Abstract
Trunnion corrosion in metal-on-polyethylene THA is poorly understood, with multifactorial etiology, and the patients present with “hip pain”. We analysed the presenting symptoms and signs, intraoperative findings and the early results and complications of operative treatment. One surgeon treated 9 patients (6 male, 3 female), mean age 74 years, with the onset of symptoms at a mean of 7 years (range 3–18) after index surgery. The taper size was 12/14 in seven, 14/16 in one, and 6 degree in one hip. The preoperative mean cobalt level was 7.1 ppb (range, 2.2–12.8) and mean chromium level was 2.2 ppb (range, 0.5–5.2). MARS MRI showed fluid collection and pseudotumor in 5, fluid collection only in two, and synovitis/debris in one hip. In one patient, there was no preoperative MRI.
There were a myriad of clinical presentations: thigh rash alone in one; diffuse leg pain and hip rash in one; acute pseudo-sepsis in one; iliopsoas tendinitis and diffuse rash in one; trochanteric bursitis in one; groin pain only in one; thigh-buttock pain in two; and diffuse hip pain and limp in one patient. Intraoperatively, 6 patients had liner and ceramic (or oxidized zirconium) head exchange only. Three patients had concurrent acetabular revision: one for broken locking mechanism; one because liner was unavailable, and one had acetabular loosening. The postoperative metal levels decreased in all patients: mean cobalt 0.5 ppb (range, 0–1.8) and mean chromium 0.9 ppb (range, 0–2.6). Seven patients had good pain relief and no complications. There were two major complications requiring reoperation: acute infection at 6 weeks and patient required 2-stage reimplantation; and second patient had recurrent dislocation and was revised to a dual mobility component.
Trunnion corrosion in metal-on-polyethylene THA has several clinical presentations, including local skin rash, iliopsoas tendinitis, and other limb dysfunction. There should be a high index of suspicion and serum cobalt/chromium levels are recommended for diagnosis. The patients should be counseled about possible postoperative complications.
