Radiographic spine adipose index: an independent risk factor for deep surgical site infection after posterior instrumented lumbar fusion

Subcutaneous Lumbar Spine Index (SLSI) as a Risk Factor for Surgical Site Infection After Lumbar Fusion Surgery: A Retrospective Matched Case-Control Study

STUDY DESIGN

A retrospective matched case-control study.

OBJECTIVE

This study aims to investigate the value of Subcutaneous Lumbar Spine Index (SLSI) as a predictor of early surgical site infection (SSI) after lumbar intervertebral fusion surgery.

METHODS

A retrospective case-control study was performed on patients who underwent transforaminal lumbar interbody fusion (TLIF) from January 1, 2014 to December 31, 2019 in a single institution. Cases were defined as those who developed early SSI according to the US Center for Disease Control and Prevention criteria, and controls were matched from those patients without early SSI using the following matched criteria: gender, age, time of surgery and diabetes. Subcutaneous fat thickness (SFT) and SLSI were measured on preoperative MRI mid-sagittal T2 weighted images.

RESULTS

A total of 3615 patients who underwent TLIF were enrolled in this study. Thirty-three patients were included in early SSI, and sixty-six patients were selected as matched controls. Univariate analysis indicated that fusion levels (P = .007), operation time (P = .022), obesity (P = .013), SFT (P = .002) and SLSI (P = .001) were significantly associated with early SSI. Multiple logistic regression analysis revealed that multilevel fusion levels (P = .021), obesity (P = .035), a large SFT (P = .026) and a high SLSI (P = .012) were independent risk factors. Body mass index (BMI) and SLSI were moderately correlated (r2 = .55). ROC curve demonstrated that SLSI was more sensitive than SFT to predict the early SSI.

CONCLUSION

SLSI is a novel radiological risk factor for early SSI development and is a better indicator than SFT to predict early SSI risk after lumbar intervertebral fusion.

Abdominal Fat is a Reliable Indicator of Lumbar Intervertebral Disc Degeneration than Body Mass Index

OBJECTIVE

The objective of this study was to determine whether abdominal fat status correlates with low back pain (LBP) and lumbar intervertebral disc degeneration (IVDD) and to identify a new anthropometric index to predict the likelihood of developing LBP.

METHODS

Patients with chronic low back pain admitted to the Affiliated Hospital of Southwest Medical University from June 2022 to May 2023 were collected as the experimental group. Volunteers without LBP from June 2022 to May 2023 were also recruited as the control group. They underwent lumbar spine magnetic resonance imaging and had their body mass index (BMI) measured. Abdominal parameters were measured on T2-weighted median sagittal magnetic resonance imaging at the L3/4 level: abdominal diameter, sagittal abdominal diameter (SAD), and subcutaneous abdominal fat thickness (SAFT). Each lumbar IVDD was assessed using the Pfirrmann grading system. The differences in abdominal parameters and BMI between the experimental and control groups were compared, and the correlations between abdominal parameters, BMI, LBP, and IVDD were analyzed.

RESULTS

Abdominal diameter, SAD, and SAFT had moderate-to-strong correlations with BMI. SAD was significantly associated with severe IVDD at L4-L5 and L5-S1 levels with odds ratio of 3.201 (95% confidence interval [CI]: 1.850-5.539, P < 0.001) and 1.596 (95% CI: 1.072-2.378, P = 0.021), respectively. BMI had no significant association with severe IVDD. In women, SAFT and BMI were significantly correlated with LBP; in men, only SAFT was significantly correlated with LBP. Appropriate cutoff values for men and women were 1.52 cm (area under the curve = 0.702, 95% CI: 0.615-0.789, P < 0.001) and 1.97 cm (area under the curve = 0.740, 95% CI: 0.662-0.818, P < 0.001), respectively. Men and women with SAFT of >1.52 cm and >1.97 cm, respectively, had significantly higher rates of LBP.

CONCLUSIONS

SAD could predict severe IVDD better than BMI. SAFT is a better predictor of LBP than BMI, especially in men, and reliably distinguished patients with LBP from asymptomatic subjects with reliable cutoff values for men and women.

Role of Pre-Operative Nutrition Status on Surgical Site Infection After Posterior Lumbar Interbody Fusion: A Retrospective Study

Background: A retrospective case-control study to determine the role of pre-operative systemic and local nutritional factors on patients developing a surgical site infection (SSI) after posterior lumbar interbody fusion (PLIF). Surgical site infection after PLIF remains a substantial cause of morbidity. The literature demonstrates the prognosis of surgical patients is associated with pre-operative nutritional status that not only includes systemic nutritional factors, such as prognostic nutritional index (PNI), body mass index (BMI), and serum albumin, but also local nutritional factors, such as subcutaneous fat thickness at the surgical site, including absolute fat thickness and relative fat thickness. However, the role of pre-operative nutrition status in SSI after PLIF surgery remains unclear. Patients and Method: A retrospective review was performed on a consecutive cohort of 766 consecutive adult patients who underwent PLIF surgery for lumbar degenerative conditions between 2020 and 2021 at Second Xiangya Hospital. Previously identified risk factors as well as systemic and local nutritional factors nutritional factors were collected. Results: Among the 766 patients, 38 had post-operative SSI including 15 superficial SSI and 23 deep SSI. Univariable analysis showed that body weight, BMI, PNI, serum albumin, and relative fat thickness differed between the SSI and non-SSI groups. Multivariable logistic regression analysis showed that pre-operative PNI and relative fat thickness were independently associated with SSI after PLIF surgery. Conclusions: Lower pre-operative PNI and higher relative fat thickness are independent risk factors for developing deep SSI after PLIF.

The role of spine adipose index in predicting the risk for septic spondylodiscitis after lumbar percutaneous laser disc decompression

The aim. To analyze the role of the spine adipose index (SAI) in predicting the risk of septic spondylodiscitis after lumbar percutaneous laser disk decompression (PLDD).

Material and methods. A retrospective observational single-center study was performed. Various clinical and instrumental parameters have been studied, including the spine adipose index, which are potential risk factors for the development of postprocedural septic spondylodiscitis.

Results. The study included 219  patients who underwent PLDD for degenerative lumbar disk disease. The average period of postoperative observation was  30.8  ±  13.3  months. Signs of septic spondylodiscitis were detected in 5 (2.28%) cases. Multivariate analysis showed that III degree of anesthesiological risk by the American Society of Anesthesiologists (ASA) scale (p = 0.021), a high value of body mass index (more than 25 kg/m2) (p = 0.043) and a high value of SAI (over 0.7) (p = 0.037) are statistically significantly associated with the development of septic spondylodiscitis in patients who underwent lumbar PLDD.

Conclusion. The value of SAI is statistically significantly associated with the development of spondylodiscitis in patients who underwent PLDD for degenerative lumbar disk disease.