Saphenous Nerve Block for Foot and Ankle Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Saphenous Nerve Block for Foot and Ankle Surgery (NCT02382744), a randomized na study. The primary outcome is Block Success.

2. Clinical Question

3. Trial Design

The registry record describes a randomized, single-masked, parallel-group trial with recorded enrollment of 80. The two groups received saphenous nerve blockade using the transsartorial approach: ultrasound guidance alone, or ultrasound guidance with nerve stimulation. The registry lists 40 participants in each group for the primary outcome. Which people were masked is not reported in the registry record, nor are details of the randomization sequence or allocation concealment.

The trial is listed as completed. Its recorded start was 2015-02 and its primary completion was 2015-10. The listed phase is NA. The sponsor was the University of British Columbia. The registry summary places the study in the context of foot and ankle surgery and describes the two techniques as commonly used at St. Paul's hospital; detailed information about the study setting is not reported in the registry record.

The primary outcome was block success at 30 minutes after the nerve block, defined by complete absence of pinprick sensation at two different anatomic areas of the saphenous nerve. Secondary outcomes listed in the record address block failure, sensory blockade, onset, elicitation of a tapping sensation, stimulation current, and time required to administer the block. The registry lists 15 outcome measures, eight analyses, and 10 posted secondary outcomes. The analysis populations, participant flow after randomization, and handling of missing outcome data are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

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 Block Success, measured over 30 minutes post nerve block.

The primary endpoint is the number of participants with complete absence of sensation to pinprick at two different anatomic areas of the saphenous nerve, assessed 30 minutes after the block. This is a binary outcome: each participant either meets the stated success definition or does not. The registry expresses the result as a participant count in each group.

This endpoint provides an operational measure of sensory block success at a specified time. A defined sensory examination makes it possible to compare the two block techniques using the same criterion, rather than relying only on an overall impression of whether a block was successful. Requiring complete absence of sensation at both anatomical areas is a stringent definition as written in the registry. It does not measure every aspect of the procedure or the patient's experience.

The primary outcome should therefore be interpreted narrowly. It concerns pinprick sensation at 30 minutes, not the duration of blockade, postoperative pain, nausea or vomiting, or longer-term outcomes. Those outcomes are not the primary endpoint described in the registry record. The endpoint can indicate how often the specified sensory criterion was met in each group, but it cannot by itself establish how patients felt or whether other clinical outcomes differed.

7. Results Posted in the Registry

• Ultrasound Guidance + Nerve Stimulation: 55.0% (22/40) versus 45.0% (18/40) on control; risk difference 10.0 percentage points (95% CI -11.8 to 31.8), risk ratio 1.22 (0.79–1.90); unadjusted two-proportion z-test p = 0.371.

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.

Any Evidence of Blockade (Decreased or Complete Absence of Sensation)

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Ultrasound Guidance + Nerve Stimulation: 92.5% (37/40) versus 97.5% (39/40) on control; risk difference -5.0 percentage points (95% CI -14.5 to 4.5), risk ratio 0.95 (0.86–1.05); unadjusted two-proportion z-test p = 0.305.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Ultrasound Guidance + Nerve Stimulation and the control. The interval gives the range of effects that remain compatible with the data.

Time Required to Administer Block

• 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:
  • Ultrasound Guidance + Nerve Stimulation: mean 314.00 versus 207.00 on control; difference 107.00 (95% CI 61.66 to 152.34), standardized effect d = 1.03; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Ultrasound Guidance + Nerve Stimulation than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The listed secondary outcomes broaden the assessment beyond the primary definition of complete sensory block. They address whether there was any sensory evidence of blockade, block failure or incompleteness, onset, stimulation responses and current, and the time required to administer the block. Together, these outcomes concern both sensory response and procedural features. Their interpretation is complementary to the primary endpoint, not a substitute for it: a measure of any blockade is less stringent than complete absence of sensation at the specified sites, while procedure time concerns workflow rather than sensory success.

