Anatomic Porous Replacement hip arthroplasty: first 100 consecutive cases.

Area of Science:

• Orthopaedic Surgery
• Biomaterials Science
• Bone Physiology

Background:

• Assessing long-term fixation and bone response in hip replacements is crucial for patient outcomes.
• Understanding bone remodeling patterns around porous implants informs future design.
• The Anatomic Porous Replacement (APR) system's performance with bone ingrowth fixation requires detailed evaluation.

Purpose of the Study:

• To evaluate the fixation stability and bone remodeling of the Anatomic Porous Replacement hip implant over a 4-year period.
• To identify factors influencing bone remodeling and fixation success.
• To assess the clinical efficacy of proximal bone ingrowth fixation.

Main Methods:

• Prospective follow-up of 100 consecutive Anatomic Porous Replacement hip replacements for 4 years.
• Radiographic assessment of fixation (bone ingrowth, fibrous, loose) and bone remodeling (hypertrophy, stress shielding).
• Statistical analysis of relationships between bone type, prosthetic fill, stem-bone ratio, collar loading, and bone remodeling.

Main Results:

• 80% achieved bone ingrowth fixation, 14% stable fibrous, 6% unstable fibrous, with 4% revision rate.
• Bone remodeling, including cortical hypertrophy, was observed, with 7% experiencing stress shielding.
• Adaptive bone remodeling was strongly associated with bone type (B and C), prosthetic fill, stem-bone ratio, and collar loading.

Conclusions:

• Proximal bone ingrowth fixation with proximal load transfer yields favorable clinical results and bone remodeling.
• Collar loading positively influences bone response around the implant.
• Geometry modifications in the Anatomic Porous Replacement II aim to improve fixation predictability in diverse bone types.