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 SCP® Observational Study of the Knee (NCT03110224), a registered phase not stated study. The primary outcome is Change From Baseline Visual Analog Scale (VAS) Pain Scale at 12 Months.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03110224 |
| Phase | Phase not stated |
| Condition | Bone Marrow Edema |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 516 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Zimmer Biomet |
| Results posted | Yes |
2. Clinical Question
Population
The registry lists Bone Marrow Edema as the condition. The study concerns subjects undergoing or who had undergone the Subchondroplasty Procedure in the knee. Enrollment is 516; the number contributing data to each outcome is not reported in the registry record.
Intervention
The intervention is the Subchondroplasty Procedure with AccuFill, recorded as a device intervention. The stated purpose is to collect clinical outcomes in a standard clinical setting.
Comparator
A comparator is not reported in the registry record. Allocation is not stated, and the record does not describe a randomized comparison. The study should therefore not be read as a like-for-like comparison between treatment arms.
Primary question
The primary outcome is change from baseline in Visual Analog Scale pain score at 12 months. The registry record names the outcome but does not report its observed mean change or 95% confidence interval.
The clinical question is descriptive: what short- and long-term outcomes are observed among subjects undergoing or having undergone the procedure in routine clinical settings? The registry summary says outcomes of interest include pain medication usage, pain, function, activity levels, and patient satisfaction. The listed primary outcome narrows one part of that broader question to pain intensity measured with a Visual Analog Scale at baseline and 12 months.
Because the record does not state allocation or identify a comparator, the primary question is not whether the procedure performs better than another intervention. Instead, the registered outcome concerns change over time in the cohort. Even a complete estimate of within-cohort change would describe the recorded participants and would not, by itself, isolate the effect of the procedure from other influences on pain over time.
The registry lists a secondary outcome concerning occurrence and severity of device- and/or procedure-related adverse events and revisions or re-operations. The available record includes adverse-event counts and selected serious-event terms, but it does not provide a 12-month pain result or a detailed account of who contributed data to that outcome.
3. Trial Design
This is a post-market observational cohort follow-up study, not a randomized trial. Its official title identifies it as a Zimmer Knee Creations SCP® Observational Cohort Follow-Up Study, and the sponsor is Zimmer Biomet. The intervention is the Subchondroplasty Procedure with AccuFill. The registry describes the intended setting as standard clinical practice and says the study was intended to collect short- and long-term outcomes among subjects undergoing or previously having undergone the procedure.
The registry reports enrollment of 516. That figure is the recorded enrollment, not necessarily the number with complete data for every outcome or the number included in an analysis. The analysis population and outcome-specific participant counts are not reported in the registry record. The record lists a start date of 2012-09-18, a primary completion date of 2020-09-16, and a status of TERMINATED. The reason for termination is not reported in the registry record.
The primary outcome is change from baseline in mean Visual Analog Scale pain score at 12 months, with a 95% confidence interval specified as the dispersion measure. A secondary outcome concerns occurrence and severity of device- and/or procedure-related adverse events and revisions or re-operations. The registry metadata lists two outcome measures and zero analyses. No detailed statistical analysis plan, follow-up schedule beyond the stated endpoint timeframe, or account of outcome-specific analysis populations is reported in the registry record.
Allocation is not stated, and the registry does not describe a randomized comparison. No comparator group is identified in the record. This design can describe the course and outcomes recorded in the cohort, but without a suitable comparison it cannot separate changes observed over time from other factors that may also influence those outcomes.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: Of 516 patients enrolled, 508 had data entered that could be used for analysis.
Overall Study
| Stage | Subchondroplasty |
|---|---|
| STARTED | 516 |
| COMPLETED | 133 |
| NOT COMPLETED | 383 |
Reasons for not completing this period:
| Reason | Subchondroplasty |
|---|---|
| Death | 3 |
| Lost to Follow-up | 132 |
| Physician Decision | 2 |
| Site Closed by Physician | 35 |
| Site Closed by Sponsor | 202 |
| Withdrawal by Subject | 9 |
Analysis population for the primary outcome, as defined in the registry: Visual Analog Scale was analyzed at baseline to 12 months.
