Lateral Versus Anterior Spanning External Fixator for Tibial Plateau Fractures: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Lateral Versus Anterior Spanning External Fixator for Tibial Plateau Fractures (NCT00610701), a randomized na study. The primary outcome is Quadriceps Strength.

2. Clinical Question

The comparison concerns the placement of the external-fixator pins, not a comparison between different fracture conditions. The primary outcome is a continuous measure of muscle strength. Its reported means describe the observed values in each arm, while the reported standard deviations describe how spread out those values were within each arm. Those summaries and the registry's test result address the stated one-year comparison. They do not, by themselves, describe the course of strength at each interim visit.

The endpoint description says that measurements were recorded at admission, 6 weeks, 3 months, 6 months, and 1 year, but only the final follow-up is reported for this purpose. The analysis therefore answers a narrower question than a full comparison of recovery over time. Interim values and a statistical analysis of trajectories are not reported in the registry record. Nor does the record provide a more detailed primary question specifying a target difference or a direction of clinical importance.

The registry lists 35 participants as enrollment, while the primary outcome summaries give 5 participants in the anterior arm and 9 in the lateral arm. Those are the group sizes attached to the reported endpoint summaries. Further information about the relationship between enrollment and the analyzed groups, including the number with missing endpoint measurements and reasons for missingness, is not reported in the registry record.

3. Trial Design

The study is listed as randomized, with a parallel-group model and no masking. The two interventions were anterior pin placement and lateral pin placement. In a parallel design, each participant is assigned to one study arm rather than receiving both placements as sequential study conditions. Random allocation is part of the registered design, but the method used to generate the allocation sequence, conceal assignments, or implement randomization is not reported in the registry record.

The registry identifies the sponsor as University of Missouri-Columbia. The study phase is listed as NA. Enrollment is recorded as 35. The study status is terminated; the reason for termination is not reported in the registry record. The recorded start is 2006-03, and primary completion is recorded as 2012-08. These administrative dates do not establish when each participant was enrolled or followed, and additional timing details are not reported in the registry record.

The primary outcome is quadriceps strength, expressed as a mean in Nm with standard deviation. The final reported time point is 1 year. The endpoint description also mentions measurements at admission, 6 weeks, 3 months, and 6 months, but says that only the final result is reported for this purpose. The posted result therefore gives an endpoint comparison at final follow-up rather than a set of results for every scheduled measurement.

Outcome summaries are reported for 5 participants in the anterior pin-placement arm and 9 in the lateral pin-placement arm. These are the group sizes associated with the quadriceps-strength summaries, not a full accounting of the registered enrollment. The number randomized to each arm, the number who received the assigned placement, and participant flow through follow-up are not reported in the registry record. The record does not give a detailed protocol, an explanation for the difference between enrollment and endpoint group sizes, or a reason why the study was terminated.

The registered analysis is a one-sided t-test. The result is reported only as p > 0.05, without a test statistic, exact p-value, confidence interval, or estimated between-arm difference. The record does not specify further details of the test, including the precise direction of the one-sided alternative or any adjustment for baseline strength. The statistical plan beyond the posted test is 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.

Population: initially based on power analysis for anticipated quad strength data, final numbers based on those completing study in each group

6. Primary Endpoint

The registry lists the primary outcome as Quadriceps Strength, measured over (admission, 6 weeks, 3 months, 6 months) 1 year.

Quadriceps strength is a continuous measure of the force generated by the quadriceps muscle, reported in Nm. The registry identifies the outcome parameter as a mean and the measure of dispersion as a standard deviation. The mean gives a summary of the measured strength in each arm; the standard deviation describes the variability of individual measurements around that arm's mean. Neither summary alone describes every participant's result.

Strength is used as the primary endpoint in this study because the stated purpose includes evaluating patients with tibial plateau fractures, and the registry specifically selects quadriceps muscle strength for the comparison of pin-placement strategies. The outcome can be expressed numerically and compared between the two groups. The registry does not explain the clinical rationale for selecting quadriceps strength, define a meaningful difference, or state how a strength difference should be interpreted alongside other aspects of recovery. Those details are not reported in the registry record.

