Immediate Fit Using Innovative Technology Transtibial & Transfemoral Prosthesis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Immediate Fit Using Innovative Technology Transtibial & Transfemoral Prosthesis (NCT02886936), a non-randomized na study. The primary outcome is Prosthetic Comfort and Utility Questionnaire (Version 1).

2. Clinical Question

3. Trial Design

This completed study assessed the feasibility and design of the iFIT prosthetic system for transtibial and transfemoral amputees. The University of Pennsylvania is listed as sponsor. The registry lists enrollment of 71, a start date of 2018-05-01, and a primary completion date of 2022-05-31. Enrollment is not the same as the number who completed the primary questionnaire; that number is not reported in the registry record.

The design is listed as non-randomized, single-group, and unmasked. The registry describes two testing categories: Transtibial Testing and Transfemoral Testing, with a further category called Transtibial Testing 2(Follow Up). These labels do not establish a randomized comparison. The study description says that participants would wear the device for 2 weeks and compare it with their own prosthetic if they currently had one. Whether each participant had an existing prosthetic, and how many made such a comparison, are not reported in the registry record.

The study aimed to assess device design, user satisfaction, and feasibility, and to gather information that could inform future design iterations. The planned assessments included questionnaire responses, device breakages or adverse events, and gait and socket measures. The registry lists 11 outcome measures, including walking speed, internal socket pressure, double support, limp index, stride length, stance phase, and residual limb circumference relative to internal socket diameter. The registry does not report results for these measures in the record summarized by the listed outcomes.

The primary endpoint was the Prosthetic Comfort and Utility Questionnaire, version 1, at 2 weeks. The primary analysis population is described as persons completing the 2 week trial from the first cohort, but the number in that population and its results are not reported. The registry record lists no analyses. A sample-size justification, detailed statistical analysis plan, and interim analyses are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Persons completing the two week trial from the first cohort.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Transtibial and Transfemoral subjects that enrolled in the study.

6. Primary Endpoint

The registry lists the primary outcome as Prosthetic Comfort and Utility Questionnaire (Version 1), measured over 2 weeks.

The primary endpoint was the score on the Prosthetic Comfort and Utility Questionnaire, version 1, at 2 weeks. The questionnaire was based on the Prosthetic Evaluation Questionnaire and used questions focused on comfort, satisfaction, and the utility of a prosthetic socket. Each question used values from 1 (Poor) through 5 (Excellent). The version used in this study had 7 questions, with a total possible score of 35 and a lowest score of 7; higher totals indicate better ratings.

This type of patient-reported measure captures the participant’s own assessment of comfort and utility rather than a measurement made solely by an instrument or an observer. In general, patient-reported outcomes can describe aspects of device experience that may not be represented by walking or socket measurements alone. The registry specifies the total score and standard deviation as the intended summary, and identifies the primary population as persons completing the 2 week trial from the first cohort.

The registry record does not report the observed total score mean, standard deviation, or number of participants contributing to this endpoint. It therefore does not permit a quantitative description of the typical questionnaire rating or its variability. It also does not report a comparison estimate between the iFIT device and participants’ own prosthetics.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous questionnaire total summarized as a mean and standard deviation. In general, a mean describes the average score in the participants whose data are included, while a standard deviation describes how spread out individual scores are around that average. These quantities answer different questions: a mean describes the group’s central score, while a standard deviation describes variation among participants. Neither is reported for the primary endpoint in the registry record.

A mean alone does not show how precisely the study has estimated the underlying average. In general, a confidence interval expresses a range of values compatible with the data and a stated method, and its width reflects both variability and the amount of information available. No confidence interval for the primary score is reported in the registry record. The participant count contributing to the primary endpoint is also not reported, so the precision of a mean cannot be evaluated from the record.

The score’s scale has defined bounds: each of 7 questions uses values from 1 through 5, the total ranges from a minimum of 7 to a maximum of 35, and higher totals are better. These bounds help interpret a reported score, but the registry record does not give an observed mean or distribution. The scale description alone cannot show where participants’ scores fell, whether responses clustered near one end, or how much participants differed.

The study design matters when interpreting any comparison. In general, random allocation can help balance both measured and unmeasured participant characteristics across groups. This study is listed as non-randomized and single-group, with no masking. Its testing categories should not be treated as randomized arms or as interchangeable control groups. The registry description mentions comparison with a participant’s own prosthetic if they currently had one, but does not report how many participants had one or how any such comparison was analyzed. A numerical difference, adjusted comparison, or uncertainty estimate for that comparison is not reported.

