Holger Bäthis

Navigation in total-knee arthroplasty: CT-based implantation compared with the conventional technique.

Background Exact axial limb alignment in total-knee arthroplasty (TKA) is important for a successful outcome. We evaluated the efficiency of computer-assisted implantation in TKA and compared it with the classical surgeon-controlled technique. Patients and methods We implanted 100 TKA using either the computer-assisted technique (50) or the conventional approach (50). There were no significant differences between the groups regarding the preoperative leg deformity. Accuracy of implantation was determined in postoperative long-leg coronal and lateral radiographs. Results A postoperative leg axis between 3° varus and 3° valgus was achieved in 46 patients in the group with computer-assisted implantation and 36 patients in the control group (p=0.01). A significant difference was also seen for the femoral component alignment in frontal plane. No complications influencing the clinical outcome were observed. Interpretation A CT-based navigation system improves the accuracy of TKA, but higher costs and time-consuming planning will mean that its usage is limited to special cases. Additional tools such as ligament balancing, which are presently only available with the CT-free software module, require to be added to the CT-based system.

CT-free computer-assisted total knee arthroplasty versus the conventional technique: radiographic results of 100 cases.

Computer-assisted total knee arthroplasty leads to better restoration of leg alignment and component orientation compared with the conventional technique.

The effect of femoral component rotation on patellar tracking in total knee arthroplasty

Rotational adjustment of the femoral component in total knee arthroplasty influences patellar tracking. Sixty patients underwent TKA; the femoral component was placed parallel to the epicondylar axis in 30 patients and the femoral component was placed in 3 degrees external rotation to the posterior condylar axis in 30 patients. The epicondylar axis was identified using an image-guided navigation system. Mean patellar shift was 2.65 degrees for the computer assisted group and 3.50 degrees for the control group. Mean patellar tilt was 4.88 degrees for the computer assisted group and 6.68 degrees for the control group. Aligning the femoral component parallel to the epicondylar axis leads to significantly better patellar tracking.

Bacterial contamination of open fractures - pathogens, antibiotic resistances and therapeutic regimes in four hospitals of the trauma network Cologne, Germany.

INTRODUCTION The bacterial contamination of soft tissues and bone in open fractures leads to an infection rate of up to 50%. Pathogens and their resistance against therapeutic agents change with time and vary in different regions. In this work, our aims were to characterize the bacterial spectrum present in open fractures, analyze the bacterial resistance to antibiotic agents and question the EAST guideline recommendations for antibiotic prophylaxis after open fractures in a German Trauma Network. MATERIALS AND METHODS We conducted a retrospective cohort study and included all patients with open fractures from 1(st) of January 2011 until the 31(st) of December 2014 in four hospitals of the trauma network cologne. Soft tissue damage was classified according to the Gustilo Anderson classification. RESULTS We included 123 patients. Forty-five injuries (37%) were classified I°, 45 (37%) as II° and 33 (27%) as III°. Lower leg (34%) was the most commonly injured location. An antibiotic prophylaxis was administered to 109 patients (89%). In 107 of them (98%) a cephalosporin or cephalosporin combination was given. In 35 of the patients (28%), microbiological samples were taken of the fracture site. Wound cultures were positive in 21 patients (60%). Fifty percent of the bacterial detections occurred in III° fractures. Coagulase negative Staphylococci (COST) were the most frequent pathogens. In II° open fractures one gram-negative strain was isolated. Fewest resistances were seen against quinolones and co-trimoxazole. DISCUSSION The recommended EAST guideline prophylaxis would have covered all but one bacterium (97% of positive cultures). One Escherichia coli was found in a II° open fracture and would have been missed. One of the isolated Staphylococci epidermidis and an Enterococcus faecium were resistant against gentamycin and first- and second-generation-cephalosporins which were used as prophylaxis frequently. However, a regional adaption of the EAST guidelines seems not justified due to the rather low number of cases in our study. CONCLUSION The EAST guideline seems to be adequate in a high percentage of cases (97%) in the setting of the trauma network cologne. Further research should be guided at identification of initial open fracture pathogens to improve the efficiency of antibiotic prophylaxis.

