[Surgical treatment of kyphosis in children and adolescents]. / Operative Therapie von Kyphosen im Kindesalter.

OBJECTIVE: Correction of a pathological kyphosis to restore a balanced, low-pain or pain-free and load-bearing spine. INDICATIONS: Pronounced sagittal imbalance, progressive kyphosis despite conservative therapy, and neurological deficits are indications for surgery. Further surgical indications are severe therapy-resistant complaints and/or psychologically burdening cosmetic impairment. The guidelines for surgical indications are kyphosis angles of 75-80° thoracic and 30-50° lumbar. CONTRAINDICATIONS: No specific, but general contraindications for surgical treatment. SURGICAL TECHNIQUE: Depending on the characteristics of the kyphosis, different surgical techniques are used. Rod-screw systems are mainly used, and surgery is primarily performed by shortening the spinal column from posterior using a wide variety of techniques. In individual cases, this can be combined with ventrally mobilizing, resecting, or straightening techniques. POSTOPERATIVE MANAGEMENT: The aim of surgical treatment is to achieve a primarily stable and weight-bearing spine. Regular wound control as well as stabilizing physiotherapy during follow-up are essential. Postoperatively, initially abstaining from sports; later physical activity is encouraged under professional guidance. RESULTS: The literature shows very good corrective results in children and adolescents. The technical procedures are associated with a low and acceptable complication rate. Over the course of time, these patients must be monitored in order to detect possible long-term complications such as junctional kyphosis or pseudarthrosis.

Management of complications of mega-implants following treatment of primary and periprosthetic fractures of the lower extremities.

In recent years, indications for implanting mega-implants were established in managing major bone defects linked to revision arthroplasty due to loosening, periprosthetic fractures, re-implantation following periprosthetic joint infection, non-union following fractures as well as complex intraarticular primary fractures. This study was conducted to discuss and analyze the strategy of diagnosis and management of complications following the use of mega-implants in treating primary and periprosthetic fractures of the lower extremities. This is a monocentric retrospective study. Patients aged ≥ 18 years who underwent implantation of a megaendoprosthesis due to periprosthetic or primary fractures of the lower extremity between January 2010 and February 2023 were identified from the authors' hospital information system. We identified 96 patients with equal numbers of fractures (71 periprosthetic fractures and 25 primary fractures). 90 cases out of 96 were investigated in this study. The drop-out rate was 6.25% (six cases). The average follow-up period was 22 months (1 to 8 years) with a minimum follow-up of 1 year. The diagnosis of complications was provided on the basis of subjective symptoms, clinical signs, radiological findings and laboratory investigations such as C-reactive protein, leucocyte count and the microbiological findings. The indications for implantations of modular mega-implants of the lower extremities were periprosthetic fractures (65 cases/72.22%) and primary fractures (25 cases/27.78%). Pathological fractures due to malignancy were encountered in 23 cases (25.56%), in one case due to primary tumor (1.11%) and 22 cases due to metastatic lesions (24.44%). Two cases (2.22%) presented with primary intraarticular fractures with severe osteoporosis and primary arthrosis. In all cases with malignancy staging was performed. Regarding localization, proximal femur replacement was encountered in 60 cases (66.67%), followed by distal femur replacement (28 cases/31.11%) and total femur replacement (2 cases/2.22%). The overall complication rate was 23.33% (21 complications in 21 patients). The most common complication was dislocation which was encountered in nine cases (10%), all following proximal femoral replacement (9 cases out of 60, making 15% of cases with proximal femoral replacement). The second most common complication was infection (six cases, 6.67%), followed by four aseptic loosenings (4.44%), further intraoperative periprosthetic fracture in one case (1.11%) and a broken implant in one case (1.11%). We noticed no cases with wear and tear of the polyethylene components and no cases of disconnections of the modular components. Mega-endoprostheses enable versatile management options in the treatment of primary and periprosthetic fractures of the lower extremities. The rate of complications such as loosening, implant failure, dislocation and infection are within an acceptable range in this preliminary analysis. However, implantation of mega-endoprostheses must be strictly indicated due the limited salvage options following surgery.

Does the intraoperative 3D-flat panel control of the planned implant position lead to an optimization and increased in safety in the anatomically demanding region C1/2?

