A multicenter analysis of factors associated with change in height after adolescent idiopathic scoliosis deformity surgery in 447 patients.

By London Spine
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A multicenter analysis of factors associated with change in height after adolescent idiopathic scoliosis deformity surgery in 447 patients.

J Neurosurg Spine. 2013 Mar;18(3):298-302

Authors: Hwang SW, Samdani AF, Lonner BS, Marks MC, Bastrom TP, Betz RR, Cahill PJ

Abstract
Object In the surgical management of adolescent idiopathic scoliosis (AIS), patients are often preoperatively informed that they will gain height as a result of their surgery. However, current estimations conflict significantly and do not have any clinical correlation. The authors developed a formula that would predict postoperative gains in height after deformity correction in AIS. Methods A large, multicenter, prospective database was retrospectively queried for AIS patients with Lenke Type 1, 2, or 3 curves having undergone posterior spinal fusion alone. A univariate and multivariate analysis was performed to identify which factors contributed significantly to changes in height. Results Four hundred forty-seven patients were included in the series. Factors correlating with changes in postoperative height included: upper thoracic curve magnitude, main thoracic curve magnitude, lumbar curve magnitude, T2-12 kyphosis, T5-12 kyphosis, curve flexibility, number of levels fused, presence of Ponte osteotomies, total preoperative coronal Cobb angle, change in coronal curve magnitude, total preoperative sagittal curvature, change in sagittal curvature, and thoracic curve correction. When combined in a multivariate regression analysis the following variables remained significant: thoracic curve magnitude (p < 0.01), number of levels fused (p < 0.01), change in total sagittal curvature (p < 0.01), and the presence of osteotomies (p = 0.03). The contribution from the thoracic curve magnitude was significantly greater than any of the other parameters identified (R2 = 0.140). Change in height (in cm) = ([thoracic curve magnitude × 0.039] + [number of levels fused × 0.193] – [change in sagittal curvature × 0.033] + [x × 0.375]) – 1.858, where x = 1 if 1 or more osteotomies were performed and x = 0 if no osteotomy was performed. Conclusions The authors’ results suggest that changes in the coronal plane contribute more significantly to height changes than those in the sagittal plane and approximately 0.39 cm of height gain can be expected for each 10° of coronal curve preoperatively. Unfortunately, a significant fraction of the postoperative height changes cannot be predicted by currently measured parameters.

PMID: 23330975 [PubMed – in process]

Commentary on an article by Rick Delamarter, MD, et al.: “Prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement compared with circumferential arthrodesis for the treatment of two-level degenerative lumbar disc disease. Results at twenty-four months”.

By London Spine

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Commentary on an article by Rick Delamarter, MD, et al.: “Prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement compared with circumf…

Prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement compared with circumferential arthrodesis for the treatment of two-level lumbar degenerative disc disease: results at twenty-four months.

By London Spine
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Prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement compared with circumferential arthrodesis for the treatment of two-level lumbar degenerative disc disease: results at twenty-four months.

J Bone Joint Surg Am. 2011 Apr 20;93(8):705-15

Authors: Delamarter R, Zigler JE, Balderston RA, Cammisa FP, Goldstein JA, Spivak JM

