Universal Clamps Research Articles

Experimental research procedure of roller forming unit

Experimental research is conducted followed by a comparative analysis of the results, which are obtained in the process of theoretical and experimental studies, to check the theoretical research adequacy of the roller forming unit with the crank drive.
 We have developed the experimental research program for the roller forming unit with the crank drive. The research stand of roller forming with the crank drive was used for experimental studies. This research stand allows you to carry out full-value experimental studies on the determination of dynamic loads unrestricted. The experimental research program provides the determination of the interaction force for the compaction roller with the construction mixture, the force in the unit connecting rod, the torque on the unit drive shaft and the power, which is necessary for the realization of the forming process. The determination of these loads will make it possible to realistically assess the condition of the forming unit and rationally carry out its design and operation.
 Plan, procedure and processing of experimental research data have been developed. The measuring and recording equipment were selected to determine the force loads of the research stand for conducting experimental studies, which transforms the received numerical data into Microsoft Excel for their processing. The measurement of the force in the connecting rod and the interaction vertical force of the compaction roller with the construction mixture was carried out using strain gauges. These are pasted according to the bridge scheme on the connecting rod and the metal plate, which is located in the form with the building mixture under the compaction roller. RK 435 universal clamps, which make it possible to measure the line voltage, the current strength and the power under unit different load modes, are used to measure the power required for the forming process.

Spine surgery in children: past, present and future

In accordance with almost 55 years of experience in pediatric spine surgery, it is easy for me to describe the evolution of surgical technique, as well as indications for surgical interventions that were initially performed without the use of any instrumentation (which now are still occasionally considered as useful) through the anterior and posterior approaches, and with postoperative immobilization with plaster braces. The first types of really effective instrumentations were created sequentially by Harrington and Luque, and in parallel with their development, the pedicle screws (Roy-Camille) were introduced into practice. We had to wait another 20 years before the segmental 3D strategy and CD instrumentation appeared, which remain the basis of modern spinal technologies to this day, regardless of the type of anchoring elements (hooks, screws, universal clamps or hybrid structures). For the present and the future, early interventions remain indicated for local pathological foci, which are usually the result of congenital anomalies with or without spinal cord compression. But for extended deformities, especially of thoracic localization, plaster and removable braces remain a good choice, regardless of the etiology and the presence or absence of pelvic tilt. When such methods did not give the desired result, a lot of efforts were made using various technologies to preserve the growth potentials of the spinal column without impairing respiratory function. At the same time, it was obvious that the incidence of complications was high, and the need for a final fusion was often stated. Hence the emergence of bipolar minimally invasive technologies with very promising results and significant number of patients who developed a spontaneous bone block, made the fusion surgery meaningless. As for older children and adolescents, the race to achieve maximum Cobb angle correction is becoming more controversial. It has been convincingly shown that it is much more important for the future, from the point of view of spinal function, to achieve 3D dynamic balance, which is determined by intervertebral discs located cranial and caudal to the area of surgical fusion.

Past, present, and future in pediatric spinal surgery.

According the almost 55 years of experience in Pediatric Spinal surgery it was easy for me to describe the evolution during the past of the surgical techniques as well as the indications for spinal deformities done first without any instrumentation (still useful from time to time nowadays), as from the back as on the front, post-operative immobilization achieved thanks to casting. The real instrumentation appeared successively with Harrington, Luque, and simultaneously the introduction of pedicle screw thanks Raymond Roy Camille. It was necessary to wait another 20 years to get the segmental 3D strategy of the CD instrumentation still the basis of modern spinal surgeries techniques whatever using Hooks Screws, Universal clamps or Hybrid constructs. For present & future, Early surgery is still indicated for localized lesion generally secondary to congenital malformations with or without spinal cord decompression. But for extended lesions especially involving the thoracic area cast and brace is still the good choice whatever the etiology with or without pelvic obliquity. When this treatment fails many attempts with various techniques were used with some success for spinal growth without disturbances about the respiratory function. But it was also demonstrated that the number of complications were still high, with in many cases the necessity to perform a final surgical fusion. It is why the development of the bipolar minimal invasive technique appeared, with very promising results, including the fact that a substantial number of patients get a spontaneous fusion, excluding final surgery. For the older or adolescent patients, the evolution toward a race to obtain the maximum correction of the Cobb angle become more and more disputable as is was demonstrated that the most important for the future regarding the spinal function is the 3D dynamic balance of the discs spaces left free below and above the fused area.

