Adjacent segment hypermobility after lumbar spine fusion: No association with progressive degeneration of the segment 5 years after surgery

Figures & data

Intervertebral mobility (in mm) and grade of degeneration at the segment adjacent to fusion both before and 5 years after surgery

Case	Level fused	Fusion technique^a	Adjacent segment proximal to fusion	Postoperative mobility for adjacent segment		Z	Postoperative degeneration	Postoperative mobility for adjacent segment		Z	Postoperative degeneration	Increased mobility of adjacent segment?
				X	Y			X	Y
1	L4–S1	U	L3–L4	0.4	1.8	2.4	II	0.7	1.4	2.2	II	No
2	L5–S1	U	L4–L5	0.3	0.6	0.9	I	0.7	0.6	2.4	I	Yes
3	L4–S1	U	L3–L4	0.2	0.8	0.8	I	0.1	0.1	0.6	I	No
4	L4–L5	I	L3–L4	0.3	4.5	3.5	I	0.5	0.4	1.3	I	No
5	L4–S1	I	L3–L4	0.4	1.9	2.6	I	1.9	3.0	4.0	I	Yes
6	L4–L5	I	L3–L4	0.1	0.2	0.1	II	0.1	0.4	0.9	II	Yes
7	L5–S1	A	L4–L5	0.1	0.6	0.8	I	0.1	1.5	2.3	I	Yes
8	L5–S1	A	L4–L5	1.4	3.9	4.5	I	1.2	4.7	6.2	I	Yes
9	L5–S1	A	L4–L5	0.1	0.9	0.8	I	0.6	0.4	0.4	I	No

^a U – Uninstrumented; I – Instrumented; A – Anterior

The Case 1, 3 years after fusion of the L4–S1 level. The patient had relapsing symptoms, but at that time no degeneration of the L2–L3 segment proximal to the segment adjacent to the fusion. Tantalum indicators can be seen placed in L3 and distally.

The same patient 5 years after fusion, with progressive degeneration of the L2–L3 level, where the disc is almost obliterated.