Suture Anchor Comparison in Rotator Cuff Repairs: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Suture Anchor Comparison in Rotator Cuff Repairs (NCT02350647), a randomized na study. The primary outcome is Ossification Quality Score (Bony Ingrowth Assessed Via CT).

2. Clinical Question

The registry hypothesis anticipated high-quality ossification in 85% of HEALICOIL REGENESORB anchors and 49.9% of TWINFIX Ultra HA anchors at 24 months. Those values describe the stated hypothesis, not observed results. The intended clinical and radiological assessments also included questionnaires and imaging, with ultrasound used to assess rotator cuff repair success. The registry lists re-tear, pain, shoulder function and quality-of-life outcomes as secondary outcomes. The central statistical issue is that the primary endpoint is measured per anchor, whereas assignment and clinical experience occur at the participant level. Since some participants could contribute multiple anchors, anchor observations within a participant may be related. The record does not report how that relationship was addressed in the analysis.

3. Trial Design

The registry describes a randomized, parallel-group study comparing HEALICOIL REGENESORB with TWINFIX Ultra HA in rotator cuff repair. The study status is completed, and enrollment is recorded as 64. The recorded start and primary completion dates are 2014-05 and 2019-03. The phase is listed as not applicable. These design and enrollment details describe the registered study; they do not establish how many participants were included in any particular outcome analysis.

The masking descriptions do not align perfectly: the structured masking field records double masking, while the official title calls the study single blind. The registry record does not explain this difference or state which people were masked. The allocation is recorded as randomized, but the sequence-generation method, concealment procedure and implementation details are not reported in the registry record. The record also does not report the planned allocation ratio.

The study compared two suture anchor devices, with both arms described as receiving an anchor for rotator cuff repair. The stated primary endpoint concerned bony ingrowth at the anchor site, assessed by CT at 2 years. The brief summary describes additional MRI, CT and ultrasound imaging, along with questionnaires. The record states that MRI and radiographs were intended to assess bony ingrowth and ultrasound to assess repair success. It does not give a full schedule of visits or specify which assessments were completed for each participant.

Enrollment and an outcome analysis population are not interchangeable. The record does not report the number randomized to each arm, the number assessed at the primary endpoint, or reasons for missing assessments or exclusions. It also does not report protocol deviations, treatment adherence, crossover, or whether participants were analyzed according to their assigned group. These omissions limit what can be inferred about conduct and completeness from the registration alone.

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

Analysis population for the primary outcome, as defined in the registry: The Ossification Quality Score will be assessed for each anchor implanted into a study subjects' shoulder. Because many subjects have more than one rotator cuff suture anchor implanted, the overall number of units analyzed will be greater than the overall number of participants analyzed.

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 Ossification Quality Score (Bony Ingrowth Assessed Via CT), measured over 2 years.

The primary endpoint is the Ossification Quality Score, an ordinal assessment of bony ingrowth at each implanted suture anchor, assessed via CT at 2 years. The score has four progressive categories: score 1 indicates little or no bone ossification; score 2 indicates some ossification that is discontinuous or has a wide lucent rim; score 3 indicates ossification with a thin lucent rim; and score 4 indicates good ossification with a vague tract border. For the stated comparison, scores 1 and 2 are combined as low-quality ossification, while scores 3 and 4 are combined as high-quality ossification.

The endpoint is used to compare the proportions of anchors classified as high or low quality between the two groups. In general, reducing an ordinal scale to two categories can make a group comparison easier to express, but it discards distinctions among scores within each category. The registry record does not report whether the original four-category score was also analyzed or how the category boundaries were selected beyond the stated grouping.

The unit of measurement matters. The endpoint is assessed for each anchor, not simply once per participant. The record notes that participants could have more than one anchor implanted, so the number of analyzed units could exceed the number of participants analyzed. Multiple anchors from one participant may share characteristics; general statistical practice would consider this clustering when estimating uncertainty. The record does not report the analysis method used to account for it. Although the endpoint is described as a proportion comparison, no observed proportions or inferential results are reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Randomization is intended, in general, to make treatment assignment independent of participants' measured and unmeasured baseline characteristics. If implemented as planned and analyzed appropriately, it can support a fair comparison between groups. The registry records randomized allocation and a parallel model. It does not report the randomization sequence method, allocation concealment, or whether the final analysis followed assigned group. Those details are relevant to evaluating the protection randomization offers in practice.

What does the endpoint measure?

The primary outcome is an ordinal score: its categories have a meaningful order from little or no ossification through good ossification. The registry then combines the lower two categories into low-quality ossification and the upper two into high-quality ossification. A binary comparison of these grouped outcomes can be summarized using the proportion of anchors in the high-quality category in each arm. The record does not report the observed proportions or an estimated contrast, so no numerical comparison can be interpreted.

