A new ISO-based quality concept for evaluating accuracy in CAOS surgery

Since 1990s, the complexity and frequency of orthopaedic interventions involving bone cutting and assembly have led to extensive development of computer assistance technologies to improve clinical outcomes through increased accuracy and reproducibility. Navigation systems, robots and patient-specific instruments are undergoing clinical trials or are already in use for knee and hip arthroplasty, high tibial open-wedge osteotomy, periacetabular osteotomy, tumor resection, craniotomy, and maxillofacial osteotomy [1-9]. In 2004, the methodology for evaluating the quality in orthopaedic surgery was subject to a substantial evolutionary step with the International Society for Computer Assisted Orthopaedic Surgery (CAOS-int) in conjunction with the American Society for Testing and Materials (ASTM) [10]. These societies undertook the creation of a new ASTM standard for assessing and comparing the performances of CAOS systems. This standard was published in 2010 as F2554-10 [11] and used the definition of accuracy and precision parameters provided by the ASTM standard E177-08 [12]. The standard F2554-10 was recently used for assessing the positioning accuracy of surgical assistance systems [13,14]. However, this attempt at formulating an objective methodology for evaluating the quality in orthopaedic surgery did not account for the standards from the International Organization for Standardization (ISO) that are commonly used in mechanical engineering since years [15], especially the ISO1101 standard that is applied since the 1980s for evaluating mechanical cutting and assembly processes [16]. Considering bone as a specific mechanical material, the ISO1101 standard could be used to define the dimensional and geometrical specifications of the desired bone cutting and assemblies and evaluate the quality of the performed cutting and assemblies. Implicitly, this ISO-based methodological idea is already known among the scientific community. In 2009, Pearle et al. [17] and Rivkin et al. [18] have proposed the concept of orthopaedic quantitative and objective surgery, by emphasizing the needs for quantitative and objective data for evaluating the added value of assistance technologies. However, despite its obvious conformity with the ISO standards methodology, no research work undertook to implement this quantitative and objective surgery concept by specifically using the ISO1101 standard and guidelines. In this context, we propose a new quality concept, called ISO-CAOS, which aims at formulating and validating the first ISO-based evaluation of the quality of bone cutting and assembly in CAOS surgery. The specific objectives we aim to achieve are (1) to develop new quantitative models of bone cutting and assembly that comply with the standard ISO1101, and (2) to implement new objective methods and techniques for measuring the quality in CAOS surgery that comply with the common ISO guidelines.