Changes in weight and body composition after orthognathic surgery and jaw fractures: a comparison of miniplates and intermaxillary fixation.

[OBJECTIVES] To compare the changes in postoperative weight and body composition following orthognathic surgery or jaw fractures treated by intermaxillary fixation (IMF) or miniplate osteosynthesis.

[DESIGN] A 4-month non-randomised prospective pilot study. Body composition was assessed using the 4 site skinfold thickness technique. The fixation method used in each case was dependent on clinical criteria alone.

[SETTING] Oral and maxillofacial surgery units at St James's University Hospital and the General Infirmary at Leeds.

[SUBJECTS] All patients were eligible for inclusion in the study if they had sustained a jaw fracture or had undergone orthognathic surgery. Patients were excluded if they had sustained polytrauma, if their sole orthognathic surgery procedure was a genioplasty and if the author was not directly involved in their management. The final study group consisted of 22 patients, 18 following surgical correction of jaw fractures and 4 following elective orthognathic surgery. Thirteen patients were managed with intermaxillary fixation and 9 patients were treated with miniplate osteosynthesis.

[MAIN OUTCOME MEASURES] Weight, lean body mass, total body water, fat and water free lean body mass, 1 week and 6 weeks postoperatively.

[RESULTS] There was no significant difference in weight loss or body composition changes between the plated and non plated groups at 1 week postoperatively. However, by 6 weeks postoperatively the IMF group had lost significantly more weight (4.5 kg) than the plated group (1.1 kg). In the plated group this weight loss resulted entirely from a loss of lean body mass (77% water), whereas in the other group it resulted from a fat loss of 1.2 kg plus a lean body mass loss of 3.3 kg (73% water). Estimated protein losses were 0.9 kg for the IMF group and 0.3 kg for the plated group.

[CONCLUSIONS] Intermaxillary fixation compromises nutritional status in the early postoperative period leading to loss of water, fat and protein. The results of this pilot study suggest that further investigation of postoperative weight and body composition changes after oral and maxillofacial operations is indicated.