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 Femoral/Sciatic Block for Knee Surgery (NCT02882152), a randomized na study. The primary outcome is Analgesic Efficacy.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02882152 |
| Phase | NA |
| Condition | Knee Injuries |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 40 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Sao Paulo General Hospital |
| Results posted | Yes |
2. Clinical Question
Population
The registry record concerns people undergoing total knee arthroplasty. The condition is listed as Knee Injuries, but eligibility criteria and further details about the study population are not reported in the registry record. The record gives an enrollment of 40; additional characteristics of participants are not reported in the registry record.
Intervention
One group received femoral nerve blockade followed by catheter placement for continuous infusion, together with a single-shot sciatic nerve block. The registry lists postoperative analgesia as the study focus. Details of the continuous infusion regimen, the timing of the blocks, and other aspects of care are not reported in the registry record.
Comparator
The comparison group received intrathecal morphine. The record does not report further details about the morphine regimen or about other pain-management care received by either group. The trial is described as randomized, parallel, and unmasked.
Primary question
The primary outcome, titled Analgesic Efficacy, was pain measured with the verbal numeric rating scale at baseline, described as discharge from the post-anesthesia care unit, and at 24, 48, and 72 hours. The clinical question is whether the recorded pain scores differed between the two analgesic approaches across those assessment times. The registry record does not provide numerical group results or a single comparison that answers this question.
3. Trial Design
This completed trial is registered as NCT02882152, with the title “Femoral/Sciatic Block for Knee Surgery.” Its official title describes a comparison of continuous femoral nerve blockade plus a single-shot sciatic nerve block with intrathecal morphine for total knee arthroplasty. The sponsor is University of Sao Paulo General Hospital. The record lists a start date of 2011-08 and a primary completion date of 2014-09.
The design is randomized, parallel, and unmasked. Randomization means assignment was intended to occur by chance, but the method used to generate the sequence and the process used to conceal assignments are not reported in the registry record. “Unmasked” indicates that masking is listed as none; who knew each participant’s assignment, and whether outcome assessors were masked, are not reported in the registry record.
Enrollment is recorded as 40. The registry describes the two treatment approaches, but the information available does not establish how many participants were randomized to each group, received the assigned approach, or contributed data at each assessment time. Group-specific outcome counts are not reported in the registry record.
The primary outcome is pain on a verbal numeric rating scale, with measurements at baseline and at 24, 48, and 72 hours. Postoperative bleeding is listed as a secondary outcome. The record identifies two outcome measures and two analyses, but does not provide the analysis methods or numerical results for the primary outcome. Details such as eligibility criteria, study location, allocation ratio, adherence, follow-up completeness, and protocol deviations are not reported in the registry record. The record does not report a phase beyond the listing “NA.”
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 | Femoral Blockade | Morphine |
|---|---|---|
| STARTED | 20 | 20 |
| COMPLETED | 19 | 20 |
| NOT COMPLETED | 1 | 0 |
Reasons for not completing this period:
| Reason | Femoral Blockade | Morphine |
|---|---|---|
| Lost to Follow-up | 1 | 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 | Femoral Blockade | Morphine | Total |
|---|---|---|---|---|
| Participants analysed | 19 | 20 | 39 | |
| Age, Continuous | years | 67.3 (SD 8.3) | 58.3 (SD 10.5) | 62.5 (SD 10.3) |
| Gender: Female | Participants | 16 | 14 | 30 |
| Gender: Male | Participants | 3 | 6 | 9 |
| Weight | kg | 70.7 (SD 20.0) | 77.5 (SD 16.9) | 76.6 (SD 14.3) |
6. Primary Endpoint
The registry lists the primary outcome as Analgesic Efficacy, measured over baseline (zero hour: discharge of post-anesthesia care unit-PACU), 24hs, 48hs, 72 hours.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | units on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is titled Analgesic Efficacy and measures pain using the verbal numeric rating scale (VNRS). The registry describes an 11-point scale running from zero to 10, where zero means no pain and 10 means unbearable pain. Scores 1–3 are described as mild pain, 4–5 as moderate pain, and 7–9 as severe pain; the description does not assign a category to score 6. The endpoint is specified as a mean, with standard deviation as the dispersion measure.
Pain is assessed at baseline—defined in the record as discharge from the post-anesthesia care unit—and at 24, 48, and 72 hours. Repeated assessment can describe the course of reported pain over the postoperative period rather than relying on one measurement alone. A mean can summarize the group’s average score, while a standard deviation describes how spread out individual scores are around that average. These summaries do not show the full distribution or how each participant’s score changed.
