Repair of Soft Tissue Defect of the Finger Using the Heterodigital Neurocutaneous Island Flap: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Repair of Soft Tissue Defect of the Finger Using the Heterodigital Neurocutaneous Island Flap (NCT01778296), a na na study. The primary outcome is Discriminatory Sensation of the Flap.

2. Clinical Question

3. Trial Design

The registry record identifies NCT01778296 as a completed, single-group study of the neurocutaneous island flap for repair of a finger soft-tissue defect. Enrollment is listed as 12. The record gives a start date of 2008-01 and a primary completion date of 2012-03. The study is not described as a randomized comparison: allocation is listed as NA, and masking is listed as NONE. There is one surgical-flap group and no stated comparator.

The flap is described as based on the dorsal branch of the digital nerve. The brief summary explains the rationale in anatomical terms: a dorsal digital island flap can repair a defect of an adjacent finger, while its limited pedicle length restricts use for more distal defects; a heterodigital neurocutaneous island flap is described as an alternative. This explanation is the stated rationale, not evidence of comparative benefit.

The primary outcome is discriminatory sensation of the flap, assessed with the static two-point discrimination test. The outcome is specified as a mean, with standard deviation as its dispersion measure, in millimeters. The planned timeframe is 18 months to 24 months, described as a single assessment at final follow-up. Cold intolerance is listed as a secondary outcome. Although two outcome measures are recorded, the registry record does not report their numerical results or the number of participants contributing data to them.

The record does not report a statistical analysis plan, a sample-size justification, or a detailed description of the study population. The study’s completed status does not establish that all enrolled participants contributed to each outcome; the analyzed population and missing outcome data 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: No wash out, run-in or transition happened in our study.

Overall Study

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: The participants with a follow-up period ≥18 months were included for this Baseline Measure.

6. Primary Endpoint

The registry lists the primary outcome as Discriminatory Sensation of the Flap, measured over 18 months to 24 months.

The primary endpoint is discriminatory sensation of the flap, measured in millimeters with the static two-point discrimination test. The test assesses the minimum distance at which a participant can distinguish the presence of two needles. The record says the test point was at the center of the flap. Each area was tested 3 times with a Discriminator, and two out of 3 correct answers were treated as proof of perception before moving to a lower distance. Testing stopped at 4mm, which the record considered normal.

The endpoint is intended to quantify tactile discrimination at the flap rather than to provide a broad measure of hand function. The registry describes the modified American Society for Surgery of the Hand guidelines as classifying measurements as excellent (<6 mm), good (6-10 mm), fair (11-15 mm), or poor (>15 mm). These are the record’s interpretation bands; the registry does not report the observed mean or standard deviation, nor how the measurements were distributed across these categories.

Two-point discrimination is used because it provides a defined sensory task and a distance-based measure. As a general statistical point, reporting a mean alongside a standard deviation can describe both the average measurement and its variability, although the mean alone does not show the range or shape of individual observations. The result for this endpoint is not reported in the registry record, so the measure cannot be interpreted from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The available outcome specification identifies a continuous measurement and says the planned summary is a mean with standard deviation. It does not report the outcome value or any statistical analysis. This distinction matters: a clearly defined measurement procedure is not the same as a reported estimate, and neither a mean nor its uncertainty can be reconstructed from the description alone.

What does a mean describe?

As a general statistical explanation, a mean is a measure of the center of a set of numerical observations. In this study, the observations would be static two-point discrimination distances, expressed in millimeters. A mean can condense multiple measurements into a single summary, but it does not show whether observations cluster closely around that value, whether a small number of observations are unusually high or low, or how many participants had measurements in each named category.

The standard deviation is a measure of spread around the mean. A larger standard deviation indicates more dispersion in the observations, while a smaller one indicates tighter clustering. It is not a confidence interval and does not directly describe uncertainty in the estimated mean. The registry record specifies standard deviation as the dispersion measure but does not report its value. Without the mean, standard deviation, and analyzed sample size, the primary outcome cannot be quantitatively interpreted.

How is two-point discrimination measured?

The registry describes a sensory test based on the smallest distance at which a person can perceive two needles rather than one. The test point is the center of the flap. Each area is assessed 3 times, and two out of 3 correct answers count as proof of perception before the tester proceeds to a lower distance. The record says testing stops at 4mm and considers this normal. It also describes the modified American Society for Surgery of the Hand categories: excellent (<6 mm), good (6-10 mm), fair (11-15 mm), and poor (>15 mm).

These instructions provide operational detail about how the endpoint was assessed. They do not report whether the same assessor tested every participant, whether assessment was blinded, or how measurements were handled when a participant did not meet the response rule. Such procedures are not reported in the registry record. The listed masking status is NONE, but the record does not elaborate on assessor masking specifically.

