Pseudotumor formation following large-diameter metal-on-metal total hip arthroplasty —Report of two cases and literature review

We report two cases of this complication. Case 1 exhibited cystic change with fluid accumulation, and in Case 2 a semisolid mass was found. In Case 1, a high inclination angle of the cup (at 65°) was noted. In Case 2, the cup was placed at a normal inclination angle, but it was too anteverted (31°). The histopathological studies revealed that the cystic pseudotumor had more diffuse lymphocyte infiltration and perivascular lymphocyte cuffing with eosinophil and plasma cells. The semisolid mass of Case 2 had less lymphocyte infiltration. Both cases had metal debris with foreign body granuloma. In patients with residual groin pain and a palpable mass after surgery, the possibility of pseudotumor formation should be considered. Various imaging techniques, such as ultrasound, computed tomography scan, and magnetic resonance imaging, can be used to confirm the presence of such lesions. Revision with nonmetal-on-metal articulation is suggested to relieve the symptoms.
Source: Formosan Journal of Musculoskeletal Disorders - Category: Orthopaedics Source Type: research