Natural History and Consequences of Nonunion in Mandibular and Maxillary Free Flaps

Abstract

Objective To describe the natural history of bone segment union in head and neck free flap procedures and detail the association of poor segment union with postoperative complications. Study Design Case series with chart review. Setting Single tertiary care referral center. Subjects and Method Patients with mandibular or maxillary defects reconstructed with osseous or osteocutaneous free flaps were analyzed (n = 104). Postoperative computed tomography or positron emission tomography/computed tomography scans were reviewed for signs of osseointegration and nonunion. Postoperative wound complications were correlated with imaging findings. Result Thirty-seven percent of appositions had partial union on nonunion. Appositions between osteotomized free flap segments form complete unions at a higher rate than appositions with native bone (65% vs 53%, P = .0006). If an apposition shows a gap of ≥1 mm, the chances of failing to form a complete union are greatly increated (79% vs 8%, P = .0009). Radiographic nonunion was associated with an increased likelihood of postoperative wound complications (40% vs 19%, P = .025) and in most cases was present before development of complications. Conclusion Radiographic evidence of partial union or nonunion of free flap osseous segments greatly exceeds reported rates of clinically evident nonunion. Unions likely form between free flap appositions before unions to the native bone. If initial bone segments are >1-mm apart, the chance of progression to complete union is low. Incomplete osseointegration appears to be a marker for development of wound complications.

Influence of Radiotherapy on Ossification of Vascularized Osseous Reconstruction of the Jaw: A Radiological Retrospective Cohort Study Based on Panoramic Radiographs

“…Nevertheless, contact between two graft segments showed significantly faster complete ossification than the contact points between bone graft and original bone. Swendseid et al showed a similar effect, including less dependency on distance between graft segments for complete ossification [ 41 ]. In this context, the data from our multivariate analysis emphasized that radiotherapy as well as the type of bone contact (graft/native vs. graft/graft) showed significantly stronger impacts on ossification and the initial quality of bone contact.…”

Rates of bone reabsorption and union in mandibular reconstruction using the osteocutaneous radial forearm free flap

“…Prior investigations on the integration of native to implanted bone union have been conducted. The mandible warrants special consideration due a unique set of torsional and tension forces acted upon this segment of bone 14,15 . Alterations in masticatory muscles due to resection can cause unbalanced jaw movement, complicating the understanding of forces further 15 .…”

“…While prior studies included patients who underwent OCRFFF, they represent a minority of cases. The literature approximates that the rate of nonunion in FFF surgery ranges from 5% to 20% 13–15,19,22,23 . Few investigations have exclusively investigated the degree of bone union in the OCRFFF, but those that have suggest that the rate of nonunion is approximately 2%–5% 2,24–26 .…”

“…Variables found correlating with progression of bone union included women and never smokers (OR 7.5, 95% CI 1.2–47.1 and OR 3.3, 95% CI 0.53–20.9, respectively). In addition, Swendseid et al found a correlation between nonunion with wound dehiscence, plate infection, hardware extrusion, and osteonecrosis 14 . Arganbright et al report that malunion/nonunion at the recipient site for OCRFFF occurred in 4/167 cases reviewed in cohort spanning 10 years at the University of Kansas Medical Center 2 .…”

“…This study was designed to examine the change in bone volume and rates of bone union of OCRFFF over time as surrogates of vascularization and bone health. To best accomplish this, the reconstruction site was limited to the mandible as this area is exposed to unique and high‐tension forces, therefore providing the most rigorous of environments to evaluate outcomes 14,15 . This study also seeks to identify factors that impact bone resorption and bone union and examine long‐term complication data.…”