Functional changes following distraction osteogenesis treatment of asymmetric mandibular growth deviation in unilateral juvenile idiopathic arthritis: a prospective study with long-term follow-up

Abstract

In juvenile idiopathic arthritis (JIA), temporomandibular joint involvement is a frequent complication leading to deficient mandibular growth. Occurring unilaterally this will give rise to mandibular and maxillary asymmetry that will affect the soft tissue and the muscles and result in complex dentofacial anomaly. In the case of severe dentofacial malformation, orthognathic surgery is the only treatment option. Vertical osseodistraction of the mandibular ramus has been suggested as a means of rectifying the mandibular growth deviation and soft-tissue problems. Whether such treatment introduces dysfunctional side effects of the temporomandibular joint and muscles has been debated and concern has been raised that treatment impairs the patient’s mouth opening capacity and mandibular movement. The present study prospectively evaluated 23 patients with JIA and mandibular asymmetry caused by unilateral temporomandibular joint arthritis. The authors found a clinical effect on the asymmetry with only minor subjective complaints and limited objective changes in functional parameters.

Juvenile idiopathic arthritis (JIA) is a chronic disease characterized by inflammation of the synovial tissue in the joints of children before they reach the age of 16 years. Diagnostic criteria are described by the International League of Associations for Rheumatology (ILAR). In Denmark, the incidence of JIA is 15/100,000 per year and the prevalence of children with JIA is approximately 1000 in the Danish population of 5.5 million inhabitants.

The temporomandibular joint (TMJ) is frequently involved and inflammation can be revealed by magnetic resonance imaging (MRI); the prevalence of this condition is 75–87%. The condition may give rise to mandibular and lower face growth disturbances in the form of a retrognathic mandible with a short posterior face height resulting in an open bite. Maxillary compensation will develop and lead to a steep occlusal plane. Occurring unilaterally it often causes mandibular asymmetry and reduced growth causes a transverse inclination of the occlusal plane and lower border as seen from the frontal perspective.

The developing asymmetry can be treated, for example with an orthopaedic functional appliance, which may treat the TMJ symptoms as well. In a number of patients, however, the resulting jaw deformity is so pronounced that surgical intervention is required. Surgical treatment strategies have included costochondral graft reconstruction, total TMJ prosthesis and conventional orthognathic surgery.

The use of osseodistraction for correction of mandibular deformity caused by JIA has been described in a few publications, which were all case reports. A comprehensive meta-analysis of mandibular osseodistraction in 539 patients included 14 JIA patients with unilateral osseodistraction (2.6%). In growing patients, distraction osteogenesis (DO) can be combined with orthopaedic appliances to control further growth.

The conventional surgical strategy for treatment of mandibular asymmetry is to perform orthognathic surgery after growth has ended. The procedure always includes bilateral mandibular osteotomy and usually maxillary osteotomy as well. Severe asymmetry is a therapeutic challenge and outcomes are often not optimal. This has encouraged the authors to develop their current treatment strategy in which they aim to correct asymmetry by DO during adolescence and subsequent, appropriate orthopaedic/orthodontic treatment. At the authors’ institution, all children with JIA are referred for an evaluation of their TMJs. If they have any clinical signs of arthritis or growth deviations, they are initially treated with occlusal splints to curb the effect of TMJ arthritis on their mandibular growth and dentoalveolar development. All are closely monitored with collection of anamnestic and clinical data throughout their growth period. If growth is severely impaired, the option of DO is presented. The principal concerns regarding DO treatment of JIA patients are the uncertainty of the extent of the negative functional effects of distraction and the permanency of the treatment result which, if not permanent, may give rise to further TMJ changes. The aim of the present prospective study is to present the results in terms of functional symptoms and clinical findings of unilateral internal mandibular DO in 23 asymmetric patients with JIA presenting with unilateral arthritis in the TMJ.

Materials and methods

From 1998 to 2009, 23 patients with JIA diagnosed according to the ILAR criteria underwent unilateral DO at the Department of Oral and Maxillofacial Surgery, Aarhus University Hospital ( Table 1 ).

Table 1
Patient data and treatment variables.
No. of patients Mean Standard deviation
Gender (M/F) 9/14
Age at onset (years) 6.4 3.9
Medication
MTX 4
NSAID 6
SAL 1
No 12
Age at surgery (years) 15.8 4.7
Side of surgery
Left 9
Right 14
Removal third molar
Yes 17
No 6
Latency period (days) 3.8 1.0
Rate (mm/day) 1.1 0.2
Total distraction, R side (mm) 17.9 2.0
Total distraction, L side (mm) 18.6 1.8
Consolidation period (days) 66 11
Surgery at device removal
Le Fort I 7
Genioplasty 1
Later surgery
Le Fort I 2
Genioplasty 1

TX, methotrexate; NSAID, non-steroidal anti-inflammatory drug; SAL, salazopyrin.

Inclusion criteria were: JIA diagnosis; unilateral TMJ involvement; clinically and radiologically verified facial asymmetry related to unilateral short ramus development; and inactive disease with or without medication. Of the patients, 11 had persistent oligoarticular JIA, four had extended oligoarticular JIA, four had rheumatoid factor-negative polyarticular JIA, one had psoriatic JIA, one had enthesitis-related arthritis and two had undifferentiated subtype JIA. Twenty patients were treated with orthopaedic appliances. If their growth restriction produced marked asymmetry, they were referred for orthognathic surgery planning. Three patients were fully grown at the time surgery was decided.

