During the last decade or more, the anchors used for instrumentation in scoliosis surgery are predominantly transpedicular screws, according to Suk. The long term radiographical feature of screw fixation after scoliosis surgery is not previously studied. A consecutive series of 81 cases with AIS operated on with an all screw construct has been studied by means of low dose CT postoperatively and at 2 years postoperatively. There were 67 females and 14 males, with a mean age of 18.3 ± 3 years. In 26 / 81 (32 %) there were signs of loosing of one or more screws, at a maximum 3 screws. We observed loosened screws in the upper thoracic region in 16 cases, in the thoracolumbar 6 and in lumbar area in 4. Mean pre-op Cobb angle was 56 in cases of loosening and 53 of intact screw fixation (n.s.), the correction rate was 69% in loosened vs 70% among intact screws (n.s.). In males there were signs of loosening in 8/14 (57%) and in females 18/67 (27%). Among cases with loosening, 14% had suboptimal screw positioning postoperatively, in intact cases it was observed in 11% (n.s.). In the whole group there were signs of suboptimal screw positioning 12%. Clinically, 1 case had a loosened L4 screw replaced; and at all 21/26 had no complaints and 5/26 reported minor pain or discomfort. 1/26 had a minor proximal junctional kyphosis about 10°, in 3/26 there was a pull-out of some few mms. With plain radiography loosening could be observed in 11/26 cases; 5 were in the lumbar region. In a consecutive series of 81 adolescents with idiopathic scoliosis who had underwent scoliosis surgery according to Suk, one third showed, 2 years after the intervention, some minor screw loosening, assessed by low dose CT. One patient had one lumbar screw replaced and only 5 patients reported minor discomfort. Males were more prone to develop screw loosening

Aims

The aim of this study was to assess the accuracy of pedicle screw placement, as well as intraoperative factors, radiation exposure, and complication rates in adult patients with degenerative disorders of the thoracic and lumbar spines who have undergone robotic-navigated spinal surgery using a contemporary system.

The purpose of this study is to investigate what effect cross links have on scoliosis constructs and whether cross links may be used instead of pedicle screws at the apex of the deformity. The rotational stiffness of six different construct designs was investigated on scoliotic sawbone models with zero, one or two cross links. In three of the constructs the screws at the apex were removed. Testing was performed to an average torque of 3Nm and ration was detected using electromagnetic motion tracking system. The stiffness in axial rotation of all constructs increased with the number of cross links, however the difference was not statistically significant. In constructs with apical screws the stiffness increased by 3.01% and 12.9% for one and two cross links respectively. In constructs without apical screws the increase was 1.64% and 14.3% for one and two cross links respectively. The total stiffness of the construct increased with the addition of apical screws by 20%, 21.7% and 18.8% for zero, one and two cross links respectively. This increase was statistically significant using a paired t-test (p= 0.01142). On the basis of these results we conclude that the use of cross links in scoliosis correction surgery is not necessary. Pedicle screws positioned at the apex of the scoliosis curve statistically increase the stiffness in axial rotation and are therefore necessary to promote an environment suitable for bony fusion

Pedicle screws as the principal anchors of instrumentation in correction of scoliosis as described by Suk 15 years ago have now gained a wide acceptance among deformity surgeons. Pedicles in the concavity of the major as well as compensatory curves are often dysplastic making screw placement occasionally problematic. In cases of dural ectasia with dystrophic pedicles, the transpedicular screw anchorage is sometimes impossible. In 2009 Gardner et al. presented a case of NF-1 with a troublesome cervico-thoracic kyphosis where they created distal anchors by means of laminar screw fixation. In the presentation of this case, the idea is further developed. Case. A 14 year old girl without any obvious syndromic feature underwent surgery for a 70 degree thoracic scoliosis. A preoperatively MRI showed a dural ectasia. A preoperative low dose–CT revealed dystrophic pedicles from Th4 to L4, making transpedicular screw placement problematical. The operation was performed with the aid of an O-arm. At all levels from Th2 – L2 laminar screw fixation was used. Postoperatively, low-dose CT showed excellent screw positioning with the exceptiuon of one proximal screw which compromised a foramem but, without any symptoms. The postoperative course was quite uneventful and the patient was discharged at day 5days postoperatively. The correction rate was 70%. Conclusion. In cases of scoliosis with severe dystrophic pedicles, the use of laminar screws is a good alternative to problematic transpedicular screw placement

