J Oral Maxillofac Surg 57:288-292, 1999

Treatment of Mandibular Angle Fractures with a Malleable Noncompression

Miniplate Jason Potter, DDS, * and Edward Ellis III, DDS, MSf

Purpose: This study evaluated the results in patients treated for fractures of the mandibular angle with a single, thin, malleable miniplate designed for use in the midface.

Patients and Methods: Forty-six patients with 51 fractures of the mandibular angle were treated by open reduction and internal fixation using one noncompression, thin, malleable miniplate and 1.3-mm self-threading screws placed through a transoral incision. No patient was placed into postsurgical maxillomandibular fixation. They were prospectively studied for complications.

Results: Seven patients (15.2%) experienced complications. All were considered minor and did not require hospitalization. Three had asymptomatic fracture of the bone plate, but at the time of diagnosis the fracture had already healed and it required no treatment. Two patients had fracture of the bone plate with continued fracture mobility requiring maxillomandibular fixation. Three minor infections occurred requiring intraoral incision and drainage.

Conclusions: The use of this small bone plate for fractures of the angle of the mandible provided adequate fixation in most cases but was associated with an unacceptable incidence of plate fracture. However, the results also indicate that the fixation requirements for angle fractures is less than previously thought.

A consecutive series of studies has indicated that, contrary to popular beliefs, the incidence of complica- tions after fractures of the mandibular angle are inversely proportional to the rigidity of the fixation applied. *-G Whenever two points of fixation were used for angle fractures, *s*,~ the complication rate was much higher than when one point of fixation was applied.‘x3,” This finding seemingly defies logic, be- cause conventional wisdom would indicate that more stable fixation should provide fewer complications. However, experience has shown the opposite. The use of a single, 2-mm noncompression miniplate was associated with much fewer complication& than when two plates were used, irrespective of whether they were compression or noncompression plates.2x4,s

Received from the University of Texas Southwestern Medical

Center, Dallas, TX.

*Resident, Oral and Maxillofacial Surgery.

tprofessor, Oral and MaxiUofaciaf Surgery.

Supported in part by a grant from the Chalmers J. Lyons-James R.

Hayward Research Fund.

Address correspondence and reprint requests to Dr Ellis: Division

of Oral and Maxillofacial Surgery, University of Texas Southwestern

Medical Center, 5323 Harry Hines Blvd, Dallas, TX 752359109;

e-mail: eellis@mednet.swmed.edu

D 1999 American Association of Oral and Maxillofaciol Surgeons

0278.2391/99/57030009$3.00/0

Therefore, the question that must be asked is how much fixation is enough for fractures of the mandibu- lar angle? LoddC has reduced the volume of the original Champy miniplate by half, making them much more malleable, and has not noted any increase in complications when they were used for mandibular fractures.’ The purpose of this investigation was to prospectively evaluate the use of a thin, malleable miniplate and 1.3~mm screws for stabilization of fractures of the mandibular angle (Pig 1). This plate was not designed for use in the mandible but was designed for use in the non-load-bearing regions of the midface.

Technique

After placement of arch bars, the fracture was exposed using an intraoral incision. Only the amount of soft tissue stripping necessary to visualize, reduce, and stabilize the fracture was performed. Mobile teeth or teeth whose apices were exposed in the fracture site were removed. If teeth in the fracture site were to be extracted, the intraoral incision included the at- tached gingiva around the involved tooth. The frac- ture was then reduced and the jaws placed into maxillomandibular fixation (MMF). A seven-hole non- compression titanium miniplate (Synthes Maxillofa- cial, Paoli, PA) was inserted along the medial side of

288

POTTER AND ELLIS 289

FIGURE 1. Photograph of 1 .3-mm adaptation plate [above) to 2.0mm miniplate plate [below).

the external oblique ridge and screwed to the bone using three 5 mm long, 1.3mm diameter self- threading screws on each side of the fracture (one hole was left empty over the fracture) (Pig 2). Because

of the thinness and malleability of the plates, it was unnecessary to bend them. Rather, the plates were coapted to the bone merely by tightening of the screws. Use of transbuccal trocar was unnecessary. After the plate was placed, MMF wires were removed, and the occlusion was checked. Postsurgical MMF was not used in any patient. The incision was closed with resorbable suture, and no drams were placed. Postsur- gical recommendations for soft diet were generally prescribed but, because of the noncompliant nature of the patients, probably rarely followed.

