Table 2.

Causes of multifocal and oligofocal osteonecrosis (ON) in patients with ON

Cause of ON	Multifocal ON (n = 26)	Oligofocal ON (n = 228)	Any ON (N = 254)	p-value
Idiopathic	4 (15.4)	60 (26.3)	64 (25.2)	0.001
Trauma	1 (3.8)	24 (10.5)	25 (9.8)
Comorbidity requiring corticosteroids and immunosuppressive agents	18 (69.2)	70 (30.7)	88 (34.6)
Excessive alcohol intake	3 (11.5)	74 (32.5)	77 (30.3)

ON osteonecrosis. Pearson’s chi square test was used to compare causes of multifocal and oligofocal ON