Semi-Automatic 3D Assessment of Zadek Osteotomy Effects

Abstract

Category: Hindfoot; Sports Introduction/Purpose: Zadek's procedure is a surgical option to treat insertional Achilles tendinopathy(IAT). This procedure consists of a closing wedge osteotomy of the calcaneus with biomechanical consequences. Great modifications in the hindfoot alignment can result in poor functional outcomes for athletes. Additionally, some authors stated that Zadek osteotomy is a good choice for patients with IAT associated with cavovarus foot. This study aims to analyze the hindfoot alignment and the parameters related to Haglund's syndrome after Zadek's osteotomy using a virtual surgical simulation by specific software. The authors hypothesize that the Zadek is an effective technique to decompress the Achilles tendon against the Haglund deformity without major modifications in the alignment. Methods: A total of 20 WBCT scans of patients with IAT were included. The WBCT images were run through the Foot & Ankle module of Disior's BonelogicTM software, creating a 3D virtual model. With this 3D model built into this software, 20 virtual Zadeck osteotomies standardized with a 10 mm resection wedge were performed using the virtual osteotomy module of Bonelogic®. The Calcaneal Inclination angle (sagittal view)7; Talocalcaneal angle (sagittal view)8; Talocalcaneal angle (axial view)8; Saltzman angle (45 degrees view)9; Saltzman angle (20 degrees view)9; Hindfoot moment arm angle;10 Hindfoot angle10; Fowler Philips angle11 and the calcaneal length7 were measured before and after the virtual osteotomy. These results were compared and statistically analyzed. Results: A virtual Zadek osteotomy was realized in 20 WBCT from patients with an insertional Achilles tendinopathy. Most of the patients were female, and the mean age was 55 years. There were significant statistical differences in the average of the calcaneal length (79 mm to 73 mm), Fowler Philips angle (57º to 43º), calcaneal pitch ( 24º to 20º ), sagittal talocalcaneal angle (55º to 47º ), and the hindfoot moment arm angle (20 º to 21,8º). The axial talocalcaneal angle, Saltzman view 45 º and 20 º, and Hindfoot moment arm showed subtle modifications. Conclusion: The virtual analysis of Zadek's osteotomy decreased the Fowler Philips angle, shortened the calcaneus, and modified the alignment in the sagittal view. It suggests that Zadek's procedure reduces the bone impingement with Achilles and the Achilles push. The effect of this osteotomy in Hindfoot Alignment was subtle, modifying only the sagittal plane.