BACKGROUND: The aim of this study was to evaluate the applicability and advantages of intraoperative imaging using a 3D flat panel in the treatment of C1/2 instabilities. MATERIALS: Prospective single-centered study including surgeries at the upper cervical spine between 06/2016 and 12/2018. Intraoperatively thin K-wires were placed under 2D fluoroscopic control. Then an intraoperative 3D-scan was carried out. The image quality was assessed based on a numeric analogue scale (NAS) from 0 to 10 (0 = worst quality, 10 = perfect quality) and the time for the 3D-scan was measured. Additionally, the wire positions were evaluated regarding malpositions. RESULTS: A total of 58 patients were included (33f, 25 m, average age 75.2 years, r.:18-95) with pathologies of C2: 45 type II fractures according to Anderson/D'Alonzo with or without arthrosis of C1/2, 2 Unhappy triad of C1/2 (Odontoid fracture Type II, anterior or posterior C1 arch-fracture, Arthrosis C1/2) 4 pathological fractures, 3 pseudarthroses, 3 instabilities of C1/2 because of rheumatoid arthritis, 1 C2 arch fracture). 36 patients were treated from anterior [29 AOTAF (combined anterior odontoid and transarticular C1/2 screw fixation), 6 lag screws, 1 cement augmented lag screw] and 22 patients from posterior (regarding to Goel/Harms). The median image quality was 8.2 (r.: 6-10). In 41 patients (70.7%) the image quality was 8 or higher and in none of the patients below 6. All of those 17 patients the image quality below 8 (NAS 7 = 16; 27.6%, NAS 6 = 1, 1.7%), had dental implants. A total of 148 wires were analyzed. 133 (89.9%) showed a correct positioning. In the other 15 (10.1%) cases a repositioning had to be done (n = 8; 5.4%) or it had to be drawn back (n = 7; 4.7%). A repositioning was possible in all cases. The implementation of an intraoperative 3D-Scan took an average of 267 s (r.: 232-310 s). No technical problems occurred. CONCLUSION: Intraoperative 3D imaging in the upper cervical spine is fast and easy to perform with sufficient image quality in all patients. Potential malposition of the primary screw canal can be detected by initial wire positioning before the Scan. The intraoperative correction was possible in all patients. Trial registration German Trials Register (Registered 10 August 2021, DRKS00026644-Trial registration: German Trials Register (Registered 10 August 2021, DRKS00026644- https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00026644 ).

The effects of force application on the compressive properties of femoral spongious bone.

BACKGROUND: End artefacts play a major role in uniaxial compression tests with cancellous bone specimens. They lead to misinterpretation of mechanical parameters of bones due to uncontrolled introduction of bending moments into the free ends of trabeculae. This work aims to simplify current methods preventing end-artefacts and furthermore to investigate the influence of end artefacts on plateau stress. METHODS: 176 cylindrical cancellous bone specimens were taken from human femoral condyles and tested in uniaxial compression. The specimens were divided into 2 groups (direct, end-cap) and compressive modulus, maximum stress, plateau stress, energy absorbtion as well as apparent density were evaluated. Density values are from separate specimens which are immediately adjacent to the mechanical specimen. FINDINGS: All mechanical parameters were significantly higher in the end-cap specimens than in the direct ones by about 30 - 40 %, thus reaching similar differences as the previous studies. Greatest differences between groups were determined for compressive modulus (45 %) and plateau stress (35 %). Energy absorbtion can be explained with great accuracy by plateau stress (P < 0.001; R2 = 0.95). Among all parameters plateau stress can be best explained by apparent density using an exponential function (P < 0.001; R2 = 0.38). INTERPRETATION: The end-cap method used here to prevent end artefacts showed variations consistent with the literature when compared to the direct method. Additionally it was shown that the way in which the force is applied to the specimen has a major influence on the failure progression behavior, which was characterized using the plateau stress.

Effect of subsequent vertebral body fractures on the outcome after posterior stabilization of unstable geriatric fractures of the thoracolumbar spine.

