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 Kinematic Analysis: Posterior Stabilized, Fixed Bearing Total Knee Arthroplasty With Attune Knee System - Phase 2 (NCT02613338), a registered phase not stated study. The primary outcome is Femoro-tibial Kinematics - Lateral Anterior/Posterior Motion.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02613338 |
| Phase | Phase not stated |
| Condition | Total Knee Arthroplasty, Osteoarthritis |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 30 |
| Arms in the primary outcome | n/a |
| Lead sponsor | The University of Tennessee, Knoxville |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people who received a total knee arthroplasty for conditions including osteoarthritis. The registry record describes a planned analysis of 30 subjects after implantation; it does not provide further eligibility details or describe the characteristics of the analyzed participants.
Intervention
The device under study is the DePuy Attune posterior stabilizing fixed bearing knee system. The study focuses on knee motion after implantation, rather than on a comparison of alternative treatments.
Comparator
No comparison group is described. The registry record characterizes the study as not a randomized comparison, and allocation is not stated. The listed arm consists of patients implanted with the Attune system, so the record does not establish a like-for-like control comparison.
Primary question
At three months post-operatively, what is the mean lateral femoro-tibial anterior/posterior motion during deep knee bend, gait, and ramp down? The endpoint describes anterior sliding as positive and posterior rollback as negative. Although the question and measurement are specified, the registry record does not report the measured values or an analysis of them.
3. Trial Design
This completed Phase 2 study was designed to characterize knee kinematics after total knee arthroplasty with the DePuy Attune posterior stabilizing fixed bearing knee system. Its stated continuation was to analyze 30 subjects at three months post-operatively. The registry lists one device intervention and one corresponding group of patients implanted with that system. It does not describe a concurrent alternative-device or untreated comparison group.
The planned assessment used the University of Tennessee's mobile fluoroscopy unit while participants performed level walking, ramp down, and deep knee bend. The primary outcome concerns lateral femoro-tibial motion during those activities. The registry also lists maximum ground reaction force for deep knee bend, gait, and ramp down as secondary outcomes. It reports seven outcome measures overall, but does not provide a full account of the measures beyond the named outcomes in the record.
The record lists the study start as 2015-11, primary completion as 2018-12, and status as completed. These administrative dates do not establish when each participant was assessed or whether all planned assessments were completed. Participant flow, exclusions, and the number contributing data to each outcome are not reported in the registry record.
The record does not report a randomized allocation procedure or a control condition. It therefore describes a post-implantation assessment, not a randomized estimate of how the device compares with another system. The protocol details, sample-size justification, and statistical analysis plan are not reported in the registry record. The posted record also contains no analysis results for the primary endpoint.
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
| Stage | DePuy Attune PS FB Knee System |
|---|---|
| STARTED | 30 |
| COMPLETED | 30 |
| NOT COMPLETED | 0 |
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 | DePuy Attune PS FB Knee System |
|---|---|---|
| Participants analysed | 30 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 7 |
| Age, Categorical: >=65 years | Participants | 23 |
| Age, Continuous | years | 68.48 (SD 5.16) |
| Sex: Female, Male: Female | Participants | 15 |
| Sex: Female, Male: Male | Participants | 15 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | Participants | 30 |
6. Primary Endpoint
The registry lists the primary outcome as Femoro-tibial Kinematics - Lateral Anterior/Posterior Motion, measured over 3 months post-operative.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | mm |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is titled femoro-tibial kinematics—lateral anterior/posterior motion. It is a continuous measure, reported as a mean with standard deviation, in millimetres. Its description specifies the amount of anterior sliding of the lateral condyle, assigned a positive direction, and/or posterior rollback, assigned a negative direction. The planned measurement time is three months post-operatively.
The endpoint is intended to characterize how the lateral condyle moves relative to the femur during deep knee bend, gait, and ramp down. These activity-specific motion measurements address the study's stated interest in understanding knee-joint kinematics after implantation. The registry background discusses posterior femoral rollback, reverse axial rotation, and condylar lift-off as features of interest in posterior stabilizing knees, and presents the device design as intended to address restoration of kinematics more like those of a normal knee. That background explains the motivation; it is not evidence that the endpoint improved or that the device restored normal motion.
