Liposomal Bupivacaine Versus Standard Bupivacaine in the Adductor Canal for Total Knee Arthroplasty: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Liposomal Bupivacaine Versus Standard Bupivacaine in the Adductor Canal for Total Knee Arthroplasty (NCT03182933), a randomized phase 4 study. The primary outcome is 10 Meter Walk Test.

2. Clinical Question

The trial also listed pain scores, opioid consumption in morphine equivalents, nausea, and quadriceps strength as secondary outcomes. Numerical results are posted for quadriceps strength; numerical results for the other listed secondary outcomes are not reported in the registry record.

3. Trial Design

NCT03182933, titled Liposomal Bupivacaine Versus Standard Bupivacaine in the Adductor Canal for Total Knee Arthroplasty, was a phase 4 randomized, triple-masked, parallel-group trial sponsored by the University of Wisconsin, Madison. Its official title describes an evaluation of the impact of liposomal bupivacaine injected for adductor canal block on recovery profile and block characteristics following total knee arthroplasty.

The registry lists enrollment of 64. The primary outcome results include 31 participants in the liposomal bupivacaine group and 32 in the standard bupivacaine group. The registry record does not explain the difference between the enrollment figure and the group counts in the posted primary outcome results, nor does it describe how participants without an outcome value were handled.

The study started on 2017-05-30, and primary completion was recorded as 2018-07-16. Its status is terminated. The reason for termination and the timing or circumstances of that decision are not reported in the registry record. The record identifies the condition as pain and describes a study evaluating physical therapy measures, pain scores, and opiate consumption.

The named interventions include peripheral nerve blockade, a 10 meter walk test on post-operative day 1, an in-person and telephone questionnaire, and force transduction of quadriceps strength. The primary outcome is specified at 24 hours. The registry record does not provide a fuller account of the procedures, the masking implementation, or the conduct of follow-up. It also does not report the trial's original sample-size justification or the statistical analysis plan.

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: Study aimed to obtain 70 patients to account for dropout, however was sufficiently powered if 60 patients enrolled. Study was terminated after 64th patient due to surgeon preferences.

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 10 Meter Walk Test, measured over 24 hours.

The primary endpoint was the 10 Meter Walk Test, recorded in seconds at 24 hours. It measures the time to comfortably walk 10 meters, with physical therapy judging whether the walk was safe. A time-based measure provides a direct quantitative description of performance on this particular mobility task. It is distinct from a pain score or a strength measurement: it captures the time taken to complete a specified walk rather than a participant's rating of pain or measured force.

Walking performance is relevant to recovery after total knee arthroplasty because the trial was designed to evaluate physical therapy measures as well as pain and opioid consumption. The endpoint therefore gives a functional measure that can be compared between the two randomized groups. The recorded mean was 17.1 seconds in the liposomal group and 13.4 seconds in the standard group. The estimated difference is expressed as liposomal minus standard, so a positive estimate corresponds to a longer average walking time in the liposomal group.

The endpoint is limited to the task, assessment time, and safety judgment described in the registry record. It does not, by itself, measure all aspects of mobility, recovery, pain, or later function. The registry record does not report further details about how times were collected, whether repeated measurements were taken, or how unavailable measurements were treated.

7. Results Posted in the Registry

• Liposomal Bupivacaine Group: mean 17.10 versus 13.40 on control; difference 3.70 (95% CI 0.09 to 7.31), standardized effect d = 0.51; z-test p = 0.045.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Quadriceps Strength

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Liposomal Bupivacaine Group: mean 16.50 versus 19.20 on control; difference -2.70 (95% CI -8.59 to 3.19), standardized effect d = -0.23; z-test p = 0.369.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Liposomal Bupivacaine Group and the control. The interval gives the range of effects that remain compatible with the data.

The trial's secondary outcomes broaden the question beyond the primary walking-time measure. The registry lists pain scores, opioid consumption in morphine equivalents, nausea, and quadriceps strength. These outcomes relate to different dimensions of recovery: symptom burden, medication use, an adverse experience, and physical strength. They are not interchangeable with the primary timed walk, and agreement across them would provide a more complete picture than any single measure alone.

