Balancing Rigidity and Safety of Pedicle Screw Fixation via a Novel Expansion Mechanism in a Severely Osteoporotic Model

Table 1

Mean and standard deviation for all mechanical parameters recorded.

	Trabecular block				Trabecular block (with PMMA augmentation)				Composite block
	Pullout (N)	Stiffness; (N/mm)	Energy to failure; (N*mm)	Energy to removal; (N*mm)	Pullout (N)	Stiffness; (N/mm)	Energy to failure; (N*mm)	Energy to removal; (N*mm)	Pullout (N)	Stiffness; (N/mm)	Energy to failure; (N*mm)	Energy to removal; (N*mm)
Standard
Mean	339	171	425	1300	338	161	499	2570	303	177	318	942
Standard deviation	9	7	21	21	69	12	208	229	10	25	61	133
Expandable
Mean	321	160	396	1650	360	164	529	3200	293	179	336	1380
Standard deviation	10	11	33	68	28	6	86	527	31	21	94	199