Functional Performance of the Journey Deuce Bicompartmental Versus the Genesis II Total Knee System: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Functional Performance of the Journey Deuce Bicompartmental Versus the Genesis II Total Knee System (NCT01140815), a randomized phase 4 study. The primary outcome is 2-Year Knee Society Score.

2. Clinical Question

The study was designed to assess safety and effectiveness at 4–6 weeks, 4 months, 1 year, and 2 years. Its stated hypothesis was that the Journey Deuce system would be as safe and effective as the Genesis II system at 2 years; the stated null hypothesis was that there would be no difference between groups. The posted primary outcome focuses on the 2-year Knee Society Score, while the registry also lists imaging, patient survey, and functional testing outcomes. The registry record does not report a more detailed population definition or explain how the broad study objectives were translated into prespecified statistical decision criteria. Accordingly, the central statistical question that can be assessed from the posted primary result is the size and precision of the observed difference in mean scores, rather than whether a defined equivalence or noninferiority criterion was met.

3. Trial Design

This was a prospective, randomized, parallel-group study at a single center, classified as Phase 4 in the registry. Masking was listed as none. The record reports enrollment of 50 participants, with 25 in each arm for the primary Knee Society Score result. One arm received total knee replacement using the Total Knee System; the other received the Journey Deuce Bicompartmental Knee System. The study status is completed. The listed start was 2007-09 and the primary completion was 2013-05.

Random allocation is a design feature intended to reduce systematic differences between groups at the point of assignment. It does not, by itself, guarantee balanced characteristics in a modest-sized study, nor does it address bias from missing outcomes or differences in follow-up. The record identifies the study as unmasked, so participants and study personnel were not reported as blinded. Whether outcome assessors were masked separately is not reported in the registry record.

The brief summary gives assessment time points of 4–6 weeks, 4 months, 1 year, and 2 years. The primary endpoint is the 2-year Knee Society Score. The registry lists 13 outcome measures and posts 9 secondary outcomes, including x-rays, patient surveys, and functional testing. It reports no analyses for the trial overall and lists no reported analyses for the secondary outcomes. Details such as the randomization method, allocation concealment, original sample-size justification, handling of missing observations, and prespecified statistical plan are not reported in the registry record. These omissions limit how fully the planned analysis can be compared with the posted summaries.

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: Patients with only unicondylar arthritis were excluded and underwent unicondylar arthroplasty. Patients with arthritis in the lateral compartment were excluded and underwent total knee arthroplasty.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Preoperative osteoarthritis of the knee in medial and patellofemoral joints. BMI less than or equal to 35, Age less than or equal to 65. No previous knee surgery.

6. Primary Endpoint

The registry lists the primary outcome as 2-Year Knee Society Score, measured over 2 years.

The primary endpoint is the mean Knee Society Score at 2 years. The registry describes the Knee Society Clinical Rating System as providing separate knee pain and patient functional assessment scores. The scale runs from 0 to 100, with higher values representing a better score. The endpoint is reported as a mean with a standard deviation in each group.

A continuous score retains information across its range, rather than reducing the result to a count of participants above or below a threshold. Comparing group means therefore gives a summary of how the average recorded score differed at the stated time point. The standard deviation describes how spread out individual scores were within each group; it is not the uncertainty around the group mean. Uncertainty in the mean difference is described by its confidence interval.

The score was selected as the primary outcome for the 2-year comparison, but the registry record does not report a clinically important difference or a decision threshold for interpreting score changes. It also does not report separate primary results for the pain and function components. The posted result should therefore be read as a comparison of the reported overall score means, not as evidence about each component considered separately. A mean score summarizes the group and does not indicate that every participant had a similar score or experience.

7. Results Posted in the Registry

• Deuce: mean 94.20 versus 91.30 on control; difference 2.90 (95% CI -1.46 to 7.26), standardized effect d = 0.37; z-test p = 0.192.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

1-year X-rays

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Deuce: 12.0% (3/25) versus 8.0% (2/25) on control; risk difference 4.0 percentage points (95% CI -12.6 to 20.6), risk ratio 1.50 (0.27–8.22); unadjusted two-proportion z-test p = 0.637.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Deuce and the control. The interval gives the range of effects that remain compatible with the data.

