Mandibular condylar hyperplasia (MCH) is a rare, idiopathic disorder, which can cause both functional and aesthetic problems. MCH has often been described in the literature, but a comprehensive analysis of the current literature on MCH has not been undertaken. This study presents a systematic review analyzing the efficacy of high condylectomy in patients with MCH, with an emphasis on its role in the management of unilateral condylar hyperplasia. A systematic search of the current literature on high condylectomy was performed to find studies with sample sizes of more than five patients using a set of inclusion/exclusion criteria. The search terms revealed 664 studies, of which only 11 articles with a total of 289 patients were eligible for inclusion. Due to differences in the presentation of data, a meta-analysis was not conducted. High condylectomy appears to be a relevant surgical method to correct unilateral condylar hyperplasia. The current literature indicates large variations in terms of aetiology, use of diagnostic tools, and preferred time of intervention. Thus, further systematic studies are needed to determine which procedures offer the best aesthetic and functional results.
Mandibular condylar hyperplasia (MCH) is a disorder of idiopathic origin in which pathological enlargement of the mandibular condyle is seen. Adams in 1836 was the first to describe the disorder, stating that it caused overdevelopment of the mandible and subsequent functional and aesthetic discomfort. Several case studies are found in the literature, and the rarity of the condition has been emphasized. This notion has, however, been challenged, and recent articles claim that the disorder is much more common in the population than most clinicians tend to believe.
Many theories have been presented; however, the pathological aetiology of the disorder remains unclear and is probably multifactorial. Some researchers have supported the ‘local circulatory theory’, which claims that the abnormal growth of the condyle is caused by an increased number of capillaries in the posterior superior anatomy of the condyles. Others have suggested that previous trauma, inflammation/infection of the temporomandibular joint (TMJ)/middle ear, osteomyelitis, osteochondromas, or chondromas may be initiating factors for MCH. Some authors suggest a hereditary, hormonal, or genetic influence, and TMJ loading has also been mentioned as a possible cause of MCH. Wolford and LeBanc have suggested that insufficient bone plate closure when cartilage from the proliferative layer is replaced by bone around age 20 years, e.g., as also seen in chondromas, osteochondromas, etc., could be a possible cause.
Another challenge is the lack of agreement in classification. In 1986, Obwegeser and Makek presented a classification system in which the disorder is separated into three categories: hemimandibular elongation (HE), with a horizontal growth vector; hemimandibular hyperplasia (HH), with a vertical growth vector; and a mixed form (HH + HE) that includes both pathological conditions. Typical clinical findings in HE are chin deviation towards the contralateral side and mandibular midline deviation towards the unaffected side. Clinical findings in HH are characterized as a compensatory overdevelopment of the maxilla on the affected side or an ipsilateral open bite with an occlusal cant. More recently, Wolford et al. suggested a simpler classification system in which condylar hyperactivity is suggested to be a pathological condition that causes overdevelopment of the condylar neck or head of the mandible, divided into two types: CH1 and CH2. This hyperactivity may be caused by various pathological conditions with different effects on the development of the facial skeleton. CH1 is caused by an accelerated growth of the normal growth mechanism, with a horizontal growth vector, and is divided into two entities: 1A, comprising bilateral abnormal growth of the mandibular condyles that is more or less symmetrical, and 1B, comprising unilateral, asymmetric abnormal condylar growth in which one side is more affected than the other, leaving an obvious asymmetrical condyle ( Fig. 1 ).
Furthermore, Wolford et al. stated that 1A is the more common condition and that 1B is rarer but causes a distinct facial asymmetry. Both of these types present at an early age (from childhood and to the mid-20s) and are mostly self-limited. CH2 is caused by an accelerated growth of the normal growth mechanism, with a vertical growth vector. The aetiology for this is unknown. CH2 is claimed to present at any age and is not self-limited. The differential diagnosis of CH2 includes osteochondromas, osteomas, benign tumours, hemifacial hypertrophy, etc. When these pathologies are present, a somewhat similar clinical appearance to CH2 is seen; however, the distinct difference is that the accelerated motion has an aetiology and therefore cannot be called CH2.
Figure 2 illustrates the comparison between the Obwegeser and Makek and Wolford classification systems. In this study the focus was placed mainly on cases where condylar hyperplasia is caused by an accelerated growth of the normal growth mechanism in the condyle due to an unknown pathology.
