The Management of Condylar Hyperplasia - Essay Example

A Systematic Review of the Management of Condylar Hyperplasia Introduction Condylar Hyperplasia is a developmental disorder which is characterized by excessive growth of the condyle and the mandible that leads to facial asymmetry. The size of the growth is averagely twice or thrice the size of an average condyle hence the asymmetry. Based on clinical, radiographic and histological findings, it can be described as having two types: Hemimandibular Hyperplasia (HH) and Hemimandibular Elongation (HE).1 The aetiology of the disorder is not known yet but the growth is probably caused by persistent or resumed activity of the pre-cartilaginous cells of the condyle growth zone but others have suggested a change in the local growth hormone control of the cell10. Hemimandibular Hyperplasia involves excessive growth on one side of the mandible which extends to the condyle and even the neck and the facial asymmetry occurs on that side. However it does not alter the chin position. Hemimandibular Elongation is a bit different where there is noticeable elongation on one half of the mandible which leads to the chin being displaced. This is the most common type of condylar hyperplasia to occur. . The resulting mandibular asymmetry is often responsible for malocclusion and functional problems. Bone scans (radiography) can be used to detect the excessive growth of the condylar and then treatment options considered depending on the size of the growth. Since bone scintigraphy identifies patients with an active condylar growth centre who should undergo a condylectomy, bone scintigraphy of the mandibular condyles is therefore a useful indicator of continued bone activity3. In condylar hyperplasia, a bone scan is useful to determine the side that has an active, abnormal condylar growth center8. An addition of bone scintigraphy to the diagnostic evaluation of patients suspected of having condylar hyperplasia may be most effective in unilateral cases, especially if applied after puberty, when condylar growth should have ceased. Bone scans have been found to be inconclusive in younger patients and those with slow growing condylar hyperplasia. Clinical examination will confirm facial asymmetry with a number of key features apparent on plain radiographs. A sound understanding of the aetiology, nature of the deformity, clinical presentation, options for treatment, and timing of treatment is required to achieve optimal treatment outcomes. The clinician may interpret bone scans by subjective evaluations or by quantitative measurements. Interpretation of the bone scan images without quantification is subjective and may lead to false positive and negative diagnoses that may cause delay or incorrect treatment. Plain radiographs are, however, essential as an initial screen. Initial presentation is often with malocclusion and mandibular asymmetry (deviation of the chin to the unaffected side). Other presentations are as dysfunction of the TMJ or primary facial asymmetry.11 High condylectomy is usually the treatment of choice in those patients with active hyperplastic growth, whilst the rest are managed with a combination of orthodontic treatment and orthognathic surgery2. The high condylectomy arrests the excessive and disproportionate growth of the mandible by surgically removing a principal mandibular growth site. Secondary correction by mandibular or maxillary osteotomies or both is appropriate to correct any residual occlusal and facial asymmetry. However, if osteotomies are done while condylar activity persists then further deformity may develop. Consequently, accurate assessment of cessation of excess activity in the condyle is needed. Objectives The aim of the current study was to test the role of the SPECT bone scan to determine whether such imaging is mandatory before deciding upon definitive management in condylar hyperplasia. Methods The study was a retrospective review of patients presented to a facial deformity clinic with mandibular asymmetry between 2002 and 2009. The inclusion criteria involved patients with suspected condylar hyperplasia who had no orthodontic treatment available to be followed up, and clinical examination every six months for at least a year, and who consented to undergo SPECT examination. The clinical examination was presentation as a baseline and then at regular follow up to monitor the progression of facial asymmetry. All patients had a routine clinical examination to look for signs of condylar hyperplasia. Records of the occlusion were taken with plaster models and wax bite to permit changes with time to be observed in serial models. Plain radiographs which included orthopantograms were obtained in all cases. All patients then underwent a Single Photon Emission Computed Tomography (SPECT) test. All available bone scans were digitally loaded and a region of interest, which was of the same size in both condyles, was drawn around the condylar region on the left and right sides on the SPECT images. During region of interest analysis, the average number of counts per pixel in a group of contiguous pixels in an image was determined1. The reconstructed images in the Trans axial and coronal views were then sliced and the difference in isotope uptake between the affected condyle and