Superior border versus inferior border fixation in displaced mandibular angle fractures: prospective randomized comparative study

Abstract

A prospective randomized comparative study was conducted to compare open reduction and internal fixation of displaced fractures (>2 mm) via intraoral approach with application of a single monocortical miniplate according to Champy’s ideal line of osteosynthesis (group A) versus an extraoral approach with application of an inferior border plate with at least two holes (bicortical screws) on either side of the fracture line (group B). Clinical and radiographic assessment was done preoperatively, immediately postoperative, and at 1, 4, and 12 weeks of follow-up. Parametric and non-parametric data were evaluated by independent samples t -test and χ 2 analysis, respectively; P < 0.05 was considered statistically significant. There was no significant difference between the two groups with regard to complication rates, although functional outcomes including pain (visual analogue scale score) at the 1-week follow-up and inter-incisal mouth opening at the 12-week follow-up were found to be better in group B. On radiographic assessment, the inferior border was better aligned in group B than in group A, with no superior border distraction in group B. The duration of surgery was shorter in group B, and this was considered to be the easier approach for fixation of the device as assessed by the surgeons.

Amongst mandibular fractures, mandibular angle fractures represent the largest percentage. Angle fractures are plagued by more complications than other mandibular fractures, the incidence ranging from 0% to 32%. The angle fracture is the subject of various controversies, second only to condylar fractures.

Various treatment modalities have been advocated, but no consensus has been reached as yet. The traditional biomechanical model comprising tension at the superior border and compression at the inferior border has been challenged, and it has been found that these tension compression zones reverse as the load position moves posteriorly.

The aim of this prospective study was to compare open reduction and internal fixation (ORIF) of displaced fractures (>2 mm) via an intraoral approach with application of a single monocortical miniplate according to Champy’s ideal line of osteosynthesis (categorized as group A) versus ORIF via an extraoral approach with application of an inferior border plate with at least two holes (bicortical) on either side of the fracture line (categorized as group B).

Patients and methods

All patients with an angle fracture of the mandible treated in the department of oral and maxillofacial surgery between February 2011 and June 2012 (17 months) were offered participation in this prospective study. They were informed of the need to attend 3 months of follow-up. The patients were required to provide informed consent or to refuse participation in the study. Patient information was documented on a consent form. Patients were fully informed of the possible advantages and disadvantages of both treatment options. Titanium miniplates of the same size and from the same manufacturer were used in both study groups. To ensure randomization and avoid any bias, the selection of one of the two treatment modalities was done by a computer-randomized draw of lots for all of these patients. The design and method of randomization was approved by the institutional ethics committee before the study was started.

The inclusion criterion was an angle fracture of the mandible (according to the Association for Osteosynthesis (AO) classification). The criteria for exclusion were as follows: infected fractures, comminuted fractures, age <16 years, and edentulous patients.

An adequate number of cases, irrespective of sex, caste, religion, and socioeconomic status, were selected. Patients were established to have a displaced fracture on the basis of displacement of the inferior alveolar canal, as assessed on panoramic radiograph (>2 mm).

Assessment of treatment variables and clinical parameters

Patients were assessed preoperatively, postoperatively, and at 1 week, 4 weeks, and 12 weeks of follow-up.

Treatment variables assessed were: time interval between the injury and surgical treatment; duration of surgery from incision to the last suture; and surgeon’s assessment of the ease of application of the fixation device(s), registered as ‘simple’, ‘some difficulty’, or ‘very difficult’.

Clinical parameters assessed were: pain (on a visual analogue scale (VAS), with a value from 0 (no pain) to 10 (strongest pain or discomfort)); neurosensory dysfunction (none, hypoaesthesia, anaesthesia, dysaesthesia); inter-incisal dimension (mm) at last follow-up; occlusion (registered as satisfactory or unsatisfactory); wound problems, including cellulitis, purulence, dehiscence of the incision, plate exposure, granulation tissue at incision, objectionable scarring (yes/no); facial nerve paresis (yes/no); and clinical union at last follow-up visit (yes/no).

These observations were recorded by two oral and maxillofacial surgery residents who were not involved in the treatment planning or subsequent operative procedures; they were thus blinded to the treatment the patient had received.

Radiographic assessment

The accuracy of fracture reduction and the stability of fixation were assessed on the basis of radiographs obtained preoperatively, immediately postoperative, and at 1 week, 4 weeks, and 12 weeks postoperatively.

Preoperative radiographic images (posterior–anterior view of the mandible, panoramic radiograph) were used to assess the location of fractures and the amount of displacement. Displacement of the inferior alveolar canal was assessed on panoramic radiograph and the fracture was categorized as displaced when displacement of the canal was >2 mm ( Fig. 1 ).

Fig. 1
Assessment of displacement on panoramic radiograph.