The secondary findings should be considered as a group of exploratory or supporting results. The registry lists 10 posted secondary outcomes and eight analyses, but does not report a multiplicity adjustment or identify a hierarchy governing interpretation across secondary outcomes. For some listed measures, numerical results are not reported in the registry record. This limits the ability to judge whether the observed pattern is consistent across all of the planned or posted measures.

Unadjusted secondary tests carry less weight when many outcomes are examined because the chance of at least one apparently notable result can increase as the number of comparisons grows. A nominal p-value for an individual outcome does not account for that wider set of questions. Secondary results can help describe how the techniques differ across related dimensions, but they should not overturn the primary analysis on their own, particularly when the analysis plan and multiplicity handling are not reported. The most defensible reading is to treat these results as context, keeping their outcome definitions and uncertainty in view rather than treating every secondary comparison as a separate confirmatory conclusion.

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

• Block Failure Rate
• Any Evidence of Blockade (Decreased or Complete Absence of Sensation)
• Incomplete Block Rate
• Speed of Onset for Nerve Block (Complete Blockade)
• Rate of Success of Elicitation of a Tapping Sensation
• Mean Minimum Stimulation Current
• Rate of Success of Elicitation of a Tapping Sensation at < 0.6 Milliampere (mA)
• Time Required to Administer Block

9. Statistical Interpretation

10. Statistical Methods Explained

What does a risk difference describe?

For a binary outcome, a risk difference compares the proportion meeting the outcome in one group with the proportion in the other. A value above zero means the outcome was more frequent in the group named first in the contrast; a value below zero means it was less frequent. The sign depends on the order of the groups. For the primary endpoint, the registry's reported estimate is 10.0 percentage points, comparing ultrasound guidance plus nerve stimulation with ultrasound guidance alone. The confidence interval spans values on either side of no difference, so its point estimate should not be read as a precise estimate of the underlying effect.

A risk difference is an absolute comparison. It keeps the result tied to the observed outcome proportions and can be read in the outcome's original percentage scale. Other measures, such as a risk ratio or odds ratio, express the comparison differently. They do not answer a fundamentally different trial question, but their numerical values and interpretation depend on the scale used. The registry's sponsor analysis reports a difference between proportions, while the accompanying recalculation also expresses the primary comparison as a risk difference.

What does the Fisher exact test contribute?

The sponsor reports Fisher's exact test for the primary comparison. This test evaluates how compatible the observed group counts are with a null comparison under its test assumptions. Its p-value is not the probability that the null hypothesis is true, nor does it quantify the probability that the observed difference arose by chance in an everyday sense. It summarizes how unusual data at least as discrepant as those observed would be under the null model. The sponsor's reported p-value is 0.25. A p-value does not convey the range of effect sizes compatible with the data, so it is best read alongside the estimated difference and its confidence interval.

The recalculated p-value is unadjusted and comes from a simple recalculation using the posted summary statistics. The registry's analysis and the recalculation need not have identical p-values because the methods can differ. The sponsor's analysis remains the trial's own reported analysis; the recalculation is a separate statistical aid and does not replace it.

How should the mean difference be read?

Procedure time is reported as a mean in seconds with a standard deviation for each group. The standard deviation describes spread among observed participant times; it is not the uncertainty around the group mean. The estimated mean difference of 107 s compares the group means, with the group using ultrasound guidance plus nerve stimulation contrasted against ultrasound guidance alone. A positive estimate in that order indicates a higher mean time in the first-named group.

The reported two-sided t-test assesses compatibility with a null mean difference in either direction. Its p-value is < 0.001. The recalculated unadjusted p-value is < 0.001. These threshold reports should be retained as written; they are not exact p-values. The confidence interval for the mean difference supplies a range of estimates compatible with the data under the interval method. It also gives a sense of precision in the seconds scale, which a p-value alone cannot provide.

Why do dispersion and design matter?

In general, variability among participant measurements affects how precisely a group mean and its difference can be estimated. Greater spread can make a mean difference less precise when other aspects of a study are held constant. The reported standard deviations show that procedure times varied within both groups. For binary outcomes, the number of participants meeting the criterion and the number assessed contribute to the precision of an estimated proportion and its difference.

