Browsing by Author "Quinn, John C"

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    ItemOpen Access
    A Pilot Study on Posterior Polyethylene Tethers to Prevent Proximal Junctional Kyphosis After Multilevel Spinal Instrumentation for Adult Spinal Deformity.
    (Operative neurosurgery (Hagerstown, Md.), 2019-02) Buell, Thomas J; Buchholz, Avery L; Quinn, John C; Bess, Shay; Line, Breton G; Ames, Christopher P; Schwab, Frank J; Lafage, Virginie; Shaffrey, Christopher I; Smith, Justin S
    BACKGROUND:Proximal junctional kyphosis (PJK) is a common problem after multilevel spine instrumentation. OBJECTIVE:To determine if junctional tethers reduce PJK after multilevel instrumented surgery for adult spinal deformity (ASD). METHODS:ASD patients who underwent posterior instrumented fusion were divided into 3 groups: no tether (NT), polyethylene tether-only (TO; tied securely through the spinous processes of the uppermost instrumented vertebra [UIV] + 1 and UIV-1), and tether with crosslink (TC; passed through the spinous process of UIV+1 and tied to a crosslink between UIV-1 and UIV-2). PJK was defined as proximal junctional angle ≥ 10° and ≥ 10° greater than the corresponding preoperative measurement. RESULTS:One hundred eighty-four (96%) of 191 consecutive patients achieved minimum 3-mo follow-up (mean = 20 mo [range:3-56 mo]; mean age = 66 yr; 67.4% female). There were no significant differences between groups based on demographic, surgical, and sagittal radiographic parameters. PJK rates were 45.3% (29/64), 34.4% (22/64), and 17.9% (10/56) for NT, TO, and TC, respectively. PJK rate for all tethered patients (TO + TC; 26.7% [32/120]) was significantly lower than NT (P = .011). PJK rate for TC was significantly lower than NT (P = .001). Kaplan-Meier analysis showed significant time-dependent PJK reduction for TC vs NT (log rank test, P = .010). Older age and greater change in lumbar lordosis were independent predictors of PJK, while junctional tethers had a significant protective effect. CONCLUSION:Junctional tethers significantly reduced occurrence of PJK. This difference was progressive from NT to TO to TC, but only reached pairwise significance for NT vs TC. This suggests potential benefit of tethers to reduce PJK, and that future prospective studies are warranted.
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    Alignment Risk Factors for Proximal Junctional Kyphosis and the Effect of Lower Thoracic Junctional Tethers for Adult Spinal Deformity.
    (World neurosurgery, 2019-01) Buell, Thomas J; Chen, Ching-Jen; Quinn, John C; Buchholz, Avery L; Mazur, Marcus D; Mullin, Jeffrey P; Nguyen, James H; Taylor, Davis G; Bess, Shay; Line, Breton G; Ames, Christopher P; Schwab, Frank J; Lafage, Virginie; Shaffrey, Christopher I; Smith, Justin S

    Objective

    The aims of this retrospective cohort study were to 1) identify new alignment risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) patients with lower thoracic upper instrumented vertebra (UIV) and 2) determine the effect of junctional tethers on PJK and UIV alignment.

    Methods

    We analyzed consecutive ASD patients who underwent posterior instrumented fusion with lower thoracic UIV (T9-T11). Posteriorly anchored junctional tethers were used more recently for ligamentous augmentation to prevent PJK. In addition to regional and global parameters, upper segmental lumbar lordosis (ULL) versus lower segmental lumbar lordosis and UIV angle (measured from UIV inferior endplate to horizontal) were assessed. Primary outcome of PJK was defined as proximal junctional angle >10° and >10° greater than the corresponding preoperative measurement. Univariable and multivariable analyses were performed.

    Results

    The study cohort comprised 120 ASD patients (mean age, 67 years) with minimum 1-year follow-up. Preoperative ULL (P = 0.034) and UIV angle (P = 0.026) were associated with PJK. No independent preoperative alignment risk factors of PJK were identified in multivariable analysis. Tether use was protective against PJK (odds ratio, 0.063 [0.016-0.247]; P < 0.001). PJK in tethered patients was more common with greater postoperative ULL (P = 0.047) and UIV angle (P = 0.026).

    Conclusions

    Junctional tethers significantly reduced PJK in ASD patients with lower thoracic UIV. In tethered patients, PJK was more common with greater postoperative lordosis of the upper lumbar spine and greater UIV angle. This finding suggests potential benefit of tethers to mitigate effects of segmental lumbar and focal UIV malalignment that may occur after deformity surgery.
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    Extended Asymmetrical Pedicle Subtraction Osteotomy for Adult Spinal Deformity: 2-Dimensional Operative Video.
    (Operative neurosurgery (Hagerstown, Md.), 2019-02) Buell, Thomas J; Buchholz, Avery L; Quinn, John C; Mullin, Jeffrey P; Garces, Juanita; Mazur, Marcus D; Shaffrey, Mark E; Yen, Chun-Po; Shaffrey, Christopher I; Smith, Justin S
    Pedicle subtraction osteotomy (PSO) is an effective technique to correct fixed sagittal malalignment. A variation of this technique, the "trans-discal" or "extended" PSO (Schwab grade IV osteotomy), involves extending the posterior wedge resection of the index vertebra to include the superior adjacent disc for radical discectomy. The posterior wedge may be resected in asymmetric fashion to correct concurrent global coronal malalignment.This video illustrates the technical nuances of an extended asymmetrical lumbar PSO for adult spinal deformity. A 62-yr-old female with multiple prior lumbar fusions presented with worsening back pain and posture. Preoperative scoliosis X-rays demonstrated severe global sagittal and coronal malalignment (sagittal vertical axis [SVA, C7-plumbline] of 13.5 cm, pelvic incidence [PI] of 60°, lumbar lordosis [LL] of 14° [in kyphosis], pelvic tilt [PT] of 61°, thoracic kyphosis [TK] of 18°, and rightward coronal shift of 9.3 cm). The patient gave informed consent to surgery and for use of her imaging for medical publication. Briefly, surgery first involved transpedicular instrumentation from T10 to S1 with bilateral iliac screw fixation, and then T11-12 and T12-L1 Smith-Petersen osteotomies were performed. Next, an extended asymmetrical L4 PSO was performed and a 12° lordotic cage (9 × 14 × 40 mm) was placed at the PSO defect. Rods were placed from T10 to iliac bilaterally, and accessory supplemental rods spanning the PSO were attached. Postoperative scoliosis X-rays demonstrated improved alignment: SVA 5.5 cm, PI 60°, LL 55°, PT 36°, TK 37°, and 3.7 cm of rightward coronal shift. The patient had uneventful recovery.
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    Importance of Sagittal Alignment of the Cervical Spine in the Management of Degenerative Cervical Myelopathy.
    (Neurosurgery clinics of North America, 2018-01) Buell, Thomas J; Buchholz, Avery L; Quinn, John C; Shaffrey, Christopher I; Smith, Justin S
    Cervical spine sagittal malalignment correlates with worse symptoms and outcomes in patients with degenerative cervical myelopathy (DCM), and should influence surgical management. An anterior versus posterior surgical approach may not significantly change outcomes in patients with preoperative lordosis; however, most studies suggest improved neurologic recovery among kyphotic patients after adequate correction of local sagittal alignment through an anterior or combined anterior-posterior approach. There are no comprehensive guidelines for DCM management in the setting of cervical malalignment; therefore, surgical management should be tailored to individual patients and decisions made at the discretion of treating surgeons with attention to basic principles.