EVALUATION OF COMPLICATIONS AFTER ENDOSCOPY ASSISTED OPEN REDUCTION AND INTERNAL FIXATION OF UNILATERAL CONDYLAR FRACTURES OF THE MANDIBLE. RETROSPECTIVE ANALYSIS 2010–2015

INTRODUCTION

The beginning of endoscopy in medicine dates back to the first half of the 19^th century and it is associated with the name of Philippe Bozzini, who developed a primitive endoscope for examination of urethra, rectum, nasal airways, oral cavity and ear. Endoscope in maxillofacial surgery found its place in arthroscopy (endoscopy of temporomandibular joint), sinusoscopy (endoscopy of paranasal sinuses) and sialoendoscopy (endoscopy of salivary glands).

Endoscopy in traumatology of facial skeleton has been used for treatment of condylar fractures of the mandible and also for treatment of orbital base fractures.

Condylar fractures of the condyle belong to the most common types of fractures of the facial skeleton; they comprise 20–50% of fractures of the mandible.¹ There are common fractures of the head of the joint (intracapsular), at the site of the condyle (condylar) and base of the condyle (subcondylar).¹

Treatment of these fractures is conservative (intermaxillar fixation for 10–14 days with subsequent rehabilitation) or surgical (using stable osteosynthesis). Both methods have currently their advocates and opponents, whereas the main argument against open surgery is a real risk to injure the facial nerve.² This risk is minimized by the intraoral approach, when reduction and fixation of the fracture is performed with the assistance of an endoscope. The first publication about endoscopy assisted open reduction and internal fixation (EAORIF) of the condylar fractures of the mandible comes from Germany from 1996 (Mokros and Erle) and from USA from 1998 (Lee).^3,4

Authors of this paper present their experience with treatment of condylar fractures of the mandible with endoscopy assistance in a group of 33 patients, who underwent this type of operation at the First Faculty of Medicine of Charles University and General University Hospital in Prague (Stomatology Department, Department of Maxillofacial Surgery).

MATERIAL AND METHODS

During the period of 2010–2015 there were totally 95 patients who sustained a condylar fracture of the mandible treated with open surgery with subsequent osteosynthesis. EAORIF was used in 33 patients (34%). The remaining 52 patients were treated from retromandibular, subangular or endaural approach.

The criterion for indication of EAORIF was localisation of the fracture, while all the cases were of subcondylar type (Fig. 1); furthermore also the presence of only unilateral condylar fracture and also consent of the patient with this method. From the total number of 33 patients there were 10 men and 23 women; the average age was 36.4 years (19–68 years). 15 patients had also another fracture of the mandible (in 8 patients the angle of the mandible, in 7 cases body of the mandible).

Endoscopy assisted osteosynthesis of the condylar fracture of the mandible

The authors of this paper used specialized osteosynthetic instrumentarium (Synthes Company, Switzerland), and also an endoscope with optics with a diameter of 4 mm with angulation 30° (Karl Storz Company, Germany) (Fig. 2). The surgical procedure was performed from intraoral approach; an “S” incision in the retromolar area on the side of the fracture was performed; then the insertion of masseter muscle was released; subsequently was introduced an endoscope on the lateral side of the ramus mandibulae and under direct visualisation were identified fragments of the fracture. Their reduction followed. Fixation of fragments of the fracture was performed always with rigid intermaxillary fixation, and there were totally six miniscrews used that were introduced to the alveolus of the upper and lower jaw in all cases; screws were connected together with a wire loop. Miniplate was introduced to the fracture line intraorally; drilling of the holes for miniscrews took place through transbucal trocar with subsequent introduction of the miniscrews. (Fig. 3). At the end of the operation was removed rigid intermaxillar fixation by the removal of the wire loops. Fixation screws in the alveolus were kept.

