This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for PMCF Study on the Safety and Performance of the Alloclassic Variall Cup Ceramic Bearing System in Total Hip Arthroplasty (NCT03672370), a registered phase not stated study. The primary outcome is Clinical Success Will be Based on the Harris Hip Scoring System.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03672370 |
| Phase | Phase not stated |
| Condition | Avascular Necrosis, Osteoarthritis, Inflammatory Arthritis |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 100 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Zimmer Biomet |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people receiving total hip arthroplasty with the Alloclassic Variall Cup Ceramic Bearing System. The listed conditions are avascular necrosis, osteoarthritis, inflammatory arthritis, and posttraumatic arthritis. The primary outcome description says the Harris Hip Score was developed for assessment in an adult population, but the registry record does not report additional eligibility details or a fuller description of the study population.
Intervention
The intervention was the Alloclassic Variall Cup Ceramic Bearing System, described in the arm record as the system received by participants. The study was a post-market clinical follow-up study. The registry record describes it as prospective, multicenter, non-randomized, non-controlled, and based on a consecutive cohort.
Comparator
No comparator group is described. The study is explicitly non-controlled, so it does not provide a concurrent control arm for a like-for-like comparison. The record does not state an allocation method for a comparison, and no randomized comparison is reported.
Primary question
The primary outcome asks about the Harris Hip Score at 3 years. The score covers pain, function, absence of deformity, and range of motion, with scores from 0 to 100. The description also defines clinical success using a modified Harris Hip Score threshold and pain rating. However, the registry record does not report the observed mean, standard deviation, success count, or other primary outcome results, so the stated question cannot be answered from the posted results.
3. Trial Design
This was a multicenter, prospective, non-randomized, non-controlled, consecutive cohort post-market clinical follow-up study of the Alloclassic Variall Cup Ceramic Bearing System in total hip arthroplasty. Its registry title describes an assessment of safety and performance. Because there is no control group, the design is descriptive rather than a controlled comparison of the device with an alternative. The record does not describe random assignment or a comparator treatment.
The recorded enrollment is 100. That figure describes the enrollment entry in the registry; the record does not provide an analysis population count alongside primary outcome results. The listed conditions are avascular necrosis, osteoarthritis, inflammatory arthritis, and posttraumatic arthritis. The arm description identifies participants who received the cup system. Further eligibility criteria, recruitment details, or characteristics of participants at baseline are not reported in the registry record.
The primary outcome is the Harris Hip Score, specified as a mean with standard deviation and a timeframe of 3 years. The description discusses a modified Harris Hip Score definition for clinical success and failure, while the outcome title refers to the Harris Hip Scoring System. The registry record does not clarify this wording or report the score results. Oxford Hip Score and EQ-5D are listed as secondary outcomes, but their results are not reported in the registry record. Four outcome measures are recorded, while the additional measure details are not reported in the registry record.
The study began on 2015-03-24, and the primary completion date is 2019-05-14. Its status is terminated. The registry record does not report why the study was terminated, whether the planned follow-up was completed, or whether termination affected outcome collection. Those points should not be inferred from the status label 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
| Stage | Alloclassic Variall Cup |
|---|---|
| STARTED | 89 |
| COMPLETED | 42 |
| NOT COMPLETED | 47 |
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.
| Characteristic | Unit | Alloclassic Variall Cup |
|---|---|---|
| Participants analysed | 89 | |
| Age, Continuous | years | 63.9 (SD 9.0) |
| Sex: Female, Male: Female | Participants | 51 |
| Sex: Female, Male: Male | Participants | 38 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: Austria | participants | 89 |
| BMI | kg/m^2 | 29.0 (SD 1.2) |
6. Primary Endpoint
The registry lists the primary outcome as Clinical Success Will be Based on the Harris Hip Scoring System, measured over 3 years.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | score on a scale |
| Endpoint classification | Continuous Endpoint |
The primary outcome is the Harris Hip Score, a continuous measure of hip status. The registry describes its domains as pain, function, absence of deformity, and range of motion. The score ranges from 0 to 100, with the registry specifying a mean and standard deviation as the summary measures and 3 years as the timeframe. This makes the outcome a measure of participant status at a stated follow-up point rather than a direct comparison between treatment groups.
