Table 4. Effects of level and interaction effects level × laminectomy and level × instrumentation on ROM and stiffness.

		Segment level (p value)		Segment level × laminectomy (p value)		Segment level (p value)		Segment level × instrumentation (p value)
	Segments	ROM	Stiffness	ROM	Stiffness	ROM	Stiffness	ROM	Stiffness
FE
Laminectomy	5 × L2–L3 and 6 × L4–L5	0.414	0.665	0.255	0.229	0.626	X	0.545	X
Adjacent	6 × L1–L2 and 6 × L3–L4	0.721	0.448	0.516	0.325	0.864	0.226	0.987	0.959
Control	6 × L2–L3 and 6 × L4–L5	0.707	0.626	0.535	0.279	0.716	0.701	0.883	0.123
LB
Laminectomy	5 × L2–L3 and 6 × L4–L5	0.441	0.780	0.151	0.209	0.594	X	0.467	X
Adjacent	6 × L1–L2 and 6 × L3–L4	0.576	0.291	0.178	0.786	0.668	0.174	0.165	0.195
Control	6 × L2–L3 and 6 × L4–L5	0.917	0.337	0.368	0.951	0.935	0.548	0.376	0.304
AR
Laminectomy	5 × L2–L3 and 6 × L4–L5	0.563	0.987	0.249	0.979	0.928	X	0.161	X
Adjacent	6 × L1–L2 and 6 × L3–L4	0.108	0.826	0.384	0.294	0.189	0.850	0.647	0.396
Control	6 × L2–L3 and 6 × L4–L5	0.416	0.550	0.039	0.387	0.390	0.414	0.179	0.621

Abbreviations: AR, axial rotation; FE, flexion and extension; LB, lateral bending; ROM, range of motion; X, not analyzed.