Pseudotumor recurrence in a post-revision total hip arthroplasty with stem neck modularity: A case report

BACKGROUND This unique presentation of hip swelling is only the seventh reported case of pseudotumor recurrence in a non-metal-on-metal total hip arthroplasty (THA) construct. The constellation of patient symptoms and laboratory findings contradict the expected elevated serum metal ion levels associated with the formation of pseudotumor. The presentation, lab trends, and imaging findings contribute to the growing base of knowledge surrounding the effects of corrosion in arthroplasty constructs with stem-neck modularity. CASE SUMMARY A 74-year-old man status post primary THA presented with left hip swelling and elevated serum metal ions five years after implantation of a modular stem-neck prosthesis. The swelling was diagnosed as pseudotumor based on laboratory trends and imaging findings and was treated with revision arthroplasty that completely resolved the initial hip swelling. The patient presented with recurrent hip swelling and recurrent pseudotumor findings on imaging in the same hip four months later. Non-operative management with ultrasound-guided hip aspiration resulted in symptom relief and resolution of the recurrent swelling. After one year of follow-up, the patient had no further recurrences of hip swelling. CONCLUSION This case of post-revision pseudotumor recurrence elucidates attributable patient, surgical, and implant factors with a discussion of diagnostics, management, and prognosis for patients with pseudotumor in non-metal-on-metal arthroplasty constructs