ORLANDO, Fla. – Elevated metal ion levels, loose cups either radiographically or clinically and psychological changes are among the indications orthopedic surgeons need to consider for the revision of metal-on-metal hip articulations, according to a presenter at the Current Concepts in Joint Replacement Winter Meeting.
“You do not have to worry much about the patient who has ions below 10 [parts per billion], no clinical symptoms and a good X-ray,” Lawrence D. Dorr, MD, said during his presentation. “If you have an X-ray that has evidence of radiolucent lines around the entire cup, then you have a patient who you have to worry about — with or without symptoms. They could get progressive loosening. You need to follow them at a 6-month interval.”
Dorr said elevated metal ion levels, especially cobalt, mean increased wear so local osteolysis and bone destruction are risk factors with increased follow-up. For patients with metal ion levels greater than 10 parts per billion and clinical symptoms, he said surgeons need to decide whether to revise the patient’s metal-on-metal (MoM) hip.
Lawrence D. Dorr
“If you do not have the situation where they have frank clinical symptoms and they have high ions on their tests, but you have a patient with psychological changes or you have patients with symptoms of cobalt poisoning, then that is also an indication for revision,” Dorr said.
For patients younger than 75 years with metal ions levels at 25 parts per billion or greater, he recommended surgeons talk with the patients to decide whether to revise. For patients older than 75 years, he said he will wait to see if they develop any symptoms of metal problems or cobalt poisoning.
Patients with clinical symptoms, such as persistent start-up troubles or unrelenting pain with any activity, have loosening and are among those indicated for revision. In addition, soft tissue masses in the groin or anterior hip are other indications for revision of MoM articulations. Cognitive changes, such as memory loss and psychomotor retardation, also indicate revision. Dorr advised surgeons to question patients about shortness of breath as cobalt poisoning will cause cardiac symptoms. – by Kristine Houck, MA, ELS
Dorr LD. Paper #41. Presented at: Current Concepts in Joint Replacement Winter Meeting; Dec. 10-13, 2014; Orlando, Fla.
Disclosure: Dorr receives funding for consulting from DonJoy Global and funding for hotel rooms from Total Joint Orthopedics.