Catastrophic failure of 4 cobalt-alloy Omnifit hip arthroplasty femoral components

Figures & data

Summary and profile of each case

Case	Weight (kg)	BMI (kg/m^2)	Age^a	Years in situ	Complications	Revision surgery prior to stem fracture	Skirted head
1	80	26	57	17	recurrent dislocations	yes, once	no
2	82	24	64	14	recurrent dislocations and early infection	yes, 3 times	yes
3	129	39	76	12	none	no	yes
4	120	47	71	10	none	no	yes

^aat primary surgery

Figure 1. Macrophotograph of fractured stem. Insert shows surface of fracture.

Figure 2. Intergranular cracking on the superior tensile surface of the trunnion. Note the large grains.

Figure 3. Extensive carbide precipitation at the grain boundary.

Figure 4. Macrostructure of a cross section taken through the neck of a fractured stem. Note the large grains and the presence of precipitates at the grain boundaries.