This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Large Head X3 Study (NCT02543437), a na na study. The primary outcome is Range of Motion(ROM) (Degree).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02543437 |
| Phase | NA |
| Condition | Degenerative Joint Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 120 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Stryker Japan K.K. |
| Results posted | Yes |
2. Clinical Question
Population
Participants undergoing computer-assisted total hip arthroplasty for degenerative joint disease in the Japanese population were the focus. The registry lists an enrollment of 120. For the primary outcome, it reports available data from 119 hips in 117 participants.
Intervention
The device was the Trident Acetabular X3 Insert, described as having 28mm, 32mm and 36mm liners. The study summary describes intraoperative assessment using a Stryker CT-based navigation system.
Comparator
The primary outcome description specifies a comparison using femoral head trials of 28mm and 36mm. The record identifies a single-group model and does not describe a randomized control group. Its stated purpose also includes observing X3 wear resistance in relation to historical highly crosslinked polyethylene liners.
Primary question
What range of motion, measured in degrees during the operation, was observed when the 28mm and 36mm femoral head trials were used? The registry defines the comparison and outcome, but the outcome values are not reported in the registry record.
3. Trial Design
NCT02543437, titled Large Head X3 Study, was a single-group device study focused on the Trident Acetabular X3 Insert. The record lists degenerative joint disease as the condition and describes the intended population as Japanese. The listed enrollment is 120. The registry dates the study start to 2010-07 and primary completion to 2011-12; its status is UNKNOWN.
The primary endpoint was intraoperative range of motion in degrees. Its description specifies comparing femoral head trials of 36mm and 28mm during intraoperative confirmation. The arm description lists 28mm, 32mm and 36mm liners, while the stated primary comparison is between the 28mm and 36mm sizes. The study summary also mentions lift-off distance as an aspect to examine, but the record does not identify it as the primary outcome.
The allocation field is NA, masking is NONE, and the model is SINGLE GROUP. The registry therefore does not describe a randomized parallel-group comparison. The two head sizes are described as part of an intraoperative assessment, not as independently randomized arms. Whether the measurements were analyzed as paired observations is not reported in the registry record.
The record identifies wear rate as a secondary outcome and describes interest in wear resistance compared with historical highly crosslinked polyethylene. It does not give the historical comparison group's details or a reported wear result. The sponsor is Stryker Japan K.K. The primary-outcome description reports available data from 119 hips in 117 participants; the registry does not explain the relation between the enrollment figure and those available data.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: 117 participants / 120 hips enrolled in study.
Overall Study
| Stage | Trident Acetabular X3 Insert |
|---|---|
| STARTED | 117 |
| COMPLETED | 117 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Comparison between 28mm liner and 36mm line. Participants with available data : 119 hips in 117 participants.
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.
| Characteristic | Unit | X3 Liner |
|---|---|---|
| Participants analysed | 117 | |
| Age, Continuous | years | 63.3 (SD 9.1) |
| Sex: Female, Male: Female | Participants | 100 |
| Sex: Female, Male: Male | Participants | 17 |
| Region of Enrollment: Japan | participants | 117 |
6. Primary Endpoint
The registry lists the primary outcome as Range of Motion(ROM) (Degree), measured over Intraoperative.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Degree |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is range of motion, abbreviated ROM, measured in degrees during the operation. The registry describes comparing femoral head trials of 28mm and 36mm during intraoperative confirmation, with the mean and standard deviation specified as the summary measures. ROM is a continuous measure: it records an amount on a scale rather than assigning participants to categories such as improved or not improved.
As a general measurement concept, an angular range describes how far movement extends under the conditions in which it is assessed. In this study, the assessment was intraoperative and the study summary says it used a CT-based navigation system. The endpoint can therefore address the immediate mechanical range observed during that assessment. It is not, by itself, a measure of later function or a patient-reported experience.
