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Motion observed across maxillary continuity defects stabilized with plates and screws
G F Funk1, R B Stanley, H A McKellop
1Department of Otolaryngology-Head and Neck Surgery, University of Southern California School of Medicine, Los Angeles.
Archives of Otolaryngology--Head & Neck Surgery
|February 1, 1994
Summary
Internal fixation devices (plates and screws) show micromotion in maxillary defects, challenging the term "rigid." This bone movement could lead to permanent deformation, impacting treatment outcomes.
Area of Science:
- Oral and Maxillofacial Surgery
- Biomechanical Engineering
- Orthodontic Research
Background:
- Maxillary continuity defects often require internal fixation with plates and screws.
- The stability of these fixation devices under functional loading is critical for successful bone healing.
- Current terminology may overestimate the rigidity of plate and screw fixation.
Purpose of the Study:
- To investigate the stability of internal fixation devices under functional loading in maxillary defects.
- To quantify micromotion at the osteotomy site.
- To evaluate the predictability of deformation based on screw stability.
Main Methods:
- Fresh cadaver skulls were used as a biomechanical model.
- LeFort I osteotomies were created to simulate maxillary continuity defects.
- Micromotion at the osteotomy site was recorded under functional loading conditions.
Main Results:
- Micromotion was consistently observed at the LeFort I osteotomy sites, even with seemingly stable fixation.
- Deformation was primarily elastic in nature.
- The amount of deformation was predictable based on the average stability of screws within each plate.
Conclusions:
- Plate and screw fixation for maxillary continuity defects is not entirely rigid.
- Elastic micromotion may lead to permanent bone deformation through resorption and remodeling.
- The term "rigid" should be used cautiously when describing this type of fixation.