the contralateral condyle was expressed as a percentage. TMJ function was objectively evaluated and maximum interincisal opening and lateral excursions were measured in all patients. For those undergoing TMJ surgery, additional evaluations included subjective evaluations with numerical visual analog scales to assess TMJ pain, jaw function and diet. Results A total of seventy one patients participated in the study in which condylar hyperplasia was suspected and subsequently underwent a SPECT scan. Fifty four of the participants were females and seventeen male and their age group ranged from 10-14 years with a mean age of 19.5 years. Thirty seven of the patients were diagnosed with positive bone scans hence presence of active condylar hyperplasia. A SPECT scan was considered asymmetrical if the difference in activity between the affected and contralateral condyles was greater than 10%4. A hyperactive condyle was defined by the clinical signs of progression of the mandibular asymmetry in combination with a significant asymmetrical scan. The patients diagnosed with condylar hyperplasia based on these criteria could be treated conservatively if there was no clinical progression of the asymmetry or if the bone scans revealed symmetrical activity. Surgical treatment (a high partial condylectomy) was performed if the unilateral condylar growth was significant. Thirty eight patients had a high condylar shave undertaken which included five patients with normal bone scans. The condylar head was approached via a pre-auricular approach with temporal extension and reflection of the temporal fascia. Access to the joint capsule was via an inverted L incision with the disc mobilised to access the condylar head. Up to 5 mm of the condylar head was removed following replacement of the disc. Closure was in two layers with the placement of a drain. Post operatively, all patients were advised to undergo physiotherapy in the form of active mobilisation of the temporomandibular joint. The remaining thirty three patients were managed with other treatments with six of these lost to follow up. Conclusion Bone scan helps to identify those suitable for high condylar shave. It is useful in managing younger patients, and potentially avoiding orthognathic surgery. Condylar hyperplasia presents a difficult surgical problem where its management dependents on the fact that abnormal condylar growth is continuing. The results show that depending on the reading of the SPECT study, it could suggest that the bone was still growing and corrective surgery should be delayed or interceptive surgery offered if the condition was severe, particularly when a high difference was detected. It can be concluded the use of SPECT and the percentage difference in the isotope uptake of the two condyles, can be accurate enough to separate active growth from growth cessation of the condyle. A longer follow up period and a larger group of patients are however needed to confirm this finding. Bone scanning in patients with suspected condylar hyperplasia offers an independent method for the identification of an abnormal growth center5. In the case of condylar hyperplasia, rather than planar bone scintigraphy, SPECT scanning appears to be a significantly better diagnostic tool6. The patients with a mandibular asymmetry were evaluated based on their history, clinical assessment and bone scans (which is considered to be an important part of the standard workup for patients with suspected condylar hyperplasia). This evaluation was performed to assess whether the asymmetry was caused by the on-going activity of the condylar growth centre. In all cases in which a positive SPECT scan was confirmed with clinical progression of the asymmetry, a high, partial condylectomy of the affected side was performed. For the patients who exhibited marginal increase of uptake in the affected condyle without clinical progression of the asymmetry, a more conservative policy was adopted. Optimal treatment plan for a patient with condylar hyperactivity depends on the accurate assessment of the on-going activity of the condylar growth centre. An enlarged but inactive mandibular condyle is left intact and corrective surgery is directed at the ramus or at the body of the mandible, mostly with orthognatic surgical procedures. Conversely, an actively growing condyle with an associated progressing deformity is usually treated by high, partial condylectomy with or without additional surgery to correct any residual deformity7. The basic orthodontic goals are the same as in any conventional orthognathic surgical patient. The goal is to align and level the teeth over the basal bone, and to remove dental compensations regardless of the magnitude of skeletal and dental misalignment. Patients with arrested CH can usually be treated with routine orthodontics and orthognathic surgery. Active CH however cannot be predictably controlled with orthodontics or orthopaedic mechanics. The patient’s desire for treatment has to be taken into account as well as the clinical picture. In conclusion, the study has shown that quantitative bone SPECT used to compare the mandibular condyles is a helpful investigation in the assessment of bone activity that may lead to facial and mandibular asymmetry in growing and non-growing patients. Read More