J Oral Maxlllofac 49.1247-1250.

Surg

1991

Auxiliary Devices for Open Reduction and Fixation of Displaced Mandibular Angle Fractures FRANK HALLING, MD, DMD,* HANS-ALBERT MERTEN, MD, DMD,* AND HANS GEORG LUHR, MD, DMDt Absolutely necessary preconditions for rapid healing of mandibular fractures are the anatomic reduction of the fracture ends and rigid fixation. These factors are well addressed by the compression screw system of Luhr’ with bicortically inserted, self-tapping screws applied via an intraoral approach.’ This technique helps to avoid occlusal disturbances and there is no need for postoperative maxillomandibular fixation (MMF). As long as fractures are located in dentulous mandibular segments, treatment usually presents no surgical problems. If a mandibular fracture is located outside the dental arch, however, special aspects must be taken into consideration. Whereas the tooth-bearing segment can be stabilized in occlusion by MMF, the proximal fragment easily dislocates, especially under general anesthesia and muscular relaxation. The following report describes useful supplements to our operative technique that includes simple devices to facilitate anatomic reduction and temporary fixation even in severely displaced unilateral or bilateral mandibular angle fractures. Operative

the intraoral application of a compression plate and screws is difficult in more distally located fractures, a stab incision for a transbuccal approach is made to allow percutaneous use of the surgical drill and the screwdriver. The fracture is now reduced under direct vision by means of different devices. Miniscrews 10 or 12 mm in length are inserted monocortically at least 5 mm distally and medially to the fracture line to ensure firm anchorage in the bone. The placement of the drill holes for the miniscrews at the upper border of the angle is carried out by means of an angled drill, whereas for the insertion of the screws the 90” screwdriver (Howmedica International, Inc) can be used very effectively. The working head of this instrument allows rotation of the screw at right angles to the screwdriver handle. Next, the ends of a 22-gauge wire are twisted with a plate bending plier and then looped in a figure of 8 (Fig 1A). The loops of the wire are passively placed around the screw heads, bridging the fracture site. The wire ends are now slowly twisted with a ligature forceps to draw the fragments together. This often produces excellent adaptation at the alveolar crest but gaping at the lower mandibular margin (Fig IA). However, as a result of the ensuing compression plating with bicortical screw fixation at the lower border of the mandible, the cleavage completely disappears (Fig IB). To prevent a lingual gap, the compression plate is overbent s1ight1y.3 After plating is completed, the temporary fixation device, the MMF, and the dental arch bars can be removed with subsequent free movement of the mandible. The so-called holescrew was especially developed for the application as a repositioning device (Fig 2A). It is characterized by a transverse drill hole that is located between the screw head and the thread. The drill hole, which can be created by means of a laser, allows the introduction of a 22gauge wire (Fig 2B). To facilitate handling, the drill

Technique

First, the occlusion is established by use of dental arch bars and MMF. Then, a buccal mucoperiosteal flap is reflected to expose the fracture site. Because

Received from the Department of Oral and Maxillofacial Surgery. University Clinic Goettingen, Goettingen, Germany. * Resident. t Professor and Chairman. Address correspondence and reprint requests to Dr Frank Halling: University Clinic Giittingen. Department of Oral and Maxillofacial Surgery. Robert-Koch-Str 40. D-3400 Goettingen. Germany.

icJ 1991 American geons

Association

of Oral and Maxillofacial

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0278-2391/91/4911-0024$3.00/O

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FIGURE I, A, Diagram of the situation after open reduction and temporary fixation of the fracture ends. The tightened ligature wire (top left. magnification of the figure-of-eight ligature) is twisted around two miniscrews beside the fracture line. Note the gap at the lower margin of the mandible (arrow). B, Bicortical compression screw plating at the lower border of the mandible is finished, the gap is closed (arrow).

hole is placed exactly one slot below the screw head. After exposure of the fracture site via an intraoral approach, two IO-mm holescrews are inserted in the buccal cortical layer on either side of the fracture line to a depth of 5 mm. The wire is placed through the drill holes of both screws and wound around the screw heads. Alternately tightening the screws with the 90” screwdriver closes the fracture gap step-by-step. After adaptation and temporary fixation of the fracture ends, rigid fixation is performed by compression screw plating. Subsequently the repositioning devices are removed and the MMF is released. In special types of fractures, eg, sagittally oblique fractures or fractures with bone defects in the alveolar region, the use of traction with screws and a wire ligature is not stable enough or impractical. In this situation, a miniplate can serve as an auxiliary device for repositioning and fixation of the fracture. Ideally, in jaw angle fractures, this plate is placed on the broad surface of the external oblique line as

high as possible4*5 (Fig 3). To minimize the danger of damaging neural structures or roots of teeth, only monocortical screws 6 or 8 mm in length are used. Under axial compression, the fragment ends are easily adapted. Consequently, the definite fixation with MCS-plates is facilitated. The miniplate can be removed at once or left in situ for the purpose of a tension band plate. In mandibular angle fractures in children, a microplate can be applied to gain a temporary fixation in the tension band line. Discussion In contrast to the conservative treatment of mandibular fractures, rigid intraoral fixation not only requires accurate establishment of occlusion, but also a most precise reduction of the fracture ends. In fractures located distal to the canines, the plate should be applied in a craniolingual position because this placement compensates for the tension

