How the spine differs in standing and in sitting – important considerations for correction of spinal deformity

• Published in: The spine journal 2017-06, Vol.17 (6), p.799-806
• Main Authors: Hey, Dennis, MBBS (Sing), MRCS (Ire), MMED (Orth), MCI (Sing), FRCSEd (Orth), FAMS (Orth), Teo, Alex Quok An, MBBChir (Cantab), BA (Hons), MRCS (Eng), Tan, Kimberly-Anne, Ng, Nathaniel Li Wen, MBBS (Sing), Lau, Leok-Lim, MBBChir BA (Ire), MRCS (Edin), MMED (Orth), FRCSEd (Orth), Liu, Ka-Po Gabriel, MBBCh (Ire), MSc (Ire), FRCS (Ire), FRCSEd (Orth), Wong, Hee-Kit, MBBS (Sing), MMED (Surg), FRCS (Glas), MCh (Orth) Liv, FAMS (Orth)
• Format: Article
• Language: English
• Subjects: Adult; Female; Humans; Kyphosis - diagnostic imaging; Kyphosis - surgery; Lordosis - diagnostic imaging; Lordosis - surgery; Lumbar lordosis; Male; Middle Aged; Orthopedics; Patient Positioning; Posture; Proximal junctional failure; Radiography - methods; Radiography - standards; Reference Standards; Sagittal balance; Sitting; Spinal deformity surgery; Standing
• ISSN: 1529-9430; 1878-1632
• DOI: 10.1016/j.spinee.2016.03.056

Abstract Background context The current prevailing school of thought in spinal deformity surgery is to restore sagittal balance with reference to the alignment of the spine when the patient is standing. This strategy, however, likely accounts for increased rates of proximal junctional failure. Purpose To investigate the differences between the spine in standing and sitting positions as these may elucidate reasons for deformity correction failure. Study Design/Setting A prospective, comparative study of 58 healthy patients presenting to a tertiary hospital over a 6-month period. Patient sample All patients presenting with a less than 3-month history of first episode lower back pain were included. Patients who had radicular symptoms, red flag symptoms, previous spine surgery or visible spinal deformity during forward bending test were excluded. Pregnant patients were also excluded. Outcome measures Radiographic measurements collected include sagittal vertical axis (SVA), lumbar lordosis (LL), thoracolumbar angle (TL), thoracic kyphosis (TK), cervical lordosis (CL), pelvic incidence (PI) and pelvic tilt (PT). The sagittal apex and end vertebrae of all radiographs were also recorded. Methods Basic demographic data (age, gender and ethnicity) was recorded. Lateral standing and sitting radiographs were obtained using EOS® technology. Statistical analysis was performed to compare standing and sitting parameters using Chi-square tests for categorical variables and paired t-tests for continuous variables. Results Taking the standing position as the reference point, forward displacement of the SVA occurred during sitting by a mean of 6.39±3.87cm (p