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 28 mm Ceramic-on-Ceramic Acetabular Cup Total Hip Replacement Study (NCT00208507), a randomized na study. The primary outcome is Harris Hip Total Score.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00208507 |
| Phase | NA |
| Condition | Joint Diseases |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 264 |
| Arms in the primary outcome | n/a |
| Lead sponsor | DePuy Orthopaedics |
| Results posted | Yes |
2. Clinical Question
Population
People undergoing total hip replacement for joint diseases. The registry record does not report more specific eligibility criteria or a fuller description of the population evaluated for the primary outcome.
Intervention
Total hip replacement with a 28 mm ceramic head and ceramic acetabular liner, identified as the Delta Ceramax Ceramic-on-Ceramic Acetabular Cup System.
Comparator
Total hip replacement with a 28 mm ceramic head and polyethylene liner, identified as the Pinnacle Acetabular Cup with Marathon Polyethylene.
Primary question
How did Harris Hip Total Score outcomes compare between the ceramic-on-ceramic and ceramic-on-polyethylene systems at the recorded follow-up assessments?
The comparison holds the stated ceramic head size and material constant while distinguishing the systems by the liner material. The study summary says the purpose was to evaluate whether the ceramic-on-ceramic artificial hip performed as well as the ceramic-head, polyethylene-liner artificial hip. That is the stated research aim; it does not establish that a particular statistical test of equivalence or non-inferiority was planned or performed.
The primary outcome was assessed at 6 weeks, 6 months, 12 months, and a final evaluation at 24 months or greater, up to 96 months. The registry record does not report numerical Harris Hip Total Score results for these assessments. Consequently, the comparison’s direction, size, and precision cannot be described from the record. The specific patient eligibility criteria, the characteristics of participants at baseline, and the population included in each outcome analysis are not reported in the registry record.
3. Trial Design
The registry record describes a randomized, single-masked, parallel-group device study. Participants were assigned to one of two total hip replacement systems: a 28 mm ceramic head with a ceramic acetabular liner, or a 28 mm ceramic head with a polyethylene liner. The record lists enrollment of 264 and identifies DePuy Orthopaedics as the sponsor. The study status is completed.
The listed study start date is 2003-04-01, and the primary completion date is 2012-01-05. These dates identify the recorded study timeline; they do not establish how long any individual participant was followed. The Harris Hip Total Score assessment schedule included 6 weeks, 6 months, 12 months, and a final evaluation at 24 months or greater, up to 96 months. The registry record does not report how many participants contributed scores at each assessment or how follow-up varied among participants.
Single masking is recorded, but the masked party or parties and the procedures used to maintain masking are not reported in the registry record. The allocation sequence method, allocation concealment procedures, and details of how random assignment was implemented are also not reported. The record identifies a parallel design, meaning the two treatment groups are compared as separate groups rather than as a crossover sequence, but it does not provide further design or conduct details.
The study lists complication rates as a secondary outcome and reports adverse-event summaries. The registry record does not describe the planned analysis methods for the primary outcome, the basis for the enrollment target, or any interim analyses. The phase is listed as NA. The numerical primary-outcome results and the analysis populations used for the reported outcomes are not reported in the registry record, so the design description alone cannot establish how the study’s main comparison turned out.
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 | Delta Ceramax™ Ceramic-on-Ceramic Acetabular Cup System | Pinnacle™ Acetabular Cup With Marathon® Polyethylene |
|---|---|---|
| STARTED | 177 | 87 |
| COMPLETED | 163 | 79 |
| NOT COMPLETED | 14 | 8 |
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 | Delta Ceramax™ Ceramic-on-Ceramic Acetabular Cup System | Pinnacle™ Acetabular Cup With Marathon® Polyethylene | Total |
|---|---|---|---|---|
| Participants analysed | 177 | 87 | 264 | |
| Age, Continuous | years | 56.4 (SD 10.6) | 57.3 (SD 10.3) | 56.7 (SD 10.5) |
| Sex: Female, Male: Female | Participants | 87 | 40 | 127 |
| Sex: Female, Male: Male | Participants | 90 | 47 | 137 |
| Region of Enrollment: United States – United States | Participants | 177 | 87 | 264 |
6. Primary Endpoint
The registry lists the primary outcome as Harris Hip Total Score, measured over The Harris Hip Total Score evaluation took place at 6 weeks, 6 months, 12 months, and a final evaluation at 24 months or greater (up to 96 months).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Units on a scale |
| Endpoint classification | Continuous Endpoint |
Harris Hip Total Score is the primary endpoint named in the registry record. It is a continuous score in units on a scale. The record describes a scoring range from zero to 100, with higher score bands classified as excellent, good, fair, or poor. The score combines patient-reported information and surgeon assessments rather than measuring a single symptom or physical finding.