2-year X-rays

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Deuce: 16.0% (4/25) versus 24.0% (6/25) on control; risk difference -8.0 percentage points (95% CI -30.1 to 14.1), risk ratio 0.67 (0.21–2.08); unadjusted two-proportion z-test p = 0.480.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Deuce and the control. The interval gives the range of effects that remain compatible with the data.

6-week Functional Testing

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Deuce (Study): mean 35.10 versus 36.50 on control; difference -1.40 (95% CI -8.86 to 6.06), standardized effect d = -0.10; z-test p = 0.713.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Deuce (Study) and the control. The interval gives the range of effects that remain compatible with the data.

The registry posts secondary findings across imaging outcomes and functional testing, with the listed time points including 6 weeks, 4 months, 1 year, and 2 years. It also lists 2-year patient surveys. The posted secondary results are a subset of the registry’s 13 outcome measures; 9 secondary outcomes are posted. The registry record lists no reported analyses for these outcomes, so the arm summaries and unadjusted comparisons do not amount to a fully described secondary analysis plan.

Across the available results, the comparisons are imprecise: their confidence intervals include values on either side of no difference. The observed directions are not uniformly the same across measures and time points. That pattern is not inherently contradictory, because imaging counts, functional test times, and patient-reported measures capture different aspects of outcome and are measured on different scales. Nor does a mix of directions establish a consistent advantage for either group.

The secondary findings add descriptive context to the primary Knee Society Score result, but they do not replace it. A secondary result may suggest questions for further study, yet its weight depends on whether it was prespecified, how missing observations were handled, and whether multiple comparisons were considered. Those details are not reported in the registry record. Without them, the unadjusted secondary p-values should be treated cautiously rather than as independent confirmatory evidence.

In general, examining many endpoints and time points increases the opportunity for chance findings. A multiplicity strategy can control or otherwise address that issue, but no such strategy is reported. The secondary outcomes therefore provide a broad, exploratory view of posted measurements, not a set of definitive tests that can be interpreted in isolation. The totality of the registry results is best understood through the primary estimate and its precision, with secondary results considered as supplementary descriptions rather than as proof that the primary conclusion is confirmed or contradicted.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• 6-Week X-rays
• 4-month X-rays
• 1-year X-rays
• 2-year X-rays
• 2-year Patient Surveys
• 6-week Functional Testing
• 4-month Functional Testing
• 1-year Functional Testing

9. Statistical Interpretation

10. Statistical Methods Explained

The primary result is a comparison of means on a continuous outcome. The registry reports the mean and standard deviation for each arm, followed by a mean difference, confidence interval, and unadjusted p-value. The reported mean difference is Deuce minus Total, so a positive value indicates a higher observed mean in Deuce, consistent with the score’s stated direction in which higher values represent a better score.

What does the mean difference summarize?

In general, the mean is the arithmetic average of the measured scores in a group. A difference between two means expresses how far apart those group averages are in the units of the outcome. Here, the unit is the Knee Society Score, described on a 0–100 scale. A mean difference does not describe every participant’s outcome, and it does not show how much the score changed for each participant unless the analysis specifically uses within-participant changes. The registry reports the 2-year group means, not a change-from-baseline comparison.

The standard deviation is a measure of spread among observations within a group. It is distinct from a standard error, which concerns uncertainty in an estimate such as a mean. The registry record does not describe a baseline-adjusted model or other covariate adjustment for the primary result. The comparison and interval posted in the record are therefore best read as an unadjusted summary-level comparison, rather than as a result from a fully described adjusted analysis.

How should the p-value be read?

In general, a p-value measures how unusual data at least as discrepant as those observed would be under a specified null hypothesis and model. It is not a measure of clinical importance, and it is not the probability that the null hypothesis is true. The posted primary p-value is unadjusted. The registry record does not report the exact test, model diagnostics, or a complete statistical analysis plan, so interpretation should not assume analysis details that are absent from the record. The confidence interval is useful alongside the p-value because it displays a range of effect estimates compatible with the data under the interval procedure.

Why do the binary outcomes use different summaries?

For outcomes recorded as participant counts, such as the posted x-ray outcomes, the comparison is expressed as a risk difference. In general, a risk difference is the difference between the proportions experiencing an outcome in the two groups. Its units are absolute percentage-point differences when the underlying proportions are expressed as percentages, though the registry posts the estimate on the proportion scale. A confidence interval for a risk difference describes uncertainty in that absolute contrast. The record also contains ratio estimates for these outcomes, but the main comparisons are unadjusted and the registry does not list reported analyses for them.

