This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for A Comparative Analysis Between College Park Sidekick Feet and Conventional Stubby Prosthesis (NCT02921295), a randomized na study. The primary outcome is Average Speed for 10 Meter Walk Test.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02921295 |
| Phase | NA |
| Condition | Amputation Stumps |
| Allocation | Randomized |
| Design model | Sequential |
| Masking | None (open label) |
| Enrollment | 1 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Angela DeCandia |
| Results posted | Yes |
2. Clinical Question
Population
The stated research aim concerns people with bilateral above-knee amputations. The registry lists Amputation Stumps as the condition and records an enrollment of 1. Further participant characteristics are not reported in the registry record.
Intervention
The intervention was articulated stubby prostheses called Sidekicks, manufactured by College Park. The registry describes their use during a sequential crossover design.
Comparator
Conventional stubby prostheses were used for baseline measures and served as the comparator to the Sidekicks. The registry labels the arms Stubbies and Sidekicks.
Primary question
The primary endpoint was average speed on the 10 Meter Walk Test, reported in m/s. The broader stated aim was to compare gait velocity, exertion, and balance. The investigators also stated expectations about balance on level and gravel surfaces, walk-test time, and perceived exertion; the posted primary endpoint specifically measures average walking speed.
The registry describes a comparison of prosthetic feet under a 2 hour protocol, with measurements described as occurring 2 times throughout study completion, every 1 hour. The walk was unassisted over a 10-m distance with a running start. The primary question is whether the recorded average speeds differ between the conventional stubby prostheses and Sidekicks. The posted arm summaries are 0.57 m/s for Stubbies and 0.53 m/s for Sidekicks, each with n=1. Those isolated values do not establish a reliable group-level contrast or answer the broader questions about exertion and balance. Two secondary outcomes are listed: Timed up and go Test Time and Gait Symmetry Index.
3. Trial Design
The registry identifies NCT02921295 as a completed randomized study with no masking. Its design model is listed as sequential, and the arm description calls it a sequential crossover design. Conventional stubby prostheses were used for baseline measures; articulated Sidekick stubby prostheses were used as the intervention. The registry records enrollment of 1. Although two arm summaries are posted, each has n=1, and the record does not report participant-level details that would clarify the sequence of measurements beyond the design description.
The primary outcome was Average Speed for 10 Meter Walk Test, measured in m/s. The description says the participant covered a 10-m distance unassisted, using a running start, and that each pass was timed. Average speed was calculated for each pass as 10m divided by recorded time in seconds. The timeframe is stated as 2 times throughout study completion, every 1 hour during the 2 hour protocol. The record does not explain whether or how repeated measurements were combined for the posted arm values.
Alongside the primary outcome, the registry lists Timed up and go Test Time and Gait Symmetry Index as secondary outcomes. It reports 3 outcome measures overall but gives no posted analysis results for the two secondary outcomes. The analysis count is 0. The registry record does not report an analysis population, a statistical analysis plan, details of allocation concealment, or further information on how the sequential order was managed. Those omissions limit the ability to assess the design beyond the features explicitly recorded.
The study is marked completed. The recorded start is 2016-09 and the primary completion is 2017-04. The sponsor is Angela DeCandia. The registry lists phase as NA. These administrative details describe the registered study record; they do not add information about the conduct or statistical validity of the comparison.
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.
Sidekicks
| Stage | Sequential Change of Intervention |
|---|---|
| STARTED | 1 |
| COMPLETED | 1 |
| NOT COMPLETED | 0 |
Conventional Prostheses
| Stage | Sequential Change of Intervention |
|---|---|
| STARTED | 1 |
| COMPLETED | 1 |
| NOT COMPLETED | 0 |
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.
| Characteristic | Unit | Sequential Change of Interventions |
|---|---|---|
| Participants analysed | 1 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 41 (SD 0) |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 1 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | participants | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Average Speed for 10 Meter Walk Test, measured over 2 times throughout study completion (every 1 hour during the 2 hour protocol).
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | m/s |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint, Average Speed for 10 Meter Walk Test, expresses the distance covered over the timed walk relative to the time taken. Its unit is m/s. The registry describes an unassisted 10-m walk with a running start, with time recorded for each pass and average speed calculated for each pass. It states that average speed was chosen because it is more reliable and representative than instantaneous gait speed, which may not be maintained consistently throughout the walk.
The timeframe is recorded as 2 times throughout study completion, every 1 hour during the 2 hour protocol. The description says one pass was completed with each set of prosthetic feet. It does not specify how repeated measurements were summarized into the single arm values, or report the underlying pass-level measurements.