Postoperative radiographic images (posterior–anterior view of the mandible, panoramic radiograph) were used to assess the adequacy of fracture reduction. Reduction was also assessed on the basis of realignment of the inferior alveolar canal.

Treatment

All patients were operated on under general anaesthesia or conscious sedation. The patients in group A were treated with ORIF via an intraoral approach, in which a single monocortical miniplate was applied according to Champy’s ideal line of osteosynthesis. A 4-hole non-compression titanium miniplate was adapted along the medial side of the external oblique ridge (adaptation in two planes) after curving the plate, and was screwed to the bone using 2.0-mm self-threading screws. No transbuccal trocar was necessary for instrumentation.

The patients in group B were treated with ORIF via an extraoral approach using a standard submandibular incision, in which an inferior border plate (4-hole 2.0-mm non-compression titanium miniplate, bicortical screws) with at least two holes on either side of the fracture line was fixed. Minimal soft tissue detachment was done, limited to the inferior border and lateral surface of the angle fracture and sufficient for appropriate plate positioning and reduction.

Postsurgical intermaxillary fixation (IMF) with the use of upper and lower arch bars with elastics/wires was used for 3–5 days in all patients. A pressure bandage was applied on the lateral aspect of the angle in all patients, as this was contributory in minimizing postoperative haematoma/oedema. All patients were given a 3-day course of systemic antibiotics and instructions on oral hygiene, including the use of chlorhexidine mouth rinse for 2 weeks. All patients were kept on a soft/liquid diet.

Three months of follow-up data were recorded in this study. The results were entered on a specific form. Parametric data were evaluated with an independent samples t -test. Non-parametric data were analyzed by χ 2 analysis. A P -value of less than 0.05 was considered statistically significant.

Results

A summary of the results and the statistical analysis is presented in Tables 1 and 2 .

Table 1
Summary of the results and statistical analysis.
Variable Group A (intraoral) n = 20 Group B (extraoral) n = 20 P -value
Time interval between injury and surgical treatment, mean ± SD 5 ± 2.6 days 4.4 ± 3.2 days 0.264
Duration of surgery, mean ± SD 45.25 ± 4.44 min 31.80 ± 4.42 min 0.000 *
Surgeon’s assessment of the ease of application of the device ‘Simple’ = 60% ( n = 12) ‘Simple’ = 90% ( n = 18) 0.028 *
‘Some difficulty’ = 40% ( n = 8) ‘Some difficulty’ = 10% ( n = 2)
Occlusal discrepancy 10% ( n = 2) 5% ( n = 1) 0.548
Wound problems 10% ( n = 2) 5% ( n = 1) 0.548
Facial nerve paresis 0 5% ( n = 1) 0.311
Clinical union 100% 100%
Radiographic assessment: gap/distraction 4 0 0.035 *
SD, standard deviation.

* Statistically significant difference.

Could not be determined statistically because the standard deviation of both groups was zero. No practical difference existed.

Table 2
Summary of the results and statistical analysis clinical parameters.
Variable Pain (VAS) Neurosensory deficit Inter-incisal dimension
Group A (intraoral) n = 20, mean ± SD Group B (extraoral) n = 20, mean ± SD P -value Group A (intraoral), number of patients Group B (extraoral), number of patients P -value Group A (intraoral) Group B (extraoral) P -value
Preoperative 7.15 ± 1.50 6.85 ± 1.27 0.498 5 10 0.102 14 14.7 0.547
Postoperative 5.45 ± 2.19 4.35 ± 1.81 0.092 7 9 0.519 IMF IMF
1-week follow-up 3.30 ± 1.72 2.10 ± 1.45 0.022 * 6 8 0.507 18.3684 20.95 0.056
4-week follow-up 1.45 ± 1.32 0.60 ± 1.43 0.058 2 2 1.000 25.6 26.7 0.435
12-week follow-up 0 0 NS 1 1 1.000 32.25 37.45 0.013 *
VAS, visual analogue scale; SD, standard deviation; IMF, intermaxillary fixation; NS, not significant.

* Statistically significant difference.

Demographic results

In the present study, mean age at the time of injury was 27.35 years. Among 40 patients, 38 were male and two were female, giving a male to female ratio of 19:1. The most common cause of injury was found to be roadside accident (52.5%), followed by assault (37.5%) and fall (10%).

There was no statistically significant difference between the two groups with regard to age at the time of injury, gender, or cause of the injury. Thus, two identical populations were identified for the injuries sustained. Thirteen out of 40 (32.5%) patients were smokers.

Treatment variables

Time interval between injury and surgical treatment

Group A (intraoral) patients received surgical treatment within a mean duration of 5 days (range 1–10 days, standard deviation (SD) 2.6 days). Group B (extraoral) patients received surgical treatment within a mean duration of 4.4 days (range 1–15 days, SD 3.2 days). There was no statistically significant difference between the groups in terms of the time interval between injury and surgical treatment ( χ 2 = 2.667, df = 2, P = 0.264).

