Aims

This prospective randomised controlled trial was designed to evaluate the outcome of both the MRI- and CT-based patient-specific matched guides (PSG) from the same manufacturer.

Introduction. Recently, computer-aided orthopaedic surgery has enabled three dimensional (3D) preoperative planning, navigation systems and patient matched instrument, and they provide good clinical results in total knee arthroplasty. However, the preoperative planning methods and the criteria in total elbow arthroplasty (TEA) still have not sufficiently established due to the uncertainty of 3D anatomical geometry of the elbow joints. In order to clarify the 3D anatomical geometry, this study measured 3D bone models of the normal elbow joints. Additionally this study attempted to apply the 3D preoperative planning to ordinary surgery. Then the postoperative position of implant has evaluated as compared with the position in 3D preoperative planning. Methods. Three dimensional bone measurements on 4 normal cases were performed. Three dimensional bone models were constructed with CT image using Bone Viewer®(ORTHREE Co., Ltd.). TEA was performed with FINE® Total Elbow System (Nakashima Medical Co., Ltd.) for 3 rheumatoid arthritis (RA) cases (Fig. 1). Three dimensional preoperative planning was based on this bone measurement, and postoperative position of implant were evaluated. The postoperative assessments were evaluated by superimposing preoperative planning image on postoperative CT image using Bone Simulator® (ORTHREE Co., Ltd.). This study only covers humeral part. Results. The results of 3D bone measurements on 4 normal cases shows the average internal rotation angle between the flexion-extension axis and the epicondyles axis in the distal humerus was 2.2 degrees. The average valgus tilt of the distal humerus was 3.7 degrees. Postoperative position of humeral component for 3 RA cases was installed at proximal and valgus position compared to the preoperative planning. Discussion. This study indicates that ordinary two dimensional criteria and 3D anatomical one in the elbow joint may be different in several bony landmarks such as rotation, varus and valgus. Additionally these results show the differences between postoperative position of implant and preoperative position in 3D planning. More studies need to be conducted to validate postoperative evaluation and preoperative planning

Total knee arthroplasty has been shown to provide relief of pain and improved function; however studies have shown that younger active patients still note limitations in performing higher level activities such as dancing, golfing, skiing and gardening. Journey II BCS is designed to have physiological matching which more accurately reproduces the normal knee anatomy and kinematics. By providing more anatomic restoration of the articular geometry and substituting for both cruciate ligaments, Physiological Matching TKA has been shown, with in-vivo kinematic studies, to better reproduce the normal bending, rollback and rotational motions of knees. Patient matched instruments are patient specific custom designed cutting blocks. These instruments utilise pre-operative MRI and full leg x-rays to design guides that will position the knee in the desired mechanical alignment. The purpose of these instruments is to increase efficiency and accuracy, and possibly reduce cost. Efficiency occurs through the elimination of multiple steps compared to the standard operative technique. A single patient matched femoral guide is easily placed and can align the valgus angle with the mechanical axis, and determine the level of resection, rotation, size, and AP position of the implant. A single tibial instrument can determine tibial alignment, depth of resection, slope and rotation. Efficiency also results by eliminating the need for many standard instruments and trays. Implant size is determination pre-operatively so fewer implant trials are necessary. In summary, this Physiological Matching TKA surgery combines Journey II BCS with patient specific instruments to optimise kinematics, fit and efficiency in order to improve outcomes and patient satisfaction