Today, no gold standard exists regarding the diagnosis of MCH. In addition, there is no agreement in the literature on the histopathology of MCH, and thus one cannot simply rely on a histopathological analysis of the hyperactive condyles to make the diagnosis of MCH. Prior attempts to classify the disorder histologically have been undertaken by Norman and Painter, Eslami et al., and Slootweg and Müller. Norman and Painter used histopathological findings based on 99m technetium (99mTc) scintigraphy to make an instrumental diagnosis of MCH. This was used to define the activity level of MCH. However, as later stated by Hodder et al., this qualitative method is sometimes inconsistent because the method is non-specific and hence not accurate enough to distinguish between active hyperplasia and other normally occurring active growth centres. Hodder et al. suggested that single photon emission computed tomography (SPECT) is more reliable because it has the ability to, more specifically, show condylar hyperactivity in a quantitative and accurate fashion. Several uptake values have been suggested, and a difference in uptake of 45% to 55% or more between the condyles is said to be an indication of unilateral condylar hyperplasia (UCH).
Wolford et al. have suggested that it is not necessary to use bone SPECT to show hyperactivity, and that hyperactivity can be shown by lateral cephalograms and clinical diagnostic techniques with serial assessments (6- to 12-month intervals). Additionally, it is suggested that bone scans are unnecessary or provide little information in bilateral cases. Additional diagnostic methods are clinical photographs, cast models in articulators, and conventional (CT) or cone beam computed tomography (CBCT) scans.
In the literature, the use of a high condylectomy in the treatment of MCH is controversial. The most important factor with MCH, and especially UCH, is that the disorder has a dynamic component and that a delayed intervention is possible after growth has ceased. However, this approach can be problematic because the development of asymmetry is very unpredictable and repair may thus be made more difficult. It is therefore relevant to discuss the effect of high condylectomy on patients with MCH because this surgical approach is designed to address the specific problem of the abnormal activity of the growth centre in the mandibular condyle.
The aim of this study was to undertake a comprehensive and systematic analysis of the current literature on the efficacy of high condylectomy in patients with MCH, and if possible to perform a meta-analysis of the results.
Materials and methods
In this systematic review, an attempt was made to identify the relevant literature concerning the effect of high condylectomy on both dental function and aesthetics in patients with UCH; the PRISMA statement was followed.
A systematic database search was performed using the National Center for Biotechnology Information to search MEDLINE (PubMed) and Embase. The search included articles published between 1994 and 2014 and included only articles in English and German, and was deliberately made wide to ensure that all relevant articles published on the subject could be identified.
The following two groups were compiled for the search using the following medical subject heading (MeSH) terms: group 1, “condylar hyperplasia” OR “facial asymmetry” OR facial asymmetry [mesh] OR “abnormal mandibular growth” OR “hemimandibular hyperplasia” OR “unilateral condylar hyperplasia” OR “hemimandibular elongation” OR “early high condylar hyperplasia” OR “chin deviation” OR “hemifacial hypertrophy” OR unilateral micrognathia OR laterognathia OR “hemimandibular hyperplasia”; and group 2, treatment outcome OR “mandibular high condylectomy” OR “high condylectomy” OR efficacy OR “efficacy of high condylectomy”. An additional hand search of the bibliographies of the articles that met the inclusion criteria was performed.
The screening was carried out using the following inclusion and exclusion criteria. Inclusion criteria: a relevant sample size of at least five patients to avoid singular case studies, a relevant background history of the patient to ensure that condylar hyperplasia was not of any other aetiology, an informative clinical description of the tools used to diagnose the condylar hyperplasia patient, and a thorough follow-up procedure with information that included the level of discomfort. Exclusion criteria: case reports with fewer than five patients, differential diagnoses causing facial asymmetry (including hemifacial microsomia, trauma to the mandibular condylar growth centre, and benign or malignant condyle tumours), no description of the diagnostic setup and follow-up, and cases in which the MCH was managed with procedures other than a high condylectomy or condylectomy.
The titles of articles were first screened for relevancy according to the inclusion criteria. If these were met, the abstracts were screened according to the inclusion and exclusion criteria. If the abstract did not give sufficient information, the full-text article was retrieved (see Fig. 3 ).
