Browsing by Author "Khalifé, Marc"

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    ItemOpen Access
    Assessing Abnormal Proximal Junctional Angles in Adult Spinal Deformity: A Normative Data Approach to Define Proximal Junctional Kyphosis.
    (Spine, 2024-10) Khalifé, Marc; Lafage, Renaud; Daniels, Alan H; Diebo, Bassel G; Elysée, Jonathan; Ames, Christopher P; Bess, Shay R; Burton, Douglas C; Eastlack, Robert K; Gupta, Munish C; Hostin, Richard A; Kebaish, Khaled; Kim, Han-Jo; Klineberg, Eric O; Mundis, Gregory; Okonkwo, David O; Gille, Olivier; Guigui, Pierre; Ferrero, Emmanuelle; Skalli, Wafa; Assi, Ayman; Assi, Ayman; Vergari, Claudio; Shaffrey, Christopher I; Smith, Justin S; Schwab, Frank J; Lafage, Virginie; International Spine Study Group

    Study design

    Multicentric retrospective study of prospectively collected data.

    Objective

    Based on normative data from a cohort of asymptomatic volunteers, this study sought to determine the rate of abnormal values of proximal junctional angles (PJA) in adult spinal deformity (ASD) surgery patients, and compare it with PJK rate.

    Summary of background data

    Proximal junctional kyphosis (PJK) definition does not take the vertebral level into account.

    Methods

    This study included 721 healthy volunteers and 824 ASD surgery patients with 2-year postoperative follow-up. Normative values for each disc and vertebral body between T1 and T12 were analyzed, then normative values for PJA at each thoracic level were defined in the volunteer cohort as the mean±2 standard deviations. PJA abnormal values at the upper instrumented vertebra (UIV) were compared with Glattes' and Lovecchio's definitions for PJK in the ASD population at two years.

    Results

    Mean age was 37.7±16.3 in the volunteer cohort, with 50.5% of females. Mean thoracic kyphosis (TK) was -50.9±10.8°. Corridors of normality included PJA greater than 20° between T3 and T12. Mean age was 60.5±14.0 years in the ASD cohort, with 77.2% of females. Mean baseline TK was -37.4±19.9°, with a significant increase after surgery (-15.6±15.3°, P<0.001). There was 46.2% of PJK according to Glattes' versus 8.7% according to Lovecchio's and 22.9% of kyphotic PJA compared to normative values (P<0.001).

    Conclusion

    This study provides normative values for segmental and regional alignment of thoracic spine, used to describe abnormal values of PJA for each level. Using level-adjusted PJA values allows a more precise assessment of abnormal proximal angles and question the definition for PJK.

    Level of evidence

    II.
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    ItemOpen Access
    Mechanisms of lumbar spine “flattening” in adult spinal deformity: defining changes in shape that occur relative to a normative population
    (European Spine Journal, 2024-01-01) Lafage, Renaud; Mota, Frank; Khalifé, Marc; Protopsaltis, Themistocles; Passias, Peter G; Kim, Han-Jo; Line, Breton; Elysée, Jonathan; Mundis, Gregory; Shaffrey, Christopher I; Ames, Christopher P; Klineberg, Eric O; Gupta, Munish C; Burton, Douglas C; Lenke, Lawrence G; Bess, Shay; Smith, Justin S; Schwab, Frank J; Lafage, Virginie; ISSG
    Purpose: Previous work comparing ASD to a normative population demonstrated that a large proportion of lumbar lordosis is lost proximally (L1-L4). The current study expands on these findings by collectively investigating regional angles and spinal contours. Methods: 119 asymptomatic volunteers with full-body free-standing radiographs were used to identify age-and-PI models of each Vertebra Pelvic Angle (VPA) from L5 to T10. These formulas were then applied to a cohort of primary surgical ASD patients without coronal malalignment. Loss of lumbar lordosis (LL) was defined as the offset between age-and-PI normative value and pre-operative alignment. Spine shapes defined by VPAs were compared and analyzed using paired t-tests. Results: 362 ASD patients were identified (age = 64.4 ± 13, 57.1% females). Compared to their age-and-PI normative values, patients demonstrated a significant loss in LL of 17 ± 19° in the following distribution: 14.1% had “No loss” (mean = 0.1 ± 2.3), 22.9% with 10°-loss (mean = 9.9 ± 2.9), 22.1% with 20°-loss (mean = 20.0 ± 2.8), and 29.3% with 30°-loss (mean = 33.8 ± 6.0). “No loss” patients’ spine was slightly posterior to the normative shape from L4 to T10 (VPA difference of 2°), while superimposed on the normative one from S1 to L2 and became anterior at L1 in the “10°-loss” group. As LL loss increased, ASD and normative shapes offset extended caudally to L3 for the “20°-loss” group and L4 for the “30°-loss” group. Conclusion: As LL loss increases, the difference between ASD and normative shapes first occurs proximally and then progresses incrementally caudally. Understanding spinal contour and LL loss location may be key to achieving sustainable correction by identifying optimal and personalized postoperative shapes.
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    ItemOpen Access
    Revision Strategy for Proximal Junctional Failure: Combined Effect of Proximal Extension and Focal Correction.
    (Global spine journal, 2024-05) Lafage, Renaud; Kim, Han-Jo; Eastlack, Robert K; Daniels, Alan H; Diebo, Bassel G; Mundis, Greg; Khalifé, Marc; Smith, Justin S; Bess, Shay R; Shaffrey, Christopher I; Ames, Christopher P; Burton, Douglas C; Gupta, Munish C; Klineberg, Eric O; Schwab, Frank J; Lafage, Virginie; ISSG

    Study design

    Retrospective review of a prospectively-collected multicenter database.

