Characteristics of the DXA Measurements in Patients Undergoing Lumbar Fusion for Lumbar Degenerative Diseases: A Retrospective Analysis of Over 1000 Patients

The influence of osteoporosis on mechanical complications in lumbar fusion surgery: a systematic review

Background

Adults undergoing spine surgery often have underlying osteoporosis, which may be a risk factor for postoperative complications. Although these associations have been described, osteoporosis remains profoundly underdiagnosed and undertreated in the spine surgery population. A thorough, comprehensive systematic review summarizing the relationships between bone mineral density (BMD) and specific complications of lumbar fusion surgery could be a valuable resource for raising awareness and supporting clinical practice changes.

Methods

PubMed, Embase, and Web of Science databases were searched for original clinical research articles reporting on BMD, or surrogate measure, as a predictor of complications in adults undergoing elective lumbar fusion for degenerative disease or deformity. Endpoints included cage subsidence, screw loosening, pseudarthrosis, vertebral fracture, junctional complications, and reoperation.

Results

A total of 71 studies comprising 12,278 patients were included. Overall, considerable heterogeneity in study populations, methods of bone health assessment, and definition and evaluation of clinical endpoints precluded meta-analysis. Nevertheless, low BMD was associated with higher rates of implant failures like cage subsidence and screw loosening, which were often diagnosed with concomitant pseudarthrosis. Osteoporosis was also a significant risk factor for proximal junctional kyphosis, particularly due to fracture. Many studies found surgical site-specific BMD to best predict focal complications. Functional outcomes were inconsistently addressed.

Conclusions

Our findings suggest osteoporosis is a significant risk factor for mechanical complications of lumbar fusion. These results emphasize the importance of preoperative osteoporosis screening, which allows for medical and surgical optimization of high-risk patients. This review also highlights current practical challenges facing bone health evaluation in patients undergoing elective surgery. Future prospective studies using standardized methods are necessary to strengthen existing evidence, identify optimal predictive thresholds, and establish specialty-specific practice guidelines. In the meantime, an awareness of the surgical implications of osteoporosis and utility of preoperative screening can provide for more informed, effective patient care.

Skeletal Status in Patients Scheduled for Elective Lumbar Spine Surgery: Comparison of Discectomy, Decompression, Fusion, and Revision

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVES

To investigate and compare the prevalence of low bone mineral density (BMD) and abnormal laboratory bone metabolism parameters in patients undergoing elective primary discectomy, decompression, and fusion and to outline possible differences in these parameters between patients undergoing revision for skeletal vs non-skeletal complications.

METHODS

We retrospectively evaluated BMD measurements by dual-energy x-ray absorptiometry (DXA) in 389 consecutive patients scheduled for elective lumbar spine surgery. Next to demographic characteristics, laboratory bone metabolism parameters were assessed. Group comparisons were performed between primary discectomy, decompression, and fusion. In patients scheduled for revision surgery after fusion, potential differences in the skeletal status between those with skeletal vs non-skeletal complications were analyzed.

RESULTS

Osteoporosis by T-score was detected in 6.7%, 11.0% and 14.7% of the patients undergoing discectomy, decompression and fusion, respectively. While vitamin D deficiency (67.6%) and hyperparathyroidism (16.4%) were frequently detected, no differences in laboratory bone metabolism markers could be found between the groups. Female sex (P<.001), higher age (P=.01) and lower BMI (P<.001) were associated with lower BMD. In the cohort of patients undergoing revision surgery due to complications after fusion, those with skeletal complications did not differ in BMD or bone metabolism from those with non-skeletal complications.

CONCLUSIONS

Osteoporosis represents a relevant comorbidity in patients scheduled for elective spine surgery, which is why DXA should be routinely performed in these patients. However, DXA may provide limited information in identifying patients at increased risk for skeletal complications after fusion.

Evaluation and analysis of surgical treatment for single-level or multi-level lumbar degenerative disease based on radiography

Background

Radiography has a low level of radiation exposure while providing valuable information. Due to its cost effectiveness and widespread availability, the preoperative radiographic imaging examination is a valuable approach for assessing patients with spinal disease. This study aimed to examine the influence of preoperative X-ray evaluation on the surgical treatment of patients with single- or multi-level lumbar degenerative disease (LDD).

Methods

A retrospective cohort analysis was conducted of 172 patients diagnosed with LDD who underwent transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF) surgery between December 2021 and February 2023 at the Shanghai Changzheng Hospital. Various parameters were measured on preoperative radiographs, including the iliac crest height, median iliac angle (MIA), lumbar lordosis (LL), intervertebral facet joint degeneration, lumbosacral angle (LSA), intervertebral foramen height (IFH), and surgical segment. The surgical treatment was evaluated based on the operative time, intraoperative blood loss, and postoperative complications. A correlation analysis and independent sample t-tests were used to assess the relationship between preoperative radiographic variables and surgical treatments. Further, a multivariate linear regression analysis was employed to identify the risk factors affecting the clinical outcomes.

Results

The correlation analysis and t-test results showed that the MIA, height of the iliac crest, intervertebral facet joint degeneration, and surgical segment were significantly correlated with the surgical treatments (P<0.05). Specifically, the height of the iliac crest, intervertebral facet joint degeneration, and surgical segment were positively correlated with the surgical treatments. Conversely, the MIA was negatively correlated with the surgical treatments. However, no significant differences were observed between the IFH, LSA, and LL in relation to posterior lumbar surgery (P>0.05). The multiple linear regression analysis showed that the height of the iliac crest, MIA, intervertebral facet joint degeneration, and surgical segment were independent factors affecting the surgical treatments of patients with single- or multi-level LDD. These findings highlight the importance of considering these factors when planning and performing lumbar surgery.