Why does the single-group design matter?

The record lists a single group, with allocation NA and no comparator. Therefore, the primary outcome is not an estimate of a difference between groups. A between-group treatment effect would require a comparison that this design does not specify. General statistical reasoning also distinguishes a group’s outcome at follow-up from the change attributable to an intervention: without a reported baseline measurement or a control group, other influences cannot be separated using a treatment contrast.

One group can still be described using a mean and standard deviation if the observations are reported. But no such summary appears in the registry record. The study’s enrollment of 12 is not automatically the denominator for the primary endpoint. Follow-up, missing measurements, and the actual analysis population are not described, so the count contributing to the endpoint is unknown.

What can a confidence interval add?

In general, a confidence interval gives a range of values compatible with an estimate under a statistical model and its assumptions. Its width conveys precision: a narrower interval indicates greater precision under those assumptions, while a wider interval indicates less. A confidence interval would not correct for an uncontrolled design, selective missingness, measurement error, or other sources of bias. No confidence interval is reported for the primary endpoint, and there is no reported estimate from which to assess one.

Likewise, a p-value would address a specified statistical hypothesis under a model; it would not itself measure the size or clinical importance of an outcome. The registry record reports no p-value, hypothesis test, or inferential analysis. The number of analyses listed is 0. The absence of a reported test should not be interpreted as evidence that the endpoint met or failed a criterion.

How should planning calculations be read?

The registry’s planning assumptions describe an illustration computed from an observed effect, not the design used for this single-group study. The illustration is characterized as two-sided, with significance level 0.05, equal allocation between two arms, and a normal approximation; it considers a detectable effect stated as a fraction of the observed effect. Those are planning assumptions, not observed trial outcomes. The record does not report the trial’s own sample-size justification. Planning calculations are not observed power, and an illustration built around two arms does not change the study’s single-group design.

For continuous outcomes, general planning methods depend on the effect to be detected, variation in the outcome, the allocation structure, and the chosen error-rate assumptions. No new sample-size estimate can be inferred from the information in the registry record. The planning assumptions alone do not establish that the enrolled number was adequate, nor do they show that the primary endpoint was analyzed with a particular model.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Surgical Flap")
n   <- c(12)
m   <- c(8.3)
sp  <- c(1.6)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Surgical Flap  12  8.300  1.600  7.283  9.317

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures: discriminatory sensation of the flap as the primary outcome and cold intolerance as a secondary outcome. It does not report results for either measure. The number of analyses recorded is 0, and no statistical analysis plan, outcome hierarchy beyond the primary and secondary labels, or multiplicity adjustment is reported in the registry record.

Multiplicity is a general statistical concern when several outcomes or hypotheses are tested: conducting multiple tests can increase the chance of at least one apparently positive result under a null scenario. Whether and how to address that concern depends on the planned analyses and their purposes. Because the registry record does not report inferential results or a testing plan, it is not possible to determine whether multiplicity adjustments were planned or used. The presence of two registered measures alone does not establish that two hypothesis tests were performed.

Missing-data handling is also not described. The record gives an enrollment of 12, but does not report the number with an observed primary outcome, the number contributing to cold-intolerance assessment, reasons for missing measurements, or any imputation or sensitivity analysis. The completed study status does not show that all enrolled participants were analyzed. As a general matter, missing measurements can affect both the estimate and its precision, particularly if the availability of measurements is related to participants’ outcomes.

The analysis population is not reported in the registry record. There is no stated intention-to-treat, per-protocol, or other analysis set, and no account of exclusions. Since there is no randomized allocation, an intention-to-treat comparison is not described. These omissions limit assessment of how the registered outcomes were handled and whether the reported adverse-event denominators correspond to the endpoint analysis population.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

For the Surgical Flap group, the registry lists 12 participants at risk for serious adverse events and 0 participants affected. It also lists 12 at risk for other adverse events and 0 affected. The record does not list any top serious adverse-event terms. These entries describe what was recorded in the registry; they are not a comparison with another group, since no comparator group is reported.

The death count is not reported in the registry record. The adverse-event entries do not provide event definitions, follow-up completeness, event-level descriptions, or information about how events were collected. A count of 0 affected in the registry should therefore be read narrowly as the recorded count, not as proof that no events occurred or that no unrecorded events were possible. The adverse-event information also does not provide a numerical result for discriminatory sensation or cold intolerance.

