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An in vitro comparison of an adjustable bone fixation system
Joseph E Van Sickels1, Gilman P Peterson, Stephen Holms
1Oral and Maxillofacial Surgery, University of Kentucky, College of Dentistry, D512 Chandler Medical Center, Lexington, KY 40536-0297, USA. vansick@email.uky.edu
Summary
An adjustable sagittal split plate provides torsional resistance comparable to traditional screw fixation for mandibular advancements. However, additional bicortical screws are needed for comparable vertical load resistance.
Area of Science:
- Orthognathic surgery
- Biomechanical analysis
- Craniofacial reconstruction
Background:
- Bilateral sagittal split osteotomy (BSSO) is a common procedure for mandibular advancement.
- Fixation methods for BSSO aim to provide stability and promote bone healing.
- Adjustable plating systems offer potential advantages in contouring and screw placement flexibility.
Purpose of the Study:
- To biomechanically compare an adjustable plating system with variations against a traditional inverted-L screw pattern for BSSO fixation.
- To evaluate the mechanical stability of different fixation configurations under vertical and torsional loads.
Main Methods:
- Sixty synthetic polyurethane mandibles underwent a 7-mm bilateral sagittal split osteotomy.
- Fixation groups included an inverted-L screw pattern and an adjustable plate with 0-3 additional bicortical screws.
- Specimens were subjected to vertical loads at the incisal edge and torsional loads at the molar region using a servohydraulic mechanical testing unit.
Main Results:
- The adjustable plate (slide 0) showed comparable torsional resistance to the inverted-L screw pattern.
- No significant difference in torsional resistance was found between adjustable plate configurations (slide 1-3) and the inverted-L pattern.
- For vertical loading at the incisal edge, adjustable plate configurations with fewer than 3 additional screws (slide 0-2) were significantly less resistant than the inverted-L pattern.
Conclusions:
- A 4-hole adjustable sagittal split plate alone offers sufficient torsional resistance for 7-mm mandibular advancements, comparable to 3 bicortical screws in an inverted-L pattern.
- To achieve comparable resistance to vertical loads at the incisal edge, additional bicortical screws are necessary when using the adjustable plating system.