Klinische Erfahrungen und Limitationen von Biopsien in verschiedenen Körperregionen mit einem robotischen Assistenzsystem in einem geschlossenen Magnetresonanztomographen

Zielsetzung dieser Arbeit ist die Vorstellung des klinischen Aufbaus und des Arbeitsablaufs eines robotischen Assistenzsystems für bildgeführte Interventionen in einem konventionellen Magnetresonanztomographen (MRT), sowie die Beurteilung der Genauigkeit und der klinischen Erfahrungen bei perkutanen Biopsien in verschieden Körperregionen. Material und Methoden: Das MR- kompatible, servopneumatische robotische Assistenzsystem lässt sich mit dem Patienten in die 60- cm Gantry eines Standard- MR- Scanners fahren. Die Genauigkeit des Systems wurde anhand von Nadelpunktionen (n= 25) in einem Phantommodell ermittelt. Perkutane diagnostische Biopsien wurden bei sechs Patienten durchgeführt. Ergebnisse: Für eine Interventionstiefe zwischen 29 und 95 mm wurde eine 3-DGenauigkeit von 2,2 +/- 0,7 mm (Intervall 0,9- 3,8 mm) bestimmt. Patienten mit einem BMI bis zu ≈30 kg/m2 konnten mit dem System punktiert werden. Die klinischen Arbeitsschritte werden anhand der Fallbeispiele dargestellt. Die mittlere Interventionszeit betrug 44 Minuten (Intervall 36 – 68 Minuten). Zusammenfassung: Die Punktion verschiedener Körperregionen ist mit Hilfe des robotischen Assistenzsystems in einem geschlossenen MRT erfolgreich und sicher möglich. Die Genauigkeit des Systems ist vergleichbar mit anderen Assistenzsystemen in der Literatur und genügt den klinischen Anforderungen. Eine kürzere Interventionszeit ist mittels einer Optimierung der einzelnen Arbeitsschritte möglich.:Einleitung 1 Publikation 5 Titelseite mit Abstract 6 Einleitung Publikation (Introduction) 7 Material und Methoden (Materials and Methods) 8 Robotisches Assistenzsystem (Robotic Assistance System) 8 Phantommessung (Phantom Experiment) 9 Patientenauswahlkriterien (Patient Selection Criteria) 11 Magnetresonanztomographie (MRI) 11 Biopsiedurchführung (Biopsy Procedure) 12 Ergebnisse (Results) 13 Phantommessung (Phantom Experiment) 13 Klinische Fälle (Clinical Experience) 14 Weichteilbiopsie kleines Becken (Soft-Tissue Biopsy in the Lesser Pelvis) 14 Weichteilbiopsie iliakaler Lymphknoten (Soft-Tissue Biopsy in Iliac Lymph Node) 15 Knochenbiopsie rechtes Femur (Bone Biopsy in Right Femur) 16 Knochenbiopsie Beckenkamm (Bone Biopsy in Iliac Crest) 17 Abszessaspiration (Abscess Aspiration) 18 Weichteilbiopsie Leber (Soft-Tissue Biopsy in the Liver) 19 Diskussion (Discussion) 22 Danksagungen (Acknowledgments) 25 Literaturverzeichnis Publikation (References) 25 Interpretation und Bewertung 30 Zusammenfassung 35 Literaturverzeichnis 39 Tabellenverzeichnis 46 Abbildungsverzeichnis 46 Erklärung über die eigenständige Abfassung der Arbeit 47 Lebenslauf und wissenschaftlicher Werdegang 48 Danksagung 49 Anlagen Anlage 1 Aufklärungsbogen zur Studie 50 Anlage 2 Einverständniserklärung 54 Anlage 3 Zertifikat des Assistenzsystems 57 durch TÜV- Sü

A cadaver‑based biomechanical model of acetabulum reaming for surgical virtual reality training simulators

