Spine - 2026-03-12 - Journal Article
Height, Not Weight, is an Independent Predictor of Proximal Junctional Kyphosis After Adult Spinal Deformity Surgery.
Sulieman A, Sahhar M, Beeram I, Diebo BG, Lafage V, Lafage R, Line BG, Hamilton DK, Hostin R, Passias PG, Klineberg EO, Smith JS, Gum JL, Mullin J, Buell TJ, Soroceanu A, Kim HJ, Eastlack RK, Daniels AH, Mundis GM, Protopsaltis TS, Gupta MC, Anand N, Okonkwo DO, Turner JD, Schwab FJ, Shaffrey CI, Lewis SJ, Mummaneni PV, Ames CP, Lenke LG, Bess S, Lee SH, Kebaish KM, International Spine Study Group
Topics
Key Takeaway
In 904 ASD patients, taller height (peak risk ~179 cm) was an independent predictor of PJK (14% incidence, p=0.03), while weight and BMI were not.
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Summary
This study examined whether height and weight independently predict PJK after ASD surgery using a multicenter prospective registry (2008–2020). A generalized additive model adjusted for age, osteoporosis, UIV level, fusion length, postoperative PI-LL, and T1 pelvic angle identified taller height as an independent predictor (p=0.03), with PJK risk peaking at ~179 cm. Weight showed no independent effect and no significant interaction with height; overall PJK incidence was 14% (131/904).
Key Limitation
Follow-up duration is unreported, so the study cannot distinguish whether height-related PJK risk is driven by early construct failure or progressive junctional degeneration over time.
Original Abstract
STUDY DESIGN
Retrospective review of prospectively collected, multicenter data.
OBJECTIVE
To assess associations between patient height and weight independently and interactively with the incidence of proximal junctional kyphosis (PJK) after surgical treatment of adult spine deformity.
SUMMARY OF BACKGROUND DATA
Body mass index has traditionally been used to assess the influence of body composition on surgical outcomes, but the individual effects of height and weight have not been studied in relation to PJK.
METHODS
We compared baseline demographic characteristics, radiographic measurements, and perioperative variables between patients who developed PJK after adult spinal deformity surgery between 2008 and 2020 and those who did not. Using a generalized additive model with a logistic link function, we modeled height and weight and their interaction as smooth terms to capture potential nonlinear effects on PJK risk. Multivariate analysis was adjusted for age, history of osteoporosis, upper instrumented vertebra, number of levels fused, and postoperative pelvic incidence minus lumbar lordosis and T1 pelvic angle.
RESULTS
Of 904 included patients, the median age was 65 years (interquartile range: 58-71), and 76% were female. PJK developed in 131 patients (14%). Baseline characteristics, including frailty, comorbidities, and radiographic measures, did not differ significantly between the PJK and non-PJK groups. Taller height was a predictor of PJK (P=.03). In contrast, weight was not an independent predictor, and there was no significant interaction between height and weight. The incidence of PJK peaked at a height of approximately 179 cm before plateauing.
CONCLUSIONS
Taller height, but not weight, was associated with developing PJK after adult spinal deformity surgery. These findings underscore the importance of considering patient height during surgical planning.