The purpose of this study is to evaluate the efficacy and safety of the Sirius Cemented Stem used in conjunction with the Exceed ABT Cemented Acetabular Cup, either with E1 or Arcom polyethylene, and OptiPac/OptiVac bone cement mixing systems.

This is a comparative, prospective randomized Radiostereometry (RSA) study, lead on 48 patients in a single site.

All 48 patients will be pooled in a single group for the evaluation of the primary criterion for evaluation, but randomized into four groups for the evaluation of the secondary criteria for evaluation

The objectives of the study are to:

1. Demonstrate a comparable migration pattern as is described in published literature on other double tapered polished cemented stems
2. Measure wear pattern in the cup made of vitamin-E doped polyethylene or conventional Arcom polyethylene

2)Demonstrate non-inferiority of Optipac vs. Optivac cement mixing systems on the stem side 3)Evaluate the clinical outcome and survivorship of the implant

Inclusion Criteria:

1. Patients who are eligible for cemented total hip arthroplasty
2. Patients diagnosed with primary Osteoarthritis
3. Patients who are fit for elective surgery (ASA I - III)
4. Patients with a BMI between 16 and 40
5. Patients who are skeletally mature
6. Patients aged over 18 at the time of surgery
7. Patients willing to return for follow-up evaluations
8. Patients who have the ability to follow instructions
9. Patients with sufficient bone stock and quality

Exclusion Criteria:

1. Female patients who are pregnant or planning pregnancy during the course of the study (no use of adequate birth control)
2. Patients with diagnosed active infection
3. Patients with marked bone loss which could preclude or compromise adequate fixation of the device
4. Patients with Parkinson disease
5. Patients using immunosuppressive drugs
6. Patients with an immunosuppressive disease
7. Patients with BMI <16
8. Patient with BMI >40
9. Patients who are unfit for surgery (ASA IV - V)
10. Patients with acetabular or femoral osteotomy
11. Patients who had a THA on the contralateral side within last 6 months
12. Patients belonging to the vulnerable population: children, patients with mental