Total hip arthroplasty (THA) is a highly successful surgical procedure, but complications remain, including aseptic loosening, early dislocation and misalignment. These may partly be related to lacking training opportunities for novices or those performing THA less frequently. A standardized training setting with realistic haptic feedback for THA does not exist to date. Virtual Reality (VR) may help establish THA training scenarios under standardized settings, morphology and material properties. This work summarizes the development and acquisition of mechanical properties on hip reaming, resulting in a tissue-based material model of the acetabulum for force feedback VR hip reaming simulators. With the given forces and torques occurring during the reaming, Cubic Hermite Spline interpolation seemed the most suitable approach to represent the nonlinear forcedisplacement behavior of the acetabular tissues over Cubic Splines. Further, Cubic Hermite Splines allowed for a rapid force feedback computation below the 1 ms hallmark. The Cubic Hermite Spline material model was implemented using a three-dimensional-sphere packing model. The resulting forces were delivered via a human–machine-interaction certified KUKA iiwa robotic arm used as a force feedback device. Consequently, this novel approach presents a concept to obtain mechanical data from high-force surgical interventions as baseline data for material models and biomechanical considerations; this will allow THA surgeons to train with a variety of machining hardness levels of acetabula for haptic VR acetabulum reaming

Klinische Erfahrungen und Limitationen von Biopsien in verschiedenen Körperregionen mit einem robotischen Assistenzsystem in einem geschlossenen Magnetresonanztomographen

Zielsetzung dieser Arbeit ist die Vorstellung des klinischen Aufbaus und des Arbeitsablaufs eines robotischen Assistenzsystems für bildgeführte Interventionen in einem konventionellen Magnetresonanztomographen (MRT), sowie die Beurteilung der Genauigkeit und der klinischen Erfahrungen bei perkutanen Biopsien in verschieden Körperregionen. Material und Methoden: Das MR- kompatible, servopneumatische robotische Assistenzsystem lässt sich mit dem Patienten in die 60- cm Gantry eines Standard- MR- Scanners fahren. Die Genauigkeit des Systems wurde anhand von Nadelpunktionen (n= 25) in einem Phantommodell ermittelt. Perkutane diagnostische Biopsien wurden bei sechs Patienten durchgeführt. Ergebnisse: Für eine Interventionstiefe zwischen 29 und 95 mm wurde eine 3-DGenauigkeit von 2,2 +/- 0,7 mm (Intervall 0,9- 3,8 mm) bestimmt. Patienten mit einem BMI bis zu ≈30 kg/m2 konnten mit dem System punktiert werden. Die klinischen Arbeitsschritte werden anhand der Fallbeispiele dargestellt. Die mittlere Interventionszeit betrug 44 Minuten (Intervall 36 – 68 Minuten). Zusammenfassung: Die Punktion verschiedener Körperregionen ist mit Hilfe des robotischen Assistenzsystems in einem geschlossenen MRT erfolgreich und sicher möglich. Die Genauigkeit des Systems ist vergleichbar mit anderen Assistenzsystemen in der Literatur und genügt den klinischen Anforderungen. Eine kürzere Interventionszeit ist mittels einer Optimierung der einzelnen Arbeitsschritte möglich.:Einleitung 1 Publikation 5 Titelseite mit Abstract 6 Einleitung Publikation (Introduction) 7 Material und Methoden (Materials and Methods) 8 Robotisches Assistenzsystem (Robotic Assistance System) 8 Phantommessung (Phantom Experiment) 9 Patientenauswahlkriterien (Patient Selection Criteria) 11 Magnetresonanztomographie (MRI) 11 Biopsiedurchführung (Biopsy Procedure) 12 Ergebnisse (Results) 13 Phantommessung (Phantom Experiment) 13 Klinische Fälle (Clinical Experience) 14 Weichteilbiopsie kleines Becken (Soft-Tissue Biopsy in the Lesser Pelvis) 14 Weichteilbiopsie iliakaler Lymphknoten (Soft-Tissue Biopsy in Iliac Lymph Node) 15 Knochenbiopsie rechtes Femur (Bone Biopsy in Right Femur) 16 Knochenbiopsie Beckenkamm (Bone Biopsy in Iliac Crest) 17 Abszessaspiration (Abscess Aspiration) 18 Weichteilbiopsie Leber (Soft-Tissue Biopsy in the Liver) 19 Diskussion (Discussion) 22 Danksagungen (Acknowledgments) 25 Literaturverzeichnis Publikation (References) 25 Interpretation und Bewertung 30 Zusammenfassung 35 Literaturverzeichnis 39 Tabellenverzeichnis 46 Abbildungsverzeichnis 46 Erklärung über die eigenständige Abfassung der Arbeit 47 Lebenslauf und wissenschaftlicher Werdegang 48 Danksagung 49 Anlagen Anlage 1 Aufklärungsbogen zur Studie 50 Anlage 2 Einverständniserklärung 54 Anlage 3 Zertifikat des Assistenzsystems 57 durch TÜV- Sü

