Comparative effectiveness of Hounsfield unit, MRI-based bone quality, dual-energy X-ray absorptiometry T -score, and quantitative computed tomography-measured bone mineral density in predicting cage subsidence and screw loosening post-spinal surgery.

OBJECTIVE

Cage subsidence and screw loosening are the frequent complications following spinal fusion, and identifying the patients at high risk was of critical importance. This study was performed to investigate the effectiveness of the Hounsfield unit (HU), dual-energy X-ray absorptiometry (DEXA) T-scores, quantitative computed tomography (QCT)-measured bone mineral density (BMD), and MRI-based bone quality (BQ) including vertebral BQ (VBQ), endplate BQ (EBQ), and pedicle BQ (PBQ), in predicting the cage subsidence and screw loosening.

METHODS

A comprehensive search was conducted across PubMed, Embase, Web of Science, and Cochrane to identify eligible studies. Studies evaluating the use of HU values, VBQ scores, DEXA T-scores, QCT-assessed BMD, EBQ scores, or PBQ scores in relation to the incidence of cage subsidence or screw loosening were included.

RESULTS

The pooled results revealed significant differences in HU values (MD, -62.78; 95% CI, -78.35 to -47.20; P < 0.001), VBQ scores (MD, 0.78; 95% CI, 0.51 to 1.05; P < 0.001), DEXA T-scores (MD, -0.57; 95% CI, -1.01 to -0.14; P = 0.01), and EBQ scores (MD, 0.75; 95% CI, 0.46 to 1.04; P < 0.001) between the cervical subsidence and non-subsidence groups. Similarly, notable disparities were observed in HU values (MD, -30.61; 95% CI, -34.27 to -26.94; P < 0.001), VBQ scores (MD, 0.53; 95% CI, 0.34 to 0.73; P < 0.001), DEXA T-scores (MD, -0.80; 95% CI, -0.92 to -0.67; P < 0.001), QCT-assessed BMD (MD, -24.94; 95% CI, -39.68 to -10.21; P < 0.001), and EBQ scores (MD, 0.67; 95% CI, 0.36 to 0.99; P <0.001) between the lumbar subsidence and non-subsidence groups. Additionally, there were significant distinctions in HU values (MD, -29.28; 95% CI, -34.33 to -24.23; P < 0.001), VBQ scores (MD, 0.62; 95% CI, 0.38 to 0.86; P < 0.001), DEXA T-scores (MD, -0.35; 95% CI, -0.53 to -0.16; P < 0.001), QCT-assessed BMD (MD, -18.99; 95% CI, -21.69 to -16.29; P < 0.001), and PBQ scores (MD, 0.57; 95% CI, 0.53 to 0.62; P < 0.001) between the screw loosening and non-loosening groups. Furthermore, the area under the curve (AUCs) of HU values and VBQ scores for cervical cage subsidence were 0.90 (95% CI, 0.87 to 0.92) and 0.86 (95% CI, 0.83 to 0.89), respectively; the AUCs of HU values, VBQ scores, DEXA T-scores, and EBQ scores for lumbar cage subsidence were 0.82 (95% CI, 0.78 to 0.85), 0.86 (95% CI, 0.82 to 0.89), 0.86 (95% CI, 0.83 to 0.89), and 0.80 (95% CI, 0.76 to 0.83), respectively; the AUCs of HU values and VBQ scores for screw loosening were 0.73 (95% CI, 0.69 to 0.77) and 0.80 (95% CI, 0.76 to 0.83), respectively.

CONCLUSION

The HU values, VBQ scores, DEXA T-scores, and QCT-measured BMD demonstrated significant associations with cage subsidence and screw loosening. Specifically, HU values and VBQ scores exhibited high predictive efficacy for cervical cage subsidence; VBQ scores and DEXA T-scores demonstrated strong predictive capabilities for lumbar cage subsidence; VBQ scores, exceeding HU values, were highly effective in predicting screw loosening. The combinations of different imaging techniques, including the HU values and VBQ scores for cervical cage subsidence, VBQ scores and DEXA T-scores for lumbar cage subsidence, and VBQ scores and HU values for screw loosening, optimized preoperative assessment and postoperative rehabilitation in patients receiving spinal fusion.