title: Fracture of the cobalt-chromium modular femoral neck component in total hip arthroplasty.
abstract: Total hip prostheses using cervico-metaphyseal modularity were designed to better replicate the geometry of the native extra-medullary femur. However, they are associated with numerous complications including corrosion, disassembly, pseudotumours and, most notably, fractures of the modular neck. All reported cases of modular neck fractures occurred with titanium components (Ti-6Al-4V). To prevent this weakness, manufacturers developed modular necks made of cobalt-chromium (Co-Cr). We report a fracture of a long, 8° varus, Co-Cr modular neck connected to a 36-mm short (-3.5mm) femoral head. The fracture occurred 22 months post-implantation in a woman who had a low level of physical activity and a body mass index of 28.7 kg/m(2). To our knowledge, this case is the first reported instance of Co-Cr modular neck fracture. It may challenge the wisdom of further developing this modularity design, as our patient had none of the known risk factors for modular neck fracture. In addition, cases of pseudotumour have been reported with Co-Cr modular necks subjected to fretting corrosion, which contributed to the fracture in our patient.
authors.affiliation: Service de chirurgie orthopédique et traumatologique, CHU d'Amiens, hôpital Nord, 1, place Victor-Pauchet, 80054 Amiens, France. Electronic address: maximemenciere@gmail.com.
authors.forename: M-L
authors.initials: ML
authors.lastname: Mencière
authors.affiliation: Service de chirurgie orthopédique et traumatologique, CHU d'Amiens, hôpital Nord, 1, place Victor-Pauchet, 80054 Amiens, France.
authors.forename: T
authors.initials: T
authors.lastname: Amouyel
authors.affiliation: Service de chirurgie orthopédique et traumatologique, CHU d'Amiens, hôpital Nord, 1, place Victor-Pauchet, 80054 Amiens, France.
authors.forename: J
authors.initials: J
authors.lastname: Taviaux
authors.affiliation: Service de chirurgie orthopédique et traumatologique, CHU d'Amiens, hôpital Nord, 1, place Victor-Pauchet, 80054 Amiens, France.
authors.forename: M
authors.initials: M
authors.lastname: Bayle
authors.affiliation: Service de chirurgie orthopédique et traumatologique, CHU d'Amiens, hôpital Nord, 1, place Victor-Pauchet, 80054 Amiens, France.
authors.forename: C
authors.initials: C
authors.lastname: Laterza
authors.affiliation: Service de chirurgie orthopédique et traumatologique, CHU d'Amiens, hôpital Nord, 1, place Victor-Pauchet, 80054 Amiens, France.
authors.forename: P
authors.initials: P
authors.lastname: Mertl
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002857:Chromium; D003035:Cobalt; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D011475:Prosthesis Failure
chemical_list: D002857:Chromium; D003035:Cobalt
keywords: Cobalt-chromium; Corrosion; Fracture; Hip prosthesis; Modular neck