Measurements of Best, Worst, and Average Socket Comfort Are More Reliable Than Current Socket Comfort in Established Lower Limb Prosthesis Users.

Objective: To evaluate test-retest reliability and related measurement properties of items developed to assess best, worst, and average prosthetic socket comfort.

Design: Methodological research to assess test-retest reliability of 4 individual socket comfort survey items. Socket comfort items were included in a self-report paper survey, which was administered to participants 2 to 3 days apart.

Setting: General community.

Participants: A minimum convenience sample of participants (N=63) was targeted for this study; 72 lower limb prosthesis users (>1y postamputation) completed the survey and were included in the final dataset.

Interventions: Not applicable.

Main Outcome Measure: The expanded socket comfort score (ESCS) was adapted from the original socket comfort score (SCS). The original SCS is a single-item self-report instrument developed to assess a lower limb prosthesis user's current socket comfort. Three additional items were designed to assess the user's best, worst, and average socket comfort over the previous 7 days.

Results: Best, worst, and average socket comfort items demonstrated better reliability, as indicated by higher intraclass correlation coefficients. As such, these items also exhibited lower measurement error and smaller minimal detectable change values than the item that measured current socket comfort. However, test-retest coefficients for all 4 ESCS items were below the level desired for evaluation of within-individual changes of socket comfort.

Conclusions: Items that assess best, worst, and average comfort provide a more stable measurement of socket fit than the existing SCS instrument. Although administration of all 4 ESCS items may provide more comprehensive assessment of a lower limb prosthesis user's socket fit, administrators should expect variations in scores over time owing to the variable nature of the underlying construct over time. Future research should examine whether the ESCS provides an improved overall assessment of socket fit.