Optimized Loading Response by JOURNEY II BCS Knee Increases Daily Physical Activity and Functions: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Optimized Loading Response by JOURNEY II BCS Knee Increases Daily Physical Activity and Functions (NCT02335710), a registered phase not stated study. The primary outcome is Kinematics Translations During Deep Knee Bend (DKB) Activity.

2. Clinical Question

3. Trial Design

This was a completed clinical study of knee kinematics associated with the Journey II BCS total knee arthroplasty. The registry record gives an enrollment of 50 and lists two groups: people implanted with the device and people with a normal knee. The record does not state that participants were randomly assigned, and it does not describe allocation procedures. These groups therefore should not be interpreted as randomized treatment arms or as a like-for-like control comparison.

The intervention was a device rather than a medicine or other assigned treatment. The implanted group was defined by receipt of the Journey II BCS TKA. The normal-knee group was described as having a healthy, functioning knee without osteoarthritis or knee pathologies. Differences between these groups could reflect their underlying clinical status and other characteristics, not only the presence or absence of the implant. Participant characteristics needed to assess comparability are not reported in the registry record.

The study objective describes evaluating in vivo kinematics for recipients of a second-generation Journey BCS TKA and comparing those patterns with normal knees and with first-generation Journey PS TKA patterns analyzed in a previous study. The first-generation group is not listed among the registry record’s study arms. Details of the previous study’s participants, measurements, and analysis are not reported in the registry record, so the historical comparison cannot be assessed from this record alone.

The study began in 2014-07, had a primary completion date of 2016-07, and is marked completed. The primary outcome timeframe is 3 months post-operative. The registry record lists eight outcome measures, but it does not provide primary outcome values or analysis entries. It also does not report the protocol, a statistical analysis plan, or a sample-size justification.

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 Kinematics Translations During Deep Knee Bend (DKB) Activity, measured over 3 months post-operative.

The primary endpoint is titled “Kinematics Translations During Deep Knee Bend (DKB) Activity.” It concerns anterior-posterior translations of the medial and lateral femoral condyles during a deep knee bend. The measurement unit is mm, and the stated summary parameter is a mean with standard deviation. The timeframe is 3 months post-operative.

In general, kinematic measurements describe movement. Tracking translation of the femoral condyles during a specified activity can characterize how the knee moves through that task. A deep knee bend offers a defined movement context in which to observe those translations. The endpoint is relevant to the stated study objective because the brief summary asks whether the revised implant is associated with normal-like kinematic patterns and whether weight-bearing knee flexion is greater than in the earlier design. However, the listed primary endpoint specifically describes translations; the registry record does not report a primary outcome value for either condyle or a result for weight-bearing knee flexion.

The endpoint description refers to medial and lateral condyles, but it does not explain whether these were analyzed as separate outcomes, combined in a particular way, or tested under a prespecified hierarchy. The record also does not give the measurement procedures, the definition of the movement phase, or the analysis population. Those details are not reported in the registry record. Without the numerical results and their uncertainty, the endpoint description identifies what was intended to be measured but does not show the observed movement patterns or establish how precisely they were estimated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a continuous primary outcome summarized by a mean and standard deviation. This means the intended analysis concerns measured values on a numerical scale, expressed in mm, rather than a simple count of participants with or without an event. The record does not report the actual measurements, estimates, or inferential results. The statistical concepts below are general explanations, not claims about analyses performed in this study.

What does a mean describe?

In general, a mean is an arithmetic summary of measured values in a group. It gives a central value that can be useful for describing average femoral-condyle translation during the specified activity. A mean alone does not show how similar or different individual measurements were. It can also be affected by unusually high or low observations, so it is ordinarily interpreted alongside a measure of variation and the study design.

What does the standard deviation describe?

In general, a standard deviation describes how spread out individual measurements are around their group mean. A larger standard deviation indicates more variability in the measurements, while a smaller one indicates that values lie closer to the mean. The standard deviation is not the same as the uncertainty in the estimated mean. That uncertainty also depends on the amount of information available and the design and analysis. The registry record states that standard deviation was the planned dispersion measure, but it does not report its value for either group.

Why is a group contrast different from a group mean?

In general, a group mean describes one group at a time, whereas a contrast expresses the difference between groups under a defined analysis. A contrast can be estimated with uncertainty, commonly expressed by a confidence interval. The interval indicates a range of values compatible with the data and analysis assumptions; it is not a guarantee that the true value lies within the interval. The registry record does not report group means, a contrast, or a confidence interval, so no numerical interpretation of a difference is possible.

Because allocation is not stated and the study is not described as randomized, a contrast between implant recipients and normal-knee participants should not automatically be interpreted as a causal treatment effect. In general, nonrandomized groups can differ for reasons related to participant selection, clinical history, or other characteristics. A statistical adjustment can sometimes address measured differences, but it cannot necessarily remove differences that were not measured or modeled. The registry record does not report adjusted analyses, covariates, or a statistical plan.

