Outcomes of Osseous Microvascular Midface Reconstruction: Does Union Matter?

To assess rates of bony union and their correlation with postoperative complications following osseous orbitomaxillary microvascular reconstruction.

A retrospective review was performed of patients who underwent orbitozygomaticomaxillary reconstruction with composite osseous free flaps at an academic medical center from 2011 to 2024. Demographics, intraoperative variables, and postoperative outcomes were collected. Univariable and multivariable regression analyses were conducted to evaluate factors associated with bony union.

Fifty-nine patients were identified, with a mean follow-up of 3.53 years. Most subjects underwent maxillary reconstruction following oncologic resection (72.9%). The predominant flap used was the fibula free flap (78.0%), followed by the osteocutaneous radial forearm flap (16.9%). Complication rates included hardware extrusion (25.4%), fistula formation (40.7%), and bone exposure (15.3%). The rate of complete bony union was 50.0%, with partial and nonunion rates of 13.3% and 37.7%, respectively. Nonunion was more likely among patients with fistula formation (OR 4.29, p = 0.038) and those who underwent subsequent free flap (OR 8.46, p = 0.008). Multivariable regression found nonunion was associated with increasing number of sites of possible osteosynthesis (OR 36.8, p = 0.007), use of Virtual Surgical Planning (VSP) (OR 100.5, p = 0.045), and postoperative radiation therapy (OR 13.8, p = 0.032). Age, ASA class, surgeon, flap type, use of locking versus non-locking plates, ischemia time, and time from surgery to CT were not associated with nonunion.

Nonunion occurred in approximately one third of cases and was associated with increasing sites of possible osteosynthesis, use of VSP, adjuvant radiation, fistula formation, and subsequent free flap.