Comparison of Femoral Tunnel and Clinical Outcome Using Two Anterior Cruciate Ligament Reconstruction Techniques: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of Femoral Tunnel and Clinical Outcome Using Two Anterior Cruciate Ligament Reconstruction Techniques (NCT02754674), a randomized na study. The primary outcome is Vascularity of Graft Tendon.

2. Clinical Question

3. Trial Design

The registry record describes a randomized, single-masked, parallel-group trial and gives the status as completed. Its official title calls it a prospective randomized trial. The two groups were Transportal and Outside in, corresponding to the reconstruction techniques in the clinical question. The intervention is classified as a procedure. The record identifies Samsung Medical Center as the sponsor.

The record lists enrollment as 67 and gives the start and primary completion as 2014-05. The brief summary describes 66 patients with anterior cruciate ligament injury, split into groups of 33 for the two techniques. These enrollment descriptions do not match the posted primary-outcome analysis counts: the vascularity results report 28 for Transportal and 26 for Outside in. Reasons for the differences, participant flow, and the number who completed follow-up are not reported in the registry record.

Single masking is recorded, but the identity of the masked parties and the procedures used to maintain masking are not reported in the registry record. The method of sequence generation, allocation concealment, and any stratification are also not reported. The record identifies the study as parallel-group but does not give further detail about the trial protocol. The trial's original sample-size justification and design assumptions are not reported in the registry record. The posted planning illustrations are calculations based on observed effects, not a record of the assumptions used to design this trial.

The primary endpoint was assessed one year after surgery. Secondary outcomes include measures at one year and two years, as well as other listed outcome types. The record lists five outcome measures and five analyses, while four secondary outcomes are named. It does not explain the relationship between those counts.

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 Vascularity of Graft Tendon, measured over 1yr after surgery.

The primary endpoint is vascularity of the graft tendon at one year after surgery. The registry describes measuring the area under the curve from a dynamic contrast-enhanced MRI signal-intensity curve. A musculoskeletal radiologist manually drew regions of interest over the intra-articular graft, including the synovial membrane, at proximal, middle, and distal zones. Image-processing software generated the signal-intensity curves and calculated the area under each curve.

The reported measure is a normalized ratio of area under the curve: the graft value was divided by the value for the medial gastrocnemius muscle. Normalization expresses the graft measurement relative to a reference tissue, rather than reporting the graft area-under-the-curve value alone. The endpoint is a quantitative imaging measure of graft vascularity; it is not itself a direct measure of knee function, stability, or patient experience.

Such a measure can be used to compare the imaging characteristics of grafts between the surgical groups at a specified follow-up time. The registry record does not explain the biological interpretation assigned to a higher or lower ratio, give a threshold for a clinically important difference, or report whether the measure was validated as a surrogate for later clinical outcomes. Consequently, the result should be read as a group comparison on the stated imaging measure, alongside rather than in place of the listed clinical outcomes.

7. Results Posted in the Registry

• Outside in: mean 4.10 versus 2.50 on control; difference 1.60 (95% CI 0.39 to 2.81), standardized effect d = 0.71; z-test p = 0.010.

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.

Instability

• 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:
  • Outside in: mean 1.90 versus 2.60 on control; difference -0.70 (95% CI -1.32 to -0.08), standardized effect d = -0.60; z-test p = 0.026.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Outside in than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Graft Maturity (SNQ)

• 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:
  • Outside in: mean 53.10 versus 69.40 on control; difference -16.30 (95% CI -32.23 to -0.37), standardized effect d = -0.54; z-test p = 0.045.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Outside in than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary outcomes cover different aspects of reconstruction, including arthroscopy grading, clinical knee scoring, instability, and graft maturity. The posted numerical secondary results include instability at two years and graft maturity measured as SNQ at one year. These measures complement the primary imaging endpoint by addressing other recorded dimensions, but they do not constitute a single combined measure of outcome.

Across the posted secondary comparisons, the recalculated results and sponsor-reported tests do not give a uniform statistical pattern. The unadjusted recalculated comparisons for instability and graft maturity have p-values below 0.05, while the sponsor reports p >0.05 for instability and p = 0.054 for graft maturity. These differences reinforce the need to distinguish the sponsor's test results from calculations based on posted summaries. They do not change what the primary endpoint measures or provide a substitute for the primary analysis.

