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The validity and reliability of the Perometer in evaluating human knee volume
Ivy O W Man1, Kate L Markland, Matthew C Morrissey
1Centre for Applied Biomedical Research, GKT School of Biomedical Sciences, King's College London, St Thomas' Street, London SE1 1UL, UK.
Clinical Physiology and Functional Imaging
|November 4, 2004
Summary
An optoelectronic device, the Perometer, shows reliability comparable to water volumetry for knee swelling assessment. However, significant differences mean these methods for knee volume measurement should not be used interchangeably.
Area of Science:
- Biomedical Engineering
- Orthopedics
- Medical Imaging
Background:
- Accurate knee swelling evaluation is crucial for patient monitoring and rehabilitation.
- Water volumetry, the gold standard, is time-consuming and unsuitable for certain patients.
- No prior research explored optoelectronic devices for knee volume assessment.
Purpose of the Study:
- To evaluate the Perometer, an optoelectronic device, for knee volume assessment.
- To compare the Perometer's accuracy against water displacement, the established gold standard.
Main Methods:
- Bilateral knee volumes were measured in 20 uninjured subjects using both Perometer and water displacement.
- Measurements were repeated on two separate days using a one-way repeated measures design.
- A cylindrical object was measured 10 times with each device to assess precision.
Main Results:
- The Perometer overestimated cylinder volume by 2.2% and the volumeter by 3.4%.
- Both methods demonstrated high reliability for repeated knee volume measurements (r = 0.94, P<0.01).
- Wide limits of agreement (-130 to 207 ml) indicated low agreement between the two methods.
Conclusions:
- The Perometer demonstrates reliability comparable to water volumetry for knee volume assessment.
- Despite similar reliability, the Perometer and water volumetry should not be used interchangeably due to significant agreement differences.