Abstract: At 11:00 a.m. on June 12, 2017, an employee was manually opening and closing a horizontal gate to allow passage of vehicles because the power to the gate was out. As the employee pushed the gate closed, the employee stepped off the curb awkwardly and twisted the left knee. The employee did not fall to the ground. The employee thought is was a minor incident and kept working for the remainder of the shift. The employee returned to work on June 13. At about 09:30 a.m. the employee felt soreness in the left knee which became swollen by the end of the shift. The employee did not work on June 14. During the next 3 days, pain in the employee's knee was steady. On June 18, the pain became worse. The employee went to the hospital on June 19, 2017 and was hospitalized till June 24, 2017. There was infection in the employee's left knee. Surgery was performed on the employee's knee.