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Paul A. Anderson and Brett A. Freedman

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Paul A. Anderson, Brett A. Freedman, Dean Chou and Timothy Witham

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Jeffery D. St. Jeor, Taylor J. Jackson, Ashley E. Xiong, Aamir Kadri, Brett A. Freedman, Arjun S. Sebastian, Bradford L. Currier, Ahmad Nassr, Jeremy L. Fogelson, Kurt A. Kennel, Paul A. Anderson and Benjamin D. Elder

OBJECTIVE

The goal of this study was to compare different recognized definitions of osteoporosis in patients with degenerative lumbar spine pathology undergoing elective spinal fusion surgery to determine which patient population should be considered for preoperative optimization.

METHODS

A retrospective review of patients in whom lumbar spine surgery was planned at 2 academic medical centers was performed, and the rate of osteoporosis was compared based on different recognized definitions. Assessments were made based on dual-energy x-ray absorptiometry (DXA), CT Hounsfield units (HU), trabecular bone score (TBS), and fracture risk assessment tool (FRAX). The rate of osteoporosis was compared based on different definitions: 1) the WHO definition (T-score ≤ −2.5) at total hip or spine; 2) CT HU of < 110; 3) National Bone Health Alliance (NBHA) guidelines; and 4) “expanded spine” criteria, which includes patients meeting NBHA criteria and/or HU < 110, and/or “degraded” TBS in the setting of an osteopenic T-score. Inclusion criteria were adult patients with a DXA scan of the total hip and/or spine performed within 1 year and a lumbar spine CT scan within 6 months of the physician visit.

RESULTS

Two hundred forty-four patients were included. The mean age was 68.3 years, with 70.5% female, 96.7% Caucasian, and the mean BMI was 28.8. Fracture history was reported in 53.8% of patients. The proportion of patients identified with osteoporosis on DXA, HUs, NBHA guidelines, and the authors’ proposed “expanded spine” criteria was 25.4%, 36.5%, 75%, and 81.9%, respectively. Of the patients not identified with osteoporosis on DXA, 31.3% had osteoporosis based on HU, 55.1% had osteoporosis with NBHA, and 70.4% had osteoporosis with expanded spine criteria (p < 0.05), with poor correlations among the different assessment tools.

CONCLUSIONS

Limitations in the use of DXA T-scores alone to diagnose osteoporosis in patients with lumbar spondylosis has prompted interest in additional methods of evaluating bone health in the spine, such as CT HU, TBS, and FRAX, to inform guidelines that aim to reduce fracture risk. However, no current osteoporosis assessment was developed with a focus on improving outcomes in spinal surgery. Therefore, the authors propose an expanded spine definition for osteoporosis to identify a more comprehensive cohort of patients with potential poor bone health who could be considered for preoperative optimization, although further study is needed to validate these results in terms of clinical outcomes.

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Paul A. Anderson, Aamir Kadri, Kristyn J. Hare and Neil Binkley

OBJECTIVE

The purpose of this investigation was to characterize the bone health in preoperative spine surgery patients. This information will provide a framework to understand the needs and methods for providing bone health optimization in elective spine surgery patients.

METHODS

A retrospective study of 104 patients undergoing bone health optimization was performed. Patients were selected based on risk factors identified by the surgeon and suspected compromised bone health. Evaluation included history and examination, laboratory investigations, and bone mineral density (BMD) at 3 sites (femoral neck, lumbar spine, and radius). Patients’ bone status was classified using WHO criteria and expanded criteria recommended by the National Osteoporosis Foundation (NOF). The 10-year Fracture Risk Assessment Tool (FRAX) scores of the hip and major osteoporotic fracture (MOF) were calculated with and without femoral neck BMD, with spine BMD, and with the trabecular bone score (TBS). Antiresorptive and anabolic agents were provided in accordance with meeting NOF criteria for treatment of osteoporosis.

RESULTS

The mean patient age was 69.0 years, and 81% of patients were female. The mean historical height loss was 5.6 cm, and 54% of patients had a history of fracture. Secondary osteoporosis due to chronic renal failure, inflammatory arthritis, diabetes, and steroid use was common (51%). The mean 25-hydroxy vitamin D was 42.4 ng/ml and was normal in 81% of patients, with only 4 patients being deficient. The mean T-scores were −2.09 (SD 0.71) of the femoral neck, −0.54 (1.71) of the lumbar spine, and −1.65 (1.38) of the distal radius. These were significantly different. The 10-year FRAX MOF score was 20.7%, and that for hip fracture was 6.9% using the femoral neck BMD and was not significantly different without the use of BMD. The FRAX risk-adjusted score using the lumbar spine BMD and TBS was significantly lower than that for the hip. Osteoporosis was present in 32.1% according to WHO criteria compared with 81.6% according to NOF criteria. Antiresorptive medications were recommended in 31 patients and anabolic medications in 44 patients.