The listed score components include pain, need for assistance when walking, limp, walking distance, putting on shoes and socks, climbing stairs, use of public transportation, and the length of time a person can sit comfortably in a chair. Taken together, these items are intended to describe aspects of hip-related symptoms and function. A composite score can summarize several relevant domains in one measure, while also making clear that a single total may not show which particular component drove a change.
The registry record specifies assessments at 6 weeks, 6 months, 12 months, and a final evaluation at 24 months or greater, up to 96 months. Repeated assessments can describe scores at different follow-up stages, but interpretation depends on the number of participants assessed at each stage and the analysis used. Those details, along with the numerical score results, are not reported in the registry record. The reason this endpoint was selected over other possible outcomes is not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies Harris Hip Total Score as the primary outcome and describes its measurement schedule, but it does not report the numerical scores, group means, measures of variability, between-group comparisons, confidence intervals, or p-values. Thus, the record does not support a conclusion about the observed difference in scores between the two implant systems, or about how precisely such a difference was estimated. The study’s stated aim was to evaluate whether the ceramic-on-ceramic system performed as well as the ceramic-on-polyethylene system; an aim is not itself evidence that a particular performance relationship was demonstrated.
The outcome is continuous and the record specifies mean and standard deviation as its summary form. In general, a group mean describes the center of observed scores, while a standard deviation describes how spread out individual scores are around that mean. A mean difference between groups, if reported, would describe the contrast in average scores. A confidence interval would show a range of estimates compatible with the data under the analysis assumptions, and would help convey precision. No such primary-outcome estimates or intervals are reported in the registry record, so these concepts cannot be applied to a trial-specific numerical result.
The outcome was assessed at several follow-up stages, including a final evaluation whose timing could extend from 24 months or greater up to 96 months. A score comparison at one assessment would not necessarily answer the same question as a comparison across all assessments or a model of change over time. The registry record does not provide a single reduced comparison for this primary outcome, and the reported information does not establish whether any time-point-specific or longitudinal analysis was conducted. It also does not give the number of participants with observed scores at each assessment.
The adverse-event summaries describe events separately from the primary score outcome. They should not be treated as evidence of a difference in Harris Hip Total Score, and the primary score cannot be inferred from the adverse-event counts. Likewise, the enrollment total does not reveal how many participants were included in a particular outcome analysis or how much precision the score comparison achieved.
The statistical interpretation is therefore constrained: the trial’s design and intended score measure are described, but the primary numerical results needed to assess the comparison are absent from the registry record. The posted adverse-event counts can be read descriptively, with attention to their reported denominators, but they do not fill that gap. Neither the study aim nor the existence of a randomized design supplies the missing estimates. Any statement about the direction, magnitude, statistical uncertainty, or clinical importance of the primary outcome would require results that are not reported in the registry record.
9. Statistical Methods Explained
The registry record classifies the primary measure as continuous and identifies the mean and standard deviation as its summary statistics. These terms describe the kind of outcome and the way it is summarized; they do not by themselves specify a statistical test, a model, or an adjustment strategy. The analysis method for the primary outcome is not reported in the registry record.
What a mean and standard deviation describe
In general, the mean is an average that summarizes the location of observed values. The standard deviation describes how dispersed the values are around that average. Reporting both helps distinguish a group with a particular average score and a relatively tight spread from one with the same average but more varied participant scores. The record gives the intended summary form but does not include the numerical group summaries for Harris Hip Total Score.
