Comparison of PACS and hard-copy 51-inch radiographs for measuring leg length and deformity.
BACKGROUND
The picture archiving and communication system (PACS) eventually will replace the use of standard hard-copy radiographs. It is unknown whether measurements of limb length discrepancy (LLD) and deformity on PACS compare in accuracy and reproducibility with those from hard-copy radiographs.


OBJECTIVE
We compared the reproducibility and reliability of LLD and deformity measurements for each of these two media.


METHODS
We retrospectively reviewed 51-inch standing lower extremity images obtained for LLD or deformity analysis from 40 patients to compare the measurements and their reliability on hard-copy film with those performed on soft-copy PACS. Two observers independently performed measurements twice using each system at 1-week intervals to minimize interobserver or intraobserver bias. Intraclass correlation coefficients (ICCs) were determined to test intraobserver and interrater reliability of Rater 1 and Rater 2.


RESULTS
Interrater reliability of measurements made on hard copy ranged from 0.69 to 0.99 and PACS-derived measurements ranged from 0.66 to 0.98. Intraobserver reliability for Rater 1 for measurements made on hard copy ranged from 0.853 to 0.999 and PACS-derived measurements ranged from 0.80 to 0.996. Intraobserver reliability for Rater 2 for measurements made on hard copy ranged from 0.931 to 0.999 and PACS-derived measurements ranged from 0.962 to 0.999.


CONCLUSIONS
Each system yielded comparable reliability for measurements, therefore, transition to PACS to perform measurements in patients with LLD or deformity can be made with confidence.


METHODS
Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.
Khakharia
Saurabh
S
Department of Orthopedic Surgery, Limb Lengthening and Deformity Service, Hospital for Special Surgery, Affiliated with Weill Medical College of Cornell University, 535 East 70th Street, New York, NY 10021, USA. khakharia@gmail.com
Bigman
Daniel
D
Fragomen
Austin T
AT
Pavlov
Helene
H
Rozbruch
S Robert
SR
D006801:Humans; D007870:Leg Length Inequality / Q000000981:diagnostic imaging*; D038061:Lower Extremity Deformities, Congenital / Q000000981:diagnostic imaging*; D009519:New York City; D015588:Observer Variation; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D011873:Radiology Information Systems; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014962:X-Ray Film