Protonics Knee Brace Versus Hamstring Resisted Exercise (HRE) on Individuals With Patellofemoral Pain Syndrome: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Protonics Knee Brace Versus Hamstring Resisted Exercise (HRE) on Individuals With Patellofemoral Pain Syndrome (NCT03042559), a randomized na study. The primary outcome is Anterior Pelvic Tilt.

2. Clinical Question

The registry describes a randomized controlled trial, with two parallel groups and no masking. It lists enrollment as 43. The posted arm summaries include 21.0 participants for Protonics Knee Brace and 20.0 for Sport Cords. The question is therefore a comparison between two assigned rehabilitation approaches, not a comparison with no treatment or usual care.

The clinical question and the primary posted outcome are not identical in scope. The brief summary describes a comparison concerning knee pain and function, whereas the named primary endpoint is a measure of pelvic position. The registry record does not report a primary pain or function measure among the result details. This distinction matters when interpreting what the reported numerical comparison can address: it concerns the recorded pelvic-tilt measure, not every aspect of pain, function, or rehabilitation.

The record identifies the condition and interventions but does not report enough eligibility, recruitment, or participant-characteristic detail to establish how broadly the results might apply. The target question is limited to the two interventions and the recorded population, setting, outcome, and follow-up described in the registry.

3. Trial Design

This was a randomized, parallel-group trial listed as completed. The registry gives a start date of 2017-02-14 and a primary completion date of 2018-01-08. Enrollment is listed as 43. The sponsor is Loma Linda University. The phase is recorded as NA, which is consistent with a rehabilitation-device comparison rather than a drug-phase classification.

Participants were assigned to Protonics Knee Brace or Sport Cords. The brace arm description says participants were fitted with a regular-sized brace, with settings to resist knee flexion. The comparator description says participants used a resistive sports cord to resist knee flexion. Both interventions therefore involve resistance to knee flexion, though they use different equipment. The registry title names hamstring resisted exercise, while the intervention and arm names use Sport Cords. The record does not provide further details about exercise instructions, treatment frequency, adherence, or co-interventions.

Masking is listed as none. This means the registry does not describe a masked trial; it does not establish whether outcome assessors were masked separately, because that detail is not reported in the registry record. The parallel model indicates that the assigned groups were compared alongside one another rather than using a crossover structure.

The primary outcome is anterior pelvic tilt, measured in degrees. Its timeframe is described as baseline to post-intervention, with the measurement interval specified as four weeks. The primary result summaries list mean values and standard deviations by arm. The registry also includes secondary outcome summaries, but the entries available for those measures are labeled baseline. The registry record does not report a fuller schedule of assessments or explain the analysis populations for each result.

The listed primary statistical analysis is Wilcoxon (Mann-Whitney), but no associated test statistic, p-value, estimate, or confidence interval is entered. The unadjusted mean difference and interval discussed elsewhere are recalculations from posted summary statistics, not the result fields for that listed test. The trial's original design assumptions, allocation ratio justification, and sample-size justification are not reported in the registry record.

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

Reasons for not completing this period:

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.

6. Primary Endpoint

The registry lists the primary outcome as Anterior Pelvic Tilt, measured over Baseline to Post intervention.

Anterior pelvic tilt describes the forward or anterior orientation of the pelvis. The registry says it was assessed with a CHEK inclinometer while participants stood. The examiner identified the anterior superior iliac spine and posterior superior iliac spine as the two measurement landmarks, placed the inclinometer caliper arms at those points, and recorded the angle in degrees.

The endpoint is specified from baseline to post-intervention, with the interval described as four weeks. A measure taken at two time points can be used to assess whether pelvic tilt changes over an intervention period and whether the recorded change differs between assigned groups. The registry's rationale describes comparing the observed angle with normative values from another study: 9° for males and 12° for females. Those reference values are context for the measure, not outcomes of this trial, and the registry does not report how the comparison with those reference values was used in analysis.

