A Surgical Method for Determining Proper Screw Length in ACDF

Area of Science:

• Neurosurgery
• Orthopedic Surgery
• Spinal Surgery

Background:

• Accurate screw length is crucial in anterior cervical discectomy and fusion (ACDF) for optimal fixation strength.
• Exceeding the safe depth risks posterior cortical wall violation, compromising surgical outcomes.
• Current methods for determining screw length may lack precision, potentially leading to suboptimal purchase depth.

Purpose of the Study:

• To introduce and evaluate a novel surgical technique for precise screw length determination in ACDF.
• To utilize the distractor pin as a reliable intraoperative reference for screw sizing.
• To enhance screw purchase depth while preventing posterior cortical wall penetration.

Main Methods:

• A prospective study involving 81 adult patients undergoing ACDF with anterior cervical plating.
• Patients were divided into two groups: Group A (42 patients) using the distractor pin reference, and Group B (39 patients) as the control.
• Intraoperative lateral X-rays were used to measure the ratio of distractor pin length to the anteroposterior (A-P) diameter of the vertebral body.

Main Results:

• Group A demonstrated a smaller average distance from screw tip to posterior wall (3.0±1.4mm) compared to Group B (4.1±2.3mm).
• The ratio of screw length to body sagittal diameter was significantly higher in Group A (86.2±5.7%) versus Group B (80.8±9.0%).
• 90% of patients in Group A achieved a screw length to body sagittal diameter ratio greater than 4/5, with no posterior cortical wall violations.

Conclusions:

• The described method provides a reliable and effective means for determining appropriate screw length during ACDF.
• Utilizing the distractor pin-to-vertebral body diameter ratio facilitates deeper screw purchase.
• This technique enhances screw fixation strength and safety by avoiding posterior cortical wall breach.