Hip resurfacing has become very popular of late for younger, more active patients with hip arthritis as it’s slightly less invasive than a total hip replacement. In this hip replacement surgery (yes, it’s still a hip replacement surgery), the ball and socket bones are ground down and then a new ball and cup are placed rather than getting rid of most of the bone. Because the implant size is smaller, these hip prostheses need to be the stronger metal on metal variety.
While it’s claimed that hip resurfacing has a lower wear rate, this may not be the case. In addition, other problems may be “surfacing” about resurfacing. Last week the FDA warned that the metal on metal implants used for hip resurfacing leach metal particles which have been associated with many health problems. In addition, other studies have shown femoral neck fracture is a complication of hip resurfacing as the femoral neck is weakened by the surgery to implant the device.
Piling on the concerns were several different presentations at the American Academy of Orthopedic Surgeons conference that looked into metal on metal hip resurfacing. Rather than finding that the devices lasted longer, they found that within 4 years, about 4% of these less invasive surgeries had to be converted into a more invasive total hip replacement surgery because the implant failed. This hip resurfacing failure rate was almost double in women (approximately 8%). In addition, a different British study found that the abnormal wear of these devices wasn’t any better in hip resurfacing when compared to a total hip replacement. In other studies the patient reaction to the metal was the problem. For example, local tissue reactions were common even when there was no history of prior metal sensitivity.
In addition, there’s growing concern that the patient’s metal sensitivity response to the prosthesis may be tied to the failure of the resurfacing surgery. In a way, the prosthesis may be rejected by the body and the metal “attacked” which may cause more more wear of the implant. This same serious prostheses rejection problem also leads to local tissue reactions like pseudotumors. These “False tumors” (really just angry tissues) develop in about 1% of female patients. When these tumors do occur, they can place pressure on the main nerve of the leg (femoral nerve). In addition, one recent study showed that metal on metal hip prostheses were associated with more post-operative groin pain. This study concluded, “The rate of groin pain was 7% (15 of 217 patients) after THA with conventional bearing surfaces, 15% (4 of 26 patients) with metal-on-metal THA and 18% (7 of 39 patients) with total hip resurfacing.” Younger patients were more likely to report groin pain postoperatively and more likely to have metal-on-metal bearing surfaces.This is really concerning, as this pressure can lead to weakness and numbness in the leg.
The upshot, while hip resurfacing is little less invasive, it seems to have many problems “surfacing”.