Failure of the Ring polyethylene uncemented acetabular cup

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Pathology

Background:

• The Ring prosthesis is a cementless acetabular component used in hip arthroplasty.
• Polyethylene wear and osteolysis are known complications in total hip replacement.

Purpose of the Study:

• To evaluate the long-term failure rate and complications associated with the Ring polyethylene cementless cup.
• To investigate the incidence and characteristics of granulomatous osteolysis in relation to this prosthesis.

Main Methods:

• Retrospective review of 126 Ring prostheses implanted between 1986 and 1992.
• Radiological assessment for osteolytic granulomas and clinical follow-up for revision rates.
• Histological examination of retrieved prostheses for polyethylene wear debris.

Main Results:

• A high incidence of radiological osteolytic granulomas (32% overall, 54% at >=4 years).
• 22% of cups required revision, primarily for granulomatous loosening (21 cases).
• Retrieved cups showed significant polyethylene abrasion and wear debris.

Conclusions:

• The Ring polyethylene cementless cup demonstrates a high failure rate attributed to granulomatous osteolysis.
• Polyethylene wear debris is a key factor in the development of osteolysis and loosening.
• Further research into alternative bearing surfaces or implant designs may be warranted.