Pelvic position is a physical measurement rather than a direct measure of pain or daily function. The trial's brief summary mentions knee pain and function as areas of interest, but the primary endpoint listed in the results is anterior pelvic tilt. Accordingly, a difference in this measure would describe the recorded angle or its baseline-to-post-intervention summary; on its own, it would not establish a corresponding difference in pain or function.

The posted summaries give the endpoint as a mean with a standard deviation for each arm. The registry record does not provide detail about measurement reliability, assessor training, or the clinical importance of a particular difference in degrees. Without those details, statistical comparison and clinical interpretation should remain distinct.

7. Results Posted in the Registry

• Sport Cords: mean 3.20 versus 5.00 on control; difference -1.80 (95% CI -3.51 to -0.09), standardized effect d = -0.64; z-test p = 0.040.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Iliotibial Band Flexibility

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Sport Cords: mean 3.20 versus 3.50 on control; difference -0.30 (95% CI -1.95 to 1.35), standardized effect d = -0.11; z-test p = 0.722.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sport Cords and the control. The interval gives the range of effects that remain compatible with the data.

Hip Internal Rotation ROM

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Sport Cords: mean 28.80 versus 25.90 on control; difference 2.90 (95% CI -1.39 to 7.19), standardized effect d = 0.41; z-test p = 0.185.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sport Cords and the control. The interval gives the range of effects that remain compatible with the data.

Hip External Rotation ROM

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Sport Cords: mean 31.30 versus 31.30 on control; difference 0.00 (95% CI -3.00 to 3.00), standardized effect d = 0.00; z-test p = 1.000.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sport Cords and the control. The interval gives the range of effects that remain compatible with the data.

The posted secondary summaries cover measures of iliotibial band flexibility and hip rotation range of motion. The available result entries are labeled baseline, rather than a change from baseline to post-intervention. They therefore describe group values at baseline and should not be read as evidence that either intervention changed these measures over time.

The pattern across these baseline summaries is mixed: some group means are close, while another measure shows a larger separation. The corresponding unadjusted comparisons also vary in their estimates and uncertainty. This is descriptive context about the groups and the posted baseline values; it does not establish an intervention effect. The secondary entries do not provide a consistent basis for extending the primary comparison to other aspects of movement or flexibility.

These measures relate to the primary result because they describe other physical characteristics that may be relevant to a rehabilitation study, but they are not substitutes for anterior pelvic tilt. Nor do baseline differences explain the primary comparison without a reported adjusted analysis. The registry does not provide enough information to determine whether secondary outcomes were selected in advance, whether the analyses were planned as confirmatory, or how their timing relates to the primary endpoint.

Unadjusted secondary results carry less weight when multiple outcomes are examined. In general, each additional test creates another opportunity for an apparently unusual result to occur by chance. A multiplicity plan, such as a prespecified hierarchy or adjustment, can account for this issue, but none is reported in the registry record. The record also lists outcome measures beyond the secondary results posted, so the full analysis and reporting process cannot be reconstructed from the available entries.

These secondary results are best treated as exploratory descriptive information. They can motivate questions for further study, but they do not confirm the primary result, resolve its uncertainty, or establish a broader pattern across pain, function, and movement outcomes.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Iliotibial Band Flexibility
• Iliotibial Band Flexibility
• Iliotibial Band Flexibility
• Iliotibial Band Flexibility
• Hip Internal Rotation ROM
• Hip Internal Rotation ROM
• Hip Internal Rotation ROM
• Hip Internal Rotation ROM

9. Statistical Interpretation

10. Statistical Methods Explained

The registry labels the trial randomized, with a parallel model and no masking. Random allocation is intended to create groups that are comparable on average at the time of assignment, including with respect to measured and unmeasured characteristics. In an individual trial, randomization does not guarantee that the groups will be identical, particularly when the groups are small. The registry record does not describe sequence generation or allocation concealment, so those implementation details cannot be assessed from the reported information.

What does the listed Wilcoxon analysis test?

