Biomechanical aspects of spinal sagittal balance in achondroplasia patients during Ilizarov limb lengthening

Abstract

To review specific features of spinal sagittal balance in achondroplasia patients at stages of lower limb lengthening using the Ilizarov method. Material and Methods. Cross-sectional clinical and radiological study was performed in 29 achondroplasia patients prior to lower limb lengthening and at lengthening stages using the Ilizarov method. Parameters of sagittal balance of the spine and pelvis were evaluated radiologically. Clinical evaluation included examination, and assessment of neurological status and pain level. Results. Clinical manifestations of sagittal imbalance included hypokyphosis of the thoracic spine in 44.8 % of cases and increased lumbar lordosis in 55.2 %. No neurological disorders were diagnosed in patients. Pain scores 2 to 4 were observed in 17.2 % ofcases. After staged lower limb lengthening by 19.8 ± 3.3 cm, it was revealed that the values of the thoracic kyphosis, lumbar lordosis and the angle of the sacrum tilt improved and approached those of healthy peers. Vertical sagittal alignment measurements correlated with those of thoracic kyphosis. Thoracic kyphosis showed a correlation with lumbar lordosis. Pelvic indices had a moderate correlation with lumbar lordosis. Conclusion. Biomechanically substantiated transosseous compression-distraction osteosynthesis by Ilizarov technique used for lower limb lengthening in achondroplasia patients improves spinal sagittal balance parameters.