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					                               Reliability of Wound Surface Area Measurements
                               Cheryl Majeske
                               PHYS THER. 1992; 72:138-141.




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Research Report

Reliability of Wound Sunface Area Measurements



 The purpose of this study was to establish intratester and intertester reliability of
four methods of measuring wound surface area from transparencyJilm tracings.
 Wound area measurements were obtained in 31 subjects with venous stasis ulcers.
After tracing each wound on transparencyJilm, wound area was calculated by
 (I) multiplying length and width measurements with a ruler, (2) placing the
 transpatencyJilm over graph paper and counting the squares, (3)using a
planimeter, and (4) using a digitizer. Intraclass correlation coeficients (ICCs)for
 intratester measurements were .99for each method. The ICC valuesfor intertester
 measurements ranged from .97 to .99. The results of this study indicate that in-
 tratester and intertester wound measurements can be taken reliably with the
graph paper, planimeter, and digitizer methods. The graph paper technique may
 be preferable in most clinical settings, because it is low in cost and easy to use.
 [Majeske C. Reliability of wound surface area measurements. Pbys Ther.
 1992;72:  138-141.

Key Words: Skin conditions; Tests and measurements, general; Ulcer; Wounds,
penetrat ing.




Physical therapists administer a variety          ruler. Fergusson and Logan3 placed                tracings of 16 wounds. Tracings were
of therapeutic procedures to patients             the transparencies over graph paper               reported to be similar, but the raw
with open wounds. The modalities                  and counted the 1-mm squares within               data for the repeated tracings were
used to facilitate wound healing in-                              f
                                                  the perimeter o the wound tracing. A              not presented and a statistical analysis
clude hydrotherapy, hyperbaric oxy-               geographer's planimeter was used by               of reliability was not performed.
gen, electrical stimulation, ultrasound,          Yucel and Basmajian4 to calculate the
and topical agents.' In order to assess           area o ulcers traced on transparency
                                                        f                                           Anthony7 investigated the intrarater
the efficacy of these therapeutic inter-          paper. Sinacore et a15 recorded ulcer             and interrater consistency in calculat-
ventions on open wounds, reliable                 area from transparency tracings using             ing pressure sore areas using three
measurements are necessary.                       a digitizer. None of these studies de-            different techniques. First, ulcers were
                                                  termined the reliability of the tech-             photographed with slide film, and a
Different techniques have been used               nique used to record wound area.                  digitizer was used to compute the
to measure wound areas from trans-                                                                  area of the ulcer from the enlarged
parency film tracings. Sterilized trans-          Kloth and F e e d d reported a tech-              slide. Second, transparency tracings
parency film is placed over the                   nique of tracing a wound perimeter                were placed over graph paper, and
wound, and the wound's perimeter is               onto plastic wrap and then transcrib-             the 1-mm squares were counted.
traced with a fine-tipped pen. Dyson              ing the tracings onto metric graph                Third, the longest and shortest diame-
and Suckling2 multiplied length and               paper to calculate wound area. One                ters of the wound were measured
width measurements taken with a                   examiner performed three repeated                 with a ruler. Measurement repeatabil-
                                                                                                    ity was assessed by the ratio of stan-
                                                                                                    dard deviation to the mean expressed
                                                                                                    as a percentage. An analysis of vari-
C Majeske, MS, PT, is Physical Therapist, St Mary's Home Health, 2307 N Parharn Rd, Ste 1, Rich-    ance (ANOVA) was used to compare
        A
mond, V 23229. She was Cardiovascular Senior Physical Therapist, Medical College of Virginia        interrater variability.
                                                          A
Hospitals, Virginia Commonwealth University, Richmond, V 23298, at the time the study was com-
pleted. Address all correspondence to Ms Majeske at 101 Woodland Cr, Quinton, V 23141 (USA).
                                                                                 A