The stated timeframe includes admission, 6 weeks, 3 months, 6 months, and 1 year. The description says interim time points were recorded but only the final result is reported for this purpose. The posted means and standard deviations are therefore tied to the 1-year final follow-up, not to all listed measurement occasions. A comparison of change from admission, or of the pattern of strength over time, is not reported in the registry record.

For this continuous endpoint, the anterior arm has a reported mean of 35.9 Nm and standard deviation of 10.7, based on 5 participants. The lateral arm has a reported mean of 39.6 Nm and standard deviation of 17.7, based on 9 participants. The registry does not provide confidence limits around those means or a confidence interval for the between-arm contrast.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

General explanation: A mean is an average that summarizes a set of measured values. A standard deviation describes how dispersed those values are around the mean. When individual observations are more spread out, the mean alone gives a less complete picture of what participants experienced. Neither statistic shows the distribution's full shape, and neither indicates whether every participant had a value close to the mean.

In the registry's one-year quadriceps-strength summaries, the anterior arm is reported with a mean of 35.9 Nm and standard deviation of 10.7, based on 5 participants. The lateral arm is reported with a mean of 39.6 Nm and standard deviation of 17.7, based on 9 participants. The units are given for the means; the record labels the spread as standard deviation. The summary values do not include the individual observations, so the exact pattern of participant-level measurements cannot be assessed from them.

What does the t-test assess?

General explanation: A t-test is a method for assessing evidence about a difference between group means. It relates the observed contrast to the variability and amount of data, under assumptions of the selected test. A one-sided test evaluates evidence in a specified direction rather than treating departures in either direction symmetrically. The registry reports a one-sided t-test, but the direction of its alternative hypothesis is not reported in the registry record. The details of any variance assumption or other implementation choices are also not reported.

The posted result is p > 0.05. This is a threshold-form result rather than an exact p-value. A p-value is calculated under a statistical model and a null hypothesis; it describes how unusual data at least as extreme as those observed would be under that framework. It is not the probability that the null hypothesis is true, nor does it measure the size or importance of a treatment effect. Since the exact value and test statistic are absent, the strength of evidence cannot be reconstructed from the reported p-value statement alone.

Why does a confidence interval matter?

General explanation: A confidence interval presents an estimate together with a range of values that reflect statistical uncertainty under the analysis method. It helps readers assess both the direction and precision of an estimated difference. A narrow interval indicates greater precision than a wide interval, although interpretation also depends on the study question and the meaning of the outcome. The registry does not report a confidence interval for the between-arm comparison or for either group mean. The registry record therefore does not show which sizes of difference are compatible with the data under an interval-based analysis.

Why are sample sizes and variability relevant?

General explanation: The precision of a comparison depends on the amount of information in the data and on how variable the outcome is. Smaller groups and greater variability generally make estimates less precise. Here, the endpoint summaries are based on 5 participants in the anterior arm and 9 in the lateral arm, and the reported standard deviations describe within-arm spread. Those features make it especially important not to read the group means as exact representations of the wider population. The registry does not supply a confidence interval with which to quantify uncertainty.

Planning calculations and observed results answer different questions. A planning illustration asks what sample size might be needed under stated assumptions to detect a specified effect. It does not show the probability that the completed study detected an effect, and it is not observed power. The available description characterizes planning illustrations as based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The illustrated effect is a stated fraction of the observed effect. These are planning assumptions, not evidence that the trial was designed using them. The original sample-size justification is not reported in the registry record.

What is not available for an independent recalculation?

General explanation: A recalculation from summary statistics can sometimes estimate an unadjusted group contrast and its uncertainty when the required information is available. Such a result would not automatically reproduce a trial's prespecified model or account for any covariates. In this record, the two-arm continuous endpoint comparison is identified as having values missing or not estimable for that purpose. There is no posted recalculated estimate or interval to compare with the registry's test.

