Effects of Exoskeleton-Assisted Gait Training on Bone Health and Quality of Life: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effects of Exoskeleton-Assisted Gait Training on Bone Health and Quality of Life (NCT02533713), a randomized na study. The primary outcome is Change in Tibial Stiffness.

2. Clinical Question

3. Trial Design

The registry describes a randomized clinical trial with a crossover model and no masking. The trial record lists enrollment as 61 and status as completed. The sponsor is Craig Hospital. The recorded start date is 2017-06-23, and the primary completion date is 2021-12-10. The phase is listed as NA, which is not a drug-development phase designation for this device intervention.

Participants were assigned to immediate or delayed gait training. The immediate sequence began exoskeleton-assisted gait training right away and continued during the first 6 months. The delayed sequence did not gait train for 6 months and then trained during the last 6 months. In this arrangement, the delayed sequence serves as a period without training before it receives the intervention, while both sequences eventually train.

The primary endpoint timing is defined in relation to each sequence. For the immediate sequence, pre-training is baseline and post-training is 6 months after baseline. For the delayed sequence, pre-training is 6 months after baseline and post-training is 12 months after baseline. This timing is important: participants in the sequences are assessed at different calendar points relative to study entry, and the primary outcome is expressed as change around the training period.

The registry does not report the randomization procedure, allocation concealment, masking of outcome assessors, washout period, or detailed visit schedule. It also does not report how the crossover structure was incorporated into the analysis, including any treatment-period, sequence, or carryover terms. Those details matter for interpreting a within-person or sequence-based comparison, but cannot be inferred from the design label alone.

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: 1 participant consented and enrolled into the study but did not progress to randomization or complete any study activities (e.g. secondary screening, study testing).

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 Change in Tibial Stiffness, measured over Pre Gait Training (baseline for Immediate Gait Training Arm and 6 months post baseline for Delayed Gait Training Arm), Post Gait Training (6 months post baseline for Immediate Gait Training Arm and 12 months post baseline for Delayed Gait Training Arm).

The primary endpoint is change in tibial stiffness, expressed in g(^2)/cm(^4). The registry identifies the measure as a mean of a continuous outcome, with standard deviation as its stated measure of dispersion. It describes tibial stiffness as an epiphysis compressive strength index assessed by finite element analysis of a quantitative CT scan of the knee.

In general, a continuous endpoint can retain information about the degree of variation in a measured characteristic, rather than reducing participants to categories. A mean describes the average value in a group, while a standard deviation describes the spread of individual measurements around that average. These are descriptive summaries; without an estimated between-period or between-sequence difference and its uncertainty, they do not by themselves show the size or precision of a training-associated change.

The endpoint is used to assess a bone-related measure alongside other listed outcomes, including bone volume, mood, pain, cortical activity, and health-related quality-of-life domains. The record does not explain why tibial stiffness was selected over other measures, nor does it report a clinically meaningful threshold for interpreting a change. Most importantly, the registry record does not report the observed means, standard deviations, change estimate, or inferential result for this endpoint. Its measurement approach and timing are described, but the outcome finding is not.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General statistical explanation: randomization is intended to make assignment to treatment sequences independent of participants’ characteristics, on average. It can support a comparison of assigned strategies, but it does not guarantee that groups are identical or ensure that every randomized participant contributes complete outcome data. The registry states that allocation was randomized but does not report the randomization method or allocation concealment.

What does a crossover design imply?

General statistical explanation: in a crossover design, participants may receive an intervention at different periods, so measurements can be compared within a participant or across treatment sequences. Such designs can account for stable differences between participants when the analysis appropriately models repeated observations. They also require attention to changes over time, period effects, sequence effects, and possible carryover from an earlier treatment period. Whether these issues were relevant to this trial, and how they were handled, are not reported in the registry record.

The described schedules place immediate training in the first 6 months and delayed training in the last 6 months. The primary endpoint compares pre-training with post-training measurements at the corresponding times for each sequence. That structure gives context for the planned assessments, but does not tell readers whether the primary analysis used within-person changes, a between-sequence contrast, or another method. The analysis model and any adjustment variables are not reported in the registry record.

What do the mean and standard deviation describe?

General statistical explanation: the mean is the arithmetic average of measured values, and the standard deviation describes how spread out those values are around the mean. A mean change can summarize the direction and average magnitude of a continuous outcome change. A standard deviation describes variation among measurements; it is not itself a confidence interval and does not directly quantify uncertainty in the estimated mean. The record specifies mean and standard deviation for the primary outcome but does not post the resulting values.

