Fig. 1

Surgical procedures in the control (a–e) and experimental groups (a–f). a Exposure of the temporomandibular joint (TMJ) complex. Te: temporal bone, Co: condylar process, yellow arrow: articular disc. b Measurement of the preoperative ramus height in both groups. Mr: mandibular ramus, Za: zygomatic arch. c Cutting of the anterior and posterior disc attachments. Te: temporal bone, Co: condylar process, yellow arrow: articular disc. d Removal of the lateral one-fourth of the articular disc. Te: temporal bone, Co: condylar process, yellow arrow: lateral one-fourth of the articular disc. e Placement of grid grooves measuring 2 columns × 2 rows using an ultrasound osteotome on the surface of the glenoid fossa. White arrow: the sagittal fracture line of the mandibular condyle from the lateral pole of the condyle to the medial side of the condylar neck. Te: temporal bone, Co: condylar process. Black arrow: grid grooves measuring “2 × 2” in the shape of a “#”, representing “2 columns × 2 rows”. f Removal of the medial lateral pterygoid muscle attachment on the fracture segments (red arrow: broken ends of the lateral pterygoid muscle attachment) (Te: temporal bone, Co: condylar process)