The registry description says the score was developed to assess results of hip surgery and evaluate hip disabilities and methods of treatment in an adult population. That explains its intended role as a structured clinical assessment. The description separately defines clinical success using a modified Harris Hip Score greater than 80 with a rating of mild or no pain, and failure using a modified score less than 80. The registry record does not say how a score of exactly 80 is classified, nor does it report how the modified score relates to the mean score named in the primary outcome title.
No observed mean, standard deviation, or clinical-success result is reported in the registry record. Consequently, the endpoint description establishes what was intended to be assessed, but not what the assessment found.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes the intended primary assessment and the study design, but does not report the primary outcome results. In particular, it gives no observed Harris Hip Score mean or standard deviation at 3 years, and no reported count or proportion meeting the clinical-success definition. The posted results therefore do not establish the observed score distribution or the degree of precision around an estimated score.
The absence of a control group is central to interpretation. A cohort followed after receiving the device can describe outcomes recorded among its participants, but without a concurrent comparator it cannot isolate the device’s contribution from other influences. Changes in health, surgical care, rehabilitation, participant characteristics, and the course of the underlying condition can all be relevant in general to outcomes after surgery. The registry does not report analyses that account for such influences. This is not evidence that any particular influence affected the results; it explains why a non-controlled design supports a different kind of inference from a controlled comparison.
The registry lists a planned enrollment of 100 and a primary completion date of 2019-05-14, but does not report the number with an outcome measurement at the primary time point, the amount of missing outcome information, or the analysis population. The enrollment figure should not be treated as the number contributing to an outcome analysis. The study status is terminated, but the reason and its implications for follow-up are not reported in the registry record.
The safety entries list 7 serious adverse events and 2 other adverse events in the Alloclassic Variall Cup group, with 89 at risk for each listed category and 1 death. These are counts as recorded, not evidence by themselves about causation or comparative risk. The record specifically labels the death as of unknown reason and not related to the device. The serious-event terms include infection and periprosthetic fractures requiring revision, each reported as 2.2%, and other listed terms. These entries describe what was recorded; they do not establish whether the device caused an event.
There are no listed analyses in the registry record. That does not establish that no analyses were conducted outside the record, but it means statistical estimates, uncertainty intervals, adjustment methods, and formal tests cannot be evaluated from the posted registry information. The resulting interpretation must remain limited to the stated design, outcome definitions, and safety counts.
9. Statistical Methods Explained
The registry identifies the primary outcome as a continuous measure summarized by a mean and standard deviation. In general, a mean describes the central level of measured scores, while a standard deviation describes how spread out individual scores are around that mean. These statistics answer different questions: the mean describes average score, whereas the standard deviation describes variation among measured participants. Neither is reported for the primary outcome in the registry record, so the observed score level and spread cannot be assessed.
What does a confidence interval add?
In general, a confidence interval expresses uncertainty around an estimate, such as a mean. A narrower interval indicates greater precision under the assumptions of the method; a wider interval indicates less precision. It does not describe the range containing most individual participant scores. No confidence interval for the primary outcome is reported in the registry record, and no method for calculating one is listed. Therefore, the precision of the estimated Harris Hip Score cannot be evaluated from the posted results.
How does the success definition relate to the score?
The primary outcome title names the Harris Hip Scoring System and describes a mean score. Its narrative definition additionally refers to a modified score greater than 80 with mild or no pain as clinical success, and less than 80 as failure. In general, turning a continuous score into categories can make a threshold-based clinical definition easier to communicate, but it discards some of the detail in the underlying score. The registry does not report success or failure counts, and the handling of a score of exactly 80 is not reported in the registry record. The description also does not clarify whether the continuous mean and the modified-score classification were both analyzed as primary outcomes.
