Faculty Bibliography

BACKGROUND CONTEXT: Sacralization of L5 is a condition that affects 15% of the population. Because of the increased L5 articulations to the sacrum, it is unclear how pelvic incidence and spinopelvic parameters should be measured. PURPOSE: Determine whether patients with L5 sacralization should be radiographically measured with relation to the L5 or S1 vertebrae. STUDY DESIGN/SETTING: Retrospective analysis. PATIENT SAMPLE: Prospective multicenter adult spinal deformity database. OUTCOME MEASURES: ODI, SF36 PCS, radiographic spinopelvic parameters.
METHOD(S): Linear regression modeling was used to determine normative TPA and PI-LL based on PI and age in a database of asymptomatic subjects. In an adult spinal deformity database, patients with radiographic evidence of L5 sacralization, had PI, LL and TPA measured from the superior endplate S1 and then also from L5. Patients with instrumentation below L4 at baseline were excluded. The differences in TPA and PI-LL from normative were calculated in the sacralization cohort relative to L5 and S1 and correlated to ODI. Patients were grouped based on PI-LL Schwab modifier (0, +, ++) utilizing their L5 PI-LL and S1 PI-LL. Baseline ODI and SF36 PCS were compared across and within groups and their respective SRS Schwab class.
RESULT(S): Among 1,179 ASD patients, 276 (23.4%) had transitional anatomy, 176 with sacralized L5 (14.9%) and 100 (8.48%) with lumbarization of S1. The 176 with sacralized L5 were analyzed. PI (24.5 +/- 11.0 vs 55.7 +/- 12.0, p=0.001), TPA (11.2 +/- 12.0 vs 20.3 +/- 12.5, p=0.001) and PI-LL (0.67 +/- 21.1 vs 11.4 +/- 20.8, p=0.001) measured utilizing the L5 superior endplate were significantly smaller than those who were measured relative to S1. When measured from S1, 76 (43. %) of patients were SRS Schwab 0, 45 (25.6%) were Class +, and 55 (31.3%) were class ++ compared to 124 (70.5%), 22 (12.5%), and 30 (17.0%) measured from L5 respectively. There were significant differences in ODI and PCS as the Schwab grade increased regardless of L5 or S1 measurement. The L5 group had higher PCS functional scores for Schwab 0 and ++ relative to same grades in the S1 group. Offset from normative TPA (0.5 +/- 11.1 vs 9.6 +/- 10.8, p=0.001) and PI-LL (0.67 +/- 21.1 vs 11.4 +/- 20.8, p=0.001) were smaller when measuring from L5. Moreover, S1 measurements were more correlated with disability by ODI (TPA offset from normative, S1: R=0.326 vs L5: R=0.285; PI-LL Offset from normative, S1: R=0.318 vs L5: R=0.274).
CONCLUSION(S): Measuring the PI at L5 in sacralized anatomy results in underestimating the PILL Schwab grade in a percentage of patients and less correlation with HRQLs. Patients with sacralized L5s should have spinopelvic parameters measured relative to S1. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Sagittal alignment is integral to a patient's quality of life. Posterior spinal fusion (PSF) is currently the standard for correcting adolescent idiopathic scoliosis (AIS). Vertebral body tethering (VBT) is a fusionless growth modulating surgical technique used to treat AIS. It relies on the Hueter-Volkmann Law. Indications for this procedure include patients who have coronal curves up to 50degree, growth remaining, and no excessive thoracic kyphosis. VBT has been shown to have good coronal plane deformity correction. There have been fewer examinations of the sagittal effects of VBT. PURPOSE: To determine if VBT is a non-inferior treatment for correction of AIS with regard to sagittal alignment compared to PSF. STUDY DESIGN/SETTING: Multicenter retrospective cohort study. PATIENT SAMPLE: Patients with AIS who underwent correction surgeries with LIV in the lumbar spine from 2013 to 2021 with pre- and minimum two-year postoperative standing full spine plain films. OUTCOME MEASURES: Sagittal vertical axis (SVA), cervical SVA (cSVA), pelvic tilt (PT), thoracic kyphosis (TK), cervical lordosis (CL), L4-S1 lordosis (L4L), T1 pelvic angle (TPA) and pelvic incidence lumbar lordosis mismatch (PI-LL).
