Computed Tomography for Evaluating Supination-external Rotation Type Ankle Fractures: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Computed Tomography for Evaluating Supination-external Rotation Type Ankle Fractures (NCT02599441), a registered phase not stated study. The primary outcome is Medial Clear Space Distance in the Ankle Joint.

2. Clinical Question

Medial clear space is the named measurement of interest, rather than a reported clinical event or a time-to-event outcome. The record identifies a single-day baseline timeframe. It does not provide the definition of instability, a threshold for interpreting the measurement, or a numerical result establishing how the methods compared. Accordingly, the question can be described from the study objective and registered endpoints, but the posted record does not permit an estimate of the size or precision of any comparison.

3. Trial Design

The registry record describes a completed study sponsored by the State University of New York at Buffalo. Its title and brief summary describe a comparison of a novel weight-bearing cone-beam CT scan with gravity stress X-ray for assessing instability in supination-external rotation ankle fractures. The record lists 9 participants enrolled. The study start is recorded as 2016-02, and primary completion is recorded as 2017-02-02.

The recorded arm is titled “Ankle fracture cases,” and no arm description is posted in the registry record. The record explicitly does not describe a randomized comparison; allocation is not stated, and the arms are not a like-for-like control comparison. The planned two-arm assumptions attached to a sample-size illustration should therefore not be read as a description of the actual study design. The record does not explain whether or how measurements from the different imaging methods were matched within participants.

The primary outcome is medial clear space distance in the ankle joint, measured on weight-bearing CBCT. It is specified as a mean with standard deviation, in millimeters, at baseline in a single-day study. Two secondary outcomes are listed: medial clear space on gravity stress X-ray and medial clear space on standard X-ray. Three outcome measures are recorded in total. The registry record does not report the numerical outcome values, analysis methods, or participant-level analysis population.

Further design details—including eligibility criteria, recruitment procedures, masking, sample-size justification, and a detailed statistical plan—are not reported in the registry record. The study status is completed, but completion status alone does not provide results or establish how fully the planned assessments were carried out.

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

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 Medial Clear Space Distance in the Ankle Joint, measured over Baseline- single-day study.

The primary endpoint is medial clear space distance in the ankle joint, measured on weight-bearing cone-beam CT. The record specifies millimeters as the unit and describes the outcome as a mean with standard deviation. Its timeframe is baseline in a single-day study.

The study objective places the measurement in the context of assessing ankle stability in supination-external rotation fractures. In general, a continuous measurement can describe the size of a joint-space distance and can be summarized by its average and the variability of measurements around that average. The standard deviation describes spread among observed measurements; it is not itself a measure of uncertainty in the estimated mean. These are general statistical definitions, not reported findings from this study.

Medial clear space on gravity stress X-ray and on standard X-ray are listed as secondary outcomes, providing other imaging measurements relevant to the stated comparison. However, the registry record does not give a threshold for classifying a measurement as unstable, the measurement procedure, or any numerical results for the primary or secondary outcomes. It therefore does not show the observed mean, standard deviation, or a comparison estimate. The endpoint definition identifies what was to be measured, but by itself does not establish the clinical interpretation of a particular value or show how the imaging methods performed relative to one another.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous measurement: medial clear space distance in the ankle joint. The registry record specifies that it is measured on weight-bearing CBCT and reported as a mean with standard deviation, in millimeters. It also specifies a baseline, single-day timeframe. No numerical value for the mean or standard deviation is reported in the registry record, and no analysis of this endpoint is listed.

What do the mean and standard deviation describe?

In general, the mean is the arithmetic average of measured values. It gives a central summary on the measurement’s original scale. The standard deviation describes how dispersed individual measurements are around that mean. A small standard deviation indicates that the observed values lie relatively close to their average; a larger standard deviation indicates more spread. These are general explanations, not findings from this study. Since neither statistic is reported, the observed average and variability cannot be assessed.

How would a comparison of imaging measurements be interpreted?

In general, a comparison between methods would need to be defined in relation to the study’s measurement structure and research question. If an estimate of a difference were reported, its direction and size would describe the contrast on the measurement scale, while an uncertainty interval would indicate how precisely that contrast was estimated. The registry record does not state a comparison model, provide a difference estimate, or report an uncertainty interval. It also does not explain whether measurements from the methods were obtained in the same participants or how any relationship between measurements was handled. A particular paired or independent-samples method should not be inferred.

The registry lists medial clear space on gravity stress X-ray and medial clear space on standard X-ray as secondary outcomes. These outcomes identify additional measurements, but their inclusion alone does not specify whether the intended analysis was a direct comparison, a descriptive summary, or another approach. The record does not report their numerical values or explain how each outcome was analyzed.

What does the sample-size illustration represent?

