Blake C Meza1,2, Suken A Shah3, Michael G Vitale4, Peter F Sturm5, Scott J Luhmann6, Jason B Anari7. 1. Department of Orthopaedic Surgery, The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA, 19104, USA. 2. Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA. 3. Department of Orthopaedic Surgery, Nemours Alfred I. Dupont Hospital for Children, Wilmington, USA. 4. Department of Orthopaedic Surgery, New York-Presbyterian Morgan Stanley's Children Hospital, Columbia University Medical Center, New York, USA. 5. Department of Orthopaedic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, USA. 6. St. Louis Children's Hospital, Department of Orthopaedic Surgery, St. Louis, USA. 7. Department of Orthopaedic Surgery, The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA, 19104, USA. anarij@email.chop.edu.
Abstract
STUDY DESIGN: Multicenter, retrospective cohort study. OBJECTIVES: Analyze the impact of MCGR proximal anchor location and density on radiographic outcomes and complications. Magnetically controlled growing rods (MCGRs) reduce the need for repeat operations for lengthening when treating spinal deformity in children. The evidence behind choosing the location and density of proximal anchors comes from the traditional growing rod and rib-based distraction technique literature. Thus, there is much debate regarding the optimal quantity and location of proximal anchors. METHODS: This study included early-onset scoliosis patients treated with MCGR with a minimum 2-year follow-up. Comparisons of 2-year correction in the coronal and sagittal planes, complication rates, and patient-reported outcomes were made based on proximal fixation type, proximal anchor density, and type of case (primary, conversion). RESULTS: This study included 155 MCGR patients. Spinal deformity correction at 2 years was significantly higher in spine-based than rib-based constructs, in terms of both the major (23.9° vs. 17.1°, p = 0.05) and minor curves (10.0° vs. 4.5°, p = 0.03). Greater proximal anchor density, regardless of location, was also associated with better major curve correction at 2 years (25.0° vs. 18.2°, p < 0.05). There was a trend towards higher risk of device migration with rib-based fixation (13.8% vs. 4.1%, p = 0.06) and rod breakage with spine-based fixation (10.3% vs. 3.4%, p = 0.21). Having 5+ proximal anchors did not significantly decrease the risk of complication, including device migration (8.4% vs. 7.7%). CONCLUSIONS: When using the MCGR, proximal spine anchors and greater anchor density impart superior deformity correction but do not significantly impact the risk of device complications. Although rib-based constructs afford less rigidity than spine-based constructs, there is a similar risk of rod breakage and device migration. This study suggests that having 5+ MCGR proximal anchors does not protect against proximal anchor complication. LEVEL OF EVIDENCE: Level III-therapeutic.
STUDY DESIGN: Multicenter, retrospective cohort study. OBJECTIVES: Analyze the impact of MCGR proximal anchor location and density on radiographic outcomes and complications. Magnetically controlled growing rods (MCGRs) reduce the need for repeat operations for lengthening when treating spinal deformity in children. The evidence behind choosing the location and density of proximal anchors comes from the traditional growing rod and rib-based distraction technique literature. Thus, there is much debate regarding the optimal quantity and location of proximal anchors. METHODS: This study included early-onset scoliosispatients treated with MCGR with a minimum 2-year follow-up. Comparisons of 2-year correction in the coronal and sagittal planes, complication rates, and patient-reported outcomes were made based on proximal fixation type, proximal anchor density, and type of case (primary, conversion). RESULTS: This study included 155 MCGR patients. Spinal deformity correction at 2 years was significantly higher in spine-based than rib-based constructs, in terms of both the major (23.9° vs. 17.1°, p = 0.05) and minor curves (10.0° vs. 4.5°, p = 0.03). Greater proximal anchor density, regardless of location, was also associated with better major curve correction at 2 years (25.0° vs. 18.2°, p < 0.05). There was a trend towards higher risk of device migration with rib-based fixation (13.8% vs. 4.1%, p = 0.06) and rod breakage with spine-based fixation (10.3% vs. 3.4%, p = 0.21). Having 5+ proximal anchors did not significantly decrease the risk of complication, including device migration (8.4% vs. 7.7%). CONCLUSIONS: When using the MCGR, proximal spine anchors and greater anchor density impart superior deformity correction but do not significantly impact the risk of device complications. Although rib-based constructs afford less rigidity than spine-based constructs, there is a similar risk of rod breakage and device migration. This study suggests that having 5+ MCGR proximal anchors does not protect against proximal anchor complication. LEVEL OF EVIDENCE: Level III-therapeutic.
Authors: Martina Tognini; Harry Hothi; Elisabetta Dal Gal; Masood Shafafy; Colin Nnadi; Stewart Tucker; Johann Henckel; Alister Hart Journal: Eur Spine J Date: 2021-03-05 Impact factor: 3.134