METHOD(S): Radiographic analyses was completed with independent samples t-test with significance set to p <0.05.
RESULT(S): A total of 99 patients were included, 49 VBT and 50 PSF. There were no differences in age or levels instrumented between groups. The VBT cohort Lenke class breakdown is 23% 1A, 13% 1C, 31% 3C. 18% 5C, and 15% 6C, while the PSF cohort consisted of 42% 1A, 6% 1B, 2% 2C, 2% 3B, 12% 3C, 2% 5B, 24% 5C, and 10% 6C. At Baseline, the VBT cohort had lower SVA (-0.7mm+/-3.7 vs 2.2mm+/-5.0, p=0.001), CL (-0.9degree+/-18.2 vs 11.6degree+/-12.8, p=0.001), L4-S1 Lordosis (20.7degree+/-16.0 vs 41.6degree+/-10.2, p=0.001), and higher cSVA (3.3mm+/-1.6 vs -0.95mm+/-3.1, p=0.001) than those who were fused. Postoperatively, VBT patients have an overall higher L4-S1 Lordosis (36.0degree+/-10.1vs 18.3degree+/-12.5, p=0.001), cSVA (3.4mm+/-1.4 vs -3.7mm+/-2.1, p=0.001), and lower CL (-4.3degree+/-18.4 vs 7.0degree+/-12.2, p=0.001). The PSF cohort had a larger change in cSVA (2.8mm+/-4.0 vs 0mm+/-1.6, p=0.001) from baseline to 2-year follow-up compared to VBT. No differences in the change of L4-S1 Lordosis (VBT 1.5degree+/-12.3 vs 4.1degree+/-10.9, p=0.3), TPA (VBT -1.6degree+/-6.8 vs -1.4degree+/-8.5, p=0.89), PT (VBT -0.5degree+/-7.8 vs -1.9degree+/-8.5, p=0.42), or PI-LL (0.2degree+/-12.0 vs -0.5degree+/-14.0, p=0.81) were observed.
CONCLUSION(S): VBT and PSF for AIS result in statistically similar changes in sagittal alignment parameters. The fact that we showed similar results comparing sagittal alignment in fusion and VBT groups indicates that VBT is non-inferior from a sagittal perspective. It is important to maintain sagittal alignment when correcting AIS. Future work can examine the long-term effect of VBT on sagittal alignment. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Loss of lumbar curvature is often expressed as an angular regional loss. Previous work comparing adult spinal deformity (ASD) lumbar alignment to their age-and-PI adjusted normative value demonstrated that, contrary to general belief, a large proportion of the curvature is lost proximally (L1-L4). This study is a follow-up looking not only at regional angles, but also at the spinal contour collectively. PURPOSE: Investigate the difference of lumbar shape between ASD and age-and-PI adjusted normative values. STUDY DESIGN/SETTING: Retrospective review of an ASD registry. PATIENT SAMPLE: A total of 119 asymptomatic volunteers and 362 ASD patients. OUTCOME MEASURES: Sagittal alignment of the lumbar and thoracolumbar spine measures using vertebra pelvic angle from L5 to T10.
METHOD(S): Before studying ASD patients, 119 asymptomatic volunteers with full-body, free-standing radiographs were used to identify age-and-PI models of each vertebra pelvic angle (VPA) from L5 to T10, a validated methodology characterizing the detailed shape of the spine. Our study cohort was a registry of surgical primary ASD patients without coronal malalignment (SRS-Schwab Type=N). The formulas developed in the asymptomatic population were applied to the ASD group to calculate an age-and-PI normative spine shape for each patient. Loss of lumbar lordosis was defined as the offset between age-and-PI normative value and pre-operative spino-pelvic alignment. Patients were stratified into four groups by the amount of lordosis lost, ranging from "no loss" to "30degree loss." Paired t-tests were performed to compare actual and normative VPA shapes within each group.