The Convex Manipulation: An Alternative Technique in Surgical Treatment of Adolescent Idiopathic Scoliosis

Introduction Concave derotation is the traditional correction maneuver in adolescent idiopathic scoliosis surgery. However, the positioning of thoracic pedicle screws at concave side of the curve can be quite challenging, because of the small pedicle size and the wide variation in its morphological characteristics, due to the vertebral dystrophy observed in scoliotic patients. Then, to reduce risks of neural damages, and ensure the same strenght of derotation maneuver, a convex manipulation through an all-level pedicle screws convex instrumentation can be performed. We report perioperative and 2-year results in a consecutive series of patients treated by convex manipulation through an all-level pedicle screws convex instrumentation. Material and Methods From January 2013 to January 2015 we surgical treated 36 consecutive patients (28 F, 8 M, mean age 13 years) affected by thoracic adolescent idiopathic scoliosis (Lenke type 1, 27 patients, and Lenke type 2, 9 patients). Mean pre-operative Cobb angle was 56°±6° in Lenke type 1 group and 51°±4° plus 32°±3° in Lenke type 2 group. We performed a posterior access only in all patients using polyaxial pedicle screws at each level on the convex side of the curve. Derotation and manipulation maneuvers were performed on the convex prebent rod. In all cases motor-evoked potentials monitoring was used. Mean follow-up time was 27 months. Results The average percentage of coronal correction was 76 ± 5% (mean post-operative Cobb angle 15°±4°), with no neurological complications. Concerning the post-operative kyphosis, we observed a slight decrease of mean values compared with pre-operative measurements (mean reduction of thoracic kyphosis 5°±2°). At 2-year follow-up no changes in coronal nor in sagittal plane were observed. The mean operative time was 210 ± 30 minutes, with a mean blood loss of 500 ± 100 ml. Using the free-hand technique, the mean time of pedicle screws positioning in the thoracic area on the convex side was 2 ± 1 minutes from T6 to T12, and 4 ± 1 minutes from T3 to T5. Whenever included in the area of arthrodesis, T2 was usually instrumented with the Universal Clamps, to reduce the stiffness of the construct. Instead, T1 has never been included in the arthrodesis area. Conclusion This case-series study shows the effectiveness and the safety of convex manipulation in Lenke type 1 and type 2 scoliosis. The coronal correction obtained with this technique is comparable to that obtained with the traditional concave derotation. Other advantages are the short operative time, the low intra-operative blood loss and, mostly, a lower risk of neurological complications.

Effectiveness and Safety of Convex Derotation in Thoracic Adolescent Idiopathic Scoliosis

Introduction Concave derotation is the traditional correction maneuver in adolescent idiopathic scoliosis surgery. However, the positioning of thoracic pedicle screws at the concave side of the curve can be quite challenging, because of the small pedicle size and the wide variation in its morphological characteristics, due to the vertebral dystrophy observed in scoliotic patients. Then, to reduce risks of neural damages and ensure the same strength of derotation maneuver, a convex derotation through an all-level pedicle screws convex instrumentation can be performed. We report perioperative and 1-year results in a consecutive series of patients treated by convex derotation through an all-level pedicle screws convex instrumentation. Materials and Methods From January 2013 to January 2014, we surgically treated 24 consecutive patients (18 female patients and 6 male patients, mean age 13 years) affected by thoracic adolescent idiopathic scoliosis (Lenke Type 1, 19 patients, and Lenke Type 2, 5 patients). Mean preoperative Cobb angle was 56 ± 6 degrees in Lenke Type 1 group and 51 ± 4 degrees plus 32 ± 3 degrees in Lenke Type 2 group. We performed a posterior access only in patients using polyaxial pedicle screws at each level on the convex side and two sublaminar acrylic loops (universal clamps) at the upper instrumented vertebra, to reduce the stiffness of the construct. Derotation maneuver was performed on the convex prebent rod. In all cases, motor-evoked potential monitoring was used. Mean follow-up time was 15 months. Results The average percentage of coronal correction was 76 ± 5% (mean postoperative Cobb angle 15 ± 4 degrees), with no neurological complications. Regarding the postoperative kyphosis, we observed a slight decrease in mean values compared with preoperative measurements (mean reduction of thoracic kyphosis 5 ± 2 degrees). At 1-year follow-up, no changes in coronal or sagittal plane were observed. The mean operative time was 210 ± 30 minutes, with a mean blood loss of approximately 500 ± 100 mL. Using the free-hand technique, the mean time of pedicle screws positioning in the thoracic area on the convex side was approximately 2 ± 1 minutes from T6 to T12 and approximately 4 ± 1 minutes from T3 to T5. Whenever included in the area of arthrodesis, T2 was usually instrumented with the universal clamps. Instead, T1 has never been included in the arthrodesis area. Conclusion This case-series study shows the effectiveness and safety of convex derotation in Lenke Type 1 and 2 scoliosis. The coronal correction obtained with this technique is comparable to that obtained with the traditional concave derotation. Other advantages are short operative time, low intraoperative blood loss, and, mostly, a reduced risk of neurological complications.

