Characterizing utilization patterns and reoperation risk factors of interspinous process devices: analysis of a national claims database.

INTRODUCTION: Interspinous process devices (IPDs) were developed as minimally invasive alternatives to open decompression surgery for spinal stenosis. However, given high treatment failure and reoperation rates, there has been minimal adoption by spine surgeons. This study leveraged a national claims database to characterize national IPD usage patterns and postoperative outcomes after IPD implantation. METHOD: Using the PearlDiver database, we identified all patients who underwent 1- or 2-level IPD implantation between 2010 and 2018. Univariate and multivariable logistic regression was performed to identify predictors of the number of IPD levels implanted and reoperation up to 3 years after the index surgery. Right-censored Kaplan-Meier curves were plotted for duration of reoperation-free survival and compared with log-rank tests. RESULTS: Patients (n = 4865) received 1-level (n = 3246) or 2-level (n = 1619) IPDs. Patients who were older (adjusted odds ratio [aOR] 1.02, 95% confidence interval [CI] 1.01-1.03, P < .001), male (aOR 1.31, 95% CI 116-1.50, P < .001), and obese (aOR 1.19, 95% CI 1.05-1.36, P < .01) were significantly more likely to receive a 2-level IPD than to receive a 1-level IPD. The 3-year reoperation rate was 9.3% of patients when mortality was accounted for during the follow-up period. Older age decreased (aOR 0.97, 95% CI 0.97-0.99, P = .0039) likelihood of reoperation, whereas 1-level IPD (aOR 1.37, 95% CI 1.01-1.89, P = .048), Charlson Comorbidity Index (aOR 1.07, 95% CI 1.01-1.14, P = .018), and performing concomitant open decompression increased the likelihood of reoperation (aOR 1.68, 95% CI 1.35-2.09, P = .0014). CONCLUSION: Compared with 1-level IPDs, 2-level IPDs were implanted more frequently in older, male, and obese patients. The 3-year reoperation rate was 9.3%. Concomitant open decompression with IPD placement was identified as a significant risk factor for subsequent reoperation and warrants future investigation.

Risk Factors for Radiotherapy Failure in the Treatment of Spinal Metastases.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To build a predictive model for risk factors for failure of radiation therapy, hypothesizing a higher SINS would correlate with failure. METHODS: Patients with spinal metastasis being treated with radiation at a tertiary care academic center between September 2014 and October 2018 were identified. The primary outcome measure was radiation therapy failure as defined by persistent pain, need for re-irradiation, or surgical intervention. Risk factors were primary tumor type, Karnofsky and ECOG scores, time to treatment, biologically effective dose (BED) calculations using α/ß ratio = 10, and radiation modality. A logistic regression was used to construct a prediction model for radiation therapy failure. RESULTS: One hundred and seventy patients were included. Median follow up was 91.5 days. Forty-three patients failed radiation therapy. Of those patients, 10 required repeat radiation and 7 underwent surgery. Thirty-six patients reported no pain relief, including some that required re-irradiation and surgery. Total SINS score for those who failed reduction therapy was <7 for 27 patients (62.8%), between 7-12 for 14 patients (32.6%), and >12 for 2 patients (4.6%). In the final prediction model, BED (OR .451 for BED > 43 compared to BED ≤ 43; P = .174), Karnofksy score (OR .736 for every 10 unit increase in Karnofksy score; P = .008), and gender (OR 2.147 for male compared to female; P = .053) are associated with risk of radiation failure (AUC .695). A statistically significant association between SINS score and radiation therapy failure was not found. CONCLUSIONS: In the multivariable model, BED ≤ 43, lower Karnofksy score, and male gender are predictive for radiotherapy failure. SINS score was among the candidate risk factors included in multivariable model building procedure, but it was not selected in the final model. LEVEL OF EVIDENCE: Prognostic level III.

Surgery on the Day of Admission Decreases Postoperative Complication Rates for Patients With Central Cord Syndrome: An Analysis of National Surgical Quality Improvement (NSQIP) Data From 2010 to 2020.

STUDY DESIGN: Retrospective review. OBJECTIVE: This study was undertaken to determine what constitutes "early optimal timing" of surgical management of central cord syndrome (CCS) with respect to a reduction of medical complications. SUMMARY OF BACKGROUND DATA: Data varies on the optimal time for surgical treatment of CCS with some studies favoring early intervention and others advocating that surgery can or should be delayed for 2-6 weeks. METHODS: This IRB-approved study was a retrospective cross-sectional review of surgical management outcomes for patients diagnosed with CCS using the National Surgical Quality Improvement Program database, which consists of anonymized medical record data from the year 2010 to 2020. Patient data included age, sex, American Society of Anesthesiologists score, current procedural terminology codes, length of stay, and postoperative complications. Patients were grouped into admission-day surgery, next-day surgery, and late-surgery groups. RESULTS: A total of 738 patients who underwent surgery to treat CCS were identified in the National Surgical Quality Improvement Program database from 2010 to 2020 and included in this study. Admission-day surgery compared with next-day surgery was associated with a decreased postoperative complication rate after multivariate analysis (odds ratio: 0.52; 95% CI: 0.28-0.97; P =0.0387) as well as shorter length of stay ( P <0.0001). Complication rates between the next-day-surgery cohort and late-surgery cohort did not differ after multivariate analysis (odds ratio: 1.02; 95% CI: 0.63-1.65; P =0.9451), but the length of stay was shorter for next-day surgery ( P <0.0001). Two-year rolling averages for the admission-day-surgery rate and next-day-surgery rate show a compound annual growth rate of 2.52% and 4.10%, respectively. CONCLUSIONS: In patients admitted for surgical treatment of CCS, those who receive admission-day surgery have significantly reduced 30-day complication rates as well as shorter length of stays. Therefore, we advocate that "early surgery" should be defined as surgery on the day of admission and should occur in as timely a manner as possible. Prior studies, which define "early surgery" as within 24 hours might, unfortunately, fall short of reaching the optimal threshold for the reduction of 30-day medical complications associated with the treatment of patients with CCS.

