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Balanced-imbalanced

In the normal population a standard sagittal balance does not exist. We use the upper and lower quartiles to define the gender related variation. As you can see below, the range of Q1-Q3 values overlap the cut-off value of T9-offset = 5.236, between genders. The cut-off value is the value where compensation change direction.

Offset parameters 
The T1 angle is the best predictor of overall sagittal balance, (Knott et al, 2010). The T9 sagittal offset is a significant parameter reflecting several sagittal balance parameters of the spine, (Vialle et al, 2005). Usually, T1 and T9 offset parameters work in harmony to ensure a balanced spine. However, if  T1-9 offset parameters becomes  too pronounced the spine will imbalanced.

Balanced
A balanced  spine is defined by  T9 offset values Q1-Q3  measured in radians.
  • T9 offset male Q1-Q3      5.128 -5.376 radians or ± 7.1°  
  • T9 offset female      Q1- Q3       5.025 - 5.263 radians or ± 6.8°

Imbalanced - Tension Type

An imbalanced spine is defined for T9 offset values above Q3 , gender specific.

  • Hip axis = backwards
  • T1 offset =Thoracic inlet  inclination depressed and in tension
  • Centre of mass = lowered

Imbalanced - Compression type

An imbalanced spine is defined for T9 offset values below Q1, gender specific.
  • Hip axis =  forward
  • T1 offset =Thoracic inlet inclination elevated and in compression
  •  Centre of mass = elevated

The  CTR Sagittal Balance Graph

IN A BALANCED SPINE THE CENTRE OF MASS (CM) IS IN THE T9 LEVEL. IN THE TENSION TYPE CM IS LOWERED AND HIP AXIS IS FORCED BACKWARDS. IN COMPRESSION TYPE CM IS ELEVATED AND HIP AXIS FORCED FORWARDS.

The Sagittal Balance Diagnosis shows the measured balance as a superimposed graph, displayed on a stationary anatomical picture.