Abstract
BACKGROUND: Disc replacement arthroplasty previously has been shown to be an effective alternative to spine fusion for the treatment of single-level lumbar degenerative disc disease. The purpose of the present study was to determine the twenty-four-month results of a clinical trial of the ProDisc-L total disc replacement as compared with spinal fusion for the treatment of degenerative disc disease at two contiguous vertebral levels from L3 to S1.
METHODS: A total of 237 patients were treated in a randomized controlled trial designed as a non-inferiority study for regulatory application purposes. Blocked randomization was performed with use of a 2:1 ratio of total disc arthroplasty to circumferential arthrodesis. Evaluations, including patient self-assessments, physical and neurological examinations, and radiographic examinations, were performed preoperatively, six weeks postoperatively, and three, six, twelve, eighteen, and twenty-four months postoperatively.
RESULTS: At twenty-four months, 58.8% (eighty-seven) of 148 patients in the total disc replacement group were classified as a statistical success, compared with 47.8% (thirty-two) of sixty-seven patients in the arthrodesis group; non-inferiority was demonstrated. The mean Oswestry Disability Index in both groups significantly improved from baseline (p < 0.0001); the mean percentage improvement for the total disc replacement group was significantly better than that for the arthrodesis group (p = 0.0282). An established clinical criterion for success, a ≥15-point improvement in the Oswestry Disability Index from baseline, occurred in 73.2% (109) of 149 patients in the total disc replacement group and 59.7% (thirty-seven) of sixty-two patients in the arthrodesis group. The Short Form-36 physical component scores were significantly better for the total disc replacement group as compared with the arthrodesis group (p = 0.0141 at twenty-four months). Visual analog scale scores for satisfaction significantly favored total disc replacement from three to twenty-four months. At twenty-four months, 78.2% (111) of 142 patients in the total disc replacement group and 62.1% (thirty-six) of fifty-eight patients in the arthrodesis group responded “yes” when asked if they would have the same surgery again. Lumbar spine range of motion on radiographs averaged 7.8° at the superior disc and 6.2° at the inferior disc in patients with total disc replacement. Reduction in narcotics usage significantly favored the total disc replacement group at twenty-four months after surgery (p = 0.0020).
CONCLUSIONS: Despite the relatively short duration of follow-up and design limitations, the present study suggests that two-level lumbar disc arthroplasty is an alternative to and offers clinical advantages in terms of pain relief and functional recovery in comparison with arthrodesis. Longer-term follow-up is needed to determine the risks for implant wear and/or degenerative segment changes.

PMID: 21398574 [PubMed – indexed for MEDLINE]

Five-year results of the prospective, randomized, multicenter, Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement versus circumferential arthrodesis for the treatment of single-level degenerative disc disease.

By London Spine
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Five-year results of the prospective, randomized, multicenter, Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement versus circumferential arthrodesis for the treatment of single-level degenerative disc disease.

J Neurosurg Spine. 2012 Dec;17(6):493-501

Authors: Zigler JE, Delamarter RB

Abstract
OBJECT: The purpose of this study was to evaluate the long-term safety and effectiveness of the ProDisc-L total disc replacement (TDR) as part of an FDA-mandated postmarket approval study. This report summarizes the clinical findings after 5 years of follow-up.
METHODS: Two hundred thirty-six patients were treated and followed up for 5 years; 161 TDRs and 75 fusions had been performed in these patients. The primary outcome was a 10-component success end point. Secondary outcome measures included neurological status, secondary surgery, Oswestry Disability Index (ODI), 36-Item Short Form Health Survey (SF-36), visual analog scale (VAS) assessing pain and satisfaction, radiographic data, narcotic use, activity, and recreation status. Patients were monitored through their 5-year postoperative visits under the FDA postmarket surveillance provisions in the original investigational device exemption approval.
RESULTS: The overall follow-up rate at 5 years was 81.8%. Study success demonstrated that TDR was noninferior to fusion with a 12.5% margin (p = 0.0099). Both TDR and fusion treatment groups maintained significant improvement on the ODI at 5 years compared with baseline (p < 0.0001). Secondary surgeries at the index level were performed in 12% of fusion patients and 8% of TDR patients. Radiographically, none of the TDRs developed spontaneous fusion. The segmental range of motion following TDR remained within normal range, although it decreased by approximately 0.5° in years 3 to 5. The VAS pain scores decreased from preoperative values by 48% in both treatment groups at 5 years. Patient satisfaction remained high in both groups (77%), while the percentage of patients indicating that they would have the surgery again was higher in TDR patients (82.5%) than in fusion patients (68.0%).
CONCLUSIONS: Patients in both groups maintained significant improvement during the 5-year follow-up. The TDR group had significantly better improvement on some scales. Although TDR patients avoid the stiffness of fusion and are more satisfied than fusion patients, both fusion and TDR are reasonable surgical options in this specific patient population.

PMID: 23082846 [PubMed – indexed for MEDLINE]