Reliability, validity, and responsiveness of the lower extremity measure for patients with a hip fracture

The purpose of this study was to determine whether currently published outcome measures of physical function would be suitable for use for older adults with a hip fracture. The measures that were considered were the Musculoskeletal Function Assessment (MFA) Instrument, the Older Americans' Resources and Services (OARS) Multidimensional Functional Assessment Questionnaire physical function subscale, the Toronto Extremity Salvage Score (TESS), and the Short Form-36 (SF-36). Following suggestions by an expert panel and patient interviews, the MFA was not tested further. The TESS was modified and renamed the Lower Extremity Measure (LEM).

Forty-three community-dwelling patients with a hip fracture completed the LEM, OARS, and SF-36 in the hospital so that the prefracture status could be obtained; they were then followed prospectively at six weeks and at six months. All patients were interviewed twice in the hospital to assess the reliability of the LEM (intraclass correlation coefficient = 0.85). To establish criterion validity, the measures were compared with the Timed Up and Go (TUG) test at six weeks. We tested a number of hypotheses to determine construct validity.

Only the LEM scores were significantly correlated with the TUG scores (r = -0.53, p = 0.03). The LEM scores were significantly correlated with the SF-36 subscale scores and the OARS scores. Patients with at least one comorbidity had a lower mean prefracture LEM score (90.0 +/- 9.7) than patients with no comorbidity (96.9 +/- 8.1) (p = 0.02). Patients who had used no walking aids before the fracture had a higher mean prefracture LEM score than those who had used a cane (95.5 +/- 5.8 compared with 85.5 +/- 12.7; p = 0.0007). Both the LEM and the SF-36 scores changed significantly between all of the time-periods (p < 0.05). Measures of responsiveness indicated that the LEM was the best measure for detecting changes in physical function.

The LEM can detect clinically important changes in physical function over time in patients with a hip fracture and would be most useful for clinical trials or cohort studies. Orthopaedists who are currently utilizing the SF-36 can be reassured that the physical function subscale is a valid measure for patients with a hip fracture.