Adolescent idiopathic scoliosis correction achieved by posteromedial translation using polyester bands: A comparative study of subtransverse process versus sublaminar fixation

PurposeSublaminar polyester bands have been used in hybrid construct to achieve correction of adolescent idiopathic scoliosis since 2003. Despite the reported safety of the bands, some surgeons remain reluctant at the idea of approaching the canal because of the potential neurological complications reported with the Luque wiring. Sub transverse bands might be an alternative. The present study is the first to compare sublaminar polyester band fixation to fixation of polyester bands around the transverse processes in hybrid constructs used to treat AIS. MethodsTwo cohorts of consecutive patients treated for thoracic AIS were retrospectively reviewed, with a minimum 2-year follow-up. Posteromedial translation was used for main curve correction in all cases. Sublaminar polyester bands were used in group 1 (20 patients). In group 2 (20 patients), the same implant was used, but the bands were passed around the transverse process instead of the lamina. Radiographic analysis included frontal Cobb angle measurements for each curve, thoracic kyphosis and rotation of the apical vertebra (RVA). ResultsMean operative time was similar in groups 1 and 2 (235±35 and 240±30minutes, respectively). Mean frontal correction achieved for the main curve was similar in both groups, 62.5±17.4% in group 1 and 54.1±19.4% in group 2. Sagittal correction was similar, with a final mean thoracic kyphosis of 30.9°±9.7° and 27.8°± 6.8° in group 1 and 2, respectively. Correction of RVA was similar in both groups postoperatively, 65.8% (±29.1) and 54.4% (±42.7) in group 1 and 2 respectively. No transverse process or lamina fracture was observed during insertion of the bands or curve correction in any of the groups. ConclusionThis study confirms that anchorage of Universal clamps (UCs) around transverse processes is a safe and efficacious technique in both the frontal and sagittal planes, providing a useful alternative for the correction of moderate AIS. UCs attached to transverse processes can achieve correction of moderate AIS similar to that obtained with sublaminar UCs while further reducing risks of vertebral canal complications. Level of evidenceLevel IV.

The Universal Clamp hybrid system: a safe technique to correct deformity and restore kyphosis in adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a tridimensional deformity characterized by coronal and sagittal profiles changes. We present a series of 62 patients affected by AIS and treated by thoracic Universal Clamps and transpedicular lumbar screws hybrid system. Mean age was 13 years. Average pre-operative Cobb angle was 63° ± 12°. Patients were divided into two groups depending on the kyphosis angle: lower than 45° (51 patients, 82.3 %, mean 21° ± 3°) and higher than 45° (11 patients, 17.7 %, mean 62° ± 6°). The average percentage of coronal correction was 70 ± 3 % (mean post-operative Cobb angle 19° ± 4°, P < 0.001). In patients with pre-operative physiological thoracic kyphosis-hypokyphosis, we observed an increase in the average value (32° ± 4°, P < 0.001), while in patients with pre-operative hyperkyphosis, mean decrease of thoracic kyphosis was 19° ± 3° (43° ± 4°, P < 0.001). This case-series study showed the efficacy and safety of Universal Clamp hybrid system in correcting coronal deformity and restoring physiological thoracic kyphosis in patients affected by AIS.

