The objective of this study is to gather clinical and survivorship information for the C2a-Taper™ Acetabular System, a ceramic-on-ceramic hip articulating system.

Study Design:

Phase 1

Sites will collect the following types of data:

Clinical-Total Harris Hip Score, Radiographic Evaluation- measurements on acetabular and femoral components Survivorship-removal/revision of one or more components (i.e. liner, head, shell and/or stem) Safety- All other adverse events

Follow-up Visit schedule

• 6 week ± 2 weeks
• 6 month ± 1 month
• 1 year ± 3 months
• 2 years ± 3 months
• 3 years ± 3 months
• 4 years ± 3 months
• 5 years ± 3 months

Phase 2:

Patients continue to be followed on an annual basis (Years 6-10) via mail. A self assessment form is sent directly to the subject on an annual basis starting in the 6th post-operative year.

Inclusion Criteria:

• Skeletally mature patients with non-inflammatory degenerative joint disease such as osteoarthritis, avascular necrosis, congenital hip dysplasia, and traumatic arthritis

Exclusion Criteria:

• Patients with: Osteoporosis, metabolic disorders, osteomalacia, rapid joint destruction, vascular insufficiency, muscular atrophy, and neuromuscular disease

Multi-Center study conducted in the United states on patients who meed the inclusion / exclusion criteria identified in the protocol.