Table 1. Patient characteristics of Groups I and II after matching.

			Group I	Group II
Number of hips			33	33
	Sex	Male	2	2
		Female	31	31
Mean age (years)			35.1 (22.6–53.5)	35.7 (20.5–57.1)
	Side	Right	10	17
		Left	23	16
Preoperative type
	A		1	1
	B		2	2
	C1		16	16
	C2		14	14
Preoperative stage
	1		15	15
	2		13	13
	3 (3A+3B)		5	5
Mean follow–up period (years)			5.9 (2.0–14.5)	8.7 (2.1–24.8)*

*P<0.05, unpaired t-test.