Anna Kathrin Hell

Prof. Dr. Anna Kathrin Hell

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Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 June 2013 in Spine
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Journal Article
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BGBastian Groenefeld
Bastian Groenefeld
AHAnna Kathrin Hell
Anna Kathrin Hell
Study Design. Retrospective analysis of 1328 spinal radiographs of 57 patients after vertical expandable prosthetic titanium rib (VEPTR) implantation with an average follow-up of 30 months. Objective. To evaluate the incidence, time of onset, as well as the underlying factors influencing the occurrence of ossifications in children treated with VEPTR. Summary of Background Data. Spontaneous spinal fusions and ossifications are well known in children treated with spinal implants. In theory, children with spinal deformity and VEPTR implantation are less likely to develop these complications because of either little or no implant contact to the spine. Methods. Fifty-seven patients had a primary VEPTR implantation due to spinal deformity and thoracic insufficiency syndrome and repeated lengthening procedures. The mean age at the time of primary surgery was 7.7 years, the mean duration of follow-up was 29.8 months, and the mean number of operations was 5.9. A total of 1328 spinal radiographs were analyzed with respect to the occurrence and growth of ossifications, implant migration, and other complications. Results. Overall, 24% of the patients (n = 13) had ossifications, which affected in 92% the main load sharing VEPTR implant. The fusions involved in 54% of cases the lumbar spine and in each 23% the ribs and the iliac crest. Ossifications developed in 11% of children within the first year of treatment and increased by about the same rate per annum. After 53 months, 48% of the radiographs showed some ossifications. There was a significant correlation to the stiffness of the deformity and the number of surgical procedures. Conclusion. Contrary to previous assumptions, it was shown that in children treated with the VEPTR system, 48% of children showed ossifications after 53 months. Ossifications were observed significantly more often in children with stiff deformities and after multiple surgical procedures. It is a much more common problem than previously thought. Level of Evidence: 3

7 December 2019 in BMC Musculoskeletal Disorders
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Journal Article
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AHAnna Kathrin Hell
Anna Kathrin Hell
LBLena Braunschweig
Lena Braunschweig
JBJennifer Behrend
Jennifer Behrend
HLHeiko M. Lorenz
Heiko M. Lorenz
KTKonstantinos Tsaknakis
Konstantinos Tsaknakis
KMKiril Mladenov
Kiril Mladenov
Background: Progressive Early-Onset Scoliosis (EOS) in children may lead to surgical interventions with growth-friendly implants, which require repeated lengthening procedures in order to allow adequate growth. Quality of life was studied using the validated German version of the EOS-Questionnaire (EOSQ-24-G) in surgically treated EOS children with different lengthening modalities. Methods: EOSQ-24-G and the KINDLR questionnaire were given to families with EOS children who had been treated by either vertical expandable prosthetic titanium rib implants and repetitive lengthening surgeries every 6 months or children who had received a magnetically expansion controlled implant, which was externally lengthened every 3 months. Results were compared according to differences between the two tests, and with possible influencing factors such as surgical method, severity of scoliosis, relative improvement of curvature, etiology, weight, age, travelling distance, complications, ambulatory ability and others. Results: 56 children with an average curve angle of 69° corrected to 33° (52%; average age 5.6 yrs) answered the EOSQ-24-G and the KINDLR after an average follow-up of 3.9 years. Health-related quality of life (HRQoL) was not affected by the initial scoliosis correction, the number of surgeries or the implant type. However, there was a negative correlation with non-ambulatory status, complications during treatment and for children with a neuromuscular scoliosis. Conclusion: Using the validated EOSQ-24-G, no statistically significant differences were found between the group of children receiving repetitive surgeries and children with external lengthening procedures without surgery. However, results were influenced by the etiology, complication rate or ambulatory ability. Level of Evidence/Clinical relevance: Therapeutic Level IV