The registry’s sample-size assumptions describe a planning illustration based on a fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. These assumptions are for the illustration, not a reported design feature of the trial. The record does not report a trial-specific sample-size justification or the observed effect needed to interpret the illustration. It also does not provide numerical participant targets for the illustration in the registry record associated with this record.

In general, a sample-size calculation uses assumptions about the effect to detect, variability, error rates, and design to estimate a planning target. An illustration built from an observed effect is not an observed measure of power and does not show the probability that the completed study detected an effect. The assumptions of equal allocation and two arms should not be confused with the record’s design description: allocation is not stated, and the study is not described as a randomized, like-for-like comparison. The record’s enrollment of 9 is the reported enrollment, not a statement that a target was met or that a particular power was achieved.

Why does the normal approximation matter?

In general, a normal approximation can simplify calculations by using a normal distribution as an approximation for the sampling behavior of an estimate. Its usefulness depends on the design, the data, and the assumptions behind the calculation. The registry’s mention of this approximation applies to its planning illustration; it does not establish that the outcome analysis used a normal model. The record does not provide distributions, diagnostic checks, or an analysis plan with which to assess modeling assumptions.

For continuous measurements, the shape of the observed data and the presence of unusual values can affect how well a mean and standard deviation summarize the sample. General alternatives may be useful for other data structures, but the registry record does not say that any alternative method was used or needed. Without posted values or an analysis description, there is no basis to characterize the data distribution, assess outliers, or judge model fit.

Finally, the registry lists zero analyses. That entry does not provide estimates or uncertainty measures to interpret. It limits what can be concluded from the posted record: the endpoint and general planning assumptions are described, but the statistical methods applied to observed outcome data are not reported in the registry record.

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("Ankle Fracture Cases")
n   <- c(9)
m   <- c(1.41)
sp  <- c(0.41)
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  Ankle Fracture Cases  9  1.410  0.410  1.095  1.725

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists three outcome measures: the primary medial clear space distance measured on weight-bearing CBCT, and secondary medial clear space measurements on gravity stress X-ray and standard X-ray. It lists zero analyses. No numerical outcome results, analysis population, or statistical plan are reported in the registry record.

Multiplicity is the general issue that arises when more than one outcome or statistical comparison is examined. Considering several outcomes can affect the chance of obtaining at least one apparently notable result by chance, depending on the analysis plan and interpretation. A prespecified approach can explain how multiple outcomes are prioritized or whether any adjustment is used. The record does not report a multiplicity strategy or whether any adjustment was planned or performed. With no listed analyses or numerical results, it is not possible to assess how multiple outcomes were handled.

Missing-data information is also not reported in the registry record. The enrollment is 9, but the record does not state how many participants had each imaging measurement, whether any observations were unavailable, how missing observations were handled, or whether reasons for missingness were recorded. A single-day baseline timeframe is specified for the primary outcome, but that does not establish that every enrolled participant completed the measurement.

The record does not define an analysis population or say whether analyses were intended to include all enrolled participants, only those with usable scans, or another group. The absence of a listed analysis is not enough to infer a particular handling of missing observations or to determine whether the primary endpoint was analyzed. These omissions prevent assessment of attrition, completeness, and the relationship between enrollment and the analyzed sample.

12. 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 record lists an adverse-event group titled “Ankle Fracture Cases.” It reports 9 participants at risk for serious adverse events and 0 affected, 9 at risk for other adverse events and 0 affected, and 0 deaths. No top serious adverse-event terms are listed.

These counts describe what is recorded in the registry for the listed group. They are not a comparison between randomized treatment arms: the study is not described as randomized, and the record does not identify like-for-like control arms. A zero count in the posted record means that no events are listed in that category for the group; it does not establish that every possible event was absent or that safety has been characterized comprehensively.

The registry record does not report the adverse-event definitions, collection procedures, observation period, or event-related analysis. The at-risk counts should not be treated as the number with complete safety follow-up unless that is stated, and it is not stated. These safety figures are separate from the imaging outcomes and do not provide evidence about comparative measurement performance.

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

The record makes clear what the completed study was intended to examine: whether an investigational weight-bearing cone-beam CT scan could provide ankle-stability measurements for supination-external rotation ankle fractures in comparison with gravity stress X-ray. It also identifies medial clear space distance on weight-bearing CBCT as the primary outcome and gives the unit, summary type, and timeframe. These details help define the study question, but they are not outcome findings.

The posted results do not include a numerical primary endpoint value, standard deviation, comparison estimate, confidence interval, or p-value. The two listed secondary imaging outcomes also have no numerical results in the registry record. Consequently, readers cannot determine from this record the observed measurement levels, how much measurements varied, or whether the imaging methods produced similar or different results.

