Mechanical complications in adult spinal deformity and the effect of restoring the spinal shapes according to the Roussouly classification: a multicentric study.

PURPOSE: To evaluate the incidence of mechanical complications in patients with adult spine deformity (ASD) treated by restoring the normal shape according to the Roussouly classification. METHODS: This is a retrospective multicentric study with a minimum follow-up of 2 years. Patients operated on with fusion for ASD (minimum performed fusion: L2 to sacrum) were included. Patients with a history of previous spinal fusion of more than three levels were excluded. Spinal and pelvic parameters were measured on the preoperative and the immediate postoperative follow-up. All mechanical complications were recorded. RESULTS: A total of 290 patients met the criteria of inclusion with a minimum follow-up of 2 years. Mechanical complications occurred in 30.4% of the cohort. The most common complication was PJK with an incidence of 18% while nonunion or instrumentation failure (rod breakage, implant failure) occurred in 12.4%. 66% of the patients were restored to the normal shape according to the Roussouly classification based on their PI and had a mechanical complication rate of 22.5%, whereas the remaining 34% of patients had a complication rate of 46.8% (p < 0.001). The relative risk for developing a mechanical complication if the algorithm was not met was 3 (CI 1.5-4.3; p < 0.001) CONCLUSION: In the recent literature, there are no clear guidelines for ASD correction. Restoring the sagittal spinal contour to the normal shapes of Roussouly according to the PI could serve as a guideline for ASD treatment. Ignoring this algorithm has a threefold risk of increased mechanical complications. We recommend this algorithm for treatment of ASD. LEVEL OF EVIDENCE: IV cross-sectional observational study. These slides can be retrieved under Electronic Supplementary Material.

Optimizing the vertical position of the brace thoracic pad: Apical rib or apical vertebra?

INTRODUCTION: The vertical position of the thoracic pad is a subject of controversy in brace design. Traditional recommendations dictate a maximal force applied at the level of the apical rib, about 2 levels below the apical vertebra. We sought to evaluate the optimal vertical position of the brace thoracic pad using fulcrum bending radiographs. HYPOTHESIS: A lateral force applied at the apical vertebra of a thoracic curve is more efficient at correcting coronal deformity than a force placed the apical rib. PATIENTS AND METHODS: In this prospective study, we recruited patients presenting with adolescent idiopathic scoliosis (AIS) and Risser stage 0-2 over a period of 12 months. Patients with a history of spine or thoracic surgery were excluded. Two fulcrum bending radiographs were performed for each patient: one with the center of the fulcrum placed under the most lateral part of the apical rib and another with the fulcrum centered below the apical vertebra. Cobb angles were measured on each fulcrum radiograph and compared using a paired t test. RESULTS: Fifty-two patients were included, with a mean age of 12.4 years and mean thoracic Cobb angle of 39.4˚. Placing a fulcrum under the apical vertebra reduced the Cobb angle to a mean of 11.5˚, which was significantly lower than a fulcrum placed under the apical rib (14.3˚, p=0.001). This corresponded to a 20% relative loss in the absolute correction angle when placing the fulcrum under the apical rib. The difference between the 2 Cobb angles was not significantly correlated to patient age (p=0.896) or curve apex (p=0.813). DISCUSSION: This is the first clinical study addressing the vertical position of the thoracic pad in braces for AIS. A lateral force applied at the level of the apical vertebra was significantly more efficient at reducing thoracic curve deformities than one applied at the apical rib. Our results provide clinical support to finite element studies that refute traditional recommendations of brace design, advocating for a revision of these guidelines to optimize non-operative treatment of AIS. LEVEL OF EVIDENCE: II, prospective comparative study.

Pediatric cervical spine instability.

Cervical spine instability in children is rare but not exceptional and may be due to many factors. Although it mostly occurs at the upper cervical spine, all vertebrae from the occiput to T1 may be involved. It may be acute or chronic, occurring secondary to trauma or due to congenital anomaly, skeletal or metabolic dystrophy or rheumatoid arthritis. It can be isolated or associated with other musculoskeletal or visceral anomalies. A thorough knowledge of embryology, anatomy, physiology and physiopathology of the cervical spine in children is essential to avoid pitfalls, recognize normal variants and identify children at risk of developing cervical spine instability and undertake the appropriate treatment.