Safety and Efficacy of the Oxford Cementless Partial Knee System

Prospectively controlled, randomized Investigational study. Patients are asked to come in pre-operatively, surgery, 6 weeks, 6 months, 1 year, 2 years and annually until the last patient reaches their 2 year visit. Product has not been cleared for use.

Inclusion criteria

• Patients with a preoperative Knee Society Assessment Score of <70
• Patients undergoing primary partial knee arthroplasty as unilateral arthroplasty or bilateral arthroplasty, simultaneously or otherwise
• Patients diagnosed with osteoarthritis or avascular necrosis limited to the medial compartment of the operative knee joint
• Male or female patients who are at least 21 years of age at the time of surgery
• Patients with full thickness cartilage loss, with or without bone loss in the medial compartment
• Patients with functionally intact Anterior Cruciate Ligament (ACL) and Posterior Cruciate Ligament (PCL)
• Patients who needs to obtain relief of pain and/or improved function in their knee
• Patients with fixed flexion deformity <15 degrees
• Patients who are able to follow postoperative care instructions
• Patients who are willing and able to return for scheduled follow-up evaluations
• Patients in which natural alignment can be restored
• Patients who have completed a valid, Institutional Review Board (IRB) approved Informed Consent Form
• Patients with child-bearing potential who voluntarily agree to prevent pregnancy for 2 years following device implantation

Exclusion criteria

• Patients with a preoperative Knee Society Assessment Score of greater than or equal to 70
• Patients in which the device would be used to revise a failed prosthesis
• Patients who are less than 21 years of age, at the time of surgery
• Disease or damage to the lateral part of the knee that in the investigator's opinion contraindicates a partial knee replacement
• Patients diagnosed with rheumatoid arthritis or other forms of inflammatory joint disease
• Patients diagnosed with a failed upper tibial osteotomy in the operative knee
• Patients diagnosed with post-traumatic arthritis after tibial plateau fracture
• Patients who have had a patellectomy
• Patients with a flexion deformity > 15 degrees
• Patients with a fixed varus deformity > 15 degrees
• Patients who have rapid joint destruction, marked bone loss or bone resorption apparent on roentgenogram
• Patients with a fused knee on operative side(s)
• Patients who have active or suspected infection, local or systemic that, in the opinion of the investigator, may put patients at undue risk
• Patients with pre-existing condition(s) that may interfere with the survival of the implants or their outcomes, including:

• Sickle Cell Anemia
• Lower extremity muscular atrophy
• Neuromuscular disease
• Vascular insufficiency
• Metabolic Disorders which impair bone formation
• Paget's Disease
• Charcot's Disease
• Osteomalacia
• Severe Osteoporosis
• Patients with clinical conditions that may limit follow-up (in the opinion of the investigator) including:

• Immunocompromised conditions (i.e. HIV)
• Hepatitis
• Tuberculosis
• Neoplastic disease such as cancer of the prostate, lung, stomach, cervix, etc.
• Chronic renal failure
• Organ transplant (i.e. heart, liver, lung, etc.) recipients
• Known disease process that in the opinion of the investigator may limit long term (4 year) follow-up (i.e. multiple sclerosis, leukemia, lymphoma, etc.)
• Patients diagnosed with Parkinson's or Alzheimer's Disease
• Patients who have had an above-knee amputation in the contralateral leg
• Instability or deformity of the ligaments and/or surrounding soft tissue, which would preclude stability of the prostheses
• Patients with a known metal allergy
• Prisoners or, individuals who are known to be abusing drugs or alcohol or are mentally incompetent
• Patients who have received systemic steroids within the past 6 months or steroid injections into the affected knee within the previous 6 weeks prior to enrollment
• Patients who are pregnant
• Patients with severe valgus or varus knees (valgus or varus angulation of more than 20 degrees) where collateral ligament, iliotibial band, or popliteal release is required
• Patients who refuse to sign the IRB approved Informed Consent Form
• Participation in an interventional clinical research study procedure, other than a bilateral knee arthroplasty in this study, within the past 12 months
• Patients with a history of osteomyelitis or sepsis of the index knee
• Patients who require patellar resurfacing
• Patients who are not skeletally mature
• Patients who have had a total hip replacement procedure < 18 months prior to entering the study
• Patients who have had a contralateral non-study knee replacement procedure < 18 months prior to entering the study
• Patients who are found intraoperatively to have inadequate bone stock or other conditions that contraindicate a partial knee replacement