Different types of mechanical complications after surgical correction of adult spine deformity with osteotomy

AIM To determine the incidence and risk factors for mechanical complications （MC） after surgical correction of adult spinal deformity （ASD） with osteotomy.METHODSA retrospective study was performed. Inclusion criteria： Surgical correction of ASD using osteotomy; male or female; 〉 20 years old; follow-up ≥ 24 mo or revision. The MC of spine and spinal instrumentation were studied separately. Risk analysis included assessment of the association between more than 50 different characteristics （demographic, clinical, radiographic, and instrumentation） with different types of MC.RESULTSThe medical records of 94 operations in 88 subjects were analyzed： Female （68%）, mean age 58.6 （SD, 12.7） years. Cumulative incidence of MC at 2 year follow-up was 43.6%. Of these, 78% required revision （ P 〈 0.001）. The following characteristics had significant （ P ≤ 0.05） association with MC： （1） Preoperative： osteoporosis, smoking, previous spinal operation, sagittal vertical axis （SVA） 〉 100 mm, lumbar lordosis （LL） 〈 34°; （2） postoperative： SVA 〉 75 mm; operative correction： SVA 〉 75 mm, LL 〉 30°, thoracic kyphosis 〉 25°, and pelvic tilt 〉 9°; a fall; pseudarthrosis; and （3） device and surgical technique： use of previously implanted instrumentation; use of domino and/or parallel connectors; type of osteotomy （PSO vs SPO） if preoperative SVA 〈 100 mm; lumbar osteotomy location; in-situ rod contouring 〉 60°; and fxation to sacrum/pelvis.CONCLUSIONRisk of MC after surgical correction of ASD is substantial. To decrease this risk over- and/or insuffcient correction of the sagittal imbalance should be avoided.