What a between-group estimate would mean
In general, a comparison of group means estimates how far apart the average outcomes are between groups under a specified analysis. Its interpretation depends on which participants and assessments are included, how missing scores are handled, and whether the analysis adjusts for other variables. A confidence interval communicates uncertainty around an estimated contrast; it is not a guarantee that the true value lies in the interval. A p-value addresses compatibility of the data with a specified null hypothesis under the analysis assumptions, rather than measuring the size or importance of an effect. The registry record does not report a primary-outcome contrast, interval, p-value, or the assumptions used to calculate them.
Repeated assessments and follow-up
The score was scheduled at 6 weeks, 6 months, 12 months, and at a final evaluation at 24 months or greater, up to 96 months. In general, repeated scores from the same participant are related rather than independent observations. An analysis of change over time or of multiple assessments would need to account for that within-participant relationship. A separate comparison at each time point poses a different interpretation from an analysis that estimates an overall pattern across follow-up. The registry record does not say which approach was planned or used, nor does it report score availability at each assessment.
Longer follow-up can also mean that participants have different observation durations or that fewer participants contribute later measurements. These possibilities make the number assessed and the handling of missing observations important to interpretation. They are general considerations, not claims about what occurred in this study. The registry record does not report missing-data methods or the number of participants contributing primary-outcome data at the listed times.
Randomization and masking
Random assignment is intended, in general, to make the groups comparable with respect to factors that could influence outcomes, including factors that were not measured. It does not ensure that every feature is balanced in a particular trial, and it does not replace reporting the analysis population and outcome data. The record identifies the study as randomized, but the sequence-generation and allocation-concealment methods are not reported in the registry record. The record also identifies single masking without stating who was masked or how masking was maintained.
The listed parallel design means participants were assigned to one of the two systems rather than receiving both in sequence. This describes the structure of the comparison; it does not establish that the analysis followed the original assignment or identify whether participants were analyzed according to treatment received. Those analysis details are not reported in the registry record.
Planning and sample size
The record gives enrollment of 264, but the sample-size justification, target effect, assumed variability, and planned power are not reported in the registry record. A planning calculation based on an observed effect would be an illustration of the sample size that might be needed under stated assumptions. It would not be observed power and would not substitute for the actual trial’s design justification. No planning sample-size values are reported in the registry record.
The record does not provide the numerical primary results needed for a recalculated comparison from posted summary statistics. In general, such a recalculation would be a simple unadjusted estimate and could differ from a sponsor’s prespecified or adjusted analysis if one were reported. No sponsor primary-outcome analysis is reported in the registry record, so there is no trial-specific statistical estimate to compare or prioritize.
10. Multiplicity, Missing Data and Analysis Populations
The primary score has several planned assessment times: 6 weeks, 6 months, 12 months, and a final evaluation at 24 months or greater, up to 96 months. When a study assesses an outcome repeatedly or tests multiple outcomes, multiplicity can arise because several comparisons create more opportunities for a result to appear notable by chance. In general, statistical plans may address this by identifying one primary comparison, using a prespecified model, or adjusting for multiple tests. The registry record does not report a multiplicity strategy or identify a single time point as the primary comparison.
Complication rates are listed as a secondary outcome, and the registry record also includes adverse-event summaries. It does not report whether secondary outcomes were adjusted for multiple comparisons, whether they were considered confirmatory or exploratory, or how any hierarchy among outcomes was defined. The primary outcome’s numerical results are not reported, so its relationship to the secondary outcome findings cannot be assessed.
Missing data are especially relevant when an outcome is assessed repeatedly. In general, participants may have unavailable measurements for reasons that affect interpretation, and different statistical methods rely on different assumptions about those missing observations. The record does not state how missing scores were handled, how many participants contributed data at each assessment, or whether sensitivity analyses were conducted.
The registry record also does not report the primary outcome analysis population, such as whether participants were analyzed according to randomized assignment or another defined group. It does not describe exclusions, protocol deviations, or how participants who changed or did not receive their assigned system were treated in analysis. These omissions prevent a full assessment of which participants the reported primary comparison would represent, even if numerical results were available.
