Juergen Zix 2007
Juergen Zix 2007
Juergen Zix 2007
65:1758-1763, 2007
3-dimensional (3D) miniplate for open reduction and monocortical fixation of mandibular angle fractures.
Patients and Methods: In 20 consecutive patients, noncomminuted mandibular angle fractures were
treated with open reduction and fixation using a 2 mm 3D miniplate system in a transoral approach. All
patients were systematically monitored until 6 months postoperatively. Among the outcome parameters
recorded were infection, hardware failure, wound dehiscence, and sensory disturbance of the inferior
alveolar nerve.
Results: The mean operation time from incision to wound closure was 65 minutes. Two patients had
a mucosal wound dehiscence with no consequences. None developed an infection requiring a plate
removal. All but 2 patients had normal sensory function 3 months after surgery. Plate fracture occurred
in one patient in whom a preceding surgical removal of the third molar had been the reason for the
mandibular fracture. In the absence of clinical symptoms, the patient declined plate removal. On final
follow-up, fracture healing was considered clinically complete in all patients.
Conclusions: The 3D plating system described here is suitable for fixation of simple mandibular angle
fractures and is an easy-to-use alternative to conventional miniplates. The system may be contraindicated
in patients in whom insufficient interfragmentary bone contact causes minor stability of the fracture.
2007 American Association of Oral and Maxillofacial Surgeons
J Oral Maxillofac Surg 65:1758-1763, 2007
Methods for open reduction of mandibular fractures
have changed and diversified enormously in recent
decades, but there is still controversy regarding the
optimal treatment.1 Today, open reduction and rigid
internal fixation can be achieved with a variety of
different plating systems, some using an intraoral approach and some an extraoral approach. The majority
of simple, nondisplaced or minimally displaced fractures of the symphysis, parasymphysis, and mandibular body can be adequately treated by osteosynthesis
with 1 or 2 miniplates. Fixation of more complex
0278-2391/07/6509-0014$32.00/0
doi:10.1016/j.joms.2007.03.013
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ZIX ET AL
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necting cross struts and the bars was 0.8 mm. The
length of the bars was 5 mm for the straight plate, and
1 mm for the upper border and 2 mm for the lower
border of the curved plate. All plates were placed
near the tension trajectories of the mandible. The
interconnecting cross struts were placed parallel, toward the fracture line.
Indications for tooth extraction were extensive
periodontal damage and fracture of the root. Because
none of the teeth in the fracture line met these criteria, no extractions were necessary. Concomitant fractures of the mandibular symphysis, parasymphysis, or
body were fixated with 2 4-hole 2 mm miniplates at
the superior and inferior borders. In cases of malocclusion, soft elastics were used to help correct the
occlusion. Concurrent condylar or subcondylar fractures were treated closed by postoperative intermaxillary fixation for 21 days. Drains were not used in any
of the patients.
For antibiotic prophylaxis, amoxicillin/clavulanic
acid 1.2 g was administered 3 times per day intravenously from admission up to 24 hours postoperatively, and 1 g 2 times per day orally for an additional
4 days. The patients were advised to rinse their mouth
3 times daily with a 0.1% chlorhexidine solution until
removal of the arch bars. Soft diet was strongly recommended for 6 weeks postoperatively.
Panoramic radiographs for evaluation of adequacy
of surgical reduction and plate localization were taken
before discharge (Fig 2). Planned follow-up intervals
were 1, 2, 6, and 12 weeks postoperatively. Postsurgical complications, defined as a need for further
intervention, were recorded prospectively over a
time span of at least 6 months postsurgery.
Results
The mean age of the 17 male (85%) and 3 female
(15%) patients was 33.9 years (range 18 to 59 years).
Most of the patients (85%) were fully dentate. Three
patients were partially dentate and none were edentulous. Interpersonal violence was the most common
etiology (35%), followed by falls (20%), car accidents
(15%), fractures following tooth extractions (15%),
and skiing or cycling accidents (10% and 5%, respectively). The mean duration from trauma to admission
was 25.3 hours (range 2 hours to 156 hours), and the
mean interval from trauma to surgery was 51.7 hours
(range 8 hours to 168 hours).
Radiologically, the dislocation of the fractures was
judged as severe in 2 cases, moderate in 2 cases, and
minimal in 16 cases. A concomitant fracture was
present in 8 patients (40%). The second most common fracture was at the contralateral parasymphysis
(5 patients), followed by condylar fracture (2 patients) and fractures of the mandibular body (1 patient). In 14 patients (70%) a molar was present in the
line of fracture, but in none of the cases was it necessary to remove the tooth during the operation. The
mean operation time from incision to wound closure
was 65 minutes (range 45 min to 110 min). Ten of the
fractures were treated with the curved 3D miniplate
and ten with the straight 3D miniplate. Two patients
with associated condyle fractures were treated with
subsequent maxillomandibular fixation for a mean
period of 21 days. Guiding elastics were used postoperatively in 4 patients in order to adjust the occlusion.
