The purpose of this study was to determine the results of modular unlinked bicompartmental knee arthroplasty (BiKA) for medial (or lateral) and patellofemoral arthritis. Twenty-nine modular BiKAs were followed prospectively, for a mean of 31 months (range, 24–46 months). Outcome measures included Knee Society Knee and Function Scores, KOOS, SF-12, and WOMAC, as well as radiographic assessments and implant survivorship. Two tail paired Student’s t test was used to determine statistical differences between preoperative and postoperative scores. Mean range of motion (ROM) improved from 122° to 133° (P < 0.001). There was a statistically significant improvement across all functional scores. One patient underwent conversion to total knee arthroplasty at 3 years for knee instability. There were no cases of patellar instability, implant loosening or wear, or progressive arthritis.