Comparison of 10-year follow-up result of hybrid surgery and anterior cervical discectomy and fusion for the treatment of contiguous three-level cervical degenerative disc diseases: risk factors for heterotopic ossification.

Purpose: To compare the long-term clinical outcomes and radiographic findings between hybrid surgery (HS) and anterior cervical discectomy and fusion (ACDF) for three-level cervical degenerative disc disease (CDDD). And the incidence, prognosis, and potential risk factors of heterotopic ossification (HO) more than 10 years after Bryan prosthesis replacement in HS has been explored.

Methods: From January 2007 to December 2014, a total of 46 patients who underwent either HS (n = 26) or ACDF (n = 20) for consecutive three-level CDDD were retrospectively analyzed. Clinical outcomes were assessed using the Visual Analogue Scale (VAS), Japanese Orthopaedic Association (JOA) score, and Neck Disability Index (NDI). Radiographic evaluations included cervical lordosis (CL), C2-7 range of motion (C2-7 ROM), ROM of surgical segments (SROM), and adjacent segment degeneration (ASD). Potential risk factors for HO development at the 10-year follow-up after HS, including age, sex, ossification of the anterior longitudinal ligament (OALL), and anterior vertebral osteophytes (AVO), were evaluated. Univariate analysis was followed by multivariate logistic regression to identify independent predictors. Receiver operating characteristic (ROC) curve analysis was performed to determine the predictive value of AVO for HO, including the area under the curve (AUC) and cutoff value. Spearman correlation was used to assess the relationship between ROM and ASD. Postoperative complications were also recorded.

Results: The mean follow-up duration was 141.85 ± 17.20 months. Both groups demonstrated significant improvements in VAS, JOA, and NDI scores at 3 days postoperatively and at the final follow-up compared to preoperative values (P < 0.05). However, there were no statistically significant differences in these scores between the groups at any time point (P > 0.05). At the final follow-up, the HS group exhibited significantly greater C2-7 ROM and SROM compared to the ACDF group (P < 0.05). Both groups showed significant improvement in CL at postoperative day 3 compared to preoperative measurements (P < 0.05). At the 10-year follow-up, the incidence of ASD was lower in the HS group (53.85%) than in the ACDF group (75.00%), with a significant reduction in ASD severity (P < 0.05). A negative correlation between ROM and ASD was observed (P < 0.05). The rate of secondary surgeries was lower in the HS group (0% vs. 5.0%), though the difference was not statistically significant (P > 0.05). The overall prevalence of HO in the HS group was 26.92% (grades I-IV). Both sex and AVO were significantly associated with HO development, and multivariate analysis identified AVO as an independent risk factor (P < 0.05, β = 3.137). ROC curve analysis revealed that AVO had an AUC of 0.85 in predicting HO, with a cutoff value of 1.5.

Conclusions: Both HS and ACDF demonstrated favorable long-term clinical outcomes and effective reconstruction of cervical physiological curvature. However, HS better preserved cervical ROM. At the 10-year follow-up, HS demonstrated a trend toward a lower incidence of ASD compared to ACDF, and reduced the severity of progression of ASD. There was a trend toward fewer reoperation rates in HS. AVO proliferation was identified as a significant independent risk factor for HO after HS, whereas island-type OALL was not significantly associated with HO development. In clinical practice, preoperative evaluation of AVO in ACDR segments is essential to mitigate the risk of postoperative HO formation.