Patients and Methods

All dentate patients treated by the previous tech- nique between December, 1,1995 and August 1,1997

FIGURE 2. Example of a fracture of the right mandibular angle treated using a 1 .3-mm plate. A, Preoperative panoramic radiograph showing fracture through right angle. 6, lntraoperative photograph after placement of arch bars and exposure of fracture. C, lntraoperative photograph after removal of tooth in line of fracture, maxillomandibular fixation, and insertion of the bone plate. D, Panoramic radiograph taken 6 weeks after surgery, just before removal of arch bars.

290 TREATMENT OF MANDIBULAR ANGLE FRACTURES

with noncomminuted fractures of the mandibular angle, who had at least 6 weeks of follow-up, were included in this study. They were prospectively evalu- ated for the following information: 1) additional frac- tures; 2) presence of a tooth in the line of fracture; 3) extraction of tooth in line of fracture; 4) complica- tions during surgery; 5) postsurgical occlusal relation- ship; and 6) postsurgical complications, which were defined as a need for further surgical intervention.

Results

Forty-six consecutive patients, 37 males (80.4%) and nine females (M/F = 4: 1) with 5 1 angle fractures (five were bilateral), had sufficient follow-up for inclu- sion in this study. They ranged in age from 14 to 52 years, with a mean of 27.6 years. Twenty-four patients (52.2%) were black, 15 were Latin Americans (32.6%) and seven were of non-Hispanic origin (15.2%). The principal cause of the mandibular fractures were altercations (n = 33, 71.7%) followed by motor vehi- cle-related trauma (n = 9, 19.5%) sporting injuries (n = 3, 6.5%) and falls (n = 1, 2.2%). The angle fracture was on the left side in 21 patients (45.6%) on the right in 20 (43.5%) and bilateral in five (10.9%). Twenty patients (43.5%) had a mandibular angle fracture as their only fracture. The remaining 26 patients had at least one other fracture of the man- dible (56.5%). All other fractures were treated by a variety of stable plate or screw fixation techniques. No patient was placed into postsurgical MMF; all were allowed immediate mobilization.

The time from the initial injury to surgical treatment ranged from less than 1 to 10 days, with a mean of 3.6 days. One patient had surgery within 24 hours from the time of injury (2.2%); 12 patients between 1 and 2 days (26.1%); 22 patients between 3 and 4 days (47.8%) and 10 patients greater than 4 days (21.7%). Forty-three of the 51 angle fractures (84.3%) were associated with an impacted or erupted molar tooth. These were removed at the time of surgery in 34 (85%) of these fractures.

After application of the bone plate, all fractures appeared to be well reduced and stable. Postoperative radiographs taken within the first 2 days showed excellent reduction in all cases. Immediate occlusal relationships were judged as normal in all but one patient, whose mandible was shifted to the contralat- era1 side in association with moderate swelling of the right submandibular and lateral pharyngeal spaces due to infection of these spaces present before surgery. This resolved with the resolution of the infection and the use of light training elastics for 14 days. At the time of arch bar removal, one patient was judged to have a malocclusion that was attributed to malunion at a fracture site other than the angle. All other occlusal

relationships were judged normal. There was no clinical evidence of damage to the inferior alveolar neurovascular bundle from placement of the fixation hardware. The follow-up ranged from 6 to 52 weeks, with a mean of 11.9 weeks.

Seven patients (15.2%) developed complications from their angle fracture postoperatively, but only four (8.7%) required further surgical intervention. The mean age (32.3 years), time between injury and treatment (2 to 10 days; mean, 5.4 days), sex (6:l male/female), race, and association with impacted/ erupted molars in these patients was not significantly different than the entire population. All complications were considered minor and consisted of plate frac- ture, local infection, or both. Five patients developed fractured plates (10.8%). Three had asymptomatic fracture of the plate diagnosed on radiographs; how- ever, there was bony union of the fracture, and no intervention was required (Fig 3). Two patients had fracture of the plate with clinical mobility of the fracture and were placed into MMF for a period of 6 weeks. One of these patients subsequently developed a localized infection of a devitalized tooth in the line of fracture and was treated with oral antibiotics and extraction of the offending tooth. One patient devel- oped an isolated infection associated with a devital tooth that was treated by intraoral incision and drain- age, extraction of the tooth, and oral antibiotics without plate removal. One patient developed an isolated infection associated with loosening of the hardware several weeks after completing rehabilita- tion, and was treated with oral antibiotics and removal of the hardware under local anesthesia. No patient developed major complications that required hospital- ization or intravenous antibiotic therapy.

