Classification

Type 1 is characterized by spondylolysis or listhesis (< 50%), and the following pelvic morphology:

• Low pelvic incidence (< 45°).
• Both pelvis and spine are in balance.
• There is no lumbosacral kyphosis.

Type 2 is characterized by listhesis (< 50%), and the following pelvic morphology:

• Normal pelvic incidence (45-60°).
• Both pelvis and spine are in balance.
• There is no lumbosacral kyphosis.

Type 3 is characterized by < 50% listhesis, and the following pelvic morphology:

• High pelvic incidence ≥ 60°
• Both pelvis and spine are in balance
• There is no lumbosacral kyphosis

Type 4 is characterized by ≥ 50% listhesis, and the following pelvic morphology:

• High pelvic incidence ≥ 60°
• Both pelvis and spine are in balance
• There is no lumbosacral kyphosis

Type 5 is characterized by ≥ 50% listhesis, and the following pelvic morphology:

• High pelvic incidence ≥ 60°
• Retroverted pelvis and a balanced spine
• There may be lumbosacral kyphosis requiring reduction

Type 6 is characterized by ≥ 50% listhesis, and the following pelvic morphology:

• High pelvic incidence ≥ 60°.
• Retroverted pelvis and an unbalanced spine.
• There is lumbosacral kyphosis requiring reduction.