Faculty Bibliography

STUDY DESIGN/METHODS:Retrospective review. OBJECTIVE:Determine if patients with different degrees of incidence (PI) have the capacity to compensate via pelvic retroversion before initiating lower extremity compensation. SUMMARY OF BACKGROUND DATA/BACKGROUND:Compensatory mechanisms in the spine are thought to help patients with deformities maintain sagittal alignment. Pelvic retroversion and thoracic hypokyphosis are key mechanisms that help maintain balance. When these mechanisms are exhausted, patients often flex their hips and bend their knees. METHODS:This was a retrospective radiographic analysis of the EOS images at a single institution. Various spinal sagittal parameters and lower extremity knee flexion measurements were performed. Patients were subcategorized according to PI. Knee flexion in these groups was correlated with various sagittal parameters to determine whether there were differences when knee flexion occurred based on the PI. RESULTS:Knee flexion was independently correlated with PI, pelvic tilt (PT), PI-lumbar lordosis mismatch (PI-LL), and T1 pelvic inclination angle (TPA) in multiple regression analyses (P < 0.05). In patients with lower PI, knee flexion occurred at a PT of 10-15 degrees, PI-LL mismatch of -5-0 degrees, and TPA of about 10-15 degrees. In those with high PI, knee flexion occurred at a PT of ∼25-30 degrees, PI-LL mismatch of ∼15-20 degrees, and TPA about 25 degrees. Those with a lower PI also more rapidly increased knee flexion with further increases in PI-LL mismatch and TPA compared with those with a higher PI. CONCLUSION/CONCLUSIONS:This study demonstrates that patients with different PI have different capacities to compensate for increasing sagittal plane deformity before initiating knee flexion lower extremity compensation. Those with a lower PI retroverted their pelvis less and begin knee compensation earlier than those with a higher PI. These findings are important for surgical planning in patients with differing PI who are compensating for knee flexion.

STUDY DESIGN/METHODS:Retrospective cohort study of patients undergoing single-level L5-S1 anterior or transforaminal lumbar interbody fusion between 2012 and 2024 at a single academic institution, with preoperative and one-year postoperative radiographic assessment of sagittal alignment parameters. OBJECTIVE:To quantify changes in lumbar pelvic angle (LPA), pelvic tilt (PT), global lumbar lordosis (L1-S1), regional lumbar lordosis (L4-S1), and segmental lumbar lordosis (L5-S1) among single-level L5-S1 ALIF and TLIF patients. SUMMARY OF BACKGROUND DATA/BACKGROUND:Restoration of sagittal alignment is a primary goal of lumbar fusion. While ALIF is regarded as superior to TLIF in restoring segmental lordosis, its effect on global and regional alignment remains uncertain, and few studies directly compare their impact on spinopelvic parameters. METHODS:The electronic medical record was queried for patients who underwent single-level L5-S1 ALIF or TLIF with preoperative and one-year postoperative imaging. Sagittal parameters were measured using Surgimap software. Group comparisons were assessed with unpaired t-tests or Wilcoxon signed-rank tests. RESULTS:Radiographic measurements were available for 174 patients (ALIF n=73, TLIF n=101). ALIF patients had significantly greater improvement in L4-S1 (+4.2° vs. -1.1°, P=0.002) and L5-S1 lordosis (+4.6° vs. -4.8°, P<0.001). No significant differences were observed in postoperative changes for L1-S1 lordosis (+2.2° vs. -1.4°, P=0.250), LPA (-1.9° vs. -1.4°, P=0.743), or PT (-0.9° vs. +0.4°, P=0.093). Permutation testing confirmed that the observed difference in LPA improvement between cohorts (-0.51°) was not statistically significant (P=0.673), and post hoc analysis confirmed adequate power to detect a difference of 3.37°. Sensitivity analyses using ANCOVA, adjusting for baseline radiographic values and covariates, were concordant. CONCLUSION/CONCLUSIONS:ALIF provided superior regional and segmental lordosis but did not improve global alignment compared with TLIF. This study is the first to quantify the effect of ALIF versus TLIF on LPA, highlighting the limited impact of single-level fusion on global spinopelvic alignment.

