Global sagittal spinal alignment in patients with degenerative low-grade lumbar spondylolisthesis

Degenerative lumbar spondylolisthesis: review of current classifications and proposal of a novel classification system

PURPOSE

To review existing classification systems for degenerative spondylolisthesis (DS), propose a novel classification designed to better address clinically relevant radiographic and clinical features of disease, and determine the inter- and intraobserver reliability of this new system for classifying DS.

METHODS

The proposed classification system includes four components: 1) segmental dynamic instability, 2) location of spinal stenosis, 3) sagittal alignment, and 4) primary clinical presentation. To establish the reliability of this system, 12 observers graded 10 premarked test cases twice each. Kappa values were calculated to assess the inter- and intraobserver reliability for each of the four components separately.

RESULTS

Interobserver reliability for dynamic instability, location of stenosis, sagittal alignment, and clinical presentation was 0.94, 0.80, 0.87, and 1.00, respectively. Intraobserver reliability for dynamic instability, location of stenosis, sagittal alignment, and clinical presentation were 0.91, 0.88, 0.87, and 0.97, respectively.

CONCLUSION

The UCSF DS classification system provides a novel framework for assessing DS based on radiographic and clinical parameters with established implications for surgical treatment. The almost perfect interobserver and intraobserver reliability observed for all components of this system demonstrates that it is simple and easy to use. In clinical practice, this classification may allow subclassification of similar patients into groups that may benefit from distinct treatment strategies, leading to the development of algorithms to help guide selection of an optimal surgical approach. Future work will focus on the clinical validation of this system, with the goal of providing for more evidence-based, standardized approaches to treatment and improved outcomes for patients with DS.

Sagittal Alignment in the Degenerative Lumbar Spine: Surgical Planning

➤ Sagittal alignment of the spine has gained attention in the field of spinal deformity surgery for decades. However, emerging data support the importance of restoring segmental lumbar lordosis and lumbar spinal shape according to the pelvic morphology when surgically addressing degenerative lumbar pathologies such as degenerative disc disease and spondylolisthesis.➤ The distribution of caudal lordosis (L4-S1) and cranial lordosis (L1-L4) as a percentage of global lordosis varies by pelvic incidence (PI), with cephalad lordosis increasing its contribution to total lordosis as PI increases.➤ Spinal fusion may lead to iatrogenic deformity if performed without attention to lordosis magnitude and location in the lumbar spine.➤ A solid foundation of knowledge with regard to optimal spinal sagittal alignment is beneficial when performing lumbar spinal surgery, and thoughtful planning and execution of lumbar fusions with a focus on alignment may improve patient outcomes.

Lumbar degenerative spondylolisthesis: role of sagittal alignment

PURPOSE

To evaluate the sagittal alignment of the lumbar spine in patients with degenerative spondylolisthesis at the L4-5 level.

METHODS

Patients with untreated degenerative spondylolisthesis at L4-5 were retrospectively identified from the clinical practice of spine surgeons at an academic medical center. All patients had standing X-rays that were reviewed by the senior surgeon to confirm the presence of degenerative spondylolisthesis at L4-5. Radiographs were analyzed for the following: lumbar lordosis (LL), lower lumbar lordosis (L4-S1; LLL), L5-S1 lordosis, pelvic incidence (PI), and pelvic tilt (PT). From these measurements, lumbar distribution index (LLL/LL × 100; LDI), ideal lumbar lordosis (PI × 0.62 + 29; ILL), PI-LL mismatch, and relative lumbar lordosis (LL-ILL; RLL) were calculated. These parameters were used to evaluate the sagittal alignment of the lumbar spine. Normal alignment was defined based on previous studies and clinical experience.

RESULTS

117 participants met inclusion criteria, with an average age of 67.2 years. The majority of the cohort demonstrated hypolordotic sagittal alignment of the L5-S1 segment when assessed in relation to ILL, PI, and LL (73.5%, 61.5%, and 50.4% respectively). Evaluation of the lower lumbar spine (L4-S1) demonstrated normal sagittal alignment when evaluated via LDI and LLL (65%, 52.1%, respectively), suggesting the presence of compensatory hyperextension at L4-5 in response to the L5-S1 hypolordosis. Consequently, normal sagittal alignment of the regional lumbar spine was maintained when evaluated using LL, PI-LL mismatch, and RLL (51.3%, 47%, and 62.4% respectively).

