Browsing by Author "Bronsard, Nicolas"
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Item Open Access Cervical sagittal deformity develops after PJK in adult thoracolumbar deformity correction: radiographic analysis utilizing a novel global sagittal angular parameter, the CTPA.(European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 2017-04) Protopsaltis, Themistocles; Bronsard, Nicolas; Soroceanu, Alex; Henry, Jensen K; Lafage, Renaud; Smith, Justin; Klineberg, Eric; Mundis, Gregory; Kim, Han Jo; Hostin, Richard; Hart, Robert; Shaffrey, Christopher; Bess, Shay; Ames, Christopher; International Spine Study GroupPurpose
To describe reciprocal changes in cervical alignment after adult spinal deformity (ASD) correction and subsequent development of proximal junctional kyphosis (PJK). This study also investigated these changes using two novel global sagittal angular parameters, cervical-thoracic pelvic angle (CTPA) and the T1 pelvic angle (TPA).Methods
Multicenter, retrospective consecutive case series of ASD patients undergoing thoracolumbar three-column osteotomy (3CO) with fusion to the pelvis. Radiographs were analyzed at baseline and 1 year post-operatively. Patients were substratified into upper thoracic (UT; UIV T6 and above) and lower thoracic (LT; UIV below T6). PJK was defined by >10° angle between UIV and UIV + 2 and >10° change in the angle from baseline to post-op.Results
PJK developed in 29 % (78 of 267) of patients. CTPA was linearly correlated with cervical plumbline (CPL) as a measure of cervical sagittal alignment (R = 0.826, p < 0.001). PJK patients had significantly greater post-operative CTPA and SVA than patients without PJK (NPJK) (p = 0.042; p = 0.021). For UT (n = 141) but not LT (n = 136), PJK patients at 1 year had larger CTPA (4.9° vs. 3.7°, p = 0.015) and CPL (5.1 vs. 3.8 cm, p = 0.022) than NPJK patients, despite similar corrections in PT and PI-LL.Conclusions
The prevalence of PJK was 29 % at 1 year follow-up. CTPA, which correlates with CPL as a global analog of cervical sagittal balance, and TPA describe relative proportions of cervical and thoracolumbar deformities. Patients who develop PJK in the upper thoracic spine after thoracolumbar 3CO also develop concomitant cervical sagittal deformity, with increases in CPL and CTPA.Item Open Access T1 Slope Minus Cervical Lordosis (TS-CL), the Cervical Answer to PI-LL, Defines Cervical Sagittal Deformity in Patients Undergoing Thoracolumbar Osteotomy.(International journal of spine surgery, 2018-06) Protopsaltis, Themistocles; Terran, Jamie; Soroceanu, Alex; Moses, Michael J; Bronsard, Nicolas; Smith, Justin; Klineberg, Eric; Mundis, Gregory; Kim, Han Jo; Hostin, Richard; Hart, Robert; Shaffrey, Christopher; Bess, Shay; Ames, Christopher; Schwab, Frank; Lafage, Virginie; INTERNATIONAL SPINE STUDY GROUPBackground
Cervical kyphosis and C2-C7 plumb line (CPL) are established descriptors of cervical sagittal deformity (CSD). Reciprocal changes in these parameters have been demonstrated in thoracolumbar deformity correction. The purpose of this study was to investigate the development of CSD, using T1 slope minus cervical lordosis (TS-CL) to define CSD and to correlate TS-CL and a novel global sagittal parameter, cervical-thoracic pelvic angle (CTPA), with CPL.Methods
A multicenter, retrospective analysis of patients with thoracolumbar deformity undergoing three-column osteotomy was performed. Preoperative and postoperative cervical parameters were investigated. Linear regression for postoperative values resulted in a CPL of 4 cm corresponding to a TS-CL threshold of 17°. Patients were classified based on postoperative TS-CL into uncompensated (TS-CL > 17°) or compensated cohorts (TS-CL < 17°); the two were compared using an unpaired t test. Logistic regression modeling was used to determine predictors of postoperative CSD.Results
