Abstract
An often neglected component of sagittal balance in adolescent idiopathic scoliosis (AIS) is the cervical spine. The cervical spine is capable of compensating for large sagittal deformities by altering head position, but in doing so may give rise to symptoms when the extremes of cervical compensatory mechanisms are reached. This paper seeks to define whether AIS patients have a different cervical lordosis pre and post corrective surgery when compared to normal adolescents.
A review of the literature was carried out in order to define normal cervical lordosis in adolescents. A retrospective analysis of 81 patients with a confirmed diagnosis of idiopathic scoliosis who had received corrective surgery was carried out, and pre and post op cervical lordosis of C1– C7 and C2– C7 were independently measured and recorded using full length sagittal spine radiographs. This data was compared to the 95% confidence interval (95% CI) of cervical lordosis in controls to show if AIS patients showed different cervical spine lordosis before or after corrective surgery.
A literature search showed that normal cervical spine lordosis values are poorly described. However, some values have been published. One study (paper A) gives values of −16° (95%CI −12–20°) for male C2– C7 lordosis and −15° (95% CI −12.5–17.5°) for female C2– C7 adolescents. Another reference (paper B) gives values of −8.4 (95%CI −6.7–10.1°) for male and −1.9 (95%CI −0.5–3.3°) for female adolescents for the same C2– C7 measurements. Our values for male patients for pre op C2– C7 lordosis was −1.2 (95%CI −8.5–6.1°) and 9° (95%CI 2.9– 15.1°) for females. Post op values were 10.6° (95%CI 2.4–18.8°) for males and 8.3° (95%CI 4.8–11.8°) for females.
The values of cervical lordosis in our series show that patients with AIS have a significantly different cervical lordosis when compared to normal values both pre and post deformity correction (p < 0.05). A complete understanding of how the cervical spine is positioned prior to surgery is critical, as flattening the thoracic spine during corrective surgery could give rise to cervical pain and sagittal imbalance if the ability of the cervical spine to compensate for the new spinal position is exceeded.