CONCLUSIONS

This study demonstrates that there is a high incidence of relative hypolordosis at the L5-S1 level among patients who present with degenerative spondylolisthesis at L4-5. The L5-S1 hypolordosis is associated with L4-5 hyperlordosis, such that the lower lumbar lordosis (L4-S1; LLL) and regional lumbar lordosis (LL) are still within normal range. It is probable that L5-S1 hypolordosis was the initial pathologic event that incited compensatory L4-5 hyperlordosis, which in turn may have led to facet degeneration and laxity, and eventually to development of spondylolisthesis.

Sacroiliac joint degeneration in degenerative lumbar spondylolisthesis and related risk factors: a retrospective study

OBJECTIVE

This study was performed to evaluate the degree of radiological sacroiliac joint (SIJ) degeneration in patients with degenerative lumbar spondylolisthesis (DLS). The related risk factors for SIJ degeneration were also investigated.

METHODS

We retrospectively analyzed the lumbar and pelvic computed tomography (CT) scans of 303 patients with DLS admitted from January 2018 to December 2021. One hundred and fifty-six age-, gender-, and body mass index-matched patients without lumbar anomality who underwent lower abdominal or pelvic computed tomography scans were included in the control group. Sagittal parameters were measured on full-length lateral radiographs. Two protocols (Backlund's grade and Eno's classification) were used to assess SIJ degeneration. Univariate analysis and bivariate and multivariate regression analysis were performed to identify the factors affecting SIJ degeneration in patients with DLS.

RESULTS

According to Backlund's grade and Eno's classification, SIJ degeneration was more severe in the DLS group than in the control group (P < 0.001). Multi-segment degenerative changes (P = 0.032), two-level DLS (P = 0.033), a history of hysterectomy (P < 0.001), lower extremity pain (P = 0.016), and pelvic pain (P = 0.013) were associated with more significant SIJ degeneration as assessed by Backlund's grade. The results of Pearson's correlation analysis showed positive correlation between the sagittal vertical axis and SIJ degeneration (r = 0.232, P = 0.009). The multivariate linear regression analysis showed that a history of hysterectomy was significantly correlated with SIJ degeneration in patients with DLS (r = 1.951, P = 0.008).

CONCLUSIONS

SIJ degeneration was more severe in patients with than without DLS. We should take SIJ degeneration into consideration when diagnosing and treating DLS especially those who had undergone previous hysterectomy or showed sagittal malalignment.

Should patients with lumbar stenosis and grade I spondylolisthesis be treated differently based on spinopelvic alignment? A retrospective, two-year, propensity matched, comparison of patient-reported outcome measures and clinical outcomes from multiple sites within a single health system

BACKGROUND

Degenerative lumbar spondylolisthesis is one of the most common pathologies addressed by surgeons. Recently, data demonstrated improved outcomes with fusion in conjunction with laminectomy compared to laminectomy alone. However, given not all degenerative spondylolistheses are clinically comparable, the best treatment option may depend on multiple parameters. Specifically, the impact of spinopelvic alignment on patient reported and clinical outcomes following fusion versus decompression for grade I spondylolisthesis has yet to be explored.

PURPOSE

This study assessed two-year clinical outcomes and one-year patient reported outcomes following laminectomy with concomitant fusion versus laminectomy alone for management of grade I degenerative spondylolisthesis and stenosis. The present study is the first to examine the effect of spinopelvic alignment on patient-reported and clinical outcomes following decompression alone versus decompression with fusion.

STUDY DESIGN/SETTING

Retrospective sub-group analysis of observational, prospectively collected cohort study.

PATIENT SAMPLE

679 patients treated with laminectomy with fusion or laminectomy alone for grade I degenerative spondylolisthesis and comorbid spinal stenosis performed by orthopaedic and neurosurgeons at three medical centers affiliated with a single, tertiary care center.

OUTCOME MEASURES

The primary outcome was the change in Patient-Reported Outcome Measurement Information System (PROMIS), Global Physical Health (GPH), and Global Mental Health (GMH) scores at baseline and post-operatively at 4-6 and 10-12 months postoperatively. Secondary outcomes included operative parameters (estimated blood loss and operative time), and two-year clinical outcomes including reoperations, duration of postoperative physical therapy, and discharge disposition.