Postoperative care

After operation was performed adhesive tape fixation of the face to reduce postoperative swelling, which was removed 24 hours after the procedure. The authors used a simple elastic intermaxillary fixation in all cases (elastic tractions were placed on fixation screws in the alveolus), which was kept in the patient until the 7^th postoperative day. Fixation screws were also removed with removal of elastic tractions. Rehabilitation of mouth opening started after removal of elastic intermaxillary fixation (i.e. 8^th postoperative day, when the patient underwent rehabilitation of mouth opening for the subsequent 3 weeks (opening of mouth at least 5 times a day for 5 minutes to the pain level. From the 6th week the patient underwent rehabilitation of symmetrical mouth opening (using isometric exercises).

Every patient starting from patient number 15 received a suction Redon drain to the surgical wound, which was removed 24 hours after the operation.

Evaluation of results

Evaluation of reduction and fixation was performed on the 1st postoperative day based on X ray pictures (panoramatic image and postero-anterior image of the skull). (Fig. 4–7.) Reduction of fragments was evaluated as anatomical (fragments are in ideal position), physiological (fragments are in appropriate position, however there may be displacement of fragments up to 2 mm) and malposition (when fragments are displaced more than 2 mm, or in very inappropriate position, when height of the condyle of the mandible was not restored, or displaced fragment with joint head was not reduced to the socket).

Surgical time and presence of complications were also evaluated.

Evaluation of complications was divided to:

• intraoperative complications: bleeding, loss of osteosynthetic material (evaluated all 33 patients)
• postoperative complications: wound infection, prolonged healing, injury to the facial nerve, change of occlusion, presence of salivary fistula. Evaluation of postoperative complications was performed for the period of first 12 months after operation (evaluation of 30 patients).

Furthermore, there was function of temporomandibular joint (TMJ) evaluated in 12 months after osteosynthesis (evaluation of 30 patients), while maximal opening of the mouth was recorded (measured between incisive teeth) with symmetry of opening and also presence of pain or pathological sound phenomena.

RESULTS

Between 2010 and 2015 there were 33 patients treated with EAORIF, in all cases for subcondylar fracture, while the type of displacement was:

• shortening of the height of ramus mandibulae with displacement of the proximal fragment laterally (dislocatio ad longitudinem cum contraction – 20 patients)
• displacement with angulation of the proximal fragment (dislocatio ad axim – 13 patients); in 4 patients there was medial angulation, in 3 there was distal angulation and in 6 patients there was ventral angulation of the fragment.

Surgical time:

Average: 100 minutes (60–198 minutes)

Average surgical time in 2010–2012: 123 minutes

Average surgical time in 2013–2015: 77 minutes

Evaluation of fragment reduction:

Anatomical: 22 patients (67%)

Physiological: 9 patients (27%)

Malposition: 2 patients (6%)

One patient with malposition was reoperated, one patient refused reoperation after considering the condition to be satisfactory.

Malposition was reported in two cases in patients with medial dislocation of proximal fragment.

Usage of a plate:

1 direct plate: 19 patients (58%)

2 direct plates: 2 patients (6%)

Lambda type of plate: 5 patients (15%)

Lag screw: 4 patients (12%)

Trapezoid type of plate: 3 patients (9%)

Evaluation of stability of occlusion (12 months after operation, 30 patients): 29 patients with stable occlusion; in one patient was reported opening of occlusion on contralateral side, according to the follow up CT due to condylar absorption).

Intraoperative complications:

Bleeding: 1 patient (3%)

Loss of osteosynthetic material (miniscrew): 1 patient (3%)

Bleeding was stopped with a tamponade using hemostatic material introduced behind the edge of the mandible.

Postoperative complications:

Facial nerve palsy: 4 patients (12%); restoration in 3 patients within 2 months, and in 1 patient within 6 months.

Inflammatory complications: 3 patients (9%), in all cases this was infection of a hematoma. After that we started using a suction drain for 24 hours after the operation (from the patient No. 15). No more such complications were reported since then.

Muscle pain (pain and occasional cramps of the masseter muscle): 4 patients (12%); duration of complaints was reported within 6 months after the procedure.