Klinische Erfahrungen und Limitationen von Biopsien in verschiedenen Körperregionen mit einem robotischen Assistenzsystem in einem geschlossenen Magnetresonanztomographen

Zielsetzung dieser Arbeit ist die Vorstellung des klinischen Aufbaus und des Arbeitsablaufs eines robotischen Assistenzsystems für bildgeführte Interventionen in einem konventionellen Magnetresonanztomographen (MRT), sowie die Beurteilung der Genauigkeit und der klinischen Erfahrungen bei perkutanen Biopsien in verschieden Körperregionen. Material und Methoden: Das MR- kompatible, servopneumatische robotische Assistenzsystem lässt sich mit dem Patienten in die 60- cm Gantry eines Standard- MR- Scanners fahren. Die Genauigkeit des Systems wurde anhand von Nadelpunktionen (n= 25) in einem Phantommodell ermittelt. Perkutane diagnostische Biopsien wurden bei sechs Patienten durchgeführt. Ergebnisse: Für eine Interventionstiefe zwischen 29 und 95 mm wurde eine 3-DGenauigkeit von 2,2 +/- 0,7 mm (Intervall 0,9- 3,8 mm) bestimmt. Patienten mit einem BMI bis zu ≈30 kg/m2 konnten mit dem System punktiert werden. Die klinischen Arbeitsschritte werden anhand der Fallbeispiele dargestellt. Die mittlere Interventionszeit betrug 44 Minuten (Intervall 36 – 68 Minuten). Zusammenfassung: Die Punktion verschiedener Körperregionen ist mit Hilfe des robotischen Assistenzsystems in einem geschlossenen MRT erfolgreich und sicher möglich. Die Genauigkeit des Systems ist vergleichbar mit anderen Assistenzsystemen in der Literatur und genügt den klinischen Anforderungen. Eine kürzere Interventionszeit ist mittels einer Optimierung der einzelnen Arbeitsschritte möglich.:Einleitung 1 Publikation 5 Titelseite mit Abstract 6 Einleitung Publikation (Introduction) 7 Material und Methoden (Materials and Methods) 8 Robotisches Assistenzsystem (Robotic Assistance System) 8 Phantommessung (Phantom Experiment) 9 Patientenauswahlkriterien (Patient Selection Criteria) 11 Magnetresonanztomographie (MRI) 11 Biopsiedurchführung (Biopsy Procedure) 12 Ergebnisse (Results) 13 Phantommessung (Phantom Experiment) 13 Klinische Fälle (Clinical Experience) 14 Weichteilbiopsie kleines Becken (Soft-Tissue Biopsy in the Lesser Pelvis) 14 Weichteilbiopsie iliakaler Lymphknoten (Soft-Tissue Biopsy in Iliac Lymph Node) 15 Knochenbiopsie rechtes Femur (Bone Biopsy in Right Femur) 16 Knochenbiopsie Beckenkamm (Bone Biopsy in Iliac Crest) 17 Abszessaspiration (Abscess Aspiration) 18 Weichteilbiopsie Leber (Soft-Tissue Biopsy in the Liver) 19 Diskussion (Discussion) 22 Danksagungen (Acknowledgments) 25 Literaturverzeichnis Publikation (References) 25 Interpretation und Bewertung 30 Zusammenfassung 35 Literaturverzeichnis 39 Tabellenverzeichnis 46 Abbildungsverzeichnis 46 Erklärung über die eigenständige Abfassung der Arbeit 47 Lebenslauf und wissenschaftlicher Werdegang 48 Danksagung 49 Anlagen Anlage 1 Aufklärungsbogen zur Studie 50 Anlage 2 Einverständniserklärung 54 Anlage 3 Zertifikat des Assistenzsystems 57 durch TÜV- Sü

Biomechanical testing of different fixation techniques for intraoperative proximal femur fractures: a technical note