Collapsing categories can simplify communication, but it loses information about how observations are distributed across the original levels. For example, the grouped high-quality category cannot distinguish score 3 from score 4. General statistical interpretation should therefore keep the scale definition in view. The registry record does not state whether an analysis retaining all ordinal categories was planned or performed.

Why does the unit of analysis matter?

Randomization is assigned to participants, while the primary outcome is recorded for each anchor. The record notes that a participant may have more than one anchor. Measurements from the same participant may be more alike than measurements from different participants because they share clinical and biological characteristics. This is called clustering. In general, an analysis that ignores positive within-participant correlation can produce standard errors that are too small and confidence intervals that are too narrow. Methods such as clustered standard errors or models that represent the participant-level grouping can address this issue, depending on the design and analysis aims. The registry record does not identify the method used.

The distinction between a participant-level and anchor-level estimand is also important. An anchor-level proportion gives weight to anchors, whereas a participant-level summary would give weight to participants. These can answer different questions when people contribute different numbers of anchors. The registry describes the primary outcome as a proportion of suture anchors, but does not report further details about weighting or the estimand used in the analysis.

What would uncertainty measures tell readers?

In general, a point estimate summarizes the observed contrast, while a confidence interval conveys uncertainty around that estimate under the statistical model. A p-value, if reported, addresses how compatible the data are with a specified null hypothesis under the test assumptions; it does not measure the probability that the null hypothesis is true, and it does not communicate clinical importance by itself. Neither a primary-outcome estimate, its confidence interval nor a test result is reported in the registry record. Statistical significance and precision therefore cannot be assessed.

The registry lists a planning illustration based on a stated fraction of the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such planning calculations are hypothetical sample-size illustrations, not observed power and not evidence that the study was designed around the observed effect. Numerical illustration results are not reported in the registry record. The trial's own sample-size justification and design assumptions are not reported in the registry record. No claim about the adequacy of enrollment for detecting the endpoint can be made from the recorded enrollment alone.

How should multiple outcomes be considered?

The registry includes a primary endpoint and secondary outcomes covering re-tear, pain, function and quality of life. When several outcomes or comparisons are tested, the chance of at least one apparently positive finding can increase if all are treated as independent opportunities for significance. General approaches include prespecifying a primary comparison, adjusting inference for multiplicity, or treating secondary analyses as exploratory. The registry record does not report a multiplicity strategy, an analysis hierarchy, or results for the secondary outcomes. The description that the primary outcome was not reduced to one comparison also means a single primary statistical contrast cannot be reconstructed from the registry information.

What can be concluded from missing statistical details?

The registry record does not report its statistical analysis plan, handling of missing outcome data, analysis populations, or the number of participants and anchors included in the primary analysis. These absences prevent assessment of whether exclusions, incomplete imaging or deviations from assigned treatment could affect the comparison. They also prevent reproduction of an analysis from the registered information. They should be treated as reporting gaps, not as proof that the study did not use these methods or that its results are biased.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary endpoint and several secondary outcome areas, including re-tear, pain, shoulder function and quality of life. It does not report a statistical analysis plan specifying how multiple outcomes, scales, time points or comparisons were handled. In general, testing many outcomes without an adjustment or a prespecified hierarchy can increase the chance of a false-positive result. An adjustment is not the only possible strategy, but readers need to know whether secondary analyses were confirmatory or exploratory. That information is not reported in the registry record.

The primary endpoint itself is described through four ordinal categories that are grouped into high- and low-quality classifications for the stated comparison. The registry notes that this outcome has several categories or time points and was not reduced to one comparison. It does not report which specific comparison or comparisons were analyzed, or whether any additional time-point analyses were planned.

Missing-data handling is not reported in the registry record. The record does not state how absent CT assessments, incomplete questionnaires, withdrawals or other unavailable measurements were handled. It also does not report an analysis population, the number contributing to each outcome, or whether participants were analyzed according to randomized assignment. Enrollment is recorded as 64, but that figure alone does not establish the analyzed population for any endpoint.

These omissions do not show that data were missing or that an inappropriate method was used. They mean that completeness, assumptions about missingness and the robustness of any analysis cannot be evaluated from the registry record. The primary outcome's anchor-level unit further requires clarity about how multiple anchors per participant were handled; that method is 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 non-serious adverse event terms

The registry lists serious adverse events for the HEALICOIL Regenesorb group as 0 among 26 at risk, and for the Twinfix Ultra HA group as 0 among 26 at risk. Deaths are recorded as 0 in both groups. For other adverse events, the record lists 0 among 26 at risk in the HEALICOIL Regenesorb group and 1 among 26 at risk in the Twinfix Ultra HA group. No serious adverse-event terms are listed.

These are descriptive counts for the groups and at-risk populations recorded in the registry. They should not be treated as a complete safety comparison or as evidence that a device is safer than the other. The registry record does not report event definitions, event timing, severity details for the other event, exposure duration, or whether all randomized participants were included in these at-risk counts. With no serious events recorded in either group, a comparative estimate for serious-event risk cannot be inferred from these figures alone. The other-event count is also too limited, as reported, to support a broad conclusion about relative safety. Safety interpretation should remain restricted to the recorded counts and the information absent from the registry record.