Utilization of Vertebroplasty/Kyphoplasty in the Management of Compression Fractures: National Trends and Predictors of Vertebroplasty/Kyphoplasty.

OBJECTIVE: The purpose of this study is to examine the utilization of kyphoplasty/vertebroplasty procedures in the management of compression fractures. With the growing elderly population and the associated increase in rates of osteoporosis, vertebral compression fractures have become a daily encounter for spine surgeons. However, there remains a lack of consensus on the optimal management of this patient population. METHODS: A retrospective analysis of 91 million longitudinally followed patients from 2016 to 2019 was performed using the PearlDiver Patient Claims Database. Patients with compression fractures were identified using International Classification of Disease, 10th Revision codes, and a subset of patients who received kyphoplasty/vertebroplasty were identified using Common Procedural Terminology codes. Baseline demographic and clinical data between groups were acquired. Multivariable regression analysis was performed to determine predictors of receiving kyphoplasty/vertebroplasty. RESULTS: A total of 348,457 patients with compression fractures were identified with 9.2% of patients receiving kyphoplasty/vertebroplasty as their initial treatment. Of these patients, 43.5% underwent additional kyphoplasty/vertebroplasty 30 days after initial intervention. Patients receiving kyphoplasty/vertebroplasty were significantly older (72.2 vs. 67.9, p < 0.05), female, obese, had active smoking status and had higher Elixhauser Comorbidity Index scores. Multivariable analysis demonstrated that female sex, smoking status, and obesity were the 3 strongest predictors of receiving kyphoplasty/vertebroplasty (odds ratio, 1.27, 1.24, and 1.14, respectively). The annual rate of kyphoplasty/vertebroplasty did not change significantly (range, 8%-11%). CONCLUSION: The majority of vertebral compression fractures are managed nonoperatively. However, certain patient factors such as smoking status, obesity, female sex, older age, osteoporosis, and greater comorbidities are predictors of undergoing kyphoplasty/vertebroplasty.

Surgical Management of Type II Displaced Dens Fractures Improves One-year Mortality in Elderly Patients.

STUDY DESIGN: Retrospective cross-sectional analysis of US national data collected by PearlDiver Inc. database. OBJECTIVE: To determine the rates of surgical/nonsurgical treatments and associated one-year mortality for displaced type II dens fractures without neurological deficit. SUMMARY OF BACKGROUND DATA: Existing literature on dens fractures includes small series of patients with highly variable surgical rates. These studies contain insufficient data to determine the benefits of surgical or nonsurgical treatment as surgeon bias in treatment and selection of patients have significant effects on the results. MATERIALS AND METHODS: Displaced type II dens fractures and upper cervical surgeries were identified using their respective International Classification of Diseases, 10th Revision (ICD-10) diagnosis and Current Procedural Terminology (CPT) codes. Inclusion criteria included patients older than 65, diagnosed with a displaced type II dens fracture, absent neurological damage, during the years 2015 to 2018. Age, sex, ICD-10 diagnosis codes, CPT codes, displacement type, and Elixhauser Comorbidity Index scores were obtained through the PearlDiver database. Patient-related variables and one-year mortality associated with surgical versus nonsurgical treatment were compared using univariate χ 2 analysis, odds ratios, and multivariate logistic regression analysis. RESULTS: Among the 5300 patients who met our inclusion criteria, 59% (n=3108) were female, the mean age was 76.6 (±3.9) years old, and the average Elixhauser Comorbidity Index was 7.1 (±4.0). Only 8.3% (n=437) had surgical treatment for the displaced dens fracture. Multivariate logistic regression analysis for one-year mortality showed surgery was associated with decreased one-year mortality in all patients ( z =-6.26; P <0.001), patients between the ages of 65 and 74 ( z =-2.53; P =0.012), and patients over the age of 75 ( z =-5.81; P <0.001). CONCLUSION: Despite surgery improving survival in elderly patients with type II dens fractures, surgical management is rarely pursued. Factors that independently increase the likelihood of surgery include younger age, male sex, and posterior displacement. LEVEL OF EVIDENCE: 4.

