Age‐Stratified Efficacy of Open Anchoring Versus Hyaluronate Injection for TMJ Anterior Disc Displacement Without Reduction: A Prospective Study

BACKGROUND: Objective measures of long-term functional recovery and possible age-related treatment patterns in temporomandibular joint anterior disc displacement without reduction (TMJ ADDWoR) remain insufficiently characterized. This study compared open disc repositioning with anchoring and conservative treatment, with particular emphasis on prespecified age-stratified functional outcomes. METHODS: This prospective, non-randomized study enrolled 68 adults with MRI-confirmed unilateral TMJ ADDWoR between January 2024 and March 2026. After receiving standardized information about both treatments, patients selected open anchoring surgery (n = 32) or conservative treatment (n = 36). Nine patients were lost to follow-up because returning at the scheduled time was impractical; complete-case analyses included 28 surgical and 31 conservative patients. Pain intensity, maximum mouth opening (MMO), MBF and surface electromyographic asymmetry indices (AIs) of the bilateral masseter and anterior temporalis muscles were assessed at baseline and 12 months. RESULTS: Pain and MMO improved significantly within both groups. At 12 months, MBF was higher after surgery than after conservative treatment (mean difference, 23.17 kg; 95% CI, 6.09 to 40.24; p = 0.009) and bite AI was lower after surgery (mean difference, -14.15 percentage points; 95% CI, -24.14 to -4.16; p = 0.006). Among patients aged ≤ 30 years, MBF improvement was numerically greater after surgery than after conservative treatment (28.14 ± 43.51 vs. 7.07 ± 23.81 kg; p = 0.056), representing a descriptive trend. The 12-month bite AI was also lower after surgery in this age stratum (14.26% ± 13.94% vs. 30.86% ± 26.22%; p = 0.015). Differences in patients aged > 30 years favoured surgery numerically but were not significant. Treatment-by-age interactions were not significant for MBF change (p = 0.514) or 12-month bite AI (p = 0.555). CONCLUSION: Open disc repositioning with anchoring was associated with greater bite-force recovery and more symmetric superficial jaw-elevator activation during clenching. The age-stratified findings showed a potentially clinically relevant pattern favouring surgery, particularly among patients aged ≤ 30 years. These exploratory findings warrant confirmation and do not establish an age-specific treatment threshold.