Abstract
Introduction
Taper corrosion at modular junctions can cause a spectrum of adverse local tissue reactions (ALTR) in the periprosthetic soft tissues in patients who have undergone total hip arthroplasty (THA). Because these reactions are usually painful, taper corrosion has become part of the differential diagnosis of hip pain following THA. However these destructive lesions may not always cause pain, and can occasionally result in other atypical presentations. The purpose of this study is to describe a cohort of patients presenting with late and recurrent instability following THA due to underlying ALTR and taper corrosion.
Methods
This is a multicenter retrospective case series of fourteen patients presenting with late instability secondary to ALTR and corrosion at the modular head-neck taper. The cohort included nine women and five men with a mean age of 66.8 years (range, 49 to 74). All patients had a metal (CoCr)-on-polyethylene bearing surface, but had a range of CoCr and Ti-alloy stem designs from three different manufacturers. Seven patients had 28 mm heads, while the rest had 32–40 mm heads. Patients experienced a mean of 3.4 dislocations (range, 2 to 6) at an average of 5.2 years (range, 0.4 to 17.0) following their index surgery. Although most reported some degree of discomfort around the hip, instability was the primary presenting symptom in all fourteen patients, and four were otherwise completely asymptomatic. Serum metal levels demonstrated a greater elevation of cobalt (mean 3.13 ng/mL) than chromium (mean 2.33 ng/mL). Preoperative infection workup including serum inflammatory markers and a hip aspiration documented the absence of sepsis.
Results
Radiographic analysis demonstrated cups were well positioned, with a mean abduction angle of 43.2° (range, 40° to 48°) and mean anteversion angle of 19.5° (range, 16° to 26°). Hips were revised at a mean of 7.4 years (range, 2.4 to 19.4) following their index surgery. At the time of revision, ALTR was encountered in every case, with extensive tissue necrosis and abductor damage or insufficiency in the majority. The modular head-neck junction demonstrated visible corrosion seen as fretting, surface damage, and deposition of a black, flaky material. Constrained liners were placed in all patients.
Conclusions
Although ALTR resulting from modular taper corrosion typically presents with hip pain, some patients can present with recurrent instability in the absence of other significant symptoms. Recurrent instability in the setting of otherwise well-positioned components and without another obvious cause should raise concern for ALTR as a potential underlying etiology.
