A Post-Market Clinical Evaluation of the ReUnion TSA System: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Post-Market Clinical Evaluation of the ReUnion TSA System (NCT03858517), a registered phase not stated study. The primary outcome is American Shoulder and Elbow Surgeons (ASES) Shoulder Score.

2. Clinical Question

3. Trial Design

NCT03858517 is a prospective, multicenter post-market clinical evaluation of the ReUnion TSA System, sponsored by Stryker Trauma and Extremities. The registry lists the study start as 2019-06-25 and primary completion as 2022-07-08. Its status is recorded as terminated. The reason for termination is not reported in the registry record.

The investigation was designed around use of the device in shoulder arthroplasty. The brief description states that clinical evaluation would follow the surgeon's standard of care, with ongoing regular assessment or evaluation as needed if a subject became symptomatic in the treated joint. The registry does not provide a detailed schedule of visits, assessments, or follow-up procedures beyond the primary endpoint's 24-month timeframe.

The brief description anticipated enrollment of 100 subjects at approximately 4-7 sites. Actual enrollment is listed as 51. The record does not explain the difference between anticipated and recorded enrollment, and it does not state whether every enrolled subject received the device or completed follow-up.

The primary endpoint was the ASES Shoulder Score at 24 months post-operative, with an objective of demonstrating non-inferiority to selected literature controls. No concurrent control arm or randomized allocation is described. A direct treatment comparison within the registered study is therefore not available in the recorded design information. The non-inferiority margin and details of the literature-control data are not reported in the registry record.

Safety and implant survivorship were also identified as secondary outcomes. Safety was to be assessed by capturing incidence of device-related intra-operative and post-operative adverse events. Efficacy was to be monitored through implant survivorship among subjects with a total or partial prosthesis. The registry lists three outcome measures, but it does not provide corresponding detailed results for these secondary outcomes.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The Total ASES Shoulder Score (1 \& 2 year LOCF) was available for 24 subjects

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 American Shoulder and Elbow Surgeons (ASES) Shoulder Score, measured over 24 months.

The primary endpoint is the American Shoulder and Elbow Surgeons (ASES) Shoulder Score, a score on a scale from 0 to 100. The registry states that 0 indicates a worse shoulder condition and 100 indicates a better shoulder condition. This makes the score a measure of shoulder status in which higher values represent a better reported condition.

The endpoint timeframe is 24 months after surgery. The registry identifies the mean as the summary measure and standard deviation as the dispersion measure. These statistics can describe the average score and the spread of scores among participants, but the record does not report the observed mean or standard deviation.

The score was selected as the measure for the stated non-inferiority objective against selected literature controls. In general, a patient-related clinical score can express status in a form that is comparable across participants, while the specified follow-up time identifies when the primary assessment is intended to occur. The registry does not report the non-inferiority margin or explain the choice of that margin.

The endpoint population is described as 24 subjects with Total ASES Shoulder Score data using 1- and 2-year last-observation-carried-forward information. The record does not give the endpoint estimate, its uncertainty, or a statistical conclusion. Consequently, the stated endpoint and direction of scoring are known, but the primary outcome result is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

The registry identifies the mean as the primary endpoint summary and the standard deviation as its dispersion measure. In general, the mean describes the central average of a set of scores. The standard deviation describes how widely individual scores tend to vary around that average. Together, they can characterize the score distribution, but they do not show every participant's result or explain why participants differ.

For this investigation, the ASES Shoulder Score ranges from 0 to 100, and higher values indicate a better shoulder condition. The registry does not report the mean or standard deviation. Their designation in the endpoint description identifies the intended form of summary, not a result that can be interpreted from the available entry.

What is a non-inferiority comparison?

In general, a non-inferiority study asks whether an intervention is not worse than a comparator by more than a prespecified amount considered acceptable for the study question. The margin is central to that interpretation: it defines the boundary against which the estimated difference and its uncertainty are judged. A non-inferiority objective is not established simply because a conventional test fails to find a difference.

The registry states that the device was to be compared with selected literature controls using the ASES Shoulder Score at 24 months. The margin, comparator data, analysis specification, effect estimate, and confidence interval are not reported in the registry record. The objective is recorded, but its statistical evaluation cannot be reconstructed from the entry.

Why does the confidence interval matter?

In general, a confidence interval expresses the uncertainty around an estimated effect. A narrow interval indicates greater precision than a wide interval, while the interval's position relative to a clinically or statistically defined boundary informs interpretation. For a non-inferiority question, the interval must be considered in relation to the margin and the direction in which worse outcomes are defined.

No confidence interval for the primary endpoint is reported. The registry also gives no primary effect estimate to which an interval could be attached. As a result, neither the magnitude nor precision of the planned comparison is available for statistical interpretation.