This artic/e was submitted December 31, 1990,and was accepted Augus6 13, 1991

Physical Therapyllrolume 72, Number 2Febmary 1992
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Repeatability was greatest with the              plying length and width measure-                  ings of each wound were designated
computer method (6.0%), followed                 ments taken with a ruler, (2) placing             as a pair of tracings. One therapist
by the diameter method (11.4%) and               the transparency on graph paper and               traced 34 wounds, and the other two
the tracing method (14.0%). The com-             counting the squares, (3) using a                 therapists each traced 18 wounds.
puter method had the highest consist-            hand-held planimeter to measure                   Therapists were instructed to hold the
ency for intrarater and interrater               wound area, and (4) using a digitizer             transparency film against the subject's
measurements, whereas the tracing                to measure wound area. I expected                 leg and to avoid movement of the
method yielded the lowest repeatabil-            that all methods would be reliable                film. Care was also taken not to exert
ity for intrarater and interrater mea-           between and within raters, based on               pressure over the wounds to avoid
surements. The diameter method                   results in the literature regarding the           distortion of the wound surface. No
showed high intrarater consistency               similarity between repeated wound                 training o r practice sessions were
only.                                            tracings.                                         conducted prior to data collection.

One aspect of a diabetic foot evalua-                                                              All tracings of a given wound were
tion presented by Diamond et a18 in-                                                               done on the same day. Each therapist
volved foot ulcer measurements. The              Subjects                                          completed the two tracings on each
perimeter of a diabetic foot ulcer was                                                             patient prior to the next therapist en-
traced onto sterilized x-ray film, and a         Thirty-one patients attending the Pe-             tering the room for data collection.
sonic digitizer was used to compute              ripheral Vascular Clinic at the Medical           All tracings were coded by the clinic
the area. Intraclass correlation coeffi-         College of Virginia Hospitals (Rich-              nurse so that the therapists could not
cients (ICCs) for intrarater and inter-          mond, Va) for management of un-                   associate pairs of tracings during cal-
rater reliability of ulcer area were .99.        healed venous stasis ulcers were se-              culation of the wound areas.
                                                 lected for this study. All patients gave
In a recent study by Griffin et al,9 the         verbal consent prior to participation             Each therapist independently deter-
efficacy of healing pressure ulcers in           in the study. Each ulcer was located              mined the area of the tracings by
patients with spinal cord injury was             on the lower third o the leg and fit
                                                                       f                           each of the following four methods:
assessed. Serial measurements of                 within a 10.2-x12.7-cm (4-x 5-in)                 (1) the length and width dimensions
wound surface area were taken using              transparency film. All tracings were              (in centimeters) of the tracings were
a combined photographic slide and                made during the patients' weekly ap-              measured with a ruler* and multi-
tracing technique. Slides taken of the           pointment to the clinic. Additional               plied; (2) the tracings were placed
wound were projected at actual size              information concerning subject and                over metric graph paper, and the
onto paper, and the ulcer perimeter              ulcer characteristics was not recorded.                      f
                                                                                                   number o 1-mm squares within the
was then traced and digitized. Only                                                                tracing were counted (only full 1-mm
intratester reliability o wound surface
                         f                       Procedure                                         squares inside the perimeter were
area measurement was assessed, and                                                                 counted, and the area was converted
an ICC value o .99 was reported.
                f                                Subjects were seated with the heel of             to square centimeters); (3) the wound
                                                 the involved leg resting on a stool. All          tracings were traced with a hand-held
The literature demonstrates a variety            wounds were cleansed with soap and                Compensating Polar planimeter,+
of methods used to measure wound                 water by the clinic nurse prior to trac-          which gave a digital reading of the
area. Design and statistical differences         ings being obtained. Tracings were                area in square centimeters; and
in these studies prevent adequate                made by placing a piece of sterilized             (4) the wound areas were measured
comparison of the reliability of mea-            transparency film over the wound and              with a digitizer,* which also gave a
surements obtained with the various              tracing the wound's perimeter on the              square centimeter digital reading. All
wound measurement procedures.                    film with a fine-tipped transparency              measurements were recorded to the
                                                 marker. A separate transparency was               nearest 0.1 cm2.
The purposes of this study were to               used for each wound. Both the film
determine intratester and intertester            and the marker were of the type used              Data Analysis
reliability o four methods of measur-
             f                                   to make overhead transparencies.
ing wound area from transparency                                                                   Reliability was assessed using the
film tracings and to compare the reli-                                  f
                                                 To assess reliability o measurements,             ICC equation (1,l). The type of ICC
ability estimates. The methods were              three physical therapists made two                selected was based on a one-way
(1) estimating wound area by multi-                        f
                                                 tracings o each wound. The two trac-              ANOVA, as described by Shrout and
                                                                                                   Fleiss.'o A minimally acceptable ICC of
                                                                                                   .70 was arbitrarily chosen. The data of
'Alirned Inc, 297 High St, Dedham, MA 02026.
                                                                                                   therapist 1 (n=34) were analyzed by
                                                                                                   ANOVA to determine whether there
'Model KE62-005, Keuffel and Esser Co, Ford Rd, PO Box 800, Rockaway, NJ 07866
                                              ,                                                    was a significant difference among the
*~urnonics
         Corp, 101 Commerce Dr, Montgomel                                                          mean wound areas for each of the
                                                                                                   four methods.