Random assignment is intended to make treatment groups comparable on average, but it does not guarantee that every relevant characteristic is balanced in a particular trial. The registry record identifies the trial as randomized but does not report the sequence-generation or concealment procedures. It describes the study as single-masked but does not say who was masked. The registry also does not report an adjusted model for the outcomes, so the presented comparisons should be treated as unadjusted unless the sponsor's report specifies otherwise.

Confidence intervals, p-values, and effect estimates answer related but different questions. The effect estimate describes the observed contrast, the interval conveys uncertainty about its magnitude, and the p-value assesses compatibility with a specified null hypothesis under a test procedure. General statistical interpretation is strongest when all three are considered together, while keeping the endpoint and analysis method in view.

11. Confidence Intervals and Precision

The primary sponsor estimate is a difference between proportions of 10.0 percentage points, with a 95% confidence interval from -11.9 to 31.9. The interval includes zero and extends to both negative and positive values. Thus the observed estimate favors the group receiving nerve stimulation, but the interval also includes no difference and estimates favoring ultrasound guidance alone. Its breadth indicates that the primary comparison is not estimated with high precision. The p-value of 0.25 is consistent with that uncertainty; it does not prove equivalence or show that the techniques have identical success rates.

The recalculated primary interval, from -0.118 to 0.318 on the risk-difference scale, also spans zero. It is a simple unadjusted recalculation from the posted counts. The sponsor's reported interval is the trial's own analysis and should be distinguished from the recalculated interval. The registry does not report an equivalence or non-inferiority margin, so the interval cannot be used to conclude that the techniques are equivalent.

For procedure time, the sponsor reports a mean difference of 107 s and a 95% confidence interval from 61 to 153 s. That interval lies above zero, with values indicating a longer mean administration time for the group using nerve stimulation under the stated contrast. The recalculated interval, from 61.66 to 152.3 s, is close to the sponsor's reported interval. Precision is better described by the interval's range than by the p-value alone; the interval still allows a range of possible mean differences.

In general, a confidence interval is a range generated by a method designed to capture the underlying parameter at a stated frequency across repeated studies under its assumptions. It is not a range containing a stated percentage of individual participant outcomes, and it is not a probability statement about this particular fixed parameter after the data have been observed.

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 for the binary outcomes and the reported continuous outcome; they are not total participants across both arms. The time-to-event convention, if such a planning display is used, is to report total events, but the planning figures for these outcomes are per arm. The values illustrate the participant requirements for specified effect sizes under stated assumptions; they do not describe the enrollment or outcomes observed in this completed trial.

The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to the stated fraction of the observed effect. The registry's own original sample-size assumptions are not reported in the registry record, so these illustrations should not be treated as the trial's design justification.

The 80% power column gives the planning number of participants per arm for a design with an 80% chance of detecting the specified effect under those assumptions, if that effect is the true one. The 90% power column describes the corresponding planning target for a 90% chance. These are prospective design concepts, not guarantees that a future study will reach a particular conclusion. The calculations use the observed effect as their starting point, which is an uncertain estimate and may not represent the effect a future study should expect.

Planning for 75% or 50% of the observed effect means targeting a smaller difference than the observed estimate. Smaller effects are harder to distinguish from random variation, so they require more participants per arm under otherwise unchanged assumptions. The curve expresses this general relationship between assumed effect size and required sample size. These calculations are not observed power.

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, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.450; treatment proportion p₁ = 0.550; average p̄ = 0.500.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.7071 = 1.3859.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.7036 = 0.5921.
4. n = (1.3859 + 0.5921)² / (0.1000)² = 391.3, rounded up to 392 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
p0 <- 0.45                          # control proportion
p1 <- 0.55                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^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 (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(2382744)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 392 (80% power), 524 (90% power)
 75% of observed effect: n per arm = 697 (80% power), 932 (90% power)
 50% of observed effect: n per arm = 1,565 (80% power), 2,095 (90% power)
power.prop.test: 391.3 
Simulated power at n = 392 per arm: 0.799 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-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. Analyses Reported by the Sponsor

The registry's own primary analysis uses Fisher's exact test and reports a difference between proportions of 10.0 percentage points, with a 95% confidence interval from -11.9 to 31.9 and p = 0.25. The simple recalculation based on the posted arm counts gives a risk difference of 0.1, an interval from -0.118 to 0.318, and p = 0.371. The estimates and intervals describe the same direction and broadly similar uncertainty on their respective scales, while the p-values differ because the recalculation is not the sponsor's Fisher exact analysis.