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

The record establishes that a randomized parallel-group comparison was registered for two suture anchors used in rotator cuff repair, and that the primary endpoint was a CT-based assessment of anchor ossification quality at 2 years. It also defines how the ordinal quality scores were grouped for the planned high-versus-low comparison. These details make the intended research question understandable.

However, the registry record does not report an analyzed primary-outcome result. The stated expectation of 85% high-quality ossification for HEALICOIL REGENESORB and 49.9% for TWINFIX Ultra HA is a hypothesis, not an observed effect. Without reported outcome counts, estimates and uncertainty, the comparative result cannot be judged. No conclusion that the anchors differ, or that they are similar, follows from the absence of a reported analysis.

The record's enrollment figure is not a substitute for endpoint-specific data. It does not reveal the numbers assessed by CT, the number of anchors analyzed, or how many participants contributed multiple anchors. Those details matter both for completeness and for the precision of an anchor-level comparison. In general, multiple observations from one participant are not necessarily independent, and the analytic treatment of that clustering can influence uncertainty.

The listed adverse-event counts are descriptive and do not establish comparative safety. Likewise, the named secondary outcomes do not constitute results: no analyzed re-tear, pain, function or quality-of-life comparisons are reported in the registry record. The most defensible interpretation is therefore about what the study set out to assess, rather than what it found. The registered design and endpoint are informative, but the clinical and statistical outcome of the comparison remains unreported in this record.

13. Why This Trial Matters Statistically

This trial raises a useful design issue for clinical researchers: the unit measured may not be the unit randomized. Here, the primary outcome is measured for each suture anchor, while randomization is described at the participant level. When participants contribute multiple anchors, the analysis needs to account for the possibility that observations within a participant are correlated. Recognizing this distinction is essential for choosing an estimand and calculating uncertainty.

The endpoint also illustrates the consequences of simplifying an ordinal measure. Combining scores 1 and 2, and scores 3 and 4, creates a clear high-versus-low classification, but removes information about differences within each group. Readers need both the definition of the categories and the results from the planned comparison to understand what the endpoint can establish. The registry defines the categories but does not report the comparison's findings.

Finally, the record distinguishes a study hypothesis from an observed estimate, even though the two can be easy to conflate. The anticipated proportions are expectations stated in the study description, not findings. With no primary analysis reported, there is no basis for evaluating effect size, precision, statistical significance, or whether the data accorded with that expectation. This makes transparent reporting of outcome-specific denominators, analysis methods and uncertainty particularly important for a completed trial.

The case is statistically relevant not because the record establishes a comparative result, but because it shows what a design description can and cannot tell readers. Randomization and an explicit endpoint identify the intended comparison. They do not, on their own, reveal the observed effect, the handling of clustered measurements, or the completeness and precision of the analysis.

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 main limitation for interpretation is that the registry record does not report analyzed results for the primary endpoint. It also does not report the endpoint-specific counts, estimates, confidence intervals or statistical tests needed to assess the comparison. The registered hypothesis cannot stand in for those results.

The primary outcome is measured at the anchor level, and the record notes that participants may have more than one anchor. It does not report the number of anchors or participants in the analysis, or how dependence among anchors from the same participant was handled. This makes it difficult to assess the outcome unit, precision and relevance of any potential estimate.

The registry does not report the statistical analysis plan, sample-size justification, missing-data methods, analysis population, multiplicity strategy, or handling of protocol deviations. These omissions limit assessment of how the planned methods relate to the reported study conduct. The record also describes masking differently in its structured field and official title, without explaining the difference.

The brief summary describes several imaging and questionnaire assessments, but the registry does not report their analyzed findings. The adverse-event data are limited to the listed counts and at-risk groups, without further detail on event definitions, timing or exposure. These limitations concern what can be established from the registry record; they do not demonstrate that the study failed to collect data or that any particular analysis was inappropriate.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Suture Anchor Comparison in Rotator Cuff Repairs — NCT02350647.
• Registry record last updated 2021-01-13; status last verified 2021-01.
• Results first posted 2020-05-05.
• 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 describes a completed randomized, parallel-group study comparing HEALICOIL REGENESORB with TWINFIX Ultra HA for rotator cuff repair. Enrollment is recorded as 64, with the study start listed as 2014-05 and primary completion as 2019-03. The primary endpoint was anchor-level ossification quality assessed via CT at 2 years, with scores grouped into high- and low-quality categories.

The study description states hypotheses for the proportion of high-quality ossification at 24 months, but these are not observed results. The registry record does not report an analyzed primary-outcome comparison, its precision, or findings for the listed secondary outcomes. It records no serious adverse events in either listed group, and one other adverse event in the Twinfix group. Important details about outcome analysis, missing data, analysis populations and handling of multiple anchors are not reported in the registry record.