What do planning assumptions mean?

The registry's planning illustration is described as using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also describes the effect to detect as a stated fraction of the observed effect. These are assumptions for a planning calculation, not evidence about the observed study outcome. The registry record does not report the resulting planning values or a sample-size justification for the trial's own design.

In general, planning calculations estimate the number of participants needed under chosen assumptions about an effect, variability, significance level, and allocation. They are not a measure of the probability that a completed study found a real effect. Sample-size illustrations should not be read as observed power. In particular, a calculation based on an observed effect is not a substitute for the uncertainty interval around the estimate, and its result depends on the assumptions used.

Why does over-dispersion matter?

In general, over-dispersion means that observed variability is greater than a statistical model expects. When a model assumes less variability than the data contain, uncertainty can be understated and inference can appear more precise than it is. For a continuous score, the reported standard deviation is one way to describe variation, although a single summary does not establish whether a model's assumptions are appropriate.

The registry identifies a continuous endpoint summarized by a mean and standard deviation, but it does not provide the observed dispersion or details of the analysis model. There is therefore no basis in the registry entry to assess over-dispersion or the adequacy of any model used for the primary comparison.

What can be inferred from the listed analysis information?

The registry lists no statistical analyses. It does not report a model, adjustment variables, handling of repeated observations, confidence-interval method, or sensitivity analysis. These omissions do not establish that no analysis was conducted; they mean the analyses are not reported in the registry record. A reader cannot infer the exact statistical plan or reproduce the primary comparison from the registry entry alone.

The planned comparison with literature controls also requires information about how those external data were selected and made comparable. In general, an external comparison may be sensitive to differences in populations, outcome collection, follow-up, and background care. Those are methodological considerations rather than findings about this investigation. The relevant details are not reported in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("ReUnion TSA System")
n   <- c(24)
m   <- c(78.75)
sp  <- c(26.19)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  ReUnion TSA System  24  78.750  26.190  67.691  89.809

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary ASES Shoulder Score endpoint and identifies safety and implant survivorship as secondary outcome areas. The study description also lists three outcome measures. However, the registry does not provide a statistical analysis plan explaining which outcomes were confirmatory, how multiple outcomes were handled, or whether any hierarchy or adjustment was planned. Multiplicity handling is not reported in the registry record.

Multiple statistical tests can increase the chance of an apparently notable result when many outcomes or comparisons are assessed. In general, a prespecified strategy helps distinguish a primary analysis from exploratory analyses and clarifies how evidence across outcomes should be interpreted. The record does not report whether such a strategy was used, nor does it report interim analyses.

The primary endpoint population is described as 24 subjects with a Total ASES Shoulder Score using 1- and 2-year last-observation-carried-forward data. Last observation carried forward is, in general, an approach that uses a participant's previously observed score in place of a missing later score. Its validity depends on assumptions about how scores change after the last observation. The registry does not report the detailed imputation rules, the number or timing of missing scores, or sensitivity analyses that might examine alternative assumptions.

The record does not define the analysis population for the primary endpoint beyond the stated 24 subjects. It does not report whether all enrolled subjects, only treated subjects, or another defined group was intended for the non-inferiority analysis. It also does not report how withdrawals or incomplete follow-up were handled. These details matter because analysis-population choices can affect non-inferiority interpretation. No specific missing-data or population-analysis plan is reported in the registry record.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

Most frequent non-serious adverse event terms

The registry's safety summary lists 51 subjects at risk in the ReUnion TSA System group for the serious-event category and 0 affected. It lists 51 at risk for the other-event category and 5 affected. The death count is 0. These are the counts recorded for the group; the entry does not provide event-level descriptions or a statistical comparison.

The secondary-outcome description says safety was to be assessed by capturing device-related intra-operative and post-operative adverse events. The safety summary does not identify the five other events by type, timing, severity, or relationship to the device. It also does not list serious-event terms. The absence of listed serious terms should not be interpreted as a detailed account of all events, since event descriptions are not reported in the registry record.

In general, a count is descriptive and does not by itself establish the risk of an event in other settings or support a comparison with another treatment. The record does not provide follow-up duration for each subject or explain how safety data were collected after discontinuation. These figures should therefore be read as registry-reported counts, not as a complete characterization of safety.

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

The record establishes that the investigation was intended to evaluate the ReUnion TSA System after market authorization, using a prospective, multicenter design and a non-inferiority objective based on the ASES Shoulder Score at 24 months. It records enrollment of 51 and identifies 24 subjects as having a Total ASES Shoulder Score using 1- and 2-year last-observation-carried-forward data. It also provides limited safety counts.