A mean describes the central level of the measured motion across observations included in an analysis, while the standard deviation describes variation among those observations. These are general statistical interpretations. The registry record does not report the activity-specific means, standard deviations, participant-level data, or a statistical comparison. It is therefore not possible to assess the observed direction, size, or precision of the primary endpoint from the posted results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record gives a clear description of the intended kinematic question but does not post the primary endpoint values or an analysis. It identifies lateral anterior/posterior motion in millimetres, measured three months after surgery during deep knee bend, gait, and ramp down. It also specifies that anterior sliding is positive and posterior rollback is negative. Without activity-specific results, however, no conclusion can be drawn from the posted record about the amount or direction of motion observed.
The endpoint is described as a mean with standard deviation. In general, a mean provides a summary of the measured values, while the standard deviation indicates how dispersed the individual observations are around that summary. Neither statistic alone shows how precisely a group mean is estimated; a confidence interval would help express that uncertainty. No confidence interval, standard error, p-value, or other inferential result for the primary endpoint is reported in the registry record.
The study has one listed intervention group and no stated comparator. Consequently, even if a within-group mean had been posted, it would describe the recorded motion in that group rather than establish the effect of the device relative to another treatment. A comparison intended to attribute differences to a device would require an appropriate comparison design and a reported analysis. The registry does not describe such a design.
The registry background provides a rationale involving knee kinematics and design goals, but rationale should not be confused with results. The statement that further in vivo analysis is necessary describes the study's motivation. It does not establish that the measured kinematics were closer to normal, nor does it demonstrate a change in wear, failure, or clinical outcomes. Those outcomes are not reported as results in this record.
The registry lists seven outcome measures and zero analyses. Its safety entries list zero serious adverse events, zero other adverse events, and zero deaths for the listed group, with 30 at risk for each adverse-event category. These entries should be read as registry-reported figures, not as proof that no event occurred outside the scope or reporting process represented in the record.
Overall, the posted information supports interpretation of the study's objective, measurement, and design limits, but not a quantitative interpretation of the primary result. The registry record does not report outcome estimates, uncertainty intervals, or analysis methods. The study is marked completed, but completion status alone does not supply those missing results.
9. Statistical Methods Explained
The primary outcome is continuous: lateral anterior/posterior femoro-tibial motion is measured in millimetres. The record specifies a mean as the summary parameter and standard deviation as the measure of dispersion. These terms describe different aspects of data. In general, a mean locates the center of a set of measurements, whereas a standard deviation describes how spread out the measurements are around that center. A standard deviation is not a confidence interval and does not, by itself, quantify uncertainty in the estimated mean.
A confidence interval is a general statistical tool for expressing the precision of an estimate. It gives a range of values compatible with the data and the chosen method, under the assumptions of that method. A narrow interval would indicate greater precision than a wide one, but precision is not the same as clinical importance. No confidence interval or other uncertainty estimate for the primary endpoint is reported in the registry record, so the precision of any activity-specific mean cannot be assessed from the posted information.
The endpoint's sign convention matters for interpretation. The record defines positive values as anterior sliding and negative values as posterior rollback. Any reported estimate would need to be read with that convention in mind, as well as with its activity and time point. Results for deep knee bend, gait, and ramp down would refer to distinct tasks, and a mean for one task should not be assumed to describe the others. The registry provides the planned activities but no numerical results for any of them.
In general, repeated measurements during different activities can vary because the tasks differ and because measurements within a participant may be related. Appropriate analysis should make clear how observations were grouped and whether repeated observations were accounted for. The registry record does not report the analysis model, how measurements across tasks were handled, or whether any adjustment was made. It is not possible to infer these choices from the stated endpoint summary.
The study's stated context concerns a single implanted device group. Without a comparator, the group mean is descriptive rather than a randomized treatment contrast. A comparison with a reference value would also require that reference and its rationale to be stated, neither of which is reported in the registry record. The study's background discussion of normal-knee kinematics does not itself define a statistical reference distribution or threshold.
General explanation: variability can be important when measurements differ substantially among participants or tasks. In some settings, over-dispersion—greater variability than a model assumes—can make standard errors too small and confidence intervals too narrow if it is ignored. Whether over-dispersion is relevant depends on the data structure and model. The registry record does not report participant-level distributions, model assumptions, or diagnostics, so no assessment of over-dispersion is possible for this study.
The registry lists maximum ground reaction force during deep knee bend, gait, and ramp down as secondary outcomes. These are distinct from the primary motion measure. In general, secondary outcomes can broaden the description of a study, but their interpretation depends on prespecified definitions, the analysis plan, and the results. The record does not report numerical results or detailed analytic methods for these outcomes.
