Effects of medial displacement calcaneal osteotomy and lateral column lengthening osteotomy variations on hindfoot alignment: A three-dimensional anatomical model study

Purpose: Progressive Collapsing Foot Deformity (PCFD) involves medial arch collapse, forefoot abduction, decreased talonavicular coverage, and hindfoot valgus. This study evaluates the effects of medializing calcaneal osteotomy (MDCO) and lateral column lengthening osteotomy (LCLO) on foot alignment via virtual surgery, aiming to establish a preoperative treatment algorithm and develop a 3D solid educational model for resident training. Materials and Methods: 3D virtual models of weight-bearing CT scans from six stage I PCFD patients were used to simulate 5mm, 10mm, 15mm MDCO and LCLO, creating 36 postoperative models. Postoperative changes were assessed by measuring the AP talocalcaneal angle, hindfoot angle, hindfoot moment arm, AP talus-first metatarsal angle, and talonavicular coverage. In the solid training model talonavicular coverage change with LCLO was evaluated. Results: In virtual surgery, 5, 10, and 15 mm LCLO produced AP talus–first metatarsal angle changes of 4.1°±0.9, 9.3°±1.3, and 13.9°±2.0, respectively, with talonavicular coverage changes of -4.6°±0.9, -10.7°±2.0, and -14.5°±1.0. Corresponding MDCO changes in the hindfoot moment arm were 5.3mm±0.7, 10.0mm±1.3, and 15.1mm±1.2, hindfoot angle changes were 4.49°±0.62, 9.19°±1.64, and 13.74°±2.34, and AP talocalcaneal angle changes were 3.5°±0.3, 7.3°±1.6, and 10.9°±0.9. LCLO-related talonavicular coverage changes were consistent between virtual and solid models. Conclusion: A preoperative planning algorithm has been developed to formulate the amount of MDCO and LCLO to be applied based on the degree of deformity for the treatment of PCFD. Solid models, which yield similar results to virtual surgery, can make significant contributions to resident training.