28 November 2017 in JBJS Open Access
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Journal Article
Open access
HLHeiko M. Lorenz
Heiko M. Lorenz
BBBatoul Badwan
Batoul Badwan
MHMarina M. Hecker
Marina M. Hecker
KTKonstantinos Tsaknakis
Konstantinos Tsaknakis
KGKatharina Groenefeld
Katharina Groenefeld
AHAnna Kathrin Hell
Anna Kathrin Hell
Background: Children with severe spinal deformity frequently are managed with growth-friendly implants. After initial surgery, externally controlled magnetic rods allow spinal deformity correction during growth without further surgical intervention. The ability to lengthen the spine without additional surgical procedures is especially beneficial in high-risk children, such as those with spinal muscular atrophy (SMA). The purpose of the present study was to assess the level of control of spinal deformity in a homogeneous group of patients with SMA who were managed with magnetically controlled implants for 2 years. Methods: This prospective, nonrandomized study included 21 non-ambulatory children with type-II SMA and progressive scoliosis who were managed bilaterally with a magnetically controlled implant that was inserted parallel to the spine with use of rib-to-pelvis hook fixation. Radiographic measurements of scoliotic curves, kyphosis, lordosis, pelvic obliquity, and spinal length were performed before and after implantation of the magnetically controlled device and during external lengthening. The mean duration of follow-up was 2 years. Results: The mean main curve of patients without prior vertical expandable prosthetic titanium rib (VEPTR) treatment decreased from 70° before implantation of the magnetically controlled device to 30° after implantation of the device. Correction was maintained during the follow-up period, with a mean curve of 31° at the time of the latest follow-up at 2.2 years. Pelvic obliquity was surgically corrected by 76% (from 17° to 4°) and remained stable during follow-up. Thoracic kyphosis could not be corrected within the follow-up period. Spinal length of children without prior spinal surgery increased by >50 mm immediately after device implantation and steadily increased at a rate of 13.5 mm/yr over the course of treatment. During treatment, 4 general complications occurred and 6 lengthening procedures failed, with 3 patients requiring surgical revision. Conclusions: Bilateral implantation of an externally controlled magnetic rod with rib-to-pelvis fixation represents a safe and efficient method to control spinal deformity in children with SMA, achieving sufficient and stable curve correction as well as increased spinal length. The complication rate was lower than those that have been described for VEPTR and other growing rod instrumentation strategies. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

1 July 2018 in Clinical Spine Surgery
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Journal Article
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AHAnna Kathrin Hell
Anna Kathrin Hell
KGKatharina Dds Groenefeld
Katharina Dds Groenefeld
KTKonstantinos Tsaknakis
Konstantinos Tsaknakis
LBLena Braunschweig
Lena Braunschweig
HLHeiko M. Lorenz
Heiko M. Lorenz
Spine-based fixation of magnetically controlled lengthening devices has been successfully performed for children with early-onset scoliosis. However, spinal manipulation may lead to ossifications, stiffness, and autofusion as previously described. To avoid these problems, a surgical technique combining bilateral externally controlled magnetic device implantation with a rib cradle and pelvic hook fixation was introduced by us in 2011. By using a bilateral single-rib or double-rib cradle fixation and a pelvic hook, the magnetic device is percutaneously inserted. The spine corrects indirectly without further manipulation. In small rib diameter or severe osteoporosis, double-rib cradles are used. Our introduced technique enables modification of the rib vertebral angle, which may be beneficial in children with spinal muscular atrophy and rib-cage deformity. This nonrandomized prospective study describes 18 children with neuromuscular scoliosis treated first by this method. All patients followed the same protocol, with expansion procedures being performed 5 months after surgery and every 3 months thereafter. Clinical, radiologic, and complication data were analyzed, showing a significant reduction in scoliosis and pelvic obliquity and an increase in spinal length, which could be maintained over a follow-up period of 1.2 years. The overall complication rate was lower than previously described, with 8%, 2 of them requiring surgery.

