title: Assessing the mobility of the mandibular condyle by sonography.
abstract: OBJECTIVE
  Traditionally, the measurement of the maximal mouth opening was regarded as the mobility of the temporomandibular joint. The information, however, was not reliable. Sonography was often used to diagnose disc displacement in the temporomandibular joint and its validity was well established. The tool was also appropriate for measuring the outcome of temporomandibular disorders management. Therefore, the purpose of the study was to examine completely the reliability and error for evaluating the mobility of the mandibular condyle by sonography. In addition, the existing methods were modified to improve the repeatability.
  
  
  METHODS
  The reliability examinations included between-image and within-image explorations to represent the reliabilities of the image capturing and the mobility measuring, respectively. Sixty-two subjects were recruited to receive ultrasonic examination for condylar mobility. The images of the condyle in mouth closing and opening were captured and the horizontal displacement of the condyles was measured as the anterior translation of the condyle. To confirm that the probe did not move during mouth opening, a marker was placed between the skin and the ultrasonic probe as the landmark.
  
  
  RESULTS
  The results demonstrated that the intrarater and interrater reliabilities in the within-image test were 0.986 and 0.970 and the reliabilities in the between-image test were 0.904 and 0.857, respectively. The standard errors of measurement in the within-image and between-image tests were 0.04 cm and 0.09 cm, respectively.
  
  
  CONCLUSIONS
  Sonography is a reliable tool to assess condylar mobility and can be used to measure the treatment outcome for temporomandibular disorders.
authors.affiliation: Department of Physical Therapy, Hungkuang University, Taichung, Taiwan.
authors.forename: Han-Yu
authors.initials: HY
authors.lastname: Chen
authors.affiliation: Department of Physical Therapy, Hungkuang University, Taichung, Taiwan.
authors.forename: Shyi-Kuen
authors.initials: SK
authors.lastname: Wu
authors.affiliation: Department of Physical Therapy, Hungkuang University, Taichung, Taiwan ; Department of Rheumatology, Taichung Hospital, Department of Health, Taiwan.
authors.forename: Chuan-Chin
authors.initials: CC
authors.lastname: Lu
authors.affiliation: Department of Physical Therapy, I-Shou University, Kaohsiung, Taiwan.
authors.forename: Jia-Yuan
authors.initials: JY
authors.lastname: You
authors.affiliation: Department of Physical Medicine and Rehabilitation, Taichung Hospital, Department of Health, Taiwan.
authors.forename: Chung-Liang
authors.initials: CL
authors.lastname: Lai
keywords: mandibular condyle; reliability; sonography; temporomandibular disorders