The record notes that planning illustrations use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a fraction of the observed effect. It also states that such illustrations are planning calculations rather than observed power. These assumptions do not describe the actual study design: the registry lists one intervention group and no randomized comparison. The registry record does not report the trial's own sample-size justification or a calculation tied to a reported primary effect. Any planning illustration should therefore be distinguished from the evidence actually collected and analyzed.
Power is a design concept describing the chance that a specified analysis will detect a specified effect under stated assumptions. It is not a measure of whether a completed study produced a reliable result. A post hoc calculation based on an observed effect is not observed power and cannot replace an estimate with an uncertainty interval. The registry record does not report a power analysis for this trial, and the absence of outcome estimates means the primary effect and its precision cannot be evaluated from the posted record.
Finally, a p-value, if reported, would address how compatible data are with a specified statistical model and null hypothesis; it would not state the probability that the hypothesis is true or the size of a clinical effect. No p-value or hypothesis test for the primary endpoint is reported. Since the analysis methods and results are not posted, there is no basis to reconstruct an inferential analysis or to substitute an unadjusted calculation for a sponsor analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists seven outcome measures, including the primary kinematic outcome and secondary maximum ground reaction force outcomes for deep knee bend, gait, and ramp down. When a study evaluates multiple outcomes or multiple activity-specific measurements, the chance of at least one apparently unusual finding can increase if each is tested separately without accounting for multiplicity. This is a general statistical concern, not evidence that a particular adjustment was or was not needed in this study.
The registry record does not report a multiplicity strategy, an order of testing, or which analyses were considered confirmatory versus exploratory. It also does not report the detailed analysis plan. The status of the secondary outcomes and any adjustment for multiple comparisons are therefore not reported in the registry record. Without those details and the results, isolated findings cannot be evaluated in relation to the full set of outcomes.
Missing-data handling is also not described. The record states that the study planned to analyze 30 subjects at three months post-operatively, but it does not report how many contributed measurements to each activity or outcome, whether any assessments were missing, or how missing values were handled. The number enrolled or planned for analysis should not be assumed to equal the number contributing data to every endpoint.
The analysis population is not defined beyond the description of patients implanted with the device. The registry does not specify inclusion rules for the endpoint analyses, exclusions, or whether all available observations were used. These details matter because analysis populations can differ and can affect interpretation. No conclusion about the handling of missing data or the population underlying an estimate can be made from the posted record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| DePuy Attune PS FB Knee System | 0 | 30 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| DePuy Attune PS FB Knee System | 0 of 30 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| DePuy Attune PS FB Knee System | 0 of 30 |
The registry lists 30 participants at risk for serious adverse events and 30 at risk for other adverse events in the DePuy Attune PS FB Knee System group. It records zero serious adverse events, zero other adverse events, and zero deaths. No serious adverse-event terms are listed.
These are registry entries for the group and reporting period represented in the record. They do not describe event definitions, ascertainment procedures, follow-up completeness, or the method used to determine the at-risk population. Those details are not reported in the registry record. A zero entry should therefore be read as no events recorded in that category in the posted safety figures, not as proof that the device has no risks or that all possible events were captured.
The registry does not provide event-level details or a comparison group. As a result, the safety figures cannot estimate a comparative difference in risk, and they do not establish what might have occurred under another treatment. They are descriptive entries and should be interpreted within those limits.
12. What the Result Does, and Does Not, Mean
The study addresses a specific measurement question: how much lateral femoro-tibial anterior/posterior motion was observed three months after implantation during deep knee bend, gait, and ramp down. It focuses on a posterior stabilizing fixed bearing knee system and was intended to contribute in vivo information about knee kinematics. The registry also identifies maximum ground reaction force during the named activities as secondary outcomes.
What the posted record does not establish is the observed level of motion. It gives no primary endpoint means, standard deviations, confidence intervals, or inferential analyses. Thus, it cannot show whether motion was predominantly anterior or posterior, how much it varied, or how precisely it was estimated. Completion status and a description of the planned measurements do not substitute for results.
The record also does not show whether the measured motion was closer to that of a normal knee. The study background frames design goals and prior concerns, but the registry does not provide a normal-knee reference or a comparative analysis against one. Nor does it report polyethylene wear, implant failure, or other clinical outcomes as findings. The study's kinematic focus should not be read as direct evidence about those outcomes.
