Clinical and Radiological Evaluation of Patients With DDD Following TLIF With 3-D Printed Titanium Cage: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical and Radiological Evaluation of Patients With DDD Following TLIF With 3-D Printed Titanium Cage (NCT03018392), a na na study. The primary outcome is Fusion Rate.

2. Clinical Question

The registry record describes a study of patients with degenerative disc disease undergoing transforaminal lumbar interbody fusion (TLIF) with the Stryker Tritanium Spinal System and pedicle screw fixation. Its stated purpose is to evaluate fusion rate and clinical outcomes at 1 year. The primary endpoint is fusion status at that time, classified as fused, progressing, or pseudoarthrosis.

This is a descriptive question about outcomes among participants receiving the procedure and device, not a randomized estimate of the difference between treatments. Without a control group, the registry record cannot establish how the observed outcomes compare with outcomes under another procedure, device, or course of care. The planned evaluation also includes clinical outcomes, but their definitions and results are not reported in the registry record. Consequently, the stated aim is broader than the primary endpoint information available in the record.

3. Trial Design

This is a completed, single-group, post-market outcomes study sponsored by Bone and Joint Clinic of Baton Rouge. The record lists enrollment of 20 and identifies the intervention as the Stryker Tritanium Spinal System. The arm description specifies TLIF with a Tritanium PL cage and pedicle screw fixation. The study is described as on-label and intended to add to long-term evidence for the device.

The registry record lists the start as 2017-01 and primary completion as 2020-01-28. It records the study status as completed. The phase is listed as NA. Allocation is also listed as NA, and masking is recorded as none. A single-group design means that the described study follows participants receiving the intervention without a concurrent comparison arm in the record. The registry record therefore does not provide a randomized, like-for-like treatment comparison.

The stated purpose is to evaluate fusion rate and clinical outcomes at 1 year among patients undergoing TLIF. The primary outcome timeframe is 1 year, and the endpoint description gives three categories of fusion status: fused, progressing, and pseudoarthrosis. The registry record lists one outcome measure and no analyses. The outcome counts, the approach to any clinical outcomes beyond the primary endpoint, and the statistical analysis plan are not reported in the registry record.

The design can describe outcomes in the enrolled group if those outcome data are reported, but this record does not report the primary endpoint results. It also does not report a protocol-level sample-size justification, eligibility details, follow-up completeness, or reasons for any missing measurements. Those omissions limit assessment of how the enrolled group was selected and how fully it represents the intended patient population.

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 Fusion Rate, measured over 1 year.

The primary endpoint is fusion rate at 1 year, measured as a count of participants and described using fusion status after surgery. The registry record defines the categories as fused, progressing, or pseudoarthrosis, with fused identified as the best outcome and pseudoarthrosis as failed fusion. No counts in these categories are reported in the registry record, so the endpoint’s observed distribution cannot be described from this record.

Fusion status is used as a structural outcome relevant to the stated aim of evaluating fusion after TLIF. The categories distinguish a recorded fused status from a status still progressing and from pseudoarthrosis. These categories are not interchangeable: combining them would require a prespecified definition of success, and no such composite definition is reported in the registry record. The endpoint description also does not state the imaging criteria, adjudication process, or rules for classifying uncertain or unavailable assessments.

In general, a binary endpoint has two possible states, while this endpoint description names three fusion-status categories. The registry record’s outcome is characterized as a participant count, but it does not give category counts or explain any recoding used for analysis. It therefore is not possible to infer whether results were analyzed as a multi-category outcome, as a binary success outcome, or in another way. The endpoint is clinically interpretable in concept, but the available record lacks the data and operational details needed to judge the result or its precision.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a participant-count outcome and a single-group design, but it does not report an analysis of the primary endpoint. The following statistical explanations are general. They clarify what common methods would mean without implying that the study used them.

What does a participant count describe?

A count describes how many participants fall into a defined outcome category. For a fusion endpoint, a report might give the number classified as fused, progressing, or pseudoarthrosis. To interpret such counts, readers need to know the denominator: whether it is all enrolled participants, those who completed follow-up, or those with an assessable endpoint. The registry record reports enrollment of 20 but does not report category counts, the number assessed, or the denominator used in an analysis.

A count alone is not a rate. A rate or proportion relates a numerator to a defined denominator. General statistical interpretation also distinguishes a participant-level outcome from repeated observations on the same participant; treating repeated observations as independent can understate uncertainty. The registry record describes fusion status at 1 year as a participant outcome and does not report repeated assessments or their analysis.

How would uncertainty be described?

In general, an estimate based on a sample is subject to sampling variability. A confidence interval gives a range of values compatible with the data under the statistical model and its assumptions. The interval’s width reflects precision, while the estimate’s relevance also depends on how participants were selected, how outcomes were measured, and whether missing observations could bias the result. No estimate or confidence interval for fusion status is reported in the registry record.