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FIGURE 3. Miniplate with monocortical screw fixation placed in the region of the external oblique ridge. The cleavage (exaggerated for demonstration) disappears after basal compression plating.

FIGURE 2. A. Ten-millimeter holescrew with a lasergenerated drill hole 0.5 mm in diameter below the screw head (original magnification K I I). B. Holescrew with inserted ligature wire.

forces region The ments toward gion.4

best. However, for anatomic reasons, this is unsuitable for plate osteosynthesis.’ forces acting on the mandible produce moof flexion that are predominantly strongest the angle and weakest in the premolar reDuring functional use of the mandible, the

alveolar region is additionally exposed to tractional forces and the lower border to forces of compression.* These forces. taken together, often result in a considerable cleavage in the upper portion of the mandibular angle that complicates the repositioning and internal fixation, even for experienced surgeons. We have used the described auxiliary devices with good results in over 50 mandibular angle fractures during the past 3 years. In contrary to conventional reduction forceps.’ these auxiliary devices allow an axially correct reduction and stable fixation without restricting the surgical field. The fixation in the alveolar region of the mandible prevents separation of the fragments during bicortical compression plating. Whereas intracortical wire ligatures for fixation often split the bone, ligatures secured by screws without direct contact to the bone withstand strong tractional forces. The clinical observation of secondary cleavage in the fracture line after temporary fixation in the alveolar region of the mandible (Figs IA and 3) coincides with the experimental findings of Kroon.” If the load is close to the fracture, the line of tension shifts from the upper to the lower border of the mandible and even a miniplate placed in the alveolar crest region is not rigid enough to prevent a gaping of the fracture line.” Rigid fixation and sufficient interfragmentary pressure can only be achieved by bicortical compression screw plating at the lower border of the mandible. Whether or not the additional miniplate remains in situ as a tension band osteosynthesis should be decided individually. Microplates, however, used as a temporary device for repositioning and fixation of mandibular angle fractures in children, always should be removed after fracture healing.”

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Acknowledgment The authors thank Lambda Physik Co, Gottingen. for the production of the holescrews with their laser equipment.

References 1. Luhr HG: Zur stabilen Osteosynthese bei Unterkieferfrakturen. Dtsch Zahnarztl Z 23:754, 1968 2. Luhr HG: Vitallium Luhr systems for reconstructive surgery of the facial skeleton. Otolaryngol Clin North Am 20:573, 1987 3. Schilli W: Compression plate osteosynthesis through the ASIF system, in Kruger E, Schilli W (eds): Oral and Maxillofacial Traumatology, vol 1. Chicago, IL. Quintessence, 1982,~~ 357,358 4. Cawood JI: Small plate osteosynthesis of mandibular fractures. Br J Oral Maxillofac Surg 23:77, 1985 5. Champy M. LoddC JP, Schmitt R. et al: Mandibular osteo-

6. 7.

8. 9. 10.

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synthesis by miniature screwed plate via a buccal approach. J Maxillofac Surg 6: 14, 1978 Luhr HG: A micro-system for crania-maxillofacial skeleton fixation. J Craniomaxillofac Surg 16:312, 1988 Niederdellmann H: Fundamentals of healing of fractures of the facial skull, in Kruger E, Schilli W (eds): Oral and Maxillofacial Traumatology, vol 1. Chicago, IL. Quintessence, 1982. p 130 Niederdellmann H, Akuamoa-Boateng E: Internal fixation of fractures. Int J Oral Surg 7:252, 1978 Spiessl B: Osteosynthese des Unterkiefers, vol I. Berlin, Springer, 1988. p 98 Kroon FHM, Matthison M, Cordey JR, et al: The use of miniplates in mandibular fractures. J Craniomaxillofac Surg 19:199. 1991 Hailing F. Merten HA, Wiltfang J, et al: Untersuchungen zur Unterkieferfraktur im Wachstumsalter und Spatergebnisse der operativen Therapie. Dtsch Zahnarztl Z 45:809. 1990