Similar incidence of periprosthetic fluid collections after ceramic-on-polyethylene total hip arthroplasties and metal-on-metal resurfacing arthroplasties

Abstract

Patients from a randomised trial on resurfacing hip arthroplasty (RHA) (n = 36, 19 males; median age 57 years, 24 to 65) comparing a conventional 28 mm metal-on-metal total hip arthroplasty (MoM THA) (n = 28, 17 males; median age 59 years, 37 to 65) and a matched control group of asymptomatic patients with a 32 mm ceramic-on-polyethylene (CoP) THA (n = 33, 18 males; median age 63 years, 38 to 71) were cross-sectionally screened with metal artefact reducing sequence-MRI (MARS-MRI) for pseudotumour formation at a median of 55 months (23 to 72) post-operatively. MRIs were scored by consensus according to three different classification systems for pseudotumour formation. Clinical scores were available for all patients and metal ion levels for MoM bearing patients. Periprosthetic lesions with a median volume of 16 mL (1.5 to 35.9) were diagnosed in six patients in the RHA group (17%), one in the MoM THA group (4%) and six in the CoP group (18%). The classification systems revealed no clear differences between the groups. Solid lesions (n = 3) were exclusively encountered in the RHA group. Two patients in the RHA group and one in the MoM THA group underwent a revision for pseudotumour formation. There was no statistically significant relationship between clinical scoring, metal ion levels and periprosthetic lesions in any of the groups. Periprosthetic fluid collections are seen on MARS-MRI after conventional CoP THA and RHA and may reflect a soft-tissue collection or effusion. Currently available MRI classification systems seem to score these collections as pseudotumours, causing an-overestimatation of the incidence of pseudotumours.

Prevalence of and Risk Factors for Hip Resurfacing Revision

“…These additional cases might eventually increase our reported prevalence and rates of revision, but the natural history of asymptomatic pseudotumors remains uncertain 46 . It is not clear whether all such lesions eventually require revision 46 , as the frequency of asymptomatic pseudotumors is similar between patients with MoM implants and those with non-MoM implants 47 . An additional limitation is that, although our survival analysis was robust, there is a potential for residual confounding.…”

Advances in MRI around metal

“…With metal‐on‐metal total hip arthroplasty (THA) and the associated major risk of adverse local tissue reactions (ALTR), MARS gained importance . But also with other types of orthopedic implants the so‐called “pseudotumors,” initiated by excessive wear, may be observed . Periprosthetic infection, fluid collections, and abscesses or osteomyelitis are further severe complications that require prompt treatment.…”

Pseudotumor in metal-on-metal hip arthroplasty: a comparison study of three grading systems with MRI

“…Recent studies show that the incidence of pseudotumors is comparable with other THA systems such as cobalt on polyethylene and metal on polyethylene [4, 5]. MoM THA-induced pseudotumors can cause compression of the neurovascular bundle [6, 7].…”

“…Importantly, other radiological studies on pseudotumors do not report a kappa value and therefore the results should be interpreted with caution [3, 19–21]. The reproducibility of these grading systems is of clinical importance and may help to unravel the etiology of a pseudotumor.…”