PURPOSE: The purpose of this study was analyzing the effect of subsequent vertebral body fractures on the clinical outcome in geriatric patients with thoracolumbar fractures treated operatively. METHODS: Retrospectively, all patients aged ≥ 60 with a fracture of the thoracolumbar spine included. Further inclusion parameters were acute and unstable fractures that were treated by posterior stabilization with a low to moderate loss of reduction of less than 10°. The minimal follow-up period was 18 months. Demographic data including the trauma mechanism, ASA score, and the treatment strategy were recorded. The following outcome parameters were analyzed: the ODI score, pain level, satisfaction level, SF 36 score as well as the radiologic outcome parameters. RESULTS: Altogether, 73 patients were included (mean age: 72 years; 45 women). The majority of fractures consisted of incomplete or complete burst fractures (OF 3 + 4). The mean follow-up period was 46.6 months. Fourteen patients suffered from subsequent vertebral body fractures (19.2%). No trauma was recordable in 5 out of 6 patients; 42.8% of patients experienced a low-energy trauma (significant association: p < 0.01). There was a significant correlation between subsequent vertebral body fracture and female gender (p = 0.01) as well as the amount of loss of reduction (p = 0.02). Thereby, patients with subsequent vertebral fractures had significant worse clinical outcomes (ODI: 49.8 vs 16.6, p < 0.01; VAS pain: 5.0 vs 2.6, p < 0.01). CONCLUSION: Patient with subsequent vertebral body fractures had significantly inferior clinical midterm outcome. The trauma mechanism correlated significantly with both the rate of subsequent vertebral body fractures and the outcome. Another risk factor is female gender.

Patient-Matched 3-D-Printed Guides for the Insertion of Cervical Pedicle Screws in Tumor Surgery.

BACKGROUND: Pedicle screw fixation in the cervical spine provides biomechanical advantages compared to other stabilization techniques. However, pedicle screw insertion in this area is challenging due to the anatomical conditions with a high risk of breaching the small pedicles and violating the vertebral artery or neural structures. Today, several techniques to facilitate screw insertion and to make the procedure safer are used. 3-D-printed patient-matched guides based on a CT reconstruction are a helpful technique which allows to reduce operation time and to improve the safety of pedicle screw insertion at the cervical spine. CASES: 3-D-printed patient-matched drill guides based on a CT scan with a 3-D reconstruction of the spine were used in two challenging cervical spine surgical tumor cases to facilitate the implantation of the pedicle screws. The screw position was controlled postoperatively by means of the routinely performed CT scan. RESULTS: Postoperative imaging (conventional radiographs and CT scan) revealed the correct position of the pedicle screws. The time needed for screw insertion was short, and the need for intraoperative fluoroscopy could be reduced. There was no intra- or postoperative complication related to the pedicle screw implantation. Both tumors could be removed completely. CONCLUSION: These preliminary results show that 3-D-printed patient-specific guides are a promising tool to support and facilitate the implantation of cervical pedicle screws. The time needed for insertion is short, and intraoperative fluoroscopy time can be reduced. This technique allows for both a meticulous preoperative planning and a correct and therefore safe intraoperative positioning of cervical spine pedicle screws.

Influence of osteoporosis on the compressive properties of femoral cancellous bone and its dependence on various density parameters.

Data collection of mechanical parameters from compressive tests play a fundamental role in FE modelling of bone tissues or the developing and designing of bone implants, especially referring to osteoporosis or other forms of bone loss. A total of 43 cylindrical samples (Ø8 × 16 mm) were taken from 43 freshly frozen proximal femora using a tenon cutter. All femora underwent BMD measurement and additionally apparent- and relative- and bulk density (ρapp, ρr, ρb) were determined using samples bordering the compressive specimen on the proximal and distal regions. All samples were classified as "normal", "osteopenia" and "osteoporosis" based on the DEXA measurements. Distal apparent density was most suitable for predicting bone strength and BMD. One novel aspect is the examination of the plateau stress as it describes the stress at which the failure of spongious bone progresses. No significant differences in mechanical properties (compressive modulus E; compressive stress σmax and plateau stress σp) were found between osteopenic and osteoporotic bone. The results suggest that already in the case of a known osteopenia, actions should be taken as they are applied in the case of osteoporosis A review of the literature regarding extraction and testing methods illustrates the urgent need for standardized biomechanical compressive material testing.

Cervical spine injury after virtual reality gaming: a case report.

