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 Dynamic Locking Screws 5.0 vs. Standard Locking Screws in Fracture of Distal Femur Treated With Locked Plate Fixation (NCT01693367), a randomized phase 4 study. The primary outcome is Western Ontario and McMaster Universities Index (WOMAC).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01693367 |
| Phase | Phase 4 |
| Condition | Distal Femur Fractures |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 5 |
| Arms in the primary outcome | n/a |
| Lead sponsor | AO Innovation Translation Center |
| Results posted | Yes |
2. Clinical Question
Population
People with distal femur fractures treated with locked plate fixation were the intended population. Five patients signed informed consent and enrolled before the study was terminated. The registry does not provide further eligibility details or a more specific description of the enrolled participants.
Intervention
The intervention was ORIF with DLS 5.0, or Dynamic Locking Screws. The study purpose was to evaluate their performance when used to stabilize the shaft component of distal femur fractures.
Comparator
The comparator was ORIF with SLS, or a Standard Locking Screw. The registry describes the study as a randomized comparison of the two screw approaches, but does not report how randomization was generated or concealed.
Primary question
The primary endpoint was the Western Ontario and McMaster Universities Index (WOMAC), assessed 12 months after surgery to assess pain, stiffness, and physical function. The study hypothesis was that DLS would lead to better functional outcomes, with increased and more symmetrical callus formation and fewer non-unions. The registry does not report a WOMAC analysis or a result addressing that hypothesis.
3. Trial Design
The registry describes this as a multicenter randomized controlled pilot study with a parallel-group model and single masking. It lists the study as Phase 4. The interventions were devices: DLS 5.0 and SLS. Participants assigned to DLS received ORIF with Dynamic Locking Screws; those assigned to SLS received ORIF with a Standard Locking Screw. The registry record does not identify who was masked, describe the randomization method, or report allocation concealment.
The study concerned distal femur fractures treated with locked plate fixation. Its stated purpose was to evaluate the performance of dynamic screws compared with standard locking screws when stabilizing the shaft component of these fractures. It was intended as a pilot, but the registry record does not report a protocol, a sample-size justification, or other details about the pilot design.
Five patients signed the informed consent form and enrolled before the study was terminated. Three were post-enrollment drop-outs, and two completed all study follow-up visits. The registry lists a start date of 2012-09 and a primary completion date of 2014-12. It identifies the study status as terminated; the reason for termination is not separately reported in the registry record. The primary outcome description says that no analysis was done because of the low number of patients.
WOMAC at 12 months after surgery was the primary outcome. Listed secondary outcomes were the Timed Up-and-go Test, Quality of Life measured with EuroQol-5D, range of motion, full weight-bearing status, and WOMAC. The registry also lists six outcome measures overall. It does not provide results for these outcomes or a description of the timing and analysis of each secondary measure.
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: Five patients signed the informed consent form and were enrolled in the study before it was terminated. Three of the five patients were post-enrollment drop-outs and only two patients completed all study follow-up visits.
Overall Study
| Stage | DLS 5.0 (Dynamic Locking Screws) | SLS (Standard Locking Screw) |
|---|---|---|
| STARTED | 2 | 3 |
| COMPLETED | 1 | 1 |
| NOT COMPLETED | 1 | 2 |
Reasons for not completing this period:
| Reason | DLS 5.0 (Dynamic Locking Screws) | SLS (Standard Locking Screw) |
|---|---|---|
| Withdrawal by Subject | 1 | 1 |
| Physician Decision | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: Five patients signed the informed consent form and were enrolled in the study before it was terminated. Three of the five patients were post-enrollment drop-outs and only two patients completed all study follow-up visits. No analysis was done. Due to the low number of patients an analysis was not indicated, therefore no results are available.
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.
Population: Study was stopped
| Characteristic | Unit | DLS 5.0 (Dynamic Locking Screws) | SLS (Standard Locking Screw) | Total |
|---|---|---|---|---|
| Participants analysed | 2 | 3 | 5 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 | 2 | 3 |
| Age, Categorical: >=65 years | Participants | 1 | 1 | 2 |
| Age, Continuous | years | 68.5 (52 to 85) | 55 (23 to 71) | 60.4 (23 to 85) |
| Sex: Female, Male: Female | Participants | 1 | 2 | 3 |
| Sex: Female, Male: Male | Participants | 1 | 1 | 2 |
| Region of Enrollment: Switzerland | participants | 0 | 1 | 1 |
| Region of Enrollment: Germany | participants | 2 | 2 | 4 |
6. Primary Endpoint
The registry lists the primary outcome as Western Ontario and McMaster Universities Index (WOMAC), measured over 12 months after surgery.
| 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 the Western Ontario and McMaster Universities Index, or WOMAC, at 12 months after surgery. The registry says it was used to assess pain, stiffness, and physical function. In general, a patient-reported index such as WOMAC can describe how a person experiences symptoms and functional limitations, complementing measures based on clinical assessments or observed performance. Its relevance to this study follows from the stated interest in functional outcomes after fracture fixation.
