Faculty Bibliography

Advanced age and other comorbid factors correlate with age-increased morbidity associated with spine surgery. It is crucial that spine surgeons critically assess perioperative risks versus postoperative benefits of spine surgery in the growing elderly population. Close coordination between the surgeon, anesthesia team and the patient can minimize complications, improve function and contribute to decreased costs of these complex procedures.

Background/UNASSIGNED:Optimal acetabular component orientation in total hip arthroplasty (THA) is a necessity in achieving a stable implant. Although there has been considerable debate in the literature concerning the safe zone, to date, there has not been any review to determine if these references are consistent with the definition applied by Lewinnek et al. in 1978. Therefore, this article aims to examine the available literature in the PubMed database to determine how often a correct reference to the safe zone as defined by Lewinnek was applied to discussions regarding THA. Methods/UNASSIGNED:A search for literature in the PubMed database was performed for articles from 1978 to 2019. Search criteria included terms 'Lewinnek,' 'safe zone,' and 'total hip arthroplasty.' Exclusions included abstract-only articles, non-English articles, articles unrelated to THA, and those lacking full content. Results/UNASSIGNED:A review of literature yielded 147 articles for inclusion. Overall, only 11% (17) cited the Lewinnek article correctly. Forty-five percent (66) of articles referenced measurements in the supine position, 18% (26) referenced other positions, and 37% (55) did not specify. Nineteen percent (28) reported measurements of the acetabular cup orthogonal to the anterior pelvic plane, while 73% (108) did not, and 7% (11) did not specify. Twenty-three percent (34) measured from computed tomography scans instead of other methods. Conclusions/UNASSIGNED:In the discussion of the safe zone regarding THA, only 11% of articles listed are consistent with the definition established by Lewinnek. This warrants further investigation into a consistent application of the term and its implications for THA implant stability and dislocation rates.

The aim of this study was to investigate the cost utility of treating non-frail versus frail or severely frail adult spinal deformity (ASD) patients. 79 surgical ASD patients >18 years with available frailty and ODI data at baseline and 2-years post-surgery (2Y) were included. Utility data was calculated using the ODI converted to the SF-6D. QALYs utilized a 3% discount rate to account for decline to life expectancy (LE). Costs were calculated using the PearlDiver database. ICER was compared between non-operative (non-op.) and operative (op.) NF and F/SF patients at 2Y and LE. When compared to non-operative ASD, the ICER was $447,943.96 vs. $313,211.01 for NF and F/SF at 2Y, and $68,311.35 vs. $47,764.61 for NF and F/SF at LE. Frail and severely frail patients had lower cost per QALY compared to not frail patients at 2Y and life expectancy, and had lower ICER values when compared to a non-operative cohort of ASD patients. While these results support operative correction of frail and severely frail patients, it is important to note that these patients are often at worse baseline disability, which is closely related to frailty scores, and have more opportunity to improve postoperatively. Furthermore, there may be a threshold of frailty that is not operable due to the risk of severe complications that is not captured by this analysis. While future research should investigate economic outcomes at extended follow up times, these findings support the cost effectiveness of ASD surgery at all frailty states.

BACKGROUND: Bone morphogenetic protein (BMP) and allograft containing mesenchymal stem cells (live cell) are popular biologic substitutes for iliac crest autograft used in transforaminal lumbar interbody fusion (TLIF). Use of these agents in the pathogenesis of postoperative radiculitis remains controversial. Recent studies have independently linked minimally invasive (MIS) TLIF with increased radiculitis risk compared to open TLIF. The purpose of this study was to assess the rate of postoperative radiculitis in open and MIS TLIF patients along with its relationship to concurrent biologic adjuvant use. METHODS: Patients ≥18 years undergoing single-level TLIF from June 2012 to December 2018 with minimum 1-year follow-up were included. Outcome measures were rate of radiculitis, intra- and postoperative complications, revision surgery; length of stay (LOS), and estimated blood loss (EBL). RESULTS:= .038, N = 336) compared to other combinations of surgical approach and biologic use. CONCLUSIONS: Neither the MIS approach nor BMP use is an independent risk factor for post-TLIF radiculitis. However, risk of radiculitis significantly increases when they are used in tandem. This should be considered when selecting biological adjuvants for MIS TLIF. LEVEL OF EVIDENCE/METHODS: 3.

