Corrosion at the head-neck taper as a cause for adverse local tissue reactions after total hip arthroplasty

Abstract

Background: Corrosion at the modular head-neck junction of the femoral component in total hip arthroplasty has been identified as a potential concern, although symptomatic adverse local tissue reactions secondary to corrosion have rarely been described.

Methods: We retrospectively reviewed the records of ten patients with a metal-on-polyethylene total hip prosthesis, from three different manufacturers, who underwent revision surgery for corrosion at the modular head-neck junction.

Results: All patients presented with pain or swelling around the hip, and two patients presented with recurrent instability. Serum cobalt levels were elevated prior to the revision arthroplasty and were typically more elevated than were serum chromium levels. Surgical findings included large soft-tissue masses and surrounding tissue damage with visible corrosion at the femoral head-neck junction; the two patients who presented with instability had severe damage to the hip abductor musculature. Pathology specimens consistently demonstrated areas of tissue necrosis. The patients were treated with debridement and a femoral head and liner exchange, with use of a ceramic femoral head with a titanium sleeve in eight cases. The mean Harris hip score improved from 58.1 points preoperatively to 89.7 points at a mean of 13.0 months after the revision surgery (p=0.01). Repeat serum cobalt levels, measured in six patients at a mean of 8.0 months following revision, decreased to a mean of 1.61 ng/mL, and chromium levels were similar to prerevision levels. One patient with moderate hip abductor muscle necrosis developed recurrent instability after revision and required a second revision arthroplasty.

Conclusions: Adverse local tissue reactions can occur in patients with a metal-on-polyethylene bearing secondary to corrosion at the modular femoral head-neck taper, and their presentation is similar to the adverse local tissue reactions seen in patients with a metal-on-metal bearing. Elevated serum metal levels, particularly a differential elevation of serum cobalt levels with respect to chromium levels, can be helpful in establishing this diagnosis.

Fig. 1

Axial T1-weighted fat-suppressed MRI demonstrating a large fluid collection within the hip joint (arrowheads).

Fig. 2

Intraoperative photograph demonstrating corrosion (arrow) at the modular head-neck taper between the femoral component and a collared (+10.5-mm) head. The pseudocapsule is markedly hypertrophic and avascular (asterisk), which is typical of this adverse local tissue reaction.

Fig. 3

Case 8. Photomicrograph of the pathology specimen (hematoxylin and eosin, ×125). Viable areas of the joint pseudocapsule demonstrated a dense perivascular infiltration of lymphocytes. Large areas of the specimen were necrotic (not visualized on this image).

Fig. 4

Graph depicting the decrease in serum cobalt levels following revision surgery for corrosion at the modular head-neck taper. The square represents the mean of the preoperative values for the six patients who had measurement of postoperative metal levels. The triangles represent individual data points for different patients at various points during the postoperative course. As a reference, patients with a well-functioning metal-on-polyethylene total hip prosthesis have demonstrated a serum cobalt level of 0.16 ± 0.10 ng/mL at eighty-four months postoperatively.