Functional outcomes following surgical treatment of bilateral mandibular condylar fractures

Abstract

Debate continues regarding unilateral or bilateral treatment for mandibular condylar fractures. This retrospective study evaluates the functional outcomes of bilateral condylar process fractures after surgical intervention. From May 1994 to December 2004, 51 adult patients with bilateral mandibular condylar process fractures were studied. There were 33 cases of bilateral condylar fractures (type I); 12 cases of condylar–subcondylar fractures (type II); and six cases of bilateral subcondylar fractures (type III). All patients underwent open reduction and internal fixation. Four patients had chin deviation, six had malocclusion, three had poor chewing function and eight had limited mouth opening. Type I patients had a significantly higher incidence of limited mouth opening ( P = 0.039) and associated maxillary fractures ( n = 12) and psychiatric disease ( n = 6) which yielded significantly poor functional outcomes. Complications included transient facial paresis ( n = 4), fracture and loosening of postoperative plates ( n = 3) and surgical wound infections ( n = 2). Open reduction with rigid fixation for bilateral condylar fractures provided satisfactory functional outcomes in this study. Concomitant maxillary fractures and underlying psychiatric problems are poor outcome factors. Aggressive rehabilitation in the first 9 months is important for early functional recovery.

Over the past 50 years, mandibular condylar fractures have caused significant management problems for maxillofacial surgeons. They are not uncommon after blunt facial trauma; the incidence is 25–51% . Many craniofacial surgeons favour open reduction and internal fixation (ORIF) to achieve satisfactory anatomical reduction, rapid fracture healing and early functional recovery . Some investigators have warned that complications such as osteoarthrosis, resorption and infection arise from the use of open reduction. Closed reduction accompanied by adequate physiotherapy yields acceptable results .

Regarding unilateral condylar process fractures in adults, many authors consider that conservative treatment with intermaxillary fixation (IMF) and physiotherapy could provide acceptable functional results, because of the present normal contralateral side. Ramus shortening with facial asymmetry is common after closed reduction, especially in subcondylar fracture . Significant improvement between the loss of preoperative and postoperative ramus height in open treatment was reported by V illarreal . Secondary orthognathic surgery might be required during long-term follow-up, if patients with condylar process fractures do not undergo ORIF . Serious sequelae, such as chin deviation (64%), trismus (17%) and incorrect condylar position (93%) are commonly following non-surgical treatment . There are few long-term results regarding bilateral condylar fractures in the literature . A study of 61 patients with bilateral condylar process fractures reported 28 mm of maximal mouth opening (MMO) in the group undergoing closed reduction and 44 mm in the open reduction group at 1 year of follow-up .

Classifications of condylar fractures have been proposed by M ac L ennan , L indahl and K renkel , but the correlations between different types of bilateral mandibular condylar process fractures, functional outcomes and complications were not specified . Most studies presented the results of condylar process fractures, which often mixed bilateral condylar fractures with unilateral condylar fracture. Rare studies analysed the outcomes of bilateral mandibular condylar process fractures . The purpose of this study is to reveal the surgical outcomes of bilateral condylar fractures after ORIF, according to the fractured level; it is a retrospective study so there are no non-surgical cases for comparison.

Materials and methods

Between May 1994 and December 2004, medical records from the Division of Trauma Plastic Surgery at Chang Gung Memorial Hospital for 79 consecutive patients with bilateral mandibular condylar process fractures were reviewed retrospectively. Condylar fractures in children ( n = 12) and bilateral condylar head comminuted fractures ( n = 8) precluding fixation of fracture fragments by hardware received closed treatment for condylar fractures. Fifty-nine patients received ORIF and eight patients with a follow-up record of less than 18 months were excluded. Fifty-one patients met the following study criteria: dentulous patients aged over 18 years; open reduction and internal rigid fixation performed for bilateral condylar displaced and/or dislocated fractures; and presentation of preoperative malocclusion.

Of the 51 patients, 30 were male and 21 were female. Mean age at time of injury was 28.8 years (range 18–68 years). Mean follow-up period was 18.5 months (range 18 months to 4 years). The difference between condylar head and subcondylar fractures in images and anatomy was clear and easily identified. The condylar neck bridge between the condylar head and subcondyle, was subject to fractures that often extended from the condylar head making it difficult to differentiate them from condylar head fractures. The authors regarded condylar head and neck fractures as the same category and classified these patients into three types ( Fig. 1 ): type I, bilateral condylar fractures (condylar neck or head); type II, one condylar plus one subcondylar fracture; and type III, bilateral subcondylar fractures. The definitions of condylar versus subcondylar fractures and displaced versus non-displaced fractures were based on L indahl and K renkel .

Fig. 1
Condylar process fractures according to fracture level. Type I: bilateral condylar fractures (above condylar neck). Type II: one condylar and the other subcondylar fractures. Type III: bilateral subcondylar fractures.