Why can small studies have uncertain estimates?

In general, estimates become less precise when there is substantial variability or relatively little information. For a continuous endpoint, the standard deviation contributes to uncertainty in a group mean. For a binary endpoint, the number of observed events and the number of participants affect the precision of estimated proportions and their contrasts. This trial enrolled 50 participants overall, and the posted primary endpoint has 25 participants in each arm. Those group sizes and the observed variation are relevant context for the width of the primary confidence interval, but they do not determine whether the study was adequately designed for a particular target effect. Its original sample-size justification is not reported in the registry record.

Over-dispersion is a general concern when count or binary outcomes vary more than a simple statistical model expects. If present and not accounted for, it can make standard errors too small and intervals too narrow. The registry does not report a model-based secondary analysis or diagnostics that would allow over-dispersion to be assessed. The posted secondary outcomes should therefore not be read as though a particular over-dispersion correction was performed.

What does randomization contribute?

In general, random allocation aims to make treatment groups comparable with respect to measured and unmeasured factors at assignment. In a small study, chance imbalances can still occur. Randomization also does not prevent bias from incomplete outcome data, deviations from assigned treatment, or unmasked assessment. The registry identifies random allocation and no masking, but the method of sequence generation, concealment, adherence, and analysis population are not reported in the registry record. These are important distinctions when judging how strongly the arm comparison supports an interpretation about the intervention itself.

Overall, the posted statistics permit a direct description of the observed group means and their unadjusted contrast. They do not supply enough detail to reconstruct every aspect of the original analysis plan or to assess whether alternative models would yield the same inference.

11. Confidence Intervals and Precision

The primary mean difference is 2.9 units, with a 95% confidence interval from -1.457 to 7.257. The interval includes zero, as well as values on both sides of zero. Thus, the posted estimate does not tightly determine whether the underlying mean difference favors Total or Deuce. The point estimate alone gives a single best estimate from the observed summaries, while the interval makes the uncertainty around that estimate visible.

In general, a confidence interval is a range produced by a statistical procedure that, under its assumptions, reflects the uncertainty in an estimate. It is not a range containing a fixed proportion of individual participants’ scores, and it is not a probability statement about a particular treatment effect after the data have been observed. Its width is influenced by the amount of information and variability in the data, as well as the method used to construct it.

The observed standard deviations were 9.6 for Total and 5.6 for Deuce. These values describe the spread of participant scores within the groups and help explain why an average difference is not known with complete precision. The registry does not report an adjusted confidence interval, sensitivity analysis, or a prespecified threshold for a meaningful score difference. Without such context, the interval can show statistical uncertainty but cannot by itself distinguish clinically important values from values that are not important to patients or clinicians.

The interval should be considered together with the design and reporting limitations. The record does not report how missing primary outcomes were handled or which analysis population was used. If outcome availability or analysis choices affected the comparison, the displayed interval would not capture that source of uncertainty. The confidence interval quantifies sampling uncertainty under its method; it does not account for every possible bias or limitation in the conduct and reporting of the study.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are illustrations based on the observed effect, not the trial’s original design calculation. For continuous outcomes, they are stated as participants per arm. The assumptions listed for these illustrations are a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; the effect to detect is the stated fraction of the observed effect. The registry record does not report the assumptions behind the trial’s own original sample-size design.

The 80% power column gives the planned number of participants per arm for a hypothetical study with an 80% chance of detecting the specified effect under those assumptions, if that effect and the model assumptions were correct. The 90% power column uses a higher target chance of detecting that effect, and consequently requires more participants per arm in the displayed planning scenarios. These are prospective planning quantities, not descriptions of the chance that the completed trial detected an effect.

Rows for 100%, 75%, and 50% of the observed effect represent different assumed target effects. Smaller assumed effects need more participants to distinguish them from random variation at the same target power. For example, the primary-outcome illustration lists 116 participants per arm for 80% power when planning for 100% of the observed effect, and 462 participants per arm when planning for 50% of it. The large change illustrates how strongly sample-size requirements can depend on the effect selected for planning.

