Proprioception of the Knee Post MIS TKA and MIS-QS TKA: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Proprioception of the Knee Post MIS TKA and MIS-QS TKA (NCT02160977), a randomized na study. The primary outcome is Proprioception of the Knee Post Operation.

2. Clinical Question

The study’s stated rationale is that earlier recovery of proprioception might accompany recovery of motion control ability and accuracy. That rationale describes the motivation for comparing the procedures; it is not evidence that either procedure produced earlier recovery. The endpoint is a knee angle reproduction test, with higher values described as a worse outcome. Without the reported measurements, it is not possible to tell whether recorded position-sense values changed over time, whether the groups differed at any assessment, or how precisely any difference was estimated.

The record also lists the Hospital for Special Surgery (HSS) Score of the Knee Joint and the Visual Analogue Scale (VAS) of the Knee Joint as secondary outcomes. Their results are not reported in the registry record. Consequently, the registered question can be described, but the posted information does not support a conclusion about the comparative outcomes of the procedures.

3. Trial Design

The registry describes a prospective, randomized, double-masked, parallel-group comparative study. It lists an enrollment of 90 and an overall status of completed. The record identifies osteoarthritis as the condition and total knee arthroplasty as the procedure. The listed sponsor is Jia-kuo yu. The study start is recorded as 2011-10, and primary completion as 2012-06.

Participants were assigned to one of two procedure groups: MIS-QS TKA, described as minimally invasive surgery quadriceps-sparing total knee arthroplasty, or MIS TKA, described as minimally invasive surgery total knee arthroplasty. The registry labels allocation randomized, masking double, and the model parallel. It does not describe how the random sequence was generated, how assignment was concealed, or which people were masked. Those implementation details are not reported in the registry record, so the labels alone cannot establish how these processes were carried out.

The primary outcome is titled “Proprioception of the Knee Post Operation.” Its assessment is described as a knee angle reproduction test, performed before operation and at 1 week, 6 weeks, 3 months and 6 months after operation. The primary outcome timeframe is listed as six months. HSS and VAS scores are listed as secondary outcomes. The record lists 3 outcome measures and 3 analyses, but does not provide the analysis descriptions or outcome estimates in the information available for this account.

The listed enrollment and the groups described in the adverse-event record are separate registry entries. The adverse-event record lists 42 at risk in each group; the record does not explain how those entries relate to enrollment or to the populations used for efficacy analyses. The phase is listed as NA. Further eligibility criteria, recruitment details, the sample-size justification, and the planned statistical analysis 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.

Before assignment: Patients refused to receive MIS-QS TKA or MIS TKA.

One Week After Surgery

Six Weeks After Surgery

Reasons for not completing this period:

Three Months After Surgery

Reasons for not completing this period:

Six Months After Surgery

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 Proprioception of the Knee Post Operation, measured over six months.

The primary endpoint assesses knee position-sense proprioception using a knee angle reproduction test. Participants were assessed before operation and at 1 week, 6 weeks, 3 months and 6 months post operation. The test is described at knee flexion ranges of 10~20 degree, 30~40 degree, and 80~90 degree. Its scale is described as a degree scale with a range of 0~180 degree, and higher values represent a worse outcome.

In general, an angle reproduction task can be used to assess how accurately a person can perceive and reproduce a joint position. It is relevant to a study of proprioception because it focuses on position sense rather than relying only on a general report of pain or function. Repeated assessments can describe the course of measured position sense over follow-up, provided the results and analysis are reported.

The registry specifies the outcome parameter as a mean and its dispersion as Standard Error. A mean describes the average recorded value, while a standard error describes the precision of an estimated mean; it is not the same as the spread of individual observations. The record does not report the means, standard errors, group contrasts, or confidence intervals. Therefore, the endpoint definition explains what was measured and how to orient its direction, but not what the study found.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry’s statistical information is limited. It identifies the primary outcome as a mean of a continuous measure, with Standard Error as the dispersion measure. It also describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It does not report the trial’s statistical analysis plan or the outcome estimates needed to evaluate the comparison.

What does a mean represent?

In general, a mean is an average of measured values. For the knee angle reproduction test, the mean would summarize the recorded scale values for a group at a specified assessment. The endpoint description says that higher values represent a worse outcome, so direction matters when interpreting any reported mean: a higher value would correspond to worse measured proprioception under the registry’s definition. The registry record does not give the group means, so it is not possible to apply that direction to an observed comparison.

What does Standard Error tell the reader?

In general, a standard error describes the precision of an estimate such as a mean. It reflects uncertainty around the estimated average, rather than directly describing how much individual participants’ measurements vary. A standard error can help readers assess how precisely a group mean has been estimated, but it is not by itself a complete description of a treatment contrast. No standard errors are reported in the registry record, and no confidence intervals are reported.

