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Background: Flexible cavovarus deformity is prevalent and the Coleman block test is frequently used to assess the first ray plantarflexion malpositioning in the overall deformity as well as the flexibility of the hindfoot. The objective was to assess and compare the weightbearing computed tomography (WBCT) 3-dimensional (3D) changes in clinical and bone alignment in flexible cavovarus deformity patients when performing the Coleman block test when compared to normal standing position and to controls., Methods: Twenty patients (40 feet) with flexible cavovarus deformity and 20 volunteer controls (40 feet) with normal foot alignment underwent WBCT imaging of the foot and ankle. Cavovarus patients were assessed in normal orthostatic and Coleman block test positions. Foot and ankle offset (FAO), hindfoot alignment angle (HAA), talocalcaneal angle (TCA), subtalar vertical angle (SVA) and talonavicular coverage angle (TNCA) and a CT-simulated soft tissue envelope image, WBCT clinical hindfoot alignment angle (WBCT-CHAA), were evaluated by 2 readers. Measurements were compared between cavovarus nonstressed and stressed positions and to controls. P values of .05 or less were considered significant., Results: The intra- and interobserver intraclass correlation coefficient were good or excellent for all WBCT measurements. Cavovarus patients demonstrated significant correction of WBCT-CHAA (9.7 ± 0.4 degrees), FAO (2.6 ± 0.4%), and TNCA (8.8 ± 1.8 degrees) when performing the Coleman block test (all P values <.0001). However, WBCT-CHAA and FAO measurements were still residually deformed and significantly different from controls ( P values of .001 and <.0001, respectively). TNCA values corrected to values similar to healthy controls ( P  = .29). No differences were observed in cavovarus patients during Coleman block test for the coronal measures: HAA, TCA, and SVA measurements., Conclusion: In this study, we observed improvement in the overall 3D WBCT alignment (FAO), axial plane adduction deformity (TNCA), as well as CT simulated clinical hindfoot alignment (WBCT-CHAA) in flexible cavovarus deformity patients when performing a Coleman block test. However, we did not find improvement in measures of coronal alignment of the hindfoot, indicating continued varus positioning of the hindfoot in these patients., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.

Background: The cavovarus foot is a complex 3-dimensional deformity. Although a multitude of techniques are described for its surgical management, few of these are evidence based or guided by classification systems. Surgical management involves realignment of the hindfoot and soft tissue balancing, followed by forefoot balancing. Our aim was to analyze the pattern of residual forefoot deformities once the hindfoot is corrected, to guide forefoot correction., Methods: We included 20 cavovarus feet from 16 adult patients with Charcot-Marie-Tooth who underwent weightbearing CT (mean age 43.4 years, range: 22-78 years, 14 males). Patients included had flexible deformities, with no previous surgery. Using specialized software (Bonelogic 2.1, Disior) a 3-dimensional, virtual model was created. Using morphologic data captured from normal feet in patients without pathology as a guide, the talonavicular joint of the cavovarus foot was digitally reduced to a "normal" position to simulate the correction that would be achieved during surgical correction. Models of the corrected position were exported and geometrically analyzed using Blender 3.64 to identify anatomical trends., Results: We identified 4 types of cavovarus forefoot morphotypes. Type 0 was defined as a balanced forefoot (2 cases, 10%). Type 1 was defined as a forefoot where the first metatarsal was relatively plantarflexed to the rest of the foot, with no significant residual adduction after talonavicular joint correction (12 cases, 60%). Type 2 was defined as a forefoot where the second and first metatarsals were progressively plantarflexed, with no significant adduction (4 cases, 20%). Type 3 was defined as a forefoot where the metatarsals were adducted after talonavicular derotation (2 cases, 10%)., Conclusion: In this relatively small cohort, we identified 4 forefoot morphotypes in cavovarus feet that might help surgeons to recognize and anticipate the residual forefoot deformities after hindfoot correction. Different treatment strategies may be required for different morphotypes to achieve balanced correction., Level of Evidence: Level IV, retrospective case series., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.