Computer-assisted cannulated screw fixation for slipped capital femoral epiphysis.

The goal of this study was to correlate radiographic measurements to the dynamic plantar pressure of the residual clubfoot. This was done by comparing radiographs and EMED plantar pressure results in 61 idiopathic clubfeet in 39 children at an average of 8 years after complete subtalar release. Radiographic measures were obtained using the standard method outlined by Simons, and pressure data were collected for eight regions of the foot. Pearson correlation analysis was performed and the most significant correlation was found between the calcaneal/first metatarsal angle in the lateral radiographic view (r = 0.72) and the midfoot contact area. In the anteroposterior view there was mild correlation between the talus/first metatarsal angle and both the peak pressure and plantar contact area. The results of this study indicate that radiographs used in concert with dynamic plantar pressure analysis will provide a more complete assessment of the corrected clubfoot.

[Soft tissue management in knees with varus deformity. Computer-assisted sequential medial ligament release].

ZusammenfassungHintergrundDie Varusgonarthrose mit Kontrakturen der Bänder und der dorsalen Kapsel erfordert ein sequenzielles Weichteilmanagement, um eine ausgeglichene Bandspannung in Flexion und Extension zu erreichen. Mit Einführung der Navigation in die Knieendoprothetik wird die Beinachse erstmals intraoperativ messbar.Methode10 Kniegelenke von Körperspendern wurden standardisiert navigationsgestützt (Ci®-Navigationssystem, DePuy® I-Orthopaedics®, München) operiert und die Veränderungen der Gesamtbeinachse und die Gap-Weite im Verlauf eines standardisierten medialen sequentiellen Bandreleases mit dem Navigationssystem dokumentiert.ErgebnisseJeder Releaseschritt führte zu einer statistisch signifikanten Veränderung der Beinachse und der Gap-Weite (p<0,001). Der größte Effekt wurde in Extension für den sog. kapsulären 6-cm-Release und den Release des medialen Kollateralbandes in 90° Flexion gesehen.SchlussfolgerungDie Navigation ermöglicht in der Knieendoprothetik die Visualisierung und Quantifizierung der einzelnen Releaseschritte und bietet eine wertvolle Hilfestellung.AbstractBackgroundKnees with severe varus deformities and contractures of the medial and lateral collateral ligaments and the posterior capsule require special soft tissue management to gain a stable knee over the full range of movement. The introduction of navigation systems into knee surgery has now made precise measurement of the leg axis and gap size possible.MethodsTen knee joints received a computer-assisted total knee replacement (Ci® navigation system DePuy® I-Orthopaedics®, Munich). The change of the leg axis and the size of the mediolateral gaps were measured and documented when performing a standardized medial ligament release sequence.ResultsWe found a significant effect after each release step regarding the change of the leg axis as well as the gap width (p<0.001). The highest effect was seen for the 6-cm capsule release in extension and the release of the medial collateral ligament in 90° flexion.ConclusionImplementation of computer-assisted navigation facilitates visualization and quantification of the effect of the sequential medial soft tissue release in total knee arthroplasty.

Weichteilmanagement bei der Varusgonarthrose@@@Soft tissue management in knees with varus deformity: Der navigationsgestützte schrittweise mediale Bandrelease@@@Computer-assisted sequential medial ligament release