Evaluation of TMJ function:

12 months after the operation (evaluation of 30 patients). Abduction: in all patients above 35 mm, average level: 39 mm (35–49 mm).

Symmetry of opening: in 26 patients (86%) symmetrical abduction, in 4 patients (14%) abduction with deviation to the affected side.

Pain in TMJ was not reported in any patient. Sound phenomena (crackles) were present in two patients, whereas both patients reported presence of these sounds also at the time before trauma.

DISCUSSION

One of the therapeutic options to treat condylar fractures of the mandible is conservative therapy (short term intermaxillary fixation with subsequent rehabilitation). It is suitable in non-dislocated types of fractures; it is associated with several disadvantages in case of dislocated fractures: malocclusion, alteration of physiological function of the joint, increased risk of joint ankylosis, facial asymmetry due to shortening of the ramus mandibulae. In condylar fractures, there was remodelation capability reported, however, it is present mainly in paediatric patients and this capability declines with increasing age¹.

The second therapeutic option to treat condylar fractures is surgical therapy, which is based on reduction of fracture fragments to anatomical position and their fixation with titanium miniplates. This restores occlusion and full function of the TM joint. The main disadvantage of open surgery is a risk to injure facial nerve and also an aesthetic handicap - postoperative scar in visible parts of the face or neck. This risk minimizes the use of intraoral approach, when there is a however limited view and in most cases it is necessary to use an endoscope to visualize the fracture, perform reduction and fixation.^1,2,5 The results of EAORIF (satisfactory position of fragments, stable occlusion and function of TMJ) are comparable in literature with the use of other surgical approaches.^5–12 Authors of this paper achieved anatomical reduction in 67%, physiological reduction in 27% of patients. Only in 2 patients (6%), reduction and fixation was not satisfactory. These were one of the first patients from the study group, who underwent EAORIF and this fact may be related with lesser experience of the surgeons.

Function of TMJ was not limited in any case; the average mouth opening was 39 mm, whereas one year after the operation was abduction of the jaw symmetrical in 86% of patients, with even movement of both condyles. Pain in TMJ was not reported. The extent of opening and symmetry of movement of the mandible is related with the necessary postoperative physiotherapy and it is greatly associated with cooperation of the patient.

The stability of occlusion after operation is related in literature with the stability of osteosynthesis.^1,5 As an adequate osteosynthesis of the condylar fractures of the mandible is recommended usage of 2 direct miniplates, while one of the plates is fixed along the axis of the condyle at the posterior edge of the mandible (for compensation of compressive forces that develop during mastication) and the second plate is fixed on the anterior edge of the condyle (for compensation of tension forces).^1,12,13 Usage of 2 direct miniplates during EAORIF is usually very difficult and relates with the experience of the surgical team. The authors of this paper used 1 direct plate in most cases (58%), 2 direct plates only in 2 patients (6%). The same effect as in 2 direct miniplates was achieved in plates of Trapezoid type (Fig. 8) and Lambda type (Fig. 9), which are adjusted in shape to compensate the forces that occur during mastication. In the presented group were the special Trapezoid and Lambda plates used in 30% of patients. In 4 patients (12%) was fixation performed with 2 lag screws (Fig. 10). However, lag screws may only be used in sheet fractures.¹Although the authors of this paper used several types of osteosythetic material, osteosynthesis of the fragments was stable in all cases. Evaluation of occlusion (12 months after operation in 30 patients) has shown no changes in 29 patients. Only in 1 case (2%) was obvious gradual development of open bite. This was not however due to failure of osteosynthetic material, but due to the development of condylar absorption probably due to uni-lateral overload of the joint structures during a trauma with development of subsequent subchondral necrosis.