A p-value, when used, measures how incompatible the observed data are with a specified null model, under that model’s assumptions. It does not measure the probability that a treatment works, nor does it communicate the size or practical importance of an effect. The registry record lists no analyses and reports no p-value for the primary endpoint. A statistical test would also need a clearly stated question and analysis method, neither of which is reported for this outcome.

Why does the design matter for inference?

In general, random allocation can help balance measured and unmeasured prognostic factors between treatment groups, subject to chance variation and trial conduct. This record lists allocation as NA and describes a single group, so it does not provide a randomized comparison. A descriptive outcome in one group cannot separate the intervention’s contribution from other influences on the outcome. Comparisons with external benchmarks would require careful attention to differences in patient eligibility, care, outcome definitions, and follow-up; no such comparison is reported in the registry record.

Masking is recorded as none. In general, lack of masking can affect outcome assessment when judgment is involved, and may influence participant or clinician behavior. Whether this affected fusion classification cannot be determined because the record does not describe imaging review, assessors, or adjudication. The record also does not state whether endpoint assessment was standardized or whether assessors were independent of treatment delivery.

What do the planning assumptions mean?

The registry record describes a planning illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not a reported design justification for this study. The study itself is recorded as single-group, and no primary endpoint analysis or observed effect is reported in the registry record. Therefore, the two-arm planning assumptions do not describe the design actually recorded and cannot be read as evidence of observed power.

In general, sample-size planning estimates how many observations may be needed for a specified analysis under chosen assumptions about variability, effect size, error rates, and allocation. It does not show that an observed result is true, and it does not repair a lack of a control group. Planning based on an observed effect can be especially uncertain because that effect may itself be imprecise. For this study, no protocol sample-size justification is reported in the registry record. The enrollment of 20 should not be mistaken for evidence that the study was adequately powered for its stated aims.

Over-dispersion is a general concern when count data vary more than an assumed statistical model allows. If ignored, standard errors may be too small and confidence intervals too narrow. Its relevance depends on the outcome structure and analysis model. The registry record does not describe an analysis model for the fusion categories, so it is not possible to determine whether over-dispersion was considered or whether it was relevant to the chosen analysis.

Overall, the available statistical information supports description of the study design and endpoint definition, not a reconstruction of the analysis. The analysis population, missing-data approach, model, estimates, uncertainty intervals, and inferential results are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and no analyses. It does not report a statistical analysis plan, identify secondary endpoints in sufficient detail, or state whether any multiplicity adjustment was planned. Multiplicity arises in general when several outcomes, time points, subgroups, or statistical tests are considered. Repeated testing can increase the chance of a seemingly notable finding arising by chance. Adjustment methods and interpretation depend on the analysis objectives; the record does not establish whether any such methods were used.

The study purpose mentions fusion rate and clinical outcomes at 1 year, while the registered primary outcome measure is Fusion Rate. Definitions and results for additional clinical outcomes are not reported in the registry record. The record does not state whether the endpoint categories were analyzed separately, combined, or tested in a particular order. It is therefore not possible to assess the scope of testing or how a primary finding would have been distinguished from exploratory findings.

Missing-data information is also not reported in the registry record. The number enrolled does not establish how many had an evaluable 1-year fusion assessment. There is no reported follow-up denominator, description of missing observations, reason for missingness, or method for handling unavailable endpoint values. In general, missingness can affect a result when the chance that an outcome is missing is related to the outcome or to participant characteristics. Complete-case analysis, imputation, and sensitivity analyses each rely on assumptions and should be described rather than inferred.

The analysis population is not reported in the registry record. It is therefore unclear which participants, if any, were included in endpoint analyses, and how participants with incomplete follow-up or protocol deviations were treated. No subgroup analyses or interim analyses are reported. Their presence or absence cannot be established beyond what the registry record states; the statistical plan and related details are not reported in the registry record.

11. 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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: extension of fusion (5.0%).

The registry record reports safety counts for the Tritanium group. It lists 20 participants at risk and 1 with a serious adverse event, and 20 at risk and 1 with another adverse event. It records 0 deaths. The registry also lists “Extension of fusion” among the top serious adverse event terms at 5.0%. These figures describe the entries in the record; they do not provide event narratives, timing, severity grading, or information about relatedness to the device or procedure.

The meaning of the adverse-event categories and the relationship between the group-level counts and the listed event term are not explained in the registry record. A count of participants with an event is not necessarily the same as a count of events, since one participant may experience more than one event. The record does not clarify whether each participant was counted once per category, whether events overlapped, or how the percentage for the listed term was calculated.

In general, safety counts are interpreted in relation to the population monitored, follow-up duration, event definitions, and completeness of reporting. The registry record does not state how long participants were followed for safety, beyond the primary endpoint’s 1-year timeframe. The single-group design also offers no concurrent comparison for interpreting event frequencies. These counts should therefore be read as reported safety information, not as a comparative estimate or a determination of causation.

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

The registry record establishes that a completed, single-group post-market study enrolled 20 participants undergoing TLIF with the Stryker Tritanium Spinal System. It identifies fusion status at 1 year as the primary endpoint and describes the categories used to characterize that status. It also reports limited safety counts. These are details about the study record and its stated design.