PURPOSE/OBJECTIVE:Vertebral body tethering (VBT) offers a fusion-less alternative for adolescent idiopathic scoliosis (AIS) patients, with tether breakage being a common concern, particularly in single-row VBT. Limited data exist on double-row VBT's impact on tether breakage. This study evaluates a two-row vertebral body tethering (2RVBT) technique, comparing cases with and without broken tethers in patients with over 2 year follow-up. METHODS:A single-center, retrospective review (2019-2022) included AIS patients who underwent mini-open thoracoscopic-assisted 2RVBT. Inclusion criteria were idiopathic scoliosis < 65° flexible curves, residual post-operative curves < 30°, and ≥ 2 year follow-up. Patients were divided into broken-tether (BT) and non-broken-tether (NBT) groups. Radiographic measures included thoracic (T) and thoracolumbar (TL) Cobb angles, coronal balance, L5 tilt, and sagittal parameters. Tether breakage was defined by > 5° change in screw angulation, with or without associated loss of correction. RESULTS:Among 109 patients (NBT = 94, BT = 15), the overall tether breakage rate was 13.7%. The BT group had significantly larger pre-operative TL Cobb angles (53.4 ± 14.0° vs 43.7 ± 13.8°, p = 0.02), greater TL correction (- 36.2 ± 9.1° vs -2 3.7 ± 15.9°, p = 0.002), and higher post-operative coronal imbalance (21.2 ± 14.6 mm vs 11.9 ± 9.4 mm, p = 0.049). They also had significantly lower skeletal maturity (mean Risser stage 2.0 ± 1.1 vs 3.2 ± 1.3, p = 0.019; Sanders 4.0 ± 1.5 vs 5.4 ± 2.0, p = 0.019). Most broken tethers did not require revision, but some cases underwent re-tethering or fusion. CONCLUSION/CONCLUSIONS:Double tether constructs may reduce the rate of tether breakage following VBT. The main risk factors for tether breakage following double tether VBT are residual post-operative coronal imbalance, larger corrections in the lumbar spine, large rigid thoracic curves, and skeletal immaturity. Furthermore, most broken tethers did not require revision, which may indicate that curves maintained appropriate correction post-breakage due to the functional lifespan of double tether constructs. Although these are preliminary findings that must be supported with further multicenter studies that include single-tether constructs, these findings should be taken into consideration when indicating patients for VBT.

STUDY DESIGN/METHODS:Single-center retrospective study. OBJECTIVE:To evaluate the risks associated with postoperative kyphosis and loss of range of motion after cervical disc replacement (CDR). SUMMARY OF BACKGROUND DATA/BACKGROUND:One of the main benefits of CDR is that it maintains physiological range of motion (ROM) and lordosis while achieving decompression. However, some patients experience loss in segmental ROM or postoperative segmental kyphosis. This study analyzes the radiographic outcomes of these patients. METHODS:Adult patients who underwent CDR were included. The cohort was divided into patients with poor x-ray outcomes (PXR) and successful x-ray outcomes (SXR). The PXR group was defined as patients who had a loss in segmental ROM (≥11 degress decrease in Δ segmental ROM) after CDR and/or postoperative segmental kyphosis at the operative level at 2-year follow-up. Sagittal alignment and other measures were compared. RESULTS:A total of 151 (PXR=47; SXR=104) patients met the inclusion criteria. Pre- and postoperative segmental lateral Cobb angles were more kyphotic in the PXR group (3.5 vs. -1.4 degress, P<0.001; 2.6 vs. -5.6 degress, P<0.001). There was a larger Δ in segmental lateral Cobb angle in the SXR group (-4.2 vs. -0.9 degress, P<0.001). The PXR group had more flexion and less extension (11.3 degress vs. 6.5 degress, P<0.001; -2.2 vs. -6.1 degress, P=0.049). Segmental ROM loss was significant in the PXR group (-5.7 degress vs. 1.5 degress, P<0.001). Pre- and postoperative C2-C7 lateral Cobb angles were more kyphotic in the PXR group (-1.2 vs. -9.4 degress, P<0.001; -2.9 vs. -13.9 degress, P<0.001). Pre- and postoperative cSVA were larger in the PXR group (29.6 vs. 25.3 mm, P=0.047; 30.1 vs. 22.8 mm, P=0.004). Multiple variable regressions showed higher preoperative segmental lateral Cobb angle increased odds of SXR (OR=1.217, 95% CI: 1.083-1.369, P<0.001), while larger preoperative C2-C7 ROM decreased them (OR=0.970, 95% CI: 0.994-0.996, P=0.024). No significant differences in postoperative complications were observed. CONCLUSIONS:Patients with postoperative kyphosis or loss of ROM were more likely to have less segmental and regional C2-7 lordosis and a larger cSVA. Surgeons should consider these preoperative parameters when indicating CDR and counseling patients.

