Partial replacement is generally recommended when the knee only has loss of cartilage from one area of the knee. This may be the inside (medial), the outside (lateral) or the front (patellofemoral) aspect of the knee. Partial replacements are usually preferred by most patients because they have quicker recoveries and can be done exclusively as an outpatient. Even though, the lifespan of these surgeries may be less than total knee replacement, the partial is a good bridge to the total knee. Unfortunately, only about 10-15% of patients are good candidates for partial replacement. This is best determined by pre-op exams and imaging.