Influence of screw type on initial coronal and sagittal radiological correction with hybrid constructs in adolescent idiopathic scoliosis. Correction priorities

Pedicle screw constructs for spinal instrumentation in patients with adolescent idiopathic scoliosis (AIS) are effective in providing coronal plane correction but can result in loss of kyphosis, which in turn can lead to loss of lordosis. Hybrid constructs have been found superior over pedicle screw constructs in terms of thoracic kyphosis restoration. In this study, our objective was to compare outcomes with monoaxial versus polyaxial screws in an AIS population treated with hybrid constructs. Monoaxial screws provide better correction in the coronal plane but result in loss of thoracic kyphosis, whereas thoracic kyphosis is preserved when polyaxial screws are used. We retrospectively analysed data from 60 patients (mean age, 15years) with Lenke 1, 2, or 3 AIS treated using a hybrid construct with self-retaining bilaminar hook claws cranially, pedicle screws between the last instrumented vertebra and T11 caudally, and sublaminar universal clamps between the two extremities of the construct. Monoaxial screws were used in the first 30 patients (MS group) and polyaxial screws in the next 30 patients (PS group). Student's t test was performed to compare the two groups in terms of thoracic Cobb angle correction and T4-T12 kyphosis 3 months after surgery. No significant preoperative differences were found between the two groups. At last follow-up, the residual Cobb angle was significantly greater in the PS group than in the MS group (20.3° versus 15°) with a percentage of correction of 72.1% in the MS group versus 64.8% in the PS group. In the sagittal plane, the thoracic kyphosis was significantly greater in the PS group than in the MS group (26.6° versus 23°). This preliminary study shows that, even within a population managed using hybrid constructs, which are associated with less iatrogenic hypokyphosis, differences exist according to the technique used. The importance of sagittal spinal balance has been abundantly documented in the literature, and sagittal malalignment, particularly due to iatrogenic factors, is associated with poorer clinical outcomes in adults with spinal deformities. Therefore, there is a critical need to determine whether the treatment priority is optimal correction in the coronal plane or in the sagittal plane. We believe that the main focus should be sagittal plane correction, even at the expense of a slight decrease in coronal plane correction. Long-term studies are needed to confirm our preliminary findings.

Sagittal alignment of the cervical spine in adolescent idiopathic scoliosis treated by posteromedial translation

To analyze postoperative changes in the cervical sagittal alignment (CSA) of patients with AIS treated by posteromedial translation. 49 patients with thoracic AIS underwent posterior arthrodesis with hybrid constructs, combining lumbar pedicle screws and thoracic universal clamps. Posteromedial translation was the main correction technique used. 3D radiological parameters were measured from low-dose biplanar radiographs. CSA was assessed using the C2C6 angle, and the central hip vertical axis (CHVA) was used as a reference axis to evaluate patients' balance. Preoperatively, 58 % of patients had thoracic hypokyphosis, and 79 % had a kyphotic CSA. Significant correlation was found (r = 0.45, P = 0.01) between thoracic hypokyphosis and cervical kyphosis. Increase in T4-T12 thoracic kyphosis (average 14.5° ± 10°) was associated with significant decrease in cervical kyphosis in the early postoperative period. The CSA further improved spontaneously during follow-up by 7.6° (P < 0.0001). Significant positive correlation (r = 0.32, P = 0.03) was found between thoracic and cervical improvements. At latest follow-up, 94 % of the patients were normokyphotic and 67 % had a CSA in the physiological range. Sagittal balance of the thoracolumbar spine was not significantly modified postoperatively. However, the procedure significantly changed the position of C2 in regard to the CHVA (C2-CHVA), which reflects headposition (P = 0.012). At last follow-up, the patients sagittal imbalance was not significantly different from the preoperative imbalance (P = 0.34). Thoracic hypokyphosis and cervical hypolordosis, observed in AIS, can be improved postoperatively, when the posteromedial translation technique is used for correction. The cervical spine remains adaptable in most patients, but the proportion of patients with physiological cervical lordosis at final follow-up remained low (24.5 %).