Those details do not establish the result of the primary question. No score estimate, comparison with literature controls, confidence interval, p-value, or non-inferiority margin is reported in the registry record. The record therefore does not show whether the planned non-inferiority criterion was met, how large any difference was, or how precisely an effect was estimated. No medical conclusion should be drawn from the missing primary result.

The device was the only intervention listed, and the registry does not describe a randomized concurrent comparator. The planned literature-control comparison cannot be evaluated without information about the external data and the statistical comparison. General differences between study and literature populations can affect an external comparison, but the registry does not report enough detail to determine whether or how this concern was addressed.

The termination status is recorded, but its reason is not reported. The entry does not explain the enrollment shortfall relative to the anticipated total, the status of follow-up, or the reasons the endpoint population is limited to the stated group. The safety counts are also limited by the absence of event descriptions and follow-up detail.

In general, a registry entry documents what was registered and what results were posted to that record; it may not contain every analysis or study document. For this investigation, the available record supports a description of the design and the reported counts, but it does not support a conclusion about the primary endpoint or the study's stated non-inferiority objective.

14. Why This Trial Matters Statistically

This investigation raises several statistical issues that are important in post-market device evaluations. Its stated question was non-inferiority against selected literature controls, yet the registry entry does not report a non-inferiority margin or the comparison result. Because the margin defines the boundary for the claim, its absence prevents a reader from assessing how the planned criterion was meant to operate.

The comparator is also consequential. The registry describes no randomized concurrent control group and identifies literature controls instead. In general, external comparisons can be useful, but their interpretation depends on whether populations, outcome definitions, follow-up, and data collection are sufficiently comparable. The registry record does not report the details needed to assess those features.

Endpoint availability is another key consideration. Enrollment is recorded as 51, while the primary-endpoint population is described as 24 subjects with last-observation-carried-forward data. Without a detailed account of missing outcomes, participant follow-up, and imputation assumptions, the potential influence of missing data cannot be assessed. This is especially relevant when the endpoint is intended to support a non-inferiority conclusion, because missing information can affect the apparent similarity between groups.

The record also illustrates why a study objective, a planning illustration, and an observed result are different things. The registry identifies a planned statistical objective and assumptions for a planning calculation, but it lists no statistical analyses and no primary outcome estimate. Planning assumptions cannot replace reported estimates and their uncertainty. The posted information therefore serves mainly to identify the intended question and the limits of the available statistical evidence.

15. 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 central limitation for statistical interpretation is that the primary endpoint result is not reported in the registry record. The ASES Shoulder Score measure, scoring direction, summary type, and timeframe are described, but no mean, standard deviation, comparison estimate, confidence interval, or test result is available. The non-inferiority margin is also not reported, so the main objective cannot be evaluated.

The registry lists enrollment of 51 and an anticipated enrollment of 100, but does not explain the difference. It identifies 24 subjects with endpoint data using 1- and 2-year last-observation-carried-forward information, without describing missingness, follow-up completion, or the reasons data were unavailable for other enrolled subjects. The exact analysis population and sensitivity analyses are not reported.

The comparator information is limited. The stated objective refers to selected literature controls, but the registry does not identify the control data or explain how comparability was assessed. No concurrent randomized control group is described. Statistical methods, adjustment procedures, multiplicity handling, interim analyses, and the reason for termination are not reported in the registry record.

Safety information is also sparse. The record gives affected counts and numbers at risk, but does not describe the five other events or provide event timing, severity, or follow-up detail. These limits mean the posted information supports a narrow description of study conduct and recorded counts, rather than a full evaluation of effectiveness or safety.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Post-Market Clinical Evaluation of the ReUnion TSA System — NCT03858517.
• Registry record last updated 2025-01-31; status last verified 2025-01.
• Results first posted 2025-01-31.
• 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.

19. Record Summary

NCT03858517 is a prospective, multicenter post-market clinical evaluation of the ReUnion TSA System for shoulder arthroplasty. The sponsor is Stryker Trauma and Extremities. The registry lists a start date of 2019-06-25, primary completion on 2022-07-08, status as terminated, and enrollment of 51. The brief description anticipated enrollment of 100 subjects at approximately 4-7 sites.

The primary endpoint was the mean ASES Shoulder Score at 24 months, with the stated objective of non-inferiority to selected literature controls. The registry describes 24 subjects with Total ASES Shoulder Score data using 1- and 2-year last-observation-carried-forward information. No primary score result or statistical analysis is reported.

The safety summary records 0 serious events, 5 other events, and 0 deaths, with 51 subjects at risk for each adverse-event category. Event descriptions, the reason for termination, and detailed analysis methods are not reported in the registry record.