The registry provides group means, standard deviations, and group sizes, but the available results do not yield a reported recalculation in the statistical output. No additional calculation should be inferred from the arm summaries. The sponsor-reported analysis remains the reported test result; the inability to present a recalculation does not establish that the sponsor's test is right or wrong. No discrepancy between the sponsor analysis and a recalculation is identified in the registry record.

How should the design affect interpretation?

General explanation: Randomization is intended to make assigned groups comparable on average at the point of assignment, while masking can reduce some forms of influence on care or outcome assessment. The record identifies the study as randomized and unmasked. It does not describe the randomization procedure, allocation concealment, outcome-assessor masking, or the handling of participants who did not contribute a final measurement. These missing details prevent a full evaluation of implementation and analysis populations.

The parallel design means the two placement strategies were assigned to separate arms. The posted analysis compares the one-year group means using a one-sided t-test. Interim measurement occasions are mentioned, but an analysis of repeated observations is not posted. No adjustment for baseline strength, no multiplicity procedure, and no prespecified analysis plan are reported in the registry record. Thus, the available statistical interpretation should remain confined to the reported endpoint and comparison.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("1-anterior Pin Placement", "2-lateral Pin Placement")
n   <- c(5, 9)
m   <- c(35.9, 39.6)
sp  <- c(10.7, 17.7)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  1-anterior Pin Placement  5  35.900  10.700  22.614  49.186
CARM  2-lateral Pin Placement  9  39.600  17.700  25.995  53.205

11. Analyses Reported by the Sponsor

The registry reports a one-sided t-test for the comparison of the two pin-placement groups, with the result stated as p > 0.05. It does not provide an exact p-value, test statistic, estimated contrast, or confidence interval. The posted arm summaries give the means, standard deviations, and group sizes for one-year quadriceps strength, but no recalculated two-arm continuous comparison is available. The reason given in the statistical record is that values are missing or not estimable for this comparison.

As a result, there is no independent recalculated estimate to set alongside the registry-reported test. The posted test should be described as the registry's analysis, rather than treated as confirmed by a separate computation. No discrepancy between the registry-reported analysis and a recalculation is identified. The missing recalculation also does not imply that the reported test is invalid; it means that the available statistical output does not support a direct numerical cross-check.

The registry does not report sufficient details to reconstruct the test fully, including the direction of its one-sided alternative. Nor does it provide an interval estimate that could show the precision of the comparison. Readers should therefore retain the distinction between the descriptive arm summaries and the reported inferential result. The p-value threshold is the only inferential result posted for this endpoint, and it does not establish equivalence or specify the range of differences consistent with the data.

12. Multiplicity, Missing Data and Analysis Populations

The registry identifies quadriceps strength as the primary outcome and describes measurements at admission, 6 weeks, 3 months, 6 months, and 1 year. Its endpoint description says interim measurements were recorded but only the final result is reported for this purpose. The reported primary comparison therefore concerns the final follow-up identified as 1 year. Results for the interim measurements are not reported in the registry record, and no analysis of the pattern over time is posted.

Multiplicity concerns arise when a study makes multiple statistical comparisons, such as testing several outcomes, time points, or subgroups. If many tests are conducted, the chance of at least one apparently unusual result can increase unless the analysis plan addresses that issue. That is a general statistical concern, not evidence that multiple testing occurred in this study. The registry record does not report an interim-testing plan, a multiplicity adjustment, or a detailed statistical analysis plan. It is therefore not possible to determine from the record whether any adjustment was planned or used.

The record lists one primary outcome measure and zero posted secondary outcomes. This does not establish that no other analyses were performed; it describes the outcomes posted in the registry record. A subgroup-analysis plan, if any, is not reported in the registry record. The one-sided nature of the posted t-test is stated, but the rationale and specified direction are not reported. The registry also does not provide a prespecified threshold for a clinically meaningful difference.

