A Validated Necrosis Assay to Determine the Need for Revision Surgery in Metal-on-metal Total Hip Arthroplasty

Well-functioning MoM implants have shown an increase in serum cobalt and chromium (CoCr) ion
levels from the metal debris generated from the implant wear.However, the current evidence
suggests that measuring ion levels is unreliable and that increasing ion levels do not
correlate with tissue damage. In addition to measuring blood and synovial fluid metal ion
levels, ultrasound and MRI with metal artifact reduction sequences (MARS) have been utilized
to assess periarticular reactions secondary to metal wear debris. Despite metal reduction
software these scans are frequently difficult to interpret. While each of these tests has
merit, at the present time there is no single diagnostic test available which delineates the
key issue that demands urgent surgical intervention, i.e. tissue necrosis. It is important to
have a reliable test to guide surgeons and patients in the shared decision-making process of
when surgical intervention is necessary to prevent disabling tissue damage. For this reason,
the current study proposes an examination of preoperative serum samples of subjects in
addition to synovial fluid collected during revision surgery for biomarkers that may indicate
tissue necrosis. To maximize the chance of success of identifying serum biomarkers, all
samples will be analyzed using multianalyte assay, biomarker tests. The purpose of the study
is to develop a biomarker assay to be used as a diagnostic tool for adverse local tissue
reaction, or tissue necrosis, in a metal on metal total hip replacement.

A convenience sample of a total of 100 hip patients will be enrolled: 50 metal-on-metal
revision hips, 25 metal-on-poly revision hips, and 25 pre-operative total hips (no implant,
control group) will be enrolled. Preoperative blood serum samples and intraoperative synovial
fluid will be obtained from all hips and used for biomarker testing. Additionally,
intraoperative assessment of tissue necrosis will be assessed.

Inclusion Criteria:

- Patients presenting for a metal on metal hip revision who have cobalt and chromium
metal ion levels tested within 6 months of the date of the planned revision surgery.

- Patients presenting for a metal on poly hip revision

- Revision hip patients must be greater than one year postoperative

- The diagnosis at the time of the index, or primary, hip replacement was
osteoarthritis.

- Patients who have hip osteoarthritis but have not had a total hip surgery (control)

Exclusion Criteria:

- Patients presenting for a metal on metal hip revision who have cobalt and chromium
metal ion levels tested >6 months of the date of the planned revision

- Patients with a total hip on the contralateral side.

- Patients with a prior history of periprosthetic infection

- Revision cases where the diagnosis at the time of the index, or primary, hip
replacement was not osteoarthritis.

- Prisoners

- Patients not willing to consent for the proposed treatment

- Patients with an altered mental status

- Active, concurrent metastatic infection

- Active, superficial infection

- Patients presenting for a metal on poly hip revision to treat trunionosis