Computed tomography Hounsfield unit–based prediction of pedicle screw loosening after surgery for degenerative lumbar spine disease

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>The authors investigated the relation between Hounsfield unit (HU) values measured on CT and the risk of pedicle screw loosening in patients who underwent lumbar pedicle screw fixation for degenerative lumbar spine disease.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>Patients who were treated with lumbar pedicle screw fixation between July 2011 and December 2015 at the authors’ department were reviewed. Age, sex, BMI, smoking and diabetes histories, range of fixation, and fusion method were recorded as the basic patient information. The HU values for lumbar bone mineral density (BMD) for the L1, L2, L3, and L4 vertebra were measured on CT scans. Logistic regression analysis was used to identify the independent influencing factors of pedicle screw loosening.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>A total of 503 patients were included in the final analysis. The pedicle screw loosening rate at the 12-month follow-up was 30.0% (151 of 503 patients). There were no significant differences in sex, BMI, or histories of smoking and diabetes between the patients with (loosening group) and those without (nonloosening group) screw loosening (p &gt; 0.05). The mean HU value of L1–4 was lower in the loosening group than the nonloosening group (106.3 ± 33.9 vs 132.6 ± 42.9, p &lt; 0.001). In logistic regression analysis, being male (OR 2.065; 95% CI 1.242–3.433), HU value (OR 0.977; 95% CI 0.970–0.985), length of fixation (OR 3.616; 95% CI 2.617–4.996), and fixation to S1 (OR 1.699; 95% CI 1.039–2.777) were the independent influencing factors for screw loosening.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>HU value measured on CT was an independent predictor for pedicle screw loosening, and lower HU value was significantly correlated with higher risk of screw loosening.</jats:p></jats:sec>

Diagnostic, Surgical, and Technical Considerations for Lumbar Interbody Fusion in Patients with Osteopenia and Osteoporosis: A Systematic Review

“…A retrospective review by Zou et al [ 10 ] studied the relationship between preoperative HU values (axial CT) and the 1-year risk of pedicle screw loosening in 503 patients that underwent lumbar pedicle screw fixation (posterolateral lumbar fusion (PLF) or posterior lumbar interbody fusion (PLIF)) due to degenerative lumbar spine disease. The mean age was 61.2 years, and 315 (62.6%) of patients were female.…”

“…Another study correlated HU with successful fusion rates at least 12 weeks postoperatively, suggesting higher BMD may lead to an increased likelihood of fusion at 12 weeks [ 9 ]. Zou et al determined that a low HU value was significantly correlated as an independent factor for postoperative screw loosening in patients 1 year after lumber pedicle screw fixation for the treatment of degenerative lumbar spine disease; however, the authors also suggested other potential influencing factors, such as screw size, postoperative sagittal alignment, and other spinopelvic parameters [ 10 ]. These studies suggested that HU may be useful in both presurgical planning and postoperative outcome prediction with respect to fusion rates and screw fixation in osteopenic and osteoporotic patients undergoing LIF.…”

The association between lower Hounsfield units of the upper instrumented vertebra and proximal junctional kyphosis in adult spinal deformity surgery with a minimum 2-year follow-up

“…3,4,17 Recent studies have shown that HU values measured on preoperative CT are independent predictors of implant loosening, and lower HU values are significantly correlated with a higher risk of pedicle screw loosening after lumbar fusion. [34][35][36] Schwaiger et al demonstrated that HU values on CT adequately differentiated patients with and without osteoporotic fractures, and they showed that HU values could predict pedicle screw loosening after fusion. 36 However, previous studies have focused on the lumbar spine, establishing thresholds of 135 HU for osteopenic spines, 120 HU for the risk of pedicle screw loosening, 110 HU for osteoporotic spines, and 90 HU for the risk of vertebral body fracture.…”

The Role of Prophylactic Vertebroplasty at UIV+1 and Cement-augmented Fenestrated Pedicle Screw for Prevention of PJK/PJF&nbsp; in Patients With Osteoporosis: A Propensity Score–matched Analysis

“…PJF, which may require revision surgery for proximal extension of fusion, was de ned as vertebral fracture of UIV or (and) UIV + 1, pull-out of instrumentation at UIV, and/or sagittal subluxation 3 . Pedicle screw loosening was de ned as the clear zone around the pedicle screw exceeded 1 mm on anteroposterior and lateral radiographs 16 .…”