In this paper, we propose a system to reconstruct the 3D surface of a synthetic knee using an endoscope and optical fiber under the water. It is able to scan the knee joint’s profile even in narrow operated space and provide surgeons with 3D surface reconstruction in real time, which is very small in size, for the application of Mosaicplasty surgery from the surgical standpoint. Several sets of experiments were carried out to assess the proposed method, and it turned out that the accuracy was 0.56 mm with a standard deviation (STD) of 0.261 for plane reconstruction and 2.47 mm (5.04% difference) for surface reconstruction.