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Strain Gauge Analysis of Three Different Sagittal Split Ramus Osteotomy Modifications
Frederico Felipe Antonio de Oliveira Nascimento1, John Paul Stella2, Leandro Eduardo Klüppel3
1Unidade de Cirurgia e Traumatologia Bucomaxilofacial, Hospital de Base de Brasília, Setor Médico e Hospitalar sul 101, Área especial sem número, Brasília, 70330-150 DF Brazil.
Journal of Maxillofacial and Oral Surgery
|July 30, 2026
Summary
The Wolford sagittal split osteotomy (SSRO) design offers superior screw stability and stress distribution compared to Epker and Wyatt designs. Screw 2 demonstrated the most consistent stability across all tested SSRO techniques.
Area of Science:
- Orthognathic surgery
- Biomechanical analysis
- Craniofacial reconstruction
Background:
- Sagittal split osteotomy (SSO) is a common procedure in orthognathic surgery.
- Different SSO designs exist, potentially influencing surgical outcomes and hardware stability.
- Understanding screw deformation under load is crucial for optimizing fixation and minimizing complications.
Purpose of the Study:
- To compare screw deformation under vertical load across three distinct sagittal split osteotomy (SSO) designs: Epker, Wolford, and Wyatt.
- To evaluate the biomechanical stability and stress distribution associated with each SSO technique.
- To identify optimal fixation strategies for enhanced surgical outcomes.
Main Methods:
- Thirty polyurethane hemimandibles were divided into three groups (n=10) based on SSO design (Epker, Wolford, Wyatt).
- Standardized fixation with three titanium screws in an inverted L configuration was applied to all specimens.
- Strain gauges measured screw deformation during vertical loading to failure; peak load and deformation were recorded and analyzed using the Kruskal-Wallis test.
Main Results:
- The Wolford design (Group II) exhibited the highest mean load resistance and most uniform stress distribution, indicating superior stability.
- The Epker design (Group I) showed stress concentration at screw 1, while the Wyatt design (Group III) demonstrated lower load resistance, increased variability, and earlier failure, with stress at screw 3.
- Screw 2 consistently showed the lowest deformation and highest stability across all tested SSO designs.
Conclusions:
- Sagittal split osteotomy design significantly impacts force distribution and screw stability.
- Techniques preserving proximal segment thickness, such as the Wolford and Epker designs, enhance load dissipation.
- The Wyatt design modification, with inverted-L fixation, exhibited reduced stability, highlighting the importance of surgical planning for optimal fixation and reduced failure risk.
