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Uncemented Total Hip Joints Revised with Cement

A new hip joint can be put in with or without cement. In either case the implant can come loose. If so, the patient may need another operation to revise the hip. Doctors keep track of how often implants fail and what caused the failure. But they don't stop there. They also pay attention to what happens to the revised hip. This study looks at the long-term results of failed uncemented hips revised with the use of cement.

When an uncemented implant fails, doctors and patients may prefer a cemented revision. Cement holds right away, giving the patient quick pain relief. Using cement may also give the patient with a failed uncemented implant some peace of mind.

Even with a cemented revision, however, doctors found a high rate of failure after the revision. The failure rate was greater than when cement was used in the first place. In fact almost a third of the uncemented implants revised with cement came loose again.

The researchers think this poor result happens for several reasons. It's sometimes hard to get the cement to ooze into the tiny pores of the bone. This means that the cement fails to make a good connection with the bone. Without this bond the strength of the cement to bone is much lower. There's also a lot of bone loss that occurs during loosening. And there's even more bone that is lost during the revision operation. Using a longer stem in the thigh side of the implant has fewer failures. Older patients (greater than 70 years) seem to fare better.

The authors conclude that, in general, revising a hip replacement is best done with cement. The doctor needs to factor in other considerations, such as age, activity level, medical status, and pattern of bone loss already present. Uncemented implants are a good option when little bone remains inside the thighbone.

References: Charles M. Davis, III, MD, PhD, et al. Cemented Revision of Failed Uncemented Femoral Components of Total Hip Arthroplasty. In The Journal of Bone and Joint Surgery. July 2003. Vol. 85-A. No. 7. Pp. 1264-1269.

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