The metabolic basis of adolescent idiopathic scoliosis: 2011 report of the “metabolic” workgroup of the Fondation Yves Cotrel

OBJECTIVE: The purpose of this review is to elucidate the metabolic processes involved in the pathogenesis of adolescent idiopathic scoliosis (AIS) in light of research by the present authors as well as current literature. METHODS: Pathogenetic mechanism

Is decreased bone mineral density associated with development of scoliosis? A bipedal osteopenic rat model

<p>Abstract</p> <p>Background</p> <p>An association between adolescent idiopathic scoliosis and osteopenia has been proposed to exist. It is still not clear whether there is such an association and if so, whether osteopenia is a causative factor or a consequence. Our previous pilot studies have suggested the presence of osteopenia in scoliotic animals. The aim of this study was to investigate the development of scoliosis in an unpinealectomized bipedal osteopenic rat model, implementing osteoporosis as a causative factor.</p> <p>Methods</p> <p>Fifty Sprague-Dawley rats were rendered bipedal at the 3^rdpostnatal week and separated into control (25 rats) and heparin (25 rats receiving 1 IU/gr body weight/day) groups. DEXA scans after 4 weeks of heparin administration showed low bone mass in the heparin group. Anteroposterior and lateral x-rays of the surviving 42 animals (19 in heparin and 23 in control groups) were taken under anesthesia at the 40^thweek to evaluate for spinal deformity. Additional histomorphometric analysis was done on spine specimens to confirm the low bone mass in heparin receiving animals. Results of the DEXA scans, histomorphometric analysis and radiological data were compared between the groups.</p> <p>Results</p> <p>Bone mineral densities of rats in the heparin group were significantly lower than the control group as evidenced by both the DEXA scans and histomorphometric analyses. However, the incidence of scoliosis (82% in heparin and 65% in control; p > 0.05) as well as the curve magnitudes (12.1 ± 3.8 in heparin versus 10.1 ± 4.3 degrees in control; p > 0.05) were not significantly different. Osteopenic rats were significantly less kyphotic compared to control specimens (p = 0.001).</p> <p>Conclusions</p> <p>This study has revealed two important findings. One is that bipedality (in the absence of pinealectomy) by itself may be a cause of scoliosis in this animal model. Further studies on animal models need to consider bipedality as an independent factor. Secondly, relative hypokyphosis in osteopenic animals may have important implications. The absence of sagittal plane analyses in previous studies makes comparison impossible, but nonetheless these findings suggest that osteopenia may be important in the development of 3D deformity in adolescent idiopathic scoliosis.</p

Repair, regenerative and supportive therapies of the annulus fibrosus: achievements and challenges

Lumbar discectomy is a very effective therapy for neurological decompression in patients suffering from sciatica due to hernia nuclei pulposus. However, high recurrence rates and persisting post-operative low back pain in these patients require serious attention. In the past decade, tissue engineering strategies have been developed mainly targeted to the regeneration of the nucleus pulposus (NP) of the intervertebral disc. Accompanying techniques that deal with the damaged annulus fibrous are now increasingly recognised as mandatory in order to prevent re-herniation to increase the potential of NP repair and to confine NP replacement therapies. In the current review, the requirements, achievements and challenges in this quickly emerging field of research are discussed

Correction of rotational deformity and restoration of thoracic kyphosis are inversely related in posterior surgery for adolescent idiopathic scoliosis

Adolescent Idiopathic Scoliosis (AIS) is a complex three dimensional deformity the treatment of which remains to be surgical correction of the deformity as it had progressed over certain thresholds. The main focus in surgical treatment had, for decades, been the amount of correction in the coronal plane whereas corrections in sagittal and rotational (axial) planes have also been recognized as almost as important as the coronal over the recent decades. The hypotheses presented and discussed in this study is the virtual adversity between the rates of correction in these two (sagittal and axial) planes. Namely, we are suggesting that due to an elongated anterior spinal column as an intrinsic component of AIS, posterior surgery cannot correct both the axial plane deformity and the thoracic hypokyphosis in the sagittal plane at the same time, unless the posterior spinal column is substantially lengthened. This hypothesis is supported by 3D modeling of the AIS spine as well as the relative inability in changing the sagittal alignment of the thoracic spine demonstrated by a literature search by us. Understanding and internalization of this hypothesis by AIS surgeons is important as it suggests that by posterior instrumentation, unless a riskier approach of substantially lengthening the spinal column is taken, surgeons need to make the choice of correcting the hypokyphosis OR axial rotation