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 | Baseline |
|---|---|---|
| Participants analysed | 516 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 299 |
| Age, Categorical: >=65 years | Participants | 215 |
| Age, Continuous: Age | years | 56.77 (SD 12.63) |
| Sex: Female, Male: Female | Participants | 272 |
| Sex: Female, Male: Male | Participants | 236 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | Participants | 516 |
| BMI | kg/m2 | 31.53 (SD 6.71) |
6. Primary Endpoint
The registry lists the primary outcome as Change From Baseline Visual Analog Scale (VAS) Pain Scale at 12 Months, measured over 12 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | score on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change from baseline in Visual Analog Scale (VAS) pain score at 12 months. The scale is a 10 cm horizontal line, with 0 cm indicating “no pain” and 10 cm indicating “worst possible pain.” A patient marks the line, and an administrator measures the distance from its left end to the mark in centimeters. Lower scores represent lower pain levels.
The endpoint uses a continuous measure: its planned summary is a mean, with a 95% confidence interval. In general, a continuous outcome preserves the measured score rather than reducing it to categories. Measuring at baseline and again at 12 months allows the registered outcome to describe change over time in pain scores for the analyzed participants. The registry says the VAS was analyzed from baseline to 12 months.
Pain is included among the outcomes because the registry’s stated study purpose includes collecting information on pain, alongside medication usage, function, activity levels, and satisfaction. The 12-month measure provides a defined follow-up point for one of those outcomes. However, the registry record does not report the mean change, confidence interval, number analyzed, or the method used to handle incomplete paired measurements. The endpoint definition therefore describes what was intended to be measured, not the magnitude or precision of an observed result.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clinically interpretable primary outcome and a defined follow-up timeframe, but it does not report the outcome estimate. In particular, it provides no mean change from baseline in VAS pain score at 12 months and no 95% confidence interval. The direction and size of any observed cohort change, and the precision with which it was estimated, are therefore not reported in the registry record. The status of TERMINATED does not fill that gap or establish what results were obtained.
Enrollment is listed as 516, but this does not establish that 516 participants had baseline and 12-month VAS measurements or entered an analysis. The number included in the primary-outcome analysis is not reported in the registry record. Without that information, the extent of missing follow-up data and the relationship between enrollment and the analyzed group cannot be assessed.
The observational design is central to interpretation. Allocation is not stated, and there is no identified randomized comparator. A change in the cohort’s mean score, if reported, would describe change among those measured; it would not alone show that the procedure caused the change. General influences on pain over time, differences among participants, additional care, and selective availability of follow-up measurements could matter, but their role cannot be evaluated from the registry entries.
The safety record lists 83 serious adverse events among 516 at risk, 17 other adverse events among 516 at risk, and 3 deaths. These are recorded counts, not an estimate of comparative safety. The record does not provide a comparator, event timing, participant-level overlap, or enough detail to establish the relation of each event to the device or procedure. Listed serious-event terms include Osteoarthritis at 9.1% and Increased Knee Pain at 2.1%; other terms are listed at 0.2%. Those terms are descriptive entries and do not, on their own, establish causality.
Registry metadata lists zero analyses. This means the record does not include analysis entries, not that every possible analysis was necessarily absent outside the record. The key statistical conclusion is consequently about reporting: the endpoint is defined, but its numerical result and precision are not reported in the registry record. No claim about benefit, lack of benefit, or comparative effect follows from the available outcome information.
9. Statistical Methods Explained
The primary endpoint is continuous and is specified as a mean change in VAS score from baseline to 12 months. In general, a mean describes the central level of measured values by averaging them. A change score compares measurements at two timepoints for participants with the required data. The registry names this outcome and its timeframe, but it does not report the observed mean change or the number of participants whose measurements contributed to it.
What does a 95% confidence interval describe?