1 September 2008 in Zeitschrift für Orthopädie und Unfallchirurgie
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AHAnna Kathrin Hell
Anna Kathrin Hell
JBJ. C. Becker
J. C. Becker
ORO. Rühmann
O. Rühmann
GLG. von Lewinski
G. von Lewinski
DLD. Lazovic
D. Lazovic
Studienziel: Erfassung von inter- und intraindividuellen Messabweichungen und der Lernkurve bei der sonografischen Auswertung der Säuglingshüften nach Graf. Material and Methode: 189 Teilnehmern von Grund-, Aufbau- und Abschlusskursen zum Erlernen der Säuglingshüftsonografie (DEGUM) wurden ein Fragebogen und jeweils 34 normale und pathologische Hüftsonogramme zur Auswertung nach der Methode von Graf vorgelegt. Sowohl Messabweichungen als auch die Lernkurve innerhalb der drei Kurse wurden bei den Teilnehmern ermittelt. Ergebnisse: Bei den Kursteilnehmern (n = 189) konnte sich die durchschnittliche Messabweichung von 6,74° (± 1,46°) im Grundkurs zu 6,22° (± 1,17°) im Aufbaukurs statistisch signifikant (p = 0,001) verkleinern. Die zusätzliche Absolvierung des Abschlusskurses (6,39° [± 1,70°]) erbrachte dagegen keine signifikant besseren Ergebnisse und somit keinen zusätzlich nachgewiesenen Lernerfolg. Die Bestimmung des Beta-Winkels zeigte größere Messabweichungen als die Bestimmung des Alpha-Winkels. Mit zunehmender Anzahl der von den Kursteilnehmern zwischen den Kursen durchgeführten Hüftsonografien zeigten sich signifikante Verbesserungen bei den Messungen. Pathologische Hüftsonogramme und Sonografien minderer Qualität führten zu signifikant erhöhten Messabweichungen. Schlussfolgerung: Es konnte nachgewiesen werden, dass zum Teil erhebliche inter- und intraindividuelle Messabweichungen während des Erlernens der Säuglingshüftsonografie in den Kursen auftreten. Dies war am deutlichsten bei der Messung des Beta-Winkels, bei pathologischen Hüftsonogrammen und bei der Auswertung von qualitativ schlechteren Sonogrammen. Die besten Ergebnisse wurden bei einer hohen Anzahl selbstständig durchgeführter Sonografien zwischen den Kursen erreicht. Für die Verbesserung der Messgenauigkeit scheint daher ein hoher Praxisanteil und ein gezieltes Training zur Beseitigung potenzieller Fehlerquellen von großer Bedeutung zu sein. Aim: Inter- and intraobserver reliability and learning curve using Graf's ultrasonographic hip examination were assessed. Material and Methods: 189 participants of the basic, advanced and final courses on hip ultrasound using the Graf method (DEGUM) were asked to answer a questionnaire and to measure 34 normal and pathological sonographic hip examinations. Measurement differences and the learning curve during the different courses were evaluated. Results: There was a significant (p = 0.001) improvement of the average angle between the basic (6.74° [± 1.46°]) and the advanced course (6.22° [± 1.17°]). However, there were no better results in the final course and no additional improvement. Participants had higher variations when measuring the beta-angle than the alpha-angle. A significant improvement was seen if the participants performed a large number of hip ultrasounds between the courses. Higher measurement differences were seen in pathological hip ultrasounds and in ultrasonographic examinations of poorer quality. Conclusions: During the educational courses on hip ultrasound using the Graf method, a high intra- and interobserver variability was seen. These findings were most prominent in measurement of the beta-angle, in pathological hip ultrasounds and in ultrasonographic hip examinations of poorer quality. The best results were achieved by participants who had performed a large number of examinations between courses. For the improvement of ultrasonographic measurements, a large number of self-performed examinations and a training in potential mistakes seem to be of great importance.

18 May 2022 in Osteoporosis International
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Journal Article
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KTKonstantinos Tsaknakis
Konstantinos Tsaknakis
KJKatharina Blanka Jäckle
Katharina Blanka Jäckle
KLK. A. Lüders
K. A. Lüders
HLH. M. Lorenz
H. M. Lorenz
LBL. Braunschweig
L. Braunschweig
AHAnna Kathrin Hell
Anna Kathrin Hell
Summary Duchenne muscular dystrophy is a progressive disease usually associated with loss of ambulation and progressive scoliosis. Immobilisation and glucocorticoid treatment are predisposing factors for reduced bone mineral density (BMD). Analysis of quantitative computed tomography revealed low BMD in thoracic and lumbar vertebrae in comparison to age- and sex-matched healthy controls. Introduction Evaluation of vertebral bone mineral density (BMD) in Duchenne Muscular Dystrophy (DMD) adolescents with untreated advanced scoliosis and comparison with the BMD values of healthy age-matched controls, based on quantitative computer tomography. Methods Thirty-seven DMD adolescents (age 15.6 ± 2.5 years) with spinal deformity were evaluated clinically and radiologically prior to definite spinal fusion and compared to 31 male and age-matched healthy individuals (age 15.7 ± 2.3 years). Data related to previous medical treatment, physiotherapy and ambulatory status was also analysed. Scoliotic curves were measured on plain sitting radiographs of the spine. The BMD Z-scores of the thoracic and lumbar vertebrae were calculated with QCTpro® (Mindways Software Inc., USA), based on data sets of preoperative, phantom pre-calibrated spinal computed tomography scans. Results A statistically significant lower BMD could be found in DMD adolescents, when compared to healthy controls, showing an average value for the lumbar spine of 80.5 ± 30.5 mg/cm3. Z-scores deteriorated from the upper thoracic towards the lower lumbar vertebrae. All but the uppermost thoracic vertebrae had reduced BMD values, with the thoracolumbar and lumbar region demonstrating the lowest BMD. No significant correlation was observed between BMD and the severity of the scoliotic curve, previous glucocorticoid treatment, cardiovascular impairment, vitamin D supplementation, non-invasive ventilation or physiotherapy. Conclusion DMD adolescents with scoliosis have strongly reduced BMD Z-scores, especially in the lumbar spine in comparison to healthy controls. These findings support the implementation of a standardised screening and treatment protocol. Level of evidence/clinical relevance: therapeutic level III