What can a non-controlled cohort estimate?
In general, a prospective cohort follows participants forward and can document outcomes over the specified follow-up. Without a control group, it does not directly estimate how outcomes would differ under an alternative treatment or no treatment. Prospective follow-up can define when outcomes are collected, but it does not remove the possibility that observed outcomes reflect several factors together. The registry calls this study non-randomized and non-controlled; no comparative treatment effect is reported.
How should the analysis record be read?
The registry records 4 outcome measures and 0 analyses. This means that outcome measures are listed, but no analyses are listed in the registry record. It does not establish that study investigators performed no analyses elsewhere. No statistical test, model, covariate adjustment, missing-data procedure, or approach to repeated measurements is reported in the registry record. Without those details or numerical outcome results, readers cannot assess how the primary outcome was estimated or whether the posted analysis followed the stated outcome definition.
What do the planning assumptions mean?
The planning illustration assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with a target effect defined as a stated fraction of an observed effect. The description says that time-to-event illustrations use the total number of events, while other illustrations use participants per arm. These are planning assumptions, not observed study findings. This trial is described as non-controlled and has an arm description for the device cohort, so the two-arm equal-allocation setup does not describe its reported design. No observed effect estimate is reported in the registry record, and no illustration values are included in the registry information. Thus no numerical planning requirement or achieved power can be inferred from the registry record. In general, a planning calculation is conditional on its assumed effect and design; it is not a measure of the probability that the completed study detected an effect.
Over-dispersion is a general concern when observed variability exceeds what a statistical model assumes. If a model understates variability, its uncertainty estimates can be too small and inferential conclusions too confident. The registry record does not report a model or dispersion assessment for this continuous outcome, so there is no basis for saying that over-dispersion was assessed or present. For a continuous score, examining the distribution and variability can help evaluate modeling assumptions, but the necessary participant-level data and analysis details are not reported.
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.
| Arm | Participants | Mean | Standard deviation | 95% CI for the mean |
|---|---|---|---|---|
| Alloclassic Variall Cup | 42 | 92.600 | 8.900 | 89.827 to 95.373 |
R code and output
arm <- c("Alloclassic Variall Cup")
n <- c(42)
m <- c(92.6)
sp <- c(8.9)
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 Alloclassic Variall Cup 42 92.600 8.900 89.827 95.37311. Multiplicity, Missing Data and Analysis Populations
The registry lists Oxford Hip Score and EQ-5D as secondary outcomes, in addition to the primary Harris Hip Score. It records 4 outcome measures overall, but does not give all measure details or report results for the secondary outcomes. The registry record also lists 0 analyses. It therefore does not report a testing hierarchy, multiplicity adjustment, or a plan for interpreting several outcomes together. In general, when researchers make many statistical comparisons, the chance of at least one apparently notable finding can increase unless the analysis plan accounts for that multiplicity. This is a general consideration, not a statement that such a procedure was or was not applied outside the record.
Missing outcome data are also important for interpreting a follow-up measure. The registry does not report how many participants had a Harris Hip Score at 3 years, how many lacked the measure, or why any data were missing. It does not specify an imputation method, a complete-case analysis, or a sensitivity analysis. The recorded enrollment of 100 does not establish the number included in the primary outcome analysis. In general, missingness can affect both the representativeness of the analyzed group and the precision of an estimate; the direction and extent of any effect depend on circumstances not reported.
The analysis population is not reported in the registry record. There is no stated intention-to-treat, per-protocol, or safety analysis population description. Because this is a non-randomized, non-controlled cohort, an intention-to-treat comparison between assigned groups is not described. The registry also does not explain how participants with incomplete follow-up, protocol deviations, or score values outside the stated classification would be handled. These omissions prevent assessment of the relationship between enrollment, follow-up, and the population underlying any result.
12. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Alloclassic Variall Cup | 7 | 89 | 7.9% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Alloclassic Variall Cup | 1 of 89 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Alloclassic Variall Cup | 2 of 89 |
Most frequent serious adverse event terms
| Event term | Organ system | Alloclassic Variall Cup |
|---|---|---|
| Infection, revision required | Infections and infestations | 2 of 89 |
| Periprosthetic fractures, revision required | Musculoskeletal and connective tissue disorders | 2 of 89 |
| Lung cancer, unknown treatment | Respiratory, thoracic and mediastinal disorders | 1 of 89 |
| Traumatic event at outpatient rehab, surgical fragment fixation | Musculoskeletal and connective tissue disorders | 1 of 89 |
| Death, unknown reason, no relation to device | Vascular disorders | 1 of 89 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Alloclassic Variall Cup |
|---|---|---|
| femoral implant loosening | Musculoskeletal and connective tissue disorders | 1 of 89 |
| Pain in hip when sitting down, radiating to the knee | Musculoskeletal and connective tissue disorders | 1 of 89 |
Serious events with the highest arm-level rate: infection, revision required (2.2%), periprosthetic fractures, revision required (2.2%), lung cancer, unknown treatment (1.1%), traumatic event at outpatient rehab, surgical fragment fixation (1.1%), death, unknown reason, no relation to device (1.1%).
The safety record lists the Alloclassic Variall Cup group with 89 at risk for serious adverse events and 7 serious adverse events. It separately lists 89 at risk for other adverse events and 2 other adverse events, as well as 1 death. These entries are counts reported for the categories in the registry; they should not be read as a controlled comparison or as proof that the device caused an event. The registry does not report a comparator group.
The listed serious-event terms include infection requiring revision at 2.2% and periprosthetic fractures requiring revision at 2.2%. Other listed terms are lung cancer with unknown treatment at 1.1%, a traumatic event at outpatient rehabilitation with surgical fragment fixation at 1.1%, and death of unknown reason, listed as not related to the device, at 1.1%. These term-specific percentages are reported as stated in the registry. They do not supply a causal assessment for each event beyond the explicit note attached to the death.
In general, adverse-event counts describe recorded events, while a risk comparison requires an appropriate comparator and clear information about follow-up and event ascertainment. The registry record does not provide those comparative results or fuller details about how events were collected. The listed figures should therefore be understood as safety reporting for the cohort, not as a comparative estimate of device-related risk.
13. What the Result Does, and Does Not, Mean
The study record establishes that a prospective, multicenter, non-controlled post-market follow-up study was registered for the Alloclassic Variall Cup Ceramic Bearing System. It identifies a Harris Hip Score outcome at 3 years, describes the score’s domains and range, lists secondary outcomes, and includes adverse-event counts and terms. These details indicate what the study was intended to assess and what safety information was entered in the registry.
The record does not report the primary score results. There is no mean or standard deviation for the Harris Hip Score, and no reported result for the modified-score clinical-success definition. It also gives no results for Oxford Hip Score or EQ-5D. The registry therefore cannot establish what scores participants had at follow-up, how much scores varied, or how many met the stated success definition. The lack of reported outcome results is not evidence of a favorable or unfavorable outcome.
Even if outcome results were available, the non-controlled design would limit causal interpretation. Without a comparison group, the record cannot estimate how outcomes would differ under another treatment. Nor can the safety counts alone determine whether recorded events were caused by the device, except for the registry’s specific classification of the death as not related to the device.
The recorded enrollment, study dates, and terminated status provide context, but do not resolve missing outcome information. The reason for termination, follow-up completeness, and analysis population are not reported in the registry record. The statistical methods used to analyze the outcomes are also not listed. Accordingly, the posted results support a description of the study framework and selected safety entries, but do not support an estimate of performance or a comparative claim about safety.
