TY - JOUR
T1 - Cervical, Thoracic, and Spinopelvic Compensation After Proximal Junctional Kyphosis (PJK)
T2 - Does Location of PJK Matter?
AU - the International Spine Study Group(ISSG)
AU - Kim, Han Jo
AU - York, Philip J.
AU - Elysee, Jonathan C.
AU - Shaffrey, Christopher
AU - Burton, Douglas C.
AU - Ames, Christopher P.
AU - Mundis, Gregory M.
AU - Hostin, Richard
AU - Bess, Shay
AU - Klineberg, Eric
AU - Smith, Justin S.
AU - Passias, Peter
AU - Schwab, Frank
AU - Lafage, Renaud
PY - 2020/2/1
Y1 - 2020/2/1
N2 - Study Design: Retrospective case series. Objective: Compensatory changes above a proximal junctional kyphosis (PJK) have not been defined. Understanding these mechanisms may help determine optimal level selection when performing revision for PJK. This study investigates how varying PJK location changes proximal spinal alignment. Methods: Patients were grouped by upper instrumented vertebrae (UIV): lower thoracic (LT; T8-L1) or upper thoracic (UT; T1-7). Alignment parameters were compared. Correlation analysis was performed between PJK magnitude and global/cervical alignment. Results: A total of 369 patients were included; mean age of 63 years, body mass index 28, and 81% female, LT (n = 193) versus UT (n = 176). The rate of radiographic PJK was 49%, higher in the LT group (55% vs 42%, P =.01). The UT group displayed significant differences in all cervical radiographic parameters (P <.05) between PJK versus non-PJK patients, while the LT group displayed significant differences in T1S and C2-T3 sagittal vertical axis (SVA) (CTS). In comparing UT versus LT patients, UT had more posterior global alignment (smaller TPA [T1 pelvic angle], SVA, and larger PT [pelvic tilt]) and larger anterior cervical alignment (greater cSVA [cervical SVA], T1S-CL [T1 slope–cervical lordosis] mismatch, CTS) compared to LT. Correlation analysis of PJK magnitude and location demonstrated a correlation with increases in CL, T1S, and CTS in the UT group. In the LT group, PT increased with PJK angle (r = 0.17) and no significant correlations were noted to SVA, cSVA, or T1S-CL. Conclusions: PJK location influences compensation mechanisms of the cervical and thoracic spine. LT PJK results in increased PT and CL with decreased CTS. UT PJK increases CL to counter increases in T1S with continued T1S-CL mismatch and elevated cSVA.
AB - Study Design: Retrospective case series. Objective: Compensatory changes above a proximal junctional kyphosis (PJK) have not been defined. Understanding these mechanisms may help determine optimal level selection when performing revision for PJK. This study investigates how varying PJK location changes proximal spinal alignment. Methods: Patients were grouped by upper instrumented vertebrae (UIV): lower thoracic (LT; T8-L1) or upper thoracic (UT; T1-7). Alignment parameters were compared. Correlation analysis was performed between PJK magnitude and global/cervical alignment. Results: A total of 369 patients were included; mean age of 63 years, body mass index 28, and 81% female, LT (n = 193) versus UT (n = 176). The rate of radiographic PJK was 49%, higher in the LT group (55% vs 42%, P =.01). The UT group displayed significant differences in all cervical radiographic parameters (P <.05) between PJK versus non-PJK patients, while the LT group displayed significant differences in T1S and C2-T3 sagittal vertical axis (SVA) (CTS). In comparing UT versus LT patients, UT had more posterior global alignment (smaller TPA [T1 pelvic angle], SVA, and larger PT [pelvic tilt]) and larger anterior cervical alignment (greater cSVA [cervical SVA], T1S-CL [T1 slope–cervical lordosis] mismatch, CTS) compared to LT. Correlation analysis of PJK magnitude and location demonstrated a correlation with increases in CL, T1S, and CTS in the UT group. In the LT group, PT increased with PJK angle (r = 0.17) and no significant correlations were noted to SVA, cSVA, or T1S-CL. Conclusions: PJK location influences compensation mechanisms of the cervical and thoracic spine. LT PJK results in increased PT and CL with decreased CTS. UT PJK increases CL to counter increases in T1S with continued T1S-CL mismatch and elevated cSVA.
KW - cervical deformity
KW - complications
KW - proximal junctional kyphosis
KW - radiographic evaluation
KW - spinopelvic compensation
KW - thoracic compensation
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UR - http://www.scopus.com/inward/citedby.url?scp=85078564420&partnerID=8YFLogxK
U2 - 10.1177/2192568219879085
DO - 10.1177/2192568219879085
M3 - Article
AN - SCOPUS:85078564420
VL - 10
SP - 6
EP - 12
JO - Global Spine Journal
JF - Global Spine Journal
SN - 2192-5682
IS - 1
ER -