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 classify the pattern of residual forefoot deformities once the hindfoot is corrected, to guide forefoot correction. Methods. We included 20 cavovarus feet from adult patients with Charcot-Marie-Tooth who underwent weightbearing CT (mean age 43.4 years, 14 males). Patients included had flexible deformities, with no previous surgery. Previous work established majority of rotational deformity in cavovarus feet occurs at the talonavicular joint, which is often reduced during surgery. Using specialised software (Bonelogic 2.1, Disior) a 3-dimensional, virtual model was created. Using data from normal feet as a guide, the talonavicular joint of the cavovarus feet was digitally reduced to a ‘normal’ position. Models of the corrected position were exported and geometrically analysed using Blender 3.6 to identify anatomical trends. Results. We identified 3 types of cavovarus forefoot morphotypes. Type 1 was seen in 13 cases (65%) and was defined as a foot where only the first metatarsal was relatively plantarflexed to the rest of the foot, with no significant residual adduction after talonavicular correction. Type 2 was seen in 4 cases (20%) and was defined as a foot where the second and first metatarsals were progressively plantarflexed, with no significant adduction. Type 3 was seen in 3 cases (15%) and was defined as a foot where the metatarsals were still adducted after talonavicular de-rotation. Conclusion. We classify 3 forefoot morphotypes in cavovarus feet. It is important to recognise and anticipate the residual forefoot deformities after hindfoot correction as different treatment strategies may be required for different morphotypes to achieve balanced correction

Introduction:. The cavovarus foot is a complex deformity caused by muscle imbalance, soft-tissue contracture and secondary bony abnormality. It is a combination of hindfoot, midfoot and forefoot deformity and the decision making process for surgical management can be difficult. The process of deciding which combination of procedures is required is often poorly understood. We present an algorithm to assist with this decision making. Methods:. We have analysed a single surgeon's experience of cavovarus foot correction, from a consecutive series of 50 patients over 5 years, to develop an algorithm to guide operative decision making. Cases included cavovarus deformity secondary to cerebral palsy, Friedreich's ataxia, Charcot Marie Tooth disease, post-traumatic contracture, post-cerebrovascular accident, iatrogenic post-surgery and physiological cavus. We have taken a systematic approach to each component of the deformity in order to generate the algorithm. Results:. To assist in rationalising the traditional ‘a-la-carte’ approach, our algorithm describes what we believe are the indications for a variety of surgical interventions, including soft tissue contracture release, osteotomies of the hindfoot, midfoot and forefoot, tendon transfer and soft tissue balancing, and arthrodesis. We detail the decision making process for each surgical option and give the reasons for each decision. We have also reviewed the available literature on this topic, to produce an evidence-based and useable tool for surgical planning. Conclusion:. The surgical decision making process in the management of the cavovarus foot is complex. We believe that this algorithm, based on extensive personal experience and up-to-date published evidence, provides a clear and proven framework on which surgical decision making can be guided and justified