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Does Screw Number of Zero-profile Implants in Fusion Segment Influence Intervertebral Stability?
Zihan Peng1, Yuxiao Deng1, Xiaqing Sheng1
1Department of Orthopedics, Orthopedic Research Institute, West China Hospital, Sichuan University, Chengdu, China.
Orthopaedic Surgery
|June 19, 2024
Summary
Zero-profile implants with two or four screws offer similar spinal fusion outcomes. However, two-screw implants show increased subsidence, making four-screw options preferable for high-risk patients.
Area of Science:
- Spine surgery
- Orthopedic implants
- Fusion techniques
Background:
- Zero-profile implants are used in hybrid surgery for spinal fusion.
- The choice between two-screw and four-screw zero-profile implants is unclear due to limited comparative data.
- Patient-specific implant selection is crucial for optimal outcomes.
Purpose of the Study:
- To compare the postoperative subsidence, motion stabilization, and clinical outcomes of two-screw versus four-screw zero-profile implants in hybrid spinal fusion.
- To provide evidence-based recommendations for selecting the most appropriate implant in fusion surgery.
Main Methods:
- Retrospective study of 173 patients undergoing hybrid surgery between February 2014 and March 2022.
- Patients were divided into two groups: 122 receiving a four-screw implant and 51 receiving a two-screw implant.
- Statistical analysis included the Wilcoxon rank sum test, t-tests/ANOVA, and stepwise multivariate logistic regression to assess patient-specific, radiographic, and clinical factors.
Main Results:
- No significant differences were found in immediate, middle, or long-term stability and fusion rates between the two and four-screw groups (p > 0.05).
- The two-screw group exhibited significantly higher FSU height subsidence at 3, 6, and 12 months postoperatively (p < 0.05).
- Both groups demonstrated significant clinical improvements at the final follow-up.
Conclusions:
- Two-screw and four-screw zero-profile implants yield comparable spinal stability, fusion rates, and clinical outcomes.
- The two-screw implant is associated with inferior subsidence prevention compared to the four-screw implant.
- While the two-screw implant is a viable option for most patients due to ease of use, the four-screw implant is recommended for individuals at high risk of subsidence.
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