Temporal Shape Changes of Pedicle Screw-rod Constructs After Lumbar Interbody Fusion

Area of Science:

• Spinal surgery
• Orthopedic biomechanics
• Medical imaging analysis

Background:

• Screw-rod constructs are used in short-segment lumbar fusion.
• The temporal changes in construct shape and their clinical relevance are not well understood.

Purpose of the Study:

• To analyze the shape evolution of screw-rod constructs after lumbar interbody fusion.
• To investigate the relationship between construct shape changes and clinical characteristics.

Main Methods:

• Retrospective analysis of 108 patients undergoing single-level lumbar interbody fusion.
• Three-dimensional (3D) CT imaging used to quantify construct shape changes over time.
• Comparison of shape change values across different postoperative time points (≤1, 2-3, 4-6, 7-12, ≥13 months).

Main Results:

• Significant differences in screw-rod construct shape change were observed across time categories (P <0.001).
• Most shape changes occurred within the first 6 months postoperatively.
• No significant correlations were found between shape change values and clinical factors like age, bone density, or fusion status.

Conclusions:

• Screw-rod construct shape changes after short-segment lumbar interbody fusion stabilize by 6 months post-surgery.
• The observed temporal shape changes do not appear to be significantly related to clinical characteristics.