Factors which predict adverse events following surgery in adults with cervical spinal deformity

Lower Hounsfield Units at the Planned Lowest Instrumented Vertebra is an Independent Risk Factor for Complications Following Adult Cervical Deformity Surgery

BACKGROUND

The association of Hounsfield units (HU) and junctional pathologies in adult cervical deformity (ACD) surgery has not been elucidated.

OBJECTIVE

Assess if the bone mineral density of the LIV, as assessed by HUs, is prognostic for the risk of complications after ACD surgery.

STUDY DESIGN/SETTING

Retrospective cohort study.

METHODS

HUs were measured on preoperative CT scans. Means comparison test assessed differences in HUs based on the occurrence of complications, linear regression assessed the correlation of HUs with risk factors, and multivariable logistic regression followed by a conditional inference tree derived a threshold for HUs based on the increased likelihood of developing a complication.

RESULTS

In all, 107 ACD patients were included. Thirty-one patients (29.0%) developed a complication (18.7% perioperative), with 20.6% developing DJK and 11.2% developing DJF. There was a significant correlation between lower LIVs and lower HUs (r=0.351, P=0.01), as well as age and HUs at the LIV. Age did not correlate with change in the DJK angle (P>0.2). HUs were lower at the LIV for patients who developed a complication and an LIV threshold of 190 HUs was predictive of complications (OR: 4.2, [1.2-7.6]; P=0.009).

CONCLUSIONS

Low bone mineral density at the lowest instrumented vertebra, as assessed by a threshold lower than 190 Hounsfield units, may be a crucial risk factor for the development of complications after cervical deformity surgery. Preoperative CT scans should be routinely considered in at-risk patients to mitigate this modifiable risk factor during surgical planning.

LEVEL OF EVIDENCE

Level-III.

Evolution of Adult Cervical Deformity Surgery Clinical and Radiographic Outcomes Based on a Multicenter Prospective Study: Are Behaviors and Outcomes Changing With Experience?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Assess changes in outcomes and surgical approaches for adult cervical deformity surgery over time.

SUMMARY OF BACKGROUND DATA

As the population ages and the prevalence of cervical deformity increases, corrective surgery has been increasingly seen as a viable treatment. Dramatic surgical advancements and expansion of knowledge on this procedure have transpired over the years, but the impact on cervical deformity surgery is unknown.

MATERIALS AND METHODS

Adult cervical deformity patients (18 yrs and above) with complete baseline and up to the two-year health-related quality of life and radiographic data were included. Descriptive analysis included demographics, radiographic, and surgical details. Patients were grouped into early (2013-2014) and late (2015-2017) by date of surgery. Univariate and multivariable regression analyses were used to assess differences in surgical, radiographic, and clinical outcomes over time.

RESULTS

A total of 119 cervical deformity patients met the inclusion criteria. Early group consisted of 72 patients, and late group consisted of 47. The late group had a higher Charlson Comorbidity Index (1.3 vs. 0.72), more cerebrovascular disease (6% vs. 0%, both P <0.05), and no difference in age, frailty, deformity, or cervical rigidity. Controlling for baseline deformity and age, late group underwent fewer three-column osteotomies [odds ratio (OR)=0.18, 95% confidence interval (CI): 0.06-0.76, P =0.014]. At the last follow-up, late group had less patients with: a moderate/high Ames horizontal modifier (71.7% vs. 88.2%), and overcorrection in pelvic tilt (4.3% vs. 18.1%, both P <0.05). Controlling for baseline deformity, age, levels fused, and three-column osteotomies, late group experienced fewer adverse events (OR=0.15, 95% CI: 0.28-0.8, P =0.03), and neurological complications (OR=0.1, 95% CI: 0.012-0.87, P =0.03).

CONCLUSION

Despite a population with greater comorbidity and associated risk, outcomes remained consistent between early and later time periods, indicating general improvements in care. The later cohort demonstrated fewer three-column osteotomies, less suboptimal realignments, and concomitant reductions in adverse events and neurological complications. This may suggest a greater facility with less invasive techniques.

The impact of osteoporosis on adult deformity surgery outcomes in Medicare patients

OBJECTIVE

To identify the impact of osteoporosis (OS) on postoperative outcomes in Medicare patients undergoing ASD surgery.

BACKGROUND

Patients with OP and advanced age experience higher than average rates of ASD. However, poor bone density could undermine the durability of a deformity correction.

METHODS

We queried the MarketScan Medicare Supplemental database to identify patients Medicare patients who underwent ASD surgery from 2007 to 2016.

RESULTS

A total of 2564 patients met the inclusion criteria of this study, of whom n = 971 (61.0%) were diagnosed with osteoporosis. Patients with OP had a similar 90-day postoperative complication rates (OP: 54.6% vs. non-OP: 49.2%, p = 0.0076, not significant after multivariate regression correction). This was primarily driven by posthemorrhagic anemia (37.6% in OP, vs. 33.1% in non-OP). Rates of revision surgery were similar at 90 days (non-OP 15.0%, OP 16.8%), but by 2 years, OP patients had a significantly higher reoperation rate (30.4% vs. 22.9%, p < 0.0001). In multivariate regression analysis, OP increased odds for revision surgery at 1 year (OR 1.4) and 2 years (OR 1.5) following surgery (all p < 0.05). OP was also an independent predictor of readmission at all time points (90 days, OR 1.3, p < 0.005).

CONCLUSION

Medicare patients with OP had elevated rates of complications, reoperations, and outpatient costs after undergoing primary ASD surgery.