General statistical explanation: a confidence interval gives a range of values compatible with the data under the chosen statistical method and conveys the precision of an estimate. A narrow interval indicates greater precision than a wide interval, but its interpretation depends on the design and assumptions. No confidence interval for tibial stiffness is reported in the registry record, so the precision of the trial’s primary result cannot be assessed.

How should statistical testing be read?

General statistical explanation: a p value describes how unusual data at least as incompatible with a null hypothesis would be under the assumptions of a specified test. It is not the probability that the null hypothesis is true, and it does not measure the size or practical importance of an effect. The registry record reports no primary outcome p value or test result. No test procedure or statistical model is reported.

The registry lists 9 outcome measures and 0 analyses. This distinction matters: an outcome measure indicates an outcome that was specified for assessment, whereas an analysis entry would describe results or analytical findings. The record does not provide numerical findings for the primary or secondary measures. Therefore, readers cannot infer whether any planned contrast was tested, whether tests were adjusted, or whether an outcome was omitted from analysis.

What does the sample-size illustration represent?

The registry describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect. For non-time-to-event outcomes, any such illustration is expressed as participants per arm for 80% or 90% power. These are planning assumptions, not evidence about the trial’s actual power, and they are not the trial’s own design justification. No numerical planning values or effect estimate are reported in the registry record. The record also does not report the original sample-size justification, so the illustration cannot substitute for it.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 9 outcome measures: the primary measure of change in tibial stiffness and secondary measures covering bone volume, mood, pain, cortical activity, and four health-related quality-of-life domains. It lists 0 analyses. No outcome estimates or inferential results are reported in the registry record.

General statistical explanation: when several outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase if each test is interpreted separately. A prespecified approach to multiplicity can clarify which comparisons are confirmatory and how uncertainty is handled across them. The registry record does not report a multiplicity adjustment, a hierarchy of outcomes, or which analyses were considered primary or exploratory beyond naming the primary outcome.

The record also does not report missing-data counts, reasons for missingness, methods for handling incomplete measurements, or the number of participants included in any analysis. Enrollment of 61 is not an analysis denominator. An analysis population definition, such as whether all randomized participants were included or whether a subset with complete observations was used, is not reported in the registry record.

For a crossover trial, the handling of incomplete periods and participants who did not complete both training periods can affect interpretation. The registry record does not report completion by sequence, period-specific availability, imputation methods, or sensitivity analyses. Without these details, it is not possible to judge how missing data may have affected the estimated outcome or whether the results would be robust to alternative assumptions.

11. 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.

Most frequent non-serious adverse event terms

The serious adverse event entries list 0 affected among 13 at risk in the Immediate Gait Training group and 0 affected among 6 at risk in the Delayed Gait Training group. Deaths are listed as 0 in both groups. These are the figures recorded for the groups shown; they are not a complete description of all possible harms or of the timing and duration of safety monitoring.

For other, non-serious adverse events, the registry lists 13 affected among 13 at risk in the Immediate Gait Training group and 6 affected among 6 at risk in the Delayed Gait Training group. These entries indicate participants affected, as recorded, and should not be read as a count of separate events. The record does not supply the event terms, severity details, relationship to the intervention, exposure time, or definitions used for these categories.

The figures are group-specific registry entries and should not be treated as the trial’s overall safety profile. The record does not explain how safety information was collected, how crossover periods were assigned to adverse-event groups, or whether reporting was complete for every participant. Zero serious events recorded does not establish that no harm occurred; it describes only what the registry entries report.

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

The trial addresses a question about whether exoskeleton-assisted gait training is associated with a change in a measured bone-related outcome, tibial stiffness, in a population listed as having osteoporosis. Its randomized crossover structure and defined pre-training and post-training assessment periods describe how the investigators intended to study the question. The registry also lists additional musculoskeletal, mood, pain, cortical activity, and quality-of-life outcomes.

Those design features do not supply an answer by themselves. The registry record reports no outcome analyses and no numerical results for tibial stiffness or the secondary outcomes. There is therefore no posted estimate to interpret as an increase, decrease, or absence of change, and no confidence interval with which to judge precision. The record cannot establish the magnitude or direction of any observed association.

