Selection of internal fixation method for femoral intertrochanteric fractures using a finite element method

Table 1 Material properties of the femur and internal fixation model[28,29]

Material	Elastic modulus (Mpa)	Poisson ratio
Cortical bone	16800	0.29
Cancellous bone	260	0.2
Internal fixation	110000	0.3

Table 2 Grouping according to different models

	Normal standing A			Slow walking B			Fast walking C			Stair descent D
	Medial defect a	Lateral defect b	Lateral and medial defect c	Medial defect a	Lateral defect b	Lateral and medial defect c	Medial defect a	Lateral defect b	Lateral and medial defect c	Medial defect a	Lateral defect b	Lateral and medial defect c
PFNA 1	1Aa	1Ab	1Ac	1Ba	1Bb	1Bc	1Ca	1Cb	1Cc	1Da	1Db	1Dc
ITN 2	2Aa	2Ab	2Ac	2Ba	2Bb	2Bc	2Ca	2Cb	2Cc	2Da	2Db	2Dc
PFNA + steel wire 3	3Aa	3Ab	3Ac	3Ba	3Bb	3Bc	3Ca	3Cb	3Cc	3Da	3Db	3Dc
PFNA + plate 4		4Ab	4Ac		4Bb	4Bc		4Cb	4Cc		4Db	4Dc
PFNA + steelwire + plate 5		5Ab	5Ac		5Bb	5Bc		5Cb	5Cc		5Db	5Dc

PFNA: Proximal femoral anti-rotation intramedullary nail; ITN: Integrated dual-screw fixation.

Table 3 Comparison of the maximum stress and maximum displacement among different fixation methods, different stress modes, and different fracture types

	Normal standing A			Slow walking B			Fast walking C			Stair descent D
	a	b	c	a	b	c	a	b	c	a	b	c
Maximum stress at the main nail (MPa)
1	176	92	239	334	183	456	404	235	556	473	288	653
2	203	102	229	402	204	445	496	256	546	588	307	641
3	121	84.8	141	318	173	392	383	219	438	425	265	515
4		89	213		178	416		228	515		278	608
5		67	107		134	205		167	253		203	309
Maximum displacement of proximal femur (mm)
1	1.22	0.85	1.35	2.39	1.70	2.61	2.95	2.12	3.23	3.51	2.55	3.84
2	0.95	0.69	1.19	1.89	1.39	2.33	2.35	1.74	2.89	2.80	2.10	3.44
3	0.85	0.70	0.93	1.64	1.40	1.82	2.04	1.75	2.29	2.44	2.09	2.79
4		0.84	1.31		1.66	2.52		2.08	3.12		2.49	3.72
5		0.75	0.82		1.49	1.62		1.87	2.02		2.24	2.42

a: Medial defect; b: Lateral defect; c: Lateral and medial defect; 1: PFNA; 2: ITN; 3: PFNA + wire 3; 4: PFNA + plate; 5: PFNA + wire + plate; PFNA: Proximal femoral anti-rotation intramedullary nail; ITN: Integrated dual-screw fixation.