The purpose of this study is to collect information on complications and survivorship of patients implanted with the Oxford™ Meniscal Unicompartmental Knee System at multiple sites in the United States.

Study Objective

To provide a prospective 2-year post-operative evaluation of complications and 9-year long-term survivorship analysis of patients implanted with the Oxford™ Meniscal Unicompartmental Knee System at multiple sites in the United States.

Study Design

The study is designed as a prospective, multi-center, non-randomized post approval study. There are two phases to this study:

1. A complications study where patients will be followed for at least 2 years to record all complications that may occur, and
2. A survival study that will record at yearly intervals out to 9 years whether or not the device is still in place or if it has been removed for any reason.

Phase 1 requires clinical follow-up (0-2 year) and patients will be evaluated at pre-defined intervals up to 2 years post-operative. Information gathered in phase 1 includes all adverse events and survival data.

Phase 2 (3-9 year) only gathers survival data through patient directed mailing and/or phone call.

Inclusion Criteria:

• Patients with one of the following diagnoses in the medial compartment of the knee: Osteoarthritis, Avascular Necrosis

Exclusion Criteria:

• Patients with Rheumatoid arthritis or other forms of inflammatory joint disease
• Patients with infection, sepsis, and osteomyelitis
• Patients with Osteoporosis, Paget's Disease, Charcot's disease, Osteomalacia, and Severe Osteoporosis

A Multi-center study conducted in the United States of patients who meet the FDA approved indications for use. The Oxford Meniscal Unicompartmental Knee System is intended for use in individuals with osteoarthritis or avascular necrosis limited to the medial compartment of the knee and is intended to be implanted with bone cement.