Background/UNASSIGNED:Changes in spinopelvic and lower extremity alignment between standing and relaxed sitting have important clinical implications with regard to stability of total hip arthroplasty. This study aimed to analyze the effect of body mass index (BMI) on lumbopelvic alignment and motion at the hip joint. Methods/UNASSIGNED:A retrospective review of patients who underwent full-body stereoradiographs in standing and relaxed sitting for total hip arthroplasty planning was conducted. Spinopelvic parameters measured included spinopelvic tilt (SPT), pelvic incidence (PI), lumbar lordosis (LL), PI minus LL (PI-LL), proximal femoral shaft angle (PFSA), and standing-to-sitting hip range of motion. Propensity score matching controlled for age, gender, PI, and hip ostoarthritis grade. Patients were stratified into normal (NORMAL; BMI, 18.5-24.9), overweight (OW; 25.0-29.9), and obese (OB; 30.0-34.9) groups. Alignment parameters were compared using one-way analysis of variance. Results/UNASSIGNED:< .001). Conclusions/UNASSIGNED:Significant differences in sitting and standing-to-sitting change in lumbopelvic alignment based on BMI suggest obese patients recruit more posterior spinopelvic tilt when sitting to compensate for soft-tissue impingement that occurs anterior to the hip joint and limiting hip flexion.

BACKGROUND CONTEXT: The Patient Reported Outcome Measurement Information System (PROMIS) aims to offer a valid, reliable and efficient means of capturing spine surgery patient clinical outcomes. To date, few studies have compared PROMIS and legacy outcome measures like the Oswestry Disability Index (ODI) for their sensitivity in reflecting the impact of perioperative complications and length of stay. PURPOSE: Assess differences between PROMIS and ODI scores as they relate to length of stay and complication outcomes of surgical thoracolumbar patients. STUDY DESIGN/SETTING: Retrospective review of single institution clinical data and patient-reported outcome measures. PATIENT SAMPLE: A total of 182 patients undergoing thoracolumbar surgery. OUTCOME MEASURES: Length of stay (LOS), perioperative complications.
METHOD(S): Patients >18 years undergoing thoracolumbar surgery with available pre- and 3-month postoperative ODI and PROMIS scores were included. Pearson bivariate correlation assessed the linear relationships between clinical outcomes (including length of stay, complications) and scores for both PROMIS (Physical Function, Pain Intensity, Pain Interference) and ODI. Linear regression predicted the relationship between perioperative complication incidence and postop scores for ODI and PROMIS. Significance was set p<0.05.
RESULT(S): Included: 182 patients (55.2+/-16.1 years, 44.5% female, 29.5+/-6.3 kg/m2) undergoing thoracolumbar surgery. Among the most common diagnoses were stenosis (62.1%), radiculopathy (48.9%), herniated disc (47.8%), and degenerative spondylolisthesis (25.3%). Overall, 58.3% of patients underwent fusion (mean fusion length: 2.6+/-2.9 levels), 50% underwent laminectomy, 82.9% of cases involved posterior-only approach, 17.6% combined, and 0.5% anterior-only. Patients showed significant pre- to postoperative improvement in both ODI (50.2 to 39.0) and PROMIS Physical Function (10.9 to 21.4), Pain Intensity (92.4 to 78.3) and Pain Interference (58.4 to 49.8, all p<0.001). Mean LOS was 2.7+/-2.8 days. The overall complication rate was 16.5%, and by type, complications were most commonly cardiac, neurologic, or urinary (all 2.2%). Whereas LOS showed no relationship with pre- to postop changes in ODI (p=0.179), changes in PROMIS Pain Intensity (r=0.167, p=0.024) and Physical Function (r=-0.169) both correlated with LOS. Complication occurrence was not correlated with pre- to postoperative changes in ODI or PROMIS (all p>0.05); however, 3-month postoperative scores for Physical Function (r=-0.205, p=0.005) and Pain Interference (r=0.182, p=0.014) both showed stronger correlations with complication occurrence than ODI (r=0.143, p=0.055). Regression analysis showed that while perioperative complication incidence could not predict postoperative ODI (p>0.05), complication occurrence predicted Physical Function (R2=0.037, p=0.005) and Pain Interference (R2=0.028, p=0.014) scores.
