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

Received Sep 12, 2017; Revised Feb 10, 2018; Accepted Feb 25, 2018

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1. Introduction

Medial opening wedge high tibial osteotomy (HTO) has been used to treat osteoarthritic knees with medial cartilage degeneration, especially for young and active patients [1–3]. This procedure is more favorable than lateral closing wedge HTO, which often induces complications such as compartmental syndrome, lateral muscle detachment, proximal fibula osteotomy, and limb shortening, as well as neurological complications [4–6]. Several studies have shown satisfactory outcomes with medial opening wedge HTO. Floerkemeier et al. reported favorable midterm results after using medial opening wedge HTO, even in older patients with a great deal of cartilage damage [7]. Bode et al. and Harris et al. reported over 96% and 92.4% survival rates, respectively, with excellent clinical outcomes five years after medial opening wedge HTO [8, 9]. Approximately 90% of patients returned to work or their sport within one year in Ekhtiari’s follow-up study [10]. Patients in a study by Duivenvoorden et al. had a survival rate of up to 90% ten years after medial opening wedge HTO [11].

To achieve a satisfactory outcome when performing medial opening wedge HTO, patient selection and surgical technique are important factors [12–14]. In practice, manual creation and distraction of HTO wedges are highly technique-demanding, especially for an inexperienced surgeon [7]. During the surgical procedure, potential complications, such as fractures of the lateral cortex or tibial plateau, dislocation of the lateral hinge, change in the tibial slope, and over- or undercorrection can adversely affect clinical outcomes [15]. Therefore, both accurate preoperative planning and precise intraoperative execution are necessary to obtain a satisfactory outcome with medial opening wedge HTO [16].

There are five parameters of medial opening wedge HTO, including cutting point, lateral hinge, sawing direction, sawing depth, and correction angle (Figure 1). The first is the entry position of the osteotomized wedge, which is associated with the distance $d$ between the cutting point and the medial tibial plateau (Figure 1(a)). As the second parameter, the lateral hinge is considered to be a rotation axis in the valgus correction procedure....