A total of 223 patients with thoracolumbar deformity (mean age, 57.56 years) were identified. CTPA correlated with CPL (preoperative r = .85, postoperative r = .69). TS-CL correlated with CTPA (preoperative r = .52, postoperative r = .37) and CPL (preoperative r = .52; postoperative r = .37). CSD had greater preoperative CPL (P < .001) and CTPA (P < .001). The compensated cohort had a decrease in TS-CL (from 10.2 to 8.0) with sagittal vertical axis (SVA) correction, whereas the uncompensated had an increase in TS-CL (from 22.3 to 26.8) with all P < .001. Reciprocal change was demonstrated in the compensated group given that CL decreased with SVA correction (r = .39), but there was no such correlation in the uncompensated. Positive predictors of postoperative CSD included baseline TS-CL > 17° (P = .007), longer fusion (P = .033), and baseline CTPA (P = .029).Conclusions
TS-CL and CTPA correlated significantly with established sagittal balance measures. Whereas reciprocal change in cervical and thoracolumbar alignment was demonstrated in the compensated cohort, the uncompensated population had progression of their cervical deformities after three-column osteotomy.Clinical relevance
The balance between TS-CL mirrors the relationship between pelvic incidence minus lumbar lordosis in defining deformities of their respective spinal regions.Item Open Access TheT1 pelvic angle, a novel radiographic measure of global sagittal deformity, accounts for both spinal inclination and pelvic tilt and correlates with health-related quality of life.(The Journal of bone and joint surgery. American volume, 2014-10) Protopsaltis, Themistocles; Schwab, Frank; Bronsard, Nicolas; Smith, Justin S; Klineberg, Eric; Mundis, Gregory; Ryan, Devon J; Hostin, Richard; Hart, Robert; Burton, Douglas; Ames, Christopher; Shaffrey, Christopher; Bess, Shay; Errico, Thomas; Lafage, Virginie; International Spine Study GroupBackground
Adult spinal deformity is a prevalent cause of pain and disability. Established measures of sagittal spinopelvic alignment such as sagittal vertical axis and pelvic tilt can be modified by postural compensation, including pelvic retroversion, knee flexion, and the use of assistive devices for standing. We introduce the T1 pelvic angle, a novel measure of sagittal alignment that simultaneously accounts for both spinal inclination and pelvic retroversion. The purpose of this study was to investigate the relationship of the T1 pelvic angle and other established sagittal alignment measures and to correlate these parameters with health-related quality-of-life measures.Methods
This is a multicenter, prospective, cross-sectional analysis of consecutive patients with adult spinal deformity. Inclusion criteria were adult spinal deformity, an age of greater than eighteen years, and any of the following: scoliosis, a Cobb angle of ≥ 20°, sagittal vertical axis of ≥ 5 cm, thoracic kyphosis of ≥ 60°, and pelvic tilt of ≥ 25°. Clinical measures of disability included the Oswestry Disability Index (ODI), Scoliosis Research Society (SRS)-22, and Short Form-36 (SF-36) questionnaires.Results
Five hundred and fifty-nine consecutive patients with adult spinal deformity (mean age, 52.5 years) were enrolled. The T1 pelvic angle correlated with the sagittal vertical axis (r = 0.837), pelvic incidence minus lumbar lordosis (r = 0.889), and pelvic tilt (0.933). Categorizing the patients by increasing T1 pelvic angle (<10°, 10° to 20°, 21° to 30°, and > 30°) revealed a significant and progressive worsening in health-related quality of life (p < 0.001 for all). The T1 pelvic angle and sagittal vertical axis correlated with the ODI (0.435 and 0.455), SF-36 Physical Component Summary (-0.445 and -0.458), and SRS (-0.358 and -0.383) (p < 0.001 for all). Utilizing a linear regression analysis, a T1 pelvic angle of 20° corresponded to a severe disability (an ODI of >40), and the meaningful change in T1 pelvic angle corresponding to one minimal clinically important difference was 4.1° on the ODI.Conclusions
The T1 pelvic angle correlates with health-related quality of life in patients with adult spinal deformity. The T1 pelvic angle is related to both pelvic tilt and sagittal vertical axis; however, unlike sagittal vertical axis, it does not vary on the basis of the extent of pelvic retroversion or patient support in standing. Since the T1 pelvic angle is an angular and not a linear measure, it does not require calibration of the radiograph. Thus, the T1 pelvic angle measures sagittal deformity independent of many postural compensatory mechanisms, and it can be useful as a preoperative planning tool, with a target T1 pelvic angle of < 14°.Level of evidence
Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.