14. Why This Trial Matters Statistically
This study matters statistically because it illustrates the distinction between a stated outcome and an available result. A registry can define a primary measure, its follow-up timeframe, and its intended summary statistics without reporting the measurements needed to estimate the outcome. Here, the Harris Hip Score is specified at 3 years, with a mean and standard deviation, yet those observed statistics are not reported in the registry record. Knowing the outcome definition is essential, but it is not a substitute for the outcome data.
The design also shapes the questions the study can address. A prospective cohort can record follow-up after device use, while a non-controlled design does not supply a concurrent comparison for estimating differences between treatment strategies. Keeping those distinctions clear prevents descriptive safety counts or an outcome definition from being mistaken for evidence of comparative performance.
The clinical-success wording highlights another important issue: a continuous score and a threshold-based classification are not interchangeable. The score retains gradations across its 0-to-100 range; a success or failure label applies a cutoff and pain criterion. The registry does not report results for either presentation, and it does not explain how a score exactly at 80 is classified. Clear reporting of definitions and results would be necessary to understand both the score distribution and any threshold-based conclusion.
Finally, the absence of listed analyses, analysis-population information, and missing-data methods limits reproducibility and appraisal. These are general features that help readers judge precision, bias, and the scope of inference. The registry record’s limitations are especially relevant for a terminated study, because the reason for termination and its relation to follow-up are not reported. The statistical importance is not that the design or record proves a particular result, but that conclusions should match the evidence actually documented.
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 most consequential trial-specific limitation in the registry record is that the primary outcome is described without numerical results. No mean or standard deviation for the Harris Hip Score at 3 years is reported, and no result is given for the modified-score definition of clinical success or failure. This prevents assessment of the observed outcome and its precision.
The study is explicitly non-controlled, so it does not provide a like-for-like comparator for interpreting outcomes or safety. It is also described as non-randomized. The record does not report an allocation approach, and it does not give sufficient information to evaluate how participants entered the cohort beyond calling it consecutive. Baseline characteristics and further eligibility details are not reported in the registry record.
The registry status is terminated, but the reason is not reported. The primary completion date is 2019-05-14, yet the record does not state whether follow-up was complete at that point or whether termination affected the planned assessments. It records enrollment of 100 but does not provide the number with primary outcome data. Missingness, analysis populations, and methods for incomplete data are not reported.
The outcome description refers to both a Harris Hip Score mean and a modified-score threshold, without reporting their results or clarifying their relationship. The treatment of a score exactly equal to 80 is not reported in the registry record. Although Oxford Hip Score and EQ-5D are listed, their results are absent. The registry lists 4 outcome measures but does not describe them all in detail, and it lists 0 analyses. Consequently, statistical models, adjustment, uncertainty estimates, and multiplicity procedures cannot be assessed.
Safety entries provide event counts and selected terms, but the record does not report a control group, comparative safety analyses, or fuller event-collection details. The listed events therefore do not support a causal estimate.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: PMCF Study on the Safety and Performance of the Alloclassic Variall Cup Ceramic Bearing System in Total Hip Arthroplasty — NCT03672370.
- Registry record last updated 2021-01-14; status last verified 2020-11.
- Results first posted 2021-01-14.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
The registry record describes a prospective, multicenter, non-randomized, non-controlled consecutive cohort post-market follow-up study of the Alloclassic Variall Cup Ceramic Bearing System in total hip arthroplasty. The recorded enrollment is 100, the study began on 2015-03-24, the primary completion date is 2019-05-14, and the status is terminated. The primary outcome is a mean Harris Hip Score with standard deviation at 3 years; Oxford Hip Score and EQ-5D are listed as secondary outcomes.
The record does not report primary or secondary outcome results, analysis populations, missing-data methods, or statistical analyses. Safety reporting includes 7 serious adverse events, 2 other adverse events, and 1 death in the device group, with the event terms and percentages stated in the registry. The non-controlled design and absence of outcome results limit interpretation to the study description and the reported safety entries.