ABSTRACTIntraoperative proximal femoral fractures (IPFF) represent a rare but challenging complication of total hip arthroplasties. They usually occur as a longitudinal split. This pilot trial aimed to compare the biomechanical primary stability of different fixation techniques for IPFF. Standardised longitudinal medial split fractures of the proximal femur (type II, Modified Mallory Classification) were created in artificial osteoporotic and non-osteoporotic composite femora after implantation of a cementless femoral stem. Five different fixation techniques were compared: cerclage band, cerclage wiring with one or two wires, and lag screw fixation with one or two lag screws. A quasi-static loading protocol was applied and failure loads were evaluated. The observed median failure loads were 4192N (3982N – 5189N) for one cerclage band, 4450N (3577N – 4927N) for one cerclage wire, 5016N (4175N – 5685N) for two cerclage wires, 6085N (5000N – 8907N) for one lag screw, and 4774N (4509N – 8502N) for two lag screws. Due to the wide range of failure loads within the experimental groups, there were no observable differences between the groups. All fixation techniques provided sufficient primary stability in osteoporotic and non-osteoporotic composite bones. Further cadaveric studies with larger sample sizes may be needed to confirm the results presented here

Silver-coated modular Megaendoprostheses in salvage revision arthroplasty after periimplant infection with extensive bone loss – a pilot study of 34 patients

Abstract Background Hip and knee replacements in patients with bone defects after infection correlates with high rates of reinfection. In this vulnerable patient population, the prevention of reinfection is to be considered superordinate to the functionality and defect bridging. The use of silver coating of aseptic implants as an infection prophylaxis is already proven; however, the significance of these coatings in septic reimplantation of large implants is still not sufficiently investigated. Methods In a retrospective analysis, 34 patients who have been treated with a modular mega-endoprosthesis after a cured bone infection of the lower limb (femur or tibia) have been evaluated. One group with 14 patients (NSCG: non silver- coated group) was supplied with the non silver- coated implants: MML München- Lübeck™ modular endoprosthesis system (AQ Implants, Ahrensburg, Germany) or MUTARS® Modular Universal Tumor And Revision System (Implantcast GmbH, Buxtehude, Germany). The other group with 20 patients (SCG: silver- coated group) was supplied with the silver- coated system of MUTARS®. In addition to the clinical findings and the patients’ histories, specifically the reinfection rates, the patients’ mobility was assessed using the New Mobility Score (NMS, by Parker and Palmer). Results The median follow-up period was 72 months, ranging from 6 to 267 months. The dropout rate was 5.8%. The reinfection rate after healed reinfection in SCG was 40% (8/20), in NSCG 57% (8/14), p = 0.34; α =0.05. The time for reinfection was, on average, 14 months (1–72 months) in SCG and 8 months (1–48 months) in the NSCG (p = 0.61; α =0.05). The two groups showed no differences in the NMS. Conclusion With this retrospective analysis, it can be determined that the rate of reinfection of modular mega-endoprostheses on the hip and knee joint after healed periprosthetic joint infection (PJI) can be reduced by the use of silver coated implants. The time until reinfection can also be delayed by utilizing silver coated implants. Due to the low number of cases of this highly specific patient population, no statistical significance could be determined. A positive effect, however, can be assumed through the use of silver coatings in mega-endoprostheses after an infectious situation

The impact of capsular repair on the risk for dislocation after revision total hip arthroplasty – a retrospective cohort-study of 259 cases

Abstract Background Dislocation following total hip arthroplasty has to date not been resolved satisfactorily. Previous work has shown that using a less-invasive adaption of Bauer’s lateral transgluteal approach with capsular repair significantly reduces dislocation rates in primary total hip arthroplasty. The aim of this retrospective cohort study was to assess whether this approach also helps to reduce the dislocation rate in revision total hip arthroplasty. Methods We analyzed revision total hip arthroplasty cases performed between 10/2005 and 12/2013 in our department, classifying capsular repair cases as study group and capsular resection cases as control group. The WOMAC score, the dislocations and the revisions were observed. Results A total of 259 cases were included, 100 in the study group and 159 in the control group. In the 12-month follow-up, dislocation rates were significantly lower in the study group (3%, n = 3) compared to the control group (21.4%, n = 34; p = 0.001). Overall follow-up periods were 49 and 79 months, revision frequencies were 10 and 29%, pain improvements were 5.5 compared to 4.4 and the WOMAC global scores averaged 2.0 ± 2.1 and 2.9 ± 2.6 for the study group and the control group, respectively. Conclusion The modified, less-invasive, lateral transgluteal approach with capsular repair was accompanied by an 86% reduction in dislocation rates when compared to the conventional technique with capsular resection via the anterolateral Watson-Jones-approach. Capsular repair is possible in about 60% of the revision total hip arthroplasty cases, may be considered as beneficial to avoid dislocation and can therefore be recommended