    Objectives

    The objective of this study was to determine optimal strategies in terms of focal angular correction and length of proximal extension during revision for PJF.

    Methods

    134 patients requiring proximal extension for PJF were analyzed in this study. The correlation between amount of proximal junctional angle (PJA) reduction and recurrence of proximal junctional kyphosis (PJK) and/or PJF was investigated. Following stratification by the degree of PJK correction and the numbers of levels extended proximally, rates of radiographic PJK (PJA >28° & ΔPJA >22°), and recurrent surgery for PJF were reported.

    Results

    Before revision, mean PJA was 27.6° ± 14.6°. Mean number of levels extended was 6.0 ± 3.3. Average PJA reduction was 18.8° ± 18.9°. A correlation between the degree of PJA reduction and rate of recurrent PJK was observed (r = -.222). Recurrent radiographic PJK (0%) and clinical PJF (4.5%) were rare in patients undergoing extension ≥8 levels, regardless of angular correction. Patients with small reductions (<5°) and small extensions (<4 levels) experienced moderate rates of recurrent PJK (19.1%) and PJF (9.5%). Patients with large reductions (>30°) and extensions <8 levels had the highest rate of recurrent PJK (31.8%) and PJF (16.0%).

    Conclusion

    While the degree of focal PJK correction must be determined by the treating surgeon based upon clinical goals, recurrent PJK may be minimized by limiting reduction to <30°. If larger PJA correction is required, more extensive proximal fusion constructs may mitigate recurrent PJK/PJF rates.
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    ItemOpen Access
    The Contribution of Lower Limbs to Pelvic Tilt: A Baseline and Postoperative Full-Body Analysis
    Khalifé, Marc; Lafage, Renaud; Diebo, Bassel; Daniels, Alan; Gupta, Munish; Ames, Christopher; Bess, Shay; Burton, Douglas; Kebaish, Khaled; Kelly, Michael; Kim, Han-Jo; Klineberg, Eric; Lenke, Lawrence; Lewis, Stephen; Passias, Peter; Shaffrey, Christopher; Smith, Justin S; Schwab, Frank; Lafage, Virginie
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    ItemOpen Access
    What Factors Predict the Risk of Proximal Junctional Failure in the Long Term, Demographic, Surgical, or Radiographic?: Results From a Time-dependent ROC Curve.
    (Spine, 2019-06) Yang, Jingyan; Khalifé, Marc; Lafage, Renaud; Kim, Han Jo; Smith, Justin; Shaffrey, Christopher I; Burton, Douglas C; Ames, Christopher P; Mundis, Gregory M; Hostin, Richard; Bess, Shay; Klineberg, Eric O; Hart, Robert AA; Schwab, Frank J; Lafage, Virginie; International Spine Study Group (ISSG)

    Study design

    Retrospective review of prospective multicenter database.

    Objective

    To identify an optimal set of factors predicting the risk of proximal junctional failure (PJF) while taking the time dependency of PJF and those factors into account.

    Summary of background data

    Surgical correction of adult spinal deformity (ASD) can be complex and therefore, may come with high revision rates due to PJF.

    Methods

    Seven hundred sixty-three operative ASD patients with a minimum of 1-year follow-up were included. PJF was defined as any type of proximal junctional kyphosis (PJK) requiring revision surgery. Time-dependent ROC curves were estimated with corresponding Cox proportional hazard models. The predictive abilities of demographic, surgical, radiographic parameters, and their possible combinations were assessed sequentially. The area under the curve (AUC) was used to evaluate models' performance.

    Results

    PJF occurred in 42 patients (6%), with a median time to revision of approximately 1 year. Larger preoperative pelvic tilt (PT) (hazard ratio [HR]=1.044, P = 0.034) significantly increased the risk of PJF. With respect to changes in the radiographic parameters at 6-week postsurgery, larger differences in pelvic incidence-lumbar lordosis (PI-LL) mismatch (HR = 0.924, P = 0.002) decreased risk of PJF. The combination of demographic, surgical, and radiographic parameters has the best predictive ability for the occurrence of PJF (AUC = 0.863), followed by demographic along with radiographic parameters (AUC = 0.859). Both models' predictive ability was preserved over time.

    Conclusions

    Over correction increased the risk of PJF. Radiographic along with demographic parameters have shown the approximately equivalent predictive ability for PJF over time as with the addition of surgical parameters. Radiographic rather than surgical factors may be of particular importance in predicting the development of PJF over time. These results set the groundwork for risk stratification and corresponding prophylactic interventions for patients undergoing ASD surgery.

    Level of evidence

    4.