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 Efficacy of Multimodal Periarticular Injections in Operatively Treated Ankle Fractures (NCT02967172), a randomized phase 4 study. The primary outcome is Change in Post-operative Visual Analog Pain Scores (VAS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02967172 |
| Phase | Phase 4 |
| Condition | Pain, Postoperative, Ankle Fractures |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 100 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Iowa |
| Results posted | Yes |
2. Clinical Question
Population
Patients undergoing operative treatment for closed, rotational ankle fractures. The registry record describes standard surgical care for each fracture pattern but does not report further eligibility details or a separate analysis population.
Intervention
A peri-incisional multimodal injection administered during surgery while the patient remained under general anesthesia. The record describes an injection after fixation and before skin closure; it does not provide a complete, unambiguous account of the mixture in the arm description.
Comparator
Standard ankle fracture fixation without a peri-incisional injection, alongside standard opioid analgesic regimens. The record does not describe additional details of postoperative analgesic management or whether it was identical in practice across arms.
Primary question
How did postoperative pain scores, measured on a visual analog scale, compare between the injection and control groups during the first 48 hours after surgery? The registry lists pain as the primary outcome, but it does not report the group results or a statistical comparison.
The study hypothesis was that the injection group would have lower pain scores, lower opioid requirements, shorter postoperative length of stay, and more patients discharged home. These are hypotheses, not findings. The registry lists opioid use in the first 24 hours, length of stay, and return home as secondary outcomes. It does not report results for those outcomes, either.
The primary outcome is described as mean pain scores at 24 hours and 48 hours after surgery. Although the title refers to change in pain scores, the registry does not explain a baseline measure or define how change was calculated. Readers therefore should not treat the record as establishing a change from baseline, or a difference between groups, without reported outcome estimates and analysis details.
3. Trial Design
The registry identifies NCT02967172 as a completed, randomized, double-masked, parallel-group, Phase 4 trial sponsored by the University of Iowa. It lists enrollment as 100. The recorded start is 2016-10 and the primary completion date is 2018-09-21. These details describe the registered design and status; they do not supply outcome results.
The comparison was between peri-incisional injection and control. In the injection arm, the registry describes a single multimodal injection after fracture fixation and before skin closure while the patient remained under general anesthesia. The control arm was described as receiving standard fixation without a peri-incisional injection. The study summary says both groups were to receive standard opioid analgesic regimens. The complete injection-arm description is truncated, so its full administration details are not reported in the registry record.
Double masking indicates that the study was registered as masked, but the registry record does not identify which groups of people were masked or explain how masking was maintained. Details such as allocation concealment, the randomization procedure, and whether masking could be assessed are not reported in the registry record. The parallel model means the registered comparison assigned participants to an injection or control arm rather than describing a crossover comparison.
VAS pain was scheduled for assessment immediately following surgery and every 4 hours thereafter through 48 hours. The primary outcome description says scores were reported as mean values at 24 hours and 48 hours. Secondary outcomes were opioid use in the first 24 hours after surgery, postoperative length of stay, and return home following surgery. The registry lists five outcome measures, but supplies no results for these outcomes. It lists no analyses.
The record does not report the protocol’s sample-size justification, detailed statistical analysis plan, handling of protocol deviations, or an interim analysis plan. None should be inferred from the design label or from enrollment.
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
| Stage | Peri-incisional Injection | Control |
|---|---|---|
| STARTED | 49 | 51 |
| COMPLETED | 49 | 51 |
| NOT COMPLETED | 0 | 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 | Peri-incisional Injection | Control | Total |
|---|---|---|---|---|
| Participants analysed | 49 | 51 | 100 | |
| Age, Customized: Age range | years | 40 (20 to 80) | 41 (18 to 80) | 40 (18 to 80) |
| Sex: Female, Male: Female | Participants | 30 | 30 | 60 |
| Sex: Female, Male: Male | Participants | 19 | 21 | 40 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Age | years | 45.4 (SD 17.6) | 43.7 (SD 17.6) | 44.6 (SD 17.6) |
6. Primary Endpoint
The registry lists the primary outcome as Change in Post-operative Visual Analog Pain Scores (VAS), measured over Immediately following surgery, then every 4 hours following surgery for 48 hours post-surgery..
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | 0 to 100 score on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is postoperative pain assessed with a visual analog scale. The registry describes a 100-mm scale, expressed as a 0 to 100 score, on which 0-mm means no pain and 100-mm means the most extreme pain imaginable. Higher scores indicate worse pain. Patients reported their pain, making the outcome a patient-reported measure rather than an assessment made solely by a clinician.