Speed is a continuous measure, so a numerical value can describe the recorded performance in each arm. However, a useful comparison also needs information about variability and the study design’s handling of repeated observations. The registry posts 0.57 m/s for Stubbies and 0.53 m/s for Sidekicks, with n=1 in each arm, and gives no dispersion estimates or confidence intervals. These summaries therefore describe the recorded arm values but do not quantify the precision of a difference between prosthetic conditions.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry posts average 10-meter walk speeds of 0.57 m/s for Stubbies and 0.53 m/s for Sidekicks. Each arm has n=1. The figures are descriptive summaries, not a reported inferential comparison. No confidence interval, p-value, or sponsor analysis result is posted, and the registry reports 0 analyses. The two numeric values can be read as the recorded arm summaries, but the record does not support a claim about the size or precision of a population-level contrast.
The analysis status also matters. The registry identifies the endpoint kind as count other and indicates that values are missing or not estimable for a two-arm comparison for this endpoint. It also says the endpoint is not reduced to one comparison. Thus, the posted arm values should not be mistaken for an estimated treatment effect or an inferential result. The record does not explain why a two-arm comparison was not estimable.
With one participant recorded in each arm, there is no meaningful basis in the registry for estimating between-participant variability. Dispersion and interval estimates are absent. A confidence interval, in general, describes the range of values compatible with an estimate under a specified statistical model and its assumptions. Without a reported comparison estimate and the information needed to quantify uncertainty, the precision of a contrast cannot be judged from the arm summaries alone.
The study’s sequential crossover description raises a design consideration: measurements from the same participant under different conditions may be paired rather than independent. General statistical practice would account for such within-participant structure when estimating a contrast. The record does not report the participant-level paired measurements, the handling of repeated walks, or an analysis method, so it is not possible to determine how those features were treated. It would not be appropriate to infer a paired effect from the two arm-level values.
The stated research aims included gait velocity, exertion, and balance. The primary endpoint covers average walking speed. The two listed secondary outcomes are Timed up and go Test Time and Gait Symmetry Index, but their results are not reported in the registry record. The record does not post a numerical result for exertion or balance. Therefore, the posted primary endpoint values address only a limited part of the broader stated question.
Planning illustrations, if considered, are not observed power and do not repair the absence of an estimable comparison. The recorded sample-size assumptions describe a planning approach based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is a stated fraction of the observed effect. Such planning calculations are illustrative rather than evidence that the trial had adequate power. In this record, no inferential comparison is posted, so the observed arm values should remain descriptive.
9. Statistical Methods Explained
Randomization is a method for assigning study conditions by chance, intended in general to reduce systematic differences between groups. The registry marks allocation as RANDOMIZED. That label does not by itself establish how the sequence was generated, whether allocation was concealed, or how the actual order was carried out; those details are not reported in the registry record. Masking is listed as NONE, so the study is recorded as non-masked. The record does not describe any procedures to reduce expectation or measurement effects.
What does the sequential crossover description imply?
In a crossover design, a participant receives more than one condition, so each participant can contribute measurements under multiple conditions. In general, a within-participant comparison can account for stable characteristics shared across those measurements. It also requires attention to the order of conditions, possible carryover, and repeated measurements. These are general design considerations, not claims about what occurred in this study. The registry calls the model sequential and describes a sequential crossover, with conventional stubby prostheses used for baseline measures and Sidekicks used as the intervention. It does not report how order effects or carryover were assessed, or how repeated observations were analyzed.
The registry’s arm summaries list n=1 for Stubbies and n=1 for Sidekicks, while enrollment is 1. In a sequential crossover, those arm counts need not represent separate groups of participants; the record’s arm description indicates the conditions were used sequentially. However, the record does not provide a participant flow or a more detailed account of how enrollment and arm counts relate. For that reason, the arm summaries cannot be treated as evidence of two independent groups.
What does the endpoint measure?
The primary endpoint is average speed in m/s on the 10 Meter Walk Test. Its description specifies a 10-m distance, unassisted walking, and a running start. Recorded time is used to calculate average speed for each pass. General statistical reasoning distinguishes this average over a defined distance from instantaneous speed at one moment. The registry says average speed was selected as more reliable and representative because instantaneous gait speed may not be maintained consistently over the walk. The record does not report the raw times or pass-level speeds.
The timeframe is written as 2 times throughout study completion, every 1 hour during the 2 hour protocol. The registry does not explain how repeated observations were summarized into the posted arm values. When repeated measures are collected, general methods may model the correlation among measurements from the same participant; treating correlated observations as independent can misstate uncertainty. The analysis method is not reported in the registry record, so no particular repeated-measures method can be attributed to this study.
Why are uncertainty estimates important?