11. 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 |
|---|---|---|---|
| Delta Ceramax™ Ceramic-on-Ceramic Acetabular Cup System | 27 | 177 | 15.3% |
| Pinnacle™ Acetabular Cup With Marathon® Polyethylene | 14 | 87 | 16.1% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Delta Ceramax™ Ceramic-on-Ceramic Acetabular Cup System | 4 of 177 |
| Pinnacle™ Acetabular Cup With Marathon® Polyethylene | 3 of 87 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Delta Ceramax™ Ceramic-on-Ceramic Acetabular Cup System | 80 of 177 |
| Pinnacle™ Acetabular Cup With Marathon® Polyethylene | 44 of 87 |
Most frequent serious adverse event terms
| Event term | Organ system | Delta Ceramax™ Ceramic-on-Ceramic Acetabular Cup System | Pinnacle™ Acetabular Cup With Marathon® Polyethylene |
|---|---|---|---|
| Musculoskeletal | Musculoskeletal and connective tissue disorders | 16 of 177 | 8 of 87 |
| Cancer | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 3 of 177 | 2 of 87 |
| Gastrointestinal | Gastrointestinal disorders | 2 of 177 | 2 of 87 |
| Endocrine/Metabolic | Endocrine disorders | 1 of 177 | 2 of 87 |
| Cardiovascular | Cardiac disorders | 1 of 177 | 0 of 87 |
| Dislocation | Injury, poisoning and procedural complications | 0 of 177 | 1 of 87 |
| Neurological | Nervous system disorders | 1 of 177 | 0 of 87 |
| Genitourinary | Renal and urinary disorders | 1 of 177 | 0 of 87 |
| Respiratory | Respiratory, thoracic and mediastinal disorders | 1 of 177 | 0 of 87 |
| Acetabular liner failure | Surgical and medical procedures | 1 of 177 | 0 of 87 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Delta Ceramax™ Ceramic-on-Ceramic Acetabular Cup System | Pinnacle™ Acetabular Cup With Marathon® Polyethylene |
|---|---|---|---|
| Musculoskeletal | Musculoskeletal and connective tissue disorders | 68 of 177 | 36 of 87 |
| Cardiovascular | Cardiac disorders | 11 of 177 | 6 of 87 |
| Genitourinary | Renal and urinary disorders | 10 of 177 | 7 of 87 |
| Wound Problem | Injury, poisoning and procedural complications | 9 of 177 | 2 of 87 |
Serious events with the highest arm-level rate: musculoskeletal (9.2%), endocrine/metabolic (2.3%), gastrointestinal (2.3%), cancer (2.3%), dislocation (1.1%).
The registry record reports serious adverse events for the two groups. For the Delta Ceramax Ceramic-on-Ceramic Acetabular Cup System, 27 participants were affected among 177 at risk. For the Pinnacle Acetabular Cup with Marathon Polyethylene, 14 were affected among 87 at risk. The reported figures for other adverse events are 80 affected among 177 at risk in the ceramic-on-ceramic group and 44 among 87 at risk in the polyethylene-liner group. Deaths are listed as 4 and 3, respectively. These are descriptive counts with the at-risk totals stated in the record; they are not adjusted comparisons.
The registry record lists serious-event terms and percentages including Musculoskeletal, 9.2%; Endocrine/Metabolic, 2.3%; Gastrointestinal, 2.3%; Cancer, 2.3%; Dislocation, 1.1%; and Cardiovascular, 0.6%. The record does not specify the denominator or detailed coding rules for these percentages in the information presented, so they should be read as registry-listed summaries rather than converted into participant counts or interpreted as comparative risks.
Event counts alone do not establish whether the groups differed statistically or whether an event was caused by a study device. The registry record does not report adjusted safety comparisons, confidence intervals, or a fuller account of event timing and severity. These safety summaries also do not provide the missing numerical results for the primary hip score.
12. What the Result Does, and Does Not, Mean
This registry record describes a randomized comparison of two total hip replacement systems with the same stated ceramic head size but different acetabular liner materials. It identifies Harris Hip Total Score as the primary outcome and gives the planned assessment schedule. It also reports adverse-event counts and selected serious-event categories. These registry entries establish what was compared and what kinds of outcome information the record contains.
The record does not report the primary score results. It therefore cannot show whether average scores were higher in one group, how large any difference was, or how uncertain that difference might be. The study’s stated goal of evaluating whether one system performed as well as the other is not a reported finding. Without numerical estimates and their uncertainty, the record cannot establish equivalence, non-inferiority, superiority, or absence of a difference.
