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 PEAK PlasmaBlade 4.0 Versus Traditional Electrosurgery in Total Knee Replacement. (NCT01081886), a randomized na study. The primary outcome is Post-operative Pain.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01081886 |
| Phase | NA |
| Condition | Degenerative Joint Disease, Osteoarthritis |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 24 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Medtronic Surgical Technologies |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people undergoing total knee replacement for degenerative joint disease or osteoarthritis. The registry record reports enrollment of 24 participants. Eligibility criteria and further details about the enrolled population are not reported in the registry record.
Intervention
The PEAK PlasmaBlade 4.0 was used for the entirety of total knee replacement, including the skin incision. The study objective included assessing operative performance and monitoring postoperative pain, activity, narcotic consumption, adverse events, and skin scarring.
Comparator
The comparison was traditional electrosurgery with a scalpel for the skin incision and traditional electrosurgery for subcutaneous dissection. This was described as the standard of care. The trial used a randomized, parallel-group design.
Primary question
The primary endpoint was postoperative pain during the period from 0 to 10 days after surgery, measured with the Wong-Baker FACES scale. The registry describes the endpoint as the mean of each participant’s mean pain scores over 10 days. An integrity audit found the data could not be analyzed because source documentation could not be verified, so the registry record does not report a usable comparison of pain between groups.
3. Trial Design
This was a prospective, randomized, controlled superiority study comparing the PEAK PlasmaBlade 4.0 with traditional electrosurgery in total knee replacement. It used a parallel-group design and was recorded as single masked. The identity of the people who were masked, the masking procedures, and whether masking was maintained are not reported in the registry record.
The registry record lists enrollment of 24 participants. The study start is recorded as 2010-06, and primary completion as 2011-09. Its status is terminated. The record names Medtronic Surgical Technologies as the sponsor. The study phase is listed as not applicable.
The intervention arm used the PlasmaBlade for the whole procedure, including the skin incision. In the standard-of-care arm, a scalpel was used for the skin incision and traditional electrosurgery for subcutaneous dissection. The registry does not report the method used to generate or conceal the random sequence, the intended allocation ratio, or the detailed recruitment and follow-up procedures.
The stated objective covered operative performance and postoperative outcomes, including pain, activity level, narcotic consumption, adverse events, and skin scarring. Operative time, estimated blood loss, skin scarring, and Knee Society Score are named as secondary outcomes. The integrity audit states that the study data could not be analyzed because source documentation was unverifiable. Consequently, the registry record does not provide a reliable estimate of the primary treatment contrast or a reported analysis of secondary 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.
Overall Study
| Stage | PlasmaBlade | Standard of Care (SOC) |
|---|---|---|
| STARTED | 11 | 13 |
| COMPLETED | 0 | 0 |
| NOT COMPLETED | 11 | 13 |
Reasons for not completing this period:
| Reason | PlasmaBlade | Standard of Care (SOC) |
|---|---|---|
| Study termination | 11 | 13 |
Analysis population for the primary outcome, as defined in the registry: An integrity audit found that the data for this study could not be analyzed owing to unverifiable source documentation.
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 | PlasmaBlade | Standard of Care (SOC) | Total |
|---|---|---|---|---|
| Participants analysed | 11 | 13 | 24 | |
| Age, Customized: 21 to 80 years | participants | 11 | 13 | 24 |
| Gender: Female | participants | NA | NA | 0 |
| Gender: Male | participants | NA | NA | 0 |
| Region of Enrollment: United States | participants | 11 | 13 | 24 |
6. Primary Endpoint
The registry lists the primary outcome as Post-operative Pain, measured over Postoperative (0 to 10 days).
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was postoperative pain from 0 to 10 days after surgery. It was measured using the Wong-Baker FACES Visual Analog Scale, described as ranging from 0 (no hurt) to 10 (hurts worst). The registry defines the endpoint as the mean of each participant’s mean pain scores over 10 days. It does not report a group-level pain value or a treatment-group comparison.
Pain is a patient-reported outcome: it captures the participant’s experience rather than an observation made only by the surgical team. As a general statistical point, repeated measurements over a period can describe the overall symptom burden across that period, while a prespecified summary can reduce many observations to a single participant-level outcome. The registry’s stated averaging approach is such a summary, but further details about when scores were collected and how incomplete daily records would be handled are not reported in the registry record.
The integrity audit found that the data could not be analyzed because source documentation was unverifiable. Therefore, the endpoint’s definition is available, but its observed values, between-group estimate, uncertainty, and statistical test are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a randomized comparison of two surgical approaches and identifies postoperative pain as the primary endpoint. It does not, however, report an analyzable primary outcome. The integrity audit specifically states that the data for the study could not be analyzed owing to unverifiable source documentation. Thus there is no reported pain estimate for either group and no reported estimate of the difference between groups.