Duration of surgery

The duration of surgery in group A (intraoral) ranged from 40 to 55 min, with a mean of 45.25 min (SD 4.44 min). In group B (extraoral), the duration ranged from 25 to 40 min, with a mean of 31.80 min (SD 4.42 min). There was a statistically significant difference between the two groups in terms of the duration of surgery ( t = 9.606, df = 38, P = 0.000).

Surgeon’s assessment of the ease of application of the device

For group A (intraoral), 60% ( n = 12) of the surgeons rated the plate application to be ‘simple’, while 40% ( n = 8) rated it as ‘some difficulty’. None of the surgeons found it to be ‘very difficult’. In group B (extraoral), 90% ( n = 18) of the surgeons rated the plate application as ‘simple’, while 10% ( n = 2) rated it as ‘some difficulty’. None of the surgeons found it to be ‘very difficult’. There was a statistically significant difference between the two groups in terms of the surgeon’s assessment of the ease of application of the device ( χ 2 = 4.801, df = 1, P = 0.028).

Clinical parameters

Pain (VAS)

There was no statistically significant difference between the two groups with regard to the pain VAS scores, except for the scores at the 1-week follow-up. VAS scores at 1-week follow-up were lower in group B (extraoral) (2.10 ± 1.45) than in group A (intraoral) (3.30 ± 1.72); the difference was statistically significant ( t = 2.387, df = 38, P = 0.022).

Neurosensory dysfunction

In group A (intraoral), 25% of patients ( n = 5) had a post-injury/presurgical neurosensory deficit, while in group B (extraoral), 50% of patients ( n = 10) had a post-injury/presurgical neurosensory deficit. In only one patient in each group was the deficit unresolved at the 3-month follow-up.

Three patients (15%) in group A (intraoral) had no post-injury/presurgical paraesthesia but developed this postsurgery. No such finding was noted in group B (extraoral).

There was no statistically significant difference between the two groups in terms of neurosensory deficit preoperatively, immediately postoperative, or at 1 week, 4 weeks, or 12 weeks of follow-up.

Inter-incisal dimension

With regard to the inter-incisal dimension, there was no statistically significant difference between the two groups through 4 weeks of follow-up. At the 12-week follow-up, mouth opening was greater in group B (extraoral) (37.45 ± 7.6) as compared to group A (intraoral) (32.25 ± 4.7); this difference was statistically significant ( t = 2.606, df = 38; P = 0.013).

Occlusion

In group A (intraoral), preoperative occlusion was deranged in 95% of cases ( n = 19). During the follow-up period, two patients ( n = 10%) were found to have developed an occlusal discrepancy at the 1-week follow-up. The discrepancy was resolved in one patient by minor occlusal grinding; in the other patient the discrepancy eventually resolved following continuation of IMF for another week.

In group B (extraoral), preoperative occlusion was deranged in 100% of cases ( n = 20). During the follow-up period, one patient ( n = 5%) was found to have developed an occlusal discrepancy at the 1-week follow-up, which was resolved by minor occlusal grinding.

There was no statistically significant difference between the two groups in terms of occlusal discrepancy ( χ 2 = 0.360, df = 1, P = 0.548).

Wound problems

Two patients in group A (intraoral) (10%) had wound dehiscence with an infection, which subsided with local wound care and antibiotics. One of these patients ultimately had to undergo a second surgery for plate removal. In group B (extraoral), one patient (5%) had an infection with a suppurative discharge, which resolved with local drainage and antibiotics. There was no statistically significant difference between the two groups in terms of wound problems ( χ 2 = 0.360, df = 1, P = 0.548).

Facial nerve paresis

One patient in group B (extraoral) (5%) had facial nerve paresis, while in group A (intraoral), no patient suffered this complication. The affected patient had recovered by the fourth month, after exercise therapy. There was no statistically significant difference between the two groups in terms of facial nerve paresis ( χ 2 = 1.026, df = 1, P = 0.311).

Clinical union

None of the patients in group A (intraoral) or group B (extraoral) suffered non-union or malunion; all had complete clinical union.

Radiographic assessment

On radiographic assessment of the postoperative radiographs, adequate anatomic reduction was found in group B (extraoral) with no distraction of the superior border and good lower border alignment. In group A (intraoral) there were four patients in whom a gap was visualized on the radiographs at the lower border ( Figs. 2–5 ). The difference was statistically significant ( χ 2 = 4.444, df = 1, P = 0.035), indicating better fracture alignment in group B (extraoral) cases.

Jan 19, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Superior border versus inferior border fixation in displaced mandibular angle fractures: prospective randomized comparative study
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