The registry describes lift-off distance in the study summary, but does not identify it as the primary endpoint in the available record. The listed primary outcome is ROM. Although its definition and summary-statistic type are recorded, the actual means, standard deviations, contrast between sizes, and uncertainty estimates are not reported in the registry record. The endpoint definition alone does not establish the direction or size of any observed difference.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record specifies a primary ROM comparison, but it does not report numerical ROM results. It gives no mean for either head size, standard deviation, estimated contrast, confidence interval, or p-value. As a result, the posted record does not show the observed magnitude or precision of the primary comparison. No conclusion about the direction or size of the ROM difference can be drawn from the endpoint description alone.
For the primary outcome, available data are stated as 119 hips in 117 participants. These are different units of observation: the record reports both hips and participants, and does not explain whether each participant contributed one or more measured hips. It also does not report the statistical treatment of any within-participant relationship. That distinction matters when interpreting uncertainty because measurements from the same participant may not provide independent information. Whether that issue arose in the analysis, and how it was handled, is not reported in the registry record.
The record lists three outcome measures overall, identifies ROM as primary, and names Wear Rate(%) as a secondary outcome. It does not report the wear-rate result or identify the full set of other outcome details. The number of analyses recorded is 0. That does not establish that no analysis was conducted; it means that analyses are not recorded in the registry information described. No analysis model or inferential result is available to assess.
The adverse-event entry lists zero participants at risk and zero affected for serious and other events, and deaths is null. With zero listed at risk, those entries do not provide an interpretable event rate or establish that no events occurred. The registry record does not report an adverse-event analysis population or additional event details.
Overall, this record describes a planned intraoperative comparison and the study's intended interest in wear. It does not supply outcome estimates with which to assess effect size or statistical precision. Registry status is UNKNOWN, and the record does not establish whether all intended results were posted elsewhere or whether follow-up reporting was completed.
9. Statistical Methods Explained
The registry classifies the primary measure as continuous and specifies a mean with standard deviation. Those choices describe how a numerical outcome was intended to be summarized. They do not themselves reveal the observed outcome or the method used to compare the two head sizes. The primary outcome description is intraoperative ROM in degrees, but numerical summaries and an inferential analysis are not reported in the registry record.
What does a mean describe?
As a general statistical explanation, a mean is a measure of the central level of a set of numerical observations. It can give a compact description of the observed ROM under each assessment condition. A mean does not show how widely observations vary, whether the distribution is symmetric, or how precisely the mean has been estimated. Those questions require additional information and an analysis suited to the study design.
What does the standard deviation add?
The standard deviation describes the spread of individual observations around their mean. It is not the same as the uncertainty in the estimated mean, and it is not a range containing every observation. If observations vary substantially, the mean alone can conceal meaningful heterogeneity. Here, the registry specifies standard deviation as the dispersion measure but does not report its value for either head size.
How should uncertainty be assessed?
In general, a confidence interval expresses the precision of an estimated quantity under the assumptions of the analysis. A narrower interval indicates greater precision than a wider interval, while the interval's location describes which effect sizes remain compatible with the data and model. A confidence interval does not correct a biased design or an unsuitable analysis. No confidence interval for ROM is reported in the registry record, so the precision of the primary comparison cannot be judged from the posted outcome information.
A comparison of two measurements is often expressed as a contrast, such as the difference between their means. That contrast would need to reflect the actual data structure. The record describes a single-group study and an intraoperative comparison using two head sizes; it does not document randomized allocation to separate groups. It also does not say whether measurements from the two conditions were paired at the hip or participant level, or how repeated or related observations were modeled. Those details are important because a method that treats related measurements as independent can misstate uncertainty. The specific analysis is not reported in the registry record.
Why do the design details matter?
In general, a randomized comparison can help balance measured and unmeasured differences between assigned groups, while an intraoperative comparison within a study may address a different question and depends on its measurement and analysis structure. This record lists allocation as NA and the model as SINGLE GROUP. Its primary description sets out a comparison of two head sizes, but it does not describe randomization or a separate control arm. The comparison should therefore be understood according to that recorded design rather than as evidence from a randomized parallel-group trial.
