Outcomes of CPM Usage Following Arthroscopic Acetabular Labral Repair: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Outcomes of CPM Usage Following Arthroscopic Acetabular Labral Repair (NCT03407612), a randomized na study. The primary outcome is Change in Patient Satisfaction and Functional Outcome.

2. Clinical Question

The trial’s stated hypothesis was that CPM would reduce pain levels and pain medication use and improve function after hip arthroscopy. Analgesic usage and pain level are listed as secondary outcomes. The primary measure focuses on patient-reported function rather than pain itself, so the registered outcomes address related but distinct aspects of recovery. The registry record does not provide enough outcome results to determine the size, direction, or precision of the primary comparison.

3. Trial Design

The registry describes a randomized, parallel-group trial with no masking. Participants were assigned to CPM or no CPM. The trial is marked completed, and the listed enrollment is 54. The registry names Ohio State University as the sponsor. It records a study start date of 2013-02-15 and a primary completion date of 2015-06-25.

In the CPM arm, participants received a continuous passive motion device and were instructed to use it for 4-6 hours daily during the first two postoperative weeks following arthroscopic labral repair. The no-CPM arm did not receive CPM. The registry does not report details such as how the random sequence was generated, how assignment was concealed, or whether outcome assessors were masked. Those design details are not reported in the registry record.

Random allocation is intended, in general, to make groups comparable with respect to both measured and unmeasured characteristics at the start of a trial. It does not guarantee that the groups will be identical, particularly in a trial with limited enrollment. A parallel design means participants were assigned to an arm rather than receiving both approaches in sequence. With no masking, participants and relevant study personnel could know the assigned approach; the registry does not specify which personnel knew assignments or how this might have been addressed during outcome assessment.

The primary outcome was HOS ADL, assessed at baseline and at 6 weeks, 12 weeks, and 6 months postoperatively. The registry also lists analgesic usage and pain level as secondary outcomes. It does not report the arm-specific participant flow, the number contributing data at each time point, or the analysis population used for the outcome analyses. Those details 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 Change in Patient Satisfaction and Functional Outcome, measured over Baseline and 6 weeks, 12 weeks, and 6 months postoperatively.

The registered primary outcome is titled “Change in Patient Satisfaction and Functional Outcome,” but its description specifies the Hip Outcome Score Activities of Daily Living questionnaire. The questionnaire measures reported ability in daily activities after hip arthroscopy. Its score ranges from 0 to 100, with a higher score corresponding to a greater level of function. The registry says it was completed at baseline and at 6 weeks, 12 weeks, and 6 months postoperatively, and that improvement from the preoperative score to the 6-month postoperative score was also computed.

A functional questionnaire is useful because it captures the participant’s reported experience in daily activities, an aspect of recovery that may not be represented by a clinical event count alone. A baseline measurement also gives context for interpreting follow-up scores: a later score can be considered alongside the participant’s starting score. In general, a change score describes the difference between measurements over time, while a follow-up score describes status at a particular time. These summaries answer related but not identical questions.

The registry’s description does not specify a separate satisfaction instrument, despite the outcome title. It also does not report the primary-outcome estimates, variability, or statistical comparison. Thus, the score’s meaning and schedule are described, but the magnitude and precision of any difference between arms are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a continuous measure summarized by a mean and standard deviation. In general, a mean describes the center of a set of measurements, while a standard deviation describes how spread out individual measurements are around that mean. Neither quantity alone gives the uncertainty in a comparison between arms. For that, readers need an estimate of the contrast and a measure of its uncertainty, such as a confidence interval. The registry record does not report the primary arm-specific means, standard deviations, or a selected between-arm estimate.

What does a mean comparison describe?

For a continuous outcome such as HOS ADL, a comparison of means asks whether the average score differs between the assigned groups for a specified time point or change measure. A difference in mean scores is expressed in the score’s units—in this case, units on a scale. The interpretation depends on exactly which summary is compared: a follow-up score, a change from baseline, or another defined summary. The registry mentions both repeated HOS ADL measurements and improvement from the preoperative score to the 6-month postoperative score, but does not identify one numerical comparison as the primary result.

In general, a confidence interval describes uncertainty around an estimated effect under the assumptions of the analysis. A narrower interval indicates greater precision than a wider interval, but precision is not the same as clinical importance. A p-value addresses compatibility between observed data and a specified statistical model under a null hypothesis; it does not measure the probability that the null hypothesis is true or the size of an effect. No such primary comparison statistics are reported in the registry record.

Why does the time point matter?

HOS ADL was scheduled at baseline and at 6 weeks, 12 weeks, and 6 months postoperatively. Repeated assessments can describe how outcomes develop over follow-up, but they also create choices about which time point or summary should anchor the main interpretation. A comparison at 6 weeks answers a different timing question from a comparison at 6 months. A change score uses the baseline measurement in its definition, whereas a follow-up score focuses on status at that visit. The registry record does not report a single selected time-point comparison or the statistical method used to handle repeated measurements.

