Sagittal balance: from theory to clinical practice

Abstract

Adequate sagittal balance (SB) is essential to maintain an upright, efficient, and painless posture. It has been shown that sagittal profile alterations affect quality of life of patients with a similar or even greater impact than chronic disease. Evaluation of the SB has gained much relevance in recent years, with recognition of its importance in the evaluation of spinal pathology. This review summarizes the basic principles of SB, aiming to obtain a practical, simple and understandable evaluation of the sagittal profile of a patient. SB is a dynamic process that involves a varying degree of energy expenditure. Distinguishing between a balanced, compensated imbalance or decompensated imbalanced patient, is relevant to diagnosis and therapeutic decision-making.

Fig. 1

Economy cone scheme according to Dubousset.

Fig. 2

Publications registered in PubMed. From 1990 to 2010, 915 publications were registered, while from 2010 onwards the number increased to 2262.

Fig. 3

Clavicle position.

Fig. 4

Cervical lordosis, thoracic kyphosis and lumbar lordosis measurement scheme.

Fig. 5

Measurement of pelvic incidence, pelvic tilt and sacral slope.

Fig. 6

Measurement of C7 plumb line, sacral vertical axis and T1-pelvic angle.

Fig. 7

Relationship of lumbopelvic parameters.

Fig. 8

Morphological types of sagittal profile according to Roussouly.

Fig. 9

Segmental hyperextension as a regional compensatory mechanism.

Fig. 10

Global vision of compensatory mechanisms.

Fig. 11

Balanced patient: PI of 35° and LL of 44°, with an adequate relationship between these (35–44 = –9°) and a neutral SVA with a TPA of 2°, without compensatory mechanisms, PT = 2° and SS = 33° (35° = 2° + 33°). Note. PI, pelvic incidence; LL, lumbar lordosis; SVA, sacral vertical axis; TPA, T1-pelvic angle; PT, pelvic tilt.

Fig. 12

Compensated imbalance patient: PI of 62° and a LL of 50°, showing an alteration between the relationship of these (62–50° = 12°) with a slightly altered TPA of 18°, but with an SVA within normal limits (43 mm), at the expense of compensatory mechanisms such as pelvic retroversion (PT = 21°) and verticalization of the sacrum (SS = 41°). Patients with a high PI have a great capacity for pelvic compensation (62° = 21° + 41°), which will allow you to increase PT even more. Note. PI, pelvic incidence; LL, lumbar lordosis; TPA, T1-pelvic angle; SVA, sacral vertical axis; PT, pelvic tilt; SS, sacral slope.

Fig. 13

Decompensated imbalanced patient: PI of 46° and LL of 22° with severe alteration between them (46–22° = 24°) and an elevated SVA and TPA (130 mm and 27°, respectively) when reaching the physiological limits of pelvic retroversion (PT: 19°) and sacral verticalization (SS: 27°) for his PI (46° = 19° + 27°). Note. PI, pelvic incidence; LL, lumbar lordosis; TPA, T1-pelvic angle; SVA, sacral vertical axis; PT, pelvic tilt; SS, sacral slope.