STUDY DESIGN/METHODS:Retrospective cohort study. OBJECTIVE:To develop parameter thresholds obtainable from cervical radiographs that correlate with concomitant thoracolumbar malalignment. SUMMARY OF BACKGROUND DATA/BACKGROUND:T1 slope (T1S) is typically discussed in the context of cervical deformity and correlated with health-related quality of life outcomes. Prior research suggests that T1S is related to global alignment; however, a definition for "high" T1S has not been established. Most patients undergoing cervical surgery do not undergo full-spine imaging; therefore, obtaining a parameter associated with thoracolumbar malalignment from cervical radiographs would be beneficial. METHODS:A database of preoperative adult spinal deformity (ASD) patients was analyzed. Measures obtained from standing lateral radiographs included T1S, thoracic kyphosis (TK), sagittal vertical axis (SVA), T1-pelvic angle (TPA), pelvic tilt (PT), and pelvic incidence minus lumbar lordosis (PI-LL). Decision tree analysis was then used to determine the T1S corresponding to published thresholds for high TK (40 degrees), SVA (40 mm), TPA (25 degrees), and PT (25 degrees). Alignment between high and normal T1S patients was compared. RESULTS:Two hundred twenty-six preoperative patients were included (mean: 58±16 y 62%F). Larger T1S was correlated with greater SVA (r=0.365), TPA (r=0.302), TK (r=0.606), and PT (r=0.230) (all P<0.001). Decision tree analysis yielded a threshold of 30 degrees for high T1S, which 50% of patients had. Compared with patients with T1S <30 degrees, those with T1S >30 degrees had higher TK (41.5 vs. 25.8 degrees), SVA (78.7 vs. 33.7 mm), TPA (27.6 vs. 18.3 degrees), and PT (26.3 vs. 20.8 degrees), and PI-LL (18.2 vs. 11.7 degrees) (all P<0.05). Seventy-nine percent of patients with high T1S had high TK (T1S <30=13%), 69% had high SVA (T1S <30=38%), 66% had high TPA (T1S <30=37%), 60% had PT >25 degrees (T1S <30=42%), and 47% had PI-LL >20 degrees (T1S <30=34%) (all P<0.05). CONCLUSION/CONCLUSIONS:Higher T1S was associated with worse global alignment. T1S was most strongly associated with TK. A T1S=30 degrees corresponded to high TK, SVA, TPA, and PT thresholds. Therefore, surgeons should consider obtaining full-spine radiographs if a T1S >30 degrees is present on cervical imaging.

BACKGROUND/UNASSIGNED:open or minimally invasive (MIS) laminectomy using the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP) database. METHODS/UNASSIGNED:Using the ACS-NSQIP database from 2017 to 2022, Current Procedural Terminology (CPT) code of 63030 or 62380 were used to filter the dataset between open/tubular retractor-based and endoscopic single-level lumbar decompression cases, respectively. Overall, as collected, the endoscopic group consisted of 336 patients and the non-endoscopic group had 55,111 patients. The groups were compared to evaluate the patient characteristics and adverse events within 30 days after their operation. Outcome measures compared were operative time, length of stay (days), adverse outcomes [superficial infection, deep infection, organ/space infection, wound dehiscence, pneumonia, unplanned intubation, pulmonary embolism, ventilator >48 hours, progressive renal insufficiency, acute renal failure, urinary tract infection, stroke/cerebrovascular accident (CVA) accident, cardiac arrest, myocardial infarction, blood transfusion, deep vein thrombosis (DVT), sepsis, and septic shock], 30-day readmission, return to operating room (OR). RESULTS/UNASSIGNED:4.8%, P=0.01), with significantly lower rate of blood transfusions (P<0.05) compared to the non-endoscopic group. CONCLUSIONS/UNASSIGNED:Patients who underwent endoscopic lumbar decompression demonstrated a significantly lower rate of total adverse events and significantly lower rate of blood transfusions compared to their counterparts. This data from the ACS-NSQIP supports the reported benefits of endoscopic technique in the current literature. As endoscopic surgery becomes more widely utilized throughout the United States, more data will become available for further studies.

PURPOSE/OBJECTIVE:Clinical trials have studied the effects of curve magnitude and flexibility, age, and skeletal immaturity on the outcomes of VBT. No studies have assessed the effect of Lenke curve type on the outcomes of VBT. This study compares outcomes in patients who underwent VBT with Lenke type 1, 3, 5, and 6 curves. METHODS:Single center retrospective review of patients undergoing mini-open thoracoscopic-assisted two row vertebral body tethering (2RVBT) for the correction of AIS with a minimum 2-year follow-up were included. Patients were grouped by Lenke type, which yielded 4 groups; types 1, 3, 5, or 6. Analysis included preoperative demographic parameters, as well as radiographic and clinical outcome measures. RESULTS:156 2RVBT (Lenke 1, N = 61; Lenke 3, N = 35; Lenke 5, N = 37; Lenke 6, N = 23) patients met inclusion criteria. The mean preoperative apex Cobb angle in the Lenke type 1, 3, 5, and 6 groups were 50.2 ± 9.1, 50.5 ± 10.1, 45.0 ± 8.6, and 49.0 ± 10.8, respectively. This corrected to 21.2 ± 10.2, 19.2 ± 8.5, 13.6 ± 7.2, 18.5 ± 8.3 in Lenke type 1, 3, 5, and 6 groups, respectively, demonstrating that Lenke type 5 saw greatest correction following 2RVBT. With regards to revision recommendation following tether breakage, Lenke type 3 curves were most frequently indicated for fusion, whereas Lenke type 1 curves were most frequently not indicated for revision surgery. CONCLUSION/CONCLUSIONS:Lenke type 5 curves are the most amenable to correction via 2RVBT, as evident by their lower post-operative apex Cobb angles and lowest rate of recommendation for revision to posterior spinal fusion.

