TABLE I.

Invasiveness Index Values and Component Scores in Sample Spinal Surgery Procedures

Example	Description of Procedure	Anterior Decompression (ad)	Anterior Fusion (af)	Anterior Instrumentation (ai)	Posterior Decompression (pd)	Posterior Fusion (pf)	Posterior Instrumentation (pi)	Invasiveness Index Value
1	L5-S1 posterior discectomy	No anterior decompression vertebrae (ad = 0)	No anterior arthrodesis vertebrae (af = 0)	No anterior instrumentation vertebrae (ai = 0)	L5 lamina and L5–S1 disc (pd = 1)	No posterior arthrodesis vertebrae (pf = 0)	No posterior instrumentation vertebrae (pi = 0)	1
2	L5-S1 anterior lumbar interbody fusion plating	L5–S1 disc (ad = 1)	L5 and S1 vertebrae (af = 2)	L5 and S1 vertebrae (ai = 2)	No posterior decompression vertebrae (pd = 0)	No posterior arthrodesis vertebrae (pf = 0)	No posterior instrumentation vertebrae (pi = 0)	5
3	T5-T8 posterolateral arthrodesis with pedicle screws and no decompression	No anterior decompression vertebrae (ad = 0)	No anterior arthrodesis vertebrae (af = 0)	No anterior instrumentation vertebrae (ai = 0)	No posterior decompression vertebrae (pd = 0)	T5, T6, T7, T8 vertebrae (pf = 4)	T5, T6, T7, T8 vertebrae (pi = 4)	8
4	L4-L5 posterolateral arthrodesis with L4 and L5 laminectomy and structural graft or cages in the L4-L5 disc space	No anterior decompression vertebrae (ad = 0)	L4 and L5 vertebrae (af = 2)	L4 and L5 vertebrae (ai = 2)	L4 and L5 laminae (pd = 2)	L4 and L5 vertebrae (pf = 2)	L4 and L5 vertebrae (pi = 2)	10
5	T1-ilium posterior; pedicle screws bilaterally at T1, T4, T8, L1, L2, L3, L4, L5, S1, and ilium; laminectomy L1 to S1, and posterior interbody arthrodesis with cages at L1-L2, L2-L3, L3-L4, L4-L5, and L5-S1	No anterior decompression vertebrae (ad = 0)	L1, L2, L3, L4, L5, and S1 vertebrae (af = 6)	L1, L2, L3, L4, L5, and S1 vertebrae (ai = 6)	L1, L2, L3, L4, L5, and S1 laminae (pd = 6)	Twelve thoracic vertebrae (T1–T12), five lumbar vertebrae (L1–L5), S1, and ilium (pf = 19)	T1, T4, T8, L1, L2, L3, L4, L5, S1, ilium (pi = 10)	47