In general, repeated observations from the same participant are related rather than independent. Statistical methods for repeated measurements need to account for that relationship if they analyze multiple time points together. The particular model, covariance assumptions, and handling of incomplete follow-up are not reported in the registry record. It would be inappropriate to infer which approach was used from the fact that assessments were scheduled repeatedly.

What can the planning assumptions tell readers?

The registry describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. The stated effect to detect is a fraction of the observed effect. These are planning assumptions, not a description of the trial’s original design or a report of its observed power. The registry record does not report the trial’s own sample-size justification or any numerical planning results in the registry record for this interpretation.

In general, a planning calculation estimates how many participants per arm might be needed to detect a chosen effect under specified assumptions. Its output depends on the effect used, outcome variability, significance level, allocation, and power target. When the effect is drawn from an observed estimate, that estimate may itself be uncertain. Such calculations are illustrations of future-study requirements; they do not establish the probability that the completed trial detected an effect. No observed-power claim follows from a planning calculation.

Why is analysis detail important?

Randomization supports a comparison based on assigned groups, but the statistical interpretation still depends on who was included in each analysis, how missing outcomes were addressed, and whether the analysis followed assignment. The registry identifies the design as randomized and parallel, but the analysis population, missing-data method, covariate adjustment, and specific test or model are not reported in the registry record. No recalculated estimate is available from the posted outcome details, so there is no basis for a separate unadjusted recalculation or a comparison with a sponsor analysis.

In general, over-dispersion matters when observed variability exceeds what a chosen statistical model expects. A model that understates variability can produce intervals that are too narrow and tests that are too optimistic. This concern is relevant to outcomes whose variability may not fit a simple model, but the registry entries do not establish that over-dispersion occurred or identify a model for which it should be assessed. It should therefore be treated as a general statistical consideration, not as a trial-specific finding.

10. Multiplicity, Missing Data and Analysis Populations

The record lists 3 outcome measures and 6 analyses. It identifies HOS ADL as the primary outcome, with measurements at baseline and at 6 weeks, 12 weeks, and 6 months postoperatively. It also lists analgesic usage and pain level as secondary outcomes. Considering several outcomes, times, or analyses can create multiplicity: the more comparisons considered, the greater the chance that at least one appears noteworthy by chance if each is judged separately.

In general, researchers can address multiplicity by defining a primary comparison in advance, using a testing hierarchy, or adjusting statistical thresholds or intervals. Such choices affect how a collection of results should be interpreted. The registry entries do not report whether a multiplicity strategy was planned or applied, which analyses correspond to the listed outcomes, or whether the six analyses were confirmatory or exploratory. Those details are not reported in the registry record. No conclusion about adjustment should be inferred from the count of analyses alone.

Missing-data information is also important for longitudinal outcomes. If participants do not complete a scheduled questionnaire, the available observations may not represent everyone assigned to an arm. In general, the extent and reasons for missingness, the analysis method, and assumptions about unobserved outcomes affect the interpretation of estimates. The registry does not report the number with HOS ADL data at each time point, reasons for missing measurements, or an imputation or modeling strategy. These details are not reported in the registry record.

The registry entries also do not describe the analysis population, such as whether all randomized participants were included according to assigned arm. The randomized design is recorded, but the handling of deviations from assignment and any exclusions from analysis are not specified. Without the analysis population and missing-data details, the completeness and robustness of any outcome comparison cannot be assessed from the registry record.

11. 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.

The serious adverse event figures list 0 events in the CPM Used group, with 19 participants at risk, and 0 events in the No CPM Used group, with 23 participants at risk. These are the posted group-specific counts and at-risk figures. They are descriptive safety data, not a formal estimate of the difference in risk between the groups.

A zero count means no serious adverse events were recorded in the relevant group for the registry entry. It does not prove that the underlying risk is zero, and it does not show that the two approaches have identical safety profiles. In general, event counts are interpreted in light of the number followed, duration of observation, completeness of reporting, and uncertainty around rare events. The registry entries do not specify the safety observation period, event definitions, or completeness of event collection.

The record does not report deaths in these group entries. That should not be read as a confirmed absence of deaths, because the death values are not reported in the registry record. The posted serious adverse event figures alone cannot establish a comprehensive safety comparison.

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

The registry record establishes that a randomized, parallel-group study compared CPM with no CPM after arthroscopic labral repair. It identifies a functional primary outcome, HOS ADL, and gives its scale direction and assessment schedule. It also records pain level and analgesic usage as secondary outcomes and provides group-specific serious adverse event counts. These registry entries describe the trial question and parts of its measurement plan.

They do not establish the size or direction of a functional effect. The primary outcome is described across several time points, but a single numerical comparison is not reported in the registry record. The record therefore does not support a statement that CPM improved function, worsened function, or made no difference. The same limitation applies to the secondary outcomes: their aims are listed, but their comparative results are not reported in the registry record.

