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The Accuracy of an Automasking Algorithm in Plantar Pressure Measurements


Masking algorithms provide a way to analyze plantar pressure parameters based on distinct anatomical regions of the foot. No study has addressed their accuracy. The purpose of this study was to determine the accuracy of the Novel® ten-region standard masking algorithm in both dynamic and static measurements in normal feet. Static and dynamic plantar pressure measurements were collected from ten normal subjects (20 ft) with and without 10-mm radiopaque markers placed under the first through fifth metatarsal heads, fifth metatarsal base, and first proximal phalanx. The automask was then applied to subdivide the foot into distinct anatomical areas. Weight-bearing AP radiographs were obtained with and without markers. Plantar pressures and radiographs were overlaid. The percent accuracy of each marker within its appropriate mask region was calculated. The average accuracies of the automasking algorithm regions for dynamic and static measurements, respectively, were 98.8% and 90.4% (1MH), 89.9% and 80.6% (2MH), 98.6% and 81.4% (3MH), 96.8% and 82.3% (4MH), 93.1% and 80.8% (5MH), 97.3% and 92.5% (5MB), and 91.2% and 64.2% (1PPH). Marker presence did not alter foot structure or function as determined by intermetatarsal angles (range, p = 0.361 to p = 0.649) and the center of pressure excursion index (p = 0.727), respectively. The automasking algorithm accurately identifies most foot regions in normal feet, particularly in gait. Such accuracy may be reduced in the setting of foot deformity. Understanding the accuracy of masking algorithms may help guide the interpretation of plantar pressure measurements and ultimately both conservative and operative treatment decisions.

This article appears in HSS Journal: Volume 7, Number 1.
View the full article at springerlink.com.

About the HSS Journal
HSS Journal, an academic peer-reviewed journal, is published twice a year, February and September, and features articles by internal faculty and HSS alumni that present current research and clinical work in the field of musculoskeletal medicine performed at HSS, including research articles, surgical procedures, and case reports.


Headshot of Scott J. Ellis, MD
Scott J. Ellis, MD
Associate Attending, Orthopaedic Surgery, Hospital for Special Surgery
Associate Professor of Orthopaedic Surgery, Weill Cornell Medical College

Hill Stoecklein, BS
Department of Foot and Ankle Surgery, Hospital for Special Surgery

Joseph C. Yu, BS
Department of Foot and Ankle Surgery, Hospital for Special Surgery

Grisha Syrkin, BS
Department of Foot and Ankle Surgery, Hospital for Special Surgery

Howard Hillstrom, PhD
Leon Root Motion Analysis Laboratory, Hospital for Special Surgery

Jonathan T. Deland, MD
Chief of the Foot and Ankle Service, Hospital for Special Surgery
Associate Attending Orthopaedic Surgeon, Hospital for Special Surgery
Associate Professor of Surgery (Orthopaedics), Weill Cornell Medical College

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