Intended for healthcare professionals

CCBYNC Open access
Research

Comparative assessment of implantable hip devices with different bearing surfaces: systematic appraisal of evidence

BMJ 2011; 343 doi: https://doi.org/10.1136/bmj.d7434 (Published 29 November 2011) Cite this as: BMJ 2011;343:d7434

Re: Comparative assessment of implantable hip devices with different bearing surfaces: systematic appraisal of evidence

My clinic’s experience with metal-metal hips is emblematic of the difficulties surgeons have in evaluating the risks and benefits of new arthroprosthetic technology. We assume that a regulatory pre-market approval process and a post market monitoring process insure the efficacy and safety of newer devices.

Our initial metal-metal hip experience was favorable. We falsely attributed this success to the metal-metal bearing. Several years into our experience an uncharacteristically high percentage of our patients had progressive unresolved or new hip pain. Some of these patients had gross metal debris about the hip with tissue damage. Two of these patients had remarkably high cobalt levels, cognitive decline, cranial neuropathy and early cardiomyopathy. These cases of “Arthroprosthetic Cobaltism” were published.(Tower 2010)

We have just identified our fourth case of arthroprosthetic cobaltism. A pre-revision serum cobalt of > 200 mcg/L (normal is < 1) was found by the patients primary provider during a work up for progressive central nervous system, cardiac and constitutional symptoms. An elevated TSH was also found. The patient’s metal-metal hip had been in for about two years and over one year hip pain and noise were noted.

Patients with metal-metal hips may present to their primary provider with combinations of symptoms related to the prosthetic hip, nervous system, heart, and thyroid gland.

Tower, S. S. (2010). "Arthroprosthetic cobaltism: neurological and cardiac manifestations in two patients with metal-on-metal arthroplasty: a case report." The Journal of bone and joint surgery. American volume 92(17): 2847-2851.

stephentower@mac.com

Competing interests: No competing interests

02 December 2011
Stephen, S Tower
Orthopedic Surgeon
Anchorage Fracture and Orthopedic Clinic
3831 Piper Street, Suite 220, Anchorage, Alaska 99508