Abstract
Introduction
Corrosion at the modular junction of the femoral component in total hip arthroplasty (THA) was considered as a cause of adverse local tissue reaction in recent years. We reported three adverse local tissue reaction cases after total hip arthroplasty using the same modular neck stem in this study.
Materials and Methods
We have been essentially using the same titanium modular neck stem system and the same combination bearing surface of 26mm cobalt chromium (CoCr) head and highly cross linked polyethylene line for primary total hip arthroplasty since November 2009. Three female showed adverse local tissue reaction and had additional surgical treatment after the THA.
Results
Two patients showed asymptomatic focal osteolysis on X-ray at the Gruen zone 1 around three years after the THA (one case also showing pseudo tumor around lessor trochanter). One patient presented symptomatic deep vein thrombosis (DVT) suddenly four years after the surgery and was detected massive pseudo tumor around the hip in MRI. High serum cobalt level was detected in two pseud tumor cases (9.3 ng/ml in DVT case, 5.0 ng/ml in an osteolysis case). The patients had debridement of pseudo tumor and osteolysis. The 26mm CoCr head was replaced a delta ceramic head with a new neck and liner. Two osteolysis cases were grafted allogenic bone chips. Pathology specimens showed tissue necrosis. All retrieved head and neck component showed some corrosion only at the modular of head neck junction. High level of cobalt (2.43 mg/100g) and chromium (4.60 mg/100g) were detected in necrotic tissue of DVT case by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) analysis.
Discussion and Conclusion
This study showed adverse local tissue reaction could occur in spite of using small metal head and polyethylene bearing secondary to corrosion at the taper. It is thought that head neck junction corroded due to mechanically assisted crevice corrosion. An incidence of adverse local tissue reaction of this titanium modular stem might be lesser 0.2% (3/2600 over) in our institute. However, we began to stat new combination of bearing surfaces, ceramic head and polyethylene liner, even so extremely low incidence of adverse local tissue reaction derived from cobalt chromium alloy.