Proximal Junctional Kyphosis: Inter- and Intraobserver Reliability of Radiographic Measurements in Adult Spinal Deformity.

STUDY DESIGN: Reliability study of radiographic measures of proximal junctional kyphosis (PJK) in patients with adult spinal deformity (ASD). OBJECTIVE: To assess impacts of level of proximal endpoint and vertebral fracture on reliability of measurement of junctional kyphosis. SUMMARY OF BACKGROUND DATA: Radiographic assessment is important in determining management of patients with PJK or proximal junctional failure (PJF). No study to date has evaluated the reliability of radiographic measurement of the junctional kyphotic angle after surgery for ASD. METHODS: Postoperative radiographs from 52 patients with ASD were divided into four categories based on the level of the upper instrumented vertebra (UIV) and the presence or absence of PJF: upper thoracic without failure (UT), thoracolumbar without failure (TL), upper thoracic with PJF (UTF), and thoracolumbar with PJF (TLF). Nine surgeon reviewers performed radiographic measurements of kyphosis between UIV+2 and UIV twice at least 4 weeks apart. Intraclass correlation coefficients (ICC) were calculated to determine inter- and intraobserver reliability. RESULTS: Interobserver reliability for measurements of UT, TL, UTF, and TLF were all "almost perfect" with ICC scores of 0.917, 0.965, 0.956, and 0.882, and 0.932, 0.975, 0958, and 0.989, for sessions 1 and 2, respectively. Similarly, ICCs for kyphosis measurements for the TL and TLF group had "almost perfect" agreement with means of 0.898 (range: 0.817-0.969) and 0.976 (range: 0.931-0.995), respectively. ICCs for measurements for the UT and UTF groups all had "substantial" or "almost perfect" agreement with means of 0.801 (range: 0.662-0.942) and 0.879 (range: 0.760-0.988), respectively. CONCLUSION: The present study demonstrates high inter- and intraobserver reliability of PJK measurement following instrumented fusion for ASD, independent of the presence or absence of PJF. Although slightly lower for upper thoracic than for thoracolumbar proximal endpoints, all ICCs consistently reached at least "substantial agreement" and "near perfect agreement" for most. LEVEL OF EVIDENCE: 4.

Differentiation of Murine Bone Marrow-Derived Smooth Muscle Progenitor Cells Is Regulated by PDGF-BB and Collagen.

Smooth muscle cells (SMCs) are key regulators of vascular disease and circulating smooth muscle progenitor cells may play important roles in vascular repair or remodelling. We developed enhanced protocols to derive smooth muscle progenitors from murine bone marrow and tested whether factors that are increased in atherosclerotic plaques, namely platelet-derived growth factor-BB (PDGF-BB) and monomeric collagen, can influence the smooth muscle specific differentiation, proliferation, and survival of mouse bone marrow-derived progenitor cells. During a 21 day period of culture, bone marrow cells underwent a marked increase in expression of the SMC markers α-SMA (1.93 ± 0.15 vs. 0.0008 ± 0.0003 (ng/ng GAPDH) at 0 d), SM22-α (1.50 ± 0.27 vs. 0.005 ± 0.001 (ng/ng GAPDH) at 0 d) and SM-MHC (0.017 ± 0.004 vs. 0.001 ± 0.001 (ng/ng GAPDH) at 0 d). Bromodeoxyuridine (BrdU) incorporation experiments showed that in early culture, the smooth muscle progenitor subpopulation could be identified by high proliferative rates prior to the expression of smooth muscle specific markers. Culture of fresh bone marrow or smooth muscle progenitor cells with PDGF-BB suppressed the expression of α-SMA and SM22-α, in a rapidly reversible manner requiring PDGF receptor kinase activity. Progenitors cultured on polymerized collagen gels demonstrated expression of SMC markers, rates of proliferation and apoptosis similar to that of cells on tissue culture plastic; in contrast, cells grown on monomeric collagen gels displayed lower SMC marker expression, lower growth rates (319 ± 36 vs. 635 ± 97 cells/mm2), and increased apoptosis (5.3 ± 1.6% vs. 1.0 ± 0.5% (Annexin 5 staining)). Our data shows that the differentiation and survival of smooth muscle progenitors are critically affected by PDGF-BB and as well as the substrate collagen structure.

Intrathoracic Glenohumeral Dislocation without Fracture of the Humerus: A Case Report and Review of the Literature.

CASE: A fifty-three-year-old man presented with an intrathoracic glenohumeral dislocation (ITGHD) and associated hemothorax, rib fracture, massive rotator cuff tear, and axillary nerve palsy following an ice hockey injury. Treatment consisted of closed reduction and staged open rotator cuff repair. Despite a substantial injury, the patient recovered nearly normal use of the arm two years postoperatively. CONCLUSION: ITGHD is an extremely rare entity. This injury should be managed by a multidisciplinary team with anticipation of associated thoracic and vascular injuries. In cases with repairable pathology (e.g., an acute rotator cuff tear), good functional outcomes can be obtained.