The brief summary says that a CT-based navigation system was used for intraoperative assessment. Consistent measurement procedures can support comparability, but the registry does not report calibration details, measurement reproducibility, assessor procedures, or a statistical model. No assumption about these features can be verified from the record.
What do the planning assumptions mean?
The planning assumptions describe illustrations using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They define the effect to detect as a stated fraction of the observed effect. Those are planning assumptions, not a description of the trial's own single-group design or an observed treatment effect. Any sample-size illustration based on them is not observed power and should not be interpreted as a result of the study. The registry record does not report a sample-size justification for the original study or its own design calculations.
More generally, planning calculations depend on a target effect, variability, analysis method, and design assumptions. When the observed effect used as a reference is not reported, the resulting planning context cannot be independently interpreted from the registry record. Such illustrations can communicate how assumptions affect planning, but they do not demonstrate that a study was adequately powered or that an effect was present.
The record lists 0 analyses. It does not identify a model, a test, a confidence-interval procedure, a missing-data method, or a multiplicity strategy. Consequently, the mean-and-standard-deviation specification should be read as the registered summary format, not as a complete statistical analysis plan.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies ROM as the primary outcome and Wear Rate(%) as a secondary outcome, while recording three outcome measures overall. It does not provide a complete description of all three measures or an analysis hierarchy. The number of analyses recorded is 0, and no multiplicity adjustment, testing sequence, or rule for interpreting multiple outcomes is reported in the registry record.
As a general statistical matter, examining multiple outcomes or multiple contrasts can increase the chance of observing a seemingly notable result by chance. A prespecified hierarchy or adjustment can help clarify how that risk is handled. The registry information does not state whether such an approach was used, so the risk cannot be assessed from the posted record. This is especially relevant to interpretation of the stated interest in ROM, lift-off distance, and wear, but the record does not identify all analyses that may have been conducted.
The primary outcome description reports available data from 119 hips in 117 participants. It does not report how much data were missing, why observations were unavailable, or whether the available-data group differed from those without recorded measurements. The relationship between hips and participants, and the analysis population used for the comparison, is also not specified.
No imputation procedure, sensitivity analysis, exclusion rule, or missing-data assumption is reported. In general, the effect of missing observations depends on why data are absent and on how the analysis handles them; a count of available observations alone cannot resolve that issue. The listed enrollment of 120 is not enough to determine the number or reasons for missing primary-outcome observations, and no such calculation is made.
11. What the Result Does, and Does Not, Mean
The record establishes that the study intended to assess intraoperative ROM using 28mm and 36mm femoral head trials in the context of the Trident Acetabular X3 Insert. It also records an intended interest in wear resistance and lists wear rate as a secondary outcome. These details explain the study question, but they are not outcome findings.
The registry does not report the ROM means, standard deviations, comparison estimate, confidence interval, or p-value. It therefore does not show whether the two head-size assessments differed, how large any difference was, or how precisely it was estimated. Similarly, the record does not report the secondary wear-rate result or a result of comparison with historical liners. The absence of those results in this registry record should not be converted into a claim that there was no effect or no difference.
The design information also limits what can be inferred. The registry lists a single-group model and does not describe random allocation or a randomized control group. The primary outcome is an intraoperative measurement, not a reported long-term clinical outcome. The intended historical wear comparison is mentioned, but comparator details and comparative findings are not reported. These features do not establish what the device would do in other settings or what later outcomes might be.
The adverse-event entry lists zero participants at risk and zero affected for serious and other events, with deaths recorded as null. Those entries do not provide a usable basis for estimating safety outcomes. They should not be read as proof that no adverse events occurred.
In general, statistical significance, clinical importance, and precision are different considerations. A p-value alone would not describe the size or practical importance of a result, while an estimate without its uncertainty could be difficult to interpret. Since these numerical results are not reported in the registry record, none of those aspects can be evaluated from the posted information.
