On Nov. 2, 2009, plaintiff Helen Yoon, 67, a ceramics painter, was driving her 2001 Toyota Camry east on the Artesia Freeway (also known as State Route 91), near the Long Beach Freeway (also known as Interstate 710), in Los Angeles, when she was involved in a four-vehicle chain collision. Her car was rear-ended by a 2009 Chevy Malibu operated by Kristina Prior, who was in the course and scope of her employment with Mercury Insurance Services, LLC. The impact caused Yoon to rear-end a non-party vehicle that was stopped in front of her and the force of that impact subsequently caused the non-party vehicle to rear-end another non-party vehicle that was stopped in front of it. Yoon claimed to her left shoulder, left elbow, lower back, and neck. The vehicles of both Yoon and Prior sustained frame damage. However, no paramedics or police were at the scene. The parties ultimately traded information after the accident. Yoon sued Prior; Prior’s employer, Mercury Insurance Services, LLC; and the owner of Prior’s vehicle, Mercury Casualty Co. In addition, Mercury Insurance Co. was later added to the case. Yoon alleged that Prior was negligent in the operation of the Chevy Malibu and that the Mercury entities were vicariously liable for Prior’s actions. Prior ultimately admitted liability for the accident., Yoon claimed she suffered a torn rotator cuff in her left shoulder, and bulging cervical and lumbar discs. She also claimed she suffered epicondylitis, also known as tennis elbow, of her left elbow. Yoon subsequently saw her treating orthopedic surgeon, who recommended surgeries for her left shoulder, left elbow, and neck. On Dec. 8, 2011, Yoon underwent an arthroscopy of her left shoulder to repair the rotator cuff. She then underwent physical therapy three times after the surgery. However, Yoon claimed the surgery was unsuccessful, so in March 2014, she underwent a second surgery, which included an open reduction of the left shoulder. She then underwent physical therapy treatments for her elbow, neck and back until just before the trial. Yoon claimed that she still has residual symptoms for all of her . She claimed that as a result, she will need further shoulder treatment. Thus, she claimed her damages were in excess of $110,000. Defense disputed the nature and extent of Yoon’s claimed , noting that Yoon did not seek emergency care immediately after the accident. The defense’s orthopedic surgery expert opined that the subject motor vehicle accident contributed to Yoon’s shoulder injury and that the first surgery was medically reasonable and necessary. However, he opined that although the second shoulder surgery was medically reasonable and necessary, it was not related to the subject accident. Thus, defense counsel argued that Yoon’s torn rotator cuff was pre-existing and/or sustained after to the subject collision.