The following data were retrieved from the relevant articles and entered into an excel spreadsheet: author, year of publication, how the MCH was classified, the affected side and activity of the MCH, sample size, sex, age, aetiology, diagnostic methods, procedure and level of excised bone in the high condylectomy, surgical procedures performed in addition to the high condylectomy, patient discomfort, nerve damage, and the result after the high condylectomy was performed. The data are presented in Table 1 . The Cochrane Collaboration tool for the assessment of the risk of bias was used to evaluate selection, performance, detection, attrition, and reporting risk of bias.
|Author, year||Classification type||Affected side
|Number of patients||Sex F/M||Age range (mean)|
|Chiarini et al., 2014||Wolford||5 L
|5||2 F/3 M||14–17 (16.8) years|
|Jones and Tier, 2012||Obwegeser and Makek, Wolford||Unknown
13 CH1B, 3 CH2, and 1 CH2 due to osteochondroma
|17||15 F/2 M||Unknown|
|Villanueva-Alcojol et al., 2011||Obwegeser and Makek||22 R and 14 L
24 HH, 8 HE, 4 HH + HE
|36||25 F/11 M||11–42 (22.7) years|
|Saridin et al., 2010||Unknown||16 R, 16 L, 1 bilateral
|33/46 agreed to participate (31 subjects who were age- and gender-matched to the patient cohort served as a control group and entered the same research protocol)||18 F/15 M||19–48 (26.7) years|
|Brusati et al., 2010||Obwegeser and Makek, Wolford||Unknown||15||Unknown||12–42 (22) years|
|Wolford et al., 2009||Wolford||Unknown
36 CH1A, 18 CH1B
|42/54 High condylectomy, disc repositioning, and orthognathic surgery
12/54 Orthognathic surgery only
|36 F/18 M||13–24 (16.6) years|
|Deleurant et al., 2008||Obwegeser and Makek||Equally affected
|7/47 met criteria||6 F/1 M||13–25 (16.3) years|
|Lippold et al., 2007||Obwegeser and Makek||4 L, 2 R
|6||3 F/3 M||22–30 (27) years|
|Wolford et al., 2002||Wolford||Unknown
24 CH1A, 13 CH1B
|25/37 High condylectomy and orthognathic surgery
12/37 Orthognathic surgery only
|20 F/17 M||13–25 (16.7) years|
|Appel et al., 1997||Obwegeser and Makek||Unknown
6 HE, 7 HH, 3 HE + HH, 1 deformed condyle
|17||Unknown||10–36 (22.5) years|
|Chen et al., 1996||Obwegeser and Makek||6 R and 3 L
6 HH, 3 HE + HH
|9||7 F/2 M||18–58 (28.2) years|
|Author, year||Orthodontic treatment||History (family history, prior trauma)||Prior symptoms||Clinical examination||Clinical photos/study models|
|Chiarini et al., 2014||Yes, preop.||Unknown||Unknown||Mild facial asymmetry, canting of the occlusal plane, active laterognathia, no lateral hyperplastic mandibular lower border||Yes/yes|
|Jones and Tier, 2012||Yes, preop./postop.||Unknown||Unknown||Yes, no description||Yes/yes|
|Villanueva-Alcojol et al., 2011||Yes, postop.||No neoplasia/dysplasia||13 patients had TMJ mild pain/clicking||Occlusal disturbance and/or chin deviation towards the opposite side||Yes/yes|
|Saridin et al., 2010||Unknown||Unknown||Unknown||Made according to the RDC/TMD||Yes/yes|
|Brusati et al., 2010||Yes, preop.||Unknown||Unknown||Yes, no detail||Yes/yes|
|Wolford et al., 2009||Unknown||Unknown||No TMJ pain, no jaw dysfunction, no dietary dysfunction||MIO and lateral excursion||Yes/yes|
|Deleurant et al., 2008||Yes, preop.||Unknown||Unknown||Unknown||Yes/yes|
|Lippold et al., 2007||Yes, 5 patients preop. and postop. finishing 6 weeks after||Unknown||2 patients moderate, 3 patients mild, 1 patient no TMJ dysfunction according to Helkimo index||TMJ evaluation according to Helkimo index/electronic digital sliding calliper measurement on inter-incisal opening/chin deviation, tilting of occlusal plane||Yes/yes|
|Wolford et al., 2002||Yes, preop.||Approx. a third of bilateral cases had a family history||Mean TMJ 0.6; mean jaw function 3.6; mean diet 0.7||MIO and lateral excursion||Yes/yes|
|Appel et al., 1997||Unknown||Unknown||Symptoms started 2 years prior: pain, swelling, movement problems, but not that severe||Unknown||Yes/yes|
|Chen et al., 1996||Yes, postop.||No prior trauma||No TMJ complaints, no orofacial pain with opening||Unilateral enlargement of the mandibular condyle (with down bowing), condylar neck, ramus, and mandibular body; chin deviation to the unaffected side||Yes/yes|
|Author, year||Radiological examination||SPECT bone scintigraphy a||Bone excised||Histopathological examination||TMJ symptoms|
