Establishment of Normative Values of First Webspace Measurements in the Pediatric Population
Isaac Betaharon, BS1, Danielle A Hogarth, MD1, Casey M Codd, BA1, Catherine C May, BS2 and Joshua M Abzug, MD1, (1)University of Maryland School of Medicine, Baltimore, MD, (2)University of Maryland School of Medicine, Timonium, MD
Introduction
Congenital conditions and injuries of the hand are commonly observed in the pediatric population and often go unrecognized if functional limitations are not present. Conditions such as thumb hypoplasia and thumb contractures may be optimally treated prior to the development of functional limitations. The purpose of this study was to establish normal values of first webspace of the hand measurement in the pediatric and adolescent populations.
Methods
A total of 308 hands were measured from 179 unique participants (101 male, 78 female; 0-18 years) recruited from a population of pediatric orthopaedic patients and their siblings. Measurements were taken of each hand of each patient, unless the child presented with a history of an injury to a particular limb and/or had a known congenital hand/digit condition, history of upper extremity surgery, brachial plexus birth palsy, or neurodevelopmental disorder. The measurements included the first webspace depth in centimeters, the first webspace angle in degrees, and the distance from the tip of the thumb to the proximal interphalangeal joint of the index finger in centimeters when the thumb was adducted. Simple statistical means and Pearson’s R-squared values were determined using Microsoft Excel.
Results
Mean values of the first webspace measurements were established for ages 2 through 15 (mean age: 8.18 years; SD: 4.13 years), however, too few participants were ages 1 and 16 through 18 to establish mean values. A strong linear relationship was found between age and first webspace depth (R2 =0.96) as well as age and thumb-PIP distance (R2=0.93), indicating both measurements were dependent on age. Average values for first webspace depth ranged from 2.0cm to 6.0cm. No relationship was found between age and first webspace angle (R2= 0.03) ranging from 25 degrees abduction to 93 degrees abduction.
Conclusions
The first webspace depth and distance from the tip of the thumb to the index finger PIP joint increase proportionally with increasing age. First webspace angle was not found to be a function of age or change as a child develops. The normative values defined for the pediatric population in this study can be clinically utilized to determine abnormal thumb development, the presence of a first webspace contracture, and/or early identification of the presence of underlying congenital conditions. To our knowledge, no evidence-based normative values have previously been established throughout childhood for first webspace parameters in normal children.
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