An arm mean or summary gives a central value, while dispersion describes how values vary. A confidence interval communicates uncertainty around an estimated quantity under a specified model. In general, these measures help readers distinguish the numerical estimate from its precision. Here, the registry reports a value for each arm but no dispersion or confidence interval. With n=1 shown in each arm and no participant-level information, the record does not enable an independent assessment of variability or a precise comparative estimate.
A p-value, in general, summarizes how unusual data would be under a specified null hypothesis and model; it is not a measure of clinical importance or the probability that a hypothesis is true. No p-value or test result is posted. The registry reports 0 analyses, and indicates that values are missing or not estimable for a two-arm comparison for this count other endpoint. Consequently, there is no reported inferential result to interpret. The descriptive arm values should not be converted into an unreported test or effect estimate.
What do the planning assumptions mean?
The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect specified as a fraction of the observed effect. General sample-size planning uses assumptions about the effect, variability, error rates, and design to illustrate the amount of information that might be needed for a future study. These calculations are not evidence about the probability that the completed study detected an effect. In particular, a planning illustration based on an observed effect is not observed power. The registry does not report its own sample-size justification, and no planning output values are stated in the record.
Multiplicity refers generally to the increased chance of false-positive findings when several hypotheses or outcomes are tested. This study lists 3 outcome measures overall, including the primary speed endpoint and the two named secondary outcomes. A multiplicity adjustment or testing hierarchy is not reported in the registry record. Without posted analyses, there is also no set of p-values or estimates to evaluate for multiplicity. The number of listed outcomes alone does not reveal what statistical procedures were planned or performed.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 3 outcome measures overall: the primary Average Speed for 10 Meter Walk Test and two secondary outcomes, Timed up and go Test Time and Gait Symmetry Index. It reports 0 analyses. Results for the secondary outcomes are not reported in the registry record. No multiplicity strategy, such as a testing hierarchy or adjustment for multiple comparisons, is reported. In general, multiplicity matters when several outcomes or hypotheses are tested because the chance of at least one false-positive result can increase. The record does not establish which outcomes were analyzed or whether any adjustment was used.
The registry does not report a prespecified statistical analysis plan, an analysis population, or rules for inclusion and exclusion of observations. It also does not report the amount or pattern of missing data, how missing observations were handled, or whether any imputation was used. For the primary endpoint, it specifically indicates that values are missing or not estimable for a two-arm comparison. This does not establish why a comparison was unavailable, and it should not be taken as evidence of a particular missing-data mechanism.
The analysis population is important in general because the set of participants included in a calculation can affect the interpretation of a result. The record’s enrollment of 1 and arm counts of n=1 do not supply enough detail to reconstruct an analysis population or the handling of measurements across the sequential conditions. No participant-level data or analysis descriptions are reported. Accordingly, neither missing-data assumptions nor the effects of analytic choices can be assessed from the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Stubbies | 0 | 1 | 0.0% |
| Sidekicks | 0 | 1 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Stubbies | 0 of 1 |
| Sidekicks | 0 of 1 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Stubbies | 0 of 1 |
| Sidekicks | 0 of 1 |
The registry reports safety counts separately for Stubbies and Sidekicks. In each group, 1 participant was at risk for serious adverse events and 0 serious adverse events were recorded. In each group, 1 participant was at risk for other adverse events and 0 other adverse events were recorded. Deaths are listed as 0 in each group. No top serious adverse-event terms are listed.
These are event counts in a very small registered study, not estimates of the frequency of harms in a broader population. A zero count means that no event was recorded in the listed group during the registry’s reporting; it does not establish that an event is impossible or that the groups have identical safety profiles. The record does not provide additional detail about event definitions, monitoring procedures, or the period covered by safety follow-up. The counts should therefore be read as limited descriptive information, not as a comparative safety analysis.
12. What the Result Does, and Does Not, Mean
The posted primary outcome summaries are 0.57 m/s for Stubbies and 0.53 m/s for Sidekicks, with n=1 for each. They show the values entered for the two conditions in the registry. They do not, on their own, establish a reliable difference between conditions, the size of a population-level effect, or the precision of any contrast. No confidence interval, p-value, dispersion estimate, or two-arm analysis result is posted.
The broader stated aims concerned gait velocity, exertion, and balance. Average 10-meter walk speed is the primary endpoint and speaks to the speed component. The registry also names Timed up and go Test Time and Gait Symmetry Index as secondary outcomes, but their results are not reported in the registry record. Although the study description states expectations about balance on level and gravel surfaces and perceived exertion, the registry does not post numerical results for those outcomes. The posted primary values therefore do not answer every stated research question.
