Bone scan analyses and clinical assessment are used to diagnose unilateral condylar hyperactivity (UCH). This review compares the diagnostic accuracy of planar and SPECT bone scans. Studies diagnosing patients with possible UCH using bone scans, published between 1968 and 2008, were included in this review. Of 15 articles that met the inclusion criteria, 7 presented results in sufficient detail to calculate index test characteristics. Three control studies show that the difference in uptake values of the left and right condylar regions in the normal population does not exceed 10%. The pooled sensitivity of the planar bone scan ( n = 130) was 0.71 (95% confidence interval: 0.57–0.82), which was significantly lower ( p = 0.04) than that of the bone SPECT technique ( n = 88), which was 0.90 (0.79–0.97). The pooled specificity of the SPECT scan was 0.95 (0.82–0.99), which did not significantly differ ( p = 0.58) from that of the planar scan (0.92 (0.83–0.97)). Future studies should include a diagnostic analysis of the data, including two-by-two contingency tables, so the accuracy of the diagnostic test may be evaluated. Bone scans are best performed using SPECT, conducting a quantitative analysis by calculating the percentile differences between the left and right condylar regions.
Unilateral condylar hyperactivity (UCH) is a rare condition, resulting from a growth disorder of the temporomandibular joint (TMJ). Patient vary in age and consist of young adolescents and older, non-growing patients. UCH can produce facial asymmetry that is clinically characterized by varying degrees of gross mandibular overgrowth of the affected side, malocclusion with canting of the occlusal plane, unilateral open bite, cross-bite, and deviation of the chin away from the affected side . Accurate assessment of the active condylar growth center is important because corrective surgery of the facial asymmetry is usually not performed if there is still a possibility of progression of the asymmetry due to UCH.
UCH is diagnosed on the basis of anamnestic and clinical findings and by evaluating conventional radiographs of the patient. Cisneros was the first to use bone scintigraphy to study patients with mandibular asymmetry . Radionuclide bone scanning is an instant method of comparing the differential activity between the normal and abnormal condyles, reflecting the relative growth rates at the time of the investigation . Two frequently used scanning techniques are planar bone scanning and single photon emission computed tomography (SPECT), both of which use the same basic technology. SPECT produces a tomographic bone scan image that may be more reliable than planar scanning . The 2 scanning techniques can be analyzed in a qualitative (subjective) and quantitative (objective) manner.
The objective of this study is to review relevant studies to estimate the diagnostic value of bone scans for the diagnosis of UCH. The use of different methods of quantification, and the possible use of normal values in quantitative studies of patients with possible UCH is reviewed.
Materials and methods
A comprehensive computer literature search of the PubMed database was conducted in November 2008. Planar and SPECT bone scintigraphy were the 2 diagnostic imaging techniques reviewed. A sensitive search strategy was used, using key words, which yielded more than 1035 search results, which were checked for relevance using their titles and abstracts ( Fig. 1 ). The reference lists of these studies and reviews were manually searched to identify any additional eligible studies; these references were also included in the final study selection. The search was restricted to articles published in the English language, human adult studies, and studies in peer-reviewed journals with an available abstract, that were published between 1968 and 2008.
The studies were considered eligible for the literature review if they met the following inclusion criteria: clinical studies that evaluated the diagnostic performance of planar and SPECT bone scans in patients suspected of having UCH; a study population of at least 10 patients ; and studies reporting normal individuals or patient studies presenting diagnostic accuracy (e.g. sensitivity and specificity) or enough data to enable calculation of sensitivity and specificity.
If more than one study by the same author was included in the review, the patient demographics were assessed to rule out overlap. Studies with possible overlap were excluded from the meta-analysis. All studies of which the eligibility was unclear were retrieved and the final decision was made on the basis of the full-length article.
Relevant data (e.g. patient and study characteristics) were extracted from the studies and scored in a standardized manner ( Table 1 ). Data on diagnostic performance, quantification methods, and the inclusion of a control group with normal values are given in Table 2 . The studies that evaluated a control group of patients without a medical history of TMJ disorders are given in Table 3 .
|Study (first author)||Year of publ.||Origin||Design||Time period||Mean age/range (yr)||Tracer/amount||Follow up/range (months)|
|C isneros||1984||U.S.||Retrospective||1981–1983||NR/3–23||99m Tc-MDP/NR||NR|
|H ampf||1985||Finland||Retrospective||1975–1982||26.2/9–52||99m Tc-DPD/NR||6.2/(1–39)|
|S lootweg||1986||The Netherlands||Retrospective||NR||24.5/14–59||NR||–|
|R obinson||1990||U.K.||Retrospective||NR||NR/12–32||99m Tc-MDP/600 MBq||NR|
|H enderson||1990||U.K.||Retrospective||1979–1987||NR/17–35||Tc-HMDP/600 MBq||≥30|
|G ray||1990||U.K.||Retrospective||1983–1988||25.8/15–55||99m Tc-MDP/NR||–|
|G ray||1994||U.K.||Retrospective||NR||21.5/15–55||99m Tc-MDP/550 MBq||–|
|P ogrel||1995||U.S.||Prospective||NR||30.8/NR||99m Tc-MDP/0.2–0.3 mCi/kg||36|
|B ohuslavizki||1996||Germany||Prospective||NR||NR/15–35||99m Tc-MDP/450–650 MBq||36|
|C han||1999||Australia||Retrospective||1993–1996||20.0/11–22||99m Tc-MDP/1000 MBq||–|
|H odder||2000||U.K.||Retrospective||NR||20.0/13–34||99m Tc-MDP/500 MBq||32.0/(12–60)|
|P ripatnanont||2005||Thailand||Prospective||1998–2003||12–46||99m Tc-MDP/20 mCi||12.0|
|S aridin||2007||The Netherlands||Retrospective||1988–2002||21.5||99m Tc-HDP/600 MBq||–|
|N itzan||2008||Israel||Retrospective||1980–2004||27.8/11–80||99m Tc/NR||–|
|S aridin||2008||The Netherlands||Retrospective||1988–2007||21.3/11.5–43.2||99m Tc-HDP/ 600 MBq||9.0(1.8–16.2)|