RESULT(S): Out of 1,495 patients enrolled in this registry, 453 were primary cases, and 653 were categorized as a Schwab type N, leading to a cohort of 362 patients (age=64.4+/-13, 57.1% F). Pre-operative alignment demonstrated a large variability with a mean PI-LL of 15degree+/-21, distal LL=31degree+/-15, and PI=55degree+/-13. Compared to their age-and-PI normative values, ASD patients demonstrated a significant lordosis loss of 17degree+/-19 with the following distribution: 14.1% no loss (mean: 0.1+/-2.3), 22.9% with 10degree loss (mean: 9.9+/-2.9), 22.1% with 20degree loss (mean: 20.0+/-2.8), and 29.3% with 30degree loss (mean:33.8+/-6.0). Comparison of the VPAs (and therefore the shape) between each LL group and the normative shape demonstrated that the "no loss" patients had a lumbar spine slightly anterior to the normative shape from L4 to T10 (VPA difference of 2degree). The shape of the "small deformity" group (10degree) superimposed on the normative one from L5 to L2 (VPA with p>0.1) and became anterior at the L1 level. As the lordosis loss increased, the offset between ASD and normative shapes began to propagate to the distal levels and became significant extending caudally to the L3 level for the "20degree loss" group and further down to L4 for the more severe group.
CONCLUSION(S): As the deformity progresses and the loss of lordosis increases, the difference between ASD shape and normative shape happens first proximally and then progresses incrementally caudally with increasing deformity. Understanding the spinal contour and the location of this loss, in addition to regional parameters, may be key to achieving a sustainable correction by identifying optimal and personalized post-operative shape. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Adult spinal deformity (ASD) patients maintain upright posture by compensating through their spine, pelvis and lower extremities. Little data exist quantifying the contribution of lower extremity compensation through the hips, knees, and ankles to maintain upright posture. PURPOSE: Evaluate the effect of the lower limb compensation by numerically unfolding patients. STUDY DESIGN/SETTING: Multicenter, prospective cohort. PATIENT SAMPLE: A total of 288 patients surgically treated for complex ASD with preoperative full body images. OUTCOME MEASURES: Horizontal distance between vertebra centroid and ankle.
METHOD(S): Surgical ASD patients were enrolled into a prospective study based on three criteria deformity severity (PI-LL>25degree, TPA>30degree, SVA>15cm, TCobb>70degree or TLCobb>50degree), procedure complexity (>12 levels fused, 3CO or ACR) and/or age (>65 and >7 levels fused). Preop full-body images were evaluated and age and PI-adjusted normative values were used to model spine alignment based upon three configurations: COMP (all lower extremity compensatory mechanisms maintained), PARTIAL (removal of ankle dorsiflexion and knee flexion, maintained hip extension), UNCOMP (ankle, knee, and hip compensation eliminated by reset PT to the age and PI norms). The three configurations were compared, and COMP alignment was stratified by TPA percentiles to investigate the offsets from each vertebra to the ankle joint acting as a surrogate of the gravity line in free-standing position.
RESULT(S): A total of 288 patients met inclusion criteria (60+/-15yo, 70.5% female, 27.4+/-5.9 BMI). COMP spine deformity magnitude included PI-LL 15+/-24, TPA 24+/-14, and SVA 65+/-69mm. As the model transitioned from COMP to UNCOMP alignment, the initial posterior translation of the pelvis decreased significantly to an anterior translation vs the ankle (P.Shift 30 to -7.6 mm). This was associated with a decrease in pelvic retroversion (PT 24.1 to 16.1), hip extension (SFA 203 to 200), knee flexion (KA 5.5 to -0.4), and ankle dorsiflexion (AA 5.3 to 3.7). As a result, the anterior malalignment of the trunk significantly increased SVA (65 to 120mm) and G-SVA (C7-Ankle from 36 to 127 mm), leading to a three-fold increase in bending moments sustained by the ankle joint. The stratification of the COMP position by TPA percentiles revealed that as the deformity increases, the vertebrae above T8 translate anteriorly, those below T10 move posteriorly, with the T8-T10 segment remaining ~3cm posterior to the ankle joint independently of the deformity severity.
