Effect of selective fusion on the balance of lumbar vertebrae and pelvis sagittal plane in standing and sitting position of Lenke 1 adolescent idiopathic scoliosis

English Keywords:Adolescent idiopathic scoliosis  Sagittal balance  Lumbosacral pelvic parameters  Standing position  Sitting position

English Abstract:

  【Abstract】 Objectives: To investigate the changes of lumbar spine and pelvic sagittal plane in standing and sitting positions before and after orthopedic surgery as well as at short-term follow-up of Lenke　1 adolescent idiopathic scoliosis(AIS).　Methods: A total of 24 Lenke　1　AIS patients who underwent posterior orthopedic fusion in our center from April 2013 to April 2015 was selected, aged from 11 to 15 years(average, 13.0±1.8 years), including 12 cases of Lenke　1A type, 5 cases of Lenke　1B type, and 7 cases of Lenke 1C type. Patients were divided into a selective fusion group(STF group, n=13) and a non-selective fusion group(NSTF, n=11) according to the surgical fusion segment. All patients underwent preoperative, postoperative and finalfollow-up standing and sitting full-spine positive lateral radiographs. The following parameters were measured: L3/4, L4/5 and L5/S1 intervertebral angles, sacral slope(SS), pelvis imaging parameters such as pelvic incidence(PI) and pelvic tilt(PT). The changes of sagittal parameters in standing and sitting positions were compared between immediately after surgery and at final follow-up. All patients were required to complete the 22-item Scoliosis Research Society questionnaire(SRS-22) before surgery and at final follow-up. Results: All patients had a decrease in L3/4, L4/5, L5/S1 intervertebral angle and SS, while PT increased from standing to sitting position at pre- and post-operation and final follow-up. PI remained unchanged from before to after surgery(P>0.05). There was no significant difference in the corresponding sagittal parameters between at post-operation and at final follow-up(P>0.05). There were significant differences of PT and SS between preoperation and postoperation in the STF group(P<0.05). However, In the NSTF group, there was a significant difference between the standing and sitting PT and SS preoperative(P<0.05), but no significant difference between postoperative and final follow-up(P>0.05). Before surgery, there was no significant difference in SRS-22 scores between the STF group and the NSTF group in all the four items(P>0.05). At final follow-up, there were significant differences between the STF group and the NSTF group in the two items of function and pain(P<0.05), and there was no significant difference in self-image, psychological status or postoperative satisfaction(P>0.05). Conclusions: For Lenke 1 AIS, STF not only has important value in maintaining lumbar motion, but also retains the compensatory function of pelvic posterior rotation from standing to sitting position when compared with NSTF.