ZusammenfassungHintergrundDie Varusgonarthrose mit Kontrakturen der Bänder und der dorsalen Kapsel erfordert ein sequenzielles Weichteilmanagement, um eine ausgeglichene Bandspannung in Flexion und Extension zu erreichen. Mit Einführung der Navigation in die Knieendoprothetik wird die Beinachse erstmals intraoperativ messbar.Methode10 Kniegelenke von Körperspendern wurden standardisiert navigationsgestützt (Ci®-Navigationssystem, DePuy® I-Orthopaedics®, München) operiert und die Veränderungen der Gesamtbeinachse und die Gap-Weite im Verlauf eines standardisierten medialen sequentiellen Bandreleases mit dem Navigationssystem dokumentiert.ErgebnisseJeder Releaseschritt führte zu einer statistisch signifikanten Veränderung der Beinachse und der Gap-Weite (p<0,001). Der größte Effekt wurde in Extension für den sog. kapsulären 6-cm-Release und den Release des medialen Kollateralbandes in 90° Flexion gesehen.SchlussfolgerungDie Navigation ermöglicht in der Knieendoprothetik die Visualisierung und Quantifizierung der einzelnen Releaseschritte und bietet eine wertvolle Hilfestellung.AbstractBackgroundKnees with severe varus deformities and contractures of the medial and lateral collateral ligaments and the posterior capsule require special soft tissue management to gain a stable knee over the full range of movement. The introduction of navigation systems into knee surgery has now made precise measurement of the leg axis and gap size possible.MethodsTen knee joints received a computer-assisted total knee replacement (Ci® navigation system DePuy® I-Orthopaedics®, Munich). The change of the leg axis and the size of the mediolateral gaps were measured and documented when performing a standardized medial ligament release sequence.ResultsWe found a significant effect after each release step regarding the change of the leg axis as well as the gap width (p<0.001). The highest effect was seen for the 6-cm capsule release in extension and the release of the medial collateral ligament in 90° flexion.ConclusionImplementation of computer-assisted navigation facilitates visualization and quantification of the effect of the sequential medial soft tissue release in total knee arthroplasty.

Weichteilmanagement bei der Varusgonarthrose

ZusammenfassungHintergrundDie Varusgonarthrose mit Kontrakturen der Bänder und der dorsalen Kapsel erfordert ein sequenzielles Weichteilmanagement, um eine ausgeglichene Bandspannung in Flexion und Extension zu erreichen. Mit Einführung der Navigation in die Knieendoprothetik wird die Beinachse erstmals intraoperativ messbar.Methode10 Kniegelenke von Körperspendern wurden standardisiert navigationsgestützt (Ci®-Navigationssystem, DePuy® I-Orthopaedics®, München) operiert und die Veränderungen der Gesamtbeinachse und die Gap-Weite im Verlauf eines standardisierten medialen sequentiellen Bandreleases mit dem Navigationssystem dokumentiert.ErgebnisseJeder Releaseschritt führte zu einer statistisch signifikanten Veränderung der Beinachse und der Gap-Weite (p<0,001). Der größte Effekt wurde in Extension für den sog. kapsulären 6-cm-Release und den Release des medialen Kollateralbandes in 90° Flexion gesehen.SchlussfolgerungDie Navigation ermöglicht in der Knieendoprothetik die Visualisierung und Quantifizierung der einzelnen Releaseschritte und bietet eine wertvolle Hilfestellung.AbstractBackgroundKnees with severe varus deformities and contractures of the medial and lateral collateral ligaments and the posterior capsule require special soft tissue management to gain a stable knee over the full range of movement. The introduction of navigation systems into knee surgery has now made precise measurement of the leg axis and gap size possible.MethodsTen knee joints received a computer-assisted total knee replacement (Ci® navigation system DePuy® I-Orthopaedics®, Munich). The change of the leg axis and the size of the mediolateral gaps were measured and documented when performing a standardized medial ligament release sequence.ResultsWe found a significant effect after each release step regarding the change of the leg axis as well as the gap width (p<0.001). The highest effect was seen for the 6-cm capsule release in extension and the release of the medial collateral ligament in 90° flexion.ConclusionImplementation of computer-assisted navigation facilitates visualization and quantification of the effect of the sequential medial soft tissue release in total knee arthroplasty.