CONCLUSION(S): Removal of lower limbs' compensation revealed an unsustainable truncal malalignment with a three-fold increase of bending moments at the ankle joints. Combined, lower limb compensations permit "reducing" the SVA by two-fold and the C7-ankle SVA by three-fold. From a mechanical point of view, this compensation permits maintaining the trunk center of mass (T9) at a fixed offset of ~3 cm from the ankle joint. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Surgical intervention has been shown to be an effective treatment modality for adult cervical deformity (CD), yet patient-reported outcomes vary even when patients are optimally realigned. While patients with higher baseline disability have more room for improvement, we propose there may be a threshold beyond which greater disability limits health-related quality of life (HRQL) improvement due to elevated risks and a point of no return. PURPOSE: To assess impact of baseline disability on HRQL outcomes. STUDY DESIGN/SETTING: Retrospective study of prospectively enrolled CD patients in a multicenter CD database. PATIENT SAMPLE: A total of 116 CD patients were included. OUTCOME MEASURES: HRQL, neck disability index (NDI), modified Japanese Orthopaedic Association (mJOA), EuroQol-5 Dimension (EQ5D).
METHOD(S): CD patients with baseline (BL) and 2-year follow-up (2Y) were included. The cohort was ranked into quartiles by baseline NDI, from lowest/best score (Q1) to highest/worst score (Q4). Means comparison tests analyzed differences between disability groups. Multivariate Analyses (MVA) assessed differences in outcomes of interest controlling for covariates including BL deformity, HRQLs, surgical details and complications.
RESULT(S): A total of 116 patients met inclusion criteria (age: 60.97+/-10.45 yrs, BMI: 28.73+/-7.59kg/m², CCI: 0.94+/-1.31). The cohort presented with mean BL cSVA was 38.54 +/- 19.43mm, TS-CL: 37.34 +/- 19.73, and mJOA: 13.62 +/- 2.71. Surgically, patients had an average of 8.44 +/- 3.41 levels fused, with 53.5% of patients undergoing decompression and 48.3% undergoing osteotomy. Mean BL NDI and numerical rating scale (NRS) of the cohort were 48.33 +/- 17.99 and 6.74 +/- 2.48 respectively. Mean BL NDI by disability group was as follows: Q1: 25.04 +/- 8.19, Q2: 41.61 +/- 2.77, Q3: 53.31 +/- 4.32, and Q4: 69.52 +/- 8.35. MVA assessing improvement in NRS neck and NRS back, found significant differences between disability groups (both p=.007). Patients in Q2 demonstrated the greatest improvement in NRS neck at 2 years (-3.93), which was greater than those in Q3 (-1.61, p=.032) and Q4 (-1.41, p=.015). Patients in Q2 demonstrated greater improvement in NRS back at 2 years (-1.71), compared to those in Q4 (+0.84, p=.010). Rates of MCID in NRS neck were also significantly different across disability groups (p=.023). Patients in Q2 met MCID at the highest rates (69.9%) of all groups, higher than those in Q4 (30.3%), p=.039. MVA found patients in Q2 demonstrated the greatest improvement in EQ5D at 2 years (+0.082), compared to Q1 (+0.073), Q3 (+0.022), and Q4 (+0.014), p=.034. Finally, patients in Q2 demonstrated the greatest improvement in mJOA score from baseline (+1.517), p=.042.
CONCLUSION(S): Patients in Q2, with mean baseline NDI of 42, consistently demonstrated the greatest improvement in HRQLs whereas those in Q4, with mean baseline NDI of 70, saw the least improvement. Thus, baseline NDI between 39 and 44 may represent a disability "wweet spot," within which operative intervention maximizes patient reported outcomes. Furthermore, delaying intervention until patients are severely disabled, beyond an NDI of 61, limits benefits of surgical correction in cervical deformity patients. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Previous orthopedic literature has shown that patients with diabetes mellitus (DM) are more likely to develop complications in the postoperative period. To date, however, no study has assessed the specific pre- and postoperative risk factors that may contribute to this association for diabetic patients undergoing adult spinal deformity surgery. PURPOSE: Establish relevant risk factors for postoperative complications in a cohort of diabetic patients undergoing spinal deformity surgery. STUDY DESIGN/SETTING: Single-center retrospective cohort study. PATIENT SAMPLE: A total of 138 patients with DM who underwent spinal deformity surgery at a single academic hospital from 2012-2019. OUTCOME MEASURES: Primary outcomes were the development of any post-operative complications. These complications included the development of neurologic complications, urinary complications, cardiac complications, pulmonary complications, venous thromboembolism (VTE) and surgical site infections (SSI).
