[Correlation between temporomandibular joint osteoarthrosis and coronoid process].

Objective: To investigate the morphological characteristics of coracoid process in different stages of temporomandibular joint osteoarthrosis (TMJOA), and to provide theoretical data for clinical and anatomic study. Methods: A total of 290 patients who were diagnosed with TMJOA in the Department of Temporomandibular Joint, Kunming Medical University School and Hospital of Stomatology from January 2015 to February 2021 were collected, including 69 males and 221 females, with an average age of 35.1±13.7 years (16-69 years old), 64 cases of unilateral lesions (64 sides), and 226 cases of bilateral lesions (452 sides). According to the TMJOA X-ray staging standard put forward by Ma Xuchen in 2005, the affected joints were divided into stage I (227 sides), stage Ⅱ (38 sides), stage Ⅲ (164 sides) and stage Ⅳ (87 sides). Twenty-six patients without clinical and imaging manifestations of temporomandibular disorders in the Department of Radiology, Kunming Medical University School and Hospital of Stomatology from October 2020 to June 2021 were selected as the control group, including 8 males and 18 females. The average age was (34.3±13.9) years (17-60 years). The dicom data of each group were imported into SimplantPro11.04 software to measure the height of coracoid process, anteversion angle and the ratio of coracoid vertex to mandibular corner to condylar vertex to mandibular angle. R 3.6.1 was used to analyze the difference of the morphological characteristics of coracoid process between in the affected side of TMJOA and in the both sides of the control group, in the healthy side and the affected side of unilateral patients and in different stages of TMJOA. Results: The height of the coracoid process [(16.26±2.81 mm)], the ratio of the coracoid process vertex-mandibular angle point and the condyle vertex-mandibular angle point distance [0.96(0.92,1.01)] on the affected side of TMJOA were significantly higher than those in the control group [(15.31±3.03)mm;0.95(0.89、0.99)] (t=2.18, P=0.033; t=2.87, P=0.004). There was no significant difference between the ante-version angle and the control group (t=-1.37, P=0.176). The ratio of the distance between the apex of the coracoid process and the apex of the mandibular angle to the apex of the condyle and the angle of the mandible in the affected side of unilateral patients was significantly greater than that in the healthy side (t=-3.46, P=0.001). There was no significant difference in coracoid height, coracoid anteversion angle and the healthy side (t=-1.85, P=0.069; t=-0.06, P=0.955) in different periods. The intra-group analysis showed that there was no significant difference in the height of the coracoid process in different stages (F=0.37, P=0.774). There was no significant difference in the ante-version angle of the coracoid process: stage I, stage Ⅱ, and stage Ⅲ (P>0.008), but all were significantly smaller than stage Ⅳ (PⅠ-Ⅳ<0.001, PⅡ-Ⅳ=0.009, PⅢ-Ⅳ<0.001). The ratio of the distance between coracoid apex-mandibular angle and condyle apex-mandibular angle: there was no significant difference in stage I, stage Ⅱ, and stage Ⅲ (P>0.008), and stage I and stage Ⅲ were significantly smaller than stage Ⅳ (P<0.001). Conclusions: The coracoid height and the ratio of the coracoid apex-mandibular angle to the condyle apex-mandibular angle distance on the TMJOA side were significantly greater than those without temporomandibular joint disorders. The bone deposition was mainly concentrated in the upper and posterior part of the condyle. TMJOA had a certain correlation with the height of the coracoid process.