Without an analyzable comparison, the posted information cannot establish whether the groups had similar or different postoperative pain scores. It also cannot establish superiority of either approach, despite the study’s superiority design. A superiority question depends on an interpretable estimate of the contrast and its uncertainty; the registry record gives neither for the primary endpoint. A direction of effect, confidence interval, or p-value for pain is not reported in the registry record.
The registry lists enrollment of 24 participants, and the adverse-event record gives at-risk counts of 11 for the PlasmaBlade group and 13 for the standard-of-care group. Those safety counts do not supply a primary-outcome analysis. They also do not establish that every enrolled participant contributed complete pain data or that the groups were analyzed according to their randomized assignments. The analysis population and handling of missing measurements are not reported in the registry record.
Secondary outcomes include operative time, estimated blood loss, skin scarring, and Knee Society Score. Although the study objective also refers to activity level and narcotic consumption, numerical outcome results and analyses for these measures are not reported in the registry record. The registry records no analyses. Consequently, neither the primary pain question nor the secondary outcome questions can be answered from the posted results.
In general, an estimate is more informative when its uncertainty is reported along with its direction and magnitude. Here, the absence of a usable estimate means precision cannot be assessed. This is not evidence that the groups had no difference; it is a limitation on what can be concluded from the registry record.
9. Statistical Methods Explained
What does randomization contribute?
Randomization assigns participants to study groups by chance. As a general statistical principle, it is intended to make the groups comparable, on average, with respect to both measured and unmeasured characteristics at the start of a trial. It does not guarantee that groups will be identical, particularly in a small study. This record identifies the study as randomized, but the sequence-generation method, allocation concealment, and intended allocation ratio are not reported in the registry record. The adverse-event counts describe 11 participants at risk in the PlasmaBlade group and 13 in the standard-of-care group; those counts alone do not explain how randomization was carried out.
What would a superiority comparison assess?
A superiority study asks whether the outcome differs between the intervention and comparator groups in a direction consistent with an advantage for the intervention. In general, the analysis requires a defined contrast, such as a difference in group means, and an assessment of uncertainty around that contrast. A confidence interval describes a range of values compatible with the data and analysis assumptions; a p-value assesses how unusual the observed data would be under a specified null hypothesis. Neither is a measure of clinical importance by itself. The registry record reports no primary endpoint estimate, confidence interval, or p-value, so these interpretations cannot be made for this trial.
How is the pain endpoint constructed?
The registry describes a 0 to 10 Wong-Baker FACES scale and defines the primary outcome as the mean of each participant’s mean pain scores over 10 days. In general, reducing repeated measurements to a participant-level summary can make the endpoint more manageable for a group comparison and can represent average pain over the stated period. This summary does not show the pattern of pain over time. The record does not report the timing and frequency of individual assessments beyond its description of the 10-day summary, the handling of incomplete records, or the statistical model that would have been applied.
For a continuous outcome such as a mean pain score, a general analysis might compare group averages or use a model that adjusts for prespecified covariates. Those are examples of possible approaches, not descriptions of analyses conducted in this study. The statistical analysis plan, covariate adjustments, distributional assumptions, and method for estimating uncertainty are not reported in the registry record. The integrity audit says the study data could not be analyzed because source documentation was unverifiable.
Why do assumptions matter?
Statistical methods rely on assumptions about the outcome and the data collection process. For example, the normal approximation used in some mean-based analyses may be less suitable when the outcome distribution is strongly skewed or when observations are highly influential. General methods can sometimes address such features, but choosing a method requires access to the underlying data and a prespecified analysis plan. Neither the data nor the plan needed to evaluate those choices is reported in the registry record.
Over-dispersion is a general concern when observed variability exceeds what a statistical model assumes. In that situation, standard errors may be too small if the model does not account for the extra variability, making uncertainty appear narrower than it is. This concept is relevant to some kinds of outcomes and models, but the registry record does not report a fitted model or data that would permit an assessment of over-dispersion. It would be inappropriate to claim that it occurred in this trial.
What do planning assumptions mean?
The record describes a planning illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect, and that non-time-to-event calculations are expressed as participants per arm. These are assumptions for a planning illustration, not evidence of the trial’s original design or its actual power. The trial’s own sample-size justification, target effect, and planning assumptions are not reported in the registry record. No analyzable primary effect is available to interpret as the basis for a clinically meaningful planning target.
