Summary

Satisfactory clinical and alignment accuracy outcomes of an innovative 3D-printed customized system for valgus high tibial osteotomy at one-year follow-up. Promising results from the first prospective in vivo experience.

Abstract

Background

High tibial osteotomy represents a well established treatment for patients with medial OA and varus knee. Personalized surgical technologies offer the potential for simplified surgical techniques and increased accuracy.

Objective

To perform the first-in-man trial about a new customized cutting guide and fixation plate system for valgus HTO in patients with medial OA and varus knee.

Methods

A single-arm prospective interventional trial was performed. Twenty-five patients with medial compartment OA and varus knee malalignment who underwent surgical HTO with a patient-specific system were prospectively evaluated at pre-operative, one month, three months, six months, and one-year follow-up. Imaging analysis included: a weight-bearing long leg radiograph and CT scan (Carestream, Rochester, NY, USA), which were used for digital planning and creation of the personalized surgical guide and plate, as well as anteroposterior and lateral radiographs of the knee. Clinical assessment was performed using the KOOS score and KOOS sub-scales, KSS score, and VAS pain scale.

Results

At six months postoperatively, the mean HKA was 182.6° (sd 2.9°, range 178.1° to 182.6°), and mean ML was 39.6% (sd 11.0%, range 16.8% to 55.9%). The overall mean difference between planned and achieved correction in terms of HKA was 2.1° (sd 2.0°, range -1.1° to 5.8°) and in terms of ML was -9.7% (sd 8.4%, range -26.9 to 3.8%). Total KOOS had a significant (p<0.001) increase from a pre-operative value of 56.3 (95%CI 50.4 to 62.0) to 72.9 (95%CI 69.7 to 76.1) at three months postoperatively, with a further significant (p<0.001) increase at six months postoperatively to 82.1 (95%CI 78.6 to 85.5) which was maintained at 12 months. KSS-O increased significantly (p<0.001) from a pre-operative value of 58.6 (95%CI 53.1 to 64.1) to 95.8 (95%CI 92.5 to 99.0) at 12 months post-operative. KSS-F significantly (p<0.001) decreased from the pre-operative value of 82.2 (95%CI 77.8 to 86.6) to 98.6 (95%CI 96.9 to 100.3) at one-year follow-up. Both VAS pain scores (VASrest, VASact) showed a significant (p<0.001) variation with follow-up time.

Conclusion

The personalized 3D printed HTO system used in the current study showed correction accuracy levels similar to navigation. The clinical outcomes are excellent, with a very rapid improvement, especially in terms of pain and return to function.