Journal Club: Characteristics of Sagittal Spinopelvic Alignment Changes After Symptom Relief After Simple Lumbar Decompression

Title and Citation

Characteristics of Sagittal Spinopelvic Alignment Changes After Symptom Relief After Simple Lumbar Decompression

Neurosurgery 2022

Background and importance

Sagittal spinal pelvic alignment used to determine/diagnose adult spinal deformities

Misdiagnosis can lead to inappropriate surgery

Trial design

Retrospective cohort

Analyzed patients who underwent lumbar decompression via laminectomy or laminectomy with discectomy without instrumentation

Full length, free standing lateral XR preoperatively and two months post operatively

Subgroups created base don preoperative ODI (ODI 4 or greater vs less than 4 preoperatively)

Sagittal spinopelvic alignment measures after lumbar decompressive surgery for HNP or LSS

Subgroup into symptomatic within 10 minutes of standing (SN –  no pain within 10 minutes of standing, SP – standing causes pain within 10 minutes)

Duration

April 2019-June 2021 (2 years and 2 months)

Objectives

Hypothesis: alleviation of pain while standing would improve SSPA

Differentiate sagittal spinopelvic alignment in symptomatic patients from asymptomatic patients within 10 minutes in standing position

Inclusion Criteria

Surgery for lumbar decompression (laminectomy or laminectomy with discectomy without instrumentation)

Exclusion Criteria

Missing ODI

Missing pre operative radiograph that could be measured for SSPA

Primary endpoint

Sacral slope

Pelvic tilt

Thoracic kyphosis

Global tilt

Lumbar lordosis (top of L1 angle to top of S1)

L4-S1 angle

Relative Sagittal Alignment (RSA)

Relative Lumbar Lordosis (RLL) = measured – ideal lumbar lordosis (ideal = PI x 0.62 + 29)

Lordosis Distribution Index (LDI) = (L4-S1 lordosis/L1-S1 lordosis)x100

Above compared preoperative vs 2 months postoperative

Statistical Analysis

Shapiro Wilk test

Simple T test (match subgroups)

Chi square test (match subgroups)

Paired sample t test (compare preoperative and postoperative SSPA)

Sensitivity Analysis

none

Results

No statistically significant difference in age, gender, BMI, or initial diagnoses between subgroups (standing with pain in 10 minutes, standing without pain in 10 minutes)

VAS in subgroups were statistically significant with higher scores in group with no pain upon standing in 10 minutes (counter intuitive)

RSA and RLA significantly corrected after surgery

SP demonstrated significant correction in RSA (P=.001) and RLL (<.001)

SN demonstrated no significant difference in RSA (P=.405) and RLL (P=.055)

If interested in further results may see paper however I am most familiar with measurements indicated below.

SP group (n=33)

Pelvic parameter	Pre op	Post Op	Change (P value)
C7 SVA	34.68	12.58	0.003
PI-LL	7.39	1.69	12.08

SN group (n=29)

Pelvic parameter	Pre op	Post Op	Change (P value)
C7 SVA	18.96	19.06	.986
PI-LL	2.55	2.55	0.025

Limitations

Follow up period was 2 months

Author’s Conclusion

Patients with pain within 10 minutes of standing showed significant improvements in RSA, RLL, and GAP scores after simple lumbar decompression

Adult spinal deformity diagnosis based on alignment scores instead of clinical symptoms may lead to unnecessary realignment surgeries

Weaknesses

Initial hypothesis was that alleviation of pain would improve SSPA; the groupings did not test hypothesis, subgroups should have been post operative pain relief vs post operative no pain relief

4 patients with preoperative ODI standing scores of 4 or higher who did not show postoperative improvements were excluded

Indicate 63 patients included in the study however groups SN (29) and SP (33) do not add up to 63

(concern about statistical analysis)

Applicability

Difficult to determine clinical utility. The authors argue that measurements may mislead to diagnosis of adult spinal deformity leading to realignment surgery. However all patients in the study received lumbar decompression, not a realignment surgery. Therefore physicians were able to identify that these patient despite pre operative measurements did not have adult spinal deformity, compensatory changes due to lumbar stenosis or herniated disc.