Bilateral Graph

http://www.healio.com/orthopedics/hip/journals/ortho/%7B0b0108a2-3a34-4788-825b-e6533f73c62f%7D/one-stage-bilateral-total-joint-arthroplasty-a-prospective-comparative-study-of-total-hip-and-total-knee-replacement

Bilateral graphs are meant to represent two different sets of data in one map in a way that is easy to understand. This is a graph representing patients with joint problems. It shows both the number of patients and their general age group.