Numerical results are posted for quadriceps strength, but numerical results for pain scores, opioid consumption, and nausea are not reported in the registry record. The available secondary outcome evidence is therefore incomplete for assessing the full set of stated recovery questions. The posted strength comparison is an unadjusted result and has an interval that includes values on both sides of zero. It does not establish that the groups had identical strength, nor does it establish a clear difference.

Secondary results generally carry less weight when many outcomes are examined without a reported multiplicity plan. Each additional test creates another opportunity for a result to appear notable by chance, and unadjusted p-values do not account for that broader set of comparisons. The registry record lists no reported analyses and does not describe a hierarchy among secondary outcomes or a correction for multiple testing. Accordingly, secondary findings should be treated as exploratory descriptions rather than as independent confirmation of the primary comparison.

The primary endpoint and the secondary measures address related but distinct aspects of recovery. A difference in walking time does not, on its own, imply a corresponding difference in pain, opioid use, nausea, or measured strength. Conversely, incomplete secondary reporting prevents a balanced assessment of whether the primary pattern was accompanied by consistent changes in other outcomes. The missing numerical results should not be interpreted as showing no difference.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Pain Scores
• Opioid Consumption in Morphine Equivalents
• Number of Participants Who Experienced Nausea
• Quadriceps Strength

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous: each participant's walk is measured as a time in seconds, and the registry reports a mean and standard deviation for each group. A mean summarizes the group's average time, while a standard deviation describes how dispersed individual times are around that average. These are different kinds of summaries. A standard deviation is not a confidence interval and does not show the precision of the estimated group mean by itself.

What does the mean difference express?

The posted contrast is the liposomal-group mean minus the standard-group mean. It is 3.7 seconds. Because the subtraction order is specified, the positive sign indicates that the liposomal group had the larger recorded mean time. The comparison is in the original measurement unit, seconds, which makes its scale interpretable as a difference in walking time. It is an unadjusted recalculation from the posted summary statistics, rather than a model-based adjusted result reported in the registry record.

For a simple comparison of independent group means, a standard error describes the estimated sampling variability of the mean difference. The posted standard errors for the two group means are 1.598 and 0.919 seconds. In general, standard errors tend to be smaller when estimates are based on more observations or when the observations show less variability. They quantify uncertainty in estimated means, not the spread of individual walking times. The registry record does not report an adjusted model or additional covariates used in the comparison.

How should the confidence interval be read?

A confidence interval gives a range of values compatible with the data under a specified method and its assumptions. For the primary mean difference, the reported interval runs from 0.086 to 7.314 seconds. The interval is for the difference between group means, not for the range of individual participants' walking times. Its lower and upper limits communicate uncertainty in the estimated contrast. A confidence interval is not a guarantee that the true value lies within the observed limits, and it does not quantify the probability that any single value is correct.

The displayed interval is based on the unadjusted summary-statistic comparison. Its interpretation relies on the assumptions used by that comparison, including an appropriate representation of the group means and their uncertainty. The registry record does not report diagnostics, a detailed model specification, or an analysis plan that would permit assessment of alternative methods. The group standard deviations differ, so the way variability is handled is relevant to precision. No claim about a particular variance structure or a prespecified method can be made from the registry record.

What does the p-value say?

The unadjusted p-value for the primary contrast is 0.045. In general, a p-value evaluates how unusual results at least as incompatible with a null model as the observed data would be, if that model and the test assumptions were true. It is not the chance that the null hypothesis is true, nor is it a measure of the size or practical importance of a difference. The word unadjusted matters: the registry record does not report a correction for testing multiple outcomes or analyses. The p-value should therefore not be treated as if it accounts for all the questions examined in the trial.

A confidence interval and p-value are related summaries of uncertainty, but each conveys different information. The interval shows the range of effect sizes compatible with the data under the method, while the p-value summarizes compatibility with a particular null value. Neither replaces consideration of the actual estimate, its direction, the outcome's meaning, the trial's size, or the completeness of the reporting.

Why can over-dispersion matter?

In general, over-dispersion means that observed variation is greater than a statistical model expects. When a model understates variability, standard errors can be too small and intervals too narrow, making results appear more precise than they are. This is a general statistical consideration, not a finding about this trial. The primary endpoint is continuous and its group standard deviations are reported, but the registry record does not identify over-dispersion as a problem or provide diagnostics to evaluate it.