The adverse-event figures offer descriptive information about events reported for participants in each group. They do not, by themselves, establish a causal relationship with a device, a statistically supported difference between groups, or the overall balance of benefits and harms. The listed categories also do not identify the details needed to interpret when events occurred or how they were adjudicated.
More generally, a result’s statistical significance and its practical importance are distinct questions. Statistical evidence concerns how compatible observed data are with a specified model or hypothesis, while practical importance concerns whether the magnitude of an outcome difference matters in context. Neither can be judged for the primary comparison from the information reported in the registry record. The score’s descriptive categories do not replace group estimates or a prespecified interpretation of between-group differences.
The appropriate reading is limited to the study’s design, named outcome, assessment schedule, and posted safety summaries. The record does not provide enough primary-outcome information to determine how the systems compared on Harris Hip Total Score. That limitation should not be turned into a claim that the systems were the same or different; the numerical comparison is simply not reported in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically notable for the structure of its question: it compares two device systems that share a stated 28 mm ceramic head but use different liner materials. Randomized assignment is intended to support a fair comparison by reducing systematic differences between groups, while the parallel design keeps the groups separate. The registry record also identifies single masking, though it does not explain who was masked or how.
The primary outcome is a composite continuous score assessed repeatedly, rather than a single event count at one time. That creates important interpretive questions about which follow-up assessment drives the comparison, how correlated scores from the same participant are handled, and how incomplete follow-up is addressed. The registry record states the assessment schedule but does not report an analysis method or numerical score results, leaving those questions unresolved.
The record illustrates why a study’s aim and design are not substitutes for outcome estimates. It states a goal of evaluating whether one system performed as well as the other, but the primary results needed to assess that aim are not reported. Without group summaries and a between-group estimate with uncertainty, neither the direction nor precision of the primary comparison can be described.
The posted safety counts are informative as descriptive summaries, but they also demonstrate the need to distinguish counts from comparative inference. Counts and at-risk totals do not themselves provide adjusted estimates, uncertainty intervals, or causal attribution. The missing analysis details limit how far the safety summaries can be interpreted statistically.
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 numerical Harris Hip Total Score results are not reported in the registry record. The record names the outcome, identifies mean and standard deviation as the summary form, and gives its assessment schedule, but does not give group scores or a comparative estimate. That prevents an assessment of the primary result’s magnitude, direction, or precision.
Several details needed to evaluate the design and analysis are also not reported in the registry record. These include eligibility criteria, baseline participant characteristics, random-sequence generation, allocation concealment, the identity of the masked party, primary-outcome analysis methods, and the population included in each analysis. The record does not explain how missing scores or deviations from assigned treatment were handled.
The follow-up schedule includes multiple assessments, with the final evaluation occurring at 24 months or greater and extending up to 96 months. The number of participants assessed at each time and the methods used to account for repeated observations are not reported. Without those details, the completeness and comparability of follow-up cannot be evaluated from the record.
The safety summaries include counts and selected serious-event categories, but do not report adjusted comparisons, confidence intervals, or detailed event definitions and timing. The registry record also does not report the sample-size justification, planned power, interim analyses, or a multiplicity strategy. These omissions do not establish that such procedures were absent; they mean that they are not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: 28 mm Ceramic-on-Ceramic Acetabular Cup Total Hip Replacement Study — NCT00208507.
- Registry record last updated 2023-11-07; status last verified 2023-10.
- Results first posted 2011-02-16.
- 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.
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18. Record Summary
The completed study is a randomized, single-masked, parallel-group comparison of two total hip replacement systems. Both use a 28 mm ceramic head; one uses a ceramic acetabular liner and the other a polyethylene liner. The record lists enrollment of 264 and identifies DePuy Orthopaedics as the sponsor.
Harris Hip Total Score is the primary outcome, assessed at 6 weeks, 6 months, 12 months, and a final evaluation at 24 months or greater, up to 96 months. The record does not report numerical results for this outcome or the methods used to analyze it. Complication rates are listed as a secondary outcome, and adverse-event counts and selected serious-event categories are reported.
The posted information describes the trial question, design, outcome measure, and safety summaries. It does not provide the primary estimates needed to determine the observed score comparison or its precision.