In general, a measurement study can inform how a measurement method behaves in a particular setting when it reports estimates and their uncertainty, along with sufficient design and analysis details. The record does not provide the information needed to judge the magnitude or precision of a method comparison. Nor does it report a diagnostic threshold, classification results, or other measures that would establish how well a measurement identifies instability.

The registry lists enrollment of 9 and marks the study completed. Those details do not establish that every enrolled participant contributed data to every endpoint, or that the study was sufficiently precise for its intended comparison. The registry does not report the analysis population or a trial-specific sample-size justification. The separate planning illustration should not be read as observed power or as evidence that the study achieved a particular degree of precision.

Accordingly, the record supports a description of the research question, measures, and recorded safety counts, but not a conclusion about the comparative performance of the imaging methods. It also does not establish that one measurement method is preferable, or that a particular measurement predicts clinical outcomes. Such conclusions require results and methodological details that are not reported in the registry record.

14. Why This Trial Matters Statistically

This study is statistically notable because it concerns measurement rather than a randomized comparison of treatments. The stated aim is to compare ankle-stability measures obtained with an investigational weight-bearing cone-beam CT scanner and gravity stress X-ray. In measurement research, the key statistical question is not merely whether each method produces a number, but what the relationship between measurements means for the intended use. The registry record does not report the analysis needed to answer that question.

The endpoint is a continuous distance, recorded in millimeters and summarized by a mean and standard deviation. Those summaries can describe a sample, but by themselves they do not demonstrate agreement between methods, establish a threshold for instability, or describe the precision of a comparison. General statistical interpretation depends on a clearly stated estimand, a defined measurement structure, and estimates with appropriate uncertainty. These details are not reported in the registry record.

The design description also matters. The registry identifies an “Ankle fracture cases” group, does not state allocation, and explicitly does not describe a randomized, like-for-like control comparison. The sample-size assumptions use equal allocation between two arms for a planning illustration, but those assumptions do not redefine the actual study. Distinguishing a planning calculation from a study design helps prevent an inappropriate interpretation of the record.

The enrollment of 9 makes transparent reporting of the observations and their uncertainty especially important. However, the registry record lists no analyses and no numerical outcome results. Without those, it is not possible to assess the precision of the recorded measurements or determine how much information the study contributes about differences between imaging methods. The statistical importance of the record therefore lies as much in the limits of what it reports as in the measurement question it sets out to address.

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.

Important trial-specific details are not reported in the registry record. These include eligibility criteria, participant characteristics, how instability was defined, the measurement protocol, and how readers or assessors obtained the medial clear space measurements. Without these details, the setting and reproducibility of the registered measurements cannot be fully assessed.

The primary endpoint has a stated measurement, unit, summary form, and baseline single-day timeframe, but no numerical result is reported. The registry lists two secondary imaging outcomes but does not provide their values or analyses. It also lists zero analyses, so there are no posted estimates with which to evaluate the magnitude or precision of a comparison.

The record does not state how many of the 9 enrolled participants had usable data for each endpoint, or define the population included in any analysis. Missing-data handling, exclusions, and reasons for unavailable measurements are not reported. Allocation is not stated, and the study is not described as a randomized comparison with like-for-like control arms. The record also does not explain whether the different method measurements were linked within participants or how such a relationship was handled analytically.

No detailed statistical plan, trial-specific sample-size justification, masking information, or multiplicity approach is reported in the registry record. The sample-size assumptions are described as a planning illustration and should not be taken as evidence of observed power or as a description of the study’s actual allocation. Finally, the safety record provides event counts but does not report definitions, collection procedures, or the observation period. Together, these reporting gaps limit interpretation of both the imaging comparison and the safety counts.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Computed Tomography for Evaluating Supination-external Rotation Type Ankle Fractures — NCT02599441.
• Registry record last updated 2019-10-25; status last verified 2019-10.
• Results first posted 2019-10-25.
• 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

The registry record describes a completed study sponsored by the State University of New York at Buffalo, with a start date of 2016-02 and primary completion on 2017-02-02. It lists 9 participants enrolled and concerns supination-external rotation ankle fractures.

The stated objective is to compare ankle-stability measures from an investigational weight-bearing cone-beam CT scan with gravity stress X-ray. The primary outcome is medial clear space distance in the ankle joint on weight-bearing CBCT, expressed as a mean with standard deviation in millimeters at baseline in a single-day study. Medial clear space on gravity stress X-ray and standard X-ray are listed as secondary outcomes.

The registry record lists zero analyses and does not report numerical results for the primary or secondary outcomes. It does not state allocation and does not describe a randomized, like-for-like control comparison. Safety entries list 0 serious adverse events, 0 other adverse events, and 0 deaths among the 9 at risk in the recorded group. The available record therefore describes the study question and registered measurements, but does not provide numerical evidence to assess the comparison between imaging methods.