In general, a confidence interval expresses the uncertainty around an estimate under the assumptions of the statistical method used. For a mean change, a narrower interval indicates greater precision than a wider interval, while the interval’s position gives information about the range of values compatible with the data and method. It is not a guarantee that an individual participant’s change lies within that interval. Here, the registry specifies a 95% confidence interval as the dispersion measure but does not report its endpoints. The precision of the primary result therefore cannot be assessed.
Why does the observational design matter?
In general, measuring outcomes before and after an intervention can describe temporal change, but it does not automatically identify what caused that change. A randomized comparison can help distinguish an intervention’s effect from other influences by assigning participants to comparison groups under a defined process. This study is described as observational; allocation is not stated, and no comparator is identified. Any reported within-cohort change would therefore need to be interpreted as an association over time rather than as a controlled estimate of the procedure’s effect.
What does the planning illustration mean?
The registry’s stated planning assumptions describe an illustration based on an observed effect, not the trial’s own design justification. The assumptions include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. In general, such illustrations show how a hypothetical design might be sized to detect a specified effect under stated assumptions. They are not observed results, do not establish that the trial had those arms or allocation, and are not observed power. The numerical planning results, the effect used, and the fractions considered are not reported in the registry record.
Why can over-dispersion matter?
In general, over-dispersion means that observed variability is greater than a statistical model assumes. When a model understates variability, standard errors may be too small and confidence intervals may be too narrow, making estimates appear more precise than the data warrant. The appropriate model depends on the outcome and data structure. The registry identifies a continuous mean outcome and a confidence interval, but it does not report a model, a variance assessment, or any adjustment for over-dispersion. It would therefore be inappropriate to claim that a particular model was used or that over-dispersion was present.
What can the adverse-event counts show?
In general, safety counts describe events recorded within a defined group and timeframe; they do not establish causation or comparative risk on their own. Interpretation depends on definitions, duration of observation, whether a person can contribute multiple events, and how relatedness is assessed. The record lists 516 at risk for both serious and other adverse events and gives counts of 83 and 17, respectively. It also lists 3 deaths. Event timing, person-level overlap, complete follow-up, and the methods for determining relatedness are not reported in the registry record. No comparative estimate can be derived from these counts because a comparator is not reported.
The registry metadata lists two outcome measures and zero analyses. The record does not specify how the mean and confidence interval were estimated, whether covariates were used, how missing measurements were treated, or which participants formed each analysis population. These gaps are important because statistical methods describe not only the summary statistic but also the data included and the assumptions supporting the estimate. Without an estimate and its analysis details, precision and robustness cannot be evaluated.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary pain outcome and a secondary outcome concerning device- and/or procedure-related adverse events and revisions or re-operations. Its metadata lists two outcome measures and zero analyses. The record does not report how many statistical tests were planned, whether any outcomes were designated as key secondary endpoints, or whether an adjustment for multiple testing was planned. A multiplicity strategy is therefore not reported in the registry record.
In general, testing several outcomes or timepoints can increase the chance of finding an apparently unusual result by chance if each is treated as a separate confirmatory test. A prespecified approach can clarify which comparisons are confirmatory and how uncertainty is managed across them. No such approach is described in the registry record, and there are no posted analysis entries from which to assess how multiplicity was handled.
The primary endpoint is defined as a baseline-to-12-month change, but the number of participants with measurements at both timepoints is not reported in the registry record. The record also does not describe imputation, complete-case analysis, or another method for handling missing measurements. Consequently, the extent of missing outcome data and the potential for differences between participants with and without follow-up cannot be assessed.
The analysis population is not described. Enrollment of 516 should not be assumed to equal the population analyzed for the primary endpoint or safety outcomes. The record does not state whether all enrolled participants were eligible for each analysis, how withdrawals were handled, or whether any exclusions occurred. These are not minor reporting details: they determine which participants the estimates would describe and how well they represent the enrolled cohort.