58/ 139                                                                          Physical TherapyNolume 72, Number 2February 1992
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-           .
Table 1 lntratester Reliability of
Wound Area Measurements


Therapist        Method              ICC
                                              Table 2. lntertester Reliability of
                                              Wound Area Measurements for Three
                                              Therapists (n =18)


                                              Method                                   ICC
                                                                                                non and Pfallerll that counting the
                                                                                                1-mm squares can be tedious. With
                                                                                                the metric graph paper, 1-cm blocks
                                                                                                centrally located within the wound
                                                                                                tracing could be counted quickly.
                                                                                                Counting the 1-mm blocks at the
                                                                                                periphery of the tracing was time
                                                                                                consuming. The area of a 70-cm2
1 (n=34)         Ruler
                                              Ruler
                                                                                                ulcer was calculated in 10 minutes.
                 Graph paper
                                                                                                The areas of the smaller ulcers
                 Planimeter                   Graph paper
                                                                                                could be calculated within 1 to
                 Digitizer                    Planimeter
                                                                                                2 minutes.
2 (n=18)         Ruler                        Digitizer
                 Graph paper                                                                    The hand-held planimeter can be
                 Planimeter                                                                     used to calculate wound areas quickly
                                              The use of a ruler for measuring                  and requires minimal training to use.
                 Digitizer
                                              wound area in the clinical setting is             The planimeter is portable, and
3 (n=18)         Ruler
                                              easy, quick, and inexpensive. As                  wound areas can be determined im-
                 Graph paper                  higher wound areas were consistently              mediately in any setting. Many clinics
                 Planimeter                   obtained with the rule, the accuracy              or home health agencies, however,
                 Digitizer                    of this method is questionable. The               may not have this equipment. Pur-
                                              overestimation of the real wound area             chasing a planimeter ($300-$700)
                                              may be attributed to calculating area             may be cost effective, because of the
                                              by fitting a rectangular model (multi-            staff time saved in calculations. The
                                              ply widthxlength) to an irregular                 digitizer also gives a rapid calculation
The results showed that intratester           shape.                                            of wound areas and is similar in price
reliability for each therapist using all                                                        to a planimeter, but requires a per-
four me1:hods of calculating wound            The graph paper technique can be                  sonal computer.
area was high (Tab. 1); all correlation       easily incorporated into clinical
coefficients were .99. Intertester reli-      practice, because it is easy to use               Although intertester variability in de-
ability was also high (ICC = .97-.99) for     and low in cost. The clinical applica-            termining wound area with the graph
each method of determining wound              tion of the graph paper method to                 paper, planimeter, and digitizer tech-
area (Tab. 2).                                assess wound size in response to                  niques was low, research has not
                                              treatment intervention has been                   demonstrated that these methods may
The overall range in ulcer area mea-          documented.6 I agree with Bohan-                  be interchanged when performing
surements for all three therapists was
from 0.1 to 112.8 cm2 (Tab. 3). For
each therapist, the mean wound areas
calculated for the graph paper,
                                              Table 3 lntertester Measurements of Wound Area (n = I @
                                                     .
planimeter, and digitizer methods
were smaller than the mean area ob-
tained with the ruler. The means for                                                           Wound Area (crn2)
the ruler ranged from 7.9 to 10.2 cm2         Therapist              Method                    3              SD              Range
as compared with an overall range of
6.1 to 7.2 cm2 for the other three
                                                                     Ruler
methods.
                                                                     Graph paper
                                                                     Planimeter
                                                                     Digitizer
This investigation demonstrated the                                  Ruler
good reliability of each tested method                               Graph paper
of measuring wound area from trans-                                  Planimeter
parency tracings. The intratester and                                Digitizer
intertester reliability values of .99 us-
                                                                     Ruler
ing the digitizer to calculate wound
area agree with the results of Dia-                                  Graph paper
mond et al%nd Griffin et al.9                                        Planimeter
                                                                     Digitizer