The recorded assessment schedule begins immediately following surgery and continues every 4 hours through 48 hours after surgery. The outcome description specifies mean scores at 24 hours and 48 hours. Those time points represent pain at particular postoperative stages; they are not interchangeable with an overall average across the entire follow-up period. The registry does not explain whether all scheduled assessments were combined in any additional summary.
In general, pain scores can capture a symptom that is not fully represented by opioid consumption or discharge timing. Repeated measurement can describe how reported pain changes over the postoperative period, but interpretation depends on which assessments are analyzed, how missing scores are handled, and how comparisons are made. Those analysis details and the group means, measures of variability, and between-group estimates are not reported in the registry record. The word “change” in the endpoint title does not itself establish a baseline-to-follow-up calculation; the record does not define such a calculation.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies postoperative VAS pain as the primary outcome, but it does not report the pain scores for either group or a comparison between them. It therefore does not establish whether the observed pain scores differed, how large any difference was, or how precisely an effect was estimated. No conclusion about the direction or magnitude of a treatment effect can be drawn from the registered hypothesis alone.
The outcome was scheduled repeatedly, with mean scores specified at 24 hours and 48 hours. Results at each time point would need to be read in relation to their corresponding estimates and uncertainty. A difference at one time point would not automatically describe pain throughout the full 48-hour period. The registry does not report whether the planned schedule was completed, whether the listed means are based on all randomized participants, or how missing assessments were treated.
The secondary outcomes address different aspects of postoperative care. Opioid use in the first 24 hours concerns medication consumption; length of stay concerns time from operation conclusion to discharge; return home concerns discharge disposition. Their measurement and interpretation are not the same as those of the pain scale. The record gives no group-level results or analyses for these secondary outcomes, so none can be interpreted as showing a benefit or harm.
In general, an estimated group difference is more informative when paired with a confidence interval, which expresses the range of effect values reasonably compatible with the data under the analysis model. A p-value addresses compatibility with a specified null model, but by itself does not convey the size or clinical importance of an effect. The registry record reports no effect estimates, confidence intervals, or p-values for the outcomes.
Enrollment and trial completion do not substitute for outcome reporting. The registered sample-size assumptions describe a planning illustration based on an observed effect and a normal approximation, but the registry record does not state the trial’s own design justification or give the illustration’s numeric results. Such planning quantities, when available, are not observed power and are not evidence that an outcome difference was detected.
There are also no listed statistical analyses in the registry record. Without a reported analysis, it is not possible to determine whether comparisons were adjusted, how repeated pain assessments were modeled, or whether the analysis followed the randomized assignment. These absences limit what can be concluded from the record: it describes the intended questions and measurements, not the results needed to answer them.
9. Statistical Methods Explained
The registry labels the primary outcome as continuous and says that it is summarized by a mean and standard deviation. A mean describes the central level of a set of scores; a standard deviation describes how spread out individual scores are around that mean. These summaries can help characterize pain scores within a group, but they do not on their own quantify the uncertainty in a difference between groups. The registry does not report the group means or standard deviations.
What does the VAS measure?
The recorded instrument is a patient-reported visual analog scale from 0 to 100, with higher values indicating worse pain. A score is an observation on a scale, not a direct measure of opioid use or another clinical outcome. A group mean can be useful for comparing average scores, while the spread of individual scores matters because participants may report quite different experiences. The registry does not report whether the scale was administered in a particular format beyond the stated 100-mm scale, or whether scores were checked for completeness or consistency.
How should repeated scores be considered?
Pain was scheduled for assessment immediately after surgery and every 4 hours through 48 hours. Repeated observations from the same participant are generally related: a person’s scores over time are not independent measurements in the way scores from unrelated people might be. In general, an analysis of repeated measures should account for this within-person dependence, or define a particular time point or summary as the comparison of interest. The record names mean scores at 24 hours and 48 hours but does not state which statistical method was used, whether all scheduled scores entered an analysis, or whether the time points were analyzed separately.
The endpoint title uses the phrase “change in” postoperative VAS scores. A change analysis requires a defined starting value and a rule for comparing that value with later measurements. The endpoint description reports postoperative means at 24 hours and 48 hours, but does not define a baseline score or a change calculation. It is therefore important not to assume that the registered endpoint was analyzed as a change from baseline.
What do uncertainty measures tell readers?
In general, a confidence interval places an estimate in context by showing a range of values compatible with the data under the specified model and assumptions. A narrow interval indicates greater precision than a wide interval, but precision is not the same as clinical importance. A p-value addresses how compatible the data are with a null hypothesis under a particular statistical model; it does not tell readers the probability that the hypothesis is true. The registry record reports no confidence intervals, p-values, or between-group estimates for the primary endpoint.
