Evaluating Changes to the Modified K-Line Using Kinematic MRIs.

STUDY DESIGN: Retrospective cross-sectional review of a large database. OBJECTIVE: Little is known regarding extension K-lines for treatment of cervical myelopathy. Therefore, this study seeks to examine differences between K-lines drawn in neutral and extension. SUMMARY OF BACKGROUND DATA: The modified K-line is a radiological tool used in surgical planning of the cervical spine. As posterior cervical decompression and fusion often results in patients being fused in a more lordotic position than the preoperative neutral radiograph, a K-line measured in the extension position may offer better utility for these patients. MATERIALS AND METHODS: Total of 97 patients were selected with T2-weighted, upright cervical magnetic resonance imaging taken in neutral and extension. For each patient, the K-line was drawn at the mid-sagittal position for both neutral and extension. The distance from the most posterior portion of each disk (between C2 and C7) to the K-line was measured in neutral and extension and the difference was calculated. Paired t test was used to assess significant differences. RESULTS: Across all levels between C2 and C7 there was an increase in the distance between the dorsal aspect of the disk and K-line when comparing neutral and extension radiographs. The average change in difference (extension minus neutral) at each cervical spinal level was 0.9 mm (C2-C3), 2.5 mm (C3-C4), 2.6 mm (C4-C5), 2.0 mm (C5-C6), and 0.9 mm (C6-C7). A paired t test showed that the K-line increase from neutral to extension was statistically significant across all disk levels ( P <0.001). CONCLUSION: When positioned in extension, patients experience a significant increase in distance from the dorsal aspect of a disk to the K-line compared to when positioned in neutral, especially between C3 and C6. This is clinically relevant for surgeons considering a posterior cervical decompression and fusion in patients with a negative modified K-line on preoperative magnetic resonance imaging, as these patients may have enough cervical cord drift back when fused in an extended position, maximizing likelihood of improving postoperative DSM functional outcomes.

Comparison of Surgical Outcomes Between Anterior and Posterior Cervical Fusions Stratified by Levels Decompressed.

STUDY DESIGN: Retrospective database study. OBJECTIVE: To compare outcomes between 1-, 2-, 3-, and 4- level anterior cervical discectomy and fusions (ACDF) and posterior cervical fusions (PCF) procedures using a national database. SUMMARY OF BACKGROUND DATA: Surgical outcomes involving 3- or 4-level ACDF and PCF cases are not well-described. As there are situations where both ACDF and PCF can be employed, it is important to compare the risks and benefits of both procedures. MATERIALS AND METHODS: Patients who underwent ACDF or PCF between 2010 and 2020 were identified in PearlDiver using current procedural terminology codes. Surgeries done for infectious, traumatic, or neoplastic etiologies were excluded. 2-year reoperations and 90-day readmissions were queried. Surgical complications and transfusions were compiled using ICD-9/10 billing codes. ACDF and PCF procedures were then matched by age, sex, Charlson Comorbidity Index, and a number of levels fused, and the above outcomes were compared. RESULTS: In all, 31,301 PCFs and 110,526 ACDFs were identified. After matching for age, sex, and Charlson Comorbidity Index, a total of 30,353 ACDF and PCF procedures were compared. Three-level and 4-level PCFs had higher rates of 90-day postoperative surgical complications compared with ACDF (OR=2.4 and 2.87, respectively; P <0.001). In addition, higher rates of 90-day readmissions were noted in 3-level PCF compared with 3-level ACDF (OR=1.24, P <0.001). Ninety-day postoperative transfusions were higher in both 3- and 4-level PCFs (OR=2.44 and 18.27, respectively; P <0.001). Two-year reoperations rates were higher for 3-level PCF procedures than 3-level ACDF (OR=1.22; P =0.01). CONCLUSIONS: Patients who underwent 3-4-level ACDF had lower rates of readmission, blood transfusions, and postoperative complications compared with 3-4-level PCF. This data suggests that in cases of 3-4-level pathology with clinical equipoise regarding approach, ACDF may be associated with less short-term morbidity, however, data on fusion rates and adjacent level disease are needed.

Postoperative Complication Rates After One-Level Cervical Spine Surgery in Patients with Parkinson Disease: A Database Study.

OBJECTIVE: Parkinson disease (PD) is a risk factor for worse surgical outcomes. The degree to which PD affects outcomes in cervical spine surgery is not well understood. Therefore, we characterize rates of postoperative complications among patients with PD who undergo cervical spine surgery. METHODS: Using the PearlDiver database, we identified patients who underwent 1-level anterior cervical discectomy and fusion (ACDF), posterior cervical fusion (PCF), or discectomy/decompression with concomitant PD between 2011 and 2019. Patients with PD who underwent surgery and had 1 year follow-up were included. Complications 30, 60, and 90 days after surgery were identified and aggregated into body systems (e.g., respiratory and gastrointestinal). Comparison controls without concomitant PD who received cervical spine (C-spine) surgery were matched for age, sex, and comorbidities. RESULTS: A total of 259,443 ACDFs, 30,929 PCFs, and 29,563 decompressions were identified. Of these procedures, 1117 were performed on patients with PD (0.35%). The highest 90-day complications rates in patients with PD were pulmonary and gastrointestinal related (6.05%) in those who received ACDF, neuro related (8.51%) in those who received PCF, and genitourinary related (8.76%) in those who received a decompression. Compared with patients without PD, postoperative complications rates were similar and not significantly different. CONCLUSIONS: Patients with PD who receive ACDF have higher rates of pulmonary (6.05%), neurologic (5.24%), and psychiatric (3.23%) complications at 90 days. The differences did not reach statistical significance. This finding suggests that patients with PD do not experience higher rates of acute postoperative complications when undergoing 1-level cervical spine surgery.