Biomechanics of the hand: Use of the SIGMA glove

Assessment of surgical outcomes after reconstructive surgery of the hand is a difficult problem. Static goniometric measures of joint angles and subjective evaluation of specified tasks form the core of this appraisal. A custom built glove has been constructed at the University of Sheffield - Sheffield Instrumental Glove for Manual Assessment - (SIGMA) from carbon ink bend sensors and interfaced with a computer. From the 28 sensors placed within the glove real time measures of joint angles that are associated with different manipulative assignments can be collected, displayed and stored for evaluation. To visualise this procedure a virtual hand has been constructed from digitised images. The virtual hand moves in synchrony with the fingers that are enclosed in the SIGMA glove. The studies undertaken to calibrate, validate and assess the reliability of the new computer interfaced measuring device are reported. A metal hand with fingers that could be positioned at known angles was used for calibration. The SIGMA glove was validated on this hand against the 'gold standard' of static goniometry using the method of agreement advocated by Bland and Altman. Reliability was tested using a proforma produced from plaster of paris, and was assessed by intraclass correlation using ANOVA with repeated measures. An individual subject gripped the proforma to leave an imprint and then, wearing the SIGMA glove this device was gripped and released 20 times.