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A method for repairing zygomatic arch fractures using a hydroxyapatite cement paste (BoneSource)

Abstract:

A new method has been developed for the closed reduction of minimally displaced, noncomminuted zygomatic arch fractures that is minimally invasive and precludes the use of nonresorbable materials such as plates and wires in the repair. Twenty rats received simple, minimally displaced right-sided zygomatic arch fractures under general anesthesia. In 10 animals these fractures were treated with closed reduction through a temporal approach (Gillies method) to reapproximate the fractured segments. In the second group of 10, immediately after the closed fracture reduction, 1 ml of hydroxyapatite cement paste (BoneSource) was injected through a 14-gauge needle into and around the fracture site. This paste, which is remodeled into bone over time, hardens into a plaster-like substance within 20 minutes of mixing. The majority of the paste was placed on the medial aspect of the fracture to act as a buttress between the fractured zygoma and the temporalis muscle lying on the greater wing of the sphenoid. This served to support the fracture by 'casting' the bone and preventing it from collapsing medially. Nine of the 10 fractures treated with the hydroxyapatite paste healed completely without evidence of zygomatic displacement or malunion. One fracture had mild displacement of the fractured segment but good bone healing between the fractured sides. No adverse effects were noted in the temporalis muscle of these animals, and mastication was normal. Five of the 10 treated with closed reduction alone also had a good result. Of the remaining 5 fractures, 2 had a mild to moderate bony deformity as a result of improper alignment during fracture healing. The other 3 did not heal and, therefore, formed a fibrous nonunion at the fracture site. We concluded that closed reduction of simple zygomatic fractures can be performed if the fracture site is held in place with a stabilizing material such as a hydroxyapatite cement paste.