A planning curve of these figures is read as a visual representation of that relationship: as the target effect becomes smaller, the required sample size rises. The figures are not a recommendation for a future study and do not establish the appropriate effect size or clinically meaningful threshold. They are also not observed power: observed power is not a useful substitute for interpreting the estimate and its confidence interval after results are known.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 2.900; pooled standard deviation σ = 7.859.
2. n = 2 × (1.96 + 0.842)² × 7.859² / 2.900² = 115.3, rounded up to 116 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 2.90000000000001                      # observed difference in means
sigma <- 7.8587530817554                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1140815)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 116 (80% power), 155 (90% power)
 75% of observed effect: n per arm = 205 (80% power), 275 (90% power)
 50% of observed effect: n per arm = 462 (80% power), 618 (90% power)
power.t.test: 116.2 
Simulated power at n = 116 per arm: 0.799 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists 13 outcome measures, including a primary outcome and multiple secondary outcomes at different time points. It does not report a multiplicity adjustment or a hierarchy for testing the outcomes. This matters because, in general, conducting multiple statistical tests increases the chance that at least one result will appear unusual by chance, even when there is no true effect for any outcome. The extent and handling of that issue depend on the prespecified plan, which is not reported in the registry record.

The primary p-value is identified as unadjusted. The secondary outcomes also have unadjusted comparisons, and no analyses are listed for them. The record does not say whether some outcomes were intended to be descriptive, whether specific comparisons were designated as confirmatory, or whether the testing order was fixed in advance. Consequently, the posted p-values should not be interpreted as a family of results with a known overall error rate. This limitation does not change the reported estimates, but it affects how confidently isolated p-values can be used to make claims.

Missing-data procedures are also not reported in the registry record. Although the primary summary includes 25 participants per arm, the registry does not describe whether all randomized participants contributed an endpoint, whether any observations were missing, or how missing scores were handled. The analysis population is not reported. It is therefore not possible to determine from the record whether the primary comparison followed an intention-to-treat approach, a per-protocol approach, or another population definition.

The record does not provide details on imputation, sensitivity analyses, deviations from assigned treatment, or withdrawal patterns. These omissions matter because incomplete follow-up can affect the estimated group difference, particularly if missingness is related to outcomes or differs between groups. The registry also does not report a detailed statistical analysis plan or interim analysis procedures. None of these details should be inferred from randomization or from the final status of the study. The posted data remain interpretable as group summaries, but the missing reporting limits assessment of whether the analyses were prespecified and robust to alternative assumptions.

15. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: revision knee arthroplasty (12.0%).

The registry reports serious adverse events affecting 1 participant in the Total group and 3 participants in the Deuce group; each arm had 25 participants at risk in the serious-event summary. For other adverse events, the registry reports 3 affected participants in Total and 1 in Deuce, with 25 at risk in each group. These are counts of affected participants in the posted record, not a complete description of event timing, duration, severity, or relationship to the assigned system.

Revision knee arthroplasty is listed among the top serious adverse event terms, with 12.0% reported. The registry does not provide enough detail in this summary to establish how that term was distributed across arms or whether individual participants had more than one event. Death counts are not reported in the registry record.

These figures describe the adverse-event entries posted for the trial. With the small group sizes and limited event detail, the counts should not be read as precise comparative safety estimates. They also do not establish that an event was caused by a study system. The registry record does not report a detailed safety analysis or an adjusted comparison of adverse-event risk.

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

The primary result describes the 2-year mean Knee Society Score in the two randomized groups and the uncertainty around their observed difference. The mean was 91.3 in Total and 94.2 in Deuce, with a Deuce-minus-Total estimate of 2.9 and a 95% confidence interval from -1.457 to 7.257. This indicates that the data do not pin down the direction or size of the underlying mean difference with high precision. It does not show that the groups are identical.

The result does not establish equivalence or noninferiority. Although the study summary states a hypothesis of being “as safe and effective as,” the registry record does not report a prespecified equivalence or noninferiority margin or the analysis required to evaluate such a margin. A p-value above a conventional threshold is not evidence that clinically relevant differences have been ruled out. Nor can the confidence interval be judged against clinical importance without a meaningful-difference threshold, which is not reported in the registry record.

The findings also do not establish what happened to every participant. Group means compress individual variation, and the record does not post participant-level outcomes. The posted summaries do not explain missingness, adherence, or the analysis population. The unmasked design and the absence of reported analysis details are relevant when considering possible sources of bias.

