Peyronie's disease causes the penis to curve during erection due to scar tissue forming in the penis. The curvature may worsen initially but will typically stabilize within 3-12 months. Risk factors include genetic connective tissue disorders, family history, diabetes, smoking, and past pelvic trauma. Diagnosis involves physical exam and sometimes ultrasound. Treatment depends on the disease stage - early on options include traction therapy to prevent worsening, while later options include injections, surgery, or watchful waiting once the curvature is stable.