Personalizing MPK Prescription: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Personalizing MPK Prescription (NCT06399471), a na na study. The primary outcome is Ten Meter Walking Test.

2. Clinical Question

The study addresses a prosthetic-selection problem described in the registry summary: clinicians may rely on experience and intuition when selecting a microprocessor knee, while studies may group different knee models together. The stated aim is to assess individual knees rather than treating them as a single undifferentiated category.

This is a question about performance on a walking-speed measure under the study conditions. The endpoint alone would not capture every outcome relevant to prosthetic use. The registry also lists measures concerning stance-time asymmetry, narrow-beam walking, reported falls, physiological cost, and speed on stairs and ramps. Their presence indicates a broader set of outcomes, but does not establish that results were reported or that any particular knee performed better.

Because each participant wore all three knees, a comparison could use within-participant information. Such a comparison is not equivalent to a conventional parallel-group trial with separate treatment and control groups. The registry does not report numerical endpoint results or enough analysis detail to assess how the knee conditions were compared.

3. Trial Design

Personalizing MPK Prescription is a completed, single-group device study sponsored by Georgia Institute of Technology. The registry lists enrollment of 11 participants with transfemoral amputation. Its record gives a start date of 2021-10-25 and a primary completion date of 2023-10-02. The phase is recorded as NA, and masking is listed as none.

The intervention is described as a microprocessor prosthetic knee. The arm description refers to randomization to the C-Leg 4.0, Rheo Knee, and Power Knee, while the primary-outcome population description states that each participant wore all three knees. Allocation is listed as NA, and the record does not explain how the sequence of conditions was determined. It also does not describe a separate concurrent control group. The record cautions against treating the arms as a like-for-like randomized control comparison.

One participant withdrew after consenting and did not complete any of the conditions. That leaves the number of participants who completed every condition unclear from the registry record; condition-specific completion details are not reported in the registry record. The safety listings use different numbers at risk across the knee groups, so the available safety denominators should not be taken as evidence that the same participants contributed to every listed outcome.

The primary measure is the Ten Meter Walking Test, specified as mean walking speed in meters per second, with standard deviation as the dispersion measure and a timeframe of 1 month. The registry lists 12 outcome measures and 20 analyses. It also names secondary measures covering gait symmetry, balance-related walking, falls, physiological cost, and stair and ramp speeds. The precise analysis plan, order of testing, and handling of repeated measurements 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.

Before assignment: Knee condition order was randomized prior to enrollment.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: 1 participant did not complete any of the conditions due to self withdrawal after consenting. Each participant wore all three knees during this trial.

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.

6. Primary Endpoint

The registry lists the primary outcome as Ten Meter Walking Test, measured over 1 month.

The Ten Meter Walking Test measures self-selected walking speed over ten meters of over-ground walking. The registry expresses the endpoint in meters per second and specifies a mean with standard deviation. Walking speed is a continuous measure: it can take values across a range rather than placing participants into categories such as success or failure.

As a general statistical point, a mean describes the average measurement in a group or condition, while the standard deviation describes how spread out individual measurements are around that average. Reporting both can help readers distinguish the typical observed level from the variability among participants. Neither quantity, by itself, shows whether differences between knee conditions are statistically persuasive or clinically important.

A self-selected pace reflects walking at a participant's chosen speed rather than a speed imposed by the test. The registry describes the measure as walking over ground, making it a direct performance measure under that test setting. It does not capture every aspect of mobility, safety, comfort, or day-to-day prosthetic use. The record names other outcomes, including reported falls and stair and ramp speeds, but their results are not reported in the registry record.

The primary timeframe is 1 month. The registry does not report the numerical mean, standard deviation, difference between knee conditions, confidence interval, or statistical test for this endpoint. Therefore, the endpoint's observed performance and the precision of any comparison cannot be assessed from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods turn recorded measurements into estimates that can be interpreted in light of variability and study design. The registry specifies a continuous primary endpoint summarized by a mean and standard deviation. It does not report the endpoint values or the method used to compare conditions, so the concepts below explain how such data are generally interpreted rather than describing an analysis confirmed in this study.

What a mean and standard deviation describe

For a continuous outcome, the mean is the arithmetic average of the recorded values within a defined group or condition. The standard deviation describes the spread of individual values around that mean. A mean is useful for describing the average measured walking speed, but it can conceal differences among participants. The standard deviation adds information about that variability; it is not the uncertainty interval for the mean and does not, on its own, quantify the uncertainty in a comparison.

In a within-participant study, each person's measurements under different conditions are linked. A comparison can use the change within each participant, rather than comparing unrelated groups. The variability of those within-person differences is important to the precision of the estimate. Treating repeated measurements as independent when they are correlated can misstate uncertainty. The registry's analysis method and correlation handling are not reported in the registry record.