BACKGROUND: We report a patient who fractured the seventh cervical vertebra while playing a virtual reality (VR) game, without any other trauma. This case report aims to describe the spinal trauma incurred during the use of a VR headset in a video game. CASE PRESENTATION: The Caucasian patient presented with pain and swelling in the lower cervical spine at our clinic after playing a video game involving a combination of shoulder, arm and head movements while wearing a VR headset. Preexisting comorbidities were not present in the 31-year-old male. No history of regular medication use or drug abuse was recorded. After performing a clinical examination and radiological diagnostics, we found a dislocated traumatic fracture of the spinous process of the seventh cervical vertebra. After a soft tissue defect was excluded through magnetic resonance imaging (MRI) diagnostics, a conservative therapy regimen with pain therapy and immobilization was started. After hospitalization, outpatient controls were conducted at 4, 6 and 12 weeks. At 6 weeks after hospitalization, the patient had recovered from the injury without complications. CONCLUSIONS: Rapid movements during VR gaming can lead to injuries of the cervical spine. In addition to rapid movements, the additional weight of the VR headset as well as the decoupling of audiovisual stimuli from the perceived proprioceptive information should be considered. Determining whether this is an isolated incident induced by unknown preexisting factors or whether the trauma mechanism alone can lead to severe spinal trauma needs to be studied further with additional cases.

Comparison of three different screw trajectories in osteoporotic vertebrae: a biomechanical investigation.

BACKGROUND: Pedicle screw insertion in osteoporotic patients is challenging. Achieving more screw-cortical bone purchase and invasiveness minimization, the cortical bone trajectory and the midline cortical techniques represent alternatives to traditional pedicle screws. This study compares the fatigue behavior and fixation strength of the cement-augmented traditional trajectory (TT), the cortical bone trajectory (CBT), and the midline cortical (MC). METHODS: Ten human cadaveric spine specimens (L1 - L5) were examined. The average age was 86.3 ± 7.2 years. CT scans were provided for preoperative planning. CBT and MC were implanted by using the patient-specific 3D-printed placement guide (MySpine®, Medacta International), TT were implanted freehand. All ten cadaveric specimens were randomized to group A (CBT vs. MC) or group B (MC vs. TT). Each screw was loaded for 10,000 cycles. The failure criterion was doubling of the initial screw displacement resulting from the compressive force (60 N) at the first cycle, the stop criterion was a doubling of the initial screw displacement. After dynamic testing, screws were pulled out axially at 5 mm/min to determine their remaining fixation strength. RESULTS: The mean pull-out forces did not differ significantly. Concerning the fatigue performance, only one out of ten MC of group A failed prematurely due to loosening after 1500 cycles (L3). Five CBT already loosened during the first 500 cycles. The mean displacement was always lower in the MC. In group B, all TT showed no signs of failure or loosening. Three MC failed already after 26 cycles, 1510 cycles or 2144 cycles. The TT showed always a lower mean displacement. In the subsequent pull-out tests, the remaining mean fixation strength of the MC (449.6 ± 298.9 N) was slightly higher compared to the mean pull-out force of the CBT (401.2 ± 261.4 N). However, MC (714.5 ± 488.0 N) were inferior to TT (990.2 ± 451.9 N). CONCLUSION: The current study demonstrated that cement-augmented TT have the best fatigue and pull-out characteristics in osteoporotic lumbar vertebrae, followed by the MC and CBT. MC represent a promising alternative in osteoporotic bone if cement augmentation should be avoided. Using the patient-specific placement guide contributes to the improvement of screws' biomechanical properties.

[Cost coverage for complex paediatric spinal deformities with preoperative halo traction-an economic problem?] / Kostendeckung bei komplexen pädiatrischen Wirbelsäulendeformitäten mit präoperativer Halotraktion ­ ein wirtschaftliches Problem?

BACKGROUND: Spinal surgery is largely reimbursed in a differentiated manner via the DRG system. For treatments of complex paediatric deformities with increased pre and postoperative effort due to special treatment approaches, it seems that the costs for the treatment are not fully covered. MATERIALS AND METHODS: All paediatric cases with surgical treatment of the spine that were treated in a single spine centre from 2018-2020 were considered. The subgroup of patients with inpatient halo-gravity traction (halo group) before surgery was compared with all other cases treated in terms of economic and demographic factors. RESULTS: There were 86 cases that were treated surgically without halo traction and 6 cases with halo traction. The groups did not differ significantly in age (p = 0.41) or Patient Clinical Complexity Level (PCCL, p = 0.76). The average length of hospital stay in the halo group was significantly longer than in the other cases (84.2 ± 40.1 d vs. 11.0 ± 6.4 d; p = 0.001). Due to DRG grouping and long-stay surcharges, the mean revenue per case was significantly higher in the halo group than in the other cases (€ 63,615 ± 45,138 vs. € 16,836 ± 9356) (p = 0.003). The contribution margin for the period of the long-term surcharges varied between 11,394 and 9766 €. The high additional costs due to the necessary medical devices of halo traction were not sufficiently reflected in the reimbursement. CONCLUSION: Paediatric spine surgery can be challenging in special cases. In particular, severe deformities of the spine may require additional procedures. The subgroup of patients requiring preoperative halo traction is not adequately compensated by the DRG system.

