Infinitesimal Peri-angular Pterygomasseteric Transectioning Approach (IPPTA) for the Base Fractures of the Mandibular Condyle: A Preliminary Study

Abstract

Purpose

To investigate a reliable and safe surgical access to the condylar base region with minimal surgical trauma to the surrounding anatomic structures. In an attempt to do so, to describe Infinitesimal Peri-angular Pterygomasseteric Transectioning Approach (IPPTA) for the management of base fractures of the mandibular condyle.

Materials and Method

A preliminary clinical study involving 20 patients was undertaken to treat patients with unilateral condylar base fracture of the mandible using IPPTA under general anaesthesia (GA). Various parameters assessed were adequacy of surgical access, wound healing at the incision site, marginal mandibular nerve injury, diet intake and complications post-operatively.

Result

This method provided adequate exposure to fractured condylar base for open reduction and internal fixation (ORIF) with uneventful post-operative recovery phase. There was no limitation to function which was identified by restoration of normal pre-trauma diet intake by 14th post-operative day in more than 50% of the study patients. No complications were observed in any patients among the study population.

Discussion

The peri-angular approach has been discussed in the literature. The IPPTA highlights the use of a smaller incision providing an adequate exposure to the condylar base region for ORIF.

Introduction

The condyle is an anatomically weak point in mandibular skeleton which fractures readily when subjected to specific forces in order to disrupt transmission of these forces to the skull base. The reported incidence of fractures of the mandible involving condyle ranges from 20 to 35% [1, 2]. When indicated, open reduction with internal fixation (ORIF) for the treatment of condylar fractures is an established norm considering the superior outcome in terms of radiographic evidences of achievable anatomic reduction, post-operative improvement in quality of life with early recovery to function and overall functional outcome in the treatment of condylar fractures [3].

The complex surgical anatomy which remains a taboo for open joint surgeries in this region encourages surgeons to explore limited access surgeries in order to prevent surgical trauma to the vital structures and prevent or limit the incidence of anticipated complications [2]. With the availability of various classification systems clearly defining the anatomic disruption and displacement of joint structure [4, 5], it would be appropriate to device protocols for customising specific treatment for individual fracture type. In an attempt to have a safe surgical access to the condyle considering complex peri-condylar anatomy and have a predictable outcome, the minimal access surgery is proposed for base fractures of the mandibular condyle.

The objective of the present study is to describe an Infinitesimal Peri-angular Pterygomasseteric Transectioning Approach (IPPTA) for ORIF of base fractures involving mandibular condyle.

Patients and Methods

Study Design and Sample

The present study was carried out after obtaining an approval from the institutional ethical committee (IRB/RAC), IRB reference: OMS/TMJC/18/3045 and followed the Declaration of Helsinki on medical protocol and ethics. A prospective clinical study was designed involving 20 patients requiring surgery, ORIF under GA for unilateral base fracture of the mandibular condyle using Infinitesimal Peri-angular Pterygomasseteric Transectioning Approach (IPPTA). Patients participation in the present study was voluntary, and they were excluded if negative consent was given by them. They were allowed to withdraw from the study at any point without any negative consequences affecting their treatment. An informed consent was obtained from all the patients who were willing to participate in the study. A thorough clinical and radiographic examination was done during pre-surgical work-up (Figs. 1, 2). The incision placement followed by ORIF was performed by a single qualified operator for all the patients, and a research assistant assessed the post-operative parameters such as marginal mandibular nerve weakness, wound healing at the incision site, diet intake, requirement for maxilla-mandibular fixation (MMF) and complications, if any.

Fig. 1.

Orthopantomogram (OPG) of a patient with left base of the condyle fracture (as described in the Strasbourg Osteosynthesis Study Group Classification System)

Fig. 2.

Pre-operative postero-anterior (PA) view of skull radiograph depicting the presence of fracture in the left condylar base region requiring ORIF

The inclusion criteria were: (1) Patients aged between 18 and 55 years with unilateral base fracture of mandibular condyle in accordance with the Strasbourg Osteosynthesis Study Group (SORG) Classification [4] (Fig. 3); (2) ASA class I patients; (3) Patients willing to give written informed consent for the study. Exclusion criteria were: (1) Diacapitular and condylar neck fractures; (2) Condylar base fracture associated with concomitant other facial fracture involvement; (3) Non-compliant patients for the post-operative follow-up.