The registry does not report a WOMAC score, its unit, a summary measure, a measure of dispersion, or an analysis. It therefore does not establish how scores were handled, what direction represented a better outcome, or whether any observed difference between the screw groups was estimated. The stated assessment time was 12 months after surgery, but the registry does not say whether endpoint data were available for either participant who completed all follow-up visits.
The study hypothesis connected functional outcomes with callus formation and non-union. Those are part of the rationale described in the registry, not reported findings. No endpoint result is available to evaluate the proposed relationship or to compare the groups on WOMAC.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The main statistical fact is that the registry reports no primary-outcome analysis. Five patients enrolled, three were post-enrollment drop-outs, and two completed all study follow-up visits. The registry explicitly says that no analysis was done because of the low number of patients. There is consequently no reported WOMAC group estimate, no estimated contrast between DLS and SLS, and no inferential result for the primary question.
This means the record cannot quantify the direction or size of a difference in pain, stiffness, or physical function. It also cannot show how precisely such a difference was estimated: there is no confidence interval or other uncertainty estimate reported for WOMAC. In general, a confidence interval describes a range of values compatible with the observed data under the analysis assumptions. It does not guarantee that the true effect lies within that range, and its width conveys information about precision. There is no such interval to interpret for this primary endpoint.
The registry's hypothesis is not a result. It describes the expected functional benefit of DLS in terms of increased and more symmetrical callus formation and fewer non-unions. The record does not provide an analysis of WOMAC, callus formation, or non-union that could support or refute that expectation. The absence of an analysis should not be interpreted as evidence that the devices have identical outcomes, or as evidence that one approach is better.
Safety counts are also limited. In the registry's adverse-event entries, zero participants are listed as affected by serious events among two at risk in the DLS group, and zero among three at risk in the SLS group. The corresponding counts for other adverse events are also zero. These are counts in a very small enrolled sample, not precise estimates of event frequency. Death counts are not reported. Event definitions, collection details, and further safety analyses are not reported in the registry record.
Because there is no outcome analysis, the posted results do not support a treatment-effect estimate or a formal comparison. They describe a terminated pilot with limited follow-up completion and no analysis of the primary endpoint. The registry record does not report whether any analyses were planned for the secondary outcomes, or whether a statistical analysis plan specified other methods.
9. Statistical Methods Explained
The registry labels the study randomized, single masked, and parallel. These terms describe design features, but do not supply the operational details needed to assess the methods fully. Random allocation is intended, in general, to reduce systematic differences between groups at assignment. The registry does not report the sequence-generation procedure, allocation concealment, or whether randomization was stratified. Single masking indicates that masking was used, but the masked party is not identified. It is not possible to determine from the record how these design features were implemented.
What does the absence of an analysis mean?
The primary outcome description states that no analysis was done because of the low number of patients. Accordingly, the registry does not report a comparison of WOMAC scores, a treatment-effect estimate, a standard error, a confidence interval, or a p-value. A p-value, in general, measures how incompatible the observed data are with a specified statistical model or null hypothesis, assuming that model and hypothesis. It does not measure the probability that a treatment works, and it cannot be interpreted when no such result is reported.
There are no reported outcome summaries from which to assess the observed variability or the extent to which the groups differed. There is also no reported adjusted analysis. The registry record does not report a statistical analysis plan, the model that would have been used for WOMAC, or whether the planned analysis would have adjusted for baseline characteristics. Those details should not be inferred from the randomized design alone.
How should precision be understood?
Precision concerns how much uncertainty surrounds an estimate. In general, estimates based on limited information tend to be less precise than estimates based on more information, but precision must be evaluated from the actual analysis and its uncertainty measures. Here, no primary-outcome estimate or uncertainty measure is reported, so there is no precision interval to interpret. The small enrollment and incomplete follow-up describe important constraints on the available study information; they do not permit calculation of an effect or uncertainty from the registry record.