The registry record does not report the group means, standard deviations, or a numerical comparison at any assessment time. It also does not identify a single time point as the primary comparison or define a clinically important difference.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes that the trial was designed to compare two analgesic approaches in total knee arthroplasty, but it does not provide numerical results for its primary pain outcome. In particular, it does not report group means or standard deviations at baseline, 24 hours, 48 hours, or 72 hours. It also does not provide an estimated between-group effect, a confidence interval, or a p-value for pain. Therefore, the direction, magnitude, and precision of any difference in pain scores cannot be assessed from the recorded information.
The primary outcome is measured repeatedly, and the record indicates more than one assessment time. A result at one time would not by itself describe the full pattern across follow-up. Interpretation would require clarity about which time points were compared, how repeated measurements were handled, and whether the reported comparison was adjusted for baseline or other factors. Those analysis details are not reported in the registry record. The record explicitly indicates that the primary outcome has several categories or time points and is not reduced to one comparison.
Although the registry identifies postoperative bleeding as a secondary outcome, it does not give numerical bleeding results or define how bleeding was measured in the information available. The adverse-event figures separately list zero serious events and zero other events among the participants at risk in each group. Those counts describe the recorded adverse-event entries; they do not replace results for the primary pain endpoint or establish that the groups had equivalent safety.
Without outcome estimates and their uncertainty, there is no basis in the registry record for judging whether an observed difference would be small or large, precise or imprecise, or compatible with a range of possible effects. A missing numerical result should not be interpreted as evidence that the treatments had the same effect, nor as evidence that one approach was better. The registry information supports describing the design and intended measurements, but not a conclusion about comparative analgesic efficacy.
Planning calculations based on an observed effect, when reported, are not substitutes for trial results or evidence that a study had adequate power. The record’s stated planning assumptions describe an illustration using a two-sided significance level of 0.05, equal allocation, and a normal approximation. No calculated planning values or numerical observed effect are reported in the registry record used for this interpretation.
9. Statistical Methods Explained
The registry describes a continuous outcome summarized by a mean and standard deviation. Those are familiar summaries for numeric measurements such as a pain score. The mean represents the average score in a group; the standard deviation describes the dispersion of scores around that average. Neither summary alone explains the shape of the score distribution or identifies how many participants experienced a particular level of pain.
What does a confidence interval describe?
In general, a confidence interval expresses uncertainty around an estimated effect. A narrow interval indicates greater precision than a wide interval, while the values it contains indicate which effect sizes remain compatible with the analysis and data under the method used. A confidence interval does not show the probability that a particular treatment effect is true. The registry record does not report a confidence interval for the primary outcome, so the precision of a treatment comparison cannot be assessed.
What would a between-group estimate mean?
In general, an unadjusted comparison of group means describes the observed difference in average scores without accounting for other variables. An adjusted estimate may account for baseline scores or other factors, depending on the prespecified model. These approaches answer related but not necessarily identical questions. The registry record does not report a primary-outcome estimate, an adjustment strategy, or a model, so it is not possible to identify which method was used or to reproduce a comparison.
Why do repeated measurements need attention?
Pain measurements at baseline and at 24, 48, and 72 hours are repeated observations over time. In general, scores from the same participant may be correlated: a person’s score at one assessment can be related to that person’s score at another. An analysis that treats all repeated observations as independent may misstate uncertainty. Methods for repeated measures can account for that dependence, but the appropriate method depends on the analysis question and data structure. The model, handling of within-participant correlation, and approach to incomplete follow-up are not reported in the registry record.
There is also a distinction between comparing groups separately at each assessment and estimating a group difference over time. Separate comparisons can produce multiple results, while a repeated-measures model can estimate an overall pattern or a time-specific effect. The record does not identify which of these approaches was used. It notes that the primary outcome has several categories or time points and is not reduced to one comparison. Consequently, the record does not support a single summary statement about the primary endpoint.
How should significance testing be read?
In general, a p-value describes how unusual data at least as incompatible with a specified null hypothesis would be under the assumptions of a statistical model. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of an effect. A p-value also does not communicate precision as directly as an effect estimate with a confidence interval. No primary-outcome p-value or test specification is reported in the registry record.
