Metallosis following hip arthroplasty: two case reports

Abstract

Background: There has been increasing recognition of local and systemic adverse events associated with the release of metal ions and nanoparticles from hip arthroplasty components. Adverse local tissue reactions to metal ion debris can include periprosthetic solid and cystic masses known as pseudotumors. These masses can result in pain, swelling, extensive destruction to surrounding hip soft-tissues, and compression syndromes on neurovascular, gastrointestinal, and genitourinary structures. As reports of pseudotumors requiring multidisciplinary excision are limited, we present two pseudotumor cases that were excised through a combined approach.

Case presentations: The first case involves a 60-year-old Caucasian female with a large pseudotumor with intrapelvic and vascular involvement associated with a metal-on-polyethylene total hip arthroplasty, excised with contributions from general surgery, vascular surgery, and orthopedic surgery. Pseudotumor excision was followed by a revision total hip reconstruction in addition to an abductor mechanism reconstruction with tendo-Achilles allograft. The second case is that of a 64-year-old Caucasian female with a pseudotumor in close relationship to the femoral vessels following a metal-on-metal hip resurfacing, excised with a combination of vascular surgery and orthopedic surgery, with subsequent revision total hip reconstruction.

Conclusions: There remains a lack of literature to support the extensiveness of pseudotumor excision required in complex cases with significant intrapelvic or vascular involvement. Given the potential for significant adverse effects of large masses, the authors' preference is to involve a multidisciplinary team to achieve a more comprehensive excision while minimizing the risk of potential complications.

Keywords: Femoral vessels; Hip resurfacing; Metallosis; Pseudotumor; Total hip arthroplasty; Vascular compression.

Fig. 1

Select preoperative images: A anteroposterior (AP) pelvis radiograph following index right THA; B AP pelvis radiograph prior to revision demonstrating soft-tissue shadowing and mineralization surrounding the right hip and proximal femur (arrow); C, D axial MRI slices revealing significant pseudotumor extension (arrows)

Fig. 2

Intraoperative images demonstrating A anterior intrapelvic pseudotumor excision; B second incision in femoral compartment (asterisks indicate pseudotumor)

Fig. 3

A Significant lateral pseudotumor with near-complete destruction of abductor musculature; B, C trunnionosis with wear and corrosion products involving the femoral neck trunnion and bore of the femoral head; D abductor mechanism reconstruction with tendo-Achilles allograft prior to proximal tensioning

Fig. 4

Immediate anteroposterior (A) and lateral (B) postoperative radiographs of right revision total hip arthroplasty following excision of extensive pseudotumor through multiple approaches

Fig. 5

Select preoperative images including A, B AP pelvis and lateral left hip radiographs demonstrating acetabular osteolysis (white arrow) and erosion of the anterior femoral neck (black arrow); C axial MRI slice with anterior pseudotumor (asterisk) abutting the posterior aspect of the femoral neurovascular bundle (arrow); D coronal CT angiogram slice again illustrating the close proximity of the pseudotumor (asterisk) to the left femoral vessels (arrow)

Fig. 6

Intraoperative images and immediate postoperative radiograph demonstrating A anterior pseudotumor (asterisk) dissection from the posterior aspect of the superficial femoral artery (arrow), profundal femoris, and femoral nerve; B the pseudotumor was ultimately taken out piecemeal to excise it safely; C pseudotumor was adherent to the anterior femoral neck and resulted in significant bone erosion; D immediate postoperative AP pelvis X-ray of the conversion to total hip arthroplasty