All patients were treated according to a standardized protocol developed at the Department of Maxillofacial Surgery, Aarhus University Hospital and the Department of Orthodontics, Aarhus University. The protocol implied preoperative orthodontic treatment, cephalometric analysis with calculation of distraction vector and transfer of vector to the surgery. Evaluation of TMJ stability was based on repeated clinical observations. Inactive disease was evaluated by a specialist in paediatric rheumatology and assessment of TMJ inactivity was done by an orthodontist with specific training in TMJ involvement in JIA patients. The criterion for proceeding with the corrective surgery was a TMJ with clinical and subjective good function. If there was any active disease of the TMJ at this evaluation DO was precluded. Radiological examination with panoramic X-ray or cone beam computed tomography (CBCT) demonstrated sufficient height and bone quality to assume that the function of the joint could be preserved. Eleven patients were treated for joint involvement in joints other than the TMJ.

The patients treated with methotrexate had the drug discontinued 1 week before and 2 weeks after surgery. No patients had any surgery to the TMJ before the DO and none of the patients had steroid injections of their TMJ. MRI and CT were not performed routinely.

Additional surgery was performed at the time of removal of the distraction device in eight patients (35%): seven Le Fort I, one genioplasty; and later in three patients (13%) two Le Fort I and one genioplasty. DO was the only treatment in 12 patients (52%).

The authors prospectively examined the patients for subjective symptoms, dentofacial morphology, TMJ function and occlusion. Data from four examinations were included in this study: T1, before DO, T2, after removal of the distraction device, T3, 6 months after DO, and T4, long-term follow-up (1–6 years). Patients were interviewed about the following symptoms: swelling of the TMJ, clicking, crepitation and locking of the TMJ with mandibular movement, TMJ pain, morning stiffness, muscular soreness, headache, chewing disability and mouth opening ability.

The clinical examination included: morphological dentofacial characteristics such as soft tissue function, TMJ swelling, TMJ tenderness on palpation, TMJ clicking, translation of the condylar head, crepitation of the joint, tenderness on palpation of chewing muscles, characteristics of the dental status and occlusion, mouth opening capacity, range of laterotrusion and protrusion. A clinical examination including the latter characteristics was carried out by the same examiner throughout the study.

Movements of the jaw were considered to be decreased if opening was ≤40 mm, laterotrusion ≤5 mm and protrusion ≤7 mm. Data concerning subjective symptoms, evaluation of morphology and soft tissue function, and evaluation of TMJ function and muscular findings were entered as dichotome variables, while occlusion and mandibular range of movement were mainly given as numerical values.

All patients were treated according to a standardized protocol using a monodirectional distraction device (Medicon vertical mandibular distraction device, Medicon eG, Tuttlingen, Germany). Based on the calculation of the distraction vector, a guiding splint was prepared. A rigid wire was incorporated at a 90° angle to the planned direction of distraction ( Fig. 1 ).

Fig. 1
Guiding splint and indicator rod for vector transfer.

Calculation of the vector of distraction has been described elsewhere. An individual occlusal splint was fabricated to support occlusion during and after distraction because of the developing unilateral open bite.

An intraoral incision was made along the anterior border of the ascending ramus followed by exposure of the entire lateral surface of the ramus with the patient in general anaesthesia and with local infiltration with lidocaine–adrenalin. Sufficient space was created by bluntly stretching the soft tissue. The distraction device was applied on the lateral surface of the ramus and through a trocar entrance fixed loosely with one cortical screw. An indicator rod was fixed perpendicular to the distraction device, the surgical guide was placed on the teeth, and the correct vector of distraction was ensured by rotating the distraction device around the first screw until the rod and the wire were parallel ( Fig. 2 ). A second screw was inserted to secure the position of the distraction device. The remaining screw holes were pre-drilled and the distraction device removed to allow for osteotomy of the ramus either by use of a Lindeman bur or, since 2005, by piezoelectric (Mectron, Carasco, Italy) cutting of the bone. The lingual periosteum was kept attached to bone and the fracture completed. Free mobility was ensured. If present, third molars were removed at this time. The distraction device was reinserted and fixated in the pre-drilled screw holes. The device was activated to ensure movement without bony adherences of the lingual cortex and the wounds were sutured.

Fig. 2
Guiding splint and indicator rod in place during surgery.

The patients were given prophylactic antibiotics (2 MIU penicillin) during surgery and continued with oral penicillin (50 mg/kg/day) for 5 days, ibuprofen and paracetamol for pain control at doses corresponding to weight throughout the active distraction phase, and steroids (prednisolone 50–100 mg/day for 5 days). All patients were discharged the day after surgery and were scheduled for a check-up visit 5 days after surgery. At this visit, the patients or their relatives were instructed to activate the distraction device. The distraction rate was 0.8 or 1.2 mm per day (two or three daily activations of the device). Most patients started with a rate of 1.2 mm, which in some patients was reduced to 0.8 if significant pain was experienced during the distraction. In case of significant pain, activation was suggested divided into for example four activations (four times half turn) maintaining a rate of 0.8 mm/day.

The patients were followed weekly for splint adjustment and radiological control until the planned length had been obtained. Thereafter, the device was left inactive for a consolidation period of 10–12 weeks.

The device was removed under general anaesthesia and any other corrective surgery was performed if indicated. The patients continued further orthopaedic or orthodontic treatment as required to normalize their occlusion. Data concerning the surgical procedure were recorded and the occurrence of any difficulties or complications was evaluated ( Table 2 ).

Jan 24, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Functional changes following distraction osteogenesis treatment of asymmetric mandibular growth deviation in unilateral juvenile idiopathic arthritis: a prospective study with long-term follow-up
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