The record states that there are no listed analyses. It consequently does not describe whether the analysis used an unadjusted comparison, an adjusted model, or another method. The statistical plan, including model selection and handling of repeated assessments, is not reported in the registry record. No method should be attributed to the trial in the absence of that information.
What is over-dispersion, in general?
Over-dispersion is a general concern when observed variability is greater than a statistical model assumes. If a model understates variability, its uncertainty estimates can be too small and its tests can appear more decisive than the data warrant. Whether over-dispersion is relevant depends on the outcome and model. The registry does not report a model for the primary outcome or diagnostics that would allow readers to assess this issue in this trial.
The record’s sample-size assumptions describe a planning illustration: a two-sided significance level of 0.05, equal allocation, a normal approximation, and an effect defined as a stated fraction of an observed effect. It also distinguishes planning quantities for participants per arm from total events for time-to-event outcomes. These are assumptions for illustration, not a reported account of the trial’s design rationale. The numeric planning results are not stated in the registry record, and planning estimates must not be interpreted as observed power.
No recalculated outcome estimates are reported in the registry record, so there is no recalculation to compare with a sponsor analysis. In general, a recalculation from summary statistics is unadjusted and can differ from a sponsor’s analysis if the latter uses a prespecified model or other information. Where a discrepancy exists, the sponsor’s own analysis takes precedence; the registry record does not provide an analysis against which to assess such a discrepancy.
10. Multiplicity, Missing Data and Analysis Populations
The primary pain outcome involves repeated scheduled assessments and names mean scores at 24 hours and 48 hours. Considering results at multiple times can raise multiplicity concerns: in general, the more comparisons made, the greater the chance of at least one apparently unusual result arising by chance when all null hypotheses hold. A prespecified primary time point, an overall repeated-measures test, or an adjustment for multiple comparisons are possible general approaches, but the registry record does not state which approach, if any, was planned or used.
The record also lists secondary outcomes: opioid use in the first 24 hours after surgery, postoperative length of stay, and return home following surgery. It does not report how these outcomes were ordered, whether they were considered confirmatory or exploratory, or whether any multiplicity procedure was applied. No analyses are listed in the registry record, so the treatment of multiple endpoints cannot be evaluated.
Missing-data handling is not reported. The registry does not state how missing VAS assessments, incomplete outcome measurements, or unavailable discharge information were handled. It does not report the number of participants with observed data for each outcome or the reasons for any missing measurements. In general, missingness can affect both the amount of information available and the interpretation of a comparison, particularly when missingness differs by group or relates to participants’ outcomes.
The analysis populations are also not described. The record does not say whether the primary analysis followed randomized assignment, included only participants who received the assigned intervention, or used another population definition. It does not report protocol deviations or exclusions from analysis. These omissions prevent assessment of how the randomized design was carried through into the outcome analysis.
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 |
|---|---|---|---|
| Peri-incisional Injection | 0 | 49 | 0.0% |
| Control | 0 | 51 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Peri-incisional Injection | 0 of 49 |
| Control | 0 of 51 |
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 |
|---|---|
| Peri-incisional Injection | 0 of 49 |
| Control | 0 of 51 |
The registry lists serious adverse event figures separately for the peri-incisional injection and control groups. For the injection group, 49 were listed as at risk and 0 as affected by a serious adverse event; for control, 51 were listed as at risk and 0 as affected. The deaths field is 0 in each group. The record also lists 0 other adverse events for the injection group, with 49 at risk, and 0 for control, with 51 at risk.
These are registry counts, not comparative estimates. With zero recorded events in both groups, the listed figures do not quantify a difference in risk or provide an uncertainty interval. They also do not establish that the groups have identical safety profiles. The record does not report the adverse-event observation window, event definitions, severity grading beyond the serious-event category, or the method used to collect events. The absence of reported events in these fields should therefore be read as a description of the registry entries, not as proof that no event could occur or that the intervention is safe.
In general, safety interpretation depends on how completely events were collected, how long participants were followed, and how events were classified. Those details are not reported in the registry record. No medical recommendation follows from these counts.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a randomized, double-masked, parallel-group trial was registered to study peri-incisional multimodal injection during operative treatment of closed, rotational ankle fractures. Its primary outcome was postoperative pain measured with a VAS, and the study also listed opioid use, length of stay, and discharge home as outcomes. The record includes the study hypothesis and descriptions of the intended comparison.