How to read an estimate and confidence interval

In general, an estimated difference describes the observed separation between conditions according to a chosen analysis. A confidence interval gives a range of values compatible with the data and analysis assumptions at a stated confidence level. A narrower interval indicates greater precision, while a wider interval indicates more uncertainty. A confidence interval can help readers assess both the possible size of a difference and the uncertainty around it. No comparison estimate or confidence interval for the primary endpoint is reported in the registry record.

A p-value, when reported, describes how unusual the observed data or more extreme data would be under a specified null hypothesis and model. It does not measure the probability that the null hypothesis is true, the size of an effect, or its practical importance. The registry record does not report a primary-endpoint p-value or identify the test used. Consequently, no claim about statistical significance can be made from the information in the record.

Repeated conditions and study structure

The record says each participant wore all three knees. In general, this arrangement can reduce the impact of stable differences between people because each participant can serve as their own reference across conditions. It also makes the sequence and spacing of conditions relevant: learning, fatigue, or other time-related influences could affect measurements if they vary by order. The registry does not report the condition sequence, any washout procedures, or methods used to address order or period effects. These possibilities should not be treated as confirmed features or problems of the study; the relevant details are simply not reported in the registry record.

The record describes the study as single-group and lists allocation as NA, while the arm description uses the term randomization and the primary-outcome description says everyone wore all three knees. Those statements do not establish the exact allocation procedure or testing sequence. The registry also cautions that the arms are not a like-for-like control comparison. A statistical interpretation should therefore avoid assuming a conventional randomized comparison between independent groups.

Uncertainty, sample size, and planning

The registry's sample-size assumptions describe a planning illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. This is a hypothetical planning calculation, not observed power and not proof that the study was designed with those assumptions. The numerical planning outputs and the effect estimate on which they depend are not reported in the registry record. The trial's own sample-size justification is not reported in the registry record.

More generally, a planning calculation asks how many participants might be needed to detect an assumed effect under stated assumptions. Its answer depends on the outcome's variability, the effect considered meaningful, the analysis, and other design choices. If the assumed effect differs from the true effect, the planning illustration may not reflect the precision achieved. Such a calculation should not be interpreted as evidence that the observed study had a particular probability of detecting an effect.

Over-dispersion is a general issue when observed variation exceeds what an assumed statistical model allows. If a model underestimates variability, its uncertainty estimates may be too small and its intervals too narrow. The registry does not report whether over-dispersion was assessed or relevant to the primary endpoint; given the missing endpoint results and analysis details, no assessment is possible.

The registry lists 12 outcome measures and 20 analyses. A complete statistical report would normally clarify which outcome and analysis were primary, how repeated measurements were modeled, what uncertainty measures were calculated, and whether multiplicity was addressed. Those details are not reported in the registry record. The listed summary measure alone does not identify the full statistical model.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 12 outcome measures and 20 analyses. Multiple outcomes and analyses can create multiplicity: when many statistical questions are examined, the chance of finding at least one apparently notable result can rise, even if none represents a reliable underlying difference. This is a general statistical concern, not a claim that the study's findings are misleading. The registry record does not report a procedure for adjusting for multiplicity, a hierarchy among secondary outcomes, or whether analyses were prespecified.

The Ten Meter Walking Test is identified as the primary outcome, but the registry does not report numerical results or a detailed analysis plan. It does not describe how the primary comparison was defined, how repeated observations were handled, or whether secondary analyses were exploratory. The statistical analysis plan is not reported in the registry record.

One participant withdrew after consenting and did not complete any of the knee conditions. This identifies a known source of incomplete participation, but the record does not state how missing observations were handled in analyses or how many participants contributed to each endpoint. The analysis population, reasons for any other missing measurements, and any sensitivity analyses are not reported in the registry record.

In general, missing-data methods rely on assumptions about why measurements are absent. A complete-case analysis, for example, uses only participants with the required measurements; other approaches may use additional information under explicit assumptions. Neither approach can be attributed to this study from the registry information. The differing numbers at risk in the safety listings also do not establish the primary endpoint's analysis population.

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.

The registry lists serious adverse events, other adverse events, and deaths for the three knee groups. For the C-Leg 4.0 and Rheo listings, 10 participants are recorded as at risk in each category; for the Power Knee listing, 11 are recorded as at risk. The event counts are zero for serious adverse events, zero for other adverse events, and zero for deaths in each listing. No serious adverse-event terms are listed.

These are descriptive counts for the participants included in each safety listing. The numbers at risk differ across groups, and the record does not explain the denominator difference or provide further detail about safety follow-up. The figures should therefore be read as the registry's recorded counts, not as evidence that the same participants contributed to all three listings.

