Higher failure rate and stem migration of an uncemented femoral component in patients with femoral head osteonecrosis than in patients with osteoarthrosis

Figures & data

Table 1. Demographic data and results of patients with osteonecrosis and arthrosis of the hip

	Osteonecrosis	Arthrosis	P-value
No. of patients	31	49
Age (years)	51 (29−75)	63 (34−71)	<0.001
Follow-up (years)	6.1 (2−11)	5.9 (4−8)	0.5
Weight (kg)	76 (52−94)	68 (46−98)	0.04
Stem migration (mm)	1.5 (−8.8−0)	0.6 (−2.6−0)	<0.001
Harris hip score (points)	85 (38−100)	92 (80−100)	0.01

Figure 1. The uncemented total hip replacement device with a straight, collarless stem made of a titanium-alu-minium-vanadium alloy (Ti-6Al-4Va), with an additional coating of hydroxyapatite in the proximal two-thirds, which was combined with spherical press-fit cup (Ti-6Al-4Va), a polyethylene liner and a ceramic head.

Table 2. Radiographical evaluation including femoral bone radiolucency, atrophy, hypertrophy and osteolysis in the seven Gruen zones

	Region
	1	2	3	4	5	6	7
Osteonecrosis group (n = 29)
Radiolucency	29	20	5	25	11	7	18
Atrophy	27	23	0	0	0	8	23
Hypertrophy	0	0	13	8	14	0	3
Osteolysis	5	2	0	0	0	0	3
Arthrosis group (n = 47)
Radiolucency	40	13	3	20	6	3	13
Atrophy	40	21	0	0	0	4	10
Hypertrophy	0	0	15	17	19	0	4
Osteolysis	5	0	0	0	0	0	1

Table 3. Radiographical evaluation of the acetabular component including radiolucency, atrophy, and osteolysis in the DeLee and Charnley zones

	Region
	1	2	3
Osteonecrosis group (n = 29)
Radiolucency	12	4	7
Atrophy	2	2	2
Osteolysis	1	1	1
Arthrosis group (n = 47)
Radiolucency	11	4	3
Atrophy	0	2	2
Osteolysis	0	1	0

Figure 2. Kaplan-Meier life-table analysis with stem revision (for any reason) as the endpoint. Bold line: survival curve. Thin lines: 95% confidence limits. In the osteonecrosis group, the survival rate of the femoral component was 74% (95% CI: 55–34). The median follow-up time for the patients was 6.1 (2–11) years.

Figure 3. Kaplan-Meier life-table analysis with mechanical failure as the endpoint. Bold line: survival curve. Thin lines: 95% confidence limits. In the osteonecrosis group, the survival rate of the femoral component was 54% (CI: 31–76). The median follow-up time for the patients was 6.1 (2–11) years.

Figure 4. Kaplan-Meier life-table analysis with stem revision for any cause as the endpoint. Bold line: survival curve. Thin lines: 95% confidence limits. In the osteoarthrosis group, the survival rate of the femoral component was 98% (CI: 94–100). The median follow-up time for the patients was 5.9 (4–8) years.