The use of a mean and standard deviation is a compact way to summarize continuous outcomes, but it does not reveal the full distribution of individual values. A small number of unusually long or short times can affect the mean and standard deviation. The registry record does not post participant-level measurements or distributional diagnostics, so the extent to which the summaries represent the shape of the data cannot be assessed from the reported values alone.

What does randomization contribute?

Random allocation is intended, in general, to create groups that are comparable on average apart from the assigned intervention. It supports causal comparison when allocation is implemented as planned and outcome ascertainment and analysis preserve the randomized comparison. The registry identifies the design as randomized, triple-masked, and parallel. It does not report the randomization sequence method, allocation concealment procedures, masking details, adherence, crossover, or analysis population. Those aspects should not be assumed.

The record lists 64 enrolled participants, while the primary outcome summaries use 31 and 32 participants. It does not explain this relationship or identify whether these are all randomized participants with available outcome data. It also does not report how missing measurements were handled. In general, missing outcome data can affect group comparability if their occurrence or handling is related to assignment or outcome. Without a missing-data account, the potential impact cannot be quantified.

The registry lists zero reported analyses. Therefore, the displayed contrast and associated uncertainty are best treated as unadjusted recalculations from the posted group summaries, rather than as a fully documented sponsor analysis. The registry record does not report the original statistical plan, interim analyses, analysis population, or multiplicity procedure. Any interpretation that depends on those choices would go beyond the record.

11. Confidence Intervals and Precision

The primary mean difference is 3.7 seconds, with a 95% confidence interval from 0.086 to 7.314 seconds. The interval quantifies uncertainty in the estimated difference under the unadjusted comparison method. It spans values close to zero as well as more substantial positive differences, so the exact size of the underlying group difference is not pinned down precisely by these data.

The interval is not a range containing most individual walk times. Individual times vary within each group, with standard deviations of 8.9 seconds for liposomal bupivacaine and 5.2 seconds for standard bupivacaine. The confidence interval concerns the contrast between group means; the standard deviations describe participant-level spread. Keeping these quantities distinct is important when judging precision.

The primary outcome groups include 31 and 32 participants. The registry record does not explain whether any enrolled or randomized participants lacked a recorded outcome, nor how missing data were handled. If outcome availability differed in ways related to group assignment or walking performance, the estimated difference could be affected; the available registry entries do not allow that possibility to be assessed.

The interval is associated with an unadjusted recalculation, and the registry record lists no reported analyses. It does not report a threshold for a clinically important difference. Thus the interval can be used to describe statistical uncertainty, but it cannot alone determine whether any of the compatible values would matter in practice. Greater precision would require evidence that narrows uncertainty, alongside a clear interpretation of what differences in walking time mean in the clinical setting.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They are illustrations based on the observed primary effect and use the stated assumptions: a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The figures consider detecting 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect. The trial's own original design assumptions and sample-size justification are not reported in the registry record.

For 100% of the observed effect, the illustration gives 61 participants per arm for 80% power and 81 participants per arm for 90% power. For 75% of the observed effect, it gives 108 participants per arm for 80% power and 144 participants per arm for 90% power. For 50% of the observed effect, it gives 242 participants per arm for 80% power and 324 participants per arm for 90% power.

In general, power is the probability that a planned statistical test will detect an effect of a specified size under the assumptions used, if that effect is the true one. The 80% and 90% columns represent different target probabilities of detecting the stated effect under the planning assumptions. The 90% target requires more participants per arm than the 80% target for each effect scenario. Smaller effects need more participants because they are harder to distinguish from sampling variation.

These are planning illustrations, not observed power. They do not show the probability that the completed trial's result is correct, and they are not evidence that the original trial was designed with these assumptions. The observed result and its uncertainty should be interpreted from the enrolled groups and posted outcome statistics, rather than by treating a planning calculation as a measure of the trial's success.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 3.700; pooled standard deviation σ = 7.259.
2. n = 2 × (1.96 + 0.842)² × 7.259² / 3.700² = 60.4, rounded up to 61 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 3.7                      # observed difference in means
sigma <- 7.25929590588373                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(3182933)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 61 (80% power), 81 (90% power)
 75% of observed effect: n per arm = 108 (80% power), 144 (90% power)
 50% of observed effect: n per arm = 242 (80% power), 324 (90% power)
power.t.test: 61.4 
Simulated power at n = 61 per arm: 0.796 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when several outcomes, comparisons, time points, or analyses are examined. In general, the more questions tested, the greater the possibility that at least one result will appear statistically notable even if no underlying differences exist. A prespecified hierarchy or statistical adjustment can address this issue, but neither should be assumed without documentation. The registry record does not report a multiplicity strategy, a primary-versus-secondary testing hierarchy beyond naming the primary endpoint, or an adjustment for the posted unadjusted p-values.