Background: The complex deformities in cavovarus feet of Charcot-Marie-Tooth (CMT) disease are difficult to evaluate. The aim of this study was to quantify the initial standing alignment correction achieved after joint-sparing CMT cavovarus reconstruction using pre- and postoperative weightbearing computed tomography (WBCT)., Methods: Twenty-nine CMT cavovarus reconstructions were retrospectively analyzed. Three-dimensional measurements were performed using semiautomated software (Bonelogic 2.1) to investigate changes in sagittal, axial, and coronal parameters. Pre- and postoperative data were compared, along with normative data. Correlation among the preoperative measurements and the amount of correction in sagittal, axial, and coronal parameters were analyzed., 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 angle (from 14.8 to 0.1 degrees), axial talonavicular angle (TNA, from 3.6 to 19.2 degrees), and coronal hindfoot alignment (from 11.0 to -11.1 degrees) showed significant changes postoperatively ( P < .001). Hindfoot, forefoot sagittal, and forefoot axial parameters reached comparable outcomes compared with normative value ( P > .05). Regarding amount of correction, Spearman correlation demonstrated that axial Meary angle and TNA were most strongly related to improvement in sagittal Meary 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 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 cavovarus foot correction., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.

Background: The complex deformities in cavovarus feet may be difficult to assess and understand. Weightbearing computed tomography (WBCT) is increasingly used in evaluating complex deformities. However, the bone axes may be difficult to calculate in the setting of severe deformity. Computer-assisted 3D axis calculation is a novel approach that may allow for more accurate assessment of foot alignment or deformity. This study aimed to assess differences in measurements done manually on 2D slices of WBCT vs 3D computer models in normal and cavus feet., Methods: We retrospectively analyzed WBCT scans from 16 normal and 16 cavus feet in patients with Charcot-Marie-Tooth disease. Six measurements were assessed: talar-first metatarsal angle (axial plane), forefoot arch angle (coronal plane), and Meary angle, calcaneal pitch, and cuneiform and navicular to floor distances (sagittal plane). 2D measurements were performed manually and 3D measurements were performed using specialized software (Bonelogic, DISIOR). Bland-Altman plots and linear regression were used to analyze differences., Results: There were no significant biases in measured variables in normal feet. In the cavovarus group, automated assessment calculated increased sagittal plane deformity (fixed bias 7.31 degrees for Meary angle, 2.39 degrees for calcaneal pitch) and less axial plane deformity (fixed bias 10.61 degrees for axial talar-first metatarsal angle). The latter also demonstrated proportional bias indicating greater discrepancy with increasing adduction., Conclusion: Measurements were comparable in normal feet suggesting automated techniques can reliably assess the alignment of bony axes. However, automated calculations show greater sagittal and less axial deformity in cavovarus feet than measured by manual techniques. This discrepancy may relate to rotational deformity seen in cavovarus feet, which may not be easily assessed manually. 3D automated measurements may therefore play a role in better assessing and classifying the cavovarus foot, which may ultimately inform treatment algorithms., Level of Evidence: Level III, retrospective comparative study.

Background: Few authors have directly compared multiple types of lateralizing calcaneal osteotomies (LCOs) in terms of their ability to achieve deformity correction. The aim of this research was to use a digital model of a varus hindfoot to compare 4 different LCOs in terms of deformity correction and amount of tuberosity lateralization required. The authors hypothesis was that osteotomies involving a wedge resection would achieve greater correction with less lateralization., Methods: A weightbearing computed tomographic scan of a patient with a varus hindfoot deformity was used to construct a 3-dimensional digital model of the hindfoot, preserving weightbearing alignment. Four different LCOs were modeled: a standard oblique osteotomy, a Dwyer osteotomy, a modified Dwyer osteotomy involving lateralization in addition to wedge resection, and a Malerba Z-type osteotomy with wedge resection and lateralization. Incremental corrections were performed with each osteotomy type, and amount of correction was assessed with a vertical hindfoot angle and measurement of the lateral translation of the most inferior aspect of the calcaneus. Calcaneal length and osteotomy contact surface area were also measured., Results: The modified Dwyer osteotomy led to the greatest improvements in the vertical hindfoot angle and lateral translation, followed by the Malerba osteotomy. The standard and Malerba osteotomies allowed the most preservation of calcaneal length; the Malerba and Dwyer osteotomies had the greatest contact surface area., Conclusion: LCOs that involve wedge resection as well as lateralization were able to achieve the greatest correction of hindfoot varus., Clinical Relevance: For the surgical treatment of cavovarus foot deformities, osteotomies with wedge resection in addition to lateralization enable more powerful correction.