Die dorsale karpometakarpale Luxation des 5. Strahls

ZusammenfassungEine dorsale Luxation im Karpometakarpalgelenk des 5. Strahls nach Trauma ist nicht häufig, in der Literatur sind nur 5 Fälle explizit beschrieben. Wir berichten über 2 Patienten, die sich eine traumatische Luxation im Karpometakarpalgelenk V zugezogen haben und geben einen Überblick über die vorliegende Literatur. Auf den Standardröntgenbildern (a.-p. und lateral) kann die Verletzung übersehen werden. Aus diesem Grund sollte beim Vorliegen entsprechender klinischer Symptome eine schräge Aufnahme (45 ° Pronationsstellung) zur Diagnosesicherung durchgeführt werden. Die anhand der Literatur empfohlene Therapie besteht in einer geschlossenen Reposition mit anschließender Kirschner-Draht-Fixierung und Gipsruhigstellung. Eine alleinige Reposition mit Gipsruhigstellung ohne Kirschner-Draht-Fixierung erscheint, selbst für die nach Reposition primär stabilen Verletzungen, weniger geeignet, da in der Literatur für diese Therapieform persistierende Schmerzen im Karpometakarpalgelenk V bei manueller Arbeit beschrieben worden sind. Bei unseren 2 Patienten bestand unmittelbar nach erfolgter Reposition eine Instabilität im Karpometakarpalgelenk V. Nach Kirschner-Draht-Fixierung und Gipsruhigstellung für 6 Wochen verfügten beide Patienten 3 Monate postoperativ über eine uneingeschränkte und schmerzfreie Beweglichkeit sowie einen kraftvollen Faustschluß im Karpometakarpalgelenk V.SummaryDorsal dislocation of the fifth carpometacarpal joint after injury is rare. Only five cases are reported in the literature. We report on two cases of dorsal dislocation of the fifth carpometacarpal joint after injury and we give a review of relatet literature. There are two interesting aspects concerning diagnostic and therapy of dorsal dislocation of the fifth carpometacarpal joint. Anteriorposterior and lateral radiographs do not always provide adequate visualisation of this joint so a dislocation may be misdiagnosed. A radiograph taken with the forearm pronated 45 degrees from the routine anteriorposterior position better shows the dislocation. The adequate therapy consists in closed reduction, Kirschner wire fixation and cast immobilisation. A reduction without following Kirschner wire fixation – even in those dislocations that were found to be stable after closed reduction – is not recommended because of the risk of persisting pain after heavy manual work. In our two cases an instability of the fifth carpometacarpal joint exsisted after closed reduction. After Kirschner wire fixation and cast immobilisation for 6 weeks both patients showed 3 months after operative therapy a full range of movement and a powerfull grip without any pain in the fifth carpometacarpal joint.

Reliable Alignment in Total Knee Arthroplasty by the Use of an iPod-Based Navigation System

Axial alignment is one of the main objectives in total knee arthroplasty (TKA). Computer-assisted surgery (CAS) is more accurate regarding limb alignment reconstruction compared to the conventional technique. The aim of this study was to analyse the precision of the innovative navigation system DASH® by Brainlab and to evaluate the reliability of intraoperatively acquired data. A retrospective analysis of 40 patients was performed, who underwent CAS TKA using the iPod-based navigation system DASH. Pre- and postoperative axial alignment were measured on standardized radiographs by two independent observers. These data were compared with the navigation data. Furthermore, interobserver reliability was measured. The duration of surgery was monitored. The mean difference between the preoperative mechanical axis by X-ray and the first intraoperatively measured limb axis by the navigation system was 2.4°. The postoperative X-rays showed a mean difference of 1.3° compared to the final navigation measurement. According to radiographic measurements, 88% of arthroplasties had a postoperative limb axis within ±3°. The mean additional time needed for navigation was 5 minutes. We could prove very good precision for the DASH system, which is comparable to established navigation devices with only negligible expenditure of time compared to conventional TKA.