Abstract
While cervical lordosis alteration is not uncommon after anterior cervical arthrodesis, its influence on radiological adjacent segment pathology (RASP) is still unclear. Biomechanical changes induced by arthrodesis may contribute to ASP onset. To investigate the correlation between cervical lordosis decrease and RASP onset after anterior cervical corpectomy and fusion (ACCF) and to determine its biomechanical effect on adjacent segments after surgery, 80 CSM patients treated with ACCF were retrospectively studied, and a baseline finite element model of the cervical spine as well as post-operation models with normal and decreased lordosis were established and validated. We found that post-operative lordosis decrease was prognostic in predicting RASP onset, with the hazard ratio of 0.45. In the FE models, ROM at the adjacent segment increased after surgery, and the increase was greater in the model with decreased lordosis. Thus, post-operative cervical lordosis change significantly correlated with RASP occurrence, and it may be of prognostic value. The biomechanical changes induced by lordosis change at the adjacent segments after corpectomy may be one of the mechanisms for this phenomenon. Restoring a well lordotic cervical spine after corpectomy may reduce RASP occurrence and be beneficial to long-term surgical outcomes.
Highlights
Cervical lordosis is a unique morphological characteristic of the cervical spine and may help to optimize the biomechanical loading in this region
After adjustment of confounding factors of age, gender, operation location, fused segment, pre-operative alignment, and operating surgeons, a Cox regression analysis was further performed to evaluate the prognostic value of post-surgical lordotic angle change and the results showed that only the post- surgery C2-7 Cobb angle change was significantly associated with radiological adjacent segment pathology (RASP) onset, with the hazard ratio of 0.454 (Table 3)
The prevalence of RASP was 46.25% in the patients we studied, and the follow-up Japanese Orthopedica Association (JOA) scores were significantly lower in RASP group, though the immediate post-surgery recovery rate (RR) was not significantly different between the 2 groups
Summary
While cervical lordosis alteration is not uncommon after anterior cervical arthrodesis, its influence on radiological adjacent segment pathology (RASP) is still unclear. To investigate the correlation between cervical lordosis decrease and RASP onset after anterior cervical corpectomy and fusion (ACCF) and to determine its biomechanical effect on adjacent segments after surgery, 80 CSM patients treated with ACCF were retrospectively studied, and a baseline finite element model of the cervical spine as well as postoperation models with normal and decreased lordosis were established and validated. Abnormal loading such as vibration, torsion and compression may affect synthetic activity and extracellular matrix molecular expression in the disc[9] Biomechanical loading shifts, such as an increase of segmental range of motion (ROM), intradiscal pressure, and stiffness to adjacent segments after arthrodesis were consistently observed in many experimental and clinical studies[10,11,12,13], and may play an important role in ASP onset. Age Gender(male) Corpectomy C4 C5 C6 C4-5 C5-6 Follow-up period(month) Pre-operative JOA score Post-operative JOA score Follow-up JOA score Post-operative RR(%)
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