To describe a modification of the existing technique for C2 translaminar screw fixation that can be used for salvage in difficult cases. Bilateral crossing C2 laminar screws have recently become popular as an alternative technique for C2 fixation. This technique is particularly useful in patients with anomalous anatomy, as a salvage technique where other modes of fixation have failed or as a primary procedure. However, reported disadvantages of this technique include breach of the dorsal lamina and spinal canal, early hardware failure and difficulty in bone graft placement due to the position of the polyaxial screw heads. To address some of these issues, a modified technique is described. In this technique, the upper part of the spinous process of C2 is removed and the entry point of the screw is in the base of this removed spinous process. From October 2008 to March 2009, 6 patients underwent insertion of unilateral translaminar screws using our technique. The indications were: basilar invagination(three cases), C1/C2 fracture (two cases), tumour (one case). Age varied from 22 to 81 years (mean 48 years). All patients had post-operative x-ray and CT scan to assess position of the screws. Mean follow-up was 6 months. The screw position was satisfactory in all patients. There were no intraoperative or early postoperative complications. Our modification enables placement of bone graft on the C2 lamina and is also less likely to cause inadvertent cortical breach. Because of these advantages, it is especially suitable for patients with advanced rheumatoid arthritis with destruction of the lateral masses of C2 or as part of a hybrid construct in patients with unilateral high riding vertebral artery. This technique is not suitable for bilateral translaminar screw placement

Introduction. The change of position of the distal pedicle screws with growing rods in relation to vertebral bodies was described as pedicle screws migration. Pedicle screws are subjected to serial distractive forces pushing them down with every distraction; additionally there is continuous growth of the vertebral bodies during the treatment period. These two factors can affect the change of position of the pedicle screws in relation to the vertebrae during the use of growing rods. To our knowledge, this finding has never been studied, confirmed, or quantified. Methods. This is a retrospective review of the radiographs and operative notes of 23 consecutive cases of early-onset scoliosis treated with single growing rods. Age at index surgery ranged from 4 years 2 months to 8 years 9 months, and the number of distractions was four to 11 per patient. Measurements were done on post-index and latest follow-up true lateral radiographs. With optimum initial position of the screws in the pedicle, we calculated the distance between the upper end plate and the pedicle screw (distance superior to the screw [SS]) and the distance between the screw and lower-end plate (distance inferior to the screw [IS]). We expressed this ratio as a percentage: SS/IS x 100%. Any increase in this percentage with time denoted a more caudal position; however, a change in the percentage of less than 10% was regarded as insignificant. Results. Seven cases were excluded because of inadequate radiographs for measurements. Within the distal construct, measurements of the upper pedicle screw showed that six cases had a change of less than 10% and were regarded as insignificant. Ten cases had changes of more than 10%, five had changes between 10% and 50%, three between 50% and 100%, and two more than 100%. We identified two types of migration: the first within the pedicle with pedicle elongation, and the second through and distal to the pedicle. None of the patients had adverse clinical consequences related to this change. Conclusions. Change of screw position with time is a frequent occurrence in the distal pedicle screws with single growing rods. Two different types were identified. With growing rods some degree of distal pedicle screw migration in this paediatric age group may not be regarded as a complication of treatment