In general, a confidence interval gives a range of values compatible with the data and the statistical method used. Its width communicates uncertainty: a narrower interval indicates greater precision than a wider one, all else equal. The interval also helps readers judge which effect sizes remain plausible. Because no confidence intervals or group contrasts are reported for this endpoint, the precision of the comparison cannot be evaluated.

Why does the assessment schedule matter?

The registry describes repeated measurements: before operation and at 1 week, 6 weeks, 3 months and 6 months after operation. A repeated schedule can address both the measured level at particular assessments and how the recorded outcome changes over follow-up. Those are related but distinct questions. A comparison at one assessment does not by itself describe the pattern at other assessments, and a change over time within a group does not by itself establish a difference between groups.

Here the primary outcome has several categories or time points, and the record does not reduce them to a single comparison. It does not report whether the analysis compared groups separately at each assessment, modeled the repeated measurements together, adjusted for baseline values, or used another approach. Those analysis details are not reported in the registry record. Thus readers cannot determine which estimate, if any, was designated as the principal comparative test.

What do the planning assumptions mean?

The registry describes planning illustrations using a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. In general, a significance level is a threshold used by a statistical testing procedure to assess evidence against a null hypothesis. A two-sided procedure allows evidence in either direction to count against that hypothesis. These assumptions describe the planning illustrations; they do not establish the analysis used for the completed trial.

The illustrations are described as using a stated fraction of the observed effect. In general, planning for a smaller effect requires more information to detect it with a specified level of power, all else equal. Such calculated sample sizes are planning illustrations, not observed power and not evidence that a study achieved a particular result. The sample-size justification for this trial, its target effect, and any trial-specific power calculation are not reported in the registry record. The listed enrollment should therefore not be treated as proof of adequate power.

The registry states that the illustrations use equal allocation. That is an assumption for the calculations, not confirmation of the numbers included in the final outcome analyses. The adverse-event entry lists 42 at risk in each group, but the record does not say whether those are the analysis populations for the primary endpoint or how missing measurements were handled.

What cannot be recovered from the posted information?

General statistical interpretation of a randomized comparison depends on the estimated group difference, its uncertainty, and a clear account of how the data were analyzed. Here, the outcome estimates, confidence intervals, and test results are not reported in the registry record. The record also does not describe the statistical model, any adjustment variables, assumptions checks, handling of repeated observations, or treatment of missing data. Those omissions prevent a detailed appraisal of the analysis and do not justify assuming a particular method.

The registry lists 3 outcome measures and 3 analyses, but does not explain their correspondence or identify the full set of planned tests. A larger set of outcomes or assessment times can raise multiplicity concerns in general, because repeated testing can increase the chance of a chance-positive result if no adjustment or prespecification is used. Whether or how that issue was addressed in this study is not reported in the registry record. The listed planning assumptions do not answer that question.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is described at several assessment times and at multiple knee flexion ranges. The record explicitly indicates that the primary outcome has several categories or time points and has not been reduced to one comparison. HSS and VAS are also listed as secondary outcomes, and the registry lists 3 outcome measures and 3 analyses. It does not identify which outcome or time point was designated as the sole confirmatory comparison, nor does it describe a multiplicity adjustment. These details are not reported in the registry record.

In general, testing multiple outcomes, time points, or contrasts can increase the chance that at least one result appears statistically notable by chance. Prespecifying a primary comparison or using an appropriate adjustment can help address this issue. The record does not report whether such steps were part of the trial’s analysis. Without the outcome estimates and analysis description, the extent to which multiplicity affects interpretation cannot be assessed.

The record does not describe missing-data frequency, reasons for missing measurements, or methods used to handle missing observations. It also does not specify whether analyses followed an intention-to-treat population, a per-protocol population, or another analysis population. The listed at-risk groups in the adverse-event record do not establish which participants contributed to each efficacy analysis.

These omissions matter because repeated-measurement analyses can depend on how incomplete follow-up is handled, and different analysis populations can answer different questions. No approach should be inferred from the randomized, double-masked, parallel-group design alone. Missing-data procedures, analysis populations, and the multiplicity strategy are not reported in the registry record.

11. Safety Results

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

Other (non-serious) adverse events

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

The adverse-event record lists MIS-TKA and QS-TKA groups, with 42 at risk in each. It records 0 serious adverse events and 0 other adverse events for each listed group. These figures describe the event fields recorded in the registry; they do not provide a detailed account of event definitions, surveillance methods, or follow-up procedures.

In general, a recorded zero means that no events were entered for that category in the stated record. It does not prove that an event was impossible, that all potential harms were captured, or that groups have identical safety profiles. With no additional details about ascertainment or analysis, the counts should be read descriptively rather than as evidence of equivalence.

Deaths are shown as null in the record, so death counts are not reported in the registry record. The event entries do not establish how the listed at-risk groups relate to enrollment or to the populations used for other outcomes. The safety information therefore supports only a narrow statement about the entries: the registry lists zero serious and zero other events in both groups, while death counts and further safety details are not reported.