Sagittal profile control in patients affected by neurological scoliosis using Universal Clamps: a 4-year follow-up study

Patients affected by cerebral palsy often develop progressive scoliosis that can results in trunk instability with an impairment of both coronal and sagittal balance. The aim of this retrospective study was to demonstrate the ability of UC to control the sagittal profile in a consecutive series of patients affected by neurological scoliosis. From 2006 to 2008, 84 patients (57 F, 27 M) affected by neurological scoliosis were treated surgically. Mean age was 14 years (range 10-17). The etiology was mainly cerebral palsy. The average pre-operative Cobb angle was 73° ± 16°. Patients were divided into three groups according to the pre-operative presence of: physiological kyphosis (mean 29° ± 8°), thoracic lordosis (mean 10° ± 6°) and hyperkyphosis (51° ± 8°). A posterior access was performed in all patients using thoracic UC associated with transpedicular lumbar screws and a conventional claw at the upper extremity of the construct. The average percentage of coronal correction was 72%. In all three groups, we observed a common trend toward maintaining or restoring the physiological values. Mean follow-up time was 36 months. At the 1-year follow-up, the mean loss of correction was 7° ± 2° in the coronal plane and 2° ± 1° in the sagittal plane with no other change thereafter. The hybrid construct using UC appears effective in neurological scoliosis treatment, providing a good correction of the deformity in both coronal and sagittal planes. In the present series, physiological thoracic kyphosis has been restored in all patients, providing better sitting tolerance in wheelchair-bound patients, and retaining standing and walking abilities in ambulatory patients.

Selective thoracolumbar instrumentation with pedicle screws and sublaminar bands (universal clamps) in adolescent idiopathic scoliosis

Selective thoracolumbar instrumentation with pedicle screws and sublaminar bands (universal clamps) in adolescent idiopathic scoliosis

Angle Measurement Reproducibility Using EOSThree-Dimensional Reconstructions in Adolescent Idiopathic Scoliosis Treated by Posterior Instrumentation

A reproducibility study was conducted in preoperative and postoperative three-dimensional (3D) measurements for patients operated for adolescent idiopathic scoliosis (AIS). To assess the reliability of preoperative and postoperative 3D reconstructions using EOS in patients operated for AIS. No prior reliability study of 3D measurements has been performed in the literature for severe scoliosis and for operated patients. This series included 24 patients (62° ± 11) operated for Lenke 1 or 2 AIS, using either all-pedicle screw constructs (group 1) or hybrid constructs, with universal clamps at thoracic levels (group 2). All patients underwent low-dose standing biplanar radiographs, pre- and postoperatively. Three operators performed the 3D reconstruction process two times preoperatively and two times postoperatively (total 288 reconstructions). Intraoperator repeatability and interoperator reproducibility were calculated and compared between groups. The preoperative reproducibility was between 4° and 6.5° for parameters dedicated to scoliosis (Cobb and apical vertebral rotation), between 4° and 7° for kyphosis and lordosis values, and between 1° and 5° for pelvic measurements. The postoperative reproducibility was between 5° and 8° for values of kyphosis and lordosis, between 1° and 5.5° for pelvic parameters, and between 6.5° and 10.5° for the scoliotic parameters. The reproducibility of the scoliotic parameters was slightly better in the hybrid construct group, but the difference was not significant (P = 0.8). No difference was found between groups for the other parameters. 3D postoperative reconstructions are as reproducible as preoperative ones. The reproducibility is not influenced by the type of implant used for correction. Mean difference between operator was higher than previously reported for the apical rotation measurement, but this difference can be explained by the severity of the curves and the lower visibility of the anatomical landmarks due to the implants.

Surgical treatment of neurological scoliosis using hybrid construct (lumbar transpedicular screws plus thoracic sublaminar acrylic loops)

