What a Difference 37 Minutes Make—Investigating Prosthesis Users’ Accommodation to Changes in Prosthetic Componentry

Background: Becoming accustomed to a new prosthesis or orthosis is potentially a lengthy process that may be influenced by a variety of patient- and device-specific factors. This makes it difficult in clinical practice and research to purposefully allocate accommodation times that are neither too short nor too long. The goal of this work was to determine the average duration, in time and step count, until a lower-limb prosthesis user is acclimated to a new prosthetic foot. Methods: Participants’ prostheses were modified by replacing the original foot with a different type. Step counts, measures of gait symmetry, and self-reported ratings of accommodation were recorded in prescribed increments over a total period of 30 days. The resulting time series were approximated as a power function and analyzed to extract the average period after which the accommodation level had reached 90% of the eventual value. Results: A total of 18 participants were enrolled, of whom 14 generated enough data to be included in the analysis. On average, they reached 90% of accommodation after using the new foot for 37 minutes and walking 365 steps. Discussion: Recommendations for accommodation periods, based on this methodology, are shorter than frequently assumed. These differences are likely attributable to divergent definitions of the construct of “full accommodation.” Our findings may be adopted to inform the design of efficient protocols in prosthetics and orthotics research and to enhance the clinical practice of prescribing and fitting prostheses or orthoses for individual patients. Clinical Relevance: Allowing too much or not enough accommodation time after changes to a prosthesis is problematic, as it can lead to flawed clinical decisions, undue burdens for the patient, or both. Determining a reasonable accommodation period and applying it consistently can help mitigate these issues.