Pain in both the lumbar and knee joints is usually caused by two parts: 1. Pain in both the lumbar and knee joints may occur due to disorders in both the lumbar and knee joints, such as lumbar muscle strain, lumbar myofibrosis, third transverse process syndrome, and lumbar disc herniation in the lumbar region, and patellar chondromalacia, joint effusion, and osteoarthritis in the knee region. 2. caused by a herniated lumbar disc, and symptoms of pain within the distribution of the nerves associated with the lower extremities.