWB, partial weight-bearing, THA, total hip arthroplasty, VAS, visual analog scale