What role does a p-value play?

In general, a p-value assesses how compatible observed data are with a specified statistical model under a null hypothesis. It does not measure the size or clinical importance of a difference, and it does not give the probability that the null hypothesis is true. A p-value is most informative when read alongside the estimated effect, its uncertainty, and the analysis plan. No p-value or hypothesis test result is reported in the registry record.

Why might variability matter?

In general, biological measurements can vary between participants, and measurement procedures can add further variability. When measurements vary more than a simple statistical model allows, over-dispersion can make conventional uncertainty estimates too optimistic. Over-dispersion is especially familiar in count-data models, but the broader lesson is that the assumed variability should fit the data and design. The registry record does not describe a model, report a dispersion assessment, or provide data with which to assess whether a variance assumption was appropriate. No claim about over-dispersion in this study can therefore be made.

How should planning illustrations be read?

The registry record’s stated planning assumptions describe illustrations based on a fraction of an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The record says these illustrations are not the trial’s own design. For non-time-to-event outcomes, the described quantity is participants per arm for a target power; time-to-event calculations are described in terms of total events. These are planning concepts, not observed trial results and not observed power.

In general, a sample-size illustration estimates how much information might be needed under specified assumptions about an effect, variability, allocation, and statistical test. It does not demonstrate that an existing study had adequate power, and it cannot substitute for reporting the observed estimate and its uncertainty. The registry entries available for this analysis do not include the numerical sample-size illustration outputs or the observed primary effect required to interpret them. No planning value or achieved power should therefore be inferred.

The registry record does not describe how the two condyle measurements were handled statistically, whether there were repeated measurements, how missing observations were treated, or whether the outcome was adjusted for participant characteristics. Those choices can affect estimates and their uncertainty. In general, a transparent analysis specifies the outcome definition, analysis population, model, assumptions, missing-data approach, and planned comparisons before results are interpreted. Those details are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists eight outcome measures, while the primary outcome is described as translations of the medial and lateral femoral condyles during a deep knee bend. It does not report a statistical analysis plan explaining how outcomes or comparisons were prioritized. The record also does not say whether the two condyle measurements were treated as separate tests, whether other outcomes were exploratory, or whether any adjustment for multiple comparisons was planned. These details are not reported in the registry record.

In general, testing many outcomes or contrasts can increase the chance of obtaining at least one apparently noteworthy result by chance. Multiplicity procedures can control error rates, but the appropriate approach depends on the planned questions and analysis hierarchy. Without a prespecified hierarchy or reported multiplicity strategy, readers cannot determine how a collection of tests was interpreted. In this case, the absence of reported outcome estimates and analysis results means there is no set of findings on which to evaluate multiplicity adjustments.

Missing-data handling is also not described. The registry record does not state how many participants contributed primary outcome measurements, whether any measurements were unavailable, why they might have been unavailable, or whether an imputation or other method was used. It does not describe a sensitivity analysis for missing observations. In general, missingness can affect both the estimated group result and its uncertainty, particularly if the likelihood of missing data is related to participant characteristics or outcomes.

The analysis population is not identified. The record does not say whether the primary analysis included all enrolled participants, only participants with usable measurements, or another defined group. It also does not report exclusions or the handling of protocol deviations. Without these details, the population represented by any potential outcome estimate cannot be assessed. The registry record lists no analysis entries, so no analysis population or missing-data method can be verified from reported results.

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 registry record lists the serious and other adverse-event counts separately for the Journey II BCS TKA group and the normal-knee group. For each listed group, the recorded counts are zero serious adverse events and zero other adverse events. The participants at risk are given as 40 for the device group and 10 for the normal-knee group. These are the registry’s recorded figures for the safety categories; they should not be read as an independently confirmed absence of all harms.

In general, a zero event count is a description of what was recorded, not proof that the underlying risk is zero. Interpretation depends on how events were defined, collected, and followed over time, as well as on the amount of observation. The registry record does not report additional details about safety surveillance, event definitions, or the observation period for these counts. The listed groups are also not a randomized treatment comparison, so the counts do not establish a comparative safety effect.

Death counts are recorded as null rather than as zero. A null value means that a numerical count is not reported in the record; it should not be rewritten as a confirmed absence of deaths. The safety figures do not provide enough information to characterize event timing, severity beyond the listed categories, or attribution. They should be interpreted narrowly as the adverse-event counts and at-risk figures recorded for the two groups.

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

The study is framed around whether knee movement after Journey II BCS implantation resembles movement in people with a normal knee. Its primary outcome concerns anterior-posterior translations of the medial and lateral femoral condyles during a deep knee bend, measured 3 months post-operative. This describes the intended measurement and the clinical question, not an answer to it.