|Chiarini et al., 2014||CT/cephalograms||Yes, 99mTc||6 mm||None||None (mean VAS 2.4)|
|Jones and Tier, 2012||Lateral/posterior/anterior cephalometric projections||Yes, 99mTc||6 mm||None||Unknown|
|Villanueva-Alcojol et al., 2011||Pantomograms/postero-anterior and lateral cephalograms||Yes, 99mTc||4–5 mm||18/36 classified by Slootweg and Müller||None, not detailed|
|Saridin et al., 2010||Yes, no details||Yes, 99mTc||≥5 mm||None||GCP = 0 for 22/33, GCP = 1 for 6/33, GCP = 2 for 2/33; 3/33 excluded due to inconsistent data in the questionnaire|
|Brusati et al., 2010||Pantomograms/postero-anterior and lateral cephalograms||Yes, 99mTc||5–7 mm||None||8 patients had excellent articular function both objectively and subjectively; 6 patients had additional deviation in opening, lateral excursion reduced on the affected side; 1 patient had deviation in mouth opening, lower lateral excursion|
|Wolford et al., 2009||Lateral cephalometric projections||None||3–5 mm||None||Little improvement|
|Deleurant et al., 2008||Pantomograms||Yes, 99mTc||2–3 mm||None||Maximum mouth opening reduced by 50% after HC; regained 20% with OS, achieving in total about 70% of the initial mean value. In T6, 5 patients showed a gain of 83–95% and 2 patients plus 2% and plus 27%, respectively|
|Lippold et al., 2007||Pantomograms/frontal lateral cephalograms/CT||Yes, 99mTc||Unknown||According to Eslami et al.; affected condyle showed more signs similar to condylar arthrosis||3 patients improved in TMJ dysfunction postop. (Helkimo index)|
|Wolford et al., 2002||Lateral cephalometric projections||None||3–5 mm excised||None||Mean TMJ 0.3|
|Appel et al., 1997||Yes, unknown||Yes, 99mTc||1.5–3 mm excised||None||No symptoms|
|Chen et al., 1996||Pantomograms||6 patients 99mTc||Unknown||None||Unknown|
|Author, year||Pain||Results||Depression/nerve damage||Additional surgery|
|Chiarini et al., 2014||Swelling, trismus, and pain resolved within a month||Satisfactory TMJ function and stable occlusion||Unknown/none||None|
|Jones and Tier, 2012||Unknown||Satisfactory results where activity in condylar hyperplasia||Unknown||Orthognathic surgery in 17 patients, costochondral graft in 3 patients|
|Villanueva-Alcojol et al., 2011||Unknown||Satisfactory at 4.3 years follow-up||Unknown||6 patients (4 BSSO, 2 mentoplasties, 1 angle prostheses)|
|Saridin et al., 2010||3 patients myofascial pain; 0 patients myofascial pain with limited opening; 1 patient disc displacement without reduction with limited opening; 2 patients arthralgia symptoms; 1 patient osteoarthritis; 5 patients osteoarthrosis; 3 patients had more than one diagnosis||Satisfactory at 4.3 years follow-up||Not different from control group, therefore this can be disregarded||Unknown|
|Brusati et al., 2010||1 patient pain and noise||Satisfactory; when active condylar hyperplasia, should be considered especially in younger patients||Unknown||Recommended postsurgical physiotherapy and additional orthognathic surgery for aesthetic correction|
|Wolford et al., 2009||None||Satisfactory; only 1/42 grew back in class III, while all 12 patients in the control group with no HC had relapse||Unknown||Recommended TMJ articular disc is repositioned and stabilized to cover the articulating surface of the new condyle or defer correction until full growth and then only orthognathic surgery|
|Deleurant et al., 2008||Unknown||Satisfactory||Unknown||Recommended 1 year later BSSO and Le Fort I for optimal aesthetic results|
|Lippold et al., 2007||None||Satisfactory||Unknown||Recommended Le Fort I osteotomy in addition|
|Wolford et al., 2002||Mean jaw function 2.4/mean diet 0.5||Satisfactory; only 1/25 grew back in class III, while all 12 patients in the control group with no HC had relapse||Unknown||If an active condylar hyperplasia, then condylectomy (usually in younger patients); if inactive condylar hyperplasia, no condylectomy as orthognathic surgery is sufficient|
|Appel et al., 1997||No pain||Unsatisfactory||Unknown/1 patient, auriculotemporal nerve||7 patients underwent a second surgical intervention after 6–14 months; 3 patients are still planned for the procedure; 6 patients denied a second surgical intervention|
|Chen et al., 1996||Unknown||Satisfactory||Unknown||Additional surgery was performed to level out the occlusal plane|