Volumetric differences in the temporomandibular joint in patients with condylar hyperplasia in the active and passive...

Condylar hyperplasia (CH) is a progressive and deforming disease that modifies the anatomy of the temporomandibular joint (TMJ) structures. The present study aims to correlate the metabolic bone activity of the condyle measured by single photon emission computed tomography (SPECT) with the volumetry anatomical information from the condyle, fossa, and joint space provided by CT images in patients with CH in the active and passive states.

A cross-sectional comparative study was performed with a set of 116 images from healthy and diagnosed CH patients to compare volumetric measures of the TMJ. Images were acquired through a bone tissue mask using a 3D DICOM reconstruction for SPECT/CT and CBCT images and the threshold option for segmentation with standardized values for each tissue on the Hounsfield unit (HU) scale.

Differences were found (P 0.01), with greater condylar volume on the affected side in patients with active compared with passive CH. The volume of the glenoid cavity showed no differences in either state of CH (P > 0.05); however, there were differences for the volume of the joint space on the affected right side of hemimandibular elongation (HE) in the active state. The volume of the mandibular condyle on the affected side in CH cases was larger in HE cases in both active and passive forms (P 0.01) compared with healthy patients (controls). Similar results were presented for the glenoid cavity and joint space.

Volumetric anatomical evaluation of TMJ structures as well as information on condylar metabolic activity can be obtained from SPECT/CT. The present study showed a greater condylar volume on the affected side of the CH compared with the contralateral side, but there were more significant differences in the active than in the passive state.