3D Semi-Automated Analysis of Joint Sparing Charcot-Marie-Tooth Cavovarus Reconstruction Using Preoperative and Postoperative Weightbearing Computed Tomography

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Charcot-Marie-Tooth (CMT) disease is the most common cause of cavus foot. The complex deformities in cavovarus feet of CMT disease are difficult to evaluate. The bone axes of CMT may be difficult to calculate by conventional weightbearing computed tomography (WBCT). For this reason, 3D automated measurements have been used to assess complex anatomy. The aim of this study was to quantitatively assess deformity correction following joint sparing CMT cavovarus reconstruction surgery. This is the first study investigating preoperative and postoperative WBCT findings in CMT feet using semi-automated 3D measurements. Methods: The study was approved by our institutional review board and informed consent was obtained from all patients. Joint sparing CMT surgery was performed with multiple soft tissue releases and bony procedures. Among the 170 cases from May 2021 to May 2023, twenty-nine CMT patients who had both pre- and postoperative WBCTs were retrospectively analyzed. 3D measurements of WBCT were performed using semi-automated software (Bonelogic 2.1, Disior) to investigate changes in sagittal, axial, and coronal parameters. Pre- and postoperative data was compared using a Wilcoxon signed-ranks test and these data were also compared with normative data using a Welch's t-test. Correlation among these sagittal, axial, and coronal parameters were analyzed using Spearman’s rank correlation coefficient test. Results: The sagittal, axial, and coronal malalignment of the hindfoot, and the sagittal and axial malalignment of the forefoot was significantly improved after corrective surgery (P < .05). Sagittal Meary’s angle (from 14.8 degrees to 0.1 degrees), axial talonavicular angle (TNA, from 3.6 degrees to 19.2 degrees), and coronal hindfoot alignment (from 11.0 degrees to -11.1 degrees) showed significant changes postoperatively (P < .001). Hindfoot, forefoot sagittal and forefoot axial parameters reached comparable outcomes compared to normative value (P > .05). Regarding amount of correction, Spearman’s correlation demonstrated that axial Meary’s angle and TNA were most strongly related to improvement in sagittal Meary’s angle and coronal hindfoot alignment. Conclusion: Preoperative and postoperative WBCT measurements demonstrated that joint sparing CMT cavovarus reconstruction significantly improved sagittal, axial, and coronal deformities of CMT, and sagittal Meary’s angle was restored toward normative values. Apparent axial plane correction, the majority of which occurred at the talonavicular joint, had the strongest correlation with deformity correction in multiple planes. This suggests that soft tissue releases and correction of the talonavicular joint may be a key component of a CMT cavovarus foot correction. Figure. (A) CMT surgery with soft tissue releases and bony procedures, (B) Pre- and postoperative radiographic results, and gross photos of the operated right foot of a 17-year-old male patient.