12. Why This Trial Matters Statistically
This study raises a useful statistical distinction between a device comparison and a randomized treatment comparison. The registry describes one study group and an intraoperative assessment using different femoral head sizes. The primary question concerns an immediate measured range of motion, while the stated wear interest refers to comparison with historical liners. These are different comparisons and require clear descriptions of measurement, comparator, and analysis to support interpretation.
The record also illustrates why the unit of analysis matters. It reports primary-outcome data in both hips and participants. If observations from the same participant are related, an analysis may need to account for that dependence. The record does not say how the data were structured or modeled, so the stated counts alone do not establish the effective information available for the comparison.
Another statistical issue is the distinction between a defined endpoint and a reported result. ROM is specified in degrees, with mean and standard deviation as intended summary measures, yet the numerical findings and uncertainty estimates are not present in the registry record. Without them, readers cannot assess effect size or precision. The same limitation applies to the secondary wear-rate outcome.
The planning assumptions also show why sample-size illustrations should be separated from the original study design. Assumptions involving equal allocation between two arms and a normal approximation are not a substitute for documentation of the study's own design or statistical plan. Planning scenarios can be informative, but they cannot stand in for observed results or establish adequate power.
For biostatistical interpretation, the most consequential gaps are the unreported outcome estimates, analysis method, handling of potentially related measurements, missing-data approach, and multiplicity strategy. Those details would be needed to evaluate how the observations support any estimate and how much uncertainty surrounds it.
13. 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 describes the study as SINGLE GROUP, with allocation listed as NA and masking as NONE. Although the primary endpoint involves comparing head sizes during intraoperative assessment, the record does not describe randomized allocation or a separate control arm. This limits interpretation as a controlled comparison and makes the details of the within-study measurement and analysis especially important.
The primary endpoint is an intraoperative measurement. The registry record does not report follow-up results for later function, durability, or other clinical outcomes. Its study summary mentions lift-off distance, but the record identifies ROM as primary and does not provide a lift-off result. The intended assessment of wear resistance relative to historical highly crosslinked polyethylene is also not accompanied by comparator details or a posted wear result.
The available-data statement uses both hips and participants: 119 hips in 117 participants. The record does not specify whether observations were paired, whether both hips could contribute for a participant, or how any such dependence was handled. This leaves uncertainty about the analysis unit and the method used to estimate precision.
Although the record lists three outcome measures, it identifies only ROM as primary and Wear Rate(%) as secondary in the available information. It records 0 analyses and does not report analysis methods, confidence intervals, missing-data handling, multiplicity procedures, or a sample-size justification. These omissions prevent a detailed assessment of the inferential plan and the robustness of any findings.
The registry lists enrollment of 120 but does not explain the relationship between that figure and the primary-outcome available-data statement. Study status is UNKNOWN. The adverse-event entries list zero at risk and zero affected, with deaths null, so they do not establish an interpretable safety profile.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Large Head X3 Study — NCT02543437.
- Registry record last updated 2018-10-15; status last verified 2018-09.
- Results first posted 2016-04-06.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
17. Record Summary
NCT02543437 is the Large Head X3 Study, sponsored by Stryker Japan K.K. The record describes a single-group device study involving the Trident Acetabular X3 Insert in a Japanese population with degenerative joint disease. Listed enrollment is 120; the recorded start is 2010-07 and primary completion is 2011-12. Status is UNKNOWN.
The primary endpoint is intraoperative ROM in degrees, comparing 28mm and 36mm femoral head trials. The record specifies mean and standard deviation as summary measures and reports available primary-outcome data from 119 hips in 117 participants. Wear Rate(%) is listed as a secondary outcome, and the summary also mentions lift-off distance and interest in historical liner wear.
Numerical outcome results and analyses are not reported in the registry record. The record lists allocation as NA, masking as NONE, and 0 analyses. It does not provide the analysis method, missing-data approach, or multiplicity strategy. The adverse-event entries do not establish event rates because the listed at-risk counts are zero.