Correction of humpback and DISI deformities by vascularized bone grafting in patients with scaphoid nonunion

Introduction: Although vascularized bone grafting (VBG) using 1, 2 intercompartmental supraretinacular artery (1, 2 ICSRA) is effective for scaphoid nonunion, dorsal intercalated segment instability (DISI) deformity persists even after correction of humpback deformity (HD). The purpose of this retrospective study was to evaluate the correction of HD and DISI deformity after 1, 2 ICSRA VBG for scaphoid nonunion. Methods: We treated 18 patients (mean age: 25.8, 16 males and 2 females) with scaphoid nonunion using a 1, 2-ICSRA VBG between January 2010 and December 2018. The average time from injury to surgery was 20.0 (3–120) months. The nonunions were located at the waist in all patients. The correction of HD and DISI deformity was investigated on the preoperative images and images at the last examination. Results: In all patients, the correction of HD was positively correlated with that of DISI deformity. Moreover, we focused on the time from injury to surgery and evaluated changes in HD and DISI deformity according to the time to surgery. As a result, changes in HD and DISI deformity were positively correlated in patients with a shorter time to surgery but were not correlated when the time to surgery exceeded 5 months. Conclusions: These results suggest that DISI deformity can be corrected by correcting HD when the time from injury to surgery is short, but that correction is difficult if the time to surgery is prolonged.