Crankshaft Phenomenon in Adolescent Idiopathic Scoliosis

Abstract

Crankshaft Phenomenon refers to the loss of three-dimensional correction of the scoliotic curve which occurs after the back spine fusion is done to children who have not completely reached the skeletal maturity. Patients with infantile and juvenile idiopathic scoliosis are at the highest risk; however, this phenomenon also occurs in adolescents who are immature at the time of surgery. The aim of this study was to determine the relationship between the age of operated patients and the possible postoperative progression of scoliotic incurvation (The Crankshaft’s Phenomenon) after surgical correction of adolescent idiopathic scoliosis. The retrospective-prospective study was performed among 48 patients with adolescent idiopathic scoliosis, randomised selected, with both sexes included. All analyzed patients underwent a surgical correction of scoliosis through rear access, using the Isola's or the SSE (Spine System Evolution) implants. Correlation between presurgical and postsurgical values (at the end of the physiological growth) ​​of spine scoliosis part Cobb's Angle is investigated. The increase of the scoliotic part curvature (an average of 16.22%) in patients operated in the period of the intensive growth of the spine can be expected due to the ratio of the measured quantities of Cobb 's Angle, and the postoperative control examination in this group showed highly positive statistical correlation with r = 0.97 correlation factor . The less increase of the curvature of the spine (an average of 7.52 %) can be expected in patients operated in the period of stagnating growth of the spine and the relationship between measured values ​​of Cobb 's Angle and the postoperative control examination in this group showed a highly positive statistical correlation (correlation factor r = 0.98) as well. Individual size of the postoperative spinal curvature do not condition the size of the possible progression of the curvature.