In general, the absence of a reported statistical result is not equivalent to a null result. A conclusion of no meaningful difference would require an estimate with adequate precision and an interpretation tied to a prespecified threshold or other relevant context. Those elements are not reported in the registry record. Likewise, a non-significant result, if one existed, would not by itself show equivalence or rule out important effects.

The serious adverse event counts show that 0 events were recorded in each listed group, with the corresponding participants at risk as reported. They do not rule out rare harms or establish equal safety. Information about follow-up duration, event ascertainment, and deaths is not reported in the registry record.

Accordingly, the most defensible reading is bounded: the registry documents the comparison, intervention instructions, primary functional measure, and some safety counts, but not the primary effect estimate or enough analysis detail for an efficacy conclusion. Statistical interpretation should remain centered on what the record actually reports rather than on the study hypothesis or the labels of its outcomes.

13. Why This Trial Matters Statistically

This trial is statistically notable because it links a randomized intervention comparison to a patient-reported functional outcome measured repeatedly after surgery. HOS ADL has an interpretable direction: higher scores correspond to greater function. The record also distinguishes the primary functional outcome from secondary outcomes concerning pain level and analgesic usage. That separation matters because different outcome types can answer different questions about postoperative experience.

The design features also frame interpretation. Random allocation is recorded, while masking is recorded as none. In general, randomization is intended to reduce systematic baseline differences between arms, whereas lack of masking can leave participants or study personnel aware of assigned treatment. The registry does not specify who knew assignments or whether outcome assessment was protected from that knowledge, so the possible effect on reported outcomes cannot be quantified from this record.

Repeated HOS ADL assessments create a meaningful time dimension, but also require clarity about the primary time point and analysis. A score at 6 months and a change from baseline to 6 months are distinct summaries. The registry describes both repeated assessment and an improvement calculation, yet does not provide a single result for interpretation. This illustrates why clear outcome definitions and a prespecified comparison are important when a study collects several outcomes at several times.

Finally, the registry lists multiple outcomes and analyses, while the multiplicity approach and analysis details are not reported. Together with the lack of a posted primary estimate, this limits the strength of statistical conclusions that can be drawn from the record. The trial remains informative as a record of a randomized research question and its measurement plan, but the registry entries do not quantify the comparative functional result.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

A central limitation is that the registry record does not report a single numerical comparison for the primary HOS ADL outcome. It gives the scale, direction, and follow-up schedule, but not the arm-specific summaries, effect estimate, uncertainty interval, or test result needed to judge the observed contrast. The reported outcome title refers to satisfaction and functional outcome, while the description specifies HOS ADL; a separate satisfaction measure is not described.

The primary outcome spans baseline and multiple postoperative time points, with improvement from the preoperative score to the 6-month score also mentioned. The record does not identify a single selected primary time-point comparison. It does not report the method for repeated measurements, the analysis population, or handling of missing data and protocol deviations. These omissions prevent evaluation of whether the analysis aligns with the randomized assignment and whether incomplete follow-up could affect the estimate.

The registry records 3 outcome measures and 6 analyses, but does not report their full mapping, prespecified hierarchy, or multiplicity handling. Secondary outcome results for analgesic usage and pain level are not reported in the registry record. Thus, the stated hypothesis cannot be checked against comparative results in these domains.

For safety, the record lists 0 serious adverse events in each group and gives participants at risk, but does not specify the observation period, event ascertainment, or death results. A complete assessment of safety cannot be made from those counts alone.

Additional details—including random sequence generation, allocation concealment, participant flow by arm and visit, and the trial’s own sample-size justification—are not reported in the registry record. These are specific gaps in interpreting this trial, not evidence that a particular method was or was not used.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Outcomes of CPM Usage Following Arthroscopic Acetabular Labral Repair — NCT03407612.
• Registry record last updated 2020-10-08; status last verified 2020-09.
• Results first posted 2018-08-02.
• 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.

18. Record Summary

NCT03407612 is a completed randomized, unmasked, parallel-group study sponsored by Ohio State University. It compared continuous passive motion with no CPM after arthroscopic labral repair. The registry lists enrollment of 54 and study dates from 2013-02-15 to primary completion on 2015-06-25.

The primary outcome is HOS ADL, scored from 0 to 100, with higher scores indicating greater function. Assessments were scheduled at baseline and at 6 weeks, 12 weeks, and 6 months postoperatively. Analgesic usage and pain level are listed as secondary outcomes. The record reports 0 serious adverse events in the CPM Used group and 0 in the No CPM Used group, alongside their respective participants at risk.

A single primary-outcome comparison, secondary-outcome results, and key analysis details are not reported in the registry record. The available record therefore describes the study design and measurement plan but does not quantify the comparative functional result.