CONCLUSION(S): The PROMIS domains of Physical Function and Pain Interference better reflected perioperative complications and length of stay as compared to the legacy patient reported outcome ODI. These results suggest PROMIS may offer more utility as an outcomes assessment instrument. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: C5 palsy stands as a known but poorly understood complication of cervical spine surgery with rates reported as high as 30%. Although there are multiple studies presenting different risk factors, variability in findings have led to controversy in the etiology of postoperative C5 palsy. PURPOSE: To evaluate factors that predispose a patient to developing C5 palsy following cervical spine surgery. STUDY DESIGN/SETTING: Retrospective review of a large single center academic institution. PATIENT SAMPLE: This study included 239 cervical spinal procedures from 2013 to 2018. OUTCOME MEASURES: Patient demographics, surgical procedure and approach, perioperative clinical characteristics, postoperative rate of C5 palsy, C5 palsy resolution, and radiographic outcomes.
METHOD(S): Patients >=18 years of age who underwent cervical spinal surgery including the C4/C5 level, with minimum 1-year follow-up were included. C5 palsy was defined as deltoid +/- bicep weakness with Modified Rankin Scale grading at least 1 point below baseline (BL). Characteristics studied include: demographics, surgical procedure and approach (decompression and/or fusion). Radiographic analyses of MRI and CT measurements of foramen dimensions and spinal cord drift at BL and follow-up were performed. Statistical analyses included t-tests, chi-square analysis, and multivariate logistic regression to determine independent predictive factors. A receiver operating characteristic curve was run to determine the cutoff levels for predictive factors. Significance set at p<0.05.
RESULT(S): A total of 239 patients were included, with a C5 palsy rate of 6.3% for all cases. Subjects that developed C5 palsy were older (64.67+/-8.61 vs 57.56+/-11.61, p=0.021), had more levels decompressed posteriorly (3.20+/-1.82 vs 1.12+/-1.74, p<0.001), a higher rate of preoperative myelomalacia (60% vs 19.6%, p=0.008), and higher CCI (3.80+/-1.97 vs 2.35+/-1.95, p=0.005). Anterior cervical discectomy and fusion (ACDF) surgeries had a 2.4% rate of C5 palsy while the posterior approach rate was 11.9% (p<0.007). The highest rate was in laminectomy and posterior fusion at 15.2% (p<0.001). There were no significant differences in palsy resolution between those treated surgically compared to those not treated. Radiographically, C5 palsy patients had smaller postoperative foramen width measurements than those who did not develop C5 palsy (2.16+/-1.04 vs 3.31+/-1.25, p=0.023 on the right; 1.84+/-0.80 vs 3.02+/-1.25, p=0.014 on the left). When controlling for technique, CCI, age, BMI, and myelomalacia, multivariate regression analysis revealed increasing levels of laminectomy to be a significant independent predictor of C5 palsy (1.602 (2.258-1.136) for each additional level decompressed, p=0.007). The cut-off value for levels decompressed via laminectomy was determined to be 3.50 levels (>=0.7 AUC <=0.8). Postoperative foramen width was also an independent risk factor for C5 palsy (0.009 (0.000-0.726), p=0.035), it was determined that risk of C5 palsy increases at <2.625mm foramen width (>=0.8 AUC <=0.9).
CONCLUSION(S): C5 palsy following cervical spine surgery is correlated with residual postoperative foraminal stenosis and posterior surgery with increasing number levels decompressed. Patients undergoing more than 3.5 level laminectomy with less than 2.625mm foramen width postoperatively are at highest risk of developing C5 palsy. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: Adult spinal deformity (ASD) correction involves complex, invasive procedures. However, it is unknown how metabolic syndrome affects the cost efficiency of ASD surgery. PURPOSE: Investigate the differences in ASD surgery cost for metabolic syndrome patients. STUDY DESIGN/SETTING: Retrospective review of a single center ASD database. PATIENT SAMPLE: A total of 557 ASD patients. OUTCOME MEASURES: Complications, revisions and costs.