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 |
|---|---|---|---|
| Adverse Events | 83 | 516 | 16.1% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Adverse Events | 3 of 516 |
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 |
|---|---|
| Adverse Events | 17 of 516 |
Most frequent serious adverse event terms
| Event term | Organ system | Adverse Events |
|---|---|---|
| Osteoarthritis | Musculoskeletal and connective tissue disorders | 47 of 516 |
| Increased Knee Pain | Musculoskeletal and connective tissue disorders | 11 of 516 |
| Chondrosis: Patella and Medial Femoral Condyle | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Complex tear of medial meniscus of right knee | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Extensive chondrosis medial femoral condyle and medial tibial plateau | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Fall | General disorders | 1 of 516 |
| Increased grinding and retropatellar pain | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Infected right knee | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Known patellar chondrosis with recurrent effusions and pain | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Osteoarthritis with fracture | Musculoskeletal and connective tissue disorders | 1 of 516 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Adverse Events |
|---|---|---|
| Acute Cholecystitis | Gastrointestinal disorders | 1 of 516 |
| Arthroscopic Surgery | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Difficulty with dorsiflexion of left foot. | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Increased Knee Pain | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Left elbow pain | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Left knee draining sinus | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Left knee stress fracture lateral femoral condyle and impending OCD lesion | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Medial femoral condyle insufficiency fracture | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Osteoarthritis | Musculoskeletal and connective tissue disorders | 1 of 516 |
| Patient had signs of delirium postoperatively | General disorders | 1 of 516 |
Serious events with the highest arm-level rate: osteoarthritis (9.1%), increased knee pain (2.1%), chondrosis: patella and medial femoral condyle (0.2%), complex tear of medial meniscus of right knee (0.2%), extensive chondrosis medial femoral condyle and medial tibial plateau (0.2%).
The registry’s adverse-event group lists 516 participants at risk for serious adverse events and 516 at risk for other adverse events. It records 83 serious adverse events, 17 other adverse events, and 3 deaths. These are counts as listed in the record. They should not be converted into comparative claims, because no comparator is reported and the event definitions, timing, and participant-level overlap are not described in the available information.
The serious-event terms listed include Osteoarthritis at 9.1%, Increased Knee Pain at 2.1%, and Chondrosis: Patella and Medial Femoral Condyle, Complex tear of medial meniscus of right knee, Extensive chondrosis medial femoral condyle and medial tibial plateau, and Fall, each at 0.2%. The registry does not provide enough information to determine from these entries whether a term was judged related to the device or procedure, how long participants were followed for safety, or whether a person could contribute more than one event.
The listed secondary outcome concerns occurrence and severity of device- and/or procedure-related adverse events and revisions or re-operations. The counts alone do not establish that every listed event was caused by the procedure, nor do they establish a comparative safety profile. The registry record does not report further analysis details or an explanation of the 3 deaths.
12. What the Result Does, and Does Not, Mean
The record establishes that a post-market observational cohort study was registered to follow subjects undergoing or previously having undergone the Subchondroplasty Procedure in the knee. It identifies a primary outcome—mean change from baseline in VAS pain score at 12 months—and describes how that score is measured. It also lists a safety-related secondary outcome. Those details define the questions the study intended to address, but they are not themselves outcome findings.
The central limitation for interpreting the primary endpoint is that no observed mean change or 95% confidence interval is reported in the registry record. Without those values, it is not possible to describe the direction, magnitude, or precision of the measured change. Enrollment of 516 does not reveal how many participants posted both baseline and 12-month measurements. The registry also lists zero analyses, so no statistical estimate or analysis population is available in the record.
Even if a within-cohort change were available, the observational design and absence of a stated comparator would limit causal interpretation. In general, a before-and-after difference can reflect multiple influences over time, not only the intervention. The registry does not describe allocation, a control group, or an adjustment strategy that would support a comparative causal estimate. No conclusion about whether the procedure works or does not work should be drawn from the record’s endpoint definition or event counts.