The disadvantage of EAORIF is the need to use specialized instrumentarium: retractors, reduction hooks and last but not least an endoscopic set. Another disadvantage of EAORIF is surgical time, which is longer than in standard open operation.⁹ The average surgical time in our case was 100 minutes, while average surgical time is generally reported as shorter, 50–80 minutes.^{5,10,11,13,14} Authors of this paper suggest that this is due to the initially lower experience of the surgical team. Between 2010 and 2012 was the average surgical time 123 minutes, between 2013 and 2015 there was significant reduction of average surgical time – to 77 minutes.

Indication for EAORIF is mainly subcondylar fracture. Schon characterizes as an indication criterion the possibility to insert at least 2 screws to the proximal fragment (which is needed for fixation with a miniplate).^1,10,11 Type of displacement of proximal fragment is not a limitation in the indication of EAORIF^5,9–12, however the authors of this paper clearly recommend EAORIF method for the type of subcondylar fracture with shortening of the height of the ramus mandibulae with displacement of proximal fragment laterally.

Generally there are minimal complications associated with EAORIF, however the following are reported - facial nerve palsy, wound infection, salivary fistula, impaired healing, bleeding, failure of osteosynthetic material, change of occlusion, disorder of TMJ.^{1,10,11,13,14,16} Kang reports that occurrence of complications rises with increasing age.¹⁷ In our group there was bleeding reported in one case and loss of osteosynthetic material – miniscrew – in one case.

Bleeding occurs usually from intraoperative retromandibular vein or branch of maxillary artery. Bleeding may be stopped with compression using haemostatic material – in case of bleeding from retromandibular vein. In case of bleeding from the branches of maxillary artery is compression with hemostatic material usually not sufficient and there is a need to perform ligation of the bleeding vessel (from the posterior approach), rarely, however, must be performed ligature of external carotid artery.^1,16,18

Management of loss or dislocation of osteosynthetic material is usually based on performance from the external approach and removal of material from the wound. In one patient from our group, it was possible to identify the position of a lost miniscrew only with intraoperative X ray examination, but the patient refused further surgical intervention and miniscrew remained in the surgical wound. 12 months after operation the miniscrew did not cause any problems and did not influence healing.¹

Facial nerve palsy in association with EAORIF is reported as temporary and develops mainly due to contusion of the nerve by pulling soft tissues with retractors during operation.^{1,3,5,10,11,19} In our paper was reported temporary disorder of facial nerve function in 3 patients (12%). Impaired function of other cranial nerves was not reported in the studied group by the authors.

Infectious complications do not belong to common complications. Prade reports 3 in 25 patients after surgery.⁸ In our group was reported in 4 of 33 patients (12%). In all cases it was infection of a hematoma. After using suction drains for 24 hours after the operation, there were no more complications reported.

Muscle pain may occur due to trauma of a muscle and its subsequent scaring, which could cause development of muscle spasms. Authors of this paper observed this in 6 cases and always in operations where surgical time exceeded 150 minutes. Prevention of this complication is careful muscle stretching in the postoperative period.¹

Aesthetic handicap in terms of significant scar was not reported in any case, same as other authors. The risk of a scar is related with transbucal trocar, and this is a scar with a length of several milimeters.^{1,10,11,13,14,16} The need of transbucal insertion of a trocar is missing in the use of angulated instruments (screws and drills).^5,10,15

CONCLUSION

Endoscopy assisted open reduction and internal fixation is one of the therapeutic alternatives for condylar fractures of the mandible. Its consequences are comparable with classical surgical approaches, however it significantly minimizes the risk of facial nerve injury and last but not least also an aesthetic handicap - postoperative scar. Authors of this paper also recommend usage of a Redon drain for 24 hours after the operation as a prevention of infectious complication of the procedure. On the other hand, it requires endoscopy-assisted approach of an experienced surgical team and instrumentarium to perform the surgery. As in case of every technique, also here is obvious improvement of the results due to the learning curve.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of this article.

Corresponding author:

Vladimír Machoň, M.D.

Stomatology Department, First Faculty of Medicine Charles University and University Hospital in Prague

U Nemocnice 2, 120 00 Prague 2

Czech Republic

E-mail: machonv@seznam.cz