In the nineties, most spinal surgeons supported the validity of segmental spine instrumentation, but this procedure has progressively been abandoned because difficult and with a high risk of neurological complications, in favor of the Cotrel-Dobousset (CD). The CD instrumentation is based on segmentation of curves, thus improving the angular correction and actuates sagittal profile. Sublaminar acrylic loops (Universal Clamp) shows the same resistance to stress as steel or titanium alloy sublaminar wires. The simple procedure and the tensioning of the strips allows re-tensioning and progressive correction. The increased contact area, improves corrective forces, thus reducing the risk of laminar fractures. The aim of this study was to verify the validity of this spinal fixation implant in the surgical treatment of a consecutive series of patients affected by neurologic scoliosis. The authors treated surgically 84 patients affected by neurologic scoliosis with an average age of 14 years (range 10-17). Universal Clamps associated with Socore TM spinal assembly, transpedicular lumbar screws and thoracic hooks at the upper end of the curve were used. The etiology of disease was cerebral palsy in 81 cases, Friedreich ataxia in two cases and Aicardi syndrome in one case. The average preoperative angular value was 73° ± 16°. It was implanted a mean of seven Clamps for each procedure (range 5-9). The average percentage of correction was 72%. Mean operative time was 240 ± 30 min with mean blood loss of 1200 ± 400 ml. No intra-operative complications occurred. Mean follow-up was 36 months. At one-year follow-up the mean loss of correction was 7° ± 2° with no re-intervention required. This is the first report on treatment of neurological scoliosis with this hybrid construct (lumbar screws, thoracic acrylic clamps, thoracic hooks at the upper end of the curve). In this group of patients the Universal Clamps technique appeared safe and effective and its mechanical performance is comparable to all-level screws construct. Furthermore, the kyphotic component can be better managed in case of thoracic lordosis. The most important aspect of this technique is a short operative time and low vascular and neurologic risks combined with a satisfying stability in the short-postoperative period. Nevertheless, it is important to value results on a long-term follow-up to analyze correction loss, pseudoarthrosis, and mechanical failure of the strips.

Hybrid Constructs for Tridimensional Correction of the Thoracic Spine in Adolescent Idiopathic Scoliosis

Retrospective study of prospectively collected data. Compare Universal Clamps (UCs) and hooks for the thoracic correction of adolescent idiopathic scoliosis (AIS). In scoliosis surgery, sagittal correction is as important as frontal correction due to the risk of junctional kyphosis. Compared to all-screw constructs, hybrid constructs with lumbar pedicle screws and thoracic hooks or sublaminar wires have been shown to achieve similar coronal correction while providing superior postoperative thoracic kyphosis. The authors used a novel sublaminar thoracic implant, the UC with improvements over sublaminar wires. Hybrid constructs using thoracic UCs were compared to those with thoracic hooks. This series involved 150 patients treated for AIS with hybrid constructs. A total of 75 consecutive patients operated from 2001 to 2003, who had thoracic hooks with in situ contouring, distraction, and compression (Group 1), were compared to 75 consecutive patients operated from 2004 to 2006, who had thoracic UCs with posteromedial translation (Group 2). All had intraoperative somatosensory/motor-evoked potential monitoring and at least 2-years follow-up. Except for follow-up (longer in Group 1), the 2 groups were similar before surgery. The UCs achieved better thoracic coronal correction (P < 0.001), Cincinnati index (P < 0.001), kyphosis (P = 0.02), and apical rotation (P < 0.001). In normokyphotic or hypokyphotic patients, the UC corrected thoracic kyphosis by 11.2 degrees (55%) versus 0.4 degrees (2%) achieved by hooks (P < 0.0001). These differences were stable at last follow-up. There were no intraoperative complications or changes in somatosensory/motor-evoked potentials. UC reduced operative time by 20% (60 minutes; P < 0.001) and blood loss by 23% (250 mL; P < 0.001). Although both of these hybrid constructs efficaciously corrected the coronal and axial deformities in AIS, the results of the UC technique were superior to those achieved with hooks in all 3 planes, especially the sagittal plane. Moreover, the UC technique is straightforward and safe, reducing both operative duration and blood loss.