Unadjusted secondary results carry less weight when several outcomes are examined because each additional test creates further opportunities for findings that appear notable by chance. The registry record lists multiple outcomes and analyses but does not report a multiplicity adjustment, a prespecified outcome hierarchy, or a plan for controlling the overall false-positive risk. It is therefore not possible to determine from the record whether the secondary comparisons were intended as confirmatory or exploratory.

The secondary findings should be considered as supporting context rather than as independent confirmation of the primary result. Their differing follow-up times and measurement scales also mean they cannot be read as interchangeable evidence. The registry record does not report results for all named secondary outcomes in the detail available for the posted numerical comparisons, so no broader pattern across every listed outcome can be established from the numerical summaries alone.

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

• Arthroscopy Grading
• Clinical Knee Scoring
• Instability
• Graft Maturity (SNQ)

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is a continuous measure, and the registry reports each arm's mean and standard deviation. A mean describes the central value of the measurements in a group. A standard deviation describes their spread around that group mean; it is not the uncertainty in the mean itself. The posted primary results give the Transportal mean as 2.5 with standard deviation 2.0, and the Outside in mean as 4.1 with standard deviation 2.5.

The sponsor reports a two-sided t-test for the primary comparison. In general, a two-sided test assesses evidence for a difference in either direction rather than testing only whether one prespecified group is higher. A t-test compares group means relative to the variation in the observations and the amount of information in the groups. Its p-value is calculated under a model in which the group means are equal. A small p-value indicates that data at least as different as those observed would be relatively unusual under that model, assuming the test's conditions are appropriate. It does not measure the probability that the null hypothesis is true.

The posted recalculation is an unadjusted comparison of the group means. It reports an estimated mean difference, an interval, and an unadjusted p-value. The difference is expressed as Outside in minus Transportal, so a positive estimate corresponds to a higher mean in the Outside in group. The estimate is 1.6. This direction follows from the reported means; it should not be mistaken for an adjusted treatment effect, because the record does not report an adjusted model for this outcome.

In general, an interval around a mean difference shows a range of values compatible with the data and the statistical method used, subject to the model assumptions. Its width conveys precision: a narrower interval indicates less statistical uncertainty than a wider one. An interval does not account automatically for all design or measurement limitations, and it does not say whether values within it are clinically meaningful. The registry record does not report the confidence level for the posted interval, so no confidence percentage should be assumed from the record.

The registry record states the sponsor's primary test as a two-sided t-test but does not report further test details, such as whether a pooled-variance or unequal-variance version was used. The recalculated values are described as unadjusted. Neither the original analysis plan nor the exact model specification is reported in the registry record. Interpretation therefore depends on the posted summaries and the test description, not on unreported modeling choices.

General explanation: randomization is intended to make assigned groups comparable, on average, with respect to measured and unmeasured factors at the point of assignment. It does not guarantee that the groups will be identical in a particular trial, nor does it address missing outcome data after randomization. The record says the study was randomized but does not report sequence generation, allocation concealment, or a detailed account of participant flow. Those omissions limit assessment of how randomization was implemented and how complete the reported analyses are.

General explanation: masking can reduce the risk that knowledge of group assignment influences care, assessment, or reporting, depending on who is masked and how the outcome is measured. The registry records single masking, but does not identify who was masked. The primary endpoint involves image processing and regions of interest drawn by a radiologist; the record does not state whether the radiologist or other assessors were masked to treatment assignment. The potential protection offered by masking therefore cannot be fully evaluated from the record.

The trial is listed as a parallel-group design, meaning the reported comparison is between separate groups assigned to the two techniques rather than a crossover comparison within the same participants. The record classifies the allocation as randomized. The posted outcome summaries compare the groups at their recorded follow-up times; they do not report a repeated-measures model or a model that combines outcomes across follow-up periods.

For the primary result, the sponsor reports p = 0.008, while the unadjusted recalculation reports p = 0.01. The recalculation is based on posted summary statistics and is not a substitute for the sponsor's analysis. The record marks the discrepancy indicator as false. The two reported p-values are close, but their exact difference reflects that the recalculation and sponsor analysis are not identical reported quantities. The sponsor's test is the trial analysis reported in the registry; the recalculation is useful as a transparent summary-statistic comparison.