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

The record defines a randomized comparison of proprioception after MIS-QS TKA and MIS TKA and describes the knee angle reproduction test used to assess position sense. It also specifies that higher scale values represent a worse outcome and lists assessments from before operation through 6 months after operation. These details clarify the study question and the direction of the endpoint.

They do not establish which procedure had better measured proprioception, whether either group changed over time, or whether the groups differed. The primary outcome means, standard errors, comparative estimates, confidence intervals, and test results are not reported in the registry record. The secondary HSS and VAS results are also not reported. Consequently, the posted information cannot support a conclusion about the size, direction, or precision of the comparative outcomes.

The record’s rationale refers to the possibility that earlier proprioception recovery could accompany recovery of motion control ability and accuracy. That is a motivation for the study rather than a finding. The registry’s completed status also does not substitute for outcome reporting. The absence of results should not be interpreted as evidence of no difference, and it does not establish that the procedures are equivalent or that either one is superior.

Similarly, the adverse-event entries show zero serious and zero other events recorded in each listed group, while death counts are not reported. Those entries do not demonstrate that the procedures have identical safety profiles or that no unrecorded events occurred. They are limited registry counts and should not be extended beyond the categories and entries shown.

The most defensible reading is therefore a description of design and measurement, not an efficacy conclusion. The record tells readers what comparison was planned and how the primary outcome was defined, but the missing outcome estimates leave the clinical and statistical result unresolved.

13. Why This Trial Matters Statistically

This trial is statistically relevant because it uses a randomized, parallel-group design to compare two named TKA procedures on a specific measure of knee position sense. Random allocation can support a fair comparison when assignment, follow-up, and analysis are implemented and reported appropriately. The registry labels the study randomized and double-masked, but does not report the operational details needed to evaluate those processes fully.

The outcome is measured repeatedly, including before operation and at several post-operation assessments. Such a schedule makes the distinction between a single group difference and a recovery pattern important. A meaningful statistical account would identify the comparison being estimated, explain how repeated measurements were handled, and report the estimates with their uncertainty. The registry record does not provide those results or methods.

The case also illustrates why outcome definitions alone are not enough for statistical interpretation. The endpoint specifies a test, measurement ranges, scale direction, and a summary parameter. Yet without reported values, readers cannot judge the magnitude or precision of any observed difference. Nor can they determine whether the observed pattern was consistent across the assessment schedule.

Finally, the presence of several outcome measures and time points raises general questions about multiplicity, missing observations, and the analysis population. The registry record does not report how these issues were addressed. Its planning assumptions are not a substitute for an analysis plan or results. The main statistical contribution of the record as described is therefore to make the comparison and measurement framework identifiable while leaving the comparative evidence unavailable.

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 that the registry record does not report the primary outcome values or comparative analysis. Without group estimates, uncertainty intervals, or test results, readers cannot assess the direction, magnitude, or precision of the proprioception comparison. The secondary HSS and VAS results are also not reported.

The outcome is assessed across multiple flexion ranges and several times, but the record does not identify a single reported primary contrast. It does not explain how repeated observations were analyzed or whether comparisons were made at each assessment. Statistical methods, adjustment variables, assumptions checks, and handling of missing data are not reported in the registry record. The planned analysis population is also not stated.

Although the study is labeled randomized and double-masked, the record does not explain sequence generation, allocation concealment, or who was masked. Eligibility criteria, participant characteristics, and the relationship between the listed enrollment and the adverse-event entries are not described in the information available for this account. The group entries for adverse events therefore should not be treated as a complete description of the efficacy analysis populations.

The record does not report the sample-size justification, the study’s own statistical plan, or whether multiplicity was addressed. Planning illustrations based on an observed effect do not establish that the completed study was adequately powered. Safety reporting is also limited: the registry lists zero serious and zero other events in both groups, but deaths and further event-ascertainment details are not reported. These limitations restrict interpretation to the stated design and measurement descriptions, rather than comparative conclusions.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Proprioception of the Knee Post MIS TKA and MIS-QS TKA — NCT02160977.
• Registry record last updated 2014-08-04; status last verified 2014-07.
• Results first posted 2014-08-04.
• 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

NCT02160977 is listed as a completed, prospective, randomized, double-masked, parallel-group comparison of MIS-QS TKA and MIS TKA for osteoarthritis. The registry lists enrollment of 90, a study start of 2011-10, and primary completion of 2012-06. The primary outcome is knee proprioception assessed with a knee angle reproduction test before operation and at 1 week, 6 weeks, 3 months and 6 months after operation. Higher values are described as worse outcomes.

HSS and VAS scores are listed as secondary outcomes. The registry record does not report the primary or secondary outcome estimates, comparative tests, confidence intervals, analysis populations, missing-data methods, or multiplicity approach. The adverse-event entry lists zero serious and zero other events in each group, with death counts not reported. The record therefore establishes the study question and outcome framework but does not provide enough reported results to assess comparative outcomes.