The purpose of this study is to evaluate a hip implant system used when a previous hip replacement surgery has failed.

Total hip replacement is considered to be a very successful surgical procedure for the treatment of degenerative joint disease. Clinical results for cementless acetabular components have demonstrated excellent long-term fixation of these devices. However, so called 'first generation' cementless acetabular components have not had similar success rates. In these cases the acetabular component is often revised due to loosening, wear or infection.

Revision hip arthroplasty also becomes a challenge as patients often present with severe bone loss and poor bone quality. This can lead to compromised initial stability, which in turn leads to lack of long-term fixation and failure. Acetabular revision with a cementless component has shown improved results over cemented fixation.

Radiographic evaluation of the Trident® Tritanium™ Acetabular Shell will provide valuable early to intermediate information that may help predict the long-term success of this new system.

It is the intention of this study to closely follow subjects that have undergone revision hip replacement with regard to implant survivorship, signs of radiographic loosening, subjects' function evaluated through Harris Hip Score and Lower Extremity Activity Scale, subject quality of life through SF-36 and adverse events.

The primary efficacy hypothesis is that the rate of revision or pending revision (as defined by radiographic parameters) due to instability or lack of fixation for the Trident® Tritanium™ Acetabular Shell will be less than 10% at 5 years.

Inclusion Criteria:

1. Males and non-pregnant females, 21-85 years of age at the time of surgery.
2. Patient is a candidate for a revision of a failed acetabular component with a cementless acetabular component.
3. Patient has signed an IRB approved study consent form.
4. Patient is willing and able to comply with postoperative requirements including postoperative weight bearing restrictions and self-evaluations.

Exclusion Criteria:

1. Patient is morbidly obese, BMI > 40.
2. Patient has a systemic or metabolic bone disorder leading to progressive bone deterioration.
3. Patient is immunologically compromised or receiving steroids in excess of normal physiological requirements (> 30 days).
4. Patient's bone stock is compromised by disease or infection which cannot provide adequate support and/or fixation to the prosthesis.
5. Patient has an active or suspected latent infection on or about the hip joint.
6. Patient is a prisoner.