METHOD(S): This study is a retrospective cohort review of diabetic patients undergoing spinal deformity surgery, with 5 levels fused at a single academic medical center. Patients' age, BMI, levels fused, pre- and postoperative hemoglobin (Hgb), hematocrit (HCT) and preoperative HbA1C were collected. T-test and chi-square analyses were used to compare relevant outcomes. Significance was set to p<0.05.
RESULT(S): A total of 138 patients with DM met the inclusion criteria and were included in the analysis. Of these, 50.7% of the total cohort developed a postoperative complication within 90 days of the index surgery. Patients who developed postoperative complications were noted to have significantly lower postoperative Hgb (9.82+/-1.46 g/dL vs 10.72+/-1.76 g/dL, p=0.002) postoperative HCT (28.8+/-3.92% vs 32.60+/-4.61%, p<0.001) and significantly greater number of levels fused (9.49+/-3.74 vs 7.47+/-3.16, p=0.001). Diabetic patients who developed cardiac complications had significantly lower postoperative Hgb (9.47+/-1.50 g/dL vs 10.40+/-1.66 g/dL, p=0.021) and HCT (27.87+/-3.16% vs 31.15+/-4.72%, p=0.003) compared with those who did not. Diabetic patients who developed urinary complications were noted to be older on average (72.56+/-8.20 vs 64.43+/-11.70 years, p=0.043), while patients who developed VTE and pulmonary complications were noted to have significantly higher numbers of levels fused (VTE: 14.00+/-3.61 vs 8.37+/-3.51, p=0.007; PC: 10.82+/-4.14 vs 8.29+/-3.49, p=0.025)Finally, diabetic patients who developed a surgical site infection had significantly lower postoperative HCT (26.74+/-3.27% vs 30.86+/-4.64%, p=0.022) than those who did not. Multivariate logistic regression analysis showed that postoperative HCT (OR: 0.765 [0.613-1.098], p=0.001) and number of levels fused (OR: 1.243 [1.084-1.425], p=0.002) were predictive of development of any postoperative complication, when controlled for BMI, age, and and postoperative Hgb. Postoperative HCT was an independent predictor of the development of cardiac complications (OR: 0.827 [0.692-0.989], p=0.037) and SSI (OR: 0.709 [0.528-0.952], p=0.022).
CONCLUSION(S): Postoperative HCT is predictive of the development of postoperative complications in general, and more specifically the development of cardiac complications and surgical site infections. Along with blood-glucose and HbA1C, it should be closely monitored perioperatively in diabetic patients undergoing spinal deformity surgery. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: VBT takes advantage of the Hueter-Volkmann principle, and modulates growth across intervertebral disc spaces with a tensioned tether secured at the lateral aspects of vertebral bodies. Cervical deformity in AIS patients is associated with lower health related quality of life. PSF constructs have been shown to improve cervical deformity, however, to date, these relationships have not been described in patients treated with VBT. PURPOSE: Determine if cervical sagittal alignment parameters following VBT for correction of AIS are similar to what is observed following PSF. STUDY DESIGN/SETTING: Multi-center retrospective cohort study. PATIENT SAMPLE: Patients with AIS that undergo correction surgeries with LIV in the lumbar spine from 2013 to 2021 with pre- and 2-year postop standing full body plain films available. OUTCOME MEASURES: Outcome measures: Age, height, weight, BMI, Risser score, LIV and levels instrumented. Radiographic analysis included pre- and postop C2 to C7 sagittal vertical axis (cSVA), cervical lordosis angle (CL), T1 slope and thoracic kyphosis (TK).
METHOD(S): Measures were compared using independent samples t-tests, significance set at p<0.05.