Discussion

After studying many alternate treatments for frac- tures of the angle of the mandible in our patient population, of all the intraoral techniques,1Ja4-6 a single 2.0-mm miniplate was associated with the fewest major complications7 Interesting, this was also the technique that was the least stable of the methods used. A single lag screw,l two compression plates,2,4 two miniplates and an A0 reconstruction plate3 are much more “rigid” forms of fixation than a single miniplate.

The apparent success of a single miniplate for fractures of the mandibular angle may seem incongru- ous with traditional principles of rigid internal fixa- tion. Proponents of rigid internal fixation believe that prevention of interfragmentary mobility is the key to success and should be sought when treating frac- tures.8-10 Clearly, a single 2.0-mm miniplate does not satisfy the requirements of a truly “rigid’ system. This

POTTER AND ELLIS 291

FIGURE 3. Case in which a complication occurred. A, Pan- oramic radiograph taken immedi- ately after treatment of bilateral angle fractures. 6, Panoramic ra- diograph taken 8 weeks later, just before arch bar removal. Note that the plate on the right angle has fractured, with minimal change in ramus nonmobi e and the occlusion was P

osition. The fracture was

normal for patient. The arch bars were removed, and the patient received no further treatment.

seeming dichotomy highlights the limitations of rely- ing on the results of biomechanical bench testing for clinical treatment recommendations. All biomechani- cal studies that have compared two-point fixation with one-point fixation have shown more stability with two.l’-‘3 In spite of this, our clinical results indicate fewer complications with single-point fixa- tion.

If less stability across an angle fracture meets with better clinical success, how much instability can be tolerated? The purpose of this investigation was to determine whether a very thin, malleable plate would be adequate for stabilizing angle fractures. A plate that was designed for non-weight-bearing fractures of the midface was chosen. The plate is extremely malleable and does not require adaptation to the underlying bone. Because of its small size and the small hole diameter for the screws (1.1 mm), the plate could be placed on top of the external oblique ridge if one chooses to do so. It is very fast to insert because no adaptation is necessary. One has only to drill a hole directly behind the fracture and insert the first screw through the plate in this location. The plate then can be rotated until it is in good position and the remain- ing screws inserted.

Our experience indicates that this plate provides

adequate fixation for most fractures of the angle. However, there was an unacceptable rate of plate fracture that, fortunately, did not lead to major compli- cations. Therefore, the plate cannot be recommended for routine use for fractures of the angle. However, clearly, even a 2.0-mm miniplate is over-engineered for angle fractures. We have never had a 2.0~mm miniplate break in this location. Although easy to adapt, a 2.0~mm miniplate still requires bending to the contours of the bone before placement. The advan- tage of a thinner, more malleable plate is that it requires less contouring and eases the application process. We therefore believe that a scaled-down 2.0~mm miniplate, or a thicker 1.5mm miniplate, would satisfy the requirements of sufficient fixation for fractures of the mandibular angle.

References 1. Ellis E, Ghali GE: Lag screw fixation of mandibular angle

fractures. J Oral Maxillofac Surg 49:234, 1991 2. Ellis E, Karas N: Treatment of mandibular angle fractures using

two mini-dynamic compression plates. J Oral MaxiUofac Surg 50:958, 1992

3. Ellis E: Treatment of mandibular angle fractures using the A0 reconstruction plate. J Oral Maxillofac Surg 51:250, 1993

292 DISCUSSION

4. Ellis E, Sinn DP: Treatment of mandibular angle fractures using two 2.4 mm dynamic compression plates. J Oral Maxillofac Surg 51:969, 1993

5. Ellis E, Walker L: Treatment of mandibular angle fractures using two noncompression miniplates. J Oral Maxillofac Surg 52: 1032,1994

6. Walker L, Ellis E: Treatment of mandibular angle fractures using one noncompression miniplate. J Oral Maxillofac Surg 54:864, 1996

7. Champy M, Kahn JL: Fracture line stability as a function of the internal fixation system: An in vitro comparison using a mandibular angle fracture model (Discussion). J Oral Maxitlofac Surg 53:801,1995