Correction of rotational deformity and restoration of thoracic kyphosis are inversely related in posterior surgery for adolescent idiopathic scoliosis

Adolescent Idiopathic Scoliosis (AIS) is a complex three dimensional deformity the treatment of which remains to be surgical correction of the deformity as it had progressed over certain thresholds. The main focus in surgical treatment had, for decades, been the amount of correction in the coronal plane whereas corrections in sagittal and rotational (axial) planes have also been recognized as almost as important as the coronal over the recent decades. The hypotheses presented and discussed in this study is the virtual adversity between the rates of correction in these two (sagittal and axial) planes. Namely, we are suggesting that due to an elongated anterior spinal column as an intrinsic component of AIS, posterior surgery cannot correct both the axial plane deformity and the thoracic hypokyphosis in the sagittal plane at the same time, unless the posterior spinal column is substantially lengthened. This hypothesis is supported by 3D modeling of the AIS spine as well as the relative inability in changing the sagittal alignment of the thoracic spine demonstrated by a literature search by us. Understanding and internalization of this hypothesis by AIS surgeons is important as it suggests that by posterior instrumentation, unless a riskier approach of substantially lengthening the spinal column is taken, surgeons need to make the choice of correcting the hypokyphosis OR axial rotation

The Effect of Transpedicular Intracorporeal Grafting in the Treatment of Thoracolumbar Burst Fractures on Canal Remodeling

Short-segment posterior instrumentation for the treatment of thoracolumbar burst fractures has been reported with a high rate of failure. Transpedicular intracorporeal grafting in combination with short-segment instrumentation has been offered as an alternative to prevent failure. However, concern still remains about the potential complication of further canal narrowing or failure of remodeling with this technique. The purpose of this prospective, randomized, controlled study is to evaluate the effect of transpedicular intracorporeal grafting on spinal canal restoration and remodeling in a group of patients treated with short-segment instrumentation for thoracolumbar burst fractures. Twenty-one patients with thoracolumbar burst fractures were randomised into transpedicular grafting (TPG) (n=11) and non-transpedicular grafting (NTPG) (n=10) groups, and were prospectively followed for an average of 50 months (range 25-85 months). Groups were similar in age, type of fracture, load sharing classification and kyphotic deformity. Preoperative, postoperative and follow-up computed tomographic (CT) images through the level of pedicles were obtained, corrected for differences in magnification, and digitized. Areas of the spinal canals were measured and normalized by the estimated area at that level (average of adjacent levels). Average kyphosis was 19.7degrees+/-6.2degrees at presentation, was corrected to 1.9degrees+/-4.9degrees by operation, but was found to have deteriorated to 9.1degrees+/-6.4degrees at final follow-up. There were no differences between groups regarding the evolution of sagittal deformity. Spinal canal narrowing was 38.5+/-18.2% at presentation, 22.1+/-19.8% postoperatively, and it further improved to -2.5+/-16.7% at follow-up, similar for both groups. Our results demonstrate that transpedicular intracorporeal grafting in the treatment of burst fractures does not have a detectable effect on the rate of reconstruction of the canal area or on remodeling. Spinal canal remodeling was observed to occur in all patients regardless of grafting.Wo

The sensitivity and specificity of 0.5% apraclonidine in the diagnosis of oculosympathetic paresis

Aims: To evaluate the sensitivity and specificity of 0.5% apraclonidine test in the diagnosis of oculosympathetic paresis (OSP). Method: Apraclonidine (0.5%) was administered to 31 eyes, nine with a diagnosis of Horner syndrome (HS), 22 with bilateral OSP caused by diabetes, and to 54 control eyes. All were confirmed with the cocaine test. The effects on pupil diameter and upper eyelid level were observed 1 hour later. Results: Apraclonidine caused a mean dilation of 2.04 mm (range 1–4.5) (p<0.001) in the pupils with OSP and it caused pupillary constriction in the control eyes with a mean change of −0.14 mm (range 0.5 to −1) (p<0.05). It caused reversal of anisocoria in all HS cases. Its effects on both pupil diameters and upper lid levels differed significantly between the groups (p<0.001). The mean elevation in the upper lid was 1.75 mm (range 1–4) in the OSP group (p<0.001) and 0.61 mm (range 0–3) in the control group (p<0.001). Conclusion: The effect of the apraclonidine (0.5%) test on the pupil diameter was diagnostic for OSP and had at least the same sensitivity and specificity as the cocaine test for the diagnosis of OSP