CONCLUSIONS

Surgeons can reliably identify patients with poor bone health by using simple criteria, including historical height loss, history of fracture, comorbidities associated with osteoporosis, analysis of available imaging, and calculation of FRAX score without BMD. High-risk patients should have BMD testing and bone health assessment. In patients with osteoporosis, a comprehensive preoperative bone health assessment is recommended and, if warranted, pharmacological treatment should be started.

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Patrick M. Flanigan, Anthony L. Mikula, Pierce A. Peters, Soliman Oushy, Jeremy L. Fogelson, Mohamad Bydon, Brett A. Freedman, Arjun S. Sebastian, Bradford L. Currier, Ahmad Nassr, Kurt A. Kennel, Paul A. Anderson, David W. Polly and Benjamin D. Elder

OBJECTIVE

Opportunistic Hounsfield unit (HU) determination from CT imaging has been increasingly used to estimate bone mineral density (BMD) in conjunction with assessments from dual energy x-ray absorptiometry (DXA). The authors sought to compare the effect of teriparatide on HUs across different regions in the pelvis, sacrum, and lumbar spine, as a surrogate measure for the effects of teriparatide on lumbosacropelvic instrumentation.

METHODS

A single-institution retrospective review of patients who had been treated with at least 6 months of teriparatide was performed. All patients had at least baseline DXA as well as pre- and post-teriparatide CT imaging. HUs were measured in the pedicle, lamina, and vertebral body of the lumbar spine, in the sciatic notch, and at the S1 and S2 levels at three different points (ilium, sacral body, and sacral ala).

RESULTS

Forty patients with an average age of 67 years underwent a mean of 20 months of teriparatide therapy. Mean HUs of the lumbar lamina, pedicles, and vertebral body were significantly different from each other before teriparatide treatment: 343 ± 114, 219 ± 89.2, and 111 ± 48.1, respectively (p < 0.001). Mean HUs at the S1 level for the ilium, sacral ala, and sacral body were also significantly different from each other: 124 ± 90.1, −10.7 ± 61.9, and 99.1 ± 72.1, respectively (p < 0.001). The mean HUs at the S2 level for the ilium and sacral body were not significantly different from each other, although the mean HU at the sacral ala (−11.9 ± 52.6) was significantly lower than those at the ilium and sacral body (p = 0.003 and 0.006, respectively). HU improvement occurred in most regions following teriparatide treatment. In the lumbar spine, the mean lamina HU increased from 343 to 400 (p < 0.001), the mean pedicle HU increased from 219 to 242 (p = 0.04), and the mean vertebral body HU increased from 111 to 134 (p < 0.001). There were also significant increases in the S1 sacral body (99.1 to 130, p < 0.05), S1 ilium (124 vs 165, p = 0.01), S1 sacral ala (−10.7 vs 3.68, p = 0.04), and S2 sacral body (168 vs 189, p < 0.05).

CONCLUSIONS

There was significant regional variation in lumbar and sacropelvic HUs, with most regions significantly increasing following teriparatide treatment. The sacropelvic area had lower HU values than the lumbar spine, more regional variation, and a higher degree of correlation with BMD as measured on DXA. While teriparatide treatment resulted in HUs > 110 in the majority of the lumbosacral spine, the HUs in the sacral ala remained suggestive of severe osteoporosis, which may limit the effectiveness of fixation in this region.

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Teriparatide treatment increases Hounsfield units in the lumbar spine out of proportion to DEXA changes

Presented at the 2019 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Anthony L. Mikula, Ross C. Puffer, Jeffery D. St. Jeor, James T. Bernatz, Jeremy L. Fogelson, A. Noelle Larson, Ahmad Nassr, Arjun S. Sebastian, Brett A. Freedman, Bradford L. Currier, Mohamad Bydon, Michael J. Yaszemski, Paul A. Anderson and Benjamin D. Elder

OBJECTIVE

The authors sought to assess whether Hounsfield units (HU) increase following teriparatide treatment and to compare HU increases with changes in bone mineral density (BMD) as measured by dual-energy x-ray absorptiometry (DEXA).