METHOD(S): ASD patients (scoliosis >=20degree, SVA>=5cm, PT >=25degree, or TK >=60degree) >=18, undergoing >=4 level fusions were included. Descriptive analysis assessed mean baseline demographic, radiographic and surgical data were assessed. Patients diagnosed with: BMI >30, diabetes mellitus, and HTN were classified metabolic syndrome patients (MetS). Independent samples T-tests assessed baseline differences in SVA, PT, PI-LL, and levels fused between MetS and non-MetS patients. Total surgery costs for MetS and non-MetS ASD patients were compared. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims. Complications and comorbidities (CC) and major complications and comorbidities (MCC) were assessed according to CMS.gov manual definitions.
RESULT(S): A total of 557 patients met inclusion criteria. Baseline demographics and surgical details: age 60.8 +/- 13.2, 67.5% female, BMI 28.3 +/- 6.67, 6.2% anterior approach, 81.0% posterior approach, 12.8% combined approach, 10.4 +/- 3.9 levels fused, op time 423.5 +/- 166.4 minutes, EBL 2061.4 +/- 1631.5 cc, LOS 7.6 +/- 5.4 days. 11 MetS patients were included. There was no significant difference in BL SVA (54.2degree vs 70.3degree), PT (26.7degree vs 23.7degree), PI-LL (16.4degree vs 21.2degree), or levels fused between groups (10.5 vs 10.6) (all p>0.05). Twenty-seven percent of MetS patients experienced a CC or MCC, with 18% undergoing revisions within 90 days (vs 13.2% and 3.2% for non-MetS, p<0.05). The average costs of surgery for MetS patients was $68,004.06 vs $48,726.40 for non-MetS patients (p<0.05).
CONCLUSION(S): Metabolic syndrome is a growing concern among health care providers. In metabolic syndrome patients undergoing corrective adult spinal deformity surgery, the total costs of surgery was 28.4% higher for metabolic syndrome patients ($68,004.06 vs $48,726.40). Optimizing modifiable factors like diabetes or BMI in preoperative patients may have an impact on cost effectiveness. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: Frailty is an increasingly recognized characteristic that has been validated across many studies as influencing operative risk. Utilization of frailty indices can allow for its identification of which spine patients may be too high risk for surgical intervention. This may be especially useful when it comes to surgeries that are minimally invasive and are supposed to have decrease perioperative outcomes. PURPOSE: Identify MIS techniques effects in postoperative outcomes in TLIF patients. STUDY DESIGN/SETTING: Retrospective review of a prospective database. PATIENT SAMPLE: TLIF spine patients. OUTCOME MEASURES: Complications, length of stay (LOS), estimated blood loss (EBL).
METHOD(S): Pts that underwent a lumbar spine procedure in a single-center Comprehensive Spine Quality Database. Pts were stratified based on procedural approach (Open [OP] and Minimally invasive Surgery [MIS]). Frailty was then calculated for each resultant group by using 30 variables with a validated method. Based on these scores, pts were categorized no frailty [NF]: <0.09, frail [F]: 0.09-0.18, and severe frailty [SF] >0.18. Groups were then controlled for surgical invasiveness. Chi-squared tests identified the relationship between complications and length of stay among various frailty states given surgical approach (OP vs MIS). These patients were propensity score matched for levels fused. Hospital acquired complications (HACs) were identified based on frailty groups through the use of chi-squared and t-tests for other surgical factors. A logistic regression analysis identified the association between frailty status and surgical, regarding postoperative (postop) outcomes.
RESULT(S): A total of 1,300 TLIF spine patients were isolated (59yrs, 29.3kg/m2). After PSM for levels fused, there were 338 pts for both MIS and OP. MIS pts were older (56.1 vs 53.3; p<0.05) than Op pts and had similar BMI's (29.1 vs 29.7; respectively). However, OP received more posterior approaches and less anterior approaches than MIS pts (p<0.05). By surgical factors: MIS and OP patients had similar LOS (3 vs 2.9days) and EBL (282.8 vs 251.5cc) but differed by Op time (195.7 vs 247.1; p<0.05) respectively. Further breakdown by frailty displayed statistical significance between MIS and OP patients with MIS pts having more F (16% vs 12%) and SF pts (4.3% vs 1.9%) than OP (all p<0.05). FMIS patients had lower postop neurologic complications as compared to FOP pts (4.63% vs 14.8%). However, SFMIS patiens had more post-operative complications than SFOP pts (55.2% vs 23.1%) and increased a pt's likelihood of being SFMIS by 5.4x's (all p<0.05).
