Hip arthroplasty pseudotumors ‘cause for great concern’

By Lynda Williams

Pseudotumors may be 10 times more common in patients after metal-on-metal (MoM) hip resurfacing and total hip replacement (THR) than thought, suggest Dutch researchers.

The study, published in the UK edition of the Journal of Bone and Joint Surgery, reveals a "substantially higher" rate of periarticular soft-tissue mass development in MoM patients than the 1-4% of cases previously identified.

"Because most revision cases were identified only after an intensive screening protocol, we recommend close monitoring of patients with MoM THR," say C Verheyen (Isala Klinieken, JW Zwolle) and co-workers.

The team examined for pseudotumors in 119 patients who underwent MoM THR with large-diameter femoral heads between 2005 and 2007 using ion levels, radiographs, and computed tomography. Patients with pseudotumor symptoms, such as pain, swelling, clicking, or subluxation, were examined using magnetic resonance imaging and ultrasound-guided biopsy.

Pseudotumors were defined as a semi-solid or cystic periprosthetic mass of 2 cm in diameter or larger other than malignancy, scar tissue, or bursa.

An average of 3.6 years after surgery, CT images for 109 hips in 108 patients were available, revealing pseudotumors in 42 (39%) patients. A further four tumors were found in the contralateral hip in patients who had bilateral arthroplasty, two of whom had pseudotumors in both hips.

In multivariate analysis, serum cobalt ion levels above 5 µg/mL were the only significant predictive factor for pseudotumors. Patients with elevated cobalt were four times more likely to develop pseudotumors than those with lower levels, after adjusting for age, gender, surgical characteristics, allergy, and other factors.

Thirteen patients underwent revision surgery, revealing significant bone loss, accompanied by extensive metallosis, periarticular swelling, and necrosis, or a large cystic or semi-solid tumor, the researchers report. These patients were given a polyethylene acetabular component and a smaller diameter metal head.

In addition, ultrasound-guided biopsy samples from 24 patients showed mixed histiocytes, perivascular aggregates, necrosis, and metal debris.

Verheyen et al observe that patients with and without pseudotumors did not significantly differ with regard to clinical scores assessing THR outcome, reflecting the slow and insidious development of the masses.

"When symptoms of swelling, pain in the groin and clicking become sufficient to warrant revision, a sizeable pseudotumour with extensive local-tissue destruction may already be present," they warn.

They therefore conclude that "the high rate of pseudotumour formation and the accompanying local soft-tissue destruction at the time of revision found in our patients is a cause for great concern"

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  1. carol carol United States says:

    They also found a fourfold increased risk of pseudotumors in patients with elevated metal ion levels. The researchers looked at people with a biomet implant, but we can be sure that these findings apply to all metal replacements.

  2. lynne lynne United States says:

    i need info on the biomet implant with the relationship to the pseudotumors. my husband has had 3 thr and he has a plastic liner,but a swelling around the implant that feels hot to the touch and he says is squishey feeling,he was tested for cobalt and chromium ,the results said the levels were within normal limits.he is permantly disabled from this, it continues to worsen.would appreciate any info,thank you

  3. Jim Senka Jim Senka Canada says:

    I have had revision surgery to remove 5% of a pseudo tumour (and also replace the metal on poly parts with metal on ceramic).   a year and a half later the pseudo tumour has returned.  I feel that it was caused by wear of the parts.  My surgeon feels it is because 'my body doesn't like the parts'.  He has since "fired" me as a patient because 'we've lost confidence in each other'.  It seems as if some of these guys don't have time to discuss things with their patients.

  4. Jim Senka Jim Senka Canada says:

    (typo above  should read "85" of the pseudo tumour removed.) At a recent visit to my new surgeon, he doesn't feel that the pseudo tumour has returned, but rather, 2 bursae filled with fluid.  I hope he's right.

  5. Bernhard Ferié Bernhard Ferié Germany says:

    Last year two of these were discovered and I am wondering what to do as the perspectives after 4 major and 2 minor operations point at another revision - with a doubtful outcome - so good luck to us all!

  6. cindy haas cindy haas United States says:

    I am 44 y.o and had bilat mom hips in 2001. R hip was revised after it loosened in 2009. Its now 2015 and I have for 9months a very large 10cm by 4cm mass on back of my thighlocated right under the buttocks. Very swollen and painful with a rash lesion on it.  Scans say a multicompartment (3) filled with a thicker fluid. Fluid was removed and lab says no bacteria but over 14,000 WBC. I have no pain in L groin but dr's think it could be metolosis for MRI says it tunnels to L hip. Now they want to rule out cancer. Looking for someone with simular type mass.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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