METHODS

A retrospective chart review was performed from 1997 to 2018 across all campuses at our institution. The authors identified patients who had been treated with at least 6 months of teriparatide and compared HU and BMD as measured on DEXA scans before and after treatment.

RESULTS

Fifty-two patients were identified for analysis (46 women and 6 men, average age 67 years) who underwent an average of 20.9 ± 6.5 months of teriparatide therapy. The mean ± standard deviation HU increase throughout the lumbar spine (L1–4) was from 109.8 ± 53 to 133.9 ± 61 HU (+22%, 95% CI 1.2–46, p value = 0.039). Based on DEXA results, lumbar spine BMD increased from 0.85 to 0.93 g/cm2 (+9%, p value = 0.044). Lumbar spine T-scores improved from −2.4 ± 1.5 to −1.7 ± 1.5 (p value = 0.03). Average femoral neck T-scores improved from −2.5 ± 1.1 to −2.3 ± 1.0 (p value = 0.31).

CONCLUSIONS

Teriparatide treatment increased both HU and BMD on DEXA in the lumbar spine, without a change in femoral BMD. The 22% improvement in HU surpassed the 9% improvement determined with DEXA. These results support some surgeons’ subjective sense that intraoperative bone quality following teriparatide treatment is better than indicated by DEXA results. To the authors’ knowledge, this is the first study demonstrating an increase in HU with teriparatide treatment.

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Robert F. Heary, Paul A. Anderson and Paul M. Arnold

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Robert F. Heary, Paul A. Anderson and Paul M. Arnold

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Alan H. Daniels, Satoshi Kawaguchi, Alec G. Contag, Farbod Rastegar, Garrett Waagmeester, Paul A. Anderson, Melanie Arthur and Robert A. Hart

OBJECTIVE

Beginning in 2008, the Centers for Medicare and Medicaid Service (CMS) determined that certain hospital-acquired adverse events such as surgical site infection (SSI) following spine surgery should never occur. The following year, they expanded the ruling to include deep vein thrombosis (DVT) and pulmonary embolism (PE) following total joint arthroplasty. Due to their ruling that “never events” are not the payers' responsibility, CMS insists that the costs of managing these complications be borne by hospitals and health care providers, rather than billings to health care payers for additional care required in their management. Data comparing the expected costs of such adverse events in patients undergoing spine and orthopedic surgery have not previously been reported.

METHODS

The California State Inpatient Database (CA-SID) from 2008 to 2009 was used for the analysis. All patients with primary procedure codes indicating anterior cervical discectomy and fusion (ACDF), posterior lumbar interbody fusion (PLIF), lumbar laminectomy (LL), total knee replacement (TKR), and total hip replacement (THR) were analyzed. Patients with diagnostic and/or treatment codes for DVT, PE, and SSI were separated from patients without these complication codes. Patients with more than 1 primary procedure code or more than 1 complication code were excluded. Median charges for treatment from primary surgery through 3 months postoperatively were calculated.

RESULTS

The incidence of the examined adverse events was lowest for ACDF (0.6% DVT, 0.1% PE, and 0.03% SSI) and highest for TKA (1.3% DVT, 0.3% PE, 0.6% SSI). Median inpatient charges for uncomplicated LL was $51,817, compared with $73,432 for ACDF, $143,601 for PLIF, $74,459 for THR, and $70,116 for TKR. Charges for patients with DVT ranged from $108,387 for TKR (1.5 times greater than index) to $313,536 for ACDF (4.3 times greater than index). Charges for patients with PE ranged from $127,958 for TKR (1.8 times greater than index) to $246,637 for PLIF (1.7 times greater than index). Charges for patients with SSI ranged from $168,964 for TKR (2.4 times greater than index) to $385,753 for PLIF (2.7 times greater than index).

CONCLUSIONS

Although incidence rates are low, adverse events of spinal procedures substantially increase the cost of care. Charges for patients experiencing DVT, PE, and SSI increased in this study by factors ranging from 1.8 to 4.3 times those for patients without such complications across 5 common spinal and orthopedic procedures. Cost projections by health care providers will need to incorporate expected costs of added care for patients experiencing such complications, assuming that the cost burden of such events continues to shift from payers to providers.