Effect of diastasis shape and size during calcaneal lengthening osteotomy on correction outcomes in different forms of flatfoot: an experimental cadaveric study

BACKGROUND: Despite the high prevalence of flatfoot in children, the development of surgical techniques for its treatment has significantly outpaced their biomechanical justification. Cadaveric studies in traumatology and orthopedics have traditionally served as a primary method for gaining deeper insight into the biomechanics of deformities. Preoperative planning of osteotomy gap parameters remains a relevant issue when correcting various clinical forms of pediatric flatfoot.

AIM: This study aimed to evaluate the effect of the shape and size of the osteotomy gap, specifically its angular and linear parameters, on the correction of different clinical forms of flatfoot during calcaneal lengthening osteotomy under controlled conditions (in a cadaveric study).

METHODS: An experimental cadaveric study was conducted using a vertical load simulation device with radiographic control. The study was performed on 8 anatomical specimens of the lower leg and foot. The study consisted of two stages. During the first stage, anatomical specimens were prepared for placement in the vertical load simulation device, followed by radiographic examination under unloaded conditions and a simulated load of 750 N. During the second stage, a cadaveric flatfoot model was created with the possibility of simulating two clinical forms (abducted planovalgus deformity and flatfoot deformity), followed by calcaneal osteotomy and sequential implantation of specially designed implants of various shapes under radiographic control. Radiographic parameters were assessed at each stage of the study, including the Kite angle, talonavicular coverage angle (according to V. Mosca), cuboid abduction angle, longitudinal arch angle, calcaneal inclination angle, and Meary angle.

RESULTS: At the first stage of the study with anatomical specimens, reproducible cadaveric flatfoot models were successfully obtained using the proposed method, allowing the simulation of two clinical forms: abducted planovalgus deformity and flatfoot deformity. At the second stage, calcaneal lengthening osteotomy performed with different implant shapes demonstrated distinct patterns of change in radiographic parameters depending on the clinical form of flatfoot, which reflects differences in correction biomechanics.

CONCLUSION: The study demonstrated that the shape of the osteotomy gap, when selected in accordance with the clinical form of flatfoot, may play a key role in restoring the proper foot configuration.