The effect of transverse carpal ligament lengthening on carpal tunnel volumetry: a comparison between four techniques.

Transverse carpal ligament (TCL) reconstruction after open carpal tunnel release has been advocated to restore wrist kinematics and grip strength. This study investigates the effect of TCL reconstruction in carpal tunnel volume (CTV). Thirty-eight cadaveric wrists were volarly approached and TCL was exposed to its proximal and distal edges. Carpal tunnel contents were removed and the CTV was measured considering that carpal tunnel resembled the shape of a truncated cone. TCL was then dissected and subsequently reconstructed by using 4 different surgical lengthening techniques. Three of these techniques were retrieved from the literature. The fourth was proposed and performed by the authors. Postreconstruction calculation of CTV was done with the same method. In 6 cadavers, a magnetic resonance imaging-based measurement of CTV was performed to assess the validity and reliability of simulation method. The average increase of CTV ranged from 31% to 44% (P < 0.001 for all techniques). However, no statistical significant difference was found between the 4 techniques (P = 0.097). Magnetic resonance imaging volumetric values were equal to simulation measured values before and after reconstruction of TCL (P = 0.224 and P = 0.674, respectively). Lengthening of TCL substantially increases the carpal tunnel capacity regardless the applied surgical technique. The simulation model method seems to be an accurate, precise, and cost-effective approach for the evaluation of CTV.