RESULT(S): A total of 99 patients: 49 VBT and 50 fusions. The VBT cohort Lenke class breakdown is 23% 1A, 13% 1C, 31% 3C; 18% 5C, and 15% 6C, while the PSF cohort consisted of 42% 1A, 6% 1B, 2% 2C, 2% 3B, 12% 3C, 2% 5B, 24% 5C, and 10% 6C. There were no significant differences with regard to patient age or number of levels instrumented. Patients included in the VBT cohort had a lower level of bone maturity as defined by Risser class (1.6+/-0.9 vs 2.6+/-1.8, p=0.001). The VBT cohort had higher baseline cSVA (3.4mm+/-1.6 vs -1.0mm+/-3.1, 0.001) and less CL (-0.6degree+/-18.2 vs 11.6degree+/-12.8, p=0.001) than the fusion cohort. No differences in baseline T1 slope or Thoracic Kyphosis was observed. VBT patients also had higher 2-year cSVA (3.4mm+/-1.4 vs -3.7mm+/-2.1, p=0.001) and less CL (-4.0+/-18.5 vs 7.0+/-12.2, p=0.001) compared to fusion patients. The PSF group had a significantly greater correction in cSVA than the VBT group (2.8mm+/-4.0 vs 0mm+/-1.6, p=0.001). Both groups displayed improvement in radiographic parameters of cervical and thoracic alignment including CL (VBT 3.3degreevs 4.3degree, p=0.74), T1 slope (VBT -4.3degreevs -4.9degree, p=0.81) and TK (VBT -6.1degreevs -3.9degree, p=0.47). After PSM for Lenke classification, 66 patients remained: 33 VBT, 33 PSF. The PSF group continued to demonstrate greater improvement in cSVA than the VBT group (3.2mm+/-3.0 vs -0.3+/-1.8, p=0.001.
CONCLUSION(S): VBT and PSF both improve radiographic parameters of cervical alignment in AIS patients; however, PSF showed greater correction of cSVA at 2-year followup. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Numerous studies have reported the interplay between spinal deformity and pelvis compensatory mechanisms, but little data exist evaluating the contribution of lower extremity compensation (LE) to maintain upright posture. We hypothesis that hip, knee and ankle compensation is proportional to the severity of the spinal deformity and varies by demographics. PURPOSE: Evaluate the association between spinal alignment and lower limbs compensation. STUDY DESIGN/SETTING: Multicenter, prospective cohort. PATIENT SAMPLE: This study included 288 patients treated for complex adult spinal deformity (ASD) with full body images available. OUTCOME MEASURES: Pelvic retroversion (PT), hip extension (SFA), knee flexion (KA), ankle dorsiflexion (AA), pelvic translation (P.Shift) and patient reported outcomes (ODI, PROMIS and SRS-22).
METHOD(S): Surgical ASD patients were enrolled into a prospective study based on three criteria: deformity severity (PI-LL>25degree, TPA>30degree, SVA>15cm, TCobb>70degree or TLCobb>50degree), procedure complexity (>12 levels fused, 3CO or ACR) and/or age (>65 and >7 levels fused). Associations between lower extremity compensation (hip extension, knee flexion, and ankle dorsiflexion) and the magnitude of spinal deformity, patient demographics, patient frailty, and patient-reported outcomes (ODI, SRS, PROMIS-CAT) were assessed via regressions and partial correlations.
RESULT(S): A total of 288/329 patients met inclusion criteria (60+/-15yo, 70.5% female), had moderate to severe spinal deformity (PI-LL:15+/-24, TPA:24+/-14, SVA:65+/-69mm, lumbar Cobb:34+/-24), and reported high pain (PROMIS pain interference; PI=62.7+/-7.8) and reduced physical function (PROMIS physical function; PF=35.6+/-7.6). Lower extremity compensation included pelvic retroversion (PT:24.1+/- 11.8), hip extension (SFA: 203+/-10.5), knee flexion (KA:5.5+/- 9.6), ankle dorsiflexion (AA: 5.3+/-4.5), and posterior pelvic translation (P.Shift: 30+/-51mm). Overall, lower extremity compensation increased with age (all p <0.001), BMI and frailty (all p <0.001, except SFA). For a similar PT, women had greater hip extension than men (SFA: 206 vs 200, p <0.001), with less KA (3.6 vs. 10.1, p <0.001), AA, and P.Shift. Lower extremity compensation increased with PI (r=0.2-0.45, p <0.001), TPA (r=0.5-0.9, p <0.001) and correlated with PROMS (ODI:0.26 - 0.37, PROMIS PF: -0.28 - -0.39, SRS Acti.: -0.20 - -0.33). When controlling for deformity severity and PI, most associations between lower limbs compensation and PROMS were lost. However, P.Shift and SFA remained weakly correlated with physical scores (ODI and PROMIS PF).
