Subsidence of titanium straight stems in combination with highly viscous bone cement

Abstract

Varying results and a high rate of subsidence have been reported for the straight femoral stem (M.E. Muller) made of titanium alloy. We examined subsidence in 135 titanium-alloy straight stems implanted with high viscosity cement after 68.8+/-11.5 months using a digital high-precision method (EBRA-FCA). One revised implant showed a subsidence of 14.6 mm and another 2.5 mm over 5 years. A third implant without migration was found to be loose. The 122 implants without loosening showed a mean subsidence of 0.1+/-0.1 mm, and focal osteolysis was seen in two. Altogether, we found subsidence of the titanium stems very small. The small subsidence may be related to the use of high viscosity bone cement.

Fig. 1

Migration diagram and X-rays of a patient with Müller straight stem left with primary osteoarthritis. The observation time is shown on the abscissa. A large graduation mark corresponds to 1 year; a small one corresponds to 1 month. The ordinate shows stem subsidence in millimetres: A large graduation mark corresponds to a millimetre, a small one corresponds to half a millimetre. On the left, an X-ray from 1992; on the right from 1997. The migration diagram shows that for the whole observation period of 60 months, the stem implant shows a migration of 14.6 mm. The implant was revised.

Fig. 2

Migration diagram and X-rays of a patient with a straight stem prosthesis with primary osteoarthritis. At the bottom left, an X-ray from 1992; bottom right, one from 1996. The migration diagram shows that during the observation period of 54 months, no subsidence was detected outside the measuring range of 1.5 mm despite the finding of osteolysis. Intra-operatively, stem loosening was detected.

Fig. 3

Migration diagram and X-rays of a patient with a cemented titanium Müller straight stem with primary osteoarthritis. On the left, an X-ray from 1991; on the right, one from 1996. The migration diagram shows that during the observation period of 72 months, no migration was found outside the measuring range of 1.5 mm despite the finding of focal osteolysis. As a result of the lack of clinical symptoms, the patient was recommended to have frequent clinical and radiological checkups.