Validity of Visual Assessment of Sit to Stand After Hip Fracture.

Background And Purpose: When treating older adults post-hip fracture, physical therapists routinely assess the sit-to-stand (STS) task using observational analysis. Studies have demonstrated that significant movement asymmetries in ground reaction force production of the fractured lower limb persist during STS, even though individuals may rise independently. To date, the validity of therapist judgments of lower limb force during STS has not been addressed. The purpose of this observational cohort study was to determine the accuracy of physical therapists' observational assessments of STS for detecting the involved limb and its ground reaction force contribution in older adults post-hip fracture.

Methods: Eighteen home health physical therapists assessed 10 videotapes of older adults post-hip fracture rising from sitting and judged the side of involvement and the amount of ground reaction force generated by the fractured lower limb. Each videotape was synchronized with its respective force data. A wide spectrum of asymmetry in rising was represented in the test videos. Before making these judgments, the therapists viewed a separate set of training videos and received instructions in the use of specific visual cues to assist with subsequent judgments.

Results And Discussion: Therapists judged the involved side correctly 74% of the time. Mean accuracy in judging ground reaction force output was 39% across all therapists. Force symmetry did not significantly influence accuracy of force judgments. Inaccurate judgments of force may limit therapeutic intensity and minimize the potential for developing motor strategies that favor force production of the involved limb. Augmenting observational analysis of STS with quantitative data could assist in optimizing restorative function.

Conclusion: Judgments of lower limb ground reaction force output during STS based on observation alone are not valid and may need to be supplemented with quantitative data.