The record states a two-sided significance level of 0.05 among assumptions for planning illustrations. That is a planning convention and should not be mistaken for a reported trial result or for evidence that a particular test was used. The analysis plan, including any interim analyses, is not reported in the registry record.
What do the planning assumptions represent?
The record describes planning illustrations based on an observed effect, using equal allocation between arms and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. Such calculations can illustrate the participants per arm associated with a chosen planning target under the stated assumptions; they do not describe the number actually enrolled or analyzed. They are not observed power, and they do not establish that the trial’s original sample size was justified by those calculations. The trial’s own sample-size justification and design assumptions are not reported in the registry record.
For continuous outcomes, general planning calculations rely on assumptions about the effect size and variability, as well as the statistical test and allocation. If variability is poorly estimated or the analysis differs from the planning model, the illustration may not reflect the conditions of the trial. The numerical planning outputs and the numerical observed effect are not reported in the registry record used here, so no planning target can be interpreted as an achieved result.
Finally, the VNRS is bounded and uses discrete integer scores, while the endpoint is described through means and standard deviations. In general, those summaries can be useful, but examining the distribution and the chosen analysis assumptions is important, especially with limited data. Distributional checks, handling of unusual values, and sensitivity analyses are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The primary pain outcome is assessed at baseline, 24 hours, 48 hours, and 72 hours. Multiple assessment times create a multiplicity question: if separate tests are performed at each time, the chance of at least one nominally significant result can increase. In general, researchers may address this by specifying one primary time point, defining a combined longitudinal analysis, or adjusting for multiple comparisons. The registry record does not report which strategy was planned or used, and it does not identify a single primary time point. It explicitly notes that the primary outcome has several categories or time points and is not reduced to one comparison.
Postoperative bleeding is listed as a secondary outcome. The registry identifies two outcome measures and two analyses, but the definitions, hypotheses, and relationship between the outcomes and analyses are not reported in the registry record. It is therefore not possible to determine how the analyses were prioritized or whether multiplicity across outcomes was considered.
Missing-data handling is also not reported in the registry record. The available information does not state how many participants contributed data at each pain assessment, whether anyone withdrew or missed assessments, or whether an analysis used all available observations or a restricted analysis population. These details matter because incomplete follow-up can affect both the estimated group means and their uncertainty, particularly when missingness is related to pain or treatment experience.
The registry record does not define an intention-to-treat population, a per-protocol population, or another analysis population for the primary endpoint. It also does not describe deviations from assigned treatment or how such deviations were handled. Without these details and numerical results, the completeness and robustness of the primary-outcome analysis cannot be evaluated.
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 |
|---|---|---|---|
| Femoral Blockade | 0 | 19 | 0.0% |
| Morphine | 0 | 20 | 0.0% |
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 |
|---|---|
| Femoral Blockade | 0 of 19 |
| Morphine | 0 of 20 |
The adverse-event record lists zero serious adverse events among 19 participants at risk in the Femoral Blockade group, and zero among 20 participants at risk in the Morphine group. It also lists zero other adverse events among 19 participants at risk in the Femoral Blockade group and zero among 20 participants at risk in the Morphine group. These are the registry’s recorded counts for the categories shown.
Zero recorded events does not establish that the treatments have identical safety profiles or that an event could not occur. In general, event counts provide limited information when events are uncommon, follow-up is limited, or ascertainment is incomplete. The duration and method of adverse-event monitoring are not reported in the registry record. The figures also do not describe postoperative bleeding results; although bleeding is listed as a secondary outcome, numerical bleeding results are not reported in the registry record.
Deaths are not recorded as zero: the death entries are null. Accordingly, the number of deaths is not reported in the registry record. The adverse-event counts should be read as recorded safety data, not as a complete demonstration of safety or as a substitute for the primary pain results.
12. What the Result Does, and Does Not, Mean
The record describes a randomized, parallel comparison of femoral blockade with continuous catheter infusion and a single-shot sciatic block against intrathecal morphine for total knee arthroplasty. It specifies pain on the VNRS as the primary endpoint and identifies baseline, 24-hour, 48-hour, and 72-hour assessments. This information establishes what the investigators intended to compare and when pain was to be measured.
It does not establish which approach produced lower pain scores, whether any difference was statistically distinguishable from chance under a specified model, or how precise an estimated difference might be. Numerical primary-outcome results, effect estimates, confidence intervals, and p-values are not reported in the registry record. The absence of these results cannot be treated as evidence that there was no difference, that the approaches were equivalent, or that either approach was superior.