Postoperatively, none of the patients developed an
infection. Two patients with a mucosal wound dehiscence had to be treated with local chlorhexidine
rinsing, but there were no further consequences. In a
37-year-old male patient treated with the straight 3D
plate, a plate fracture occurred. In this particular case,
the angular fracture had occurred 5 days after a surgical removal of a third molar without any additional
trauma. The plate fracture was radiologically detected
6 weeks postoperatively. Postoperative panoramic radiographs with the straight 3D plate in place taken at
the immediate postoperative stage and 4 weeks postoperatively are shown in Figures 3A and B. Clinically,
however, the patient had no symptoms, and he therefore declined removal of the plate. In the group
treated with the curved strut plate, no hardware complications were seen. No case of non- or malunion
was recorded. For clinical assessment of fracture healing and condition of the hardware a routine plate
removal was aspired in all cases but was refused by 9
patients. For all 11 patients who underwent plate
removal, complete bone healing was observed at the
fracture site (Fig 4).
The function of the inferior alveolar nerve was
preoperatively examined in 16 patients. In the remaining 4 patients, preoperative sensory testing was
not possible due to their impaired medical condition.
Preoperatively, 6 patients had sensory deficits due to
their injury. Two patients with normal preoperative
ZIX ET AL
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conventional miniplates. The authors emphasized
that the strut plates have some hardware-related advantages over conventional miniplates and reconstruction plates. One advantage is easy application,
which avoids a time-consuming extraoral approach
and associated complications. Another advantage is
simplified adaptation to the bone, without distortion
or displacement of the fracture, as well as the simultaneous stabilization at both the superior and inferior
borders, making the 3D plates a time-saving alternative to conventional miniplates.11 In the study by
Feledy et al,14 as well as in our study, the easier
application was reflected in a reduced average operating time (55 and 65 minutes, respectively).
Another advantage of 3D plates is their improved
biomechanical stability compared with conventional
miniplates. The first biomechanical study of 3D plates
was conducted by Farmand.11 Unfortunately, very little information is available about the type of plates
used in this experimental study in pig mandibles.
Farmand found that the 3D 1 mm plate was as stable
as the much thicker 2-0 miniplate (Steinhuser plate),
which is designed for 1-plate fixation of mandibular
fractures, because the overall stability of the Steinhuser plate was limited by the stability of the screw
bone interface. Feledy and coworkers compared the
3D matrix plate (Synthes) with paired miniplates in a
sensation developed sensory deficits after the operation. All but 2 patients had normal sensory function of
the inferior alveolar nerve 3 months after surgery. The
2 cases with remaining hyposensibility had had a
severe traumatic dislocation of the fracture.
Discussion
The use of 3D miniplates in mandibular fracture
fixation has not yet become established. In a recently
published survey of 104 North American and European AO/ASIF surgeons, only 6% stated that they use
this type of plate.1 Only 4 studies presenting either
biomechanical or preliminary clinical findings with
this plate type have been published.11,13-15 Of these,
only 2 reported clinical outcome of fracture fixation
specifically of the mandibular angle.14,15 Guimond et
al15 and the work group of Feledy14 evaluated their
clinical results of the use of curved 2 mm angle strut
plates (Synthes, Paoli, PA) in 37 and 22 patients,
respectively. To our knowledge, ours is the first report on the clinical use of a different 3D miniplate of
the Universal Mandibular Plating System (Stryker/
Leibinger, Freiburg, Germany).
Both previous studies on the use of the curved 2
mm angle strut plate for angular fracture treatment14,15 reported low complication rates and concluded that the 3D plate is a predictable alternative to
1762
biomechanical experiment, and found better bending
stability and more resistance to out-of-plane movement in the 3D plating system.14
It has been claimed that mobility of fragments is a
causative factor in postoperative infections. Because
infection is the most common complication in mandibular fractures, the improvement of plate stability
might be a way to minimize this problem.3,16 With the
use of open reduction and internal fixation, the reported incidence of infection ranges from 3% to
32%.9,17 Infection rates in the clinical studies on 3D
plates are 5.4% (2 out of 37)15 and 9% (2 out of 22),14
which is in the normal range of current standards of
care in managing angle fractures. Hence, taking into
account the small number of patients treated in our
study, the infection rate of 0% is very favorable.
In addition to infection, sensory deficit is a problem
frequently seen in connection with mandibular fractures. In our study, a sensory deficit was related to the
injury in 75% of the observed cases, whereas only 25%
were caused by the treatment. This agrees with another study on 3D plates, which also found that the
main cause of sensory deficit in mandibular angle
fractures was the trauma itself.15 The most probable
reason for intraoperative damage to the nerve is fracture manipulation, rather than drilling and screw
placement close to the nerve. In our study the nerve
function recovered within the first 3 months after
surgery. Only in 2 cases with severe traumatic dislocation of the bony fragments was persistent sensory
dysfunction noted on final follow-up. This is consistent with previous studies, which found that the incidence of persistent inferior alveolar nerve deficits is
related to the degree of fracture displacement.15,18
The most important complication observed in our
study was a fracture of a straight 3D plate. Such a
plate failure was not observed in the previous studies
on the curved 2 mm angle strut plate.14,15 In analyzing
the cause of plate fractures, several factors have to be
considered. Besides the technical aspects, such as the
material and the form of the plate, there are some
surgical factors which contribute to weakening of a
plate. Multiple bending and improper placement of
the plate, as well as insufficient fracture reduction or
overdrilling of the screw holes, have negative effects
on the stability of the fixation, resulting in a plate
fracture.14,19
In our patient in whom a mandibular fracture had
occurred after a third molar removal, however, the
reason for the hardware failure most likely lies in the
reduced interfragmentary cross-sectional bone surface at the fracture site. A significant amount of contact surface is lost by removal of a tooth from the
fracture line itself, and this contact is additionally
reduced by associated removal of bone around the
third molar to be extracted. The stability of the frac-
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