Clinical application of three-dimensional printing in the treatment of knee varus with high tibial os-teotomy

Abstract

Objective To evaluate the clinical application of a three-dimensional (3D) printing personalized guide for medial open wedge high tibial osteotomy(MOWHTO) in the treatment of knee varus osteoarthritis. Methods A retrospective study was conducted of the 16 patients with knee varus os-teoarthritis who had been treated at Department of Orthopaedics, Zhengzhou Central Hospital of Zhengzhou University from January 2016 to January 2017. They were 6 men and 10 women, aged from 49 to 65 years (mean, 55.8 years). Bilateral knees were involved in 2 cases and a unilateral knee was involved in 14 cases. Their disease duration ranged from one to 12 years (mean, 5.3 years). A personalized guide for MOWHTO was designed and manufactured by 3D printing for every patient preoperatively. All the patients underwent knee arthroscopy before osteotomy which was assisted by the personalized guide. The femorotibial angle (FTA), medial proximal tibial angle (MPTA), weight bearing line (WBL), posterior tibial slope (PTSA) and the patellofemoral height Insall-Salvati index (IS index) were measured on their X-ray radiographs preoperatively and 6 months postoperatively. The Hospital for Special Surgery (HSS) score and visual analogue scale (VAS) were used to evaluate the outcomes at the final follow-ups. Results All surgeries were successful. The 16 patients were followed up for 6 to 12 months (mean, 9.1 months). The FTA, MPTA, WBL and IS index at postoperative 6 months were significantly improved than the preoperative values (P<0.05). There was no significant difference between postoperative PTSA and preoperative PTSA (P=0.990). The mean VAS scores for the 16 patients at the final follow-ups were 0.8±0.7 points, significantly better than the preoperative ones (4.2±0.9 points) (P<0.05); their mean postoperative HSS scores (89.3±6.7 points) were also significantly improved than the preoperative ones (61.9±10.5 points) (P<0.05). According to the HSS scores at the final follow-ups, the surgical outcomes were excellent in 14 knees, good in 3 and fair in one. Conclusion A 3D printed osteotomy guide can be used to perform precise osteotomy in MOWHTO for knee varus osteoarthritis, leading to effective correction of the alignment of the lower limb and good short-term surgical outcomes. Key words: Knee joint; Osteoarthritis; Abnormalities; Osteotomy; 3D printing technology