Fig. 3.

Prototype base fracture of mandibular condyle according to Strasbourg Osteosynthesis Study Group (SORG) where the fracture line runs behind the mandibular foramen and more than 50% below the perpendicular line through the sigmoid notch to the tangent of ramus (the inclusion criteria for the study)

Surgical Procedure

The surgical procedure was carried out following strict aseptic precautions by a qualified Oral and Maxillofacial Surgeon. GA was administered followed by securing the airway using naso-endotracheal intubation by an experienced anaesthesiologist trained for maxillofacial general anaesthesia procedures.

Technical Note

To perform the ORIF, minimal access modified Risdon type approach to the condylar base region via peri-angular incision was used. For hydro-dissection and local haemostasis, the surgical site was infiltrated with a local anaesthetic (LA) solution containing 2% lidocaine with 1:200000 epinephrine (Lox, Neon). The peri-angular incision was placed into the first cervical crease approximately 1.5 cm from the palpable bony angle (gonion) of the mandible. The length of the incision was limited within 1.5–2.0 cm following the curvature of the mandibular angle (deciding the length of the incision: skinny patients—1.5 cm, obese patients with bulky neck—2.0 cm). The vital anatomic landmarks that require identification during inward, superior and upward dissection of the planes include platysma, superficial layer of deep cervical fascia, masseter muscle, pterygomasseteric sling and tail of the parotid salivary gland. The palpable landmarks include gonion, anti-gonial notch, sub-mandibular salivary gland and anterior attachment of masseter at the lower mandibular border for orientation during surgical navigation. The aim of the surgical dissection was to reach the sub-masseteric plane by transectioning the pterygomasseteric sling between the tail of the parotid and anterior masseteric attachment to avoid facial vessels followed by stripping lateral ramal-masseteric fibre attachments along the posterior border of ramus to access condylar base region (Fig. 4).

Fig. 4.

Anatomy depicting the anatomic structures present in the vicinity of IPPTA access point for entering the sub-masseteric plane. Yellow dotted lines represent the marking for surgical entry to the mandibular bone

Following infiltration with LA solution, 1.5-cm-below and 1.5–2.0-cm-long peri-angular incision was placed after palpating the bony angle, posterior border of the ascending ramus in front of sternocleidomastoid and lower border of mandible. After placing the curvilinear incision perpendicular to the skin, sub-cutaneous fat tissue plane was visualised (Fig. 5). From this sub-cutaneous fat tissue plane, the dissection should be directed inward and superiorly with each surgical plane. After incising the sub-cutaneous tissue identified as yellowish fatty plane, platysma was identified (Fig. 6) and dissected carefully preserving the underlying cervical fascia of this region (Fig. 7).

Fig. 5.

Sub-cutaneous fat plane characterised by yellowish fat tissue beneath the skin after incision

Fig. 6.

Identification of the platysma muscle beneath the sub-cutaneous fat

Fig. 7.

Sub-platysmal fascia beneath the platysma muscle

The fascia was incised with close monitoring for any evidence of twitch in the lower lip or surrounding tissues, while using a fine point cautery tip as in this region marginal mandibular nerve is immediately above or adherent to the fascia. Once the fascial plane was incised, the pterygomasseteric sling (Fig. 8) was identified between the tail of the parotid posteriorly and anterior masseteric attachment at the lower border of mandible. The pterygomasseteric sling was transected preserving the parotid posteriorly and keeping transection short of anterior masseteric attachment at the lower border of mandible. After transecting the sling, dissection remains in the sub-masseteric plane, separating the muscular attachments from lateral and posterior ramal border superiorly, till condylar base was exposed. ORIF of the condylar base was performed using Titanium (Ti) miniplate and Ti screws (Fig. 9) along with achieving satisfactory occlusion assisted with intraoperative maxilla-mandibular fixation (MMF).

Fig. 8.

Identification of the angle with overlying pterygomasseteric sling between the posterior tail of parotid and anterior masseteric attachment at the inferior border of mandible

Fig. 9.