Universal Clamp system in thoracolumbar spinal fixation: technical note

The Universal Clamp is a polyester band passed under the lamina and connected to a rod by a titanium clamp that has been recently reported as an alternative for replacing screws and hooks for thoracolumbar spinal diseases. To date, there is no report of an evaluation of the effectiveness and safety of posterior fixation and fusion using this technique. This study was a prospective evaluation of a cohort of 18 patients with thoracolumbar disorders that were surgically treated between November 2006 and June 2007 with Universal Clamps for spinal fixation. Fifteen cases were traumatic fractures with others two with degenerative severe stenosis and one kyphotic stenosis. Levels treated were thoracolumbar in 15 cases, thoracic in two cases, and lumbar in one case. Seventeen patients underwent correction and instrumentation using a hybrid construct of screws and clamps, while one patient underwent fixation using Universal Clamps only. Intraoperative evoked potentials were monitored in all cases. One patient had infection that resolved after antibiotic therapy without implant removal. No neurological adverse event was seen. There was no rod breakage or clamp loosening during a follow-up of 12 months. The polyester band is soft and flexible, and the anterior-posterior spinal canal space occupied by the band is less than by sublaminar wire steel cable, thus avoiding direct spinal cord trauma during sublaminar passage. The flat configuration of the cable distributes the load over a larger contact area under the lamina compared to metal wires without producing imaging artefacts in postoperative imaging. This preliminary report demonstrates the efficacy and safety of this technique for the stabilization of thoracolumbar spinal disorders.

Efficacy and safety of posteromedial translation for correction of thoracic curves in adolescent idiopathic scoliosis using a new connection to the spine: the Universal Clamp

Correction of adolescent idiopathic scoliosis (AIS) has been reported with various systems. All-screw constructs are currently the most popular, but they have been associated with a significant decrease in thoracic kyphosis, with a potential risk of junctional kyphosis, not observed with hybrid constructs in the literature. In addition, it is important to weigh potential advantages of pedicle screw fixation against risks specific to its use. Because hybrid constructs are associated with a lower risk of complications and better sagittal correction than all-screw constructs, at present we use lumbar pedicle screws combined with a new sublaminar connection to the spine (Universal Clamps) at thoracic levels. The purpose of this study was to determine the efficacy and safety of the Universal Clamp (UC) posteromedial translation technique for correction of AIS. Seventy-five consecutive patients underwent posterior spinal fusion and hybrid instrumentation for progressive AIS. Correction was performed at the thoracic level using posteromedial translation. At the lumbar level, correction was performed using in situ contouring and compression/distractions maneuvers. A minimum 2-year follow-up was required. Medical data and radiographs were prospectively analyzed and compared using a paired t test. The average age at surgery was 15 years and 4 months (+/-19 months). The average number of levels fused was 12+/-1.6. The mean follow-up was 30+/-5 months. The average preoperative Cobb angle of the major curve was 60 degrees+/-20 degrees. The immediate postoperative major curve correction averaged 66+/-13%. The average loss of correction of the major curve between the early postoperative assessment and latest follow-up was 3.5 degrees+/-1.4 degrees . The mean Cincinnati correction index was 1.7+/-0.8 postoperatively, and 1.57+/-1 at last follow up. The mean rotation of the apical vertebra was corrected from 23.3 degrees+/-9 degrees preoperatively to 7.3 degrees+/-5 degrees at last follow up (69% improvement, P<0.0001). In the sagittal plane, the mean thoracic kyphosis improved from 23.8 degrees+/-14.2 degrees preoperatively to 32.3 degrees+/-7.3 degrees at last follow up. For the 68 patients who had a normokyphotic or a hypokyphotic sagittal modifier, thoracic kyphosis increased from 20.5 degrees+/-9.9 degrees to 31.8 degrees+/-7.4 degrees, corresponding to a mean kyphosis correction of 55% at last follow up. No intraoperative complication occurred and none of the patients developed proximal junctional kyphosis during the follow up. The principal limitation of the UC technique was the rate of proximal posterior prominence (14.6%), leading us to recommend the use of conventional claws at the upper extremity of the construct. The technique was safe, and reduced operative time, radiation exposure, and blood loss. While achieving correction of deformity in the coronal and axial planes equivalent to the best reported results of all-screw or previous hybrid constructs, the UC hybrid technique appears to provide superior correction in the sagittal plane. The excellent outcome in all three planes was maintained at 2 year follow up.

Development of the small AO fixator to the current set

An indirect system to reduce and hold comminuted fractures of the distal radius was developed in the mid 1970's starting with a simple threaded distraction rod and advancing to a versatile system of rods and universal clamps. This system has gained wide acceptance since then and is used for the wrist joint and for other indications in surgery of the hand, the upper limb, the foot and in paediatric orthopaedics.