Are powder-technology-built stems safe? A midterm follow-up registry study

Area of Science:

• Orthopedic surgery
• Biomaterials science
• Additive manufacturing

Background:

• Titanium powder technology aims to combine mechanical properties with high porosity.
• High porosity in implants theoretically may compromise mechanical resistance.
• Limited literature exists on the safety and use of additive manufactured cementless femoral implants, specifically electron beam melting (EBM).

Purpose of the Study:

• To evaluate the survival rates of the first two EBM-built cementless femoral stems.
• To assess the reasons for revision, focusing on implant breakage.
• To compare EBM stems against traditional cementless stems using a joint arthroplasty registry.

Main Methods:

• Utilized the Prosthetic Orthopedic Implant (RIPO) registry for cementless stems implanted between 2010 and 2017.
• Compared EBM-manufactured stems (Parva and Pulchra) against all other cementless stems as a control group.
• Assessed survival rates and reasons for revision for both cohorts.

Main Results:

• No instances of stem breakage were reported in the EBM group.
• At 5-year follow-up, survival rates were statistically similar: 96.8% for EBM stems and 98.0% for standard cementless stems (p > 0.05).
• Aseptic loosening was observed in 1.7% of EBM stems at the latest follow-up.

Conclusions:

• This study indicates that mechanical resistance is not a concern for EBM stems at mid-term follow-up.
• Findings suggest EBM technology is a viable option for cementless femoral implants.
• Further validation with larger patient cohorts and longer follow-up periods is recommended.