Innovative orbital rim repositioning with mortise-tenon joints: a fusion of modern surgery and traditional Chinese woodcraft

Orbital rim repositioning is a pivotal step in lateral orbitotomy. This study aims to introduce a novel mortise-tenon joint fixation (MTF) technique inspired by traditional Chinese woodcraft for lateral orbital rim reconstruction. This retrospective case series analyzed outcomes in patients with thyroid eye disease (TED) undergoing balanced orbital decompression surgery using MTF. The clinical outcomes, the number of surgical implants used, and hospitalization costs were analyzed. Additionally, an orbital model of the same laterality, derived from another patient treated with titanium plate-and-screw fixation (PSF), was selected as the comparator for the three-dimensional finite element analysis. Analysis was conducted with masseter muscle fixation and the application of occlusal force on the masseter muscle. Nine TED patients (12 orbits) undergoing MTF reconstruction were enrolled. A mean proptosis reduction of 5.3 ± 0.9 mm was achieved. No complications such as severe hemorrhage, vision loss, or orbital rim displacement were observed. Finite element analysis showed that maximum stress was lower with MTF than with PSF: 8.59 MPa vs. 91.33 MPa (masseter muscle fixation) and 16.33 MPa vs. 91.20 MPa (force applied). Maximum displacement was also lower for MTF: 0.010 mm vs. 0.014 mm (masseter muscle fixation) and 0.026 mm vs. 0.033 mm (force applied). Implant material expenses in hospitalization costs decreased by $288.43-$412.00, representing an approximate 84.3% reduction compared to PSF. In summary, the MTF technique demonstrates safety, effectiveness, and biomechanical advantages for orbital rim repositioning during lateral orbitotomy. It also reduces patient costs, offering a promising alternative to traditional fixation methods.