J Oral Maxillofac 46:362-366.

Surg

1990

Fixation of Mandibular

Fractures:

A Comparative Analysis of Rigid Internal Fixation and Standard Fixation Techniques THOMAS 6. DODSON, DMD, MPH,* DAVID H. PERROTT, DDS, MD,t LEONARD B. KABAN, DMD, MD,* AND NEWTON C. GORDON, DDS, MS5 This study used a prospective design to compare standard therapy (closed or open reduction with 4 weeks of maxillomandibular fixation) to rigid internal fixation (RF) for the treatment of mandibular fractures. Ninety-two patients with 143 fractures were evaluated and treated. There was no statistically significant difference in the treatment results between the two groups, despite a bias in the distribution of study variables that favored the standard therapy.

During the last 15 years rigid internal fixation (RIF) has become a commonly used technique for the treatment of mandibular fractures.’ RIF promotes primary bone healing without the extended use of maxillomandibular fixation (MMF) for immobilization. ‘.’ Eliminating MMF generally results in greater patient satisfaction because of decreased postoperative discomfort, earlier return to normal jaw function, easier maintenance of oral hygiene, and better nutrition. In addition, some studies have suggested that RIF results in a lower rate of infection, malunion, and nonunion when compared with standard treatment (open or closed reduction and MMF). ‘33-‘oDespite these advantages there are little data in the literature comparing the results of

Received from the University of California-San Francisco. * Assistant Clinical Professor, Department of Oral and Maxillofacial Surgery; Fellow, Dental Clinical Epidemiology Program, Department of Dental Public Health and Hygiene. t Assistant Professor. Department of Oral and Maxillofacial Surgery. $ Professor and Chairman, Department of Oral and Maxillofacial Surgery. 0 Clinical Professor, Department of Oral and Maxillofacial Surgery; Chief, Oral and Maxillofacial Surgery, San Francisco General Hospital. Supported in part by the Department of Oral and Maxillofacial Surgery Research Fund and the Dental Clinical Epidemiology Program. Department of Dental Public Health and Hygiene. Address correspondence and reprint requests to DrDodson: Department of Oral and Maxillofacial Surgery (S-738). University of California-San Francisco, 513 Pamassus Ave, Box 0440, San Francisco, CA 94143. 0 1990 American geons

Association

of Oral and Maxillofacial

0278-2391/90/4804-000553.00/o

Sur-

the standard technique with RIF in a prospective study.‘,7 The purpose of this study was to compare results and postoperative complications in a series of 92 patients with mandibular fractures treated by one of these two modalities. Methods We used a prospective, comparative study design with concurrent nonrandomized controls. The study sample consisted of patients with uninfected, isolated mandibular fractures who were admitted to the Oral and Maxillofacial Surgery Service at San Francisco General Hospital between July 1987 and September 1988. Eligible patients had no specific contraindication to either standard therapy or RIF. On admission, patients received either intravenous penicillin G, (l,OOO,OOOU every 6 hours), or clindamycin (600 mg every 6 hours, for penicillinallergic patients). Regardless of treatment choice, the patient was placed in MMF to establish the occlusal relationship. The control or standard therapy was defined as closed or open reduction with wire osteosynthesis and a 4-week course of MMF. RIF was defined as rigid fixation with compression plates or screws. The patients were placed in MMF for 2 days postoperatively for comfort. In patients treated with RIF who had associated subcondylar fractures, the period of MMF was extended up to 14 days. For RIF, the fracture was reduced using a bonereduction forceps and stabilized with a 4- to 6-hole Luhr (Howe-Medica, Rutherford, NJ) compression

