Sequential sagittal alignment changes in the cervical spine after occipitocervical fusion.

Area of Science:

• Orthopedics
• Neurosurgery
• Radiology

Background:

• Limited studies exist on sequential changes in upper and lower cervical sagittal alignment post-occipitocervical fusion (OCF).
• No comparative studies have assessed cervical sagittal alignment (CSA) between craniocervical junction disorder (CJD) patients and normal populations.

Purpose of the Study:

• To compare CSA in CJD patients versus controls.
• To investigate sequential CSA changes in the upper and lower cervical spine after OCF.

Main Methods:

• Radiographic parameters (O-C2a, O-EAa, C2-7a, PIA) were measured in 84 OCF patients and 42 controls.
• Pre- and postoperative measurements were compared, and correlations analyzed using Pearson's test.

Main Results:

• OCF patients had smaller occipital to C2 angles (O-C2a) and pharyngeal inlet angles (PIA) but larger occipital and external acoustic meatus to axis angles (O-EAa) and C2-7 angles (C2-7a) than controls.
• No significant changes in O-C2a, C2-7a, or PIA were observed in the OCF group from baseline to final follow-up.
• Significant correlations were found between O-C2a and other parameters (C2Ta, C2-7a, C2-7 SVA, PIA) at 1 month and final follow-up post-OCF.

Conclusions:

• CJD patients present with more kyphotic upper CSA and more lordotic lower CSA compared to controls.
• OCF's effectiveness in restoring CSA may be limited if craniocervical junction realignment is overlooked.
• Reduced O-C2a post-OCF may correlate with increased C2-7a and decreased PIA.