Access for reduction and fixation of the condylar base using titanium miniplate and screws

This approach gives an avascular field, without any major vessels in the course of dissection. Proper retraction and exposure provide an adequate field for condylar based reduction and fixation following principles of miniplate functional osteosynthesis (Fig. 10). After adequate reduction and fracture fixation, haemostasis was achieved and wound was irrigated with copious normal saline. The closure was done in layers re-approximating sling, fascia and platysma, sub-cutaneous layer and the skin. Appropriate pressure dressing using elastoplast/dynaplast (Johnson & Johnson elastic adhesive bandage) bandage up to 3rd post-operative day sufficed in almost all cases without any need for a surgical drain, when using this surgical incision. Injection cefotaxime 1 gm BD, diclofenac sodium 75 mg/1 ml (Aqueous) BD, metronidazole 500 mg/100 ml TDS, pantoprazole 40 mg OD was administered intravenously (IV) up to 3rd post-operative day followed by tablet cefixime 200 mg BD, diclofenac (50 mg)/acetaminophen (325 mg) combination BD and pantoprazole 40 OD per oral up to 7th post-operative day.

Fig. 10.

Post-operative postero-anterior (PA) view of skull radiograph depicting the presence of radiopaque material adherent to the condyle indicative of titanium implant used for anatomic fixation using IPPTA

Variables

The study variables outcome evaluation included assessment of the adequate surgical access, post-operative marginal mandibular nerve weakness, wound healing of the skin incision site, diet intake, requirement for maxilla-mandibular fixation using elastics (3/16″–3.5 Oz) and complications (if any).

Data Collection Methods

Data were collected by a single research assistant for all the patients. Marginal mandibular nerve weakness was assessed by visually observing symmetry and hypo-mobility of the lower lip. Wound healing on the incision site was assessed based on appearance (presence of slough/necrosis/hyper-granulation), colour of the incision edge and changes in sensation of the surrounding skin and presence of infection such as erythema/persistent localised pain/exudate/oedema. Diet intake was assessed using a ‘modified Likert scale’ published elsewhere [6]. All the patients were provided with the format containing the modified Likert scale, and the instructions were mentioned in the format as well as explained verbally. Requirement of MMF placement in the presence of unsatisfactory occlusion was performed as a chair side procedure post-operatively. The last clinical outcome evaluated was the presence of complications post-operatively, if any.

Results

A total of 20 patients (n = 20) participated in this study. Among 20 patients included in the study, n = 16 (80%) were males and n = 4 (20%) were females. Post-operative follow-up was done on 1st, 3rd, 7th day up to 3rd month. Visual evaluation to assess symmetry and hypo-mobility of the lower lip indicative of marginal mandibular nerve weakness showed mild drooping of the ipsilateral lower lip on smiling/blowing mouth in one patient, n = 1 (5%). Per oral administration of tablet wysalone (prednisolone) 40 mg for 3 days followed by gradual tapering from 4th day (up to seven days) was prescribed for the patient. Complete restoration of lip function and symmetry was noted at 2nd post-operative month. Patients n = 19 (95%) reported no abnormality in the nerve function in the immediate post-operative period.

All the patients n = 20 (100%) had satisfactory/uneventful wound healing at the skin incision site. There was absence of slough/necrosis, erythema, oedema, marginal contraction, at the site. 20% of the patients n = 4 required the placement of MMF using red (IMF) elastics to achieve satisfactory occlusion in the post-operative period which was removed after 3 weeks (Fig. 11). Diet intake was assessed using the modified Likert scale based on their ability to consume food. All the patients who underwent MMF reported delay in restoration of routine diet intake. Normal diet intake was restored on 3rd post-operative day in n = 3 (15%) patients, n = 4 (20%) on 7th post-op day, n = 5 (25%) on 14th post-op day, n = 3 (15%) on 21st post-op day, n = 2 (10%) on 31st post-op day, n = 1 (15%) each on 28th, 37th and 44th post-op day. Subsequently, all the patients were followed up every week up to 3rd month with uneventful outcomes in terms of form and function (Fig. 12).