It does not report the group pain scores, an estimated between-group effect, uncertainty around an estimate, or statistical test results. It therefore cannot show whether pain scores were higher or lower in either group, how large a difference may have been, or how precisely any effect was estimated. It likewise provides no outcome results for opioid use, length of stay, or discharge home. The hypothesis that the injection group would have better results is not evidence that this occurred.
The safety fields record zero serious adverse events, zero other adverse events, and zero deaths in each group. Those entries are relevant descriptions of what the registry reports, but the record does not specify the event-collection period or provide uncertainty estimates. They cannot establish equivalence between groups or rule out uncommon harms.
In general, a trial result is best understood through the outcome definition, the comparison estimate, its uncertainty, and the analysis population. The registry record contains important design and measurement details, but its listed analyses are absent and its outcome results are not reported. Conclusions about efficacy, the size of any effect, or the precision of an estimate are therefore not supported by this record alone. These limits concern the available registry information; they are not evidence that an effect was absent.
13. Why This Trial Matters Statistically
This trial addresses an outcome that is directly reported by patients: postoperative pain after operative treatment of ankle fractures. Its design also links pain measurement with opioid use, time to discharge, and discharge disposition. Statistically, these outcomes illustrate why a study’s central question and its measurement plan matter: symptom scores, medication consumption, and discharge events capture different dimensions and require distinct interpretations.
The repeated VAS schedule makes the choice of analysis especially relevant. Scores collected from the same participant over time are related in general, and a comparison at a selected time point answers a different question from an analysis of the trajectory across follow-up. The registry names mean pain scores at 24 hours and 48 hours but does not report the analysis method or results. That gap prevents readers from seeing how the repeated measurements were translated into an estimate.
The randomized design is important because random assignment is intended to support a fair comparison between intervention groups. However, understanding the results also requires information about analysis populations, missing observations, adherence, and uncertainty. Those elements are not reported in the registry record. The registered design alone cannot show whether the intended comparison was preserved in the analysis.
The record is also a useful reminder that a registered hypothesis, completed status, and safety counts are not substitutes for outcome estimates. Readers need reported group results and analyses to judge direction, magnitude, and precision. In this case, the registry documents the clinical question and planned measures, but does not report the results needed for a statistical answer.
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 for interpreting this trial from the registry record is that outcome results are not reported. The record identifies the primary endpoint and secondary outcomes but gives no group means, between-group estimates, confidence intervals, or p-values. It lists no analyses. Consequently, the efficacy question cannot be answered from the registry entries.
The endpoint description leaves important analytical details unclear. The title refers to change in postoperative VAS scores, while the description specifies mean values at 24 hours and 48 hours. A baseline value and a definition of change are not reported. The full repeated-measures analysis, the handling of measurements at other scheduled times, and any adjustment for multiple comparisons are not reported either.
Further limitations concern conduct and reporting details. The record does not identify who was masked, explain allocation concealment, describe the randomization procedure, or state the analysis population. It does not report missing-data methods, participant flow, adherence, protocol deviations, or reasons for missing assessments. These details are necessary to assess how the registered design relates to the analyzed outcomes.
The intervention description is incomplete: the injection-arm text is truncated, and the brief summary does not give a complete, unambiguous composition. The registry also does not report the adverse-event observation period or event-collection procedures. Although it lists zero serious and other adverse events and zero deaths in each group, those counts do not resolve the missing safety details or quantify uncertainty.
The record’s planning assumptions are not a substitute for the trial’s own design justification. The sample-size rationale and analysis plan are not reported in the registry record. These limitations apply to interpretation of the registry record; they do not establish what results may be available elsewhere.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Efficacy of Multimodal Periarticular Injections in Operatively Treated Ankle Fractures — NCT02967172.
- Registry record last updated 2023-12-15; status last verified 2023-12.
- Results first posted 2023-12-15.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT02967172 is a completed, randomized, double-masked, parallel-group, Phase 4 trial sponsored by the University of Iowa. The registry lists enrollment as 100, a start of 2016-10, and primary completion on 2018-09-21. It concerns peri-incisional multimodal injection versus control during operative treatment of closed, rotational ankle fractures.
The primary outcome is postoperative VAS pain, with mean scores specified at 24 hours and 48 hours after surgery. Secondary outcomes include opioid use in the first 24 hours, postoperative length of stay, and return home following surgery. The registry lists zero serious adverse events, zero other adverse events, and zero deaths in each group.
Outcome results and statistical analyses are not reported in the registry record. The record therefore describes the study question, design, and measures but does not provide the estimates needed to assess group differences or their precision.