The registry names Wilcoxon (Mann-Whitney) as the reported analysis for the primary comparison. In general, this rank-based method compares the distribution of observations between two independent groups by ranking the pooled values. It does not require the same assumptions as a comparison of means under a normal model. Depending on the shapes of the two distributions, its result may reflect differences in location, spread, or other distributional features; it is not automatically a test of a difference in means.

For this trial, the registry's analysis result fields for that method are empty. The listed method therefore tells readers which test was named, but not what that test found. There is no reported test statistic, p-value, effect estimate, or interval for the Wilcoxon analysis in the record. The mean difference discussed in the interpretation is a simple unadjusted recalculation from the posted group summaries. It answers a mean-based question and should not be presented as though it were the missing rank-test result.

How should the mean summaries be understood?

A mean is the arithmetic average of a continuous measurement. A standard deviation describes how dispersed individual measurements are around the mean; it is not the standard error of the mean and not a confidence interval. The registry posts group means and standard deviations for the primary measure. The comparison calculation uses those summaries to express the difference in group means and estimate uncertainty under an unadjusted approach.

That approach summarizes the observed groups without covariate adjustment. It does not account for baseline characteristics, repeated measurements, missing outcomes, or any analysis choices not represented in the posted summaries. The record does not say whether the original analysis adjusted for baseline values or other covariates. It also does not clarify the precise form of the posted primary values, so the calculation cannot resolve whether they represent follow-up values or change from baseline.

What does a confidence interval communicate?

In general, a confidence interval is a range of estimates compatible with the data and the method used to calculate it. A narrower interval indicates greater precision under that method; a wider interval indicates more uncertainty about the size of the effect. An interval is not a guarantee that the true value lies within its limits, and its interpretation depends on the procedure and assumptions used to construct it.

The recalculated interval for the primary mean difference is -3.515 to -0.085. The registry does not state the confidence level for this interval. It should therefore be described by its reported limits without assigning an unreported coverage level. The interval accompanies the recalculated mean difference; it is not the missing confidence interval from the named Wilcoxon analysis.

Why can distribution shape matter?

General statistical methods often rely on assumptions about how observations vary. Mean-based methods focus on averages and may be sensitive to extreme values. Rank-based methods work with the ordering of observations and can be useful when distributional assumptions for a mean comparison are uncertain. Neither approach is universally preferable: the choice depends on the scientific estimand, the data distribution, the study plan, and the assumptions that can reasonably be defended.

Over-dispersion is a general issue in settings where a model assumes less variability than the data contain. When variability is greater than assumed, standard errors can be too small and intervals too narrow unless the analysis accounts for it. The endpoint is continuous, and the registry provides standard deviations, but it does not report a distributional assessment or an over-dispersion analysis. This general concept should not be mistaken for a documented problem in this trial.

What can the secondary analyses add?

The secondary result summaries are also means and standard deviations, with recalculated unadjusted comparisons where available. These comparisons can describe additional measured features, but they do not make the primary endpoint more precise. If many outcomes are examined, some results can appear noteworthy by chance even when no clear pattern exists. A prespecified testing hierarchy or multiplicity adjustment can help control that risk. Such a plan is not reported in the registry record, and the recalculated secondary p-values are unadjusted.

The registry lists 28 outcome measures and 2 analyses, while 12 secondary results are posted. The record does not explain how those counts relate to the choice of endpoints or analyses. It does not report the protocol, analysis plan, interim analyses, or rules for selecting results for posting. Those omissions prevent a full assessment of whether the displayed comparisons were prespecified or how the overall family of tests was handled.

Statistical significance and clinical importance are separate questions. A p-value describes compatibility between data and a statistical null under the method's assumptions; it does not measure the probability that an intervention is beneficial or the size of a clinically meaningful effect. The registry does not give a threshold for meaningful change in pelvic tilt. Interpretation should therefore focus on the actual estimate, its uncertainty, the outcome's relevance, and the limits of the record rather than on a p-value alone.

