Retrieval Analysis of Neck-Stem Coupling in Modular Hip Prostheses.

Area of Science:

• Orthopedic surgery
• Biomaterials science
• Medical device analysis

Background:

• Dual-taper modular stems have high revision rates due to tissue reactions from fretting and corrosion.
• A recalled modular neck design (Rejuvenate) is compared against seven other designs.

Purpose of the Study:

• To compare fretting and corrosion behavior across different modular neck designs.
• To evaluate the incidence of aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) in retrieved implants.

Main Methods:

• Analysis of fretting and corrosion in 60 Rejuvenate and 26 other retrieved modular neck-stem implants.
• Histological grading of aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) in tissue samples.
• Multivariate analysis to identify factors influencing fretting, corrosion, and ALVAL.

Main Results:

• The recalled Rejuvenate design exhibited significantly higher damage and corrosion scores.
• Histology revealed a 20-fold increased likelihood of ALVAL in the recalled design.
• Mixed metal couplings showed higher fretting and corrosion compared to homogenous couplings.

Conclusions:

• Fretting and corrosion are inherent to modular neck-stem implants, irrespective of design.
• Mixed metal designs are associated with increased corrosion and ALVAL.
• Clinicians are advised to avoid modular neck-stem systems due to risks of corrosion and fracture.