Missing-data handling is not described. The registry lists enrollment as 35, while the endpoint summaries include 5 participants in the anterior arm and 9 in the lateral arm. The record does not explain the participant flow from enrollment to those endpoint summaries, give reasons for unavailable outcome measurements, or state whether any imputation or sensitivity analysis was used. It also does not specify the analysis population, such as whether all randomized participants were included according to assigned group or only participants with observed endpoint data.

These gaps matter because the interpretation of a group comparison depends partly on which participants contributed data and how missing outcomes were handled. Without the analysis population, missingness reasons, and analysis plan, readers cannot assess whether the posted summaries represent all randomized participants or whether the analysis could be affected by missing data. The registry record does not report those details, so conclusions should be limited to the participants and results explicitly posted.

13. 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 0% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: death (22.2%), arthrofibrosis (20.0%), infection (11.1%).

The registry lists serious adverse events for 5 participants at risk in the anterior group, with 2 affected, and for 9 participants at risk in the lateral group, with 3 affected. Other adverse events are listed as affecting 0 of 5 at risk in the anterior group and 0 of 9 at risk in the lateral group. The record does not give a separate death count for either group; deaths are recorded as null.

The registry also lists the serious adverse-event terms death (22.2%), arthrofibrosis (20.0%), and infection (11.1%). The record does not explain the denominators or counting rules behind these percentages, nor does it link each listed term to a specific arm. They should not be interpreted as group-specific risks or as event counts. The null death fields and the listed death term are distinct registry entries, and the record does not clarify their relationship.

These figures are descriptive. The groups have different numbers at risk, and the record does not provide details about event timing, severity grading, relatedness to the intervention, or whether participants could contribute more than one event. Those details are not reported in the registry record. The adverse-event information therefore does not support a more detailed comparative safety estimate than the counts and listed terms displayed in the registry.

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

The registry result describes one randomized, parallel-group comparison of anterior and lateral pin placement, with one-year quadriceps strength as the primary endpoint. The reported mean is 35.9 Nm in the anterior arm and 39.6 Nm in the lateral arm. The reported standard deviations are 10.7 and 17.7, based on 5 and 9 participants, respectively. The registry reports a one-sided t-test result of p > 0.05.

These findings do not establish that the two placements have identical effects. A result reported as p > 0.05 is not an equivalence test, and the registry record does not report a prespecified equivalence or non-inferiority margin. The result also does not prove that one placement is better. The exact p-value, estimated between-arm difference, and confidence interval are not reported, leaving the precision of the comparison unclear.

The posted endpoint is limited to the final follow-up. Although interim visits are mentioned, their results are not reported for this purpose. The record does not provide an analysis of change from admission, recovery trajectories, or other primary outcomes. It also does not define a clinically important difference in strength. The statistics should consequently be read as a report of the measured outcome and test, not as a complete account of recovery or clinical importance.

Enrollment is listed as 35, but the outcome summaries include 5 participants in the anterior arm and 9 in the lateral arm. Without participant flow and missing-data information, the reasons that the reported endpoint groups are smaller than the enrollment entry cannot be determined. The analysis population and the handling of missing outcomes are not reported in the registry record. This limits confidence about how broadly the outcome summaries represent the randomized participants.

The trial status is terminated, but the reason is not reported. The registry record does not provide a sample-size justification, detailed protocol, or full statistical analysis plan. Its adverse-event entries also lack information needed for detailed arm-level interpretation. Taken together, the posted record permits a careful description of the reported endpoint summaries and analysis, but leaves important questions about precision, missing data, analysis choices, and safety-event interpretation unanswered.

15. Why This Trial Matters Statistically

This trial matters statistically because it illustrates the difference between reporting a group mean and establishing a precise comparative effect. The registry provides mean quadriceps-strength values, standard deviations, group sizes, and a threshold-form p-value. Those pieces of information are useful, but without an estimated contrast and confidence interval they do not show the range of between-arm effects compatible with the data under the analysis.

