Outpatient services are one of the most congested hospital divisions because they combine consultation, care and follow-up activities. These services are often confronted with several challenges such as inadequate resources and personnel management, the highly complex flow of patient information, and especially the long travel-time of patients inside the service. Indeed, the flow of patients into these services has become increasingly intensive, resulting in long waiting time for patients and a heavy burden on the service staff. In this paper, we address the problem of patient cycle time in the outpatient department of orthopedic surgery at Habib Bourguiba hospital in Sfax. The objective of this study is to minimize the average waiting time of patients with the minimum cost of services. An optimization approach based on simulation is proposed. Three mathematical models that describe the objectives related to waiting time and service cost are formulated and then implemented using the OptQuest tool of Arena software. The experimental results showed a great improvement of the service performance.