Background: To compare the routine use of posterior-based (Ponte) osteotomies to complete inferior facetectomies in thoracic idiopathic scoliosis. Hypokyphosis is common in thoracic adolescent idiopathic scoliosis. The use of pedicle screw fixation in deformity correction can exacerbate this hypokyphosis. We hypothesized that by utilizing posterior-based Ponte osteotomies rather than facetectomies, we could improve coronal plane correction and decrease the loss of kyphosis during curve correction. Methods: The radiographs and clinical charts of patients with idiopathic scoliosis (Lenke types I, II) who underwent isolated thoracic posterior spinal fusion utilizing primarily pedicle screw constructs from January 2008 to August 2010 were reviewed. Maximum preoperative Cobb angle, thoracic kyphosis (T5-T12), levels instrumented, number of posterior-based osteotomies, operative time, estimated blood loss, and postoperative residual coronal Cobb angle and kyphosis were recorded. Operative time per level, blood loss per level, percent main curve correction, and change in thoracic kyphosis was calculated. Patients having undergone complete inferior facetectomies and those with multilevel Ponte osteotomies were then compared. Results: Eighteen patients underwent posterior spinal fusion with osteotomies and 19 patients had complete inferior facetectomies during this time period. The osteotomy cohort had a larger preoperative Cobb angle [59±10 vs. 52±8 (mean±SD); P=0.03]. No difference was observed in the preoperative kyphosis (22±15 vs. 25±12) or in levels fused (9±1 vs. 8±1). Patients with routine osteotomies had them performed at 76% of the levels instrumented. No significant difference was found in terms of percentage of coronal plane correction (84% in both groups), average postoperative kyphosis 28±8 versus 25±7, or the change in kyphosis 6±14 versus 0±2 degrees, in the osteotomy and the facetectomy groups, respectively. Estimated blood loss per level was significantly higher in the osteotomy group (97±42 mL vs. 66±25 mL; P=0.01) as was time per level 31±5 versus 23±3 minutes/level (P<0.001). Conclusions: This study shows a significantly higher blood loss and operative time associated with the use of routine posterior osteotomies in the thoracic spine without a significant improvement in coronal or sagittal correction.

Background: Respiratory weakness and spinal deformity are common in patients with spinal muscular atrophy (SMA). Posterior (distraction type) growing rods have recently gained favor as a treatment option in this population, due to their ability to prevent spinal deformity progression and their potential to allow lung volumes to increase over time. The objective of this study was to determine the impact of posterior growing rods on the spinal alignment and respiratory function in children with SMA with intermediate term follow-up. Methods: A single center, retrospective review was performed on SMA patients treated with growing rods, inserted between 2004 and 2010, with a minimum of 2-year follow-up. SMA type, changes in the route of bi-level positive airway pressure respiratory support and the amount of time receiving respiratory support are reported. Pulmonary function tests (PFTs) and radiographs were reviewed and data evaluated preinsertion, postinsertion, and at latest follow-up. Results: Sixteen children with SMA (5 type I, 11 type II) met inclusion criteria. The average age of insertion was 5.8 (±1.5) years, the median number of lengthenings was 4 (range, 3 to 5), and the median time between insertion and last clinical review was 4.7 (range, 2.7 to 9.5) years. Radiographic review demonstrated significant (P<0.05) improvements in the following: Spinal curve magnitude, pelvic obliquity, space available for the lung, rib vertebral angle difference, and thoracic kyphosis following growing rod implantation. Thoracic and lumbar height and chest width and depth increased significantly (P<0.05) over the lengthening process. None of the patients initially required more than noninvasive positive pressure ventilation support. Fifteen of the 16 experienced no changes in their noninvasive positive pressure ventilation support needs throughout the study duration, requiring support only at night and naps. Serial PFTs were available for 6 children with SMA type II. PFTs demonstrated significant improvements in absolute forced vital capacity (FVC), minimal changes in the maximal inspiratory and expiratory pressures, and a gradual worsening of percent predicted FVC. Conclusions: Clinical respiratory support requirements appear to stabilize following the insertion and lengthening of posterior based growing rods in the SMA population. Similar to previous studies, increased spinal height and thoracic cavity size were noted throughout the process. Despite an increasing absolute FVC, the percent predicted FVC diminished over time. Level of Evidence: Level IV—therapeutic.

Background: The purpose of this study was to explore the role of perinatal vitamin-D intake on the development and characterization of hyperkyphosis in a porcine model. Methods: The spines of 16 pigs were assessed at 9, 13, and 17 weeks of age with radiography and at 17 weeks with computed tomography (CT), magnetic resonance imaging (MRI), histology, and bone-density testing. An additional 169 pigs exposed to 1 of 3 maternal dietary vitamin-D levels from conception through the entire lactation period were fed 1 of 4 nursery diets supplying different levels of vitamin D, calcium, and phosphorus. When the animals were 13 weeks of age, upright lateral spinal radiography was performed with use of a custom porcine lift and sagittal Cobb angles were measured in triplicate to determine the degree of kyphosis in each pig. Results: The experimental animals had significantly greater kyphotic sagittal Cobb angles at all time points when compared with the control animals. These hyperkyphotic deformities demonstrated no significant differences in Hounsfield units, contained a slightly lower ash content (46.7% ± 1.1% compared with 50.9% ± 1.6%; p < 0.001), and demonstrated more physeal irregularities. Linear mixed model analysis of the measured kyphosis demonstrated that maternal diet had a greater effect on sagittal Cobb angle than did nursery diet and that postnatal supplementation did not completely eliminate the risk of hyperkyphosis. Conclusions: Maternal diets deficient in vitamin D increased the development of hyperkyphosis in offspring in this model. Clinical Relevance: This study demonstrates that decreased maternal dietary vitamin-D intake during pregnancy increases the risk of spinal deformity in offspring. In addition, these data show the feasibility of generating a large-animal spinal-deformity model through dietary manipulation alone.

Purpose: The aim of this study was two-fold: (1) to determine if radiographic measures can be reliably made in infants being treated with the Ponseti method and (2) to document radiographic changes before and after Achilles tenotomy. Methods: A retrospective radiographic and chart review was performed on children with clubfoot treated by the Ponseti method at a single institution over a 10-year period. Five independent reviewers measured a series of angles from a lateral forced dorsiflexion radiograph taken prior to and following Achilles tenotomy. These measures were taken in triplicate to determine the intra- and inter-reader reliability of dorsiflexion, tibio-calcaneal, talo-calcaneal, and talo-first metatarsal angles. Results: Thirty-six subjects (56 feet) were treated with the Ponseti method and met the inclusion criteria. The median (range) age of patients at the time of tenotomy was 52 (34–147) days. The intra-reader reliability [intra-rater correlation coefficient (ICC)] for each of the measured angles pre- and post-tenotomy ranged from 0.933 to 0.995 and 0.864 to 0.995, respectively. Similarly, the inter-reader reliabilities (ICC) ranged from 0.727 for the pre-tenotomy (talo-calcaneal) to 0.950 for the post-tenotomy (talo-first metatarsal) angles. The mean differences between pre- and post-tenotomy radiographs were: dorsiflexion increase of 17°, tibio-calcaneal angle increase of 19°, talo-calcaneal angle increase of 9°, and talo-first metatarsal angle increase of 10° ( p-value ≤0.001 for all measurements except the talo-first metatarsal angle, with a p-value of 0.001). Conclusions: Reliable radiographic measures can be made from lateral dorsiflexion radiographs of clubfeet treated with the Ponseti method before and after Achilles tenotomy.