Gamma Vacuum Foil (GVF) Versus Cross-linked Polyethylene in Total Knee Arthroplasty Study

In 1996, Gamma Vacuum Foil (GVF) polyethylene was introduced as the first polyethylene to be gamma irradiated and packaged in an inert environment. This polyethylene, with its patented process and packaging, continues to be the only barrier-packaged process that is impermeable to both Hydrogen (H2) and Oxygen (O2), and allows the polyethylene to recombine and cross-link in the package. Though the new moderately cross-linked polyethylene being evaluated in this protocol is comparable to GVF geometrically and mechanically, the P.F.C.® Sigma™ cross-linked polyethylene also has the added benefit of being completely oxidatively stable both on the shelf and in-vivo.

The P.F.C. Sigma tibial tray component being assessed in this study is made of Cobalt Chrome (CoCr). The new CoCr tibial tray has the same design geometrically as the original titanium (Ti) tray, however, it features a highly polished top surface where it is joined to the polyethylene. This polished surface is designed to decrease the coefficient of friction between the polyethylene and the tray, thus minimizing backside wear. A comparative clinical study will be conducted to evaluate long-term clinical and radiographic data between geometrically identical cemented implants using GVF and crosslinked polyethylene tibial tray bearing inserts in Total Knee Arthroplasty (TKA) using the P.F.C. Sigma Total Knee System. Patients will be assigned to study treatment groups at random if they meet specific demographic and pathophysiologic criteria for cemented total knee arthroplasty. The anticipated duration of this investigation is a minimum six years, which includes a one-year enrollment phase.

The specific aims of this study are as follows:

• Examine whether crosslinked polyethylene performs as well, if not better, than GVF polyethylene through standard clinical evaluations.
• Evaluate long-term survivorship rates.
• Report complications/adverse events.
• Report radiographic findings of geometrically identical implants.

Inclusion criteria

• Osteoarthritis of the affected joint appropriate for Total Knee Arthroplasty.
• Diagnosis of any of the following: rheumatoid or other inflammatory arthritis, post-traumatic arthritis, juvenile rheumatoid arthritis.
• Radiographic evidence of sufficient sound bone stock to seat and support the prosthesis.
• Subject requires a primary total knee replacement and is considered to be suitable for the specific knee prosthesis identified in protocol.
• Subject has given consent to the transfer of his/her information to sponsor.
• Subject will be compliant with requirements of protocol by returning for follow-up visits.

Exclusion criteria

• History of recent/active joint sepsis.
• Charcot neuropathy.
• Psycho-social disorders that would limit rehabilitation.
• Women who are pregnant or planning on being pregnant.
• Greater than 80 years of age at the time of surgery.
• Prior ipsilateral knee arthroplasty.
• Metabolic disorders of calcified tissues, such as Paget's disease.
• Severe diabetes mellitus that is not controlled by diet or oral agents.
• Require joint replacement due to immunodeficiency syndromes.
• Skeletal immaturity.
• Avascular necrosis of the affected knee.
• Chronic renal disease.
• Subjects involved in medical-legal or worker's compensation claims.