The adverse-event entries give descriptive information: 83 serious events, 17 other events, and 3 deaths are listed for the group, along with selected serious-event terms. They do not provide a comparison or establish that an event was caused by the device or procedure. The details required to assess follow-up completeness, timing, and relatedness are not reported in the registry record.
Thus, the registry record supports a description of the study’s purpose, design category, registered outcomes, enrollment, and selected safety entries. It does not support a numerical conclusion about the primary pain outcome, its precision, or a comparative treatment effect. These are limits of what the record reports, rather than evidence about unreported results.
13. Why This Trial Matters Statistically
This study illustrates an important distinction in clinical statistics: a clearly named endpoint is not the same as a reported result. The registry specifies a continuous pain score, the baseline-to-12-month comparison, a mean summary, and a 95% confidence interval. Those choices indicate what the primary outcome was intended to capture. However, without the estimate, its interval, and the number analyzed, readers cannot evaluate either the observed change or its precision.
It also shows why study design must shape the language used to describe findings. This is an observational follow-up study, with allocation not stated and no comparator identified. In general, within-cohort changes can be useful for describing outcomes in routine settings, but they do not by themselves distinguish the intervention’s contribution from other changes over time. That distinction remains essential even when enrollment is substantial.
The record’s safety entries offer another statistical lesson: counts require context. The group lists 83 serious adverse events and 17 other adverse events among 516 at risk for each category, as well as 3 deaths. These entries can describe what was recorded, but the absence of a comparator, event timing, and details about relatedness limits what can be inferred. Counts should not be presented as proof of cause or comparative risk.
Finally, the registry lists zero analyses and does not report missing-data procedures, analysis populations, or multiplicity handling. These details affect the interpretation of estimates, not merely their presentation. A study’s registered aims can be informative, while an incomplete results record leaves key statistical questions unanswered. Recognizing that boundary is part of responsible interpretation.
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 primary limitation is that the registry record does not report the primary endpoint result. No mean change from baseline in VAS score at 12 months, 95% confidence interval, or analysis-specific participant count is available. The outcome definition is detailed, but the observed size and precision of any change cannot be assessed.
The study is observational, allocation is not stated, and no comparator is identified. This limits any causal or comparative interpretation of a change over time. The registry does not describe adjustment for other factors or any method intended to address confounding. It also does not state why the study was terminated.
Although enrollment is 516, the number contributing to the primary outcome or safety summaries is not separately reported. Follow-up completion, missing-data handling, withdrawal procedures, and analysis populations are not reported in the registry record. It is therefore not possible to determine whether the outcomes describe all enrolled participants or a subset with available measurements.
The record lists zero analyses and does not describe a detailed statistical analysis plan, model, multiplicity approach, or outcome-specific analysis methods. The safety entries do not provide event timing, participant-level overlap, or a detailed account of relatedness. The registry’s planning assumptions are illustrative and are not a substitute for a trial design justification or an observed analysis. Together, these omissions constrain assessment of precision, robustness, and generalizability.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: SCP® Observational Study of the Knee — NCT03110224.
- Registry record last updated 2025-10-28; status last verified 2024-12.
- Results first posted 2025-08-27.
- 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 record describes NCT03110224, the Zimmer Knee Creations SCP® Observational Cohort Follow-Up Study, sponsored by Zimmer Biomet. It is a post-market observational study of the Subchondroplasty Procedure with AccuFill in the knee. The registry lists Bone Marrow Edema as a condition and enrollment of 516. The study status is TERMINATED; the start date is 2012-09-18 and the primary completion date is 2020-09-16.
The primary outcome is mean change from baseline in VAS pain score at 12 months, with a 95% confidence interval specified. A secondary outcome concerns device- and/or procedure-related adverse events and revisions or re-operations. The record lists 83 serious adverse events, 17 other adverse events, and 3 deaths among the stated risk groups. It lists two outcome measures and zero analyses. The primary estimate, its confidence interval, analysis population, missing-data approach, and reason for termination are not reported in the registry record.