TY - JOUR
T1 - Are insufficient corrections a major factor in distal junctional kyphosis? A simulated analysis of cervical deformity correction using in-construct measurements
AU - International Spine Study Group (ISSG)
AU - Ani, Fares
AU - Sissman, Ethan
AU - Woo, Dainn
AU - Soroceanu, Alex
AU - Mundis, Gregory
AU - Eastlack, Robert K.
AU - Smith, Justin S.
AU - Hamilton, D. Kojo
AU - Kim, Han Jo
AU - Daniels, Alan H.
AU - Klineberg, Eric O.
AU - Neuman, Brian
AU - Sciubba, Daniel M.
AU - Gupta, Munish C.
AU - Kebaish, Khaled M.
AU - Passias, Peter G.
AU - Hart, Robert A.
AU - Bess, Shay
AU - Shaffrey, Christopher I.
AU - Schwab, Frank J.
AU - Lafage, Virginie
AU - Ames, Christopher P.
AU - Protopsaltis, Themistocles S.
N1 - Publisher Copyright:
©AANS 2024, except where prohibited by US copyright law.
PY - 2024
Y1 - 2024
N2 - OBJECTIVE The present study utilized recently developed in-construct measurements in simulations of cervical deformity surgery in order to assess undercorrection and predict distal junctional kyphosis (DJK). METHODS A retrospective review of a database of operative cervical deformity patients was analyzed for severe DJK and mild DJK. C2–lower instrumented vertebra (LIV) sagittal angle (SA) was measured postoperatively, and the correction was simulated in the preoperative radiograph in order to match the C2-LIV by using the planning software. Linear regression analysis that used C2 pelvic angle (CPA) and pelvic tilt (PT) determined the simulated PT that matched the virtual CPA. Linear regression analysis was used to determine the C2–T1 SA, C2–T4 SA, and C2–T10 SA that corresponded to DJK of 20° and cervical sagittal vertical axis (cSVA) of 40 mm. RESULTS Sixty-nine cervical deformity patients were included. Severe and mild DJK occurred in 11 (16%) and 22 (32%) patients, respectively; 3 (4%) required DJK revision. Simulated corrections demonstrated that severe and mild DJK patients had worse alignment compared to non-DJK patients in terms of cSVA (42.5 mm vs 33.0 mm vs 23.4 mm, p < 0.001) and C2-LIV SVA (68.9 mm vs 57.3 mm vs 36.8 mm, p < 0.001). Linear regression revealed the relationships between in-construct measures (C2–T1 SA, C2–T4 SA, and C2–T10 SA), cSVA, and change in DJK (all R > 0.57, p < 0.001). A cSVA of 40 mm corresponded to C2–T4 SA of 10.4° and C2–T10 SA of 28.0°. A DJK angle change of 10° corresponded to C2–T4 SA of 5.8° and C2–T10 SA of 20.1°. CONCLUSIONS Simulated cervical deformity corrections demonstrated that severe DJK patients have insufficient corrections compared to patients without DJK. In-construct measures assess sagittal alignment within the fusion separate from DJK and subjacent compensation. They can be useful as intraoperative tools to gauge the adequacy of cervical deformity correction.
AB - OBJECTIVE The present study utilized recently developed in-construct measurements in simulations of cervical deformity surgery in order to assess undercorrection and predict distal junctional kyphosis (DJK). METHODS A retrospective review of a database of operative cervical deformity patients was analyzed for severe DJK and mild DJK. C2–lower instrumented vertebra (LIV) sagittal angle (SA) was measured postoperatively, and the correction was simulated in the preoperative radiograph in order to match the C2-LIV by using the planning software. Linear regression analysis that used C2 pelvic angle (CPA) and pelvic tilt (PT) determined the simulated PT that matched the virtual CPA. Linear regression analysis was used to determine the C2–T1 SA, C2–T4 SA, and C2–T10 SA that corresponded to DJK of 20° and cervical sagittal vertical axis (cSVA) of 40 mm. RESULTS Sixty-nine cervical deformity patients were included. Severe and mild DJK occurred in 11 (16%) and 22 (32%) patients, respectively; 3 (4%) required DJK revision. Simulated corrections demonstrated that severe and mild DJK patients had worse alignment compared to non-DJK patients in terms of cSVA (42.5 mm vs 33.0 mm vs 23.4 mm, p < 0.001) and C2-LIV SVA (68.9 mm vs 57.3 mm vs 36.8 mm, p < 0.001). Linear regression revealed the relationships between in-construct measures (C2–T1 SA, C2–T4 SA, and C2–T10 SA), cSVA, and change in DJK (all R > 0.57, p < 0.001). A cSVA of 40 mm corresponded to C2–T4 SA of 10.4° and C2–T10 SA of 28.0°. A DJK angle change of 10° corresponded to C2–T4 SA of 5.8° and C2–T10 SA of 20.1°. CONCLUSIONS Simulated cervical deformity corrections demonstrated that severe DJK patients have insufficient corrections compared to patients without DJK. In-construct measures assess sagittal alignment within the fusion separate from DJK and subjacent compensation. They can be useful as intraoperative tools to gauge the adequacy of cervical deformity correction.
KW - cervical alignment
KW - cervical deformity drivers
KW - distal junctional failure
KW - distal junctional kyphosis
KW - failure mechanisms
KW - patient-reported outcome measures
KW - sagittal alignment
KW - spinal deformity correction
KW - thoracic kyphosis
KW - transition rods
UR - http://www.scopus.com/inward/record.url?scp=85192114334&partnerID=8YFLogxK
U2 - 10.3171/2023.12.SPINE23481
DO - 10.3171/2023.12.SPINE23481
M3 - Article
C2 - 38364226
AN - SCOPUS:85192114334
SN - 1547-5654
VL - 40
SP - 622
EP - 629
JO - Journal of Neurosurgery: Spine
JF - Journal of Neurosurgery: Spine
IS - 5
ER -