The Effect of Medial Displacement Calcaneal Osteotomy on Tarsal Tunnel Volume

CATEGORY: Hindfoot INTRODUCTION/PURPOSE: Tarsal tunnel volume is affected by position of the foot and the alignment of the ankle. Although medial displacement calcaneal osteotomy (MDCO) significantly alters the alignment of the hindfoot, the change of tarsal tunnel volume after this procedure has not yet been well documented. Therefore, authors investigated the volumetric change of tarsal tunnel after MDCO using Computed Tomography (CT) scan. METHODS: This retrospective study involved 101 feet of 91 patients who underwent a MDCO at our institution from March 2016 to December 2018. We compared the tarsal tunnel volume from the preoperative and postoperative CT scan images under following protocols. On a sagittal scout image, the oblique axial plane was drawn parallel to the long axis of the calcaneus using talonavicular joint as a landmark. Serial oblique axial images were displayed using PACS (PathSpeed, GE Healthcare, Chicago, IL, USA) with both the soft tissue and the bone window settings. The volume of tarsal tunnel was evaluated from just distal to the tip of medial malleolus anterior colliculus to distance of 3 cm distal using 10 consecutive images by drawing the border of tarsal tunnel. The volume was calculated by adding 10 cross-sectional areas and then multiplying by 3 mm corresponding to slice thickness. RESULTS: The mean preoperative and postoperative tarsal tunnel volume were 12229 mm3 (SD, 1842 mm3) and 12762 mm3 (SD, 1803 mm3), respectively. There was 4.6% (SD, 3.4%) of volume increase after MDCO (p <0.001). Results indicated high inter- and intraobserver reliability coefficients (r = 0.97, r = 0.98, respectively). CONCLUSION: MDCO increased the volume of tarsal tunnel. This finding might support clinicians performing MDCO as a conjunctive surgical option in treating patients with tarsal tunnel syndrome.