The primary result has an unadjusted p-value of 0.045. That value should therefore be read as applying to the specific comparison and calculation, not as a result adjusted for the wider set of trial outcomes. Secondary outcomes include pain scores, opioid consumption in morphine equivalents, nausea, and quadriceps strength. Numerical results are posted for quadriceps strength; the other listed secondary outcome results are not reported in the registry record. The lack of numerical results does not show that those outcomes were unchanged.

The registry lists zero reported analyses. It does not provide the statistical analysis plan, identify an analysis population, describe interim analyses, or explain whether any analyses were modified after data collection began. The trial's original sample-size justification is also not reported. These omissions mean it is not possible to determine from the record whether the displayed calculations correspond to all prespecified analysis choices.

Missing-data handling is not reported. Although the record lists enrollment of 64 and gives primary outcome summaries for 31 and 32 participants, it does not explain the relationship between those figures or state whether all randomized participants were analyzed as allocated. No information is given about unavailable observations, reasons for missingness, imputation, or sensitivity analyses. In general, missingness can affect a treatment comparison if the availability of outcomes is related to group assignment or the outcomes themselves.

These gaps do not invalidate the posted descriptive statistics, but they limit what can be concluded about confirmatory inference. Without a documented multiplicity approach, analysis population, and missing-data strategy, the p-value and interval should be interpreted as unadjusted summaries with uncertainty rather than as a complete account of the trial's prespecified statistical evidence.

15. 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.

Most frequent non-serious adverse event terms

The registry reports serious adverse events for 31 participants at risk in the liposomal bupivacaine group and 32 at risk in the standard bupivacaine group. Zero participants in either group were recorded as having a serious adverse event. The registry also reports zero deaths in each group.

For other adverse events, 1 participant was affected among 31 at risk in the liposomal group, while 0 participants were affected among 32 at risk in the standard group. No serious adverse event terms are listed. These counts describe what is recorded in the registry; they do not show that no other events occurred, and the record does not provide details about event types, severity beyond the serious/non-serious distinction, timing, or attribution.

Safety counts should be interpreted alongside the size and duration of the observed trial. They are not proof that an intervention is safe or unsafe, and a count of zero does not rule out uncommon events. The registry record does not provide a fuller safety analysis or explain the terminated status, so no causal interpretation of the event pattern or termination is warranted.

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

The primary result describes a difference in average time to complete a comfortable 10 meter walk at 24 hours. The liposomal group had a mean of 17.1 seconds and the standard group had a mean of 13.4 seconds. The estimated mean difference, expressed as liposomal minus standard, was 3.7 seconds. Its 95% confidence interval was 0.086 to 7.314 seconds, and the unadjusted p-value was 0.045.

These statistics do not establish that one block is clinically preferable. The registry record does not report a threshold for a clinically important difference, and statistical evidence about an average time is not equivalent to an assessment of overall patient experience or recovery. The primary measure concerns one walking task at a specified time; it does not summarize all mobility, pain, medication use, strength, or later outcomes.

The result also does not establish that the observed difference was caused solely by the assigned bupivacaine formulation. Randomization supports a comparison in principle, but the record does not report the full analysis population, missing-data handling, adherence, or details of implementation. The comparison is an unadjusted recalculation from group summaries, and the registry lists no reported analyses. Those limitations matter when moving from a descriptive group contrast to a broad causal claim.

The trial was terminated, but the reason is not reported in the registry record. The status alone does not explain whether termination was related to recruitment, safety, logistics, or any outcome. It should not be interpreted as evidence for or against either intervention. Likewise, the small number of recorded adverse events cannot rule out events that were not observed or reported.