There were 33 type I patients, 12 type II patients and six type III patients. All patients presented preoperative malocclusion, included severe anterior open bite and cross bite. Preoperative image studies included computer tomography (CT) and panorex views to evaluate the location of the fractured site in different planes. Sixty-four of 66 fractured sites in type I, 23 of 24 in type II and all type III fractured sites were severely displaced and/or dislocated fractures. Twelve patients in the type I group and one patient in the type II group had associated maxillary fractures ( Table 1 ). Two type I patients and one type II patient with minimal displaced and/or dislocated condylar head fractures received closed reduction. ORIF was performed in severely displaced and/or dislocated fractures.

Table 1
The preoperative evaluation in malocclusion and fracture type.
Case Malocclusion * Maxillary fracture Displaced/dislocated fracture site Non-displaced/dislocated fracture site
Type I 33 33 12 64 2
Type II 12 12 1 23 1
Type III 6 6 0 12 0

* Malocclusion included severe anterior open bite and cross bite.

All surgical procedures were performed by the senior author (C.-T.C.). For condylar neck or head fractures, rigid fixation with one long screw (12–15 mm) for head fracture and miniplate or microplate for neck fracture via the preauricular approach was performed. Hardware was inserted through the same incision. The subcondylar fracture was fixed with miniplates through endoscope-assisted intraoral or retromandibular approaches. Distorted discs out of the glenoid fossa were reduced and repaired, if present. All concomitant mandible and maxilla fractures were treated by rigid miniplate osteosynthesis. All patients underwent postoperative IMF with elastic guidance for 1–2 weeks, followed by intensive physiotherapy, to maintain occlusion and resume early mouth opening.

The clinical examinations performed during regular follow-up included assessment of MMO, chin deviation, chewing function and status of occlusion. To determine whether a fair postoperative occlusion was achieved compared with pre-injury occlusion, the patient was evaluated by a senior plastic surgeon (C.-T.C.), orthodontists and self evaluated. MMO was measured preoperatively and 1, 3, 6, 9, 12 and 18 months after surgery. A shift of more than 5 mm of the mandibular midline at MMO was defined as chin deviation . Symptoms and signs such as joint pain, tightness and clicks were recorded as temporomandibular joint (TMJ) dysfunction. Postoperative images including CT and panorex views were taken to evaluate the degree of bone healing and related complications, such as implant failure or loosening, during regular follow-up.

Statistical analysis

The relationships between different variables were analysed using the nonparametric statistical test for non-normal variables. Univariate analysis (malocclusion, chin deviation, limitation of mouth opening, chewing function and TMJ symptoms and signs) was performed using Fisher’s exact test rather than the χ 2 test to categorize variables, because of the small number of type II and type III patients, as well as the large gap in the numbers in the three groups. An unpaired t -test was used to compare the limitation of mouth opening (mean ± SD) of the type I patients with and without underlying problems. The repeat-measurement test for continuous variables was performed in MMO, and is reported as mean ± SD. Differences were considered significant at P < 0.05.

Results

Patient distributions according to fracture type, age, gender, concomitant mandibular fractures, delayed operative time and mean follow-up time are shown in Table 2 . Of these 51 patients, 49 patients (96%) had concomitant mandibular fractures, of which mandibular symphysis and parasymphysis fractures were the most common. Thirteen patients (26%) had concomitant maxillary fractures; 12 were type I and one was type 2. Comparisons of the postoperative functional outcomes are reported in Table 3 . Mild anterior open bite (type I, 3/4; type II, 1/1; and type III, 1/1) was the most common complaint for five of six patients with malocclusion. Two type I patients and one type II patient developed mild anterior open bite, because of postoperative implant failures at the condylar neck level. Only one type I patient had mild posterior open bite. Four patients (8%) had chin deviation measured as chin point deviation (>5 mm) at MMO. The status of chewing function was based on the patients’ subjective feelings and the food ingested. Daily intake of a liquid diet only was deemed poor chewing function, a soft diet was fair, and a normal or hard diet was regarded as good chewing function. Two patients (4%) were limited to a soft diet and one patient (1%) could only ingest a liquid diet. No significant difference existed between the three fracture groups for outcomes of chin deviation, malocclusion status, and chewing function ( P > 0.05).

Table 2
Distribution of patients with bilateral mandibular condylar process fractures.
Age (mean years) Gender Associated mandibular fractures Psychiatric problems ** Mean delayed operation (days) Mean F/U (months)
Type I with M * ( n = 12) 27.6 M: 7
F: 5
12 4 5.2 19.4
Type I without M * ( n = 21) 29.1 M: 12
F: 9
20 2 5.9 21.1
Type II ( n = 12) 26.8 M: 7
F: 5
11 1 3.5 18.7
Type III ( n = 6) 29.7 M: 4
F: 2
6 0 2.7 19.2

* M: maxillary fracture.