In general, observing no events in a study does not establish that an event cannot occur or that risk is absent. Event counts are especially limited as a basis for estimating uncommon harms when the number of observed participants is small. The registry does not report additional safety analyses, event timing, or a detailed safety-analysis method.

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

The record establishes that a completed study examined microprocessor prosthetic knees in individuals with transfemoral amputation and specified self-selected ten-meter walking speed as its primary outcome. Each participant is described as having worn all three knees. The record also identifies a set of secondary mobility and safety-related measures and gives descriptive safety counts.

It does not report the observed primary endpoint values or numerical comparisons among knees. Without those results, readers cannot determine the direction or size of any difference in walking speed, how variable the measurements were, or how precisely a comparison was estimated. No conclusion about relative performance follows from the study title, stated aim, or endpoint selection alone.

The registry record also does not establish whether any observed difference would be important in practice. Statistical evidence and practical importance are distinct: a precise estimate can still be small, and an apparently large estimate can be uncertain. Assessing either requires the actual estimates and their uncertainty, which are not reported in the registry record.

The findings, if reported elsewhere, would need to be interpreted in light of this study's participant group, within-participant exposure to the knees, and unspecified condition sequence and analysis methods. The registry does not provide details that would support generalizing results to people outside the described population or to circumstances not represented by the study.

The safety listings record zero events in the listed categories, but those counts do not demonstrate an absence of risk. Overall, the registry record describes the research question and selected design features, while leaving the numerical efficacy findings and important analysis details unreported.

13. Why This Trial Matters Statistically

This study is statistically interesting because it focuses on differences among individual microprocessor knees rather than treating them as one combined category. The registry summary describes a clinical selection problem in which choices may rely on clinician experience. A structured comparison of individual devices could address that question, but its value depends on transparent outcome reporting and an analysis suited to the study design.

Having each participant wear all three knees creates a repeated-measures structure. In general, this permits comparisons that account for each participant's own measurements across conditions. It also makes within-person correlation, condition order, and completeness of measurements important to interpretation. The registry identifies the repeated exposure but does not report the sequence or analysis details needed to assess those features.

The primary outcome is a continuous measure of walking speed, while the registry lists additional outcomes spanning other aspects of mobility and function. That breadth can describe more than a single performance dimension, but multiple outcomes also make prespecification and multiplicity procedures relevant. The record lists 12 outcome measures and 20 analyses, without reporting how those analyses were prioritized or adjusted.

Most importantly, a study's statistical question cannot be answered from its design description alone. The registry's lack of numerical primary results means that readers cannot examine an effect estimate, its variability, or its precision. Complete reporting would allow readers to distinguish the observed pattern from uncertainty and to assess whether the analysis matches the repeated-condition design.

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 main limitation for interpreting this registry record is that numerical results for the primary walking-speed endpoint are not reported in the registry record. Condition-specific means and standard deviations, comparison estimates, confidence intervals, and p-values are absent. Without those quantities, the size and precision of any difference cannot be evaluated.

The participant group is small in absolute terms, with enrollment of 11, and one participant withdrew after consenting without completing any knee condition. This limits the amount of information available for comparisons, although the exact number analyzed for each outcome is not reported in the registry record. The record does not describe other missing measurements or how incomplete data were handled.

Each participant wore all three knees, but the registry does not specify the order of conditions or report whether analyses considered order, learning, fatigue, or other period-related influences. These are general considerations for repeated-condition designs, not documented events in this study. Allocation is listed as NA, and the record itself cautions that the arms are not a like-for-like control comparison.

The registry lists multiple outcomes and analyses but does not report a statistical analysis plan, multiplicity approach, or detailed analysis populations. The trial's sample-size justification is not reported in the registry record. Although the assumptions for a planning illustration are stated, the numerical output and the observed effect used for that illustration are not reported in the registry record. The safety listings also have differing numbers at risk and provide limited detail about follow-up.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Personalizing MPK Prescription — NCT06399471.
• Registry record last updated 2024-11-14; status last verified 2024-11.
• Results first posted 2024-11-14.
• 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

NCT06399471, Personalizing MPK Prescription, is a completed single-group device study sponsored by Georgia Institute of Technology. It enrolled 11 individuals with transfemoral amputation and examined the C-Leg 4.0, Rheo Knee, and Power Knee. The registry states that each participant wore all three knees.

The primary outcome is mean self-selected walking speed over ten meters, measured in meters per second at 1 month, with standard deviation specified as the measure of dispersion. One participant withdrew after consenting and did not complete any conditions. The registry lists 12 outcome measures and 20 analyses.

Numerical primary-outcome results and details of the statistical analysis are not reported in the registry record. The listed safety counts show no serious adverse events, other adverse events, or deaths in the knee groups.