Introduction. There is an unresolved controversy in the published work about the effect of screws crossing the neuro-central cartilage (NCC) on spinal canal dimension in very young children and in animals. Anterior vertebral body screws with fusion can invade and damage the NCC, especially at the site of screw insertion; however, this finding has never been studied. Methods. This study is a retrospective, clinical and radiological analysis of seven consecutive children aged 1–2 years treated with anterior vertebral instrumentation and fusion by downsized rod screw systems. The mean age at time of surgery was 2 years 4 months (range 1 year 9 months to 2 years 10 months). The average follow-up period was 3 years 3 months (2 years 6 months to 4 years 5 months). 16 screws inserted anteriorely were evaluated by a follow-up CT scan. Spinal canals were divided with known anatomical landmarks into right and left hemicanals. The relation of the anterior screws to the NCC and the spinal canal dimension were studied. All clinical and radiological complications were recorded. Results. Only 11 screws were suitable for measurement. There was a difference of 10–20% between the surface areas of the two hemicanals in six levels in which the screw heads were passing through or encroaching on the NCC; the canal was smaller ipsilateral to the affected NCC. The hemicanals were almost symmetrical in five levels in which the screw heads were away from the NCC, except in one in which it was touching the NCC. For the 16 screws evaluated there were no recorded complications apart from one screw breaching the adjacent end plate. Conclusions. Anterior vertebral body screws with fusion can encroach on the NCC when inserted in very young children, which seems to decrease the ipsilateral canal dimension between 10% and 20%. Apart from this finding, anterior instrumentation is safe when used in very young children aged 1–2 years. Canal asymmetry had no clinical effect in childhood; however, long-term follow-up of these children is needed to measure its clinical significance. Change of screw position with time is a frequent occurrence in the distal pedicle screws with single growing rods. There are two different types identified. With growing rods some degree of distal pedicle screw migration in this paediatric age group may not be regarded as a complication of treatment

Objective. The use of all pedicle screw constructs for the management of spinal deformities has gained widespread popularity. However, the placement of pedicle screws in the deformed spine poses unique challenges for the spinal surgeon. The purpose of this study was to evaluate the complications and radiological outcomes of surgery in 124 consecutive patients with spinal deformity. These patients underwent correction of coronal and sagittal imbalance with segmental pedicle screw fixation only. Background. All pedicle screw constructs have been associated with improved correction in all three planes. In patients with severe deformity, such constructs can obviate the need for anterior surgeries, and the higher implant cost is offset by the avoidance of dual anterior and posterior approaches. Pedicle screw fixation enables enhanced correction of spinal deformities, but the technique is still not widely applied for thoracic deformities for fear of neurological complications. This is a retrospective study that was carried out on 124 patients who underwent segmental screw fixation for coronal and sagittal spinal deformities. The purpose of this study was to evaluate the complications and outcomes of this technique and also assess the evidence of enhanced correction. Material and Methods. A total of 124 consecutive patients subjected to pedicle screw fixation for spinal deformities were analysed after a minimum period of follow-up of two years. Etiologic diagnoses were idiopathic scoliosis in 32, neuromuscular scoliosis 48, Scheuermann's kyphosis in 28 and others 16. They were reviewed using the medical records and preoperative, intraoperative and postoperative radiographs. Computed tomography was performed when screw position was questionable. Deformity correction was determined on preoperative and postoperative radiographs. The positions of the screws were evaluated using intraoperative and postoperative radiographs. There were 51 male and 73 female patients with the mean age of 17.2 years (range, 10-25 years). The average cobb angle for scoliosis and kyphosis were 55°(range 45°-85°) and 72° (range 68°-100°) respectively. Results. A total of 2784 pedicle screws were inserted and 1488 screws were inserted in the thoracic spine (18 screws/patient). Screw-related neurological complications occurred in two patients 0.4%; these comprised a transient paraparesis and dural tear. Other complications comprised six intraoperative pedicle fractures, 12 screw loosening, four postoperative infections and one haemothorax. There were no significant screw-related neurological or visceral complications. The average correction was 78% for scoliosis and 51% for kyphosis. The mean estimated blood loss was 653 ml (range, 510-850), the mean operation time was 148 minutes (range, 120-220). Conclusion. We were able to demonstrate that application of pedicle screw construct is safe and advantageous in the management of spinal deformities. Significant correction has been achieved with a single stage posterior surgery in all groups. Scoliosis and kyphotic deformity corrections were 78% and 51% respectively; this is far superior to correction achieved with one stage surgery with other constructs. This study showed that improved derotation has decreased the need for thoracoplasty, thus eliminating its risk of associated morbidity. Superior control of the deformity obviated the need for an anterior approach in severe curves. Improved correction, lower morbidity and shorter hospitalisation has compensated for higher implant cost. We believe using all pedicle screw fixation is a relatively safe procedure and offers an excellent correction. This correction was maintained throughout the follow up period. Despite our safety record in thoracic pedicle screw placement, we believe this technique can be potentially dangerous in inexperienced hands, and requires a long learning curve. Therefore, a thorough anatomical knowledge of pedicle morphology, a detailed analysis of pre-operative imaging coupled with experience is essential to avoid complications. Ethics approval None. Interest Statement None