For procedure time, the sponsor reports a mean difference of 107 s, a 95% confidence interval from 61 to 153, and p < 0.001 using a two-sided t-test. The unadjusted recalculation gives a mean difference of 107.0, an interval from 61.66 to 152.3, and p < 0.001. The small differences in the interval endpoints and p-value reflect the distinct reporting or calculation details; the registry does not flag a discrepancy.

The sponsor's analysis is the trial's reported analysis. Recalculations are useful as a check based on the posted summary statistics, but they do not replace the sponsor's method or add adjustment for factors not in the summary data. Neither analysis should be interpreted without its endpoint, estimate, and uncertainty interval.

15. Multiplicity, Missing Data and Analysis Populations

The registry lists 15 outcome measures, eight analyses, and 10 posted secondary outcomes. The available record does not report whether the investigators used a prespecified hierarchy among outcomes, adjusted for multiple comparisons, or treated secondary analyses as exploratory. It also does not report whether interim analyses were planned or conducted. Those details are not reported in the registry record and should not be inferred from the number of results listed.

Multiplicity matters because examining several outcomes or analyses creates multiple opportunities for a result to appear noteworthy by chance, even if each individual test uses a conventional threshold. An adjustment or a prespecified testing sequence can address that issue, but no such approach is described in the registry record. The reported secondary p-values should therefore be read as unadjusted unless the sponsor's result explicitly says otherwise; the record does not establish a family-wise interpretation across the outcomes.

The registry identifies a randomized, single-masked, parallel-group design, but it does not state who was masked, how the random sequence was generated, or how allocation was concealed. The primary outcome's timing and definition are reported, but the protocol, statistical analysis plan, and original sample-size justification are not reported in the registry record.

Missing-data handling and analysis populations are also not reported. The record does not state whether all randomized participants were included in each analysis, whether any participants lacked endpoint assessments, or how such cases were handled. Without those details, the posted denominators describe the reported outcome data but do not establish the analysis strategy for every randomized participant. These omissions constrain assessment of selective reporting, robustness, and the role of missing observations; they do not by themselves demonstrate that a particular bias occurred.

16. Safety Results

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

Other (non-serious) adverse events

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

Most frequent non-serious adverse event terms

For serious adverse events, the registry reports zero affected participants among 40 at risk in the ultrasound-guidance group and zero among 40 at risk in the ultrasound-guidance-plus-nerve-stimulation group. The record lists no top serious adverse-event terms. It reports other adverse events affecting 3 participants among 40 at risk in the ultrasound-guidance group and 2 among 40 at risk in the group receiving nerve stimulation.

These counts describe the adverse-event entries in the registry record; they do not establish that no unrecorded events occurred or that the techniques have identical safety profiles. The record does not provide event types for the other adverse events in the information available, and deaths are not reported in the registry record. The counts should be read as descriptive observations for this trial rather than as a precise comparison of uncommon harms.

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

The primary result describes how often the registry's specified sensory criterion was met at 30 minutes. The observed count was higher in the group receiving ultrasound guidance with nerve stimulation, but the estimated difference is uncertain: the sponsor's confidence interval includes no difference and extends to values favoring either group. The evidence therefore does not establish a precise advantage for either technique on this endpoint, nor does it establish equivalence.

The procedure-time result addresses a different question. The reported mean was higher when nerve stimulation was added, and the estimated mean difference interval lies above zero. This is evidence about the duration of block administration in the recorded trial, not about the overall value of either technique. It should not be converted into a claim about postoperative pain, nausea, vomiting, patient satisfaction, or recovery, because those are not the primary outcomes.