8. Spiessl B (ed): New Concepts in Maxillofacial Bone Surgery. Berlin, Germany, Springer-Verlag, 1976

9. Spiessl B: Internal Fixation of the Mandible. New York, NY, Springer-Verlag, 1989

10. Lubr HG: Compression plate osteosyntbesis through the Lubr System, in JSriiger E, Scbilli W (eds): Oral and MaxiUofacial Traumatology, ~011. Chicago, IL, Quintessence, 1982

11. Kroon FHM, Matbisson M, Cordey JR, et al: The use of miniplates in mandibular fractures. J Craniomaxillofac Surg 19:199, 1991

12. Shetty V, McBrearty D, Fourney M, et al: Fracture line stability as a function of the internal fixation system: An in vitro compari- son using a mandibular angle fracture model. J Oral Maxillofac Surg 53:791, 1995

13. Choi BH, Yoo JH, Kim RN, et al: Stability testing of a two- miniplate fixation technique for mandibular angle fractures: An invitro study. J Craniomaxillofac Surg 23:122, 1995

J Oral Maxillofac Surg 57:292-293, 1999

Discussion

Treatment of Mandibular Angle Fractures With a Malleable Noncompression Miniplate

H. Dexter Barber, DDS Private Practice, Philadelphia, PA; and Clinical Associate Professor of Oral and Maxillofacial Surgery, University of Medicine and Dentistry of NewJersey, Newark, NewJersey; e-mail: dexsurg@aol.com

The treatment of mandibular fractures has evolved over the years from wire fixation to rigid frxation.1-5 With both methods, when treated appropriately and with patient compliance, the outcome has been successful and resulted in proper bone healing. However, rigid fixation has been shown to provide a significant advantage in the treatment of mandible fractures, forming a “stronger bone” as well as requiring little or no maxillomandibular fixation (MMF), and thus allowing earlier physical rehabilitation and function for the patientG9 Rigid fixation as a treatment for mandibular fractures, specifically mandibular angle fractures, has also evolved and this article contributes to the evolution and efficacy of treatment modalities for mandibular angle frac- tures.

The authors evaluated a treatment concept for mandibu- lar angle fractures that used only a single malleable miniplate placed on the external oblique ridge from a transoral incision, without wire or elastic MMF postsurgery. This technique obviously differs from some previously accepted protocols for rigid fixation used for mandibular angle fractures. Classically, these protocols involved the elimina- tion of mobility of the fractured segments to allow for primary bone healing, achieving this immobility with bone plates and bicortical bone screws. My personal experience with the treatment of these types of fractures has primarily been with the use of the heavier 2.7 mm plates and the use of bicortical screws to allow for “rigid fixation.” However, I have used the technique presented by the authors on several occasions on patients whom I would consider extremely

compliant and have achieved good results, maintaining MMF with elastic for 2 weeks. This particular study did not use any MMF postoperatively and still obtained good results, but I am not sure whether the authors would consider their patients to be compliant.

The goal of treatment of all mandibular angle fractures is the restoration of proper occlusion and healing of the fracture site. This article supports the idea that this goal can be achieved in a more efficient manner because the surgery is a shorter procedure with less chance of nerve damage and a less expensive procedure because of less hardware, no MMF, and decreased operating room time (or performed in a clinic setting instead of an operating room), allowing the patient to return to normal function sooner.

The most interesting part of this study is how a plating system that you know is less rigid than other plating systems can lead to fracture healing and optimum clinical results and minimal complications with no MMF used postsurgically. Perhaps factors other than the rigidity or lack of rigidity of the Iixator may have influenced the results achieved with this study. One thought is that the small intraoral incision limits the amount of disruption of the periosteum resulting in improved vascular&y to the surgical site relative to traditional surgical approaches used with larger, more rigid plating techniques.8 Also, the technique that the authors used involves a relatively short procedure; thus, the perios- teum is exposed for a shorter period relative to using a more rigid plating system. Generally, there is less trauma and bleeding with shorter procedures and less complications such as an infection or a hematoma formation. Minimum disruption of the periosteum and improved vascularity enhance the opportunity for healing at the fracture site and decrease the chances of an infection or non-union to occur.3 With larger, more rigid plating systems, larger incisions are required and the potential exists for significant disruption of the periosteum.

Another factor that may have contributed to the fracture healing and minimal complications noted in this study is that when using bicortical screws there is inadequate cooling of