Sample-size calculations are conditional on assumptions about the outcome, variability, target effect, allocation, and analysis. In general, they describe what a future study might require under those assumptions; they do not measure the probability that a completed study has found a real effect. The registry record does not support an observed-power claim. Since the primary data could not be analyzed, the planning illustration cannot repair the missing treatment estimate or its uncertainty.
What can be concluded about the analysis?
The registry lists no analyses, and no statistical analysis plan is reported in the registry record. The record does not state whether interim analyses were planned or performed, how multiplicity was handled, which participants were included in each outcome analysis, or how missing data were treated. These omissions matter because analysis choices can affect the interpretation of estimates and their uncertainty. With no verified source documentation and no analyzable primary outcome, statistical methods cannot produce a reliable treatment comparison from the information recorded.
10. Multiplicity, Missing Data and Analysis Populations
Multiplicity arises when several outcomes, time points, or statistical comparisons are assessed. As a general statistical principle, the more questions tested, the more important it is to define which comparison is primary and how any additional tests will be interpreted. The registry identifies postoperative pain as the primary outcome and names operative time, estimated blood loss, skin scarring, and Knee Society Score as secondary outcomes. The study objective also mentions activity level and narcotic consumption. A multiplicity strategy, hierarchy among secondary outcomes, or adjustment procedure is not reported in the registry record.
The record lists no analyses. It does not state which participants were included in the primary or secondary analyses, whether the analysis followed randomized assignment, or whether any outcomes were analyzed among participants with complete records only. The integrity audit reports that the data could not be analyzed because source documentation could not be verified. This is distinct from a report that a particular missing-data method was used: no such method is reported in the registry record.
The primary outcome description specifies a mean of each participant’s mean pain scores over 10 days, but the rules for incomplete pain records are not reported. The record also does not describe missingness for secondary outcomes, withdrawals, or outcome-specific denominators. Without those details, the completeness and representativeness of the outcome data cannot be assessed. The stated audit finding is the key limitation: no reliable outcome analysis is available for interpretation.
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 |
|---|---|---|---|
| PlasmaBlade | 3 | 11 | 27.3% |
| Standard of Care (SOC) | 1 | 13 | 7.7% |
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 |
|---|---|
| PlasmaBlade | 10 of 11 |
| Standard of Care (SOC) | 9 of 13 |
Most frequent serious adverse event terms
| Event term | Organ system | PlasmaBlade | Standard of Care (SOC) |
|---|---|---|---|
| Spider bite | Skin and subcutaneous tissue disorders | 1 of 11 | 0 of 13 |
| Pneumonia | Infections and infestations | 1 of 11 | 0 of 13 |
| Colitis | Gastrointestinal disorders | 1 of 11 | 0 of 13 |
| Bowel obstruction | Gastrointestinal disorders | 0 of 11 | 1 of 13 |
Most frequent non-serious adverse event terms
| Event term | Organ system | PlasmaBlade | Standard of Care (SOC) |
|---|---|---|---|
| Pain/swelling | Surgical and medical procedures | 6 of 11 | 4 of 13 |
| Effusion | Surgical and medical procedures | 2 of 11 | 2 of 13 |
| Vomiting | Gastrointestinal disorders | 1 of 11 | 1 of 13 |
| Insomnia | General disorders | 0 of 11 | 1 of 13 |
| Constipation | Gastrointestinal disorders | 0 of 11 | 1 of 13 |
| Diarrhea | Gastrointestinal disorders | 1 of 11 | 0 of 13 |
Serious events with the highest arm-level rate: spider bite (9.1%), pneumonia (9.1%), colitis (9.1%), bowel obstruction (7.7%).
The adverse-event record lists 11 participants at risk in the PlasmaBlade group, with 3 recorded as affected by serious adverse events and 10 affected by other adverse events. In the standard-of-care group, it lists 13 at risk, with 1 affected by serious adverse events and 9 affected by other adverse events. These are the registry’s participant counts; the record does not provide enough detail to determine event timing, severity beyond the serious classification, relationship to the procedure, or whether a participant experienced multiple events.
The registry also lists Spider bite, Pneumonia, and Colitis at 9.1% each, and Bowel obstruction at 7.7%, among the top serious-event terms. The group attribution and denominators for these term percentages are not reported in the registry record, so they should not be assigned to a study arm or interpreted as comparative rates. Death counts are not reported in the registry record.
As a general principle, adverse-event counts describe events recorded during a study; by themselves, they do not show that a device or procedure caused an event. The counts also do not support a reliable comparative safety conclusion without context about event definitions, follow-up, and analysis.