Physical Therapy/Volume 72, Number 2pebruary 1992                                                                              140/59
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serial wound measurements for as-           be necessary. A variety of methods of              References
sessing wound healing. Consistent use       assessing depth of tissue involvement
of the same examiner and technique          have been described.' Additional re-              1 Kloth LC, McCulloch JM, Feedar JA. Wound
                                                                                              Healing: Alternatives in Management. Philadel-
should be emphasized.                       search on the reliability of depth mea-                      A
                                                                                              phia, Pa: F Davis Co; 1990.
                                            surements is indicated.                           2 Dyson M, Suckling J. Stimulation of tissue re-
Error in approximating the true                                                               pair by ultrasound: a survey of the mechanisms
                                                                                              involved. Physiotherapv. 1978;64:105108.
wound surface area has been sug-            Conclusions
                                                                                              3 Fergusson AG, Logan JC. Leg ulcers: assess-
gested to arise from several sources.                                                         ment of response to certain topical medica-
Anthony7 hypothesized that variability      The documentation of wound area is                tions. Br Med J. 1961;1:871-874.
in determining sore area was due to         one aspect of assessing wound heal-               4 Yucel VE, Basmajian JV. Dccubitus ulcers:
individual differences in assessing the     ing. This study has shown that intra-             healing effect of an enzymatic spray. Arch Pkys
                                                                                              Med Rehabil. 1974;55:517-519.
wound's border. Placing a transpar-         tester and intertester reliability for            5 Sinacorc DR, Mueller MJ, Diamond JE, et
ency over a wound may alter the ul-         calculating wound area with the ruler,            al. Diabetic plantar ulcers treated by total
cer size or undermine the wound             graph paper, planimeter, and digitizer            contact casting: a clinical report. Phys Ther.
                                                                                              1978;67:1543-1549.
edges.9 Bohannon and Pfallern also          methods is high. I recommend the
                                                                                              6 Kloth LC, Feedar JA. Acceleration of wound
suggest that error is introduced from       graph paper technique to clinicians               healing with high voltage, monophasic, pulsed
the tracing itself. The counting, weigh-    who do not have access to a planime-              current. Phys Ther 1988;68:503-508.
ing, and planimetry methods used by         ter or digitizer. The graph paper tech-           7 Anthony D. Measuring pressure sores. NUTS-
Bohannon and Pfaller were more ac-          nique gives therapists a low-cost and             ing Times. 1985;81:57-61.
                                                                                              8 Diamond JE, Mueller MJ, Delitlo A, Sinacore
curate with known areas than with           simple tool to record wound size.                 DR. Reliability of a diabetic foot evaluation.
ulcer areas.                                                                                  Phys Ther. 1989;69:797-802.
                                            Acknowledgments                                   9 Griffin JW, Tooms RE, Mendius RA, et al.
Clinicians must also consider that the                                                        Efficacy of high voltage pulsed current for
                                            I thank Dr Robert L Lamb for his de-              healing of pressure ulcers in patients with spi-
four measurement techniques pre-                                                              nal cord injury. Phys Ther 1991;71:433442.
sented are limited in that only the         sign and statistical suggestions. I also          10 Shrout PE, Fleiss JL. Intraclass correlations:
wound boundary is measured. This            thank Dianne Valle and Archana Deo                uses in assessing rater reliability. Psycho1 Bull.
                                            for their editorial comments.                     1979;86:420428.
may be sufficient with shallow lesions.
                                                                                              11 Bohannon RW, Pfaller BA. Documentation
Evaluating wound depth in deep                                                                of wound surface area from tracings of wound
tracking wounds, however, may also                                                            perimeters: clinical report of three techniques.
                                                                                              Phys Ther. 1983;63:1622-1624,




                                                                           Physical TherapyNolume 72, Number 2/February 1992
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                              Reliability of Wound Surface Area Measurements
                              Cheryl Majeske
                              PHYS THER. 1992; 72:138-141.




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