Klaus Lerch

Bacteria Ingestion by Blowfly Larvae: An in vitro Study

Background: Maggot debridement therapy is the medical use of live fly larvae for cleaning chronic and infected wounds, removing devitalized tissue and decreasing the risk of infection. Maggot-derived proteins are able to kill bacteria, and proteolytic enzymes are responsible for the liquefying of necrotic tissue. Objective: The aim of this study is to investigate bacterial ingestion by larvae roaming free on bacterial agar, compared to those larvae contained within vinyl bags. Methods: Free-roaming sterile larvae of Lucilia sericata and larvae contained in vinyl bags were fed on Escherichia coli producing green fluorescent protein (GFP). The time interval to the onset of fluorescent maggots was determined. At different time intervals, maggots were sacrificed, washed in sterile saline, sagittally cut in frozen sections and examined under a microscope with UV light. Results: After feeding on GFP-labelled E. coli, maggots roaming free on bacterial lawn agar demonstrated fluorescence after 3 min, maggots entrapped in vinyl bags after 25 min. In the sagittal