The technology of hip replacement

Even before I was resigned to having a hip replacement done, I was already reading up on them.  I had heard that they only last a certain amount of time before they wear out.  Apparently those estimates were on the low side- the original ones lasted about double what they thought.  And with the newer technology, I was told that mine will last upwards of 25 years, even with my high level of activity.

The prosthetic I'll be getting is this one: a J&J (DePuy) Pinnacle.

The issues in the past with hip replacements is that they used a small ball which limited the range of motion.  It also had a smaller surface area- yet the same amount of force, which causes higher wear.

Newer designs use a large ball, trying to approximate the original femur.  The Pinnacle design isn't the largest one, though it is pretty big.  The Pinnacle socket is a two-piece. There's a titanium cup which is put in the pelvis, and a liner.   That's the selling point of the pinnacle- the liner (and ball) can be swapped out.  The have balls in metal and ceramic, and liners in plastic, ceramic and metal, giving the surgeon a lot of choice.  Ceramic has fallen out of favor because some squeak after time.  Plastics are popular, but they don't wear as long as metal.   Metal has concerns because metal on metal causes ions of the metal to be released with some uncertainty as to what happens over time.   This new joint is design to have much lower wear because it allows the synovial fluid to lubricate the joint as if it would a normal joint.

The other half of the joint is a stem which goes into the femur and the ball on the end.  As I mentioned earlier, the ball is a relatively large diameter at 36mm or so (compared to the early balls which were 24mm), but not as large as the original femur which is around 54mm.  I did some searching on studies, which found that head sizes >32mm had a huge improvement in range-of-motion and lessened the chance of dislocation.

So, I'm satisfied with the choice of component.  And its modular design will allow the liner to be changed (I assume) at some point if the materials wear or there's a problem.