The registry record does not report numerical primary outcome results, estimates of group differences, confidence intervals, or p-values. It therefore does not show how much the measured translations differed between the listed groups, in which direction they differed, or how precisely any difference was estimated. The completed status and study dates do not fill that reporting gap.

The normal-knee group is not described as a randomized control group, and allocation is not stated. Comparisons between people with an implant and people with healthy knees may reflect differences between the groups beyond the device. The record does not report participant characteristics or adjusted analyses that could clarify the role of such differences. The study objective also mentions a historical comparison with recipients of a first-generation Journey PS TKA, but that group is not listed as a study arm and no comparative results are reported.

The background summary refers to observations from prior research, including more normal-like patterns and changes in rotation and weight-bearing knee flexion with the earlier design. Those statements do not establish what was observed in the present study of the revised device. The present registry record does not report a result for weight-bearing knee flexion or a comparison with the earlier cohort.

Accordingly, the record can be used to understand the intended kinematic assessment and the groups named in the study. It cannot establish whether the revised implant produced more normal-like movement, whether any observed difference was meaningful, or whether the device changed clinical function. Those conclusions require reported outcome data and an analysis whose methods and uncertainty can be evaluated.

13. Why This Trial Matters Statistically

This study raises a useful statistical distinction between describing movement and establishing a comparative effect. A continuous kinematic measurement can be summarized by a mean and standard deviation, but those summaries alone do not answer whether groups differ or how uncertain that difference is. The registry record identifies the measurement and its unit, yet does not report the numerical findings needed to evaluate the comparison.

The study also illustrates the importance of the comparator. A normal-knee group can provide a reference for movement patterns, but it is not automatically interchangeable with a group of people who have received an implant. Because allocation is not stated and the record does not describe a randomized comparison, differences between groups cannot be attributed to the device without careful consideration of design and participant characteristics. The objective’s reference to a prior-study cohort adds a further distinction: a historical comparison is not the same as a concurrent randomized control.

Outcome definition and analysis transparency matter as well. The primary endpoint refers to both medial and lateral condyle translations, and the record lists eight outcome measures. Without a reported analysis plan, readers cannot determine how multiple measurements and outcomes were prioritized, how missing data were handled, or what population was analyzed. These are not minor technical details; they shape the interpretation of estimates and their uncertainty.

Finally, the registry entry demonstrates why completion status is not equivalent to a complete results record. The study is marked completed, but no analysis entries or primary outcome values are listed. Statistical conclusions require results that can be examined, including effect estimates and uncertainty, not simply an objective and an outcome definition. In this case, the most defensible reading is that the study question is clear enough to describe, while its answer is not reported in the registry record.

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 primary limitation for interpretation is that the registry record does not report the primary outcome values or an analysis comparing the groups. Without means, standard deviations, effect estimates, confidence intervals, or p-values, the observed kinematic patterns cannot be characterized quantitatively. The record lists zero analysis entries, so no statistical result can be checked against the stated objective.

The comparison is not described as randomized, and allocation is not stated. The device group and normal-knee group are different by their defining clinical status, so they should not be treated as equivalent groups apart from implant exposure. Participant characteristics and methods for addressing potential confounding are not reported in the registry record.

The study objective refers to comparison with a first-generation Journey PS TKA group analyzed in a previous study, but that group is not listed as an arm in this record. Details needed to assess comparability between a current cohort and a historical cohort are not reported. The brief summary’s description of earlier findings should not be substituted for current results.

The primary endpoint description names medial and lateral condyle translations, but does not clarify how the two measurements were analyzed or how the eight listed outcomes were prioritized. The registry record does not report a multiplicity strategy, missing-data approach, analysis population, measurement protocol, or statistical analysis plan. It also does not provide participant characteristics or detail on the follow-up supporting the listed safety counts. These omissions limit assessment of bias, precision, and generalizability, even though the study is marked completed.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Optimized Loading Response by JOURNEY II BCS Knee Increases Daily Physical Activity and Functions — NCT02335710.
• Registry record last updated 2019-10-21; status last verified 2019-10.
• Results first posted 2016-08-26.
• 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

The registry record describes a completed study of in vivo knee kinematics after Journey II BCS total knee arthroplasty, with a normal-knee group as comparator. The stated primary outcome is mean anterior-posterior translation of the medial and lateral femoral condyles during a deep knee bend, in mm, at 3 months post-operative, with standard deviation as the dispersion measure.

The study objective also refers to comparison with a first-generation Journey PS group from a previous study, but that group is not listed as a study arm. Allocation is not stated, and the record does not describe a randomized comparison. Although eight outcome measures are listed, the primary values and analysis results are not reported in the registry record. The record therefore establishes the study question and intended measurement, but not the findings or their precision.