The endpoint summaries involve 5 participants in the anterior group and 9 in the lateral group. The registry lists enrollment as 35, but does not explain participant flow to the reported endpoint groups. This makes reporting the analysis population and missing-data handling especially important for readers trying to understand who is represented by the result. The issue is not resolved by the randomized design alone; interpretation also depends on how outcomes were observed and analyzed.

The one-sided t-test result is another useful point for statistical reading. Directional testing evaluates evidence in a specified direction, so knowing the intended direction and the rationale matters. The registry reports that the test was one-sided but does not report the alternative's direction. The threshold p-value also cannot replace an interval estimate or demonstrate equivalence.

Finally, the registry mentions multiple measurement occasions but reports only the final endpoint for this purpose. That distinction clarifies what the available result can answer: it is a comparison at 1 year, not a reported analysis of recovery over time. The record's gaps on the analysis plan, missing data, and multiplicity show why transparent reporting is important for interpreting even a simple two-arm outcome.

16. 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 posted record leaves several trial-specific questions unresolved. It lists enrollment as 35, while the one-year quadriceps-strength summaries are based on 5 participants in the anterior arm and 9 in the lateral arm. The registry does not provide participant flow, the number assigned to each group, reasons for unavailable endpoint measurements, or a description of the analysis population. Consequently, it is not possible to determine from the record how the endpoint groups relate to all enrolled or randomized participants.

The inferential result is limited to a one-sided t-test reported as p > 0.05. The registry does not give an exact p-value, test statistic, contrast estimate, confidence interval, or direction for the one-sided alternative. The record also does not report a baseline-adjusted comparison, a prespecified clinically meaningful difference, or a detailed rationale for the statistical method. The available summary does not permit a reported independent recalculation of the continuous two-arm comparison.

Measurements at admission, 6 weeks, 3 months, and 6 months are mentioned, but the endpoint description says only the final follow-up is reported for this purpose. Interim numerical results and a longitudinal analysis are not reported in the registry record. The record does not state how repeated measurements were handled statistically or whether interim analyses occurred.

The study is listed as unmasked, but the record does not explain whether outcome assessment was masked. It also does not describe allocation concealment, adherence to assigned placement, or the handling of protocol deviations. A detailed protocol, sample-size justification, and full statistical analysis plan are not reported in the registry record. The study status is terminated, but the reason is not reported.

Adverse-event entries provide affected counts and at-risk counts, but do not specify timing, event relatedness, or the denominators behind the listed serious-event percentages. Deaths are null in the group fields while death appears among listed serious terms; the record does not clarify that relationship. These reporting limitations constrain both the comparative efficacy interpretation and the interpretation of safety information.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Lateral Versus Anterior Spanning External Fixator for Tibial Plateau Fractures — NCT00610701.
• Registry record last updated 2017-07-24; status last verified 2017-06.
• Results first posted 2014-09-10.
• 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.

20. Record Summary

The registry describes a randomized, unmasked, parallel-group study comparing anterior with lateral pin placement for tibial plateau fractures. The sponsor is University of Missouri-Columbia, enrollment is listed as 35, and the study status is terminated. The primary outcome is quadriceps strength in Nm at final follow-up, identified as 1 year.

The anterior arm has a reported mean of 35.9 and standard deviation of 10.7, based on 5 participants. The lateral arm has a reported mean of 39.6 and standard deviation of 17.7, based on 9 participants. The registry reports a one-sided t-test result of p > 0.05. An exact p-value, confidence interval, and estimated contrast are not reported in the registry record.

Interim measurements are mentioned, but only the final result is reported for this purpose. The reason for termination, participant flow, missing-data handling, analysis population, sample-size justification, and detailed statistical plan are not reported in the registry record. The serious adverse-event entries include group counts and several listed terms, but do not give sufficient detail for a fuller arm-specific interpretation.