The endpoint’s scale description helps explain what a score represents, but group means alone would not reveal every feature of participants’ pain experiences. Standard deviations could describe variability around those means; they would not show the full score distribution. Because the record gives no numerical endpoint summaries, even those descriptive comparisons cannot be made. In addition, the analysis approach for the multiple assessment times is not reported, so the intended interpretation of a treatment difference across time is unclear.
The safety entries record zero serious and zero other adverse events in both groups, with the at-risk counts listed for each. These figures are limited to the recorded entries and do not demonstrate equal safety. Death entries are null, and postoperative bleeding results are not reported in the registry record. The findings therefore support a description of trial design and recorded safety counts, but not a clinical recommendation or a conclusion about comparative benefit or harm.
13. Why This Trial Matters Statistically
This trial raises several statistical issues that commonly arise in clinical comparisons. Pain is measured repeatedly after surgery, so the analysis needs to distinguish a difference at a particular time from a difference in the pattern over time. Because observations from the same person can be related, an appropriate analysis must account for that dependence or justify another approach. The registry record does not report the model used, making it impossible to assess how the repeated scores were handled.
Multiple assessment times also make the analysis question important. Separate tests at each time and one longitudinal comparison can lead to different interpretations. Prespecifying the main time point or a strategy for combining information can help clarify which result is primary and how multiplicity is managed. The record indicates that the primary outcome has several time points but does not reduce them to one comparison or describe a multiplicity strategy.
The randomized, unmasked design is also statistically relevant. Randomization is intended to reduce systematic differences in assignment, while lack of masking can influence care, participant reporting, or outcome assessment. Because pain is self-reported, knowledge of treatment assignment could be relevant to measurement. The registry record does not describe who knew assignments or whether any outcome assessment was masked.
Finally, a trial’s interpretation depends on the estimate and its uncertainty, not merely on its design or on a count of events. Here, the registry describes the pain measure and assessment schedule but does not report numerical primary-outcome results. That gap makes it important to separate the study question and design from any claim about what the comparison found. The recorded adverse-event counts provide limited descriptive safety information, not a complete comparison of risks.
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 record is that numerical results for the primary outcome are not reported in the registry record. Group means, standard deviations, treatment-effect estimates, confidence intervals, and p-values are absent. The direction, size, and precision of any difference in pain scores therefore cannot be evaluated.
The primary endpoint includes multiple assessment times, but a single primary comparison is not specified in the registry record. The statistical model, handling of repeated observations, adjustment for baseline, and any approach to multiplicity are also not reported. These omissions prevent assessment of whether the analysis matched a prespecified question and how uncertainty was calculated.
Participant flow and analysis populations are unclear. Although enrollment is recorded as 40, the record does not report how many participants were randomized, treated, followed at each assessment, or included in the primary analysis. Eligibility criteria, baseline characteristics, adherence, withdrawals, missing-data methods, and protocol deviations are not reported in the registry record. The at-risk counts in the adverse-event entries do not fill those gaps for the pain outcome.
The unmasked design may matter for a subjective pain outcome, but details about who knew assignments and how outcomes were collected are not reported. The registry also does not provide numerical results or measurement details for postoperative bleeding. These limitations concern the available registry information; they should not be mistaken for evidence that the trial did or did not conduct procedures that are not described in the record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Femoral/Sciatic Block for Knee Surgery — NCT02882152.
- Registry record last updated 2016-12-26; status last verified 2014-09.
- Results first posted 2016-12-26.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT02882152 is a completed, randomized, parallel, unmasked trial sponsored by University of Sao Paulo General Hospital. It compares femoral nerve blockade with continuous catheter infusion and a single-shot sciatic block against intrathecal morphine for total knee arthroplasty. The registry records enrollment of 40, a start date of 2011-08, and a primary completion date of 2014-09.
The primary outcome is mean pain on the VNRS, with standard deviation as the dispersion measure. Assessments are specified at baseline, defined as discharge from the post-anesthesia care unit, and at 24, 48, and 72 hours. Postoperative bleeding is listed as a secondary outcome. Numerical primary-outcome and bleeding results, analysis details, missing-data methods, and the analysis population are not reported in the registry record.
The adverse-event entries show zero serious and zero other events in the listed at-risk groups. Death entries are null, not reported as zero. These safety counts do not establish equivalence or resolve the unanswered primary-outcome question.