Quantitative CT for Preoperative Assessment of Lumbar Degenerative Spondylolisthesis: The Unique Impact of L4 Bone Mineral Density on Single-Level Disease

Differences in imaging and clinical characteristics are associated with higher rates of decompression-fusion versus decompression-alone in women compared to men for lumbar degenerative spondylolisthesis

PURPOSE

The goals were to ascertain if differences in imaging/clinical characteristics between women and men were associated with differences in fusion for lumbar degenerative spondylolisthesis.

METHODS

Patients had preoperative standing radiographs, CT scans, and intraoperative fluoroscopic images. Symptoms and comorbidity were obtained from patients; procedure (fusion-surgery or decompression-alone) was obtained from intraoperative records. With fusion surgery as the dependent variable, men and women were compared in multivariable logistic regression models with clinical/imaging characteristics as independent variables. The sample was dichotomized, and analyses were repeated with separate models for men and women.

RESULTS

For 380 patients (mean age 67, 61% women), women had greater translation, listhesis angle, lordosis, and pelvic incidence, and less diastasis and disc height (all p ≤ 0.03). The rate of fusion was higher for women (78% vs. 65%; OR 1.9, p = 0.008). Clinical/imaging variables were associated with fusion in separate models for men and women. Among women, in the final multivariable model, less comorbidity (OR 0.5, p = 0.05), greater diastasis (OR 1.6, p = 0.03), and less anterior disc height (OR 0.8, p = 0.0007) were associated with fusion. Among men, in the final multivariable model, opioid use (OR 4.1, p = 0.02), greater translation (OR 1.4, p = 0.0003), and greater diastasis (OR 2.4, p = 0.0002) were associated with fusion.

CONCLUSIONS

There were differences in imaging characteristics between men and women, and women were more likely to undergo fusion. Differences in fusion within groups indicate that decisions for fusion were based on composite assessments of clinical and imaging characteristics that varied between men and women.

Instability Missed by Flexion-Extension Radiographs Subsequently Identified by Alternate Imaging in L4-L5 Lumbar Degenerative Spondylolisthesis

STUDY DESIGN

Cross-sectional preoperative and intraoperative imaging study of L4-L5 lumbar degenerative spondylolisthesis (LDS).

OBJECTIVE

To determine if alternate imaging modalities would identify LDS instability that did not meet the criteria for instability based on comparison of flexion and extension radiographs.

SUMMARY OF BACKGROUND DATA

Pain may limit full flexion and extension maneuvers and thereby lead to underreporting of true dynamic translation and angulation in LDS. Alternate imaging pairs may identify instability missed by flexion-extension.

MATERIALS AND METHODS

Consecutive patients scheduled for surgery for single-level L4-L5 LDS had preoperative standing radiographs in the lateral, flexion, and extension positions, supine computed tomography (CT) scans, and intraoperative fluoroscopic images in the supine and prone positions after anesthesia but before incision. Instability was defined as translation ≥3.5 mm or angulation ≥11° between the following pairs of images: (1) flexion-extension; (2) CT-lateral; (3) lateral-intraoperative supine; (4) lateral-intraoperative prone; and (5) intraoperative supine-prone.

RESULTS

Of 240 patients (mean age 68 y, 54% women) 15 (6%) met the criteria for instability by flexion-extension, and 225 were classified as stable. Of these 225, another 84 patients (35% of total enrollment) were reclassified as unstable by comparison of CT-lateral images (21 patients) and by lateral-intraoperative images (63 patients). Nine of the 15 patients diagnosed with instability by flexion-extension had fusion (60%), and 68 of the 84 patients reclassified as unstable by other imaging pairs had fusion (81%) ( P =0.07). The 84 reclassified patients were more likely to undergo fusion compared with the 141 patients who persistently remained classified as stable (odds ratio=2.6, 95% CI: 1.4-4.9, P =0.004).

CONCLUSIONS

Our study provides evidence that flexion and extension radiographs underreport the dynamic extent of LDS and therefore should not be solely relied upon to ascertain instability. These findings have implications for how instability should be established and the extent of surgery that is indicated.

High preoperative expectations and postoperative fulfillment of expectations two years after decompression alone and decompression plus fusion for lumbar degenerative spondylolisthesis

BACKGROUND CONTEXT

Fulfillment of expectations is a patient-centered outcome that has not been assessed based on fusion status for lumbar degenerative spondylolisthesis (LDS).

PURPOSE

To compare preoperatively cited expectations and 2-year postoperative fulfillment of expectations between patients undergoing decompression alone (no-fusion) vs. decompression plus fusion (fusion) for LDS.

STUDY DESIGN

Longitudinal cohort.

PATIENT SAMPLE

357 patients.

OUTCOME MEASURES

Postoperative version of Lumbar Spine Surgery Expectations Survey, Oswestry Disability Index (ODI), satisfaction with surgery.

METHODS

Preoperatively patients completed the 20-item Expectations Survey measuring amount of 'improvement expected' for symptoms, physical function, and psychosocial well-being (score range 0-100); two years postoperatively patients completed the follow-up Survey measuring 'improvement received'. The proportion of expectations fulfilled was calculated as 'improvement received' divided by 'improvement expected' (<1 some expectations fulfilled, >1 expectations surpassed). Patients also completed the ODI, SF-12 mental health subscale, satisfaction with surgery, and measures of comorbidity and psychosocial status, including social support (i.e. help at home) and prior orthopedic surgery (i.e. hip/knee arthroplasty).

RESULTS

Patients' mean age was 67 years, 61% were women, 82% had single-level LDS, 73% had fusion, and mean follow-up was 26.2 months. Compared to patients with no-fusion, patients with fusion had more pain, spinal instability, use of opioids, disability, and greater preoperative Expectations Survey scores (69 vs 74, p=.008). The proportion of expectations fulfilled postoperatively was high and similar for both groups (.82 vs. .79, p=.40), but more variable for fusion (IQR .32 vs. .40). In multivariable analysis with the proportion as the dependent variable, fulfilled expectations was associated with better mental well-being (coeff=1.1, 95% CI 0.6-1.7, p=.0001) and more social support (coeff=3.3, 95% CI 1.1-5.6, p=.004) and unfulfilled expectations was associated with prior arthroplasty (coeff=-8.6, 95% CI -15.4-(-1.9), p=.01) and subsequent lumbar surgery (coeff=-15.6, 95% CI -25.2-(-6.0), p=.002). Similar associations were found for change in ODI and satisfaction.

CONCLUSIONS

Patients had high preoperative expectations of surgery with greater expectations for decompression-fusion compared to decompression-alone. Although more variable for the fusion group, both groups had high proportions of expectations fulfilled. This study highlights the spectrum of clinical and psychosocial variables that impacts fulfillment of expectations for both decompression-alone and decompression-fusion for LDS surgery.