Four-corner arthrodesis in SNAC wrist: biomechanical and functional comparison of two fixation techniques

Scaphoid nonunion advanced collapse (SNAC) is a debilitating condition that significantly impacts wrist function, pain levels, and return-to-work outcomes. Surgical fixation method may influence long-term functional results. This study aimed to compare the complications and functional outcomes of four-corner arthrodesis using either a CarpalFix screw system or a dorsal locked circular plate.

Patients diagnosed with SNAC wrist who underwent four-corner arthrodesis between 2016 and 2022. A total of 47 patients were included: 25 treated with dorsal circular plate fixation and 22 with CarpalFix screw fixation. Pre- and postoperative assessments included the Visual Analog Scale (VAS) for pain, Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) scores, wrist range of motion (ROM), and grip strength using a JAMAR dynamometer. Time to return to work and complications such as nonunion were also evaluated.

The CarpalFix group demonstrated significantly greater postoperative wrist flexion and total flexion-extension ROM compared to the dorsal plate group. Time to return to work was also shorter in the CarpalFix group. No significant difference in grip strength was found between groups. Three cases of nonunion occurred, all in smokers; however, this was not statistically significant.

CarpalFix screw fixation provides comparable outcomes to dorsal circular plate fixation in the treatment of SNAC, with advantages in motion preservation and earlier return to work. Its low-profile design and strong compression capability make it a favorable option, particularly in younger patients.