363

DODSON ET AL

bone plate. The plates were carefully adapted to the cortex and were slightly overcontoured to permit lingual compression. Drains were used, when indicated, to prevent hematoma formation. In the standard treatment group, when open reduction was indicated, the fractures were stabilized with 24-gauge wire. Postoperatively, analgesics, intravenous fluids, and vitamin supplements were administered as indicated. Pa.tients received continuous IV antibiotic therapy during the hospitalization, and at discharge oral antibiotics were prescribed for a total course of 10 days from the time of admission. Patients were followed on a weekly basis in the oral and maxillofacial surgery clinic. The primary predictor variable was treatment modality, ie, standard therapy or RIF. The outcome variables were 1) successful fracture treatment defined as bony union, restoration of pretraumatic occlusion, and normal function; 2) postoperative weight change; 3) length of hospitalization; and 4) postoperative complications. Complications included infection, malunion, malocclusion, facial nerve injury, and noncompliance with treatment, ie, premature release of MMF by the patient. Because the study was nonrandomized, data collected on possible confounding variables included: age, sex, fracture etiology, type of fracture (simple or compound), number of fractures per patient, fracture location, dental status (dentate or edentulous), tooth status in line of fracture, medical history, time from injury to admission, time from admission to treatment, time from injury to treatment, and compliance with treatment. Other data collected were duration of follow-up, number of postoperative visits, and duration of MMF. Data were analyzed using the CSS version 2.1 from Statsoft (Statsoft Inc, Tulsa, OK), a statistical software program for the IBM-compatible personal computer. Continuous variables, such as age or length of hospitalization were analyzed using Student’s t test. Categorical variables, ie, sex or fracture type, were analyzed using contingency tables and computing a chi-square statistic. Multiple logistic regression was used to adjust for differences in the distribution of confounding variables between the two study groups. The logistic regression produces an estimate of the odds ratio. The odds ratio in this study was a measure of the association between treatment modality (RIF or MMF) and postoperative: complications. In a prospective study, it can be estimated by dividing the complication rate in the RIF group by the complication rate in the standard therapy group (RIF/standard therapy). An odds ratio of 1 suggests that there is no association between treatment modality and postoperative

complications. In this study, an odds ratio statistically greater than 1 would suggest that RIF was associated with an increased risk of postoperative complications (or alternatively, standard therapy had a decreased risk of complications). Conversely, an odds ratio statistically smaller than 1 would suggest that standard therapy was associated with an increased risk of postoperative complications (or RIF had a lower risk of postoperative complications). With 92 patients enrolled in this study, the odds ratio would have to be greater than 2.8 to be statistically different from 1. In other words, the complication rate in the RIF would have to be 2.8 times greater than the complication rate in the standard therapy group to be statistically significant. Results

The study sample consisted of 92 patients with a male-to-female ratio of 9.2:1. The mean age was 28.9 (SD + 9.1) years. Assault (85.9%) was the most common cause, followed by motor vehicle accidents (8.7%). Eighty patients (86.9%) had compound fractures, and 12 (13.1%) had simple fractures. A total of 143 fractures were treated. There were 24 subcondylar, 56 angle, 31 parasymphysis, and 32 mandibular body fractures. Patients were followed for an average of 43.5 + 2.1 days after discharge. Sixteen (17.4%) patients, however, were lost to follow-up within 1 week of discharge. Fifty-three patients (57.6%) received the standard treatment (closed reduction or open reduction with wire fixation) and 39 (42.4%) received RIF done from an extraoral approach. Patients in the RIF sample were older, had fewer simple fractures, and had more fractures per patient than those in the standard therapy group (P < .05 for all three variables). There was no statistically significant difference in the distribution of the remaining preoperative study variables (Table 1). Overall, 76 patients (82.6%; 30139 RIF, 46/53 MMF) had a successful result characterized by anatomic reduction, clinical union, restoration of pretraumatic occlusion, and normal function. During the postoperative period, there was no significant difference between the two study samples for the following variables: length of hospital stay, duration of follow-up after discharge, or number of postoperative visits. The average duration of MMF was 12.9 (210.6) days for the RIF group and 28.0 (? 14.5) days for the standard therapy group (P < .0003). Seven patients (13.2%) in the standard therapy group were noncompliant with MMF postoperatively. The average percent weight change (maximum decrease from admission body weight divided by admission body weight) was - 1.79% in the RTF

364 Table 1.

FIXATION OF MANDIBULAR

Descriptive Statistics

Study Variable Sample size Age* (yr) Sex Male Female Fracture etiology Assault MVA Other Not recorded Fracture type Simple Compound Fractures per patient* Dental status No tooth in fracture line Infected/injured tooth Impacted tooth Normal tooth Not recorded Medical history Positive Negative Interval from injury to treatment* (d)

Table 2. MMF Group

Value

39 31.6 2 11.0

53 26.9 2 6.8

,013

37 2

46 7

.39

34 2 2

45 6

1 1

-

.39

11 3s 1.72 -e .60

42 1.43 2 .60

Postoperative Findings

P

RIF Group

.028 ,017

FRACTURES

Study Variable Length of hospitalization* (d) Length of follow-up* (d) Duration of IMF* (d) Postoperative complications No Yes Infection Malunion Malocclusion Noncompliant Facial nerve palsy Weight change from admission weight* -