Midterm outcome after posterior stabilization of unstable Midthoracic spine fractures in the elderly.

BACKGROUND: The evidence for the treatment of midthoracic fractures in elderly patients is weak. The aim of this study was to evaluate midterm results after posterior stabilization of unstable midthoracic fractures in the elderly. METHODS: Retrospectively, all patients aged ≥65 suffering from an acute unstable midthoracic fracture treated with posterior stabilization were included. Trauma mechanism, ASA score, concomitant injuries, ODI score and radiographic loss of reduction were evaluated. Posterior stabilization strategy was divided into short-segmental stabilization and long-segmental stabilization. RESULTS: Fifty-nine patients (76.9 ± 6.3 years; 51% female) were included. The fracture was caused by a low-energy trauma mechanism in 22 patients (35.6%). Twenty-one patients died during the follow-up period (35.6%). Remaining patients (n = 38) were followed up after a mean of 60 months. Patients who died were significantly older (p = 0.01) and had significantly higher ASA scores (p = 0.02). Adjacent thoracic cage fractures had no effect on mortality or outcome scores. A total of 12 sequential vertebral fractures occurred (35.3%). The mean ODI at the latest follow up was 31.3 ± 24.7, the mean regional sagittal loss of reduction was 5.1° (± 4.0). Patients treated with long segmental stabilization had a significantly lower rate of sequential vertebral fractures during follow-up (p = 0.03). CONCLUSION: Unstable fractures of the midthoracic spine are associated with high rates of thoracic cage injuries. The mortality rate was rather high. The majority of the survivors had minimal to moderate disabilities. Thereby, patients treated with long segmental stabilization had a significantly lower rate of sequential vertebral body fractures during follow-up.

Incomplete burst fractures of the thoracolumbar spine: a review of literature.

PURPOSE: The purpose of this review was to analyze the biomechanical basis of incomplete burst fractures of the thoracolumbar spine, summarize the available treatment options with evidence from the literature, and to propose a method to differentiate fracture severity. METHODS: The injury pattern, classification, and treatment strategies of incomplete burst fractures of the thoracolumbal spine have been described following a review of the literature. All level I-III studies, studies with long-term results and comparative studies were included and summarized. RESULTS: Details of five randomized control trials were included. Additionally, three comparative studies and two studies with long-term outcomes were detailed in this review. The fracture severity reported in the included studies varied tremendously. Most classification used did not adequately describe the complexity of fracture configuration. A wide variety of treatment strategies were outlined, ranging from non-operative therapy to aggressive surgical intervention with combined anterior-posterior approaches. Thus, the treatment of incomplete burst fractures of the thoracolumbar spine is quite diverse and remains controversial. CONCLUSIONS: Incomplete burst fractures can differ tremendously regarding the degree of instability they confer to the thoracolumbar spine. Based on a detailed review of the literature, it is clear that good results can be obtained with both non-operative and operative strategies to treat these injuries. In the authors' opinion, the intervertebral disc plays a key role in determining the long-term clinical and radiological outcome. Thus, an incorporation of the intervertebral disc pathology into the existing classification systems would be a valuable prognostic factor.

Thermomechanical method for cement extraction in revision arthroplasty.

