The bisegmental Cobb angle in osteoporotic spine fractures: Does it influence treatment decision or functional...

Osteoporotic vertebral compression fractures (OVCF) represent a growing clinical challenge and the effect of bisegmental Cobb angles in treatment decision and outcome prediction for remains unclear.

This prospective multicenter study analyzed 350 patients with thoracolumbar OVCF (OF2-OF4). Bisegmental Cobb angles (CA) were measured at the day of treatment decision, discharge, and follow-up. Associations with treatment, OF classification, pain, and functional outcomes were analyzed.

Patients treated with instrumentation showed more pronounced kyphotic alignment than conservatively treated patients at baseline (-11 ± 12° vs. -7 ± 14°, p = 0.042). CA correlated weakly with OF-Score (r = -0.167, p = 0.002) and OF classification (r = -0.195, p < 0.001), but not with pain (p = 0.789). ROC analyses demonstrated poor discriminatory power of CA for treatment (AUC = 0.557, p = 0.078); the predefined kyphosis threshold of -15° was not predictive. Multinomial logistic regression confirmed that OF classification (p < 0.001) and pain intensity (p < 0.001), but not CA (p = 0.310), independently predicted the performed treatment. Over time, surgically treated patients achieved significant fracture reduction (-6 ± 7° during hospitalization, p < 0.001) with partial loss at follow-up, whereas conservatively treated patients showed progressive increased kyphosis. CA were not consistently associated with functional outcomes.

The CA alone has limited value for guiding treatment decisions in thoracolumbar OVCF, and fixed angular thresholds are not clinically useful. However, restoration of the segmental sagittal profile appears to be associated with clinical outcome after surgical treatment. For this reason, the bisegmental Cobb angle certainly does not play the main role in the decision on treatment, but it should be included as a secondary parameter.