Prospective Randomized Study of Cementless vs Cemented UKA

Inclusion Criteria: * Patients with a pre-operative 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 (Kellgren Lawrence Grade IV) 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 ACL and PCL * Patients who need to obtain relief of pain and/or improved function in their knee * Patients with fixed flexion deformity \< 15° * Patients who are able to follow post operative care instructions * Patients who are willing and able to return for scheduled follow-up evaluations * Patients in which natural alignment can be restored * Patients with BMI \< 40 * Patients who have completed a valid, IRB approved Informed Consent Form Exclusion Criteria: * Patients with a pre-operative Knee Society Assessment Score of ≥ 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° * Patients with a fixed varus deformity \> 15° * Patients who have rapid joint destruction, marked bone loss or bone resorption apparent on roentgenogram * Patients with a fused knee on operative side * Patients who have active or suspected infection, local or systemic that, in the opinion of the investigator, may put patients at undue risk. * Patient with pre-existing condition(s) that may interfere with the survival of the implant 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, Osteoporosis, Osteopenia. * Patients with clinical conditions that may limit follow-up (in the opinion of the investigator) including: Immuno-compromised 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 injection into the affected knee within the previous 6 weeks prior to enrollment * Patients taking immunosuppressives * Patients who are pregnant and/or breast-feeding females or females who intend to become pregnant during the time of the study * Patients with severe valgus or varus knees (valgus or varus angulation of more than 20°) 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 * Patients who have a higher risk of falling * Patients who are smokers or a history of smoking in the past 12 months * Patients with alcoholism or drug addiction * Tumors of the supporting bone structures * Patients who have a permanent valgus or varus deformity including tibia vara deformity * Patients with BMI ≥ 40 * Patients 80 years of age or older * Patients who have undergone same-day or staged bi-lateral partial knee replacement * Patients who may have an allergic reaction to the device materials or bone cement