The sample-size assumptions in the record describe a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The record does not provide a primary-outcome analysis or an observed effect estimate. Therefore, the reported trial information does not establish a usable observed WOMAC effect for interpreting such planning. Planning calculations are not observed power, and a sample-size illustration cannot substitute for an outcome analysis. The registry does not report the study's original sample-size justification.
Why can over-dispersion matter?
In general, over-dispersion occurs when observed variability is greater than a statistical model assumes. If it is ignored, uncertainty estimates can be too small and statistical conclusions can be misleading. Whether over-dispersion is relevant depends on the outcome and the model. The registry does not report a fitted model, WOMAC distribution, or variance estimate, so there is no basis for assessing over-dispersion in this study's primary endpoint.
What can be said about the endpoint structure?
WOMAC was named as the primary endpoint at 12 months after surgery, with pain, stiffness, and physical function as its assessment domains. The record does not specify a WOMAC scale, scoring approach, summary statistic, or handling of repeated measurements. It also does not describe whether baseline WOMAC was collected or incorporated in an analysis. No result is reported for the primary time point.
The record lists additional outcomes, including TUG, EuroQol-5D, range of motion, full weight-bearing status, and WOMAC. It does not report statistical methods for those measures or results by outcome. A single listed outcome can involve multiple measures, time points, or analytic choices; without an analysis plan and results, the exact scope of testing cannot be established. No multiplicity adjustment is reported, but the record also does not show that such an adjustment was or was not needed under a specified analysis.
What is not available for independent assessment?
The record does not describe the analysis population, missing-data method, imputation, handling of drop-outs, protocol deviations, or sensitivity analyses. Nor does it report whether outcomes were analyzed according to assigned group. These are distinct methodological decisions; their absence from the registry record means they cannot be assumed. In general, transparent reporting of these decisions helps readers understand how incomplete observations and analysis choices may affect conclusions.
Overall, the statistical methods that can be identified are limited to the registry's design labels and the statement that no analysis was done. There is no reported inferential procedure or primary-outcome estimate to interpret. Any explanation of concepts such as confidence intervals, p-values, or over-dispersion is general statistical context, not a description of an analysis performed in this trial.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists WOMAC as the primary outcome and names the Timed Up-and-go Test, EuroQol-5D, range of motion, full weight-bearing status, and WOMAC among the secondary outcomes. The record also lists six outcome measures overall. Since no analysis was done, it reports no outcome-specific tests or estimates and no approach to controlling multiplicity. Multiplicity concerns arise in general when multiple outcomes, time points, or comparisons are examined; the registry does not report enough about planned analyses to establish how they would have been handled.
Three of the five enrolled patients were post-enrollment drop-outs, while two completed all follow-up visits. Reasons for drop-out, timing of withdrawal, and availability of individual outcome measurements are not reported. The record does not describe a missing-data method, imputation, sensitivity analysis, or rules for excluding observations. It is therefore not possible to assess how missing information might have affected an endpoint analysis.
The analysis population is not reported. The registry does not say whether an intended analysis would have included all randomized patients, participants with available outcome data, or another group. It also does not report whether patients were analyzed according to assigned intervention. These analysis-population choices matter because they determine which observations contribute to an estimate, but no choice can be attributed to this study from the registry record.
The two participants who completed all study follow-up visits should not be treated as proof that complete primary-outcome data were available. The registry does not report their WOMAC measurements or any analysis of them.
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 |
|---|---|---|---|
| DLS 5.0 (Dynamic Locking Screws) | 0 | 2 | 0.0% |
| SLS (Standard Locking Screw) | 0 | 3 | 0.0% |
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 |
|---|---|
| DLS 5.0 (Dynamic Locking Screws) | 0 of 2 |
| SLS (Standard Locking Screw) | 0 of 3 |
The registry's adverse-event entries list zero participants affected by serious adverse events among two at risk in the DLS 5.0 group, and zero among three at risk in the SLS group. For other adverse events, the entries likewise list zero affected among two at risk for DLS 5.0 and zero among three at risk for SLS. These are the recorded counts; they should not be read as precise estimates of safety in a broader population.
The number of participants at risk is small, and the registry does not report additional event details, definitions, collection methods, or a safety analysis. A count of zero affected in this record does not establish that an event is impossible or that the groups have equivalent safety. It describes only what the posted results record for the enrolled participants and the specified categories.
Death counts are not reported in the registry record. They should not be interpreted as zero. The record also does not provide event terms in its list of top serious-event terms. No conclusion about relative safety can be drawn from these counts alone.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized pilot comparison of DLS 5.0 and SLS was conducted in people with distal femur fractures treated with locked plate fixation, and that five patients enrolled before termination. Three were post-enrollment drop-outs and two completed all follow-up visits. The registry says no analysis was done because of the low number of patients.