BACKGROUND: In joint revision surgery, bone cement extraction remains a major challenge which even today has not seen a satisfactory solution yet. We studied in an experimental setting the impact of heat sources on the mechanical properties and microstructure of bone cement and determined the glass transition temperature (T G) of bone cement. As a result, it would be possible to establish a thermomechanical method which makes use of the structural and material-specific property changes inherent in bone cement at elevated temperatures. METHODS: Prepared samples of polymerized bone cement were thermoanalyzed with a Netzsch STA 409 C thermal analyzer. Samples weighing approx. 55 mg were heated to 390 °C at a rate of 5 K/min. Both simultaneous differential thermal analysis and thermogravimetry were employed. The thermomechanically induced changes in the microstructure of the material were analyzed with a computed tomography scanner specifically developed for materials testing (3D-µXCT). RESULTS: The bone cement changed from a firm elastic state over entropy-plastic (air atmosphere 60-155 °C) to a plastic viscosity state (air atmosphere >155 °C). Between 290 and 390 °C, the molten mass disintegrated (decomposition temperature). CONCLUSION: Our study was able to determine the glass transition temperature (T G) of bone cement which was about 60 and 65 °C under air and nitrogen, respectively. Heating the dry bone cement up to at least 65 °C would be more than halve the strength needed to detach it. Bone cement extraction would then be easy and swift.

Osteoporotic vertebral body fractures of the thoracolumbar spine: indications and techniques of a 360°-stabilization.

Unstable vertebral body fragility fractures of the thoracolumbar spine can occur with or without relevant trauma. Initially, a standardized diagnostic algorithm including magnetic resonance tomography is recommended to detect accompanied further vertebral body fractures, to interpret the individual fracture stability, and to screen for relevant traumatic intervertebral disc lesions. Aim of the therapy is to assure fast mobilization and to maintain spinal alignment. Unstable fracture morphology is defined by vertebral body fractures including a relevant defect of the posterior vertebral cortex as well as type B or C fractures. With respect of type A fractures, a combined anterior-posterior approach including a primary cement-augmented posterior stabilization and anterior spondylodesis is indicated in those patients with relevant intervertebral lesions or in those suffering from high-energy accidents resulting in unstable burst-type fractures. The others will benefit from hybrid stabilizations including cement-augmented posterior stabilizations and cement augmentation (kyphoplasty) of the fractured level to gain a ventral transosseous stability. In addition, individually adapted antiosteoporotic therapy is essential.

[Conservative treatment of congenital patellar dislocation]. / Konservative Therapie bei kongenitaler Patellaluxation.

This article presents the rare case of a boy who was born in our hospital with valgus deformity and external rotation of the right lower leg because of congenital patellar dislocation. In the case presented a stable repositioning of the patella could be achieved by redressment with a plaster cast and leg brace. During a 4-year follow-up there were no tendencies towards dislocation during the clinical examination and no dislocation events were documented. In selected cases an attempt at conservative repositioning and retention treatment appears to be worthwhile before surgical treatment is indicated.

[Complex Pathologies of the Spine: Trauma meets Degeneration]. / Komplexpathologien an der Wirbelsäule: Trauma trifft Degeneration ­ eine Bestandsaufnahme.

Treating vertebral body fractures is challenging when there is relevant pre-existing spinal degeneration. Both vertebral body fractures and spinal degeneration are related to the physiological aging process. The increases in both are linked to increases in life expectancy. Several factors promote spinal degeneration and increase fracture risk, such as disc degeneration, spinal imbalance and osteoporosis. The main diagnostic and therapeutic challenge is to identify the sources of pain and to start appropriate therapy. A structured and advanced algorithm is then essential. Unstable fractures must always be stabilised. However, surgical strategy may be greatly influenced if there are also degenerative diseases, such as segmental decompression, multisegmental instrumentation or fusion, or complex reconstructive spondylodesis, including osteotomies. Notwithstanding this, the individual therapy concept has to be adapted to the demands and pathology of the individual patient.

[Injuries of the thoracolumbar spine in children]. / Verletzungen der kindlichen thorakolumbalen Wirbelsäule.

BACKGROUND: Injuries of the thoracolumbar spine in children are rare and challenging for the treating physician. Besides knowledge of fracture treatment, the anatomical particularities of the spine in children are of great importance. METHODS: The article gives an overview of the diagnosis and therapy with the most common classification of injuries of the thoracolumbar spine. RESULTS: Taking into account the children's age and the fracture morphology most cases can be treated conservatively, especially because the young spine has great potential for remodelling. The older the child becomes, the more smoothly the transition to adult treatment occurs; thus, unstable fractures should be treated with surgery. CONCLUSION: The difficult indication and the specific characteristics of surgery necessitate treatment in a spine centre with experience with surgery on children.

