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Improving Results of Total Hip Replacement in the Under-50 Crowd

Doctors are reluctant to replace hip and knee joints in patients under 50 years old. There are good reasons for this, but changes are on the way.

The biggest concern with early joint replacement is failure of the implant. Younger patients tend to be more active and wear the joint out sooner. Implants don't last as long, and another implant is needed to replace the first worn-out one. With each operation there's the risk of bone loss and loosening of the implant. Knowing which implant to use is also a challenge. There just aren't enough studies yet to guide doctors in choosing the type of implant that will last the longest for each patient.

In this study, 561 total hip replacements (THRs) were done on patients younger than 50. Within that group was a subset of patients who were 40 years old or younger. Different kinds of implants were used and compared. The authors report results after five, 10, and 15 years.

In general, implant parts coated with a full (rather than partial) porous covering held up the best. When cement isn't used to hold the implant in place, a press-fit type of implant is used. The press-fit socket (the cup portion) of the implant wore out before the press-fit ball of the joint.

The authors report that the weak link in this study was the polyethylene (PE) liner inside the cup. The rest of the implant held up well even after 15 years. The PE liners wear out in 10 to 15 years and have to be replaced. A thicker PE may be needed. Studies of other types of materials, such as ceramic and metal, are needed to make this decision.

If survivor rates of the PE aren't included, then 90 percent of the THRs lasted 10 years. After 15 years, 80 percent were still working well. It's likely that more patients will be given the green light for early hip replacement in years ahead. Finding THR materials that won't wear out is the key.

References: James P. McAuley, MD, et al. Total Hip Arthroplasty in Patients 50 Years and Younger. In Clinical Orthopaedics & Related Research. January 2004. Vol. 418. Pp. 119-125.

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