Development of a Novel Cervical Deformity Surgical Invasiveness Index

Peter G. Passias, MD; Samantha R. Horn, BA; Alexandra Soroceanu, MD; Cheongeun Oh, PD; Tamir Ailon, MD; Brian J. Neuman, MD; Virginie Lafage, PhD; Renaud Lafage, MS; Justin S. Smith, MD; Breton Line, BS; Cole A. Bortz, BA; Frank A. Segreto, BS; Avery Brown, BS; Haddy Alas, BS; Katherine E. Pierce, BS; Robert K. Eastlack, MD; Daniel M. Sciubba, MD; Themistocles S. Protopsaltis, MD; Eric O. Klineberg, MD; Douglas C. Burton, MD; Robert A. Hart, MD; Frank J. Schwab, MD; Shay Bess, MD; Christopher I. Shaffrey, MD; Christopher P. Ames, MD

Disclosures

Spine. 2020;45(2):116-123. 

In This Article

Results

Study Sample

Eighty-five CD patients with complete baseline demographic, clinical, and surgical details and 1-year data were included (61.35 ± 10.66 years, 65.9% female, Table 1). 40% of patients had a prior cervical spine surgery. 31.7% of patients had depression, 15.3% had osteoporosis, and 32.1% had a history of smoking. This cohort had an average of 7.65 levels fused, with 17.6% anterior-only surgeries, 49.4% posterior-only, and 32.9% combined approach. Average length of postoperative hospital stay was 6.35 days, average EBL was 852.19 mL, and average operative time was 373.37 minutes. Baseline radiographic alignment parameters were also assessed, with the cohort having an average PI-LL of 1.25°, SVA of 4.91 mm, TS-CL of 37.02°, cSVA of 46.08 mm, and C2 slope of 38.67° (Table 2). Using the ASD surgical invasiveness index developed by Neuman et al (without the few surgical variables that are ASD-specific), we found that this index explained little of the variability in EBL (R 2 = 0.20), operative time (R 2 = 0.01), and length of hospital stay (R 2 = 0.03).

Newly Developed CD-specific Invasiveness Index

The variables included in the newly developed CD invasiveness index with their corresponding weightings were: history of previous cervical surgery (3), anterior cervical discectomy and fusion (ACDF) (2 per level), corpectomy (4 per level), levels fused (1 per level), implants (1 per level), posterior decompression (2 per level), Smith-Peterson osteotomy (2 per level), three-column osteotomy (8 per level), fusion to upper cervical spine (2), absolute change in TS-CL, cSVA, T4-T12 thoracic kyphosis (TK), and SVA from baseline to 1-year follow-up (Table 3).

CD Surgical Invasiveness Index Predicting LOS, Operative Time, and EBL

The newly developed CD-specific invasiveness index strongly predicted a hospital LOS >5 days (R 2 = 0.310, P < 0.001), high blood loss (R 2 = 0.170, P = 0.011), and extended operative time (R 2 = 0.207, P = 0.031).

Predictive Model for Best Combination of Invasiveness Factors to Predict Outcomes

A second analysis was conducted using multivariable regression modeling to determine which combination of these factors included in the newly developed index were the strongest determinants of operative time, LOS, and EBL. The final predictive model included the following factors: number of corpectomies, levels fused, decompression, combined approach, and absolute changes in SVA, cSVA, and TK. This model predicted EBL (R 2 = 0.26), operative time (R 2 = 0.12), and LOS (R2 = 0.13).

Case Examples

Figure 2 presents pre- and 1-year postoperative radiographs for patient one who underwent an uncomplicated C3-C7 anterior cervical decompression and fusion with posterior spinal fusion from C3-T4. Their score based on the Mirza et al's invasiveness index was 29, 85.3 for the Neuman et al's ASD invasiveness index, and 30.9 when using the newly developed CD invasiveness index. The EBL was 300 mL, operative time was 277 minutes, and LOS 6 days.

Figure 2.

Pre- and 1-year postoperative radiographs of a patient who underwent an uncomplicated C3-C7 anterior cervical decompression and fusion with posterior spinal fusion from C3-T4.

Figure 3 presents pre- and 1-year postoperative radiographs for patient two who underwent an uncomplicated C3–7 anterior cervical decompression and fusion, as well as a C2-T2 posterior spinal fusion with laminectomy. Their score based on the Mirza et al's invasiveness index was 28, 83.0 based on the Neuman et al's ASD invasiveness index, and 203.72 based on the CD invasiveness index. The EBL was 1000 mL, operative time 386 minutes, and LOS 9 days.

Figure 3.

Pre- and 1-year postoperative radiographs of a patient who underwent an uncomplicated C3–7 anterior cervical decompression & fusion, as well as a C2-T2 posterior spinal fusion with laminectomy.

Figure 4 presents the pre- and 1-year postoperative radiographs for patient three who underwent an uncomplicated C6-C7 anterior cervical decompression and fusion, with a C2-T2 posterior spine fusion with a Smith-Peterson osteotomy at the cervicothoracic junction. Their score based on the Mirza et al's invasiveness index was 17, 53.6 based on the Neuman et al's ASD invasiveness index, and 200.42 based on the CD invasiveness index. The EBL was 600 mL, operative time was 567 minutes, and LOS was 6 days. The CD invasiveness scoring can be seen Table 4.

Figure 4.

Pre- and 1-year postoperative radiographs of a patient who underwent an uncomplicated C6-C7 anterior cervical decompression and fusion, with a C2-T2 posterior spine fusion with a Smith-Peterson osteotomy at the cervicothoracic junction.

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