Pseudotumours associated with metal-on-metal hip resurfacings

Abstract

We report 17 patients (20 hips) in whom metal-on-metal resurfacing had been performed and who presented with various symptoms and a soft-tissue mass which we termed a pseudotumour. Each patient underwent plain radiography and in some, CT, MRI and ultrasonography were also performed. In addition, histological examination of available samples was undertaken. All the patients were women and their presentation was variable. The most common symptom was discomfort in the region of the hip. Other symptoms included spontaneous dislocation, nerve palsy, a noticeable mass or a rash. The common histological features were extensive necrosis and lymphocytic infiltration. To date, 13 of the 20 hips have required revision to a conventional hip replacement. Two are awaiting revision. We estimate that approximately 1% of patients who have a metal-on-metal resurfacing develop a pseudotumour within five years. The cause is unknown and is probably multifactorial. There may be a toxic reaction to an excess of particulate metal wear debris or a hypersensitivity reaction to a normal amount of metal debris. We are concerned that with time the incidence of these pseudotumours may increase. Further investigation is required to define their cause.

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

“…Periprosthetic soft tissue lesions around MOM hip implants have been reported by numerous authors using various terms including ALTR, ARMD, ALVAL, metallosis, and pseudotumor [1,17,23,24,33]. These soft tissue masses can be associated with major tissue destruction [24] and therefore early recognition and prompt revision are critical.…”

“…These soft tissue masses can be associated with major tissue destruction [24] and therefore early recognition and prompt revision are critical. Our aims were to identify which MRI characteristics correlated with the ALVAL score and intraoperative tissue damage and to develop a predictive model using modified MRI to detect ALVAL as confirmed by histology and to quantify intraoperative tissue damage.…”

“…However, reports have emerged describing the presence of periprosthetic soft tissue lesions, which have been described interchangeably as adverse local tissue reactions (ALTR) [1], adverse reactions to metal debris (ARMD) [17], aseptic lymphocytic vasculitis-associated lesions (ALVAL) [33], metallosis [23], and pseudotumors [24]. Although these soft tissue masses are not malignant or infectious, they can be associated with catastrophic local tissue destruction [24] and complication rates of 50% after revision arthroplasty [6]. The importance of early detection and prompt revision therefore is paramount.…”

Magnetic resonance imaging of the postoperative hip

“…ALVAL has been described in the setting of MOM total hip arthroplasty and MOM hip resurfacing arthroplasty (51)(52)(53) and may manifest as synovitis, bursitis, periprosthetic osteolysis, and cystic or solid masses, which have previously been termed ''pseudotumors'' (53,54).…”

“…The exact prevalence of hypersensitivity reactions following MOM arthroplasties is unknown but in larger retrospective studies ''pseudotumors'' have been reported in up to 1% of patients with MOM hip resurfacing arthroplasty at revision surgery (52,53). The incidence may in fact be higher than this on imaging, as ''pseudotumors'' can occur in asymptomatic patients (53)(54)(55).…”