For the primary question, that leaves no reported WOMAC result at 12 months after surgery. There is no group comparison, effect estimate, confidence interval, or p-value to describe. The registry therefore does not show whether the groups differed in pain, stiffness, or physical function, nor how precisely a difference could be estimated. The stated study hypothesis is not evidence of an outcome.
The record also does not provide results for its listed secondary outcomes, or analyses of callus formation and non-union. It does not report an analysis population, missing-data procedure, or statistical plan. The serious and other adverse-event counts are descriptive entries from a very small sample, and death counts are not reported. They do not establish that the approaches have equivalent risks.
These limitations do not demonstrate that the devices are equivalent or different. They mean that the posted registry information does not provide an analyzed clinical outcome comparison from which to make either claim. The distinction is important: a study may have a defined question and a stated hypothesis while still lacking results capable of answering that question.
The record is most informative as an account of study design, enrollment, follow-up completion, termination status, and the absence of an outcome analysis. Any broader inference about treatment effects or safety would go beyond what the registry reports.
13. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the difference between a randomized design and an interpretable treatment-effect estimate. Randomization can help make groups comparable in expectation, but it does not itself generate an outcome result. The registry describes randomized allocation, yet reports no primary-outcome analysis and no WOMAC comparison.
Enrollment and follow-up completion also shape what the record can establish. Five patients enrolled, three were post-enrollment drop-outs, and two completed all follow-up visits. With no analysis reported, there is no estimate whose precision can be evaluated and no basis for judging how the observed data relate to the stated hypothesis. A design label cannot replace outcome data, and a hypothesis cannot be treated as a finding.
The record is also a useful example of why missingness and analysis-population details matter. The reasons for drop-out, endpoint data availability, treatment of missing observations, and intended analysis population are not reported. These details would be important for understanding any eventual comparison, but should not be filled in by assumption.
Finally, the safety counts show why a zero count in a small enrolled sample has a narrow interpretation. It records no affected participants in the listed event categories for the participants at risk, but offers no precise estimate of event likelihood and no evidence of equivalence between groups. The study's statistical contribution, as reported, is therefore chiefly descriptive of its design and limited conduct, rather than an estimate of comparative outcome effects.
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 for interpreting the study is that no analysis was done, according to the registry, because of the low number of patients. Five patients enrolled before termination, three were post-enrollment drop-outs, and two completed all follow-up visits. The record does not report WOMAC scores or results for any listed secondary outcome.
Important details about incomplete follow-up are absent. The reasons for drop-out, when it occurred, and whether endpoint measurements were collected are not reported. The registry does not describe how missing data would be handled, define an analysis population, or state whether any analysis would follow assigned treatment. As a result, even the availability of primary endpoint data for the participants completing follow-up cannot be established.
The study's termination status is reported, but the reason for termination is not separately given in the registry record. The primary outcome description connects the lack of analysis to the low number of patients; that does not establish every reason for the study's termination. The record also does not report a sample-size justification or a statistical analysis plan.
Methodological details are sparse beyond the labels randomized, single masked, and parallel. The randomization process, allocation concealment, identity of the masked party, endpoint scoring approach, and planned statistical model are not reported. The record does not describe multiplicity handling or sensitivity analyses. The listed safety counts are based on a very limited sample, and death counts are not reported. Together, these omissions prevent an assessment of comparative efficacy, precision, and broader safety from the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Dynamic Locking Screws 5.0 vs. Standard Locking Screws in Fracture of Distal Femur Treated With Locked Plate Fixation — NCT01693367.
- Registry record last updated 2020-08-13; status last verified 2016-08.
- Results first posted 2016-07-01.
- 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
NCT01693367 is a Phase 4 randomized, single-masked, parallel pilot study comparing ORIF with DLS 5.0 against ORIF with SLS for distal femur fractures treated with locked plate fixation. The registry lists the sponsor as AO Innovation Translation Center, a start date of 2012-09, a primary completion date of 2014-12, and a status of terminated.
WOMAC at 12 months after surgery was the primary outcome, intended to assess pain, stiffness, and physical function. Five patients enrolled, three were post-enrollment drop-outs, and two completed all study follow-up visits. The registry states that no analysis was done because of the low number of patients. No primary or secondary outcome results are reported. Serious and other adverse-event entries list zero affected participants in each group; death counts are not reported.