CONCLUSION(S): The recruitment of LE compensation is overall proportional to the severity of adult spinal deformity, with different patterns observed between men and women. Patients achieved similar PT by recruiting different patterns of LE compensation. Hip extension and posterior pelvic translation are independently associated with impairment in patient-reported outcomes. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Previous literature has demonstrated the advantages of lateral single position surgery (L-SPS) in the perioperative period; however, 2-year postoperative outcomes of this novel technique have not yet been compared to circumferential anterior-posterior fusion (FLIP) at 2-years postoperatively. PURPOSE: Evaluate the feasibility and safety of L-SPS technique against the conventional FLIP. STUDY DESIGN/SETTING: Multi-center retrospective cohort study. PATIENT SAMPLE: Patients undergoing primary AP (ALIF or LLIF) fusions with bilateral percutaneous pedicle screw fixation between L2-S1 with minimum 2-year followup at three institutions. OUTCOME MEASURES: Outcome measures included levels fused, operative time, estimated blood loss and perioperative complications. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), PI-LL mismatch and segmental lumbar lordosis.
METHOD(S): Patients were grouped as L-SPS if anterior and posterior portions of the procedure were performed in the lateral decubitus position, and FLIP if patients were repositioned from supine or lateral to prone position for the posterior portion of the procedure. Groups were compared in terms of demographics, intraoperative, perioperative and radiological outcomes, complications and reoperations up to 2 years follow-up. Measures were compared using independent samples or paired t-tests and chi-squared analyses with significance set at p<0.05.
RESULT(S): A total of 442 pts met inclusion, including 352 L-SPS and 90 FLIP pts. Significant differences were noted in age (62.4 vs. 56.9; p= < 0.001) and smoking status (7% vs. 16%; p=0.023) between the L-SPS and FLIP groups. No differences between L-SPS and FLIP were noted in gender (57.4% female vs 57.8% female, p=1.000), BMI (30.0kg/m2 vs 29.3kg/m2; p=0.318). No differences were noted in number of levels fused between L-SPS and FLIP (1.45vs 1.50; p=0.533), proportion including ALIF (38% vs 39%; p=0.809), or the proportion of surgeries including L5-S1 (38%vs 31%; p=0.222). Perioperative outcomes: L-SPS demonstrated significantly lower Op time (97.7min vs 297.0 min; p < 0.001), fluoro dose (36.5mGy vs 78.8mGy; p < 0.001), EBL (88.8mL vs 270.0mL; p < 0.001), and LOS (1.91 days vs. 3.61 days; p < 0.001) compared to FLIP. L-SPS also demonstrated significantly fewer post-op complications than FLIP (21.9% vs 34.4%; p=0.013), specifically regarding rates of ileus (0.0% vs 5.6%; p < 0.001). There was no difference in remaining surgical site, neurological, or medical complications between groups. Reoperation: N=no differences in reoperation were noted at 30-day (1.7%L-SPS vs 4.4%FLIP, p=0.125), 90-day (5.1%L-SPS vs 5.6%FLIP, p=0.795) or 2-year follow-up (9.7%L-SPS vs 12.2%FLIP; p=0.441). The most common reason for return to OR was Adjacent Segment Disease, (L-SPS 3.1% vs. FLIP 7.8%; p=0.067). Pseudarthrosis rates were similar between groups (0.0%L-SPS vs. 1.1%FLIP; p=0.204). Radiological Outcomes: no significant differences were noted in rates of radiological fusion (94.3% L-SPS vs 97.8%FLIP; p=0.266) or subsidence (6.9%L-SPS vs 12.2%FLIP; p=0.260). There were no differences noted between L-SPS and FLIP in change in LL from Baseline to 1-year (3.5 vs 2.8; p=0.466) and post-op to 1yr (-0.18 vs -0.51; p=0.777), or in PI-LL from Baseline to 1-year (-3.5 vs -3.2; p=0.835) and from post-op to 1-year (0.71 vs 0.71; 0.998).
