• Harris Hip Score [ Time Frame: Postop, 12 weeks, 1 year, 3 years, 5 years ] [ Designated as safety issue: No ]
  

• Incidence of revisions and removals [ Time Frame: Any time ] [ Designated as safety issue: Yes ]
  

Patients that have already made the decision to undergo total hip replacement and will receive the M2a- Taper™ Hip System.

Inclusion Criteria:

• Patients having primary cemented or cementless total hip replacement for non-inflammatory degenerative joint disease (NIDJD), or any of its composite diagnoses of:

  1. Osteoarthritis,
  2. Avascular Necrosis,
  3. Traumatic arthritis,
  4. Subcapital fracture,
  5. Legg Perthes,
  6. Slipped Capital Epiphysis,
  7. Fracture of the pelvis,
  8. Diastrophic Variant
• Patients with full skeletal maturity.
• Patients undergoing unilateral total hip arthroplasty or bilateral total hip arthroplasty, either staged or simultaneously.
• Patients of all races and gender.
• Patients who are able to follow postoperative care instructions.
• Patients who are able and willing to return for follow-up evaluations.
• Patients have a preoperative total Harris Hip Score less than 70 with at least moderate pain.

Exclusion Criteria

• Patients diagnosed with inflammatory degenerative arthritis (IDJD) to include the following composite diagnoses: rheumatoid arthritis, systemic lupus erythematous, pigmented villonodular synovitis, juvenile rheumatoid arthritis and other arthritic processes of inflammatory or autoimmune etiology.
• Patients less than 18 years.
• Patients with the presence of a previous prosthetic hip replacement device (any type, including surface replacement arthroplasty, endoprosthesis, etc.) in the hip joint to be operated.
• Patients with previous Girdlestone procedures.
• Patients with above the knee amputation of the contralateral and/or ipsilateral leg.
• Patients with osteoporosis, or marked bone loss which would preclude proper fixation of the prosthesis.
• Patients who are pregnant.
• Patients with an active or suspected infection in or around the hip.
• Patients with Parkinson's disease.
• Patients with vascular insufficiency, muscular atrophy, or neuromuscular disease in the affected limb.
• Patients with severe instability or deformity of the ligaments and/or surrounding soft tissue which would prelude stability of the prosthesis.
• Patients with a highly communicable disease or diseases that may limit follow-up (e.g. immuno-compromised conditions, hepatitis, active tuberculosis, neoplastic disease, etc.).
• Patients unwilling or unable to comply with a rehabilitation program for a cemented or cementless total hip replacement or who indicate difficulty or inability to return for follow-up visits prescribed by the study protocol.
• Patients with previous hip surgery or conditions that may interfere with the total hip replacement's survival or outcome, e.g., Paget's disease, Charcot's disease, severe osteoporosis compromising bone stock (Dorr type C bone).
• Patients who qualify for inclusion in the study, but refuse consent to participate in the study.
• Patients with a "fused" hip.
• Patients who have had a total hip arthroplasty on the contralateral hip within the last year.