Maxim® Knee Pop-Top® Tibia vs. Regular Maxim® Knee Tibia

Inclusion Criteria: Identical to the indications stated in the FDA approved labeling for the device (cleared in 510(k) K991753, K984623, K993159, K010027). These indications are stated below: * Painful and disabled knee joint resulting from osteoarthritis, rheumatoid arthritis, traumatic arthritis where one or more compartments are involved. * Correction of varus, valgus, or posttraumatic deformity. * Correction or revision of unsuccessful osteotomy, arthrodesis, or failure of previous joint replacement procedure. Patient selection factors to be considered include: * need to obtain pain relief and improve function, * ability and willingness of the patient to follow instructions, including control of weight and activity level, * a good nutritional state of the patient, * the patient must have reached full skeletal maturity. * Porous coated knee joint replacement prostheses have not been approved for non-cemented applications in the United States. Exclusion Criteria: Identical to the contraindications stated in the FDA approved labeling for the device (cleared in 510(k) K991753, K984623, K993159, K010027's). These contraindications are stated below: Absolute contraindications include: * infection, * sepsis * osteomyelitis. Relative contraindications include: * uncooperative patient or patient with neurologic disorders who are incapable of following directions, * Osteoporosis, * metabolic disorders which may impair bone formation, * osteomalacia, * distant foci of infections which may spread to the implant site, * rapid joint destruction, marked bone loss or bone resorption apparent on roentgenogram, * vascular insufficiency, muscular atrophy, neuromuscular disease, * incomplete or deficient soft tissue surrounding the knee.