Because no comparison group is described, the record does not estimate how the device performs relative to another knee system. A single-group description can characterize observed measurements, but it cannot by itself isolate a device effect from other explanations. The registry does not provide enough information to assess the effect of the device or to make a causal comparison.
The safety entries report zero events in the listed categories, but these descriptive figures do not establish absence of risk. The registry does not describe the details needed to evaluate completeness or comparative safety. Overall, the record documents a completed study and its intended kinematic assessment, while leaving its primary numerical results and their uncertainty unreported.
13. Why This Trial Matters Statistically
This study is statistically notable for separating a clearly defined measurement question from the evidence needed to answer it. The registry specifies a continuous primary endpoint, its units, its direction convention, its summary measure, its dispersion measure, and the post-operative assessment time. It also names the activities during which motion was to be measured. These details make the intended estimand more interpretable than a broad claim about knee performance alone.
At the same time, a well-described endpoint does not itself constitute a result. Without the activity-specific estimates and uncertainty, readers cannot judge either the observed motion or the precision of its measurement. This is a useful distinction in clinical research: a registry can describe what was planned and still leave the central quantitative question unanswered in its posted results.
The one-group design also shapes what statistical conclusions are available. Descriptive measurements can characterize the implanted group, but the absence of a stated comparator means that the record does not support a randomized treatment contrast. The title's design focus and the background rationale should not be mistaken for comparative evidence.
The study further illustrates why reporting analysis populations, missing-data handling, and multiplicity plans matters. Several activities and outcomes are listed, but the registry does not explain how the analyses were conducted or whether all planned measurements were available. Without those details, readers cannot assess the robustness or scope of any result. In this record, the lack of posted analyses makes those questions especially consequential.
Statistically, the strongest conclusion is therefore about the study's planned measurement framework and the limits of what is reported. The record cannot support an estimate of the primary endpoint's magnitude or precision, or a comparative claim about the device.
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.
The principal limitation for interpreting this record is that it does not report numerical results for the primary endpoint. Although the endpoint is defined and the study is marked completed, the registry provides no activity-specific mean, standard deviation, confidence interval, or analysis. The registry reports zero analyses. Accordingly, the central kinematic question cannot be answered from the posted record.
The design information also limits causal interpretation. One intervention group is listed, and the record does not describe a comparator or randomized allocation. The registry notes that allocation is not stated and that the arms are not a like-for-like control comparison. The posted information therefore does not establish a comparative effect.
Participant-level information is limited. The record states that 30 subjects were to be analyzed, but does not report participant characteristics, flow through the study, endpoint-specific numbers analyzed, or missing-data handling. It also does not describe the analysis population. These omissions prevent assessment of selection, completeness, and the representativeness of the measurements.
The registry lists outcomes and activities but does not report a detailed statistical analysis plan, methods for handling multiple outcomes, model assumptions, or diagnostics. It does not provide a normal-knee reference for the stated design goal. The background rationale cannot fill those gaps or serve as a substitute for comparative outcome data.
Finally, the safety figures are limited to the registry's event counts and at-risk entries. Event definitions, ascertainment, follow-up completeness, and comparative safety data are not reported in the registry record. These limitations concern the record's available information and do not determine what may be contained in other study materials.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Kinematic Analysis: Posterior Stabilized, Fixed Bearing Total Knee Arthroplasty With Attune Knee System - Phase 2 — NCT02613338.
- Registry record last updated 2019-11-12; status last verified 2019-10.
- Results first posted 2019-11-12.
- 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.
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18. Record Summary
NCT02613338 is a completed Phase 2 study of the DePuy Attune posterior stabilizing fixed bearing knee system. The study planned to analyze 30 subjects three months after surgery using mobile fluoroscopy during level walking, ramp down, and deep knee bend.
The primary endpoint is mean lateral femoro-tibial anterior/posterior motion in millimetres, with standard deviation as the measure of dispersion. Anterior sliding is defined as positive and posterior rollback as negative. Secondary outcomes include maximum ground reaction force during the named activities.
The registry record does not report primary outcome values, analysis results, or detailed analysis methods. It lists zero serious adverse events, zero other adverse events, and zero deaths in the intervention group. The absence of a stated comparison group means the record does not provide a randomized comparative estimate.