The purpose of this study is to document and compare the surgical and after surgery costs, recovery time, and outcomes of two procedure types:

• Robotic assisted surgery replacing one compartment of the knee
• Manual (robot is not used) surgery replacing all three compartments of the knee (total knee replacement)

The hypothesis is that robot assisted partial knee replacement is cost effective and provides clinical outcomes that are equivalent to a manual total knee replacement.

Background and Significance:

The primary indications for joint replacement surgery include severe lower extremity pain that prevents individuals from performing normal daily activities. The level of pain experienced by these patients cannot be managed successfully with oral medications, physical therapy, or joint injections of steroids or hyaluronic acid. The source of the pain most commonly is a result of arthritic changes in the joint; the arthritis may be due to osteoarthritis, rheumatoid arthritis, or traumatic arthritis. Patients who are appropriate candidates for partial joint replacement surgery also may experience joint stiffness that interferes with their normal daily activities. In addition, there usually is radiographic evidence of changes in the joint caused by the arthritic process. Joint damage is evaluated radiographically in order to classify the severity of the joint disease. Partial joint replacement surgery is performed to replace the diseased parts of the joint with prosthesis. There are a variety of options that surgeons and patients can choose for their joint replacement surgery. There are many different joint replacement component systems manufactured by several different companies; some systems are recommended for particular types of patients while others can be used in a greater number of patients. Recently, new techniques have been introduced that are classified as minimally invasive because they require smaller surgical incisions to implant standard joint prostheses. Patients who are younger, thinner, and in better overall health are usually the best surgical candidates for minimally invasive procedures.

Osteoarthritis affects 40 million Americans and 15 million people in the United States suffer from degenerative arthritis of the knee. Unicondylar knee arthroplasty (UKA) was introduced as a treatment option for degenerative arthritis of the knee in the early 1970's[1]. The procedure initially yielded variable results and this unpredictability resulted in broadly low levels of usage[1]. Recent improvements in the surgical techniques and technology used for UKA have increased the effectiveness of this surgery. As the average age of the United States population increases, this surgical procedure will become even more common. It is estimated by the Millennium Research Group that there will be 55,100 unicondylar knee procedures in 2010 and the compound annual growth rate from 2009 to 2014 will be 8.3%.

UKA knee arthroplasty can be viewed as an attractive alternative to total knee arthroplasty (TKA) assuming the patient's osteoarthritis has remained isolated in a single compartment or two compartments. UKA knee arthroplasty are generally less invasive procedures than TKA. Since the procedure is less invasive there is usually less blood loss; more cartilage, tissue, and bone is sparred, which results in shorter recovery times than TKA. This procedure is attractive to adults who are interested in remaining active pain-free lifestyles as they age.

The cost-effectiveness of healthcare interventions, especially new technology, is becoming essential. Comparing the procedural costs of robotic-assisted surgery and the outcomes of the patients versus TKA, the gold standard, will help substantiate whether robotic-assisted surgery from an economic viewpoint is a cost-effective treatment. In addition the rehabilitation after knee replacement surgery is critical to achieving proper functional outcomes. Information pertaining to knee replacement post discharge costs has been limited. Due to the lack of studies and the continued growth in the number of knee arthroplasty surgeries it is imperative to track post discharge costs of all variables. We will be documenting and comparing the procedural and postoperative costs, recovery time, and outcomes of three procedure types in robotic assisted unicompartmental knee arthroplasty, robotic assisted bicompartmental knee arthroplasty and manual total knee arthroplasty.

Inclusion Criteria:

• Age, 21-80 years
• Sex, males and females will be included
• BMI less than or equal to 39
• Stable health, the patient would be able to undergo surgery and participate in the follow-up program based on physical examination and medical history
• Patient is willing and able to cooperate in follow-up therapy at Rebound facilities in Vancouver, WA
• Patient has stable and functional collateral ligaments
• Patient or patient's legal representative has signed the Informed Consent form
• Failed non-operative management of their joint disease
• Need to obtain pain relief and improved function
• Moderate or severe pain with either walking or at rest
• Diagnosed with osteoarthritis in one or more compartments of the knee and non-surgical treatment options have failed to provide relief for symptoms
• Patient exhibits preoperative radiographic evidence of joint degeneration that cannot be treated in non-operative fashion

Exclusion Criteria:

• Patients who, in the opinion of the Investigator, have an existing condition that would compromise their participation and follow-up in the study
• Patients with pre-op flexion contracture greater than 10 degrees, overall flexion less than 115 degrees, and varus/valgus greater than 10 degrees
• Patient who is on workmen's compensation
• Patients who are on chronic long acting preoperative narcotic pain medication
• Patients with inflammatory polyarthritis
• Women who are pregnant
• Subjects who are known drug or alcohol abusers or with psychological disorders that could effect follow-up care or treatment outcomes
• Subjects who are currently involved in another clinical study with the exception to an outcomes study
• Patients with a pathology which, in the opinion of the Principal Investigator, will adversely affect healing
• A diagnosed systemic disease that would affect their welfare or the overall outcome of study (i.e. Paget's disease, renal osteodystrophy)
• Patients receiving an isolated patellofemoral UKA,lateral UKA, or bi-compartmental arthroplasty
• Patients with significant medical condition preventing a well-functioning contralateral knee
• cognitively unable to complete study health-related quality of life forms

Male and non-pregnant females undergoing knee replacement who are between 21 and 80 years of age with stable health and are willing and able to have physical therapy.