Rationality assessment of postoperative disc-condyle position following TMJ arthroscopic disc repositioning operation: a retrospective MRI study

Objectives To systematically evaluate the postoperative disc-condyle relationship—including both structural position and functional mobility—following bilateral arthroscopic disc repositioning (Bi-ADRO) for temporomandibular joint disorders. Material and methods This retrospective study initially enrolled 90 consecutive patients who underwent MRI. After applying predefined inclusion and exclusion criteria, 31 patients without anterior disc displacement (non-ADD) were assigned to the symptomatic control group (group N), and 59 patients (101 joints) diagnosed with anterior disc displacement without reduction (ADDWoR) treated by Bi-ADRO constituted the surgical group (group A). Postoperative MRI was performed at 1, 3, and 6 months (A 1M ~ A 6M ). Statistical analyses were conducted using IBM SPSS Statistics v.27.0, with p < 0.05 considered statistically significant. Results Preoperatively, group A 0 showed significantly lower maximum mouth opening (MMO) and greater disc-condyle angular deviations than group N ( p < 0.001). After Bi-ADRO, MMO improved progressively at all follow-ups ( p < 0.05). Sagittal disc position improved markedly in A 1M ~ A 6M , but coronal alignment did not change significantly. Disc mobility increased most markedly by the third month, with vertical motion exceeding horizontal motion, whereas condylar mobility remained predominantly horizontal. At 6 months, 51.5% of joints achieved a disc-condyle angle between 0° and -60°. Changes in disc-condyle angle from 1 to 6 months were negatively correlated with the surgical disc position (A 1M~3 M : p < 0.001, r = -0.457; A 1M~6 M : p < 0.001, r = -0.499). Conclusion Bi-ADRO restores sagittal disc position and improves joint mobility in patients with ADDWoR, although coronal disc displacement may persist. The degree of surgical overcorrection influences postoperative disc stability and coordinated disc-condylar movement. These findings support the use of quantitative MRI-based angular targets to optimize surgical outcomes, though longer-term studies are needed to confirm durability.