11. Confidence Intervals and Precision

The recalculated mean difference for the primary measure is -1.8 degrees, with a confidence interval from -3.515 to -0.085. The interval conveys uncertainty about the magnitude of the mean difference under the recalculation method. Its limits are both negative, but one lies close to zero, so the data are compatible with a small difference as well as a larger difference in the negative direction. The registry record does not report the confidence level attached to this interval.

Precision is not the same as accuracy. A confidence interval can be narrow while reflecting bias, or wide while still being centered on an unbiased estimate. Here, the record does not report enough about missing observations, allocation concealment, outcome assessment, or the exact definition of the posted primary summary to evaluate all possible sources of bias. The interval addresses sampling uncertainty under its calculation, not every limitation in trial conduct or reporting.

The recalculated unadjusted p-value is 0.04. It should be read alongside the estimate and interval rather than as a measure of effect size. The p-value does not say how likely the result is to replicate, nor does it tell whether a difference is clinically important. The registry's named Wilcoxon analysis has no reported result, and the interval belongs to the mean-based recalculation rather than that rank-based analysis.

The posted arm summaries have standard deviations of 2.8 in each group. These values describe dispersion among observations, whereas the confidence interval describes uncertainty in the estimated comparison. The record does not provide individual-level data, so readers cannot inspect distributions, outliers, or alternative summaries directly.

Overall, the interval gives a range of plausible estimates under a simple unadjusted calculation, but the lack of a reported confidence level and the missing result for the named analysis constrain how fully its precision can be evaluated.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size figures are planning illustrations based on the observed effect, not the trial's original design calculation. The registry record does not report the trial's own sample-size justification or original design assumptions. The displayed planning quantities are participants per arm, not total events. The calculation assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect set to the stated fraction of the observed effect.

The column for 80% power represents a planning scenario in which a future study would have an 80% chance of detecting the specified effect if that effect were truly present, under the calculation assumptions. The 90% power column uses a higher chance of detection under the same general framework. These are design probabilities, not guarantees about what a study will find. They depend on the assumed effect, variability, test, and other design choices.

Entries are shown for planning for 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect. For example, planning for 75% of the observed effect gives 68 participants per arm for 80% power and 91 participants per arm for 90% power. Planning for 50% of the observed effect gives 152 participants per arm for 80% power and 204 participants per arm for 90% power. The 100% scenario gives 38 participants per arm for 80% power and 51 participants per arm for 90% power.

Smaller effects are harder to distinguish from random variation, so planning for a smaller effect requires more participants. The planning values are not observed power: they do not measure the probability that the completed trial detected its effect. They are illustrations based on a range of assumed target effects using the observed estimate, which itself is uncertain. A new study's design should use a justified target effect and assumptions appropriate to its intended analysis.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -1.800; pooled standard deviation σ = 2.800.
2. n = 2 × (1.96 + 0.842)² × 2.800² / -1.800² = 38.0, rounded up to 38 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -1.8                      # observed difference in means
sigma <- 2.8                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(3042559)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 38 (80% power), 51 (90% power)
 75% of observed effect: n per arm = 68 (80% power), 91 (90% power)
 50% of observed effect: n per arm = 152 (80% power), 204 (90% power)
power.t.test: 39 
Simulated power at n = 38 per arm: 0.796 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when investigators test or estimate effects for several outcomes, time points, subgroups, or analysis choices. If each comparison is interpreted on its own without accounting for the full set of questions, the chance of at least one apparently notable result can increase. This does not mean every unadjusted result is invalid; it means its evidential weight depends partly on how many comparisons were planned and how they were selected and interpreted.

The registry lists 28 outcome measures and 2 analyses, and it includes 12 posted secondary results. It does not report a multiplicity adjustment, a testing hierarchy, or a distinction between confirmatory and exploratory outcomes. The record does not explain the relationship between the listed outcome measures and the posted analyses. Consequently, the primary recalculated p-value and the secondary recalculated p-values should be regarded as unadjusted. The registry also does not state whether outcomes or analyses were changed after study start.

