1. Perometer (400T) measurement of lower limb volume: An investigation of criterion validity Cathy Bulley, Fiona Coutts, Andrew Grainger Queen Margaret University, Edinburgh, UK

2. Background Various musculoskeletal conditions  limb volume Limb volume – outcome measures  Fluid displacement  Geometric calculations from limb circumferences using tape measure  Perometer – optoelectronic imaging device; limb shape and volume (Pero-System GmbH)

3. Current Methods Fluid displacement: limb submerged in water, measurement of fluid displaced  inconvenient  unhygienic  poor reliability  no information on shape Geometric calculations from limb circumferences using tape measure  frequently used clinically  non-standard protocols  reliability issues

4. Circumferential Measurement Limb circumference at specified points on limb – quick, simple Lack of agreement on measurement points – specific anatomical landmarks or regular intervals e.g. 3 or 4 cm (Karges et al, 2003) Geometric formulae to estimate volume of different segments  summed Different formulae used (e.g. disc model, truncated cone model) Reliability issues: e.g. tape measure tension (Brorson, 2000)

5. Perometer (Pero-System GmbH)  optoelectronic imaging device  limb shape and volume  quick, easy Base plate Frame Track

6. Perometer estimation of limb volume Positioned every 2.54 mm Positioned every 1.27 mm Diameter measurements every 4.7 mm Summed volume of elliptical discs

7. Perometer – gold standard? Face validity Lack of standardised protocol and research Criterion Validity: This study compared lower limb volume measured using :  Geometric calculation from limb circumferences (Tape measure Disc model method, Man et al, 2004)  Perometer (400T: upright model) Purpose

8. Standardised Protocol Development of a standardised protocol  Limb position on the base plate, and degree of rotation  Lower limb landmarks – standardised proportion of the limb for volume measurement Greater trochanter 65% Femur Lateral epicondyle Lateral Malleolus

9. Validity Study Ethical approval: Physiotherapy Ethics Sub- Committee, QMU. 30 healthy volunteers:  22 F, 8M  mean age: 26  mean height: 67.2 cm  mean weight 171.0 kg.  Exclusion criteria: relevant past medical history

10. Protocol 1 Participants requested to avoid vigorous exercise / alcohol consumption 24 hr before testing and avoid food / drink intake 1 hr before testing 15 minute rest period with limb elevated to 90° Standardised limb reference marks

11. Protocol 2 Standardised limb reference marks Standardised positioning of limb in Perometer frame – use of spirit level Three Perometer measurements Tape measurements at 3 cm intervals Assessor blinded to limb volume

12. Limb volume estimation Perometer: Volumes in ml calculated between two reference marks in perometer computer software Tape measurements: Disc model method (Man et al, 2004) in ml (1ml = 1 cm 3 ) Σ (C²/4π) x h C = circumference of disc h = height of disc

13. Statistical Analysis Shapiro-Wilk: Normality of distribution Parametric inferential statistics:  ICC (3,1)  Limits of agreement (Bland & Altman, 1986) between two limb volume estimates

14. Results Perometer limb volume (x of 3) = 8560 ml Normal distribution p=0.268 Circumferential limb volume = 8717 ml Normal distribution p=0.602 Difference 157 ml ICC (3,1): good association (0.952, p<0.001) Poor agreement 15.67% variation between estimates: 95% of Perometer estimates will be: between 519 ml (6.01%) more and 834 ml (-9.66%) less than circumferential estimates

16. Conclusions Poor agreement – measurement methods are not interchangeable  Perometer – greater face validity  Circumferential – more clinically feasible Results do not indicate accuracy of either method 21 / 30 data sets – overestimation by circumferential method More work is needed to determine accuracy

17. Acknowledgements MSc pre registration Physiotherapy students: Nicola Dinsmore Georgina Enderson MaryAnne Geraghty

18. Sponsors: School of Health Sciences, Queen Margaret University, Edinburgh Centre for Integrated Healthcare Research, Edinburgh THANK YOU

19. References Bland J, Altman D (1986) Statistical methods for assessing agreement between two methods of clinical measurement. The Lancet 8: 307-310 Brorson H (2000) Liposuction gives complete reduction of chronic large arm lymphoedema after breast cancer. Acta Oncologica 39: 407-420 Karges J, Mark B, Stikeleather S et al (2003) Concurrent validity of upper-extremity volume estimates. Physical Therapy 83: 134-145 Man I, Markland K, Morrissey M (2004) The validity and reliability of the Perometer in evaluating human knee volume. Clinical Physiology and Functional Imaging 24: 352-358