Incidence and Clinical Outcomes of Plate Displacement and Plate Fracture Following Semirigid Sliding Plate Fixation After Bilateral Sagittal Split Ramus Osteotomy: A Longitudinal Cohort Study.

BACKGROUND

Plate displacement and plate fracture are occasionally observed after semirigid sliding plate fixation following bilateral sagittal split ramus osteotomy (BSSRO), but their clinical significance remains unclear.

PURPOSE: To estimate the incidence and identify the characteristics and clinical significance of plate displacement and plate fracture following semirigid sliding plate fixation after BSSRO.

STUDY DESIGN, SETTING, SAMPLE: Retrospective cohort study at Pusan National University Dental Hospital, Republic of Korea. Patients with skeletal Class III malocclusion who underwent mandibular setback by BSSRO with bilateral semirigid sliding plate fixation by one surgeon (January 2012 to February 2025); concomitant procedures were permitted.

EXCLUSIONS: mandibular advancement, non-BSSRO procedures, other fixation, incomplete records, prior orthognathic or temporomandibular joint surgery, and/or craniofacial pathology.

PREDICTOR VARIABLE: Plate-related event status: no event, plate displacement without fracture, or plate fracture.

MAIN OUTCOME VARIABLE: Clinical significance, measured using 4 subject-level outcomes: refixation surgery, occlusal relapse, idiopathic condylar resorption, and duration of postoperative orthodontic treatment.

COVARIATES: Age, sex, body mass index, mandibular setback magnitude, Le Fort I osteotomy, genioplasty, and other adjunctive procedures.

ANALYSES: Kruskal-Wallis and Fisher's exact tests; between-group differences with 95% CIs; linear regression adjusted for age and sex; P < .05.

RESULTS

Of 1,363 patients identified, 207 (15.2%) were excluded and 1,156 (84.8%) subjects were included (mean age 22.7 [5.0] years; 585 [50.6%] male). Plate displacement occurred in 250 (21.6%; 95% CI, 19.3 to 24.1) subjects, including 14 (1.2%; 95% CI, 0.7 to 2.0) with fracture. Nearly all (99.2 and 92.9%, respectively) were first detected within 3 months. Events were associated with male sex, higher body mass index, and absence of Le Fort I osteotomy (all P ≤ .01) but not setback magnitude. Refixation was required in 1 (0.1%) subject without a plate-related event. Orthodontic treatment duration (adjusted difference, displacement vs no event, 0.8 months; 95% CI, -0.3 to 1.9), occlusal relapse, and idiopathic condylar resorption did not differ by event status (all P ≥ .1).

CONCLUSIONS AND RELEVANCE: Plate displacement and plate fracture were not associated with adverse subject-level clinical outcomes and in isolation should not be interpreted as fixation failure requiring intervention; active surveillance may be indicated.