Use of Stress-Shielding Reconstruction Plates in Free Fibula Mandible Reconstruction May Be Associated with Increased Rates of Bone Resorption: Preliminary Report

Prior studies by Hidalgo and colleagues have reported that a fibula flap used for mandible reconstruction preserves sufficient bone mass over time to support osseointegrated implants. Their group used miniplates for mandible fixation. As other centers, including the authors' own, utilized reconstruction plates for fixation, an unresolved question has been whether stress-shielding reconstruction plates lead to increased bone resorption in the fibula with time. This is important as it may adversely affect the success of dental rehabilitation. The authors investigated this possibility in a group of patients who underwent mandible reconstruction with a fibula free flap for benign diseases, thereby obviating the confounding effects of irradiation.

A retrospective analysis of 70 fibula free flap mandible reconstructions performed over the last 10 years in a city hospital revealed 7 patients (10%) who had resections for benign odontogenic diseases. All had a 3-D cast model made, upon which the reconstruction plate was pre-bent to the desired shape preoperatively. The bone height of the reconstructed mandible was measured immediately postoperatively, at 2 months, and at 1 year postoperatively. Six of seven flaps survived; one flap failed and was salvaged with a second fibula flap. No other complications were noted. An average of 3 osteotomies (range: 2–4) of the fibula were performed in situ on the fibula under the pre-bent plate. This allowed 100% accuracy in maintaining preoperative occlusion and in accurately conforming the fibula flap to the extirpative defect. In this series, bone height was maintained at 2 months postoperative but at 12 months postoperative, there was a loss of fibular bone height averaging 20% in the anterior, body, and ramus areas. Despite this, all patients were considered eligible for implants, and 4/7 patients have had osseointegrated implants placed. All implants placed to date have been successful. The authors reported a trend toward increased resorption of the fibula over time, compared to a prior study by Hidalgo and colleagues. This may be due to use of a reconstruction plate for fixation, as opposed to miniplates, and may result from the phenomenon of stress-shielding unique to the use of a heavy reconstruction plate. However, this did not appear to affect the ability to place osseointegrated implants in the reported patients with benign diseases. It may not hold true in patients who receive irradiation. The authors are currently determining bone resorption rates in patients who receive postoperative radiation to determine prospectively the optimal fixation method to use in these patients.