Conclusions

The measurements taken from radiographs, including the height of the iliac crest, MIA, intervertebral facet joint degeneration, and surgical segment, demonstrate potential influences on the treatment of single- and multi-level lumbar spine surgery. These variables can be captured in plain film imaging and can provide valuable insights into the surgical procedure and offer guidance for the operation. By analyzing these radiographic measurements, surgeons can gain a better understanding of a patient's condition and tailor the surgical approach accordingly, thus optimizing the outcomes of the surgery.

Bone microstructure and volumetric bone mineral density in patients with global sagittal malalignment

PURPOSE

Sagittal spinal malalignment often leads to surgical realignment, which is associated with major complications. Low bone mineral density (BMD) and impaired bone microstructure are risk factors for instrumentation failure. This study aims to demonstrate differences in volumetric BMD and bone microstructure between normal and pathological sagittal alignment and to determine the relationships among vBMD, microstructure, sagittal spinal and spinopelvic alignment.

METHODS

A retrospective, cross-sectional study of patients who underwent lumbar fusion for degeneration was conducted. The vBMD of the lumbar spine was assessed by quantitative computed tomography. Bone biopsies were evaluated using microcomputed tomography (μCT). C7-S1 sagittal vertical axis (SVA; ≥ 50 mm malalignment) and spinopelvic alignment were measured. Univariate and multivariable linear regression analysis evaluated associations among the alignment, vBMD and μCT parameters.

RESULTS

A total of 172 patients (55.8% female, 63.3 years, BMI 29.7 kg/m2, 43.0% with malalignment) including N = 106 bone biopsies were analyzed. The vBMD at levels L1, L2, L3 and L4 and the trabecular bone (BV) and total volume (TV) were significantly lower in the malalignment group. SVA was significantly correlated with vBMD at L1-L4 (ρ = -0.300, p < 0.001), BV (ρ = - 0.319, p = 0.006) and TV (ρ = - 0.276, p = 0.018). Significant associations were found between PT and L1-L4 vBMD (ρ = - 0.171, p = 0.029), PT and trabecular number (ρ = - 0.249, p = 0.032), PT and trabecular separation (ρ = 0.291, p = 0.012), and LL and trabecular thickness (ρ = 0.240, p = 0.017). In the multivariable analysis, a higher SVA was associated with lower vBMD (β = - 0.269; p = 0.002).

CONCLUSION

Sagittal malalignment is associated with lower lumbar vBMD and trabecular microstructure. Lumbar vBMD was significantly lower in patients with malalignment. These findings warrant attention, as malalignment patients may be at a higher risk of surgery-related complications due to impaired bone. Standardized preoperative assessment of vBMD may be advisable.

Safety and efficacy of unilateral and bilateral pedicle screw fixation for lumbar degenerative diseases by transforaminal lumbar interbody fusion: An updated systematic review and meta-analysis

Background

The purpose of this study was to compare the safety and efficacy of unilateral vs. bilateral pedicle screw fixation (BPSF) for lumbar degenerative diseases.

Methods

Electronic databases including PubMed, Web of science, the Cochrane Library, Scopus, MEDLINE, EMBASE, EBSCO were searched by computer. The deadline was set for June 1, 2022. This study included all high-quality randomized controlled trials (RCTs), prospective clinical controlled studies (PRO), and retrospective studies (Retro) that compared unilateral and bilateral pedicle screw fixation in the treatment of lumbar degenerative diseases. Revman5.3 software was used for meta-analysis after two researchers independently screened the literature, extracted data, and assessed the risk of bias in the study.

Results

Fourteen studies with a total of 1,086 patients were included. Compared with BPSF, unilateral pedicle screw fixation (UPSF) has shorter operation time and hospital time, and less blood loss and operation cost, operation time [SMD = −1.75, 95% CI (−2.46 to −1.03), P < 0.00001], hospital time [SMD = −1.10, 95% CI (−1.97 to −0.22), P = 0.01], Blood loss [SMD = −1.62, 95% CI (−2.42 to −0.82), P < 0.0001], operation cost [SMD = −14.03, 95% CI (−20.08 to −7.98), P < 0.00001], the ODI after bilateral pedicle screw fixation was lower, and the degree of lumbar dysfunction was lighter, [SMD = 0.19, 95% CI (0.05–0.33), P = 0.007], better fusion effect, fusion rate [RR=0.95, 95% CI (0.91–1.00), P = 0.04]. VAS-Low back pain [SMD = 0.07, 95% CI (−0.07–0.20), P = 0.35], VAS-Leg pain [SMD = 0.18, 95% CI (−0.00–0.36), P = 0.05], SF-36 [SMD = 0.00, 95% CI (−0.30–0.30), P = 1.00], complications rate [RR = 0.94, 95% CI (0.9154–1.63), P = 0.82], the overall difference was not statistically significant.

Conclusions

Currently limited evidence suggests that UPSF significantly reduces blood loss, significantly shortens the operative time and hospital stay, and reduces blood loss and costs. After BPSF, the ODI was lower, the degree of lumbar spine dysfunction was lower, and the fusion rate was significantly higher. The VAS, SF-36, and complications scores of the two groups were comparable, and there was no significant clinical difference.