Missing-data handling is not reported in the registry record. The results list arm-specific numbers for the posted summaries, but do not explain whether all randomized participants contributed to each analysis, how unavailable measurements were handled, or whether any imputation was used. The analysis populations are not reported in the registry record. It is therefore not possible to determine whether the results follow an intention-to-treat approach, a per-protocol approach, or another population definition.

Other important analysis details are also absent. The record does not report baseline adjustment for the primary comparison, a prespecified model, an interim-analysis plan, or a protocol-level statistical analysis plan. It names Wilcoxon (Mann-Whitney) but provides no result for that analysis. The mean-based recalculations do not fill those gaps; they offer a separate summary based on posted group statistics.

These omissions limit the assessment of selective reporting, analysis choices, and the robustness of the reported comparisons. They do not show that analyses were mishandled; they mean the registry record does not provide the information needed to evaluate those questions.

15. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry reports zero serious adverse events for Protonics Knee Brace and zero for Sport Cords. It also reports zero other adverse events in both groups and zero deaths in both groups. The listed numbers at risk are 21 for Protonics Knee Brace and 20 for Sport Cords for the serious-event and other-event summaries. No serious adverse-event terms are listed.

These entries indicate that the registry reports no affected participants in the listed adverse-event categories during the recorded study period. They should be interpreted together with the numbers at risk and the trial's size and follow-up. A zero in a registry result does not prove that an event is impossible or that no event occurred outside the way events were defined, collected, or reported. The record does not describe the adverse-event collection procedures, event definitions, monitoring schedule, or the duration of safety follow-up.

The safety figures are descriptive counts, not a formal comparison of risk. With no reported events in either group, the registry entries do not estimate a relative difference in event rates. They also do not address tolerability, adherence, or other outcomes unless these were captured as adverse events. The record should be read as reporting no serious or other adverse events and no deaths in the listed groups, rather than as establishing a general safety profile.

16. What the Result Does, and Does Not, Mean

The posted result supports a limited statistical statement: the recalculated unadjusted mean difference in anterior pelvic tilt favors a lower mean in the Sport Cords group under the subtraction order used, with an estimate of -1.8 degrees and an interval from -3.515 to -0.085. The associated unadjusted p-value is 0.04. These are summaries of the posted data, not a complete report of the analysis named in the registry.

The registry's reported analysis is Wilcoxon (Mann-Whitney), but its result is not entered. The mean-based estimate and interval are recalculations from the available summary statistics and cannot be substituted for the missing result of that analysis. The confidence level for the recalculated interval is also not reported. Those details limit how definitive an interpretation can be.

The result does not establish that the brace or Sport Cords improves knee pain or function. Although pain and function appear in the trial's brief objective, the primary outcome result listed is anterior pelvic tilt. The record does not provide a corresponding primary numerical comparison for pain or function. A difference in pelvic tilt does not, by itself, indicate how participants felt or functioned, nor whether a change would matter to them.

The results also do not establish superiority across the full set of outcomes or a general effect for all people with patellofemoral pain syndrome. The record does not describe important features such as adherence, missing-data handling, participant characteristics, or a multiplicity plan. The secondary summaries are labeled baseline, so they do not demonstrate post-intervention changes in those measures.

Interpretation should distinguish the numerical estimate from its clinical meaning and from the quality of the evidence. The estimate is uncertain, the named analysis result is unavailable, and the record does not give a threshold for a meaningful change in degrees. The trial can inform questions about comparing these interventions on the recorded measure, but the registry results alone do not settle broader questions about benefit, function, or comparative effectiveness.

17. Why This Trial Matters Statistically

This trial is statistically instructive because its registry record presents a gap between a named analysis and the numerical summaries available for interpretation. The reported analysis is Wilcoxon (Mann-Whitney), but its result fields are blank. A mean difference and confidence interval can be recalculated from the posted means, standard deviations, and group sizes, but that calculation answers a different statistical question from the rank-based test. Keeping the two analyses distinct prevents a recalculation from being mistaken for the trial's reported test.