Treatment of genu valgum in children by means of temporary hemiepiphysiodesis using eight-plates: short-term findings

Abstract Background Idiopathic genu valgum is a frequently diagnosed growth disorder in adolescence. Whenever the possibilities of conservative therapy have been exhausted, leg straightening by means of hemiepiphysiodesis has become the standard form of treatment. Because of their flexible screw-plate connection, eight-Plates have been reported in the literature to lead to lower complications regarding implant loosening and fracture compared to other implants. The aim of this retrospective survey was to analyse our own patient population who were treated for genu valgum by means of temporary hemiepiphysiodesis near the knee using eight-Plates to modulate growth. Methods Between July 2007 and July 2015, 198 eight-Plates were implanted near the knee in 132 children suffering from genu valgum to modulate growth. Depending on the deformity analysis, an eight-Plate was implanted on the distal medial femur and/or the proximal medial tibia. By December 2015, they had been removed from 105 patients. The etiology of genu valgum was mainly idiopathic or associated withobesity. Evaluation was carried out clinically and radiologically (whole-leg X-ray in standing) including determination of the joint angles. Results The median follow-up period was about 46 months (12–102 months). The median age at implantation was 12.7 +/−6.76 years. Of the 105 patients, 45.7% (n = 48) were girls. The eight-Plates remained in place for a median period of 13 +/−1.76 months. Irrespective of the location of hemiepiphysiodesis, the intermalleolar distance was corrected to a median of 0 +/−2.1 cm while the anatomical femorotibial angle was corrected by on average 9 +/−2.7 °Mechanical lateral distal femoral angle changed an average 7 +/− 7.72 degrees. Medial proximal tibial angle changed an average 4 +/− 6.02 degrees. Complications necessitating surgery occurred in 2.8% of cases (1 wound infection, 3 corrective osteotomies following overcorrection). Conclusion Temporary hemiepiphysiodesis using eight-Plates is a gentle, simple and effective procedure used to treat genu valgum by modulating growth. Slight overcorrection is desirable due to the rebound phenomenon, especially in young patients with high growth potential and risk groups such as obese children. In adolescents with only low growth potential (older than 14 years), owing to the low correction potential, the indication should be strictly reviewed and the possible failure of therapy should be discussed with the patient. No differences were observed regarding the location of the implanted eight-Plates (femoral or tibial)

Bipolar hip arthroplasty as salvage treatment for loosening of the acetabular cup with significant bone defects

Introduction: Revision arthroplasty of the hip is becoming increasingly important in recent years. Early primary arthroplasty and longer life expectancy of the patients increases the number of revision surgery. Revision surgery of hip arthroplasty is major surgery for the patients, especially the elderly, with significant risks concerning the general condition of the patient. The aim of this work is to evaluate the outcome of bipolar hip arthroplasty as a salvage procedure for treatment of loosening of the acetabular cup with significant acetabular bone defects after total hip replacement (THR) in multi-morbid patients.Patients and methods: During the period from January 1 2007 to December 31 2011 19 revision hip surgeries were performed in , in which the loosened acetabular cup was replaced by a bipolar head. The examined patient group consisted exclusively of female patients with an average of 75 years. The predominant diagnosis was “aseptic loosening” (84.2%). All patients in our study were multi-morbid. We decided to resort to bipolar hip arthroplasty due to the compromised general condition of patients and the major acetabular bone defects, which were confirmed intraoperatively. The postoperative follow-up ranged from 0.5 to 67 months (average 19.1 months). Results: Evaluation of the modified Harris Hip Score showed an overall improvement of the function of the hip joint after surgery of approximately 45%.Surgery was less time consuming and thus adequate for patients with significantly poor general health condition. We noticed different complications in a significant amount of patients (68.4%). The most common complication encountered was the proximal migration of the bipolar head.The rate of revision following the use of bipolar hip arthroplasty in revision surgery of the hip in our patients was high (21%). Despite the high number of complications reported in our study, we have noticed significant improvement of hip joint function as well as subjective pain relief in the majority of patients. We clearly achieved clinically satisfactory results in 14 patients.Conclusion: Bipolar hip arthroplasty is by no means to be regarded as standard procedure in revision surgery of THR. It provides an option or salvage procedure for patients with poor general condition in whom the quickest possible surgical intervention preserving mobility is required. This is particularly true for multi-morbid patients in whom sufficient acetabular fixation is not possible