12. What the Result Does, and Does Not, Mean
The registry record identifies the clinical comparison and the intended primary question: postoperative pain after total knee replacement with the PEAK PlasmaBlade 4.0 versus traditional electrosurgery. It also describes how the pain endpoint was to be summarized. These details clarify what the investigators intended to evaluate, but they are not outcome findings.
The central limitation is that an integrity audit found the data could not be analyzed because source documentation was unverifiable. As a result, the posted results do not provide a pain score for either group, a between-group estimate, or a measure of precision. They do not show whether pain differed, whether one approach was superior, or whether the approaches were similar. An unavailable result should not be read as evidence of no effect.
The registry’s adverse-event counts are descriptive, and the record does not report a statistical safety comparison or causal assessment. Secondary outcomes are named, but their results are not reported in the registry record. The listed enrollment and safety counts cannot stand in for the missing primary endpoint analysis.
In general, a clinical trial result is most informative when it pairs an interpretable treatment estimate with uncertainty and sufficient information about the analysis population and data quality. This record documents a study design and an audit finding, but does not provide those outcome-analysis elements. Its contribution is therefore primarily to show what was intended to be studied and why the posted data do not support a treatment-effect conclusion.
13. Why This Trial Matters Statistically
This trial is statistically notable because it illustrates the difference between a well-defined research question and an interpretable result. The record specifies a randomized comparison, a primary pain endpoint, and a period over which pain was to be summarized. Yet the integrity audit reports that unverifiable source documentation prevented analysis. Without usable outcome data, the planned comparison cannot be translated into an estimate or an assessment of uncertainty.
Randomization can support a fair comparison when allocation and follow-up are adequately implemented and the data are reliable. It cannot compensate for an inability to verify the source records. This distinction matters when interpreting registry entries: the presence of a trial design and outcome definition does not mean that a treatment effect was successfully estimated.
The record also makes clear why transparent reporting of analysis populations, missing-data handling, outcome definitions, and statistical methods is important. Such details help readers understand what data entered an analysis and how conclusions depend on method choices. Here, the record lists no analyses, and important details of the statistical plan are not reported in the registry record.
Finally, the safety counts illustrate the limits of descriptive adverse-event information. Counts and listed terms can document what was recorded, but without fuller context and an interpretable comparative analysis they do not establish causation or a difference in safety. The trial’s statistical importance lies in the boundary between its intended questions and the conclusions supported by its posted results.
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 most direct limitation is the integrity audit finding that data could not be analyzed because source documentation was unverifiable. This prevents interpretation of the primary pain endpoint and leaves no reported effect estimate or uncertainty measure. The record does not describe what source documents were unavailable, the scope of the audit, or whether any subset of records could be verified.
Enrollment is listed as 24, but the registry does not report the numbers contributing data to the primary endpoint or the secondary outcomes. The adverse-event groups list 11 and 13 participants at risk, but these counts do not establish outcome completeness or analysis populations. Eligibility criteria, participant characteristics, withdrawals, and follow-up completeness are not reported in the registry record.
Although the trial is recorded as randomized and single masked, the randomization method, allocation concealment, and identity of the masked parties are not reported. The statistical analysis plan, model, handling of missing data, multiplicity approach, and interim-analysis arrangements are also not reported in the registry record. The record’s planning assumptions are described as an illustration rather than the original trial design, and no analyzable observed effect is available to evaluate that illustration.
The adverse-event information gives participant counts and selected serious-event terms, but the record does not provide event narratives, causal assessments, or the denominators and group attribution for the listed term percentages. Death counts are not reported in the registry record. These limitations restrict interpretation of both efficacy and safety; they do not resolve whether either approach differed on the intended outcomes.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: PEAK PlasmaBlade 4.0 Versus Traditional Electrosurgery in Total Knee Replacement. — NCT01081886.
- Registry record last updated 2013-01-08; status last verified 2013-01.
- Results first posted 2013-01-03.
- 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
NCT01081886 is a randomized, parallel-group, single-masked superiority study of PEAK PlasmaBlade 4.0 versus traditional electrosurgery in total knee replacement. The record lists enrollment of 24 participants, a study start of 2010-06, primary completion of 2011-09, and terminated status. Medtronic Surgical Technologies is named as sponsor.
The primary endpoint was postoperative pain from 0 to 10 days, measured with the Wong-Baker FACES scale and summarized as the mean of each participant’s mean pain scores over 10 days. An integrity audit found the data could not be analyzed because source documentation was unverifiable. No analyses are listed, and no primary treatment comparison or secondary outcome results are reported in the registry record.
The adverse-event record lists serious and other adverse-event counts by group, along with selected serious-event terms. Those descriptive figures do not provide a causal or comparative safety conclusion. The registry record documents the study’s intended questions, but the posted results do not support an estimate of the treatment effect.