The example also illustrates why an estimate should be read with its uncertainty. The primary mean difference is accompanied by an interval that approaches zero at one limit. Reporting the point estimate alone would hide that uncertainty, while reporting only the p-value would obscure the size and direction of the comparison. The record does not report the interval's confidence level, another reason to describe precisely what is available rather than overstate the inference.

Multiplicity is relevant because the registry lists multiple outcome measures and posts secondary comparisons. An isolated unadjusted result can have a different evidential meaning from a result selected in a prespecified testing plan. The registry does not report such a plan, so the primary and secondary comparisons cannot be interpreted as a fully controlled family of tests.

The record further highlights how outcome choice shapes interpretation. The stated objective refers to knee pain and function, but the primary posted endpoint is anterior pelvic tilt. Statistical evidence about a physical angle is not automatically evidence about symptoms or function. Clear alignment among the scientific question, endpoint, analysis, and reported result is important for readers deciding what a trial can answer.

Finally, planning illustrations based on an observed effect are not a replacement for an original sample-size rationale. They can show how sample-size requirements change with a target effect, but the original design assumptions are not reported. This distinction helps keep planning scenarios separate from evidence about the completed trial.

18. 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.

Several limitations are specific to the available record. First, the brief objective concerns knee pain and function, but the primary result listed is anterior pelvic tilt. The numerical outcome therefore does not directly answer all parts of the stated clinical objective. The registry record does not provide a primary numerical result for pain or function.

Second, although the primary timeframe is described as baseline to post-intervention over four weeks, the result fields do not clarify whether the posted arm means are post-intervention values, changes from baseline, or another summary. That ambiguity limits interpretation of the mean difference as a change. The secondary measures are labeled baseline, which makes them unsuitable for conclusions about intervention-related change.

Third, the named Wilcoxon (Mann-Whitney) analysis has no reported estimate, p-value, or interval. The available mean-based comparison is a recalculation and may not represent the analysis used for the trial's reported conclusion. The confidence level for the recalculated interval is not reported.

The record does not report detailed eligibility criteria, baseline participant characteristics, intervention frequency, adherence, assessor masking, allocation concealment, missing-data handling, or analysis populations. It also does not report a statistical analysis plan, a multiplicity procedure, or the original sample-size justification. These gaps restrict assessment of generalizability, risk of bias, selective reporting, and robustness.

Finally, the posted safety counts are limited to the reported adverse-event categories and follow-up described in the record, which is not detailed. The absence of reported events should not be generalized beyond those registry entries. Together, these limitations mean the results are informative as a record of a small randomized comparison, but the available reporting does not support broad conclusions about clinical outcomes or the full conduct of the trial.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Protonics Knee Brace Versus Hamstring Resisted Exercise (HRE) on Individuals With Patellofemoral Pain Syndrome — NCT03042559.
• Registry record last updated 2020-05-15; status last verified 2020-04.
• Results first posted 2019-11-22.
• 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.

22. Record Summary

NCT03042559 is a completed randomized, parallel-group trial sponsored by Loma Linda University. It compared a Protonics Knee Brace with Sport Cords in people with patellofemoral pain syndrome. Enrollment is listed as 43, masking as none, and the primary completion date as 2018-01-08.

The primary outcome was anterior pelvic tilt, measured in degrees from baseline to post-intervention, with the interval described as four weeks. Posted means were 5.0 for Protonics Knee Brace and 3.2 for Sport Cords. The recalculated unadjusted mean difference was -1.8, with a confidence interval from -3.515 to -0.085 and an unadjusted p-value of 0.04. The registry names a Wilcoxon (Mann-Whitney) analysis but does not report its result.

Secondary entries are labeled baseline. Serious and other adverse events and deaths are recorded as zero in both groups. The registry does not report the original sample-size rationale, multiplicity plan, missing-data handling, or analysis populations. The results should be interpreted as limited evidence about the posted endpoint and record, not as a complete account of effects on pain or function.