The Outcomes of the Lag-Screw Use for Treatment of the Mandibular Symphysis, Parasymphysis and Oblique Body Fractures
Background: For most fractures of the mandible, the aim of treatment is primarily to restore function, the occlusion, and pain-free normal movements of both temporomandibular joints. One of the methods of open reduction and fixation is Lag screw. The concept of Lag Screw osteosynthesis is defined as the stable union of two bone fragments under pressure with the aid of screws which in turn are under tension. The lag screw technique was first introduced to Maxillofacial Surgery by Brons and Boering in 1970 who cautioned that at least two screws are necessary to prevent rotational movements of the fragments in mandibular body fractures.
Aims: The study is aimed to assess the post-operative results by assessing the primary stability and the need for any supplemental maxillomandibular fixation (MMF), measure the time required to complete the procedures and evaluate the incidence of post-operative complications.
Materials and Methods: This was a prospective clinical study conducted from December 2017 to December 2018. The sample included patients who attended the Department of Oral & Maxillofacial Surgery / Ghazi Al-Hariri Teaching Hospital /Medical City /Baghdad subjected to maxillofacial trauma with mandibular fractures (symphyseal, parasymphyseal region and oblique body). Patients above the age of 14 years until 50 years. A total of 10 patients fulfilled the inclusion criteria participated in this study. Those patients were treated with the use of lag screws.
Results: Study patients’ age was ranging from 14-50 years with a mean 24.2 years. Regarding gender, the proportion of males was higher than females with a male to female ratio of 4:1. Parasymphyseal and oblique body fracture were the most common sites of fracture (40% for each). Mobility was absent in 60% of them intraoperatively, while it was 80% after one month. After six months, all study patients did not show any mobility. Occlusion was corrected in 90% of them intraoperatively. No displacement observed in 90% of them intraoperatively. It had been noticed that 60% of patients did not complain from any intraoperative complications, while fracture of drill and incorrect screw position were occurred in 20% of patients. It had been noticed that the mean of duration of operation was significantly higher in operation by extraoral approach than that by intra-oral approach.
Conclusion: Lag screw technique can achieve good stability and appropriate compression. The technique needs proper case selection and careful instrumentation. Two lag screws better to be used wherever possible. Excellent rigidity achieved by the lag screw fixation. Optimal stability of treated fractures by lag screws is obtained in all cases.