[Treatment of chronic slipped capital femoral epiphysis : Use of dynamic epiphyseal telescopic screws]. / Behandlung der chronischen Epiphyseolysis capitis femoris : Einsatz der dynamischen epiphysären Teleskopschraube.

BACKGROUND: Slipped capital femoral epiphysis (SCFE) is a multifactorial structural loosening in the area through the epiphyseal plate between the epiphysis and metaphysis accompanied by slippage of the femoral head in the mid-dorsal-caudal direction without additional adequate trauma. In this retrospective study, all patients with chronic SCFE were assessed who had been treated by implanting a dynamic epiphyseal telescopic (DET) screw. METHODOLOGY: All patients who had been treated at our hospital with a DET screw implant between December 2006 and November 2014 following diagnosis of chronic SCFE were included in the study. Clinical and radiological follow-up was carried out after 6 weeks, 12 weeks, and then every 6 months. RESULTS: In all patients, the SCFE proved to have been firmly fixed and no further slippage was observed in any patient on the side affected. None of the prophylactically treated hips showed secondary SCFE either. In all patients, the DET screw led to partial remodeling of the slippage. The average slippage angle according to Southwick (epsilon angle) was about 30° preoperatively and about 19° in the most recent radiological follow-up. The alpha angle according to Nötzli was about 91° preoperatively and about 62° in the most recent radiological follow-up. Most of the patients showed none treatment-related dysfunction. CONCLUSION: Surgical treatment with a DET screw seems to be a safe procedure for both the affected hip and the hip to be treated prophylactically. This method is an adequate alternative to the widespread technique of pinning with K­wires.

[The Effect of Intraoperative Screw Monitoring (Root Monitoring) with the INS-1 System (NUVASIVE) on the Radiological Outcome of Dorsal Instrumentation of the Lumbar Spine]. / Der Einfluss des intraoperativen Nervenwurzelmonitorings mit dem INS-1-System (NuVasive) auf das radiologische Outcome bei dorsaler transpedikulärer Instrumentation der Lendenwirbelsäule.

INTRODUCTION: Transpedicular screw fixation of spinal segments has been described for a variety of surgical indications and is a key element in spinal surgery. The aim of transpedicular screw fixation is to achieve maximal stability. Screw malposition should be obviated to avoid neurological complications. There are published methods of applying evoked EMG to control screw position in relation to neural structures. These studies demonstrated that an intact bony pedicle wall acts as an electrical isolator between the screw and spinal nerve root. The aim of our study was to evaluate the impact of intraoperative pedicle screw monitoring on screw positioning. MATERIAL AND METHODS: We enrolled 22 patients in this prospective randomised study, who underwent spinal instrumentation after being split into two equal groups. In the first group, dorsal instrumentation was supplemented with intraoperative nerve root monitoring using the INS-1-System (NuVasive, San Diego USA). In the second group, screws were inserted without additional pedicle monitoring. All patients underwent monosegmental instrumentation with "free hand implanted" pedicle screws. 44 screws were inserted in each group. The screw position was evaluated postoperatively using CT scans. The position of the screws in relation to the pedicle was measured in three different planes: sagittal, axial and coronal. The accuracy of the screw position was described using the Berlemann classification system. Screw position is classified in three groups: type 1 correct screw position, type 2 encroachment on the inner cortical wall, type 3 pedicle cortical perforation. Screw angulation and secondary operative criteria were also evaluated. RESULTS: The use of neuromonitoring did not influence the distance between the centre of the screws and the pedicle wall. Distances only depended on the implantation side (right and left) and the height of implantation (caudal or cranial screw). Because of the low number of cases, no conclusion could be reached about the influence of root monitoring on the correct positioning of the screws. There was at least a non-significant trend towards more frequent perforation of the pedicle in the monitor group. In the present study, we showed that root monitoring had a significant effect on the scattering of transversal angles. These were increased compared to the control group. Otherwise, the implantation angle was not shown to depend on the use of neuromonitoring. Neuromonitoring did not influence blood loss or operative time. DISCUSSION: The data did not permit any conclusion as to whether this technique can minimise the frequency of pedicle screw malposition. The four coronal plane distances did not depend on the use of neuromonitoring. The inclination angle was also unaffected by neuromonitoring. The only parameter for which we found any effect was the transverse angle. The mean values were similar in both groups, but the variances were not equal. The effect of monitoring on the only parameter which could not be evaluated by fluoroscopy is thus rather unfavourable.