Astrid Wilk

Clinical experience with osteosynthesis of subcondylar fractures of the mandible using TCP® plates

AIM To evaluate the clinical and radiological results obtained with a new kind of osteosynthesis device (Modus TCP) plates, Medartis, Basel, Switzerland), especially designed for low subcondylar fracture (LSCF) and high subcondylar fracture (HSCF) of the mandible in association with the high submandibular approach (HSMA). METHOD A prospective clinical and radiological study was carried out over a 41-month period. All adult patients suffering from a displaced LSCF or HSCF who consented to the surgical treatment were included in the study. All fractures were operated on using an HSMA and were stabilised using a 4- or 9-hole TCP((R)) plate. No intermaxillary fixation was used and a soft diet was started on the 1st postoperative day. Clinical examinations and control X-rays were carried out on the 10th postoperative day, in the 1st, the 3rd and, at least, in the 6th postoperative months. MATERIAL Sixty-four patients (12 females, 52 males - mean age: 28.3) with a total of 75 fractures (54 LSCF, 21 HSCF) were included in the study. Mean postoperative follow-up was 14 months. RESULTS In the 6th postoperative month, all fractures were consolidated in 79% of the cases in an anatomical position. A secondary displacement of the fracture occurred in 6.6% of the cases. Plate fracture was not observed. Dental occlusion remained unchanged in 94% of the patients. The mandibular movements (mouth opening, protrusion, lateral movements on the unfractured and fractured side) had normal mean values (49.5, 10.4, 12.8, 12.1mm, respectively). These movements were symmetrical in 95% of the patients. No patient complained about articular pain or noise. No facial nerve palsy was noticed, not even a transiently one. All patients but one found the scars acceptable. CONCLUSION TCP plates, in association with HSMA, were found to be an efficient osteosynthesis device for stabilising subcondylar fractures.

Position paper from the IBRA Symposium on Surgery of the Head – The 2nd International Symposium for Condylar Fracture Osteosynthesis, Marseille, France 2012

BACKGROUND This is a position paper from the 2nd International Bone Research Association (IBRA) Symposium for Condylar Fracture Osteosynthesis 2012 was held at Marseille, succeeding the first congress in Strasbourg, France, in 2007. The goal of this IBRA symposium and this paper was to evaluate current trends and potential changes of treatment strategies for mandibular condylar fractures, which remain controversial over the past decades. METHODS Using a cross-sectional study design, we enrolled the consensus based on the panel of experts and participants in the IBRA Symposium 2012. The outcomes of interest were the panel and electronic votes on management of condylar base, neck and head fractures, and panel votes on endoscopic and paediatric condylar fractures. Appropriate descriptive and univariate statistics were used. RESULTS The consensus derived from 14 experts and 41 participant surgeons, using 12 case scenarios and 27 statements. The experts and participants had similar decision on the treatment of condylar base, neck and head fractures, as well as similar opinion on complications of condylar fracture osteosynthesis. They had a parallel agreement on using open reduction with internal fixation (ORIF) as treatment of choice for condylar base and neck fractures in adults. Endoscopic approaches should be considered for selected cases, such as condylar base fractures with lateral displacement. There was also a growing tendency to perform ORIF in condylar head fractures. The experts also agreed to treat children (>12 years old) in the same way as adults and to consider open reduction in severely displaced and dislocated fractures even in younger children. Nevertheless, non-surgical treatment should be the first choice for children <6 years of age. The decision to perform surgery in children was based on factors influencing facial growth, appropriate age for ORIF, and disagreement to use resorbable materials in children. CONCLUSIONS The experts and participating surgeons had comparable opinion on management of condylar fractures and complications of ORIF. Compared to the first Condylar Fracture Symposium 2007 in Strasbourg, ORIF may now be considered as the gold standard for both condylar base and neck fractures with displacement and dislocation. Although ORIF in condylar head fractures in adults and condylar fractures in children with mixed dentition is highly recommended, but this recommendation requires further investigations.

Determination of the external forces applied to the mandible during various static chewing tasks

The purpose of this study is to determine the external forces that are brought to bear on the mandible during 14 masticatory tasks, exerted in three defined mandibular positions. A static two-dimensional mandibular model is presented, taking into account projections in the sagittal plane of the forces exerted by six muscle groups and the joint reaction force. In calculating these external forces, two working hypotheses are adopted: the existence of a linear relationship between cross-sectional surface of the muscle and its maximum force of contraction, and the existence of a linear relationship between the electrical signal emitted by a muscle and the force the muscle then develops. Our first results are provided and compared with data from the literature. Individual variations recorded in the measurement of the different parameters involved in the equilibrium equations are such that they must be taken into account in the calculation of the forces. Moreover, the functional value of the muscles appears to be closely dependent on the mandibular position with which they are associated, which is not brought out in earlier studies. Finally, intra-joint action proves to be intense, although its direction varies according to the mandibular position and the type of exercise performed.

A novel navigation system for maxillary positioning in orthognathic surgery: Preclinical evaluation.

Appropriate positioning of the maxilla is critical in orthognathic surgery. As opposed to splint-based positioning, navigation systems are versatile and appropriate in assessing the vertical dimension. Bulk and disruption to the line of sight are drawbacks of optical navigation systems. Our aim was to develop and assess a novel navigation system based on electromagnetic tracking of the maxilla, including real-time registration of head movements. Since the software interface has proved to greatly influence the accuracy of the procedure, we purposely designed and evaluated an original, user-friendly interface. A sample of 12 surgeons had to navigate the phantom osteotomized maxilla to eight given target positions using the software we have developed. Time and accuracy (translational error and angular error) were compared between a conventional and a navigated session. A questionnaire provided qualitative evaluation. Our system definitely allows a reduction in variability of time and accuracy among different operators. Accuracy was improved in all surgeons (mean terror difference = 1.11 mm, mean aerror difference = 1.32°). Operative time was decreased in trainees. Therefore, they would benefit from such a system that could also serve for educational purposes. The majority of surgeons who strongly agreed that such a navigation system would prove very helpful in complex deformities, also stated that it would be helpful in everyday orthognathic procedures.