The purpose of this prospective study is to evaluate Zimmer® iASSIST™ with respect to radiographic, clinical and economic outcomes and compared to conventional instrumentation in primary total knee arthroplasty (NexGen or Persona knee implants).

The study design is a prospective, multicenter, comparative outcome study. The study requires each site to obtain IRB (Institutional Review Board) approval prior to study enrollment. All potential study subjects will be required to participate in the Informed Consent Process.

All study subjects will undergo preoperative clinical evaluations prior to their total knee arthroplasty. Investigators will collect clinical data for 12 months. Follow-up clinical visits include 3 and 12 months post-operatively.

The primary endpoint of this study is defined as component alignment as determined using long leg X-Rays. The secondary endpoint will be to evaluate the Knee Society Score, EQ-5D (EuroQol-5Dimensions) scoring system, operating room time, blood loss and complications

Inclusion Criteria:

• Patient is male or female

• Patient needs a primary total knee replacement using the NexGen LPS Flex or Persona knee implant

• Patient is diagnosed with non-inflammatory degenerative joint disease (e.g., osteoarthritis, post-traumatic arthritis, avascular necrosis, etc.)

• Patient is over 18 years old

• Patient is able to:

  • Understand what participation in the study entails and willing to consent (patient or his/her legal guardian) to participate in the study by signing and dating an IRB/EC (ethics committee) approved inform consent form, and
  • Follow surgeon/staff instructions, and
  • Return for all follow-up evaluations, and
  • Able and willing to undergo a preoperative full-leg, standing radiographs and/or CT-scan

• Patient meets an acceptable preoperative medical clearance and is free of or treated for cardiac, pulmonary, hematological or other conditions that would pose excessive operative risk.

• Patient has a presence of varus or valgus deformity of 15 degrees or less.

Exclusion Criteria:

• Patient is currently enrolled in an investigational new drug or device study.
• Patient has an active infection (including septic knee, distant infection, or osteomyelitis).
• Patient has severe hip arthrosis.
• Patient has neurological disorders (including, but not limited to Parkinson's disease).
• Patient has had a prior ipsilateral unicompartmental knee arthroplasty, TKA, knee fusion or patellectomy.
• Patient has hip or knee ankylosis.
• Patient has inflammatory joint disease.
• Patient has rheumatoid knee arthritis.
• Patient has indications of intra- and/or extra-articular deformations that would eliminate or tend to eliminate adequate implant support or prevent the use of an appropriately sized implant, such as polio, history of tibial plateau fracture, etc.
• Patient has any metal within 150 mm of the joint line for the operative-side knee.
• Patient has knee deformities greater than 15 degrees of fixed varus, valgus, or flexion contracture on initial physical examination.
• Female who is pregnant or lactating.
• Patient currently involved in any personal injury litigation, medical-legal or worker's compensation claims.
• Patient has arterial disease or stents that would exclude the use of a tourniquet.
• Patient has insufficient quality or quantity of bone to support the implant due to prior knee surgery (or surgeries), cancer, metabolic bone disease, osteoporosis/osteopenia (diagnosed or treated with medication), active/old/remote infection, etc.
• Patient has a mental condition that may interfere with his/her ability to give an informed consent or interfere with his/her ability or willingness to fulfill the requirements of the study.
• Patient has a condition that would place excessive demands on the implant (e.g., Charcot's joints, muscle deficiencies, multiple joint disabilities, skeletal immaturity, etc.).
• Patient has collateral ligament insufficiency.
• Patient has an immunosuppressive disorder (e.g., AIDS, etc.) that would require cytotoxic drugs, corticosteroids, large dose of irradiation, or antilymphocytic serum.
• Patient has an existing condition that would, in the opinion of the investigator, compromise participation or follow-up in this study.

The adverse events were collected preoperatively, intraoperatively and postoperatively (at 3 months ±2 weeks and 12 months ±1 month postoperative).

Since the first follow-up visits were performed according to the standard of care of each site, they did not occur at the same time point.

Study patients will not know if their knee prosthesis will be implanted with iAssist or with conventional instrumentation