The comparison is limited to the studied saphenous nerve block techniques and the registry's outcome definitions. It does not compare a nerve block with no block, and it cannot establish outcomes that were not measured or reported. The posted counts and estimates are observations from this completed trial; they do not guarantee the same results in other settings or participants.

Statistical evidence is best expressed in terms of the size and precision of the observed contrasts. A p-value alone is not a measure of clinical importance, and a confidence interval is not proof that every value within it is equally plausible in practice. The registry does not give a threshold for what would count as a clinically important difference. As a result, the results can inform understanding of the measured differences and their uncertainty, but they do not by themselves settle whether either technique should be chosen in clinical care.

18. Why This Trial Matters Statistically

This trial illustrates why a comparison should distinguish the endpoint being measured from the broader clinical question that motivated the study. The primary outcome uses a specific sensory definition at a specified time, while other relevant considerations include whether any blockade was evident and how long the block took to administer. A single success count cannot represent all of these dimensions.

It also shows why effect estimates and intervals are more informative than a binary reading of a p-value. The primary point estimate favors the group using nerve stimulation, yet its interval spans no difference and effects in either direction. Reading only the point estimate would overstate certainty; reading only the p-value would conceal the range of effect sizes compatible with the data. The procedure-time result supplies a separate example in which the estimated difference and its interval are expressed in the original time scale.

Finally, the record makes the distinction between trial results and design planning important. Planning illustrations based on observed effects can show how sample-size requirements change when the target effect is smaller, but they do not reveal the original design rationale or the trial's achieved power. The original assumptions are not reported in the registry record. Keeping that distinction clear helps prevent a retrospective planning calculation from being mistaken for a justification of the completed trial or a measure of how persuasive its findings are.

19. 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 primary estimate is based on the registry's binary success definition at 30 minutes, so it does not capture block duration, later sensory changes, or patient-centered outcomes. The registry summary mentions pain control and nausea and vomiting as context, but these are not the primary endpoint described in the record. The primary confidence interval is broad enough to leave substantial uncertainty about the size and direction of the difference.

Some design details needed to assess internal validity are not reported in the registry record. These include who was masked, the randomization and concealment procedures, participant flow, analysis populations, and handling of missing outcomes. The record also does not report the original sample-size justification, the protocol, the statistical analysis plan, or the handling of multiplicity. Their absence limits independent assessment but does not show that the procedures were inadequate.

The registry focuses on a particular saphenous nerve block approach for foot and ankle surgery. Participant demographics, detailed eligibility criteria, and information needed to judge how closely the study setting matches other clinical contexts are not reported in the registry record. The findings therefore should not be generalized automatically to other nerve blocks, techniques, or populations.

Secondary outcome reporting is incomplete for some of the measures listed, and the record does not describe a multiplicity strategy. Safety counts are descriptive, with no reported serious events in either group, but the record gives limited detail about event types and deaths are not reported. These limitations make the posted results useful for understanding the measured comparisons while leaving uncertainty about their broader applicability and completeness.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Saphenous Nerve Block for Foot and Ankle Surgery — NCT02382744.
• Registry record last updated 2018-04-02; status last verified 2017-09.
• Results first posted 2018-04-02.
• 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.

23. Record Summary

NCT02382744 is a completed randomized, single-masked, parallel-group trial sponsored by the University of British Columbia, with recorded enrollment of 80. It compared saphenous nerve block using ultrasound guidance alone with ultrasound guidance plus nerve stimulation for foot and ankle surgery.

The primary endpoint was complete absence of pinprick sensation at two different anatomic areas of the saphenous nerve at 30 minutes. The sponsor reported a difference between proportions of 10.0 percentage points, with a 95% confidence interval from -11.9 to 31.9 and p = 0.25. Procedure time was also reported, with a sponsor-estimated mean difference of 107 s and a 95% confidence interval from 61 to 153 s.

The primary comparison remains imprecise, while the procedure-time estimate indicates a higher mean time in the group using nerve stimulation. Important details about analysis populations, missing data, multiplicity, and the original design assumptions are not reported in the registry record.