CONCLUSION(S): This study displays that when frailty status is taken into account, TLIF MIS patients benefit from this procedure type when analyzed against neurologic complications. However, these patients were seen to suffer more from postop complications but did not differ on any other specific complications or surgical variables. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: The thoracolumbar junction poses increased risk for high stress on upper lumbar discs when not adequately fused. However, controversy persists. This study evaluates outcomes of upper instrumented vertebrae (UIV) selection in the thoracic versus the upper lumbar spine when fusing to the sacrum. PURPOSE: To compare revision rates for thoracolumbar fusions to the sacrum and pelvis at 1- and 2-year follow-up, stratified by UIV selection. STUDY DESIGN/SETTING: Retrospective cohort study at a single institution. PATIENT SAMPLE: A total of 968 patients who had thoracolumbar fusion surgery between 2012-2018 with at least one year of postoperative follow-up. OUTCOME MEASURES: Reoperation rates from 1 and 2 years after revision surgery, reoperation diagnoses, body mass index (BMI), gender, Charleston Comorbidity Index (CCI), perioperative complications, ASA grade (ASA), operative time (OT), and blood loss (EBL).
METHOD(S): A retrospective review of patients undergoing revision spinal fusion with lower instrumented vertebra of S1 or pelvis between 2012-2018 at a single institution was performed. Patients with less than 1 year of follow-up after their index procedure were excluded from the analysis. Patients were categorized based on UIV into 6 groups: T9-T11, L1, L2, L3, L4, and L5. Demographic and operative data were collected and compared between the different UIV groups in each cohort using chi-squared and ANOVA tests. Revision rates at 1- and 2-year follow-up and the reasons for revision were compared between groups.
RESULT(S): There were 168 revision spinal fusions that reached 1-year follow-up, with 54 having UIV at T9-T11, 2 fusions L1 to sacrum, 26 fusions L2 to sacrum, 25 fusions L3 to sacrum, 36 fusions L4 to sacrum, 23 fusions L5 to sacrum. There was significant difference in patient age, with oldest in the L1 group (65.5+/-3.5) and youngest in the L5 group (51+/-15.4 p<0.001). There was significant difference in gender as both cases in L2 was female and L5 fusions only had 39.1% females (p = 0.006). There were no differences in BMI, CCI, and ASA. EBL (1891.6mL+/-1226.9mL p <0.001) and length of stay (7.7+/-3.0 p <0.001) was highest in the T9-11 UIV group. Operative time was highest in the L1 (464.5+/-174.7 p<0.001) UIV group. Levels added on top of prior fusion were calculated by subtracting UIV of index fusion to past UIV. Adding on 2 levels had a 1-year revision rate of 14.3% (p = 0.032), while adding on 1 level had a 0% 1-year revision rate. Adding on 4 levels had a revision rate of 12.5%, and adding on 7 levels had a 50% 1-year revision rate. At 2 years, adding on 1 level had revision rate of 25% and adding on 2 levels had a revision rate of 20% (p = 0.769). There is no statistically significant difference in perioperative complication rates between UIV groups (p = 0.114). The reoperation rate at 1 year for all levels was 9% and highest in UIV at L1 (50%, p=0.06). At 2-year follow-up, the reoperation rate for the total cohort was 32.34% with the highest revision rate for fusion from L2 to sacrum (53.85%) followed by (T9-T11 sacrum fusion 42.31%, L4 to sacrum31.71%, L3 to sacrum 30%, L5 to sacrum 25.04%, L1 to sacrum 25%, p=0.195). Grouping the UIV into lower thoracic (T9-T11), upper lumbar (L2-L3), and lower lumbar (L4-L5) showed similar revision rates at one year (p=0.697). At two years, lower thoracic group had a revision rate of 40% versus, 23.3% in the upper lumbar group (p =0.399).
CONCLUSION(S): There is no statistically significant difference in reoperation rates for revision thoracolumbar fusions to the sacrum/pelvis associated with different UIV selection. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright