Positional change of the hyoid bone after bilateral sagittal split osteotomy with rigid and wire fixation

The purpose of this study was to compare positional changes of the hyoid bo ne and the amount of postsurgical compensation in mandibular position in pa tients who received either wire or rigid fixation after surgery. Data were analyzed from 97 patients (25 mates and 72 females) who were randomized to receive wire (43) or rigid (54) fixation after mandibular advancement surge ry as part of a multicenter clinical trial. Radiographs were digitized befo re surgery (T2), immediately after surgery (T3), and 8 weeks (T4), 6 months (T5), 1 year (T6), and 2 years (T7) after surgery. The wire group had grea ter sagittal relapse of the hyoid bone at T6 (P = .007), which persisted at T7 (P = ,02). Both groups showed upward movement of the hyoid bone after s urgery. There was no relationship between the vertical change in the the hy oid bone position and the vertical position of mandible (B point y coordina te, mandibular plane). However, there was a relationship between the horizo ntal hyoid bone position and B point during the postsurgical period (rigid, r = 0.450; wire, r = 0.517). The direct distance from the hyoid bone to ba sion increased (P < .001) in both groups at T3 and then recovered its origi nal length after 8 weeks (P < .001). The rigid group showed no significant change in distance from the hyoid to the genial tubercles, but the wire gro up showed recovery of the muscle length at T6 (P < .05) and T7 (P < .05).