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      Clinical Experience Using a 3D-Printed Patient-Specific Instrument for Medial Opening Wedge High Tibial Osteotomy


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          High tibial osteotomy (HTO) has been adopted as an effective surgery for medial degeneration of the osteoarthritis (OA) knee. However, satisfactory outcomes necessitate the precise creation and distraction of osteotomized wedges and the use of intraoperative X-ray images to continually monitor the wedge-related manipulation. Thus HTO is highly technique-demanding and has a high radiation exposure. We report a patient-specific instrument (PSI) guide for the precise creation and distraction of HTO wedge.


          This study first parameterized five HTO procedures to serve as a design rationale for an innovative PSI guide. Preoperative X-ray and computed tomography- (CT-) scanning images were used to design and fabricate PSI guides for clinical use. The weight-bearing line (WBL) of the ten patients was shifted to the Fujisawa's point and instrumented using the TomoFix system. The radiological results of the PSI-guided HTO surgery were evaluated by the WBL percentage and tibial slope.


          All patients consistently showed an increased range of motion and a decrease in pain and discomfort at about three-month follow-up. This study demonstrates the satisfactory accuracy of the WBL adjustment and tibial slope maintenance after HTO with PSI guide. For all patients, the average pre- and postoperative WBL are, respectively, 14.2% and 60.2%, while the tibial slopes are 9.9 and 10.1 degrees. The standard deviations are 2.78 and 0.36, respectively, in postoperative WBL and tibial slope. The relative errors of the pre- and postoperative WBL percentage and tibial slope averaged 4.9% and 4.1%, respectively.


          Instead of using navigator systems, this study integrated 2D and 3D preoperative planning to create a PSI guide that could most likely render the outcomes close to the planning. The PSI guide is a precise procedure that is time-saving, radiation-reducing, and relatively easy to use. Precise osteotomy and good short-term results were achieved with the PSI guide.

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          Most cited references 36

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          Outcome after high tibial open-wedge osteotomy: a retrospective evaluation of 533 patients.

          Open-wedge valgus high tibial osteotomy is a well-established procedure in the management of medial osteoarthritis of the knee. In recent years, improved osteotomy and fixation methods have led to an increased use of this technique. The aim of this study was to identify predictive parameters for the clinical outcome after valgus high tibial osteotomy.
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            Biomechanics of high tibial osteotomy.

             Andrew Amis (2012)
            This paper is a review of the biomechanical principles that support limb realignment surgery via osteotomy around the knee, principally high (proximal) tibial osteotomy. The basic biomechanical principles have been described, and the related literature examined for evidence to support the recommendations made. The forces on the knee when walking are shown to lead to most of the load acting through the medial compartment, the most frequent site of degeneration of the knee, due to the adduction moment that acts during the weight-acceptance phase. Realignment of the limb to move the mechanical axis to a desired point within the knee is described, and the resulting joint contact pressures in the medial and lateral compartments are shown to be higher in the less-congruent lateral articulation when the load passes through the centre of the knee. At the same time, there can be changes of the posterior slope of the tibial plateau, and a slope of ten degrees can induce a shearing force, which stretches the ACL, of 0.5 body weight when the knee force is 3 times body weight. The options regarding tibial or femoral or even double osteotomies are discussed in relation to medial-lateral slope of the joint line. Secondary effects such as alteration of collateral ligament tension or of the height of the patella are described. Critical review of the publications supporting osteotomy surgery suggests that many of the accepted 'rules' have little scientific evidence to show that they represent the best practise for long-term preservation of the joint.
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              Opening wedge tibial osteotomy: the 3-triangle method to correct axial alignment and tibial slope.

              Although a change in tibial slope may occur during a medial opening wedge osteotomy, calculations have not been defined to address this problem. The authors investigated geometric factors important to correct axial alignment and tibial slope during osteotomy. To calculate, through 3-dimensional analysis of the proximal tibia, how the angle of the opening wedge along the anteromedial tibial cortex influences the tibial slope (sagittal plane) and valgus correction (coronal plane) during osteotomy, and to analyze the different radiographic methods reported in the literature to measure medial and lateral tibial slope. The authors postulated that differences in reported normal values of tibial slope in the sagittal plane were technique dependent. Descriptive laboratory study. The proximal anteromedial tibial cortex obliquity on magnetic resonance imaging was measured in 35 knees. Serial computed tomography images of the proximal tibia were digitized, allowing a series of virtual opening wedge osteotomies to be performed. Algebraic calculations defined the effect of an opening wedge osteotomy on the anteromedial tibial cortex opening wedge angle, sagittal tibial slope angle, and coronal valgus alignment. The anteromedial tibial cortex oblique angle at the medial osteotomy site was 45 degrees +/- 6 degrees and determined, along with the degrees of valgus correction, the degrees of the opening wedge angle in the oblique plane. The anterior osteotomy gap at the tibial tubercle was generally one half of the posteromedial gap to maintain the normal sagittal tibial slope. Every millimeter of gap error at the tibial tubercle resulted in approximately 2 degrees of change in the tibial slope. The width of the buttress plate along the anteromedial tibial cortex was 2 to 3 mm less than the computed coronal valgus posteromedial osteotomy gap to achieve tibiofemoral valgus correction. A series of measurements preoperatively and intraoperatively are required to obtain the desired correction of tibial slope and valgus alignment.

                Author and article information

                Biomed Res Int
                Biomed Res Int
                BioMed Research International
                8 May 2018
                : 2018
                1Department of Orthopedic & Traumatology, Taipei Veterans General Hospital, Taipei, Taiwan
                2Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
                3Department of Orthopedics, School of Medicine, National Yang-Ming University, Taipei, Taiwan
                4Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan
                5Institute of Anatomy and Cell Biology, National Yang-Ming University, Taipei, Taiwan
                6Department of Orthopedic Surgery, Taipei City Hospital and Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
                7Adult Orthopedic Department, Beijing JST Hospital, Beijing, China
                Author notes

                Academic Editor: Despina Deligianni

                Copyright © 2018 Jesse Chieh-Szu Yang et al.

                This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                Research Article


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