Planning illustrations use an assumed two-sided significance level of 0.05, equal allocation, and a normal approximation. They examine effects set at stated fractions of the observed effect. General explanation: power is the chance, under a particular assumed effect and statistical model, that a planned study would reject the no-difference model at its chosen significance level. A planning calculation can show how sample requirements change under different assumed effects. It is not a measure of the probability that the observed result is correct, and it cannot reconstruct the trial's original planning without the original design assumptions.

The registry record does not report whether the trial used interim analyses, how missing observations were handled, whether analyses followed intention-to-treat principles, or whether the analysis plan was finalized before outcome data were examined. It also does not report a multiplicity procedure for the several outcomes. These are important features of a statistical analysis plan, but their absence from the record should not be filled by assumptions.

11. Confidence Intervals and Precision

The primary mean difference is 1.6, with the posted interval extending from 0.387 to 2.813. The full interval is above zero, indicating that the unadjusted estimate is compatible with a positive difference favoring a higher mean in the Outside in group, under the calculation used. The interval also includes values of different magnitudes, so the point estimate alone should not be treated as exact. The record does not report the confidence level associated with this interval.

Precision depends on the variability of measurements and the amount of information contributing to the comparison. The posted standard deviations are 2.0 for Transportal and 2.5 for Outside in, with analysis counts of 28 and 26, respectively. These summaries help describe the data but do not resolve the uncertainty about missing observations or the representativeness of the analyzed groups.

An interval is more informative than a p-value alone because it communicates both direction and a range of plausible effect sizes under the calculation's assumptions. The sponsor's reported p-value is 0.008, and the unadjusted recalculation's p-value is 0.01. Neither p-value describes the probability that the observed difference is clinically important. The registry record does not specify a clinically important difference for this normalized imaging endpoint, so the practical meaning of the interval cannot be determined from the record alone.

The estimate is a comparison of group means at the specified follow-up, not a prediction for an individual participant. The interval also does not incorporate uncertainty about how the endpoint was measured, whether missing data affected the comparison, or the consequences of considering multiple outcomes. Those issues require information not reported in the registry record.

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 planning illustrations based on the observed primary effect, with equal allocation between the arms, a two-sided significance level of 0.05, and a normal approximation. Each scenario asks what sample size would be needed if the effect to detect were the stated fraction of the observed effect. The registry record does not report the trial's original sample-size justification or original design assumptions.

The 80% power column gives the participants per arm estimated to provide an 80% chance of detecting the assumed effect at the stated significance level, if the planning assumptions and statistical model apply. The 90% power column expresses the same idea using a higher target chance of detecting that assumed effect. Neither column describes the chance that the trial's result is true, and neither is a retrospective measure of the probability that this trial detected an effect.

The entries for planning at 100% of the observed effect use the effect estimated in this trial as the assumed target. The entries for planning at 75% and 50% of the observed effect examine smaller assumed targets. Smaller effects need more participants to be detected with the same target power, which is why the illustrative requirements rise as the assumed fraction becomes smaller.

These figures are not observed power. They are hypothetical planning calculations, and the observed effect is itself uncertain. In particular, using an effect estimated from a trial as a planning target does not establish that a future study will observe that effect or that the assumptions will hold. The original trial's own planning rationale cannot be inferred from these illustrations.

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 = 1.600; pooled standard deviation σ = 2.254.
2. n = 2 × (1.96 + 0.842)² × 2.254² / 1.600² = 31.2, rounded up to 32 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 <- 1.6                      # observed difference in means
sigma <- 2.25426945355491                     # 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(2754674)
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 = 32 (80% power), 42 (90% power)
 75% of observed effect: n per arm = 56 (80% power), 75 (90% power)
 50% of observed effect: n per arm = 125 (80% power), 167 (90% power)
power.t.test: 32.2 
Simulated power at n = 32 per arm: 0.794 (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. Analyses Reported by the Sponsor

For the primary vascularity comparison, the sponsor reports a two-sided t-test with p = 0.008. The unadjusted recalculation from the posted group summaries gives a mean difference of 1.6, an interval from 0.387 to 2.813, and p = 0.01. The registry record marks the discrepancy indicator as false. The sponsor's p-value is the reported trial analysis; the recalculation is an independent unadjusted summary-statistic calculation and should be read as a check rather than as a replacement for the sponsor's result.

