Retrieval analysis of alumina ceramic-on-ceramic bearing couples

Figures & data

Figure 1. Typical bearings illustrating minimal wear at the cup periphery (1), minimal wear on the femoral head (2), minimal wear at the center of the cup and rim wear peripherally (3), and stripe wear on the femoral head (4).

Table 1. Demographic data on patients and on wear patterns in femoral head and acetabular components

A	B	C	D	E	F	G	H	I
MF	74	OA	1988	2000	12	32	Peripheral and central	Peripheral and central
BW	72	OA	1985	2001	16	32	Peripheral	Peripheral
NM	85	OA	1986	2000	14	38	Central stripe wear	Central and rim wear
DD	83	OA	1983	2001	18	32	Periphery	Peripheral
JF	85	OA	1984	2002	18	32	Central stripe wear	Central and rim wear
DAS	70	OA	1983	2002	19	32	Peripheral	Central
RL	51	SUFE	1982	2002	20	38 (skirted head)	Central stripe wear	Central, NO rim wear
CT	78	OA	1984	2003	19	38	Peripheral	Peripheral
JL	62	DDH	1991	1998	7	32	Central	Central

A Case

B Age

C Primary Diagnosis

 DDH: developmental dysplasia of hip

 OA: osteoarthritis

 SUFE: slipped upper femoral epiphysis;

D Year implanted

E Year of revision surgery

F Time to revision, years

G Head size, mm

H Main area of wear on femoral head ^a

I Main area of wear on cup ^a

^a Central was the inner 50% of the bearing and peripheral was the remainder of the bearing.

Figure 2. Surface topography of femoral head on smooth (top panel), roughened (middle panel), and stripe-worn areas (bottom panel). The graphs have the same scales on the x- and y-axis as the graph at the bottom with stripe wear.

Figure 3. Atomic-force microscope images of smooth areas (1), darkened areas (2), roughened areas (3), and stripe-worn areas (4) of femoral heads, all at 2 magnifications.

Table 2. Surface roughness of femoral heads for smooth and rough areas according to the presence/absence of stripe wear

Wear pattern	Area on head	Srms(SD)/µm	Sa (SD)/µm	Ssk(SD)/µm
Stripe (n = 3)	Rough	0.645 (0.285)	0.402 (0.246)	–4.053 (1.381)
	Smooth	0.010 (0.002)	0.008 (0.002)	–1.881 (1.592)
Minimal (n = 6)	Rough	0.289 (0.057)	0.156 (0.043)	–6.130 (1.36)
	Smooth	0.011 (0.002)	0.008 (0.001)	–4.235 (3.578)

S_a, S_rms, and S_sk are the 3D expressions for surface roughness.

Table 3. Surface roughness of acetabular components for smooth and rough areas

Wear types	Area on cup	Srms (SD)/µm	Sa (SD)/µm	Ssk (SD)/µm
Minimal (n = 9)	Rough	0.151 (0.059)	0.062 (0.020)	–8.79 (5.680)
Smooth	0.014 (0.002)	0.010 (0.002)	–2.89 (2.701)

S_a, S_rms, and S_sk are the 3D expressions for surface roughness.

Table 4. Diametral clearances of bearings that were friction-tested

Bearing	Diameter (µm)			Diametral
	1	2	3	Average	clearance (µm)
Head MF	31.885	31.885	31.879	31.883	463
Cup MF	32.341	32.358	32.338	32.346
Head DD	31.999	32.002	32.000	32.000	116
Cup DD	32.113	32.119	32.117	32.116
Head JF	31.932	31.931	31.930	31.931	171
Cup JF	32.096	32.106	32.103	32.102
Head DAS	31.984	31.978	31.984	31.982	133
Cup DAS	32.116	32.115	32.113	32.115
Head JL	32.006	32.004	32.003	32.004	105
Cup JL	32.108	32.108	32.110	32.109

Figure 4. Stribeck plots of bearings with minimal wear and stripe wear, and of a newly manufactured bearing.