Roles of the screw types, proximity and anterior band wiring in the surgical fixation of transverse patellar fractures: a finite element investigation

Table 2 Maximum displacement of the fragment, gap opening, contact pressure and contact area of the fractured patella with screw and wire under various loading magnitudes and directions

	Without wire under 400-N			With wire under 400-N			With wire under 800-N
	Partial thread	Headless compression	Full thread	Partial thread	Headless compression	Full thread	Partial thread	Headless compression	Full thread
Loading direction 45°
5 mm screw placement Max. fragment displacement (mm)	1.08	0.85	0.79	1	0.84	0.79	1.97	1.54	1.49
Max. gap opening (mm)	0.65	0.43	0.36	0.57	0.4	0.36	1.11	0.7	0.63
Max. contact pressure (MPa)	3.24	2.79	2.54	2.63	2.45	2.32	5.6	5	4.9
Contact area (mm²)	192	259	307	205	273	320	180	259	308
10 mm screw placement Max. fragment displacement (mm)	3.1	2.79	2.06	1.24	1.23	1.2	2.19	2.16	2.08
Max. gap opening (mm)	2.71	2.34	1.59	0.81	0.8	0.76	1.36	1.32	1.23
Max. contact pressure (MPa)	9.18	8.85	7.21	3.6	3.5	3.5	6.7	6.5	6.4
Contact area (mm²)	94	112	163	129	142	175	135	144	174
Load direction parallel
5 mm screw placement Max. fragment displacement (mm)	0.45	0.35	0.33	0.45	0.35	0.33	0.86	0.63	0.59
Max. gap opening (mm)	0.35	0.22	0.19	0.35	0.22	0.19	0.67	0.38	0.32
Max. contact pressure (MPa)	0	0.23	0.19	0	0.19	0.17	0	0.39	0.37
Contact area (mm²)	0	92	120	0	103	110	0	86	121
10 mm screw placement Max. fragment displacement (mm)	1.46	1.24	0.88	0.75	0.75	0.71	1.12	1.1	1.07
Max. gap opening (mm)	1.35	1.1	0.73	0.63	0.61	0.56	0.86	0.82	0.77
Max. contact pressure (MPa)	2.81	2.8	2.17	0.86	1.3	1.47	1.21	1.67	2.15
Contact area (mm²)	63	91	148	44	81	144	33	67	137

ISSN: 1471-2474