Pseudotumor-Related Compression Neuropathies Following Total Hip Arthroplasty.

Abstract

Pseudotumor-related compression neuropathies following total hip arthroplasty (THA) represent a severe phenotype of adverse local tissue reaction. While historically attributed to metal-on-metal (MoM) bearings, other constructs such as dual-modular necks and taper corrosion with cobalt-chrome femoral heads have been implicated as well. Furthermore, inflammatory responses to polyethylene wear debris and non-foreign body sources can similarly stimulate pseudotumor formation, resulting in symptomatic nerve compression. This study aimed to characterize the etiology, clinical presentation, and surgical outcomes of patients who have pseudotumor-induced neuropathies. A retrospective review identified 83 patients who had a pseudotumor or local mass effect of 9,042 revision THA performed between 1997 and 2024. There were 24 patients (25 hips) who had a confirmed pseudotumor-related compression neuropathy. Implant characteristics, serum biomarkers, neurologic deficits, and clinical outcomes following surgical intervention were studied. Taper corrosion (n = 11), MoM articular wear (n = 4), and dual-modular neck corrosion (n = 4) were the predominant pseudotumor etiologies. Seronegative pseudotumors were observed in a subset of patients who presented with normal serum metal ions and inflammatory markers, despite massive soft-tissue lesions. Presenting neurologic deficits were complete in six cases and partial in 19 (motor: n = 15, sensory: n = 4), involving the femoral (n = 8), gluteal (n = 7), sciatic (n = 6), and peroneal (n = 4) nerves. Following revision THA and neurolysis, motor recovery was variable, with complete sciatic or peroneal division neuropathy resulting in persistent foot drop in four of five cases. Postoperative dislocation requiring revision surgery was seen in five cases. Pseudotumor-related neuropathy is a distinct complication observed across various implant designs and modular interfaces. Normal serum ion levels do not exclude the diagnosis. While surgical decompression is effective for pain relief, motor recovery is poorly predictable, carrying a guarded prognosis.