Pseudotumors Are Common in Well-positioned Low-wearing Metal-on-Metal Hips

Abstract

Background Pseudotumors are sterile inflammatory lesions found in the soft tissues surrounding metal-on-metal (MOM) and metal-on-polyethylene hip arthroplasties. In patients with MOM hip arthroplasties, pseudotumors are thought to represent an adverse reaction to metal wear debris. However, the pathogenesis of these lesions remains unclear. Currently, there is inconsistent evidence regarding the influence of adverse cup position and increased wear in the formation of pseudotumors. Questions/purposes We therefore determined whether pseudotumor formation was associated with (1) adverse cup position, (2) raised metal ion levels, and (3) increased wear rates of the retrieved components. Methods We retrospectively reviewed all 352 patients for whom we had retrieved specimens from revisions of a current-generation MOM hip prosthesis between February 2008 and September 2010; of these, 105 met our inclusion criteria. We used multivariate logistic regression analysis to compare acetabular orientation, metal ion levels before revision, and component wear rates between patients with (n = 72) and without (n = 33) pseudotumors, according to findings on metal artifact reduction sequence MRI. Results The proportion of patients demonstrating evidence of a pseudotumor in well-positioned hips was similar to those with adverse cup positions (67% and 66%, respectively). Patients revised with pseudotumors had similar whole-blood metal ion levels and component wear rates to those who were not revised. Conclusions Pseudotumors were not associated with increased wear or metal ion levels, suggesting patient susceptibility is likely to be more important.

Frequent Femoral Neck Osteolysis With Birmingham Mid-head Resection Resurfacing Arthroplasty in Young Patients

“…Cobalt, chromium, and titanium have been shown to affect bone turnover in animal studies by decreasing bone formation and inducing resorption [20,24], and all three metal ions can be released from the BMHR device. However, all patients with osteolysis in our series had normal blood metal ion levels; and pseudotumors have been found common in well-functioning low-wearing MoM hips with no osteolysis [22,33]. In addition, in ARMD, one would expect the osteolysis to affect both the acetabular and the femoral neck bone, a finding noted in previous papers on osteolysis associated with MoM hips [10,28].…”

“…Patients' median OHS (using the 48-point OHS) improved from 26 (range, [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] preoperatively to 46 (range, [35][36][37][38][39][40][41][42][43][44][45][46][47][48], and UCLA score improved from 5 (range, 2-8) to 8 (range, 4-10) at latest review (paired t-test p \ 0.001 for both). There was no difference in median [35][36][37][38][39][40][41][42][43][44][45][46][47][48] or in the median postoperative UCLA scores between males (8; range, 5-10) and females (8; range, 4-10) (Mann-Whitney U p = 0.293 and p = 0.115, respectively).…”

MRI Predicts ALVAL and Tissue Damage in Metal-on-Metal Hip Arthroplasty

“…Twenty-one (30%) of the primary hip arthroplasties were performed at our institution and the remainder were performed in other centers. The reasons for revision were determined according to the categories used by the National Joint Registry for England and Wales [7,19]. These included aseptic acetabular loosening (n = 8), aseptic femoral loosening (n = 3), component malalignment (n = 4), infection (n = 1), and unexplained pain (n = 54).…”

The John Charnley Award: Diagnostic Accuracy of MRI Versus Ultrasound for Detecting Pseudotumors in Asymptomatic Metal-on-Metal THA

“…Numerous reports have highlighted the problem of pseudotumors in patients who have undergone large-head MOM THA [3,4,11,15,22,26,28]. The prevalence of pseudotumors is higher with this type of THA than with hip resurfacing, and MOM implants have been the subject of recalls and warnings from various regulatory agencies.…”