The two primary p-values are close and point to the same broad conclusion that the group means differ in the posted comparison. The registry does not provide the sponsor's full model specification or a confidence interval for the sponsor analysis, so the reasons for the exact difference between the two p-values cannot be identified from the record.

For secondary outcomes, the sponsor also reports two-sided t-tests. Its reported p-values do not exactly match the unadjusted recalculated p-values for the posted summaries. Such comparisons should retain the distinction between the sponsor's reported test and recalculations based on summary statistics. The registry record does not provide enough analysis detail to attribute the differences to a specific method choice.

15. Multiplicity, Missing Data and Analysis Populations

The registry record lists several outcomes and analyses. It does not report whether the trial prespecified a primary outcome hierarchy beyond identifying graft vascularity as the primary endpoint, whether secondary analyses were confirmatory or exploratory, or whether any multiplicity adjustment was used. When several statistical tests are considered, the chance of at least one apparently notable result can increase. General methods for addressing this include prespecified hierarchies or adjustments to the testing procedure, but the record does not say that any particular approach was used.

The primary endpoint should therefore be distinguished from the secondary outcomes. The primary comparison has a stated endpoint and follow-up, while the secondary results provide additional information subject to the uncertainty created by multiple testing. Without a reported multiplicity plan, secondary p-values should not be interpreted as if each were the sole planned test. The record does not provide enough information to assess whether the sponsor's analysis controlled for multiple comparisons.

The posted primary results have analysis counts of 28 for Transportal and 26 for Outside in. The registry gives overall enrollment as 67, while the brief summary describes 66 patients and 33 in each group. The registry record does not explain these differing counts or report participant flow, reasons for missing outcome data, or the number assessed at each follow-up. It also does not state how missing measurements were handled, whether any imputation was used, or whether the analysis included all randomized participants.

The analysis population is not reported in the registry record. In particular, the record does not state whether the analyses followed intention-to-treat, per-protocol, or another defined population. These distinctions matter because exclusions or missing outcomes after randomization can affect how representative the observed group comparisons are of the randomized groups. No direction or size of any such effect can be inferred from the available information.

The record identifies the trial as randomized and single-masked, but additional procedural details are not reported. Sequence generation, allocation concealment, the identity of masked parties, and the handling of protocol deviations are not reported in the registry record. These omissions limit assessment of the analysis and its vulnerability to bias; they do not establish that any particular problem occurred.

16. 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 zero serious adverse events in the Transportal group among 28 at risk and zero in the Outside in group among 26 at risk. It also reports zero other adverse events in the Transportal group among 28 at risk and zero in the Outside in group among 26 at risk. Deaths are recorded as zero in both groups. No serious adverse-event terms are listed.

These figures describe the adverse-event counts recorded in the registry for the stated groups. They do not establish that no adverse events occurred outside the categories or observation process recorded, and they do not show that the procedures have no risks. The registry record does not report event definitions, monitoring methods, or the adverse-event observation period. The counts should therefore be read as reported registry data, not as a complete assessment of safety or as a comparison powered to detect differences in uncommon events.

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

The primary posted result is a higher mean normalized graft vascularity ratio in the Outside in group than in the Transportal group at one year after surgery. The estimated unadjusted difference is 1.6, and the reported interval runs from 0.387 to 2.813. The sponsor's two-sided test reports p = 0.008. These statistics describe the observed comparison on this imaging endpoint.

They do not establish that the observed difference is clinically important. The registry record does not report a threshold for a meaningful difference in the normalized ratio, nor does it establish that this imaging measure predicts later symptoms, function, graft failure, or other patient outcomes. An imaging result should not be treated as equivalent to a clinical benefit.

The findings also do not settle the overall comparison between the procedures. Secondary outcomes address other dimensions, and the sponsor-reported and recalculated results are not uniform across them. The record does not report a multiplicity plan, complete participant flow, or missing-data approach. These limitations affect how strongly secondary evidence can be interpreted and how confidently the analyzed groups represent all randomized participants.