P

RIF Group

MMF Group

Value

4.92 f 1.91

4.14 t 2.24

,089

43.4 ? 36.7 12.9 k 10.6

43.6 2 33.9 28.0 _t 14.5

.97 .003

30 9 7 (17.9%) 0 (0%) 3 (7.7%) 0 (0%) 6 (15.4%)

46 7 6 (11.3%) I(1.9%1 1(1.9%1 7 (13.2%) 0 (0%)

.34

1.9% ‘- 4.1

-4.1

k 4.0

.55 .41 ,019

2 * Values are reported as mean t SD. 9 4 24 0

13 9 27 2

.697

14 25

13 40

.37

3.82 t 2.43

3.41 + 2.67

.45

* Values are reported as mean t_ SD.

group and - 4.10% for the standard therapy group (P = .019). Sixteen patients (17.4%) had postoperative complications. 9 patients (23.1%) in the RIF group and 7 patients (13.2%) in the standard therapy group (P = .34). The most common postoperative complication was infection (13/92, 14.1%). There were 7 infections in the RIF sample (17.9%) and 6 in the standard therapy sample (11.3%). In patients who were noncompliant with MMF, 2 of 7 (28.6%) had postoperative complications (P = .70). Other postoperative complications included malunion (I patient in the standard therapy group), malocclusion (3 patients in the RIF sample), and temporary facial nerve palsy (6 patients in the RIF sample) (Table 2). The odds ratio estimate of the risk of postoperative complications for RIF relative to standard therapy was 1.97 (P = .34). After adjusting for differences between the distribution of potential confounding variables in the two study samples (ie, age, number of fractures per patient, and fracture complexity, and for the time when each patient entered the study), the odds ratio decreased to 1.Ol (P = .97). Given that the odds ratio was not statistically different from 1, this suggests that there was no significant difference in the postoperative com-

plication rates between the two treatment ties.

modali-

Discussion

In this series, 76 of 92 (82.6%) patients had a clinically successful outcome defined as bony union and restoration of occlusion and function. There was no significant difference in the postoperative complication rates between standard therapy and RIF; however, the types of complications in the two groups were different. Patients with RIF had a higher frequency of malocclusion and transient facial nerve palsy (see Table 2). These complications were probably secondary to technical errors that occurred early in the study. For example, some patients were placed in MMF with Ivy loops rather than arch bars. In such cases, lack of rigidity in the fixation permitted torsion on the fracture segments as the compression screws were tightened. Displacement of the superior aspect of the fracture was especially significant if the plate was not perfectly adapted to the mandible. Another common error was to use an incision that was too small to permit placement of the bone plates without considerable retraction of soft tissue. Consequently, several patients developed a traction injury of the facial nerve (marginal mandibular branch) and had temporary postoperative palsy. In all cases the nerve function was recovered within 3 months. In the standard therapy sample, there was a higher frequency of noncompliance with the prescribed duration of MMF than in the RIF sample. Two of the seven patients who prematurely re-

365

DODSON ET AL

leased their MMF developed postoperative complications. RIF is technically demanding. Our group experienced the sharp “learning curve” described in previous reports. 3*” During the first 6 months of the study, the postoperative complication rate in the RIF sample was 36.8% (709). During the next 9 months, the complication rate decreased to 10% (2/ 20). The majority of complications may be directly due to failures in technique. In a current study, we are tracking complications to document a more accurate complication rate inherently determined by the method rather than by the method and operator inexperience. Clearly, study variables were not equally distributed between the two groups (Table 1). The RIF group was older, had fewer simple fractures, and had more fractures per patient than the standard therapy group. These factors may bias the study in favor of the standard therapy group. Despite this bias, there was no statistically significant difference in postoperative complication rates (Table 2). After adjusting for these potential confounding variables and the time when the patient entered the study, the odds ratio decreased from 1.97 to 1.Ol , thus minimizing the initial difference between the two study groups. Theriot et al3 published the only randomized clinical trial in the literature evaluating the treatment of mandibular fractures. The study sample was limited to patients who required open reduction. They were then randomized to receive MMF or RIF. These investigators also failed to detect a statistically significant difference in the postoperative complication rate between RIF (4.9%) and MMF (11.3%). Two possible conclusions can be drawn from the fact that no significant difference was detected between the two types of treatment under investigation: 1) there is truly no difference between the two treatment modalities, or 2) the investigators failed to detect a difference because of an inadequate sample size. Statistical power measures the probability that a specified statistically significant difference would be detected given the available sample size. A generally accepted minima1 level of power in a study is 80%. ‘L’~ Based on the sample sizes, the power to detect a difference was 20% for Theriot et al3 and 25% for the current study. In other words, based on a sample size of 92 patients, we had a 25% chance of detecting a statistically significant result between treatment modalities if the difference was 210%. It would have required approximately 200 patients in each treatment group (400 patients total) to achieve a power of 80% with the complication rates of 23% for RIF and 13% for standard therapy found in this study.

