A novel technique for digital assessment of hand volume

• Published in: Journal of hand therapy Vol. 38; no. 2; pp. 178 - 188
• Main Authors: Katouzian, Nastaran, Parent, Claire A., Eagleson, Roy, Symonette, Caitlin
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2025; Elsevier Limited
• Subjects: Adult; Algorithms; Cameras; Computer vision; Correlation coefficient; Correlation coefficients; Cross-Sectional Studies; Digital; Digital computers; Digital imaging; Feasibility studies; Female; Figure-of-eight; Hand - anatomy & histology; Hand - diagnostic imaging; Hand swelling; Hand volume assessment; Humans; Male; Measurement techniques; Methods; Middle Aged; Patients; Pilot Projects; Range of motion; Regression analysis; Swelling; Volume measurement; Volumetric analysis; Water displacement; Webcams; Young Adult; Computer vision; Digital; Figure-of-eight; Water displacement; Hand swelling; Hand volume assessment
• ISSN: 0894-1130; 1545-004X; 1545-004X
• DOI: 10.1016/j.jht.2025.03.001

Swelling is an anticipated nonspecific response following hand trauma, arthritis, infection, or surgery, which can decrease range of motion and increase pain. Approaches to quantify swelling, typically performed through hand volume measurement, are lacking in routine clinical assessments. A hand volumetry technique that is quick, inexpensive, noninvasive, and reliable is still in demand. With advances in computer imaging, new technologies are increasingly gaining attention to enable the digital assessment of hand volume as a surrogate marker of swelling. This study aims to develop a webcam-based method using computer vision technology for digital hand volume assessment and compare its results with those from conventional water displacement and figure-of-eight techniques to evaluate its feasibility in healthy hands. Cross-sectional observational pilot study. A novel algorithm was developed to process hand images captured through a webcam. Digital hand volume was computed using both palmar and lateral view area calculations. Thirty healthy participants were recruited. The volumes of their hands were measured using three methods: the proposed digital method (VD), water displacement (VW), and figure-of-eight taping (CFOE). Digital volumes were compared to conventional approaches using Pearson correlation coefficients and Bland-Altman analysis. A strong correlation was observed between VD and CFOE (r=0.89, p<0.00001). Similarly, VD demonstrated a significant correlation with VW (r=0.96, p<0.00001). However, a systematic overestimation by VD was identified and subsequently adjusted using a calibration curve derived from regression analysis, resulting in the calibrated hand volume (VD*). Bland-Altman analysis between VD* and VW indicated Limits of Agreement (LOA) of ±33.6 mL, with percentage limits ranging from −9.5% to 9.3%. This study demonstrates a novel approach to digital hand volume assessment. Our findings suggest that when LOA of ±9.5% is considered clinically acceptable, the digital method can be used interchangeably with water displacement volumetry in nonpathological hands. •Novel computer vision method in DIGITS measures hand volume from webcam frames.•OpenCV algorithm computes hand volume from palmar and lateral hand areas.•Digital volume strongly correlates with water displacement and tape measurements.•Digital hand volume method enables remote hand swelling assessment effectively.