The trial was randomized, but the registry record does not give sufficient detail to assess all aspects of implementation and analysis. It reports one-year graft vascularity, one-year graft maturity, and two-year instability, but not a long-term outcome assessment. The primary result therefore applies to the stated endpoint and follow-up, rather than establishing a lasting difference across all outcomes.

Finally, the posted result is a group-level comparison. It does not predict the outcome for an individual participant. The statistics quantify observed group differences and uncertainty under the stated calculations; they do not make a treatment recommendation or provide a complete account of benefits and harms.

18. Why This Trial Matters Statistically

This trial illustrates why statistical interpretation benefits from separating the endpoint, the estimated group difference, and the evidence against a no-difference model. The primary outcome is a normalized imaging ratio, while the secondary outcomes address other measures. A statistically distinguishable group mean on the imaging endpoint is not automatically a clinically meaningful difference, and the registry record does not supply a threshold that would connect the two.

The record also makes it possible to distinguish the sponsor's reported analysis from an unadjusted recalculation using posted summaries. The primary p-values are close, and the recalculated interval provides a sense of the range of differences compatible with that calculation. For secondary results, sponsor and recalculated p-values do not align as closely. Keeping these analysis sources distinct avoids treating a summary-statistic recalculation as if it were the complete trial analysis.

The different analysis counts in the registry enrollment descriptions and posted endpoint results highlight the importance of participant flow and analysis populations. Without an account of missing outcomes and exclusions, readers cannot determine why the analyzed groups differ from the registry's other counts. That uncertainty is relevant even when the reported comparison is clearly described.

Finally, the planning illustrations demonstrate how required sample sizes depend on the effect assumed for future planning: smaller target effects require more participants for the same power target. They are not evidence about the original trial's design or retrospective power. Together, these statistical distinctions help keep the conclusions proportionate to what the registry record actually reports.

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 registry record does not provide a participant-flow account explaining why the stated enrollment of 67, the brief-summary description of 66 patients, and the primary analysis counts of 28 and 26 differ. It does not report how many participants were assessed at each follow-up, why any observations were unavailable, or how missing data were treated. The analysis population is not reported.

The record gives limited detail about trial conduct and statistical methods. Although it identifies randomization and single masking, it does not report sequence generation, allocation concealment, who was masked, or the sponsor's full model specification. The confidence level for the posted interval is not reported. These omissions restrict evaluation of the precision and potential sources of bias beyond the summary statistics.

The record does not report a clinically important threshold for the primary normalized imaging measure or establish its relationship to patient-centered outcomes. It also does not report a multiplicity procedure for the several outcomes. The secondary comparisons should therefore be interpreted cautiously, particularly where sponsor-reported tests and recalculations differ.

Follow-up periods vary by outcome, and the record does not provide long-term results beyond the stated timeframes. The adverse-event information is limited to the posted counts; definitions, observation periods, and ascertainment methods are not reported. These are limitations of what can be concluded from the registry record and do not show that an unreported procedure or analysis was absent from the full study conduct.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Comparison of Femoral Tunnel and Clinical Outcome Using Two Anterior Cruciate Ligament Reconstruction Techniques — NCT02754674.
• Registry record last updated 2019-12-20; status last verified 2017-12.
• Results first posted 2019-12-20.
• 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

NCT02754674 is a completed randomized, single-masked, parallel-group trial comparing transportal anterior cruciate ligament reconstruction with single-bundle outside-in reconstruction with remnant preservation. The primary endpoint is normalized graft vascularity measured by dynamic contrast-enhanced MRI one year after surgery. The registry reports means of 2.5 for Transportal and 4.1 for Outside in, with a recalculated unadjusted mean difference of 1.6 and sponsor-reported p = 0.008.

The registry also lists secondary outcomes, including instability and graft maturity, and reports no serious adverse events, other adverse events, or deaths in the posted group counts. Enrollment descriptions differ from the primary endpoint analysis counts, and reasons are not reported. The registry record does not report the original sample-size justification, missing-data approach, analysis population, or multiplicity plan. The findings should be read as comparisons on the specified outcomes and follow-up periods, with uncertainty about clinical importance and the unreported analysis details.