Aims

The aim of this study was to systematically compare the safety and accuracy of robot-assisted (RA) technique with conventional freehand with/without fluoroscopy-assisted (CT) pedicle screw insertion for spine disease.

Aims

To report the mid-term results of a modified self-growing rod (SGR) technique for the treatment of idiopathic and neuromuscular early-onset scoliosis (EOS).

With the identification of literature shortfalls on the techniques employed in intraoperative navigated (ION) spinal surgery, we outline a number of measures which have been synthesised into a coherent operative technique. These include positioning, dissection, management of the reference frame, the grip, the angle of attack, the drill, the template, the pedicle screw, the wire, and navigated intrathecal analgesia. Optimizing techniques to improve accuracy allow an overall reduction of the repetition of the surgical steps with its associated productivity benefits including time, cost, radiation, and safety.

Cite this article: Bone Joint J 2020;102-B(3):371–375.

Aims

We aimed to retrospectively assess the accuracy and safety of CT navigated pedicle screws and to compare accuracy in the cervical and thoracic spine (C2-T8) with (COMB) and without (POST) prior anterior surgery (anterior cervical discectomy or corpectomy and fusion with ventral plating: ACDF/ACCF).

Objectives

To employ a simple and fast method to evaluate those patients with neurological deficits and misplaced screws in relatively safe lumbosacral spine, and to determine if it is necessary to undertake revision surgery.

Objectives

Cement augmentation of pedicle screws could be used to improve screw stability, especially in osteoporotic vertebrae. However, little is known concerning the influence of different screw types and amount of cement applied. Therefore, the aim of this biomechanical in vitro study was to evaluate the effect of cement augmentation on the screw pull-out force in osteoporotic vertebrae, comparing different pedicle screws (solid and fenestrated) and cement volumes (0 mL, 1 mL or 3 mL).

We reviewed 212 consecutive patients with adolescent idiopathic scoliosis who underwent posterior spinal arthrodesis using all pedicle screw instrumentation in terms of clinical, radiological and Scoliosis Research Society (SRS)-22 outcomes. In Group 1 (51 patients), the correction was performed over two rods using bilateral segmental pedicle screws. In Group 2 (161 patients), the correction was performed over one rod using unilateral segmental pedicle screws with the second ^{rod providing stability of the construct through two-level screw fixation at proximal and distal ends. The mean age at surgery was 14.8 years in both groups. Comparison between groups showed no significant differences with regard to age and Risser grade at surgery, pre- and post-operative scoliosis angle, coronal Cobb correction, length of hospital stay and SRS scores. Correction of upper thoracic curves was significantly better in Group 1 (p = 0.02). Increased surgical time and intra-operative blood loss was recorded in Group 1 (p < 0.001 and p = 0.04, respectively). The implant cost was reduced by mean 35% in Group 2 due to the lesser number of pedicle screws.}

Unilateral and bilateral pedicle screw techniques have both achieved excellent deformity correction in adolescent patients with idiopathic scoliosis, which was maintained at two-year follow-up. This has been associated with high patient satisfaction and low complication rates.