Have you ever heard of getting arthritis in a joint replacement? That’s what my doctor tells me is causing my hip pain. How is that possible?

Prosthetic arthritis is a very real condition. It is caused by erosion or damage to the joint cartilage. This type of problem occurs with a joint implant called a unipolar hemiarthroplasty.

The unipolar implant is one of the first type of partial hip replacements designed. It replaces the round head of the femur (thigh bone). It has a stem attached to it that goes down inside the shaft of the femur to hold it in place.

Younger, more active patients are more likely to develop this kind of problem. The implant moving inside the hip socket chips away small pieces of bone and cartilage leading to cartilage erosion also known as prosthetic arthritis.

A newer type of implant was made to try and avoid this problem. It’s called the bipolar prosthesis. Besides the femoral implant, a plastic-lined, metal cup is inserted into the patient’s own natural acetabulum (hip socket). Instead of just the femoral head moving in the acetabulum (unipolar implant), the bipolar allows for two points of motion. The femoral head moves and rotates inside the cup and the cup moves and rotates inside the acetabulum.

The bipolar hemiarthroplasty is more expensive but recommended for active patients younger than 65.