The record does not report the primary endpoint result. There are no counts for fused, progressing, or pseudoarthrosis, no estimate of fusion rate, and no confidence interval. The clinical outcomes mentioned in the study purpose are not reported as results. It is not possible from the registry record to say what outcome pattern was observed, how precise an estimate might be, or whether all enrolled participants contributed an assessment.

Even if a single-group outcome estimate were reported, it would describe outcomes among participants in that group rather than isolate the effect of the device or procedure. In general, an uncontrolled study cannot directly show what the same participants’ outcomes would have been under an alternative. Differences in patient characteristics, selection, follow-up, and other care can complicate comparisons across studies. This record does not report a concurrent comparator or an external comparison.

The registry describes the study as intended to build on long-term evidence, but the primary outcome timeframe is 1 year. The record does not establish longer-term results. Nor does enrollment alone demonstrate that the study was designed to estimate a particular effect with a specified precision; a protocol-level sample-size justification is not reported in the registry record. The planning assumptions mentioned for illustrations are not a substitute for that justification or for outcome results.

The most defensible conclusion is narrow: the registry records the study’s purpose, a 20-participant enrollment, a single-group design, and a defined 1-year fusion endpoint, but does not report the endpoint findings. No conclusion about comparative benefit, absence of benefit, or causal effect follows from the information recorded.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between an endpoint definition and an endpoint result. The registry record describes the construct of interest—fusion status at 1 year—and names categories for classifying it. But without counts in those categories, readers cannot calculate or evaluate the outcome estimate. An endpoint’s clinical relevance does not by itself establish that its result has been reported with enough detail for statistical interpretation.

The single-group structure is also important. A cohort can provide descriptive evidence about outcomes among participants receiving a procedure and device. Such evidence may help frame further questions, but it does not create the counterfactual needed for a direct treatment comparison. This limitation persists even if a descriptive outcome appears favorable or unfavorable, because the record contains no concurrent control group against which to interpret it.

Enrollment and precision should not be conflated. The record reports enrollment of 20, but no outcome denominator, estimate, or interval. In general, the precision of an estimate depends on the number of evaluable observations and the outcome distribution, among other factors. Without endpoint results and follow-up information, precision cannot be assessed. Nor can planning illustrations be treated as observed power or as evidence that the study’s design was adequate.

Finally, this record illustrates why transparent reporting of analysis populations, missing data, endpoint definitions, and statistical methods matters. Those details allow readers to understand which participants informed a result, how uncertainty was quantified, and which assumptions shaped the interpretation. In their absence, statistical conclusions must remain limited to the design and outcomes explicitly recorded.

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.

Several limitations specific to this study follow from the registry information. The design is recorded as single-group, with allocation listed as NA and masking as none. No concurrent control is described, so the record cannot support a like-for-like comparative estimate. The findings, if reported elsewhere, would require cautious interpretation as outcomes in the observed group rather than as a causal contrast.

The primary endpoint is described but its result is not reported in the registry record. No category counts, effect estimate, confidence interval, or statistical test are available. Although enrollment is listed as 20, the number with an assessable 1-year outcome and the analysis population are not reported. The registry record also does not report the approach to missing data, follow-up completeness, or reasons for missing assessments.

Further endpoint details are absent. The record does not report imaging criteria, the classification process, assessor roles, or rules for resolving uncertain status. The clinical outcomes referenced in the study purpose are not defined or reported as results. A protocol sample-size justification, statistical analysis plan, and any multiplicity strategy are not reported in the registry record. The record lists no analyses.

Safety information is limited to the recorded counts and a listed serious adverse event term. Event timing, duration of safety follow-up, severity, relatedness, and details of possible overlap are not reported in the registry record. These limitations do not establish that information was not collected; they mean that it is not available in the registry record for interpretation.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Clinical and Radiological Evaluation of Patients With DDD Following TLIF With 3-D Printed Titanium Cage — NCT03018392.
• Registry record last updated 2022-09-07; status last verified 2022-08.
• Results first posted 2022-09-07.
• 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

NCT03018392 is a completed, single-group, post-market outcomes study sponsored by Bone and Joint Clinic of Baton Rouge. It enrolled 20 participants with intervertebral disc disease undergoing TLIF with the Stryker Tritanium Spinal System and pedicle screw fixation. Allocation is listed as NA, masking as none, and the study phase as NA.

The primary endpoint is fusion status at 1 year, categorized as fused, progressing, or pseudoarthrosis. The registry record lists one outcome measure and no analyses, but does not report the primary endpoint results or clinical outcome findings. It records 1 participant with a serious adverse event, 1 with another adverse event, and 0 deaths among 20 at risk in each category; “Extension of fusion” is listed at 5.0% among top serious adverse event terms.

The record does not report the analysis population, missing-data approach, statistical analysis plan, or comparative results. Its single-group design supports no randomized comparison.