Ultrasound of segment distraction and callus formation in reconstruction of the mandible. Value of surgical ultrasound of callus distraction of vascularized ilial crest transplants and mandibular segments in a previously irradiated area

Abstract

B-scan ultrasonography (US) was applied in patients subjected to callus distraction for bone formation at the interface of mandibular segments and vascularised bone grafts. This study consisted of 7 patients requiring further surgical augmentation to allow for prosthetic treatment. All patients had been preoperatively irradiated percutaneously in the region of the primary oral squamous cell carcinoma up to an isodose of 60-75.5 Gy. Ablative surgery was then performed, including discontinuity resection of the mandible. Vascularised iliac crest grafts had been chosen due to poor healing conditions in the irradiated recipient site. For callus distraction, a distraction device was inserted in both the mandibular segment and the bone graft. Subsequently, osteotomy was performed, and distracting forces were applied to the segments. For US, a small-part applicator was used (7.5 MHz). US gives a true estimation of the distraction length, actually achieved at the time of investigation. The applicator can be easily adjusted to the area of interest. Application is safe and easy, the results are reliable, and the procedure can be carried out without affecting the hygiene of the wound after surgical intervention. In addition, US enables the supervising surgeon to detect zones of calcification in the area of callus distraction at an earlier point than can be detected by standard x-ray documentation, thus facilitating control of the therapy. US is highly recommended for routine application in callus distraction of the mandible. X-ray documentation is a "must".