METHODS

Radiographs/MRIs assessed stenosis, spondylolisthesis, pelvic incidence, lumbar lordosis, sacral slope, and pelvic tilt; from this data, two cohorts were created based on pelvic incidence minus lumbar lordosis (PILL), denoted as "high" and "low" mismatch. Patients underwent either decompression or decompression with fusion; propensity score matching (PSM) and coarsened exact matching (CEM) were used to create matched cohorts of "cases" (fusion) and "controls" (decompression). Binary comparisons used McNemar test; continuous outcomes used Wilcoxon rank-sum test. Between-group comparisons of changes in PROMIS GPH and GMH scores were analyzed using mixed-effects models; analyses were conducted separately for patients with high and low pelvic incidence-lumbar lordosis (PILL) mismatch.

RESULTS

49.9% of patients (339) underwent lumbar decompression with fusion, while 50.1% (340) received decompression. In the high PLL mismatch cohort at 10-12 months postoperatively, fusion-treated patients reported improved PROs, including GMH (26.61 vs. 20.75, p<0.0001) and GPH (23.61 vs. 18.13, p<0.0001). They also required fewer months of outpatient physical therapy (1.61 vs. 3.65, p<0.0001) and had lower 2-year reoperation rates (12.63% vs. 17.89%, p=0.0442) compared to decompression-only patients. In contrast, in the low PLL mismatch cohort, fusion-treated patients demonstrated worse endpoint PROs (GMH: 18.67 vs. 21.52, p<0.0001; GPH: 16.08 vs. 20.74, p<0.0001). They were also more likely to require skilled nursing/rehabilitation centers (6.86% vs. 0.98%, p=0.0412) and extended outpatient physical therapy (2.47 vs. 1.34 months, p<0.0001) and had higher 2-year reoperation rates (25.49% vs. 14.71%,p=0.0152).

CONCLUSIONS

Lumbar laminectomy with fusion was superior to laminectomy in health-related quality of life and reoperation rate at two years postoperatively only for patients with sagittal malalignment, represented by high PILL mismatch. In contrast, the addition of fusion for patients with low-grade spondylolisthesis, spinal stenosis, and spinopelvic harmony (low PILL mismatch) resulted in worse quality of life outcomes and reoperation rates.

Influence of sagittal degenerative spondylolisthesis on anteversion of the acetabular component in total hip arthroplasty

BACKGROUND

Degenerative lumbar spondylolisthesis (DSPL), as opposed to other degenerative spinal conditions, is disregarded in the assessment of hip stability after total hip arthroplasty (THA). This study aimed to determine whether patients with DSPL have different acetabular anteversion compared to patients with normal spine before and following THA.

METHODS

Preoperative and postoperative 6‑month lateral pelvic radiographs in standing and sitting positions from 91 patients who underwent primary THA were retrospectively compared for spinopelvic parameters between patients with DSPL (n = 31) and with normal spine (n = 34).

RESULTS

Compared to control patients in the standing position, patients with DSPL had significantly increased preoperative pelvic tilt (24° in DSPL vs. 8° in controls; p < 0.01), pelvic-femoral angle (194° in DSPL vs. 174° in controls; p < 0.05), decreased lumbar lordosis (35° in DSPL vs. 43° in controls; p < 0.05), increased postoperative pelvic tilt (22° in DSPL vs. 7° in controls; p < 0.01), pelvic-femoral angle (187° in DSPL vs. 179° in controls; p < 0.05), and acetabular anteversion (31° in DSPL vs. 23° in controls; p < 0.05). Preoperative (p = 0.181) and postoperative (p = 0.201) sitting pelvic tilt did not differ. There were positive correlations between preoperative standing pelvic tilt and postoperative standing acetabular anteversion, pelvic-femoral angle, and combined sagittal index (CSI) in DSPL (R² = 0.8416; R² = 0.9180; R² = 0.9459, respectively, p < 0.01) and in controls (R² = 0.6872; R² = 0.6176; R² = 0.7129, respectively, p < 0.01).

CONCLUSION

While the imbalance of seated sagittal plane is usually insignificant and compensable, the mechanism by which DSPL patients achieve a standing posture is different from control patients, with more hip extension and posterior tilt of the pelvis. Special attention should be paid to the risk of impingement caused by the increase of acetabular anteversion in the postoperative standing position.