Secondary findings broaden the description of the study but are not a substitute for a prespecified, multiplicity-aware analysis. Their unadjusted character and the absence of reported secondary analyses limit the strength of conclusions that can be drawn from them. Similarly, the adverse-event counts are descriptive and do not establish a causal safety difference.

In general, a trial result is most informative when its estimate, uncertainty, design, and analysis plan are considered together. For this record, the most defensible reading is that the posted primary estimate modestly favors the Deuce group in the observed scores, while its confidence interval remains compatible with differences in either direction. The registry result alone does not determine clinical importance, equivalence, or the comparative safety profile.

17. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between a point estimate and the precision of an estimate. The Deuce group had a higher observed mean Knee Society Score, and the mean difference was 2.9 units. Yet the confidence interval extends across zero and includes both negative and positive values. Reporting the point estimate without its interval could make the result appear more decisive than the posted data warrant.

The study also illustrates why a hypothesis framed as “as safe and effective as” requires more than a non-significant test of difference. Equivalence is a specific statistical question: the acceptable range of differences must be defined in advance, and the analysis must assess whether the interval lies within that range. The registry record does not report those elements. This distinction is important when interpreting randomized trials whose stated objectives use similarity language.

Another relevant feature is the relationship between sample size, effect size, and precision. The trial enrolled 50 participants, while the planning illustrations show that hypothetical sample requirements rise as the target effect is reduced. Those illustrations make clear that a study capable of estimating a large difference with a given degree of power may be less informative about smaller differences. They do not reveal the original design rationale, which is not reported in the registry record.

Finally, the record demonstrates how outcome breadth and incomplete analysis reporting affect interpretation. Multiple outcomes and time points can describe different dimensions of performance, but unadjusted secondary findings need cautious interpretation. Clear reporting of prespecified endpoints, missing-data methods, analysis populations, and multiplicity handling would make the evidence easier to evaluate. The posted summaries support careful description of the observed results, while leaving important questions about the planned and conducted analyses unanswered.

18. 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.

Several limitations specific to this record constrain interpretation. The trial was conducted at a single center, and the registry does not report participant eligibility criteria or baseline characteristics. It is therefore difficult to judge how closely the enrolled participants represent a broader population undergoing knee arthroplasty. The record reports no masking, and it does not clarify whether outcome assessors were masked. This is particularly relevant for outcomes that involve assessment or participant reporting.

The enrollment was 50, with 25 participants per arm in the primary outcome summary. The resulting primary confidence interval spans values in both directions. The registry does not report the original sample-size justification, the target effect, or a clinically meaningful score difference. The planning figures based on the observed effect cannot resolve those missing design details.

The record does not report the randomization sequence method or allocation concealment, the analysis population, or how missing outcomes were handled. It also lacks a detailed statistical analysis plan, multiplicity strategy, and reported analyses for the secondary outcomes. These gaps prevent a full assessment of adherence to prespecified methods and the robustness of results to alternative assumptions.

The posted adverse-event summary has limited detail, and death counts are not reported in the registry record. The summaries do not provide enough information to assess event timing, recurrence, or causal attribution. Finally, the registry’s stated objective of assessing safety and effectiveness across several time points is broader than the primary endpoint result alone. The available posted results should not be treated as a complete account of every planned outcome or analysis.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Functional Performance of the Journey Deuce Bicompartmental Versus the Genesis II Total Knee System — NCT01140815.
• Registry record last updated 2014-08-04; status last verified 2014-07.
• Results first posted 2014-08-04.
• 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.

22. Record Summary

NCT01140815 is a completed, prospective, randomized, single-center, parallel-group Phase 4 study comparing the Journey Deuce Bicompartmental Knee System with total knee replacement using the Total Knee System. The registry summary names the Genesis II Total Knee System as the comparator. Enrollment was 50, and the study was unmasked.

The primary outcome was the mean Knee Society Score at 2 years, on a 0–100 scale where higher scores represent a better score. The posted means were 91.3 for Total and 94.2 for Deuce. The mean difference was 2.9, with a 95% confidence interval from -1.457 to 7.257 and an unadjusted p-value of 0.192. The registry lists additional imaging, survey, and functional outcomes, but no reported analyses for the secondary outcomes.

The registry record does not report the original sample-size justification, detailed statistical plan, missing-data procedures, or analysis population. The primary estimate and its interval therefore support a descriptive comparison, while important aspects of the planned and conducted analyses remain unspecified.