Does the Prosthetist’s Generation Affect Transfemoral Interface Choice?

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By Gerald Stark, PhD, MSEM, CPO/L, FAAOP(D)

The goal of a recent survey I conducted regarding transfemoral interface designs was to understand the trends related to practitioner experience and trans­femoral interfaces. There were 233 respondents with a 100 percent completion rate and 46 additional qualitative comments. The largest group (29 percent) had 26 years or more of experience, followed by those with 0-5 years of experience at 18 percent. When rating their expertise, the largest group was "expert" at 41 percent, followed by "intermediate" at 33 percent and "specialist" at 13 percent. The distribution of confidence and expertise indicated a higher degree of confidence and self-efficacy with transfemoral interfaces and fitting. 

Most of the respondents, 77 percent, indicated that they performed 0-5 transfemoral fittings or scans per month followed by 18 percent of the sample seeing 6-10 patients with transfemoral amputations. The work environment of the sample group was bimodal, with 36 percent employed in companies with multiple offices and private ownership and 34 percent in single office facilities with private ownership. Practitioners working in corporate ownership were underrepresented at 8.62 percent (approximately 20 percent of all O&P clinics are corporate owned).

When asked what innovations will have the biggest impact on transfemoral fitting, osseointegration was highest, followed by elevated vacuum, and adjustable socket systems.

The distribution of liner versus non-liner direct fitting in transfemoral fittings was a bit surprising at 79 percent choosing a liner. Although previous distributions of liner to non-liner use in transfemoral prostheses is not readily available, anecdotally, the distribution may have been closer to 50-50 ten years ago. This may be changing due to the increased number of patients each practi­tioner is being asked to see, or greater complexity in achieving custom interface comfort and suspension. When asked what percentage of patients would be good candidates for osseointegration, the aggregate group indicated 16 percent of patients. This value is also difficult to compare since no previous estimation exists in the literature.

With respect to the number of liners used, 40 percent of respondents said one to two liners were provided each year for transfemoral interfaces, 33 percent said two to three liners, and 26 percent said three to four liners per year, which would reveal the annual costs of liner use and perhaps the expectation that osseointegration may, in part, provide a solution.

A small negatively significant relationship between years of experience and liner versus non-liner use, osseointegration techniques, and number of liners used per year indicated that clinicians with more experience may utilize non-liner interfaces slightly more often and provide slightly fewer liners per year.

Experience, proficiency, number of patients seen, or work context could not be used to predict liner check sockets needed, or attitudes regarding osseointegration.

New questions generated from the survey could be: How has the increasing patient volume changed what types of components and fitting processes are utilized? How has the increased use of liner suspension techniques affected the prevalence of custom proximal brim-forming techniques, interface biomechanics, and alignment? How do the different clinical groups work together to implement innovations in clinical practice? And ultimately, how do these reflexive practitioner values regarding componentry positively or negatively affect patient function and comfort?

Gerald Stark, PhD, MSEM, CPO/L, FAAOP(D), is a senior clinical specialist for Ottobock based in Austin, Texas. He can be reached at gerald.e.stark@gmail.com.