Fig. 11.

Placement of maxillo-mandibular fixation (MMF) among the study patients in the post-operative period, n = 20

Fig. 12.

Restoration of normal diet intake among the study patients as assessed in the follow-up phase, up to 7th post-operative week. (Delay in diet restoration was observed in patient with MMF in the post-operative period)

None of the study patients n = 0 (0%) exhibited post-operative complications such as surgical site infection (SSI), sialocele formation, malocclusion. Though not a study parameter, no difficulty was noted in being restrained from performing daily activities among the study population in the post-operative period.

Discussion

There are several surgical approaches to the temporomandibular joint condyle [7–9]. Knepil et al. classified surgical approaches to condyle based on intended level of dissection to the plane of facial nerve as deep and traversing. Various types of incisions used to access the condyle were categorised into one of the above categories. Peri-angular incision also known as high sub-mandibular/modified high sub-mandibular approach or modified Risdon’s approach falls between buccal and marginal mandibular branch of facial nerve and is commonly used to approach condylar base fractures [9]. Kudva et al. proposed a modified peri-angular approach known as antero-parotid transmasseteric approach where they extended the dissection in the sub-platysmal plane between the anterior border of sternocleidomastoid and posterior border of sub-mandibular gland followed by dissection of superficial layer of deep cervical fascia anterior to parotid gland where the nerve was identified. Release of pterygomasseteric sling was avoided in this modified approach in contrast muscle dissection was undertaken in the vertical fashion. This approach enables the exposure of the entire condylar area except anterior to the parotid gland which may be difficult if the anterior process of the gland is highly developed causing accidental violation of the parotid gland, with complications including the transient facial nerve palsy or sialocele [10].

Oliveira et al. [11] evaluated the function of marginal mandibular nerve after surgical treatment of mandibular fractures by Risdon’s approach and observed mild dysfunction in 29.55% in the immediate post-operative period which gradually recovered in the late post-operative phase. Pau et al. [12] used modified high sub-mandibular approach for the management of condylar base fractures and found that high sub-mandibular approach does not violate the parotid gland thereby reducing complications, and transecting masseter creates a better surgical field exposing the condyle. Louvrier et al. [13] considered high sub-mandibular approach to be safe in managing patients with condylar base fracture. They found 2.2% transient facial nerve palsy among his study population.

In the present study, the approach was almost similar to the classic peri-angular approach but with a smaller curvilinear incision and dissection was along the direction of the nerve fibres minimising the possibility of damage. After placement of a curvilinear incision inferior and along the mandibular angle, followed by layered dissection, pterygomasseteric sling was transected in contrast to the technique advocated by Kudva A et al. The advantages of the proposed incision include appropriate condylar base exposure, avascular surgical plane, minimal access to the surgical site owing to the size of the incision and early functional recovery. We also recommend the use of this incision in obese patients where the anatomic landmark identification can pose difficulty. The limitation of this study remains a small group of study population, and validation of the observations would require multicentric larger similar surgeries.

The minimal access approach (IPPTA) was found inadequate for satisfactory surgical fixation of fractures as we ascend cranially to the neck region and the diacapitular fractures of the mandibular condyle considering the limited peri-angular incision length utilised for enhancing the margin of safety. In a single case attempted outside the context of the current study utilising IPPTA for condylar neck fixation, operators experienced limited surgical access to the neck region with difficulty in maintaining the perpendicularity for cranial end fixation (proximal screws). (Figure 13; Note the flushing of the screw heads with the screw aperture of the miniplate as we move cranially).

Fig. 13.

Fixation for fracture of the condylar neck done using minimal access peri-angular pterygomasseteric transectioning approach (IPPTA). Maintaining perpendicularity for cranial end fixation (proximal screws) is difficult using IPPTA incision depicted by flushing of the screw heads with the screw aperture of the miniplate as we move cranially

From this, we propose that IPPTA is safe and reliable for the treatment of patients with condylar base fracture requiring ORIF, with uneventful recovery post-operatively.

Funding

Nil.

Compliance with Ethical Standards

Conflict of interest

None.

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from the patients involved in this study (Study Number: OMS/TMJC/18/3045).