Overall, the posted data show a positive estimated difference in mean walking time, with uncertainty captured by the confidence interval. They do not settle the broader question of recovery after total knee arthroplasty or establish effects on the unreported numerical secondary outcomes. Interpretation should remain specific to the measured endpoint, follow-up time, and limitations of the registry record.

17. Why This Trial Matters Statistically

This trial is statistically informative because it illustrates the difference between an estimated group contrast and certainty about its size. The primary comparison is expressed in seconds, an interpretable unit, while the confidence interval makes the uncertainty visible. The estimate and interval should be considered together: a point estimate alone can give a false impression of precision, particularly when the study has relatively few outcome observations and individual measurements vary.

It also demonstrates why endpoint choice matters. A timed walking task captures a particular aspect of physical function, while pain, opioid consumption, nausea, and quadriceps strength address different aspects of recovery. A result on one endpoint cannot stand in for all the others. The registry lists several relevant outcomes, but numerical results are not reported for all of them, limiting the breadth of conclusions that can be drawn.

The trial record also highlights the importance of transparent statistical reporting. The registry identifies randomization and masking, but does not report the analysis plan, sample-size justification, missing-data strategy, analysis population, or multiplicity approach. These details help readers judge whether reported estimates follow prespecified methods and how robust they may be to analytic choices.

Finally, the planning illustrations show how assumptions about effect size and power affect participant requirements. They are useful for understanding design trade-offs, but are not evidence about the probability that the completed study detected an effect. Keeping planning calculations distinct from observed results prevents an often-misinterpreted concept, observed power, from replacing direct attention to the estimate and its uncertainty.

18. 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 registry record provides limited detail about who was eligible, participant characteristics, and the groups' comparability at baseline. It does not report the randomization sequence method, allocation concealment, or how triple masking was implemented. These design details are relevant to assessing the conduct of a randomized trial, but cannot be inferred from the design labels alone.

The record lists enrollment of 64, while primary outcome summaries include 31 and 32 participants. It does not explain whether these are the full randomized groups, whether anyone lacked an outcome measurement, or why the group counts differ. Missing-data handling and the analysis population are not reported, limiting assessment of possible bias from incomplete outcomes.

The trial status is terminated, but the reason and circumstances are not reported. The record also does not explain whether termination affected recruitment, follow-up, data collection, or analysis. The original sample-size justification, interim analyses, and detailed statistical analysis plan are not reported, so the posted planning illustrations should not be mistaken for the design rationale.

The primary endpoint reflects one comfortable 10 meter walk at 24 hours, with safety judged by physical therapy. The record does not provide further information about measurement procedures, repeated assessments, or the distribution of individual times. The posted comparison is an unadjusted recalculation, and no reported analyses are listed. A threshold for clinically important difference is not reported.

Although the registry lists several secondary outcomes, numerical results are not reported for pain scores, opioid consumption, and nausea. This leaves the broader recovery profile incompletely described. The adverse-event record is also brief, without event terms or further detail on timing and attribution. These limitations restrict interpretation to the recorded outcomes and information, rather than supporting broad conclusions about recovery or safety.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Liposomal Bupivacaine Versus Standard Bupivacaine in the Adductor Canal for Total Knee Arthroplasty — NCT03182933.
• Registry record last updated 2019-06-25; status last verified 2019-06.
• Results first posted 2019-06-25.
• 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.

22. Record Summary

NCT03182933 was a phase 4 randomized, triple-masked, parallel-group trial sponsored by the University of Wisconsin, Madison. It compared 20ml 1.33% liposomal bupivacaine with 20ml 0.5% standard bupivacaine in an adductor canal block for total knee arthroplasty. The registry lists enrollment of 64, a start date of 2017-05-30, primary completion on 2018-07-16, and status terminated.

The primary endpoint was the 10 Meter Walk Test at 24 hours. Mean times were 17.1 seconds in the liposomal group and 13.4 seconds in the standard group. The estimated mean difference was 3.7 seconds, with a 95% confidence interval from 0.086 to 7.314 and an unadjusted p-value of 0.045. Numerical results are also posted for quadriceps strength. Numerical results for pain scores, opioid consumption, and nausea are not reported in the registry record.

The registry record does not report the reason for termination, original sample-size justification, analysis plan, analysis population, missing-data handling, or multiplicity strategy.