Even a reported change in tibial stiffness would describe a measured endpoint, not automatically a meaningful change in health or quality of life. The registry does not state a clinically important threshold for the measure. Nor does it report results linking tibial stiffness changes to fractures, functional outcomes, or other clinical events. No such relationship should be inferred from the endpoint name or measurement method.

The record’s enrollment entry is not a substitute for knowing how many participants contributed measurements to each analysis. The number analyzed, missing-data handling, and the model used for the crossover are not reported in the registry record. These omissions limit assessment of both the result and its generalizability.

The appropriate conclusion is therefore narrow: the registry identifies a completed randomized trial and its planned outcome framework, but it does not report the findings needed to determine what the trial observed. Absence of posted results is not evidence of benefit, lack of benefit, or equivalence.

13. Why This Trial Matters Statistically

This trial is statistically notable because the study combines random assignment with a crossover schedule. Such a design can make the timing of measurements central to interpretation: the immediate and delayed sequences encounter training in different study periods. A clear account of how repeated measures, period, sequence, and possible carryover are handled is especially relevant, but those analytical details are not reported in the registry record.

The primary measure is a continuous imaging-derived index, rather than a simple event count. Reporting its mean change, variability, and uncertainty would help readers understand both the estimated change and how precisely it was measured. The registry defines the assessment method and timing, yet provides no analysis results. This gap illustrates why a precise outcome definition and a completed-trial status do not replace posted results.

The record also lists several secondary outcome areas. When multiple outcomes are assessed, readers need to know which findings were prespecified, how multiplicity was considered, and how missing observations were handled. The registry does not report these analysis details and lists 0 analyses. Without them, neither outcome-specific conclusions nor an assessment of selective reporting can be made from the record.

Finally, the registry’s planning illustration is distinct from the trial’s own design justification and from observed power. It describes assumptions for hypothetical planning based on the observed effect; it does not provide evidence that the trial was adequately powered for its primary question. Since no outcome estimate is reported, the record offers no basis for judging the precision achieved. The statistical importance of this trial record lies in the contrast between a clearly named design and endpoint and the absence of posted outcome analyses.

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 of the registry record is that it does not report primary or secondary outcome analyses. Although the trial is marked completed, the record lists 0 analyses. No effect estimate, standard deviation result, confidence interval, or p value is available for tibial stiffness. The direction, magnitude, and precision of the measured change therefore cannot be evaluated.

The design is identified as crossover, but the record does not describe the analysis model or how it handled the different training periods. It does not report a washout period, treatment-period effects, sequence effects, carryover assessment, or repeated-measure structure. These are not necessarily problems with the trial; they are unreported details that limit independent interpretation.

The record lists enrollment as 61 but does not state how many participants completed each period or contributed data to each outcome. It does not report exclusions, missingness, reasons for missing data, or analysis populations. Baseline characteristics and eligibility criteria are also not reported in the registry record, limiting description of the participants and assessment of how broadly the findings might apply.

Outcome measurement is described for tibial stiffness, but the record does not report the actual observed values or a clinically meaningful threshold. It also does not provide detailed information about assessor masking, despite listing no masking, or the reliability and reproducibility of measurements. The secondary outcomes are named without numerical findings or details of their analysis.

Finally, the safety entries do not include adverse-event terms, severity beyond the serious/non-serious categories, intervention relatedness, or monitoring windows. These limitations concern what the registry record reports and do not establish whether additional information exists outside it.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Effects of Exoskeleton-Assisted Gait Training on Bone Health and Quality of Life — NCT02533713.
• Registry record last updated 2026-09-02; status last verified 2026-08.
• Results first posted 2026-09-02.
• 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.

18. Record Summary

The registry record describes NCT02533713, a completed randomized crossover trial sponsored by Craig Hospital. The trial studied exoskeleton-assisted gait training, with immediate and delayed training sequences. Enrollment is listed as 61. The recorded study start date is 2017-06-23, and primary completion is recorded as 2021-12-10.

The primary outcome was change in tibial stiffness, measured as an epiphysis compressive strength index by finite element analysis of a quantitative CT scan of the knee. Secondary outcomes include bone volume, mood, pain, cortical activity, and health-related quality-of-life domains. The record lists 9 outcome measures and 0 analyses.

No primary or secondary outcome estimates, confidence intervals, or p values are reported in the registry record. Serious adverse events and deaths are recorded as 0 in each listed group; other adverse events are also reported by group. The outcome findings and the analysis details needed to interpret them remain unreported in the registry record.