## 1 Introduction  
The knee is the largest synovial fluid-filled joint in the human body [1] and exhibits different articulating surfaces. The tibofemoral joint is the weight-bearing component of the knee [1, 2], consisting of two biconvex femoral conodles that articulate on a concave medial and a convex lateral plateau of the tibia. The complex structure of the native knee joint enables flexion and extension, anterior posterior (AP) translation, abduction and adduction, as well as axial rotation movements. The degree of freedom of knee movements is mainly limited by the ligaments [3]. The dominant movements are flexion and extension, where the femoral component performs a complex rolling-sliding movement on the tibial plateau. The ratio of rolling and sliding is determined by the extent of flexion [4, 5]. At the beginning of the flexion movement, the rolling mechanism prevails. From approximately 20 to 30 degrees of flexion, rolling-sliding dominates until pure gliding occurs at the maximum degree of flexion movement. The extent of rolling-sliding is lower in the medial than in the lateral compartment [4, 5, 6]. The viscoelastic menisci ensures a consistent distribution of joint load [1]. Osteoarthritis is one of the most common diseases of the knee joint. Affected patients suffer from severe pain and reduced joint mobility, and are often treated with knee arthroplasty. This procedure is one of the most common surgical interventions in orthopedics [2]. However, one major problem of knee endoprostheses is their limited ability to replicate the natural rolling-sliding mechanism and wear propagation at bearing surfaces. Enhanced mechanical loading due to high physical activity influences the durability and functionality of knee implants [5; 7]. One of the main causes of implant failure and revision is aseptic loosening due to the release of wear debris, accompanied by an adverse biological reaction to the particles [8; 9]. Therefore, preclinical tribological and biological investigations on abrasive wear and deformation behavior are relevant for the development of suitable knee implant materials and designs. For this purpose, various wear test methods are available, which differ in complexity and testing parameters. These methods can be divided into screening and simulator studies [10]. Initial tribological screening tests mainly examine the contact surface over a short time period using simplified sample geometries and kinematics. The most commonly used test methods include pin-on-disc or cylinder-on-cylinder tests [7; 10]. To simulate wear behavior under more physiological conditions, new endoprosthetic implant materials and designs need to be tested according to international testing standards, where advanced joint-specific motion sequences and load profiles are applied. However, these tests are time-consuming and the running costs for wear data acquisition are high. Furthermore, only finalized implant prototypes are tested regarding their wear behavior at articulating surfaces, which are complex to produce [7; 10; 11]. Before such implants are produced, a test device that enables the screening of new materials with simplified geometries under biomechanical boundary conditions, adapted to the in vivo situation, should be available. Some previous studies have introduced the concept of executing combined rolling-sliding movements while applying physiological joint forces and motions. In 2004, [PERSON] et al. developed a rolling-sliding tribotester that was capable of generating realistic contact stresses [12]. The extent and frequency of rolling and sliding could be adjusted separately for each test station. Cylindrical samples of cobalt-chromium (CoCr) and polyethylene (PE) were tested in test fluid until macroscopic failure of the samples occurred [12; 13]. However, the geometric contact conditions were simplified. [PERSON] et al.