CONCLUSION(S): L-SPS improves safety, improves operative efficiency and reduces complications in the perioperative period while maintaining similar efficacy of AP fusion at 2-year followup in treating degenerative lumbar spinal conditions. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Malalignment following adult spinal deformity (ASD) surgery can negatively impact clinical outcomes and increase risk of mechanical complications. Despite improved definition of ideal alignment for ASD surgery and increasingly sophisticated preoperative alignment planning tools, it remains unclear whether the preoperative goals for alignment are actually achieved with surgery. PURPOSE: The objective of this study was to assess whether preoperative goals for sagittal alignment following ASD surgery are consistently achieved. STUDY DESIGN/SETTING: Multicenter, prospective cohort study. PATIENT SAMPLE: Operatively treatedASD patients. OUTCOME MEASURES: Sagittal vertical axis (SVA), pelvic incidence to lumbar lordosis mismatch (PI-LL), T4-T12 thoracic kyphosis (TK).
METHOD(S): From 2018-2021, ASD patients were enrolled into a prospective ASD study based on three criteria: deformity severity (PI-LL>25degree, TPA>30degree, SVA>15cm, TCobb>70degree or TLCobb>50degree), procedure complexity (>12 levels fused, 3CO or ACR), and/or patient age (>65 and >7 levels fused). The operating surgeon documented sagittal alignment goals prior to surgery, including SVA, PI-LL mismatch and TK. Alignment goals were compared with achieved alignment at 6 weeks postop and the overall mean and SD were calculated for the offset (achieved minus goal) for each measure. Goal alignment was considered attained if the offset was within +/-1 SD of the goal. Demographic, surgical and baseline radiographic measures demonstrating significant association with achieving alignment goal on univariate analysis were used for multivariate regression analysis.
RESULT(S): The 266 enrolled patients had a mean age of 61.0 yrs (SD=14.6 yrs) and 68% were women. Mean number of instrumented levels was 13.6 (SD=3.8) and 24% had a 3-column osteotomy (3CO). Mean (SD) offsets were: SVA=-8.5 mm (45.6 mm), PI-LL=-4.6degree (14.6degree), TK=7.2degree (14.7degree), reflecting a tendency to undercorrect SVA and PI-LL relative to goal and to increase TK relative to goal. Surgeons achieved goal alignment (within 1 SD) for SVA, PI-LL, and TK in 74.4%, 71.4%, and 68.8% of cases, respectively. On regression analysis: goal SVA was more likely to be achieved with lower baseline SVA (OR=0.993, 95%CI=0.988-0.997, p=0.001) and greater baseline TK (OR=1.016, 95%CI=1.002-1.031, p=0.029); goal PI-LL was more likely to be achieved with greater patient age (OR=1.021, 95%CI=1.002-1.039, p=0.026) and history of previous TL spine surgery (OR=2.028, 95% CI=1.136-3.621, p=0.017); and goal TK was more likely to be achieved with lower baseline SVA (OR=0.995, 95%CI=0.991-0.999; p=0.014). The proportions of patients with achieved alignment within 1 SD of goal were not significantly different for patients with a UIV above T7 vs those with a UIV at or below T7 for SVA (p=0.20), PI-LL (p=0.49) or TK (p=0.06). Notably, patient-specific rods were used in 21 patients and were not associated with greater achievement of goal alignment for any parameter (p>0.8), with similar tendencies to undercorrect SVA and PI-LL and increase TK (p>0.6).
CONCLUSION(S): Surgeons failed to achieve goal alignment of each sagittal parameter in ~25% of patients operated for ASD, with a tendency to undercorrect SVA and PI-LL and increase TK. Patients at greatest risk tended to be those with more severe baseline deformity. Further advancements are needed to enable more consistent translation of preoperative alignment planning to the operating room. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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