** Psychiatric problems: schizophrenia and depression.

Table 3
Surgical functional outcomes of bilateral condylar process fractures.
Type I ( n = 33) Type II ( n = 12) Type III ( n = 6) Total P -value Type II + III ( n = 18) P -value
Chin deviation (>5 mm) 2 (6.1%) 1 (8.3%) 1 (16.7%) 4 (7.8%) 0.760 2 (11.1%) 0.641
Malocclusion 4 (12.1%) 1 (8.3%) 1 (16.7%) 6 (11.8%) 0.836 2 (11.1%) 1.000
Chewing function (score < 3) * 3 (9.1%) 0 0 3 (5.9%) 0.525 0 0.543
Trismus 8 (24.2%) 0 0 8 (15.7%) 0.159 0 0.039
Univariate analysis was performed by Fisher’s exact test for categorical variables.

* Chewing function score: hard diet (4), normal diet (3), soft diet (2) and liquid diet (1).

The limitation of mouth opening was defined as MMO measuring <35 mm at 1-year follow-up; only 8 type I patients (24%) had this problem ( Table 3 ). Significantly more instances of postoperative limitation of mouth opening were recorded in type I than that in type II and III patients ( P = 0.039). Correlations between different variables of MMO, regarding the postoperative time and fracture types were analysed using a repeat-measurement statistical test ( Table 4 ). The range of preoperative MMO distance was 7.5–24 mm for all patients. The type II group had better MMO recovery during the first 9 months of follow-up than the other two groups. At the 18-month follow-up, the average measured MMO was greater in the type III group than in the other groups, but the MMO differences between each type was not significant ( P = 0.065).

Table 4
Comparison of maximal month opening (mm) in three types.
MMO (mm) Pre-op
Mean ± SD
Post-op 1 month
Mean ± SD
Post-op 3 months
Mean ± SD
Post-op 6 months
Mean ± SD
Post-op 9 months
Mean ± SD
Post-op 1 year
Mean ± SD
Post-op 1.5 years
Mean ± SD
Type I 12.30 ± 0.90 18.70 ± 5.57 26.75 ± 0.90 32.03 ± 0.88 34.48 ± 1.14 35.83 ± 1.13 36.23 ± 1.14
Type II 12.41 ± 64 18.83 ± 3.66 28.33 ± 1.65 35.83 ± 1.60 38.25 ± 2.09 39.87 ± 2.06 40.12 ± 2.08
Type III 18.50 ± 2.31 17.67 ± 6.89 26.00 ± 2.33 32.33 ± 2.26 36.83 ± 2.95 40.68 ± 2.91 41.67 ± 2.94
Total 14.41 ± 0.99 18.62 ± 5.30 27.03 ± 0.99 33.40 ± 0.97 36.52 ± 1.26 38.29 ± 1.25 40.20 ± 1.26
Repeat-measurement test ( P -valve of Time × Group: 0.065).

Regarding the TMJ symptoms and signs, 102 condylar process fractures were recorded in 51 patients. The most common symptom was clicks (13/102 [13%]), followed by tightness (7/102 [7%]). Comparisons between the three groups are shown in Table 5 . Only one patient in type III complained of TMJ click and pain on the same side coincidentally. No statistical significance in the incidence of TMJ symptoms and signs was noted in the three types ( P > 0.05).

Table 5
Comparison of symptoms and signs of temporomandibular joints in three types.
Total numbers of condylar process fractures Clicks Tightness Pain
Type I (66) 10 (15.1%) 6 (9.1%) 4 (6.1%)
Type II (24) 2 (8.4%) 1 (4.2%) 1 (4.2%)
Type III (12) 1 (16.7%) 0 1 (16.7%)
Total (102) 13 (12.7%) 7 (6.9%) 6 (5.9%)
P -value 0.4495 0.6344 0.8277
Fisher’s exact test.

In this study, type I patients seemed to have less satisfactory results. To determine the key factors affecting outcome, further analysis was carried out in the type I group and a high incidence of maxillary fractures ( n = 12) was found ( Table 2 ). These patients were specifically analysed for functional comparison ( Table 6 ). Twelve patients in the type I group with maxillary fractures (Le Fort I, 8 and Le Fort II, 4) had significantly worse malocclusion outcomes (33%), chewing dysfunction (25%), limitation of mouth opening (58%) and symptoms and signs of TMJ (38%) comparing with non-maxillary fracture group ( P < 0.05). The non-maxillary fracture group in the type I patients at 1-year follow-up had significantly better MMO outcomes than those with maxillary fractures ( P = 0.014). Six type I patients with associated psychiatric problems (two with schizophrenia and four with depression) had poor mouth opening. The MMO at 1-year follow-up for the six type I patients with psychiatric problems (29.46 ± 8.02 mm) was far less than that for the other type I patients (39.84 ± 7.96 mm) (unpaired t -test; P = 0.007) ( Table 7 ). The functional investigations mentioned above could not be assessed accurately and objectively in the type I patients with psychiatric problems, so only MMO was evaluated for functional comparison.

Feb 7, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Functional outcomes following surgical treatment of bilateral mandibular condylar fractures
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