The effect of anterior spinal fusion on spinal canal development in an immature porcine model

PubMedID: 19564754STUDY DESIGN.: Experimental study. OBJECTIVE.: To investigate whether anterior spine fusion in the immature porcine spine has an adverse effect on the development of spinal canal. SUMMARY OF BACKGROUND DATA.: Neurocentral cartilage (NCC) is located in the posterior vertebral body and responsible for the development of posterior aspect of the spinal canal. Injury to the NCC interferes with the development of the spinal canal. METHODS.: Twelve 8-week-old domestic pigs were used to develop an anterior fusion model. A standard procedure as L3-L4, L4-L5 discectomy, and L3-L5 anterior instrumented spine fusion was performed. To evaluate the development of the spinal canal, all subjects had computed tomography scans before the procedure and at the final follow-up. The spinal canal area was measured at the control level (CL) (L2), arthrodesis level (AL) (L4), superior (L3), and inferior (L5) instrumented level (SIL and IIL). Percent change in spinal canal area from before surgery to final follow-up was also calculated. RESULTS.: Eleven subjects were available for the study. All subjects developed local kyphosis over the fused segments. The average area of L2 (CL) was 0.56 ± 0.06 cm before surgery. The average areas of the L3 (SIL), L4 (AL), and L5 (IIL) were 0.62, 0.70, and 0.77 cm, respectively. At the final follow-up the average area of L2 was 1.20 cm. The average areas of the SIL, AL, and IIL were 1.16, 1.19, and 1.33 cm, respectively. The percent increase in spinal canal area at the CL was 116.6% whereas it was 85.8%, 71.0%, and 71.2% at SIL, AL, and IIL, respectively. CONCLUSION.: Anterior spinal arthrodesis in the immature porcine spine results in iatrogenic retardation on spinal canal growth. This effect is most likely related to the tethering effect of the interbody fusion over the NCC. Although, it is difficult to directly extrapolate these findings to clinical practice, the spine surgeons operating on pediatric patients should be aware of this possibility. © 2009 Lippincott Williams & Wilkins, Inc

The effect of posterior distraction on vertebral growth in immature Pigs: An experimental simulation of growing rod technique

PubMedID: 20195208STUDY DESIGN.: Experimental study. OBJECTIVE.: The aim of this study is to evaluate the vertebral body growth under distraction forces in immature pigs treated with growing rod (GR) technique. SUMMARY OF BACKGROUND DATA.: Distraction forces applied on growth plate of appendicular skeleton stimulate longitudinal growth. However, the effect of distraction forces on axial skeletal growth has not been fully investigated yet. METHODS.: Twelve 10-week-old domestic pigs were used in this experimental model to simulate GR technique. Four of them were lost during postoperative period because of deep wound infection. Cranially T12-L1 and caudally L4-L5 vertebrae were instrumented by pedicle screws bilaterally, while L2 and L3 were skipped. Distraction between pedicle screws was applied at index surgery. The rods were then lengthened twice in a month interval. All subjects were evaluated with anteroposterior and lateral spinal radiograph before surgery, after surgery, and at the final follow-up. The vertebral body heights of distracted segments (HD = L2 and L3) and control segments (HC = T9, T10 and T11) were measured. Average vertebral body heights and the increase percentage in the vertebral body heights were compared among control segments and distracted segments. RESULTS.: The preoperative vertebral body height was similar in 2 groups (preHC: 10.81 mm, n = 19, preHD: 11.27 mm, n = 16, P > 0.05). At the final follow-up, the average vertebral body height in distraction group was significantly higher than the control group (postHC: 17.03 mm, postHD: 18.58 mm, P < 0.05). The increase percentage in vertebral body height was higher in distracted segments, but there was no statistically significant difference between the 2 groups. CONCLUSION.: The vertebral growth continues during GR instrumentation. Distraction forces might stimulate also apophyseal growth of axial skeleton. © 2010, Lippincott Williams & Wilkins