Although the two treatment modalities may be equivalent regarding treatment outcome and complications, RIF offers marked advantages for transient or indigent patient populations. Almost 25% of the patients in this study were either noncompliant with MMF or were lost to follow-up within 1 week of discharge. Noncompliant patients who released their MMF had the highest complication rate in this study (28.5%). In contrast, the RIF technique does not require significant postoperative patient cooperation or supervision. RIF patients who are noncompliant may have a lower risk of developing malunion, nonunion, or infection than noncompliant patients in the standard therapy group. Even if a study with 400 patients would have detected a 10% difference in complication rates between the two groups, RIF still offers significant advantages over standard therapy in certain clinical settings. It may be particularly appropriate in the care of noncompliant patients, patients who require early mobilization or access to the oral cavity (ICU patients), and patients with special nutritional requirements such as diabetics, alcoholics, those with infected fractures who require an open reduction, those with seizure disorders, or those who would benefit from avoiding extended periods of MMF because of their occupation (ie, teachers, lawyers, or sa1espersons).3,4*‘4*‘5 In the future, comparisons of standard therapy and RIF should use a randomized study design, and all patients with isolated mandibular fractures should be eligible for enrollment. Randomization will help to produce two study groups that are comparable in terms of both known and unknown risk factors. These studies should also enroll enough patients to have adequate power to detect a prespecified difference between the two treatment modalities. In the current era of increasing medical costs, a cost-effectiveness analysis of the two treatments would be helpful. Bone plates and screws are more expensive than wire, and in general, the operation using RIF is more time consuming than standard therapy. Because of the cost differences, there is an obligation to perform a randomized clinical trial to document the potential clinical and economic advantages of one method over the other. References I. Spies4 B: Internal Fixation of the Mandible. New York, NY, Springer Verlag, 1989, pp vii, 15-16 2. Jones JK, Van Sickels JE: Rigid Fixation: A review of concepts and treatment of fractures. Oral Surg Oral Med Oral Path01 65:13, 1988 3. Theriot BA, Van Sickels JE, Triplett RG, et al: Intraosseous

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4.

5.

6. 7. 8.

9.

wire fixation versus rigid osseous fixation of the mandible: A preliminary report. J Oral Maxillofac Surg 45577, 1987 Tu HK, Tenhulzen D: Compression osteosynthesis of mandibular fractures: A retrospective study. J Oral Maxillofac Surg 43:585, 1985 Ewers R, Harle F: Experimental and clinical results of new advances in the treatment of facial trauma. J Plast Reconstr Surg 75:25, 1985 Klotch DW, Bilger JR: Plate fixation for open mandibular fractures. Laryngoscope 95: 1374. 1985 Cawood JI: Small plate osteosynthesis of mandibular fractures. Br J Oral Surg 23:77, 1985 Champy M, Lodde JP, Schmidtt R. et al: Mandibular osteosynthesis by miniature screwed plates via a buccal approach. J Maxillofac Surg 6:14, 1978 Luhr HG: Compression plate osteosynthesis through the Luhr system, in Kruger E, Schilli W (eds): Oral and Max-

FIXATlON OF MANDIBULAR

FRACTURES

illofacial Traumatology. Chicago, IL, Quintessence, 1982. pp 319-348 IO. Strelzow VV. Strelzow AG: Osteosynthesis of mandibular fractures in the angle region. Arch Otolaryngol 109403. 1983 11. Frost DE, El-Atter M, Moos KF: Evaluation of metacarpal bone plates in the mandibular fracture. Br J Oral Surg 21:214, 1983 12. Friedman LM, Furberg CD, DeMets DL: Fundamentals of Clinical Trials. Littleton. MA, PSG, 1985. p 92 13. Hulley SB, Cummings SR. Browner WS. et-al: Designing Clinical Research. Baltimore. MD. Williams & Wilkins. 1988. p 133 14. Adell R, Ericsson B, Nyleno 0, et al: Delayed healing of fractures of the mandibular body. Int J Oral Maxillofac Surg 16:15, 1987 15. Johansson B, Krekmanov L, Thomsson M: Miniplate osteosynthesis of infected mandibular fractures. J Craniomaxillofac Surg 16:22, 1988