General statistical interpretation separates a descriptive observation from an inference about a wider population. Inference requires a defined comparison and an assessment of uncertainty that reflects the design and data. Here, the registry identifies the outcome as not estimable for a two-arm comparison and reports 0 analyses. It does not report the analysis method or participant-level measurements needed to reconstruct a paired crossover comparison. The results therefore do not support a conclusion about whether one prosthetic condition is better or worse.
Likewise, planning calculations cannot turn these descriptive summaries into evidence of power or certainty. Sample-size illustrations are planning aids based on stated assumptions; they are not observed power and do not substitute for a reported estimate with uncertainty. The registry does not report its own sample-size justification. The appropriate reading is narrow: the record contains arm-level speed summaries and limited safety counts from a study with enrollment of 1, alongside no estimable two-arm endpoint comparison.
13. Why This Trial Matters Statistically
This trial is statistically notable because its registered design and posted results illustrate the distinction between collecting measurements under two conditions and producing an estimable comparison. The registry describes a randomized, non-masked, sequential crossover and records conventional stubbies for baseline measures followed by articulated Sidekicks as the intervention. Yet it reports one participant enrolled, arm summaries with n=1 each, and no analysis results. A design label alone cannot supply the missing comparison estimate or its uncertainty.
The endpoint is a continuous gait-speed measure, and the registry gives its units and calculation description. That makes the measurement concept clear, but the posted arm values do not disclose the participant’s underlying measurements, their variability, or how observations taken at different times were combined. In general, a crossover design can use within-person contrasts, but that requires an analysis that respects pairing and repeated measurements. The registry record does not report such an analysis.
The case also highlights why statistical precision and outcome scope matter. A central value without a dispersion estimate or confidence interval does not show how precisely an effect is known. And the primary speed endpoint does not represent all of the broader aims concerning balance and exertion. The registry names secondary outcomes, but their results are absent. These distinctions help readers avoid treating a small descriptive record as a conclusive test of the study’s stated expectations.
Finally, safety counts of zero in groups with one participant at risk are observations, not a broad estimate of safety. The record offers a useful example of how to read registered outcome summaries conservatively: identify the design, distinguish arm values from an effect estimate, check whether uncertainty and analyses are posted, and limit conclusions to the information the record contains.
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 most direct limitation is enrollment of 1. Although the registry gives summaries for both conditions, each arm has n=1 and the record does not supply participant-level data. It therefore provides no basis for assessing between-person variability or reconstructing the within-participant contrast implied by the sequential crossover description. The registry also marks values as missing or not estimable for a two-arm comparison and reports 0 analyses.
No dispersion estimate, confidence interval, p-value, or inferential comparison is posted for the primary endpoint. The record does not explain the reason a two-arm comparison was not estimable, nor how repeated measurements within the 2 hour protocol were combined. The measurement description includes repeated timing, but the method for handling those measurements is not reported in the registry record.
The design information is limited. Allocation is marked randomized and masking none, while the study model is sequential and the arm description refers to a sequential crossover. The sequence-generation and concealment procedures, order management, assessment of carryover, and analysis of paired data are not reported in the registry record. These details matter when interpreting measurements taken under more than one condition.
The outcome record is also incomplete relative to the stated aims. Two secondary outcomes are listed, but their results are not reported in the registry record. No numerical result for exertion or balance is posted. The record does not report a statistical analysis plan, multiplicity procedures, analysis populations, missing-data handling, or the study’s own sample-size justification. The safety counts are limited to one participant at risk per condition. Collectively, these omissions constrain interpretation to the descriptive information that is actually recorded.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Comparative Analysis Between College Park Sidekick Feet and Conventional Stubby Prosthesis — NCT02921295.
- Registry record last updated 2018-06-21; status last verified 2018-04.
- Results first posted 2018-05-24.
- 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.
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18. Record Summary
NCT02921295 is a completed, randomized, non-masked study with a sequential model. The registry records enrollment of 1 and compares conventional stubby prostheses with College Park Sidekick articulated stubbies. Its primary endpoint is average speed on the 10 Meter Walk Test, measured in m/s, with a timeframe described as 2 times throughout study completion, every 1 hour during the 2 hour protocol.
The posted arm values are 0.57 m/s for Stubbies and 0.53 m/s for Sidekicks, with n=1 in each arm. The registry reports no analyses and indicates that a two-arm comparison is not estimable for the primary endpoint. It lists Timed up and go Test Time and Gait Symmetry Index as secondary outcomes, without posted results. Safety counts show 0 serious adverse events, 0 other adverse events, and 0 deaths in each group, with 1 at risk in each.
The record does not report an inferential comparison, uncertainty estimates, analysis plan, or detailed handling of repeated observations. Its posted results are therefore descriptive and do not establish a precise comparative effect.