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

The record describes a surgical approach and a planned way to measure sensation at the flap. It documents enrollment of 12 participants, a single surgical-flap group, and an intended final-follow-up assessment within 18 months to 24 months. It also provides procedural details for static two-point discrimination and lists cold intolerance as a secondary outcome. These registry entries describe the study’s design and registered outcomes, not the magnitude of any observed sensory outcome.

The primary endpoint result is not reported in the registry record. Accordingly, the record does not allow readers to determine the group’s mean discriminatory sensation, its variability, how measurements fit the stated categories, or the precision of an estimate. The cold-intolerance result is also not reported. No baseline sensory measurement or control group is described, so the record does not establish a change over time or a comparative treatment effect.

The registry records 0 serious adverse events and 0 other adverse events among 12 participants at risk in the surgical-flap group. These figures are useful as a description of the entered safety counts, but they do not demonstrate the absence of all possible harms. The record does not report deaths, event details, or completeness of safety follow-up.

More generally, a study’s completed status and a specified assessment method do not by themselves establish that an intervention caused a particular outcome. A single-group record can describe observations when results are available, but it cannot supply a randomized or controlled contrast that is not part of the design. Since numerical outcome analyses are absent, the posted information cannot support a conclusion about the level, precision, or comparative meaning of the primary endpoint. The trial’s own sample-size rationale and analysis plan are not reported in the registry record.

14. Why This Trial Matters Statistically

This study is statistically notable for the gap between a detailed endpoint procedure and the absence of a posted endpoint result. The registry specifies the sensory task, test location, response rule, stopping limit, summary measure, dispersion measure, and intended follow-up timeframe. Those details make clear what the primary outcome was intended to represent. Without a reported estimate, however, readers cannot quantify the observed sensation or its variability.

The single-group design also defines the kind of inference available. There is no randomized allocation or comparator, so the study does not provide a between-group treatment contrast. This matters when interpreting any descriptive outcome: a measurement in the flap group is not, by itself, an estimate of what would have happened under another approach. The registry record also does not report a baseline sensory value that would permit a documented within-participant change.

Enrollment is listed as 12, but the number analyzed for the primary and secondary outcomes is not reported. That distinction matters because precision depends on the observations actually included, not merely the enrollment figure. The record contains no reported mean, standard deviation, confidence interval, or analysis result with which to assess precision.

The outcome categories and the safety counts add useful context but cannot fill the result gap. Thresholds describe interpretation bands, while the registry gives no category counts. The adverse-event record lists zero affected participants in the recorded categories, but it does not provide event-level detail or a comparator. The record therefore illustrates why design, measurement, outcome reporting, and analysis population all need to be read together when judging what a clinical study can establish.

15. 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.

Several limitations specific to this record constrain interpretation. First, it describes a single group and no comparator. Allocation is listed as NA, masking as NONE, and the study model as single group. The study therefore does not provide a controlled comparison of the flap with another method. The registry does not report a baseline sensory measure, so it also does not document change from baseline.

Second, the primary outcome value and standard deviation are not reported in the registry record. The endpoint’s assessment procedure and category thresholds are described, but observed measurements and category counts are absent. Cold intolerance is listed as a secondary outcome, but its result is not reported either. The record gives no confidence interval, p-value, or inferential analysis.

Third, the registry lists enrollment of 12 but does not report the analyzed sample size for any outcome, missing data, reasons for missingness, or an analysis population. It is therefore unclear how many participants contributed to the intended follow-up assessment. The study is marked completed, but this does not resolve endpoint completeness.

Fourth, the record does not report eligibility criteria in detail, participant characteristics, assessor procedures beyond the test description, or a statistical analysis plan. The sample-size justification is not reported in the registry record. Although a planning illustration is described, its assumptions do not establish the study’s own design rationale or analysis. Finally, the safety record gives counts but no event-level descriptions, and deaths are not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Repair of Soft Tissue Defect of the Finger Using the Heterodigital Neurocutaneous Island Flap — NCT01778296.
• Registry record last updated 2024-02-14; status last verified 2012-05.
• Results first posted 2013-11-18.
• 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.

19. Record Summary

NCT01778296 is a completed, single-group study of a neurocutaneous island flap based on the dorsal branch of the digital nerve for repair of a finger soft-tissue defect. Enrollment is listed as 12, with no comparator and masking listed as NONE. The primary outcome is mean discriminatory sensation in millimeters, assessed using static two-point discrimination at final follow-up within 18 months to 24 months. Cold intolerance is listed as a secondary outcome.

The registry record describes the measurement procedure but does not report numerical results for either outcome, the analyzed population, missing data, or a statistical analysis. It records 0 serious adverse events and 0 other adverse events among 12 participants at risk; deaths are not reported in the registry record. The study’s own sample-size justification and analysis plan are also not reported.