The registry record lists 11 outcome measures. When multiple outcomes are examined, general statistical practice recognizes that the chance of finding at least one apparently notable result can increase if many tests are conducted. Methods for addressing multiplicity may include prioritizing a primary outcome or adjusting interpretation across tests. The registry record does not report a multiplicity strategy, and it lists 0 analyses. No test statistics or p-values are reported for the listed outcomes.

The record’s planning illustration is described as using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect set as a stated fraction of an observed effect. In general, a sample-size calculation estimates how many observations would be needed under chosen assumptions; it does not describe the number actually analyzed. The stated illustration uses a two-arm framework, whereas the study is listed as non-randomized and single-group. It should therefore be understood only as a planning illustration, not as evidence of the study’s design or its observed ability to detect an effect. The calculated planning counts are not reported in the registry record summarized by these registry entries. Any such counts are planning illustrations, not observed power.

In general, over-dispersion means that observed variability is greater than a statistical model expects. It can make model-based uncertainty estimates too small if the model does not allow for that extra variability. The registry record does not report a model for the primary endpoint or indicate that over-dispersion was assessed. Because the outcome is a bounded questionnaire total and the registry specifies a mean and standard deviation, no additional modeling approach can be attributed to the study from this record.

The record does not describe how missing questionnaire responses were handled, whether partial questionnaires could contribute to a total, or how the analysis population was defined beyond persons completing the 2 week trial from the first cohort. General methods for incomplete data depend on why observations are missing and on assumptions about the unobserved values. No imputation, sensitivity analysis, or other missing-data procedure is reported in the registry record.

These distinctions separate the design, the intended summaries, and the results that are actually reported. A defined endpoint and analysis framework do not substitute for the observed estimate, its variability, and the number of participants contributing data. Those primary-result details are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 11 outcome measures. These include the primary questionnaire and secondary measures of adverse events, walking speed, internal socket pressure, double support, limp index, stride length, stance phase, and residual limb circumference relative to internal socket diameter. Having multiple outcomes can provide a broad description of feasibility and device performance, but it also creates the general statistical issue of multiplicity: when many questions are tested, the chance of at least one apparently notable finding may increase. The registry record does not report a strategy for controlling or interpreting multiplicity.

The number of analyses is listed as 0. No statistical tests, effect estimates, confidence intervals, or p-values are reported in the record. A listed outcome is not itself a reported analysis, and the absence of analysis entries does not establish that no analyses were conducted outside the registry.

The primary population is described as persons completing the 2 week trial from the first cohort. The number of such participants is not reported in the registry record. The record does not state how many people began each assessment, whether all questionnaire items were completed, or whether any participants were excluded from endpoint summaries.

Handling of missing outcome data, analysis populations beyond the primary population description, and sensitivity analyses are not reported in the registry record. In general, these details matter because estimates can depend on which participants contribute data and how incomplete observations are treated. The registry also does not report a statistical analysis plan or interim analyses.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The safety entries give counts of participants at risk and participants affected in each testing category. For serious adverse events, the record lists 0 affected participants in Transtibial Testing, 0 in Transtibial Testing 2(Follow Up), and 0 in Transfemoral Testing. Deaths are also listed as 0 in each category.

For other adverse events, the record lists 2 affected participants among 26 at risk in Transtibial Testing, 0 among 27 at risk in Transtibial Testing 2(Follow Up), and 0 among 18 at risk in Transfemoral Testing. These are counts recorded for the respective categories; they are not a randomized comparison. The registry does not provide event descriptions in the serious-event terms list, which is empty, and does not report details about the other events’ nature, timing, duration, or severity.

Zero recorded serious events does not establish that the possibility of such events is absent. In general, event counts describe what was recorded among the participants at risk, while the ability to characterize uncommon events depends on the amount and detail of observed follow-up. The registry record does not report a comparative safety analysis or enough detail to infer how the categories differed in follow-up or participant characteristics.

12. What the Result Does, and Does Not, Mean

The registry record describes a study intended to assess the feasibility, design, and user experience of an immediate-fit prosthetic system. It specifies a 2 week wear period and a primary questionnaire focused on comfort, satisfaction, and socket utility. It also lists gait, socket, limb-measurement, and adverse-event outcomes. These details clarify what the study set out to assess.

However, the primary questionnaire’s observed mean and standard deviation are not reported in the registry record. The number of participants contributing to that endpoint is also not reported. Without those results, the primary ratings and their variability cannot be described quantitatively. No confidence interval or statistical test for the primary outcome is reported either. The registry’s enrollment of 71 does not establish that all enrolled participants completed the trial or contributed to the primary endpoint.

The study’s non-randomized, single-group, unmasked design also limits what can be inferred about comparisons. The description says participants could compare the iFIT device with their own prosthetic if they currently had one, but the record does not report the number making such a comparison or the results. Testing categories are not randomized control groups, so their counts should not be interpreted as evidence of comparative effects.

The safety counts record no serious adverse events or deaths in the listed categories, and 2 participants with other adverse events in Transtibial Testing. Those counts describe the registry entries; they do not establish a comparative safety profile or resolve uncertainty about events that were not recorded. Event details are not reported.

In general, a feasibility study can inform whether a device and its assessments warrant further evaluation, but it does not by itself establish a causal effect. For this record, the principal questionnaire results and many outcome results are not reported, so the available information does not support conclusions about the magnitude or precision of participant ratings or about comparative performance.

13. Why This Trial Matters Statistically

This trial is statistically notable because its purpose and design call for interpretation as a feasibility assessment, not as a randomized comparison. The registry lists non-randomized allocation, no masking, and a single-group model. The testing categories describe different forms of prosthetic assessment, including a follow-up category, but do not constitute randomized arms. Recognizing that distinction prevents descriptive counts from being mistaken for comparative evidence.

The primary outcome is a participant-reported measure with a defined score range and direction. This makes the intended construct clear: higher questionnaire totals represent better evaluations of comfort, satisfaction, and socket utility. Yet an endpoint definition is only one part of statistical interpretation. Without the observed mean, standard deviation, and number of participants contributing data, the reader cannot judge the result’s magnitude, variability, or precision.

The record also illustrates why enrollment and analyzed population size should not be treated as interchangeable. Enrollment is listed as 71, while the primary population is described as people who completed the 2 week trial from the first cohort. The number completing that trial is not reported in the registry record. Those quantities answer different questions, and the distinction matters for interpreting the amount of information behind an estimate.

The breadth of listed outcomes reflects the study’s interest in both user experience and physical or gait-related measurements. In general, evaluating several outcomes requires clarity about which are primary, how analyses are planned, and how results should be interpreted together. The registry identifies a primary questionnaire but does not report a multiplicity strategy or analyses.

Finally, the safety counts are useful as descriptive registry information, while their limited detail and lack of a controlled comparison constrain interpretation. The record’s value is in defining the study question, endpoint, outcome scope, and observed safety entries; the missing outcome estimates mean its quantitative findings cannot be fully assessed.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary endpoint is described, but its observed mean, standard deviation, and contributing participant count are not reported in the registry record. As a result, the primary questionnaire outcome cannot be evaluated for magnitude or precision. The registry also lists no analyses, and does not report results for the listed gait, socket, and limb-measurement outcomes.

The primary population is limited by definition to persons completing the 2 week trial from the first cohort, but the number completing the trial is not reported. The record does not describe recruitment or completion by testing category, reasons for non-completion, or whether participants with incomplete questionnaire responses were included. Enrollment of 71 should therefore not be read as the endpoint sample size.

The non-randomized, unmasked, single-group design does not support treating the testing categories as randomized comparators. Although participants could compare the device with their own prosthetic if they had one, the registry does not report how many did so, how that comparison was conducted, or its numerical results. The record also does not describe adjustment for differences between participants or devices.

Other limitations specific to the record include the absence of a reported statistical analysis plan, sample-size justification, interim analyses, missing-data methods, and multiplicity strategy. The registry describes a sample-size planning framework, but the calculated planning counts are not reported in the registry record summarized by these registry entries. Details of the adverse events beyond the participant counts are also not reported. These gaps limit assessment of the study’s precision, outcome completeness, and safety findings.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Immediate Fit Using Innovative Technology Transtibial & Transfemoral Prosthesis — NCT02886936.
• Registry record last updated 2023-06-26; status last verified 2023-05.
• Results first posted 2023-06-26.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry identifies a completed study of the iFIT transtibial and transfemoral prosthetic systems, sponsored by the University of Pennsylvania. It lists enrollment of 71, a start date of 2018-05-01, and a primary completion date of 2022-05-31. The design is non-randomized, unmasked, and single-group.

The primary outcome is the Prosthetic Comfort and Utility Questionnaire, version 1, collected at 2 weeks. It has 7 questions, scores from 7 to 35, and higher scores indicate better ratings. The primary population is persons completing the 2 week trial from the first cohort. The observed questionnaire mean, standard deviation, and contributing participant count are not reported in the registry record.

The record lists 11 outcome measures and 0 analyses. It records no serious adverse events or deaths in the reported testing categories, and 2 participants with other adverse events in Transtibial Testing. The remaining numerical outcome results and details of those other events are not reported in the registry record.