MANAGEMENT OF MALUNITED BILATERAL ANGLE FRACTURE – A CASE REPORT

Dr Mahesh Kumar
R, MDS,
Reader

Dr Umashanker
D N, MDS
Senior Lecturer

Dr Vinay N Kashi
(PG Student)

Introduction

Some of the most severe injuries are caused by automobile accidents but many others result from interpersonal violence, industrial accidents, sports, home accidents and missiles or gun shots. Road traffic accidents (RTA) have been reported as a leading cause of mandible fractures1. Being the most prominent mobile bone of the facial skeleton, Mandibular fractures are among the most common injuries to the facial skeleton, with a 6:2 proportion between mandibular and zygomatic fractures 2, 3, 4. Majority of the mandibular fractures occur in young males5. In general, incidences of fractures of the mandibular body, condyle, and angle are relatively similar, while fractures of the ramus and coronoid process are rare. The literature suggests the following mean frequency percentages based on location: Body - 29%, Condyle - 26%, Angle - 25%, Symphysis - 17%, Ramus - 4%, Coronoid process - 1% The mandible is involved in 70% of patients with facial fractures. The number of mandible fractures per patient ranges from 1.5-1.8. Approximately 50% of patients with a mandible fracture have more than 1 fracture. Angle fractures occur in a triangular region between the anterior border of the masseter and the posterosuperior insertion of the masseter. These fractures are distal to the third molar. Usually an angle fracture on one side is accompanied by a contralateral condylar or parasymphyseal fracture. It is very occasionally that we encounter a bilateral angle fracture.

Case report

A 25yr old male patient reported to our department with a chief complaint of pain and inability to close his mouth

Fig 1: pic showing inability to close his mouth

The patient revealed that he had met with an accident about 3 months ago , for which he received only primary care and could not get proper treatment due to financial constraints. Detailed clinical examination revealed that the patient was unable to close the mouth nor could he chew any food & radiographic examination with orthopantamograph and mandibular occlusal films, revealed bilateral angle fracture with mid symphysis fracture. The fractured segments were not mobile. The fractured segments were horizontally unfavourable bilaterally. The proximal segments were seen to be superiorly displaced and were overriding the distal

Fig 2: OPG showing bilateral angle fracture

He also revealed that the patient had sustained injuries on his right ear. His right external ear had been sutured during primary care causing obliteration of the external acoustic meatus. He also had lost the upper part of the helix and was unable to hear from the right side

Fig 3: obliteration of external auditory meatus

The patient had developed an anterior open bite due to posterior dental contact because of which he was unable to close his mouth completely. He also had limited mouth opening due to long standing nature of the fractured segments. Open reduction internal fixation was planned under general anesthesia. Submandibular approach was employed to gain access to the fracture site. The skin incision was 4 to 5 cm in length, 2 cm below the angle of the mandible. Dissection was carried out through the subcutaneous fat, superficial fascia, platysma and deep cervical fascia to reach the inferior border of the mandible. Fracture site was identified and the segments were osteotomised and reduced. Soft tissue in between the fractured segments was removed and the margins were freshened using a bone trimming bur. A hole was made in the lower border of the proximal segment using a 702 bur. A 26 gauge stainless steel wire was passed through the hole, it provided us with downward traction of the proximal segment and also helped us stabilise the segment during plating

Fig 4: stainless steel wire passed to hold segments in place

A similar procedure was performed on the contralateral side to gain access to the fracture site. Occlusion was achieved and intermaxillary fixation was done with the help of arch bars which were placed preoperatively on the upper and lower arches. Due to long standing nature of the fractured segments, it was decided that just one plate would not be sufficient to counter the muscular forces; hence we decided to use 2 plates, one at the lower border and another parallel to it at the upper border. The fractured segments were fixed using two 2mm 5 holed continuous titanium mini-plate and eight 2 by 8 mm screws bilaterally

Fig 5, 6 & 7: fractures fixed bilaterally using 2 mm minipplates.

The mid symphysis fracture was not treated because the fragments were undisplaced and they had a good bony union. The closure was done in two layers using 3-0 vicry and 4-0 ethilon suture material. IMF was released.

As the opening for external acoustic meatus had been obliterated, a stab incision was placed in the external ear overlying the meatus. It was gradually enlarged till the entire opening was visible. Hemostasis was achieved using bipolar electrocautery. A gauze peanut was placed in the opening and a dressing was given to the ear. Postoperatively the long bones, AO initially stressed the need for absolute stability to prevent fragment mobility and generate primary bone healing14, 15. Reconstruction plates, lag screws, and 2-plate systems were all developed to achieve primary bone healing. The original AO technique involved placement of superior and inferior border compression plates for angle fractures13. We had to employ this method of plating using mini plates because there was malunion among the fractured segments, which were 3 months old. The fracture lines were unfavourable in both horizontal and vertical directions, in order to counteract the muscular pull by the pterygomassetric sling, it was decided to apply the 2 plate system.

The stability of single miniplate fixation of angle fractures was challenged by several biomechanical studies based on 3D models. Kroon et al and Choi et al both observed bony gaps along the inferior fracture border, and this fracture movement was thought to contribute to subsequent complications, including infection. A second plate was suggested to reduce anterior-posterior separation of the fracture line as well as lateral displacement, which is frequently observed on postoperative radiographs. Ensuing clinical studies were inconsistent, with an additional miniplate lowering, increasing, or not changing complications rates. More recent 3D models have shown that the rotational or torsional forces at the angle are relatively weak. Malunion is defined as complete healing in improper positions possibly precipitating clinical malocclusion. In the treatment of mandibular fractures, the most common complication cited in patient was able to hear well (FIG 8).

Fig 8: opening for external acoustic meatus created

Discussion Mandibular fractures are mostly described by anatomic location in the mandible and whether they are displaced, comminuted, or “greenstick.” They may also be classified as either favorable or unfavorable, based on the location and configuration. Favorable fractures are those that are nondisplaced. Angle fractures that extend posteriorly and downward are horizontally unfavorable and tend to be displaced by the muscles of mastication. Angle fractures are often unfavorable because of the actions of the masseter, temporalis, and medial pterygoid muscles, which distract the proximal segment superomedially. Fractures of mandibular angle are common6, 7. Reasons for this may include a thin cross-sectional area relative to the body, symphysis and parasymphysis anteriorly, the presence of the third molars and Abrupt change in direction between the body and ascending ramus in two planes8 , 9. Treatment of angle fractures is plagued by the highest complication rates among mandible fractures, and no consensus exists regarding optimal treatment10, 11, 12, and 13. As a result of early research in the literature is infection followed by malunion. Malunion occurs in two conditions, either after treatment due to inadequate reduction, inadequate stabilisation and fixation, development of infection or a combination of these or else when the patient has had no treatment at all for the fractured mandible. The latter was the reason for malunion in this case.

Conclusion

Though there are many treatment options available for the angle fractures, bilateral malunited angle fracture poses a unique challenge to the surgeon because fixation according to champy’s lines would just be insufficient to achieve a good stable occlusion. Through this case report we have put forth our line of treatment with which we were successful in obtaining a good occlusion and adequate mouth opening.

References

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