Can Preoperative Hounsfield Unit Measurement Help Predict Mechanical Failure in Metastatic Spinal Tumor Surgery?

Area of Science:

• Orthopedics
• Neurosurgery
• Oncology

Background:

• Metastatic spinal tumors often require surgical intervention.
• Spinal instrumentation without fusion is a technique used in these cases.
• Mechanical failure of implants is a significant complication.

Purpose of the Study:

• To identify risk factors for mechanical failure in spinal instrumentation without fusion for metastatic spinal tumors.
• To evaluate the association between bone density and implant failure.

Main Methods:

• Retrospective analysis of 220 patients undergoing spinal instrumentation without fusion.
• Propensity score matching to create comparable failure and non-failure groups (24 vs. 72 patients).
• Logistic regression and Kaplan-Meier survival analyses to identify predictors of mechanical failure.

Main Results:

• Lower Hounsfield unit (HU) values at the lowest instrumented vertebra (LIV) were the sole independent predictor of implant failure (p=0.037).
• A LIV HU cutoff of 127.273 predicted mechanical failure with 59.1% sensitivity and 73.4% specificity.
• Patients with LIV HU < 127.273 showed significantly lower survival rates (p=0.0057).

Conclusions:

• Preoperative LIV bone density, measured in Hounsfield units (HU), is a critical factor in predicting mechanical failure.
• Spinal instrumentation without fusion in patients with low LIV HU values (<127.273) carries a higher risk of mechanical failure.
• Cement-augmented screws may be a beneficial alternative or adjunct for patients with compromised bone density.