Mechanisms of orbital blowout fracture: a critical review of the literature.

OBJECTIVE: The aim of the present study is to critically review relevant literature regarding the mechanism of blowout fractures of the orbit and provide an answer to the question: Can one theory adequately explain the mechanism of orbital blowout fractures in the light of present day knowledge? MATERIALS AND METHODS: A computerised literature search using MEDLINE was conducted for published articles on orbital blowout fractures. Mesh phrases used in the search were: orbital blowout fractures AND mechanisms; orbital blowout fractures AND theory; orbital wall injury AND mechanisms. Only relevant articles were selected for the review. RESULTS: The physical mechanism of orbital blowout fracture has been a subject of debate for years by maxillofacial surgeons, ophthalmologists, plastic surgeons, otolaryngologists and orbitologists. However, only 3 mechanisms of injury have been proposed namely: "hydraulic" theory, "globe-to-wall" theory and "bone conduction" theory. Most of the theories of orbital blowout fractures have been confirmed through brilliant experiments and hypothetical explanation/analysis of clinical and radiologic findings, and each one appears to fit according to the different type of trauma received. CONCLUSIONS: Based on contemporary evidence, one theory may not adequately explain all types of fractures completely or be responsible exclusively in a given case for the pattern of fracture observed. Blowout fractures of the orbit could therefore be due to a combination of 2 or more mechanisms.

Zygomatic arch reconstruction with autogenous rib bone graft in a post irradiated patient -- a case report.

Reconstruction of zygomatic arch using an autogenous free non-vascularised bone graft is presented. The zygomatic arch was resected along with the masseter and part of temporalis muscle following a histologically diagnosed case of chondrosarcoma. She received radiotherapy 3 weeks post-operatively to the site. The resultant facial asymmetry was unacceptable to the patient. She was therefore rescheduled for reconstruction of the zygomatic arch despite the anticipated attendant risk of avascular bed for the graft. Bone grafting was done 44 months post irradiation and the patient had been followed up for 38 months without evidence of rejection. We evaluated other sites of possible bone of similar contour and thickness to the zygomatic arch; we found the rib most suitable, despite the poor quality of rib as graft material, because it is a dense, thick bicortical bone with low proportion of cancellous bone, although it is the second most favoured donor site for free bone graft. The advantages of the rib as a graft are that it presents a contour that could be shaped to fit many defects, it is available in sufficient length up to 12-18 cm to fit large defects, the donor site regenerates when the periosteum is preserved.