BACKGROUND/UNASSIGNED:Surgical decompression of degenerative lumbar central stenosis, in older patients, has been shown to provide improved outcomes compared to conservative treatment. However, in elderly patients lacking instability, there still lacks a consensus on whether fusion is needed following decompression and whether the argument extends to cases involving multiple levels. METHODS/UNASSIGNED:Patients ≥ 65 years of age undergoing 2-4 multilevel laminectomies were included in the study. Intervertebral displacement was measured as the sagittal translation of each vertebral segment from L1 to S1 from flexion-extension films. Analyses of surgical and clinical outcomes were performed between decompression alone (MD) and decompression with fusion (MDF) groups through independent sample t-tests and Chi-square analyses. Propensity-score analysis was conducted to match patients from each group based on the number of levels decompressed and intervertebral stability. RESULTS/UNASSIGNED:= 0.075). At 1 year, MD and MDF groups experienced equivalent clinical outcomes, including radiculopathy, revision, and patient-reported measures. CONCLUSION/UNASSIGNED:Our data suggest that in elderly patients with similar baseline traits, multilevel decompression without fusion can provide improved perioperative outcomes with noninferior results at 1 year compared to with fusion.

STUDY DESIGN/METHODS:Retrospective analysis. OBJECTIVES/OBJECTIVE:To evaluate resolution of radiculopathy in one-level lumbar fusion with indirect or direct decompression techniques. METHODS:< .05. RESULTS:116 patients were included: 58 direct decompression (DD) (mean 53.9y, 67.2% female) and 58 indirect decompression (ID) (mean 54.6y, 61.4% female). DD patients experienced greater blood loss than ID. Additionally, DD patients were 4.7 times more likely than ID patients to experience full resolution of radiculopathy at 3 months post-op. By 6 months, DD patients demonstrated larger reductions in VAS score. With regard to motor function, DD patients had improved motor score associated with the L5 dermatome at 6 months relative to ID patients. CONCLUSIONS:Direct decompression was associated with greater resolution of radiculopathy in the near post-operative term, with no differences at long term follow-up when compared with indirect decompression. In particularly debilitated patients, these findings may influence surgeons to perform a direct decompression to achieve more rapid resolution of radiculopathy symptoms.

STUDY DESIGN/METHODS:Retrospective analysis of prospectively collected data. OBJECTIVE:To investigate the effect of the approach of the transforaminal lumbar interbody fusion [TLIF; open vs . minimally invasive (MIS)] on reoperation rates due to ASD at 2 to 4-year follow-up. SUMMARY OF BACKGROUND DATA/BACKGROUND:Adjacent segment degeneration is a complication of lumbar fusion surgery, which may progress to adjacent segment disease (ASD) and cause debilitating postoperative pain potentially requiring additional operative management for relief. MIS TLIF surgery has been introduced to minimize this complication but the impact on ASD incidence is unclear. MATERIALS AND METHODS/METHODS:For a cohort of patients undergoing 1 or 2-level primary TLIF between 2013 and 2019, patient demographics and follow-up outcomes were collected and compared among patients who underwent open versus MIS TLIF using the Mann-Whitney U test, Fischer exact test, and binary logistic regression. RESULTS:Two hundred thirty-eight patients met the inclusion criteria. There was a significant difference in revision rates due to ASD between MIS and open TLIFs at 2 (5.8% vs . 15.4%, P =0.021) and 3 (8% vs . 23.2%, P =0.03) year follow-up, with open TLIFs demonstrating significantly higher revision rates. The surgical approach was the only independent predictor of reoperation rates at both 2 and 3-year follow-ups (2 yr, P =0.009; 3 yr, P =0.011). CONCLUSIONS:Open TLIF was found to have a significantly higher rate of reoperation due to ASD compared with the MIS approach. In addition, the surgical approach (MIS vs . open) seems to be an independent predictor of reoperation rates.