Heterotopic ossification after the use of recombinant human bone morphogenetic protein-7

Table 1 Analysis of the parameters affecting the development of heterotopic ossification

Parameter		No. of patients	HO	HO rate (%)	P value (χ2)	P value (logistic regression firth’s correction)
Gender	Male	60	15	25
	Female	24	0	0.0	0.007	0.081
	≤ 30	20	6	30.0
Age	31-55	39	8	20.5	0.067	0.205
	≥ 56	25	1	4.0
Extremity	Upper	13	1	7.7
	Lower	71	14	19.7	0.298	0.733
Defect size	Critical	42	8	19.0
	Non critical	42	7	16.0	0.776	0.997
Chronicity	> 1 yr	33	4	12.1
	< 1 yr	51	11	20.3	0.229	0.731
Infection	Yes	30	4	13.3
	No	54	11	20.3	0.420	0.451
Soft tissue defects	Yes	9	3	33.3
	No	75	12	16.0	0.200	0.287
Previous procedures	1	56	8	14.3
	2-3	28	7	25.0	0.227	0.315
Graft type	Autograft	67	13	19.4
	Allograft	9	0	0	0.463	0.663
	No graft	8	2	25.0
Amount of rhBMP-7	1 vial	75	14	18.6
	2 vials	9	1	11.1	0.576	0.629

P values with the use of χ² test and with the use of logistic regression model under Firth’s correction. HO: Heterotopic ossification; rhBMP-7: Recombinant human bone morphogenetic protein-7.