TY - JOUR
T1 - The T4-L1-Hip Axis
T2 - Sagittal Spinal Realignment Targets in Long-Construct Adult Spinal Deformity Surgery: Early Impact
AU - International Spine Study Group
AU - Hills, Jeffrey
AU - Mundis, Gregory M.
AU - Klineberg, Eric O.
AU - Smith, Justin S.
AU - Line, Breton
AU - Gum, Jeffrey L.
AU - Protopsaltis, Themistocles S.
AU - Hamilton, D. Kojo
AU - Soroceanu, Alex
AU - Eastlack, Robert
AU - Nunley, Pierce
AU - Kebaish, Khaled M.
AU - Lenke, Lawrence G.
AU - Hostin, Richard A.
AU - Gupta, Munish C.
AU - Kim, Han Jo
AU - Ames, Christopher P.
AU - Burton, Douglas C.
AU - Shaffrey, Christopher I.
AU - Schwab, Frank J.
AU - Lafage, Virginie
AU - Lafage, Renaud
AU - Bess, Shay
AU - Kelly, Michael P.
AU - Uribe, Juan
AU - Turner, Jay
AU - Daniels, Alan
AU - Anand, Neel
AU - Fu, Kai Ming
AU - Lenke, Lawrence
AU - Chou, Dean
AU - Shaffrey, Christopher
AU - Than, Khoi
AU - Hostin, Richard
AU - Kebaish, Khaled
AU - Burton, Douglas
AU - Schwab, Frank
AU - Protopsaltis, Themistocles
AU - Passias, Peter
AU - Bess, R. Shay
AU - Kelly, Michael
AU - Fessler, Richard
AU - Traynelis, Vincent
AU - Mundis, Gregory
AU - Hart, Robert
AU - Klineberg, Eric
AU - Ames, Christopher
AU - Mumanneni, Praveen
AU - Deviren, Vedat
AU - Gum, Jeffrey
AU - Wang, Michael
AU - Park, Paul
AU - Okonkwo, David
AU - Buell, Thomas
AU - Lewis, Stephen
AU - Smith, Justin
AU - Gupta, Munish
N1 - Publisher Copyright:
© 2024 BY THE JOURNAL OF BONE AND JOINT SURGERY, INCORPORATED.
PY - 2024/12/4
Y1 - 2024/12/4
N2 - Background:Our understanding of the relationship between sagittal alignment and mechanical complications is evolving. In normal spines, the L1-pelvic angle (L1PA) accounts for the magnitude and distribution of lordosis and is strongly associated with pelvic incidence (PI), and the T4-pelvic angle (T4PA) is within 4° of the L1PA. We aimed to examine the clinical implications of realignment to a normal L1PA and T4-L1PA mismatch.Methods:A prospective multicenter adult spinal deformity registry was queried for patients who underwent fixation from the T1-T5 region to the sacrum and had 2-year radiographic follow-up. Normal sagittal alignment was defined as previously described for normal spines: L1PA = PI × 0.5 - 21°, and T4-L1PA mismatch = 0°. Mechanical failure was defined as severe proximal junctional kyphosis (PJK), displaced rod fracture, or reoperation for junctional failure, pseudarthrosis, or rod fracture within 2 years. Multivariable nonlinear logistic regression was used to define target ranges for L1PA and T4-L1PA mismatch that minimized the risk of mechanical failure. The relationship between changes in T4PA and changes in global sagittal alignment according to the C2-pelvic angle (C2PA) was determined using linear regression. Lastly, multivariable regression was used to assess associations between initial postoperative C2PA and patient-reported outcomes at 1 year, adjusting for preoperative scores and age.Results:The median age of the 247 included patients was 64 years (interquartile range, 57 to 69 years), and 202 (82%) were female. Deviation from a normal L1PA or T4-L1PA mismatch in either direction was associated with a significantly higher risk of mechanical failure, independent of age. Risk was minimized with an L1PA of PI × 0.5 - (19° ± 2°) and T4-L1PA mismatch between -3° and +1°. Changes in T4PA and in C2PA at the time of final follow-up were strongly associated (r2 = 0.96). Higher postoperative C2PA was independently associated with more disability, more pain, and worse self-image at 1 year.Conclusions:We defined sagittal alignment targets using L1PA (relative to PI) and the T4-L1PA mismatch, which are both directly modifiable during surgery. In patients undergoing long fusion to the sacrum, realignment based on these targets may lead to fewer mechanical failures.
AB - Background:Our understanding of the relationship between sagittal alignment and mechanical complications is evolving. In normal spines, the L1-pelvic angle (L1PA) accounts for the magnitude and distribution of lordosis and is strongly associated with pelvic incidence (PI), and the T4-pelvic angle (T4PA) is within 4° of the L1PA. We aimed to examine the clinical implications of realignment to a normal L1PA and T4-L1PA mismatch.Methods:A prospective multicenter adult spinal deformity registry was queried for patients who underwent fixation from the T1-T5 region to the sacrum and had 2-year radiographic follow-up. Normal sagittal alignment was defined as previously described for normal spines: L1PA = PI × 0.5 - 21°, and T4-L1PA mismatch = 0°. Mechanical failure was defined as severe proximal junctional kyphosis (PJK), displaced rod fracture, or reoperation for junctional failure, pseudarthrosis, or rod fracture within 2 years. Multivariable nonlinear logistic regression was used to define target ranges for L1PA and T4-L1PA mismatch that minimized the risk of mechanical failure. The relationship between changes in T4PA and changes in global sagittal alignment according to the C2-pelvic angle (C2PA) was determined using linear regression. Lastly, multivariable regression was used to assess associations between initial postoperative C2PA and patient-reported outcomes at 1 year, adjusting for preoperative scores and age.Results:The median age of the 247 included patients was 64 years (interquartile range, 57 to 69 years), and 202 (82%) were female. Deviation from a normal L1PA or T4-L1PA mismatch in either direction was associated with a significantly higher risk of mechanical failure, independent of age. Risk was minimized with an L1PA of PI × 0.5 - (19° ± 2°) and T4-L1PA mismatch between -3° and +1°. Changes in T4PA and in C2PA at the time of final follow-up were strongly associated (r2 = 0.96). Higher postoperative C2PA was independently associated with more disability, more pain, and worse self-image at 1 year.Conclusions:We defined sagittal alignment targets using L1PA (relative to PI) and the T4-L1PA mismatch, which are both directly modifiable during surgery. In patients undergoing long fusion to the sacrum, realignment based on these targets may lead to fewer mechanical failures.
UR - http://www.scopus.com/inward/record.url?scp=85204717177&partnerID=8YFLogxK
U2 - 10.2106/JBJS.23.00372
DO - 10.2106/JBJS.23.00372
M3 - Article
C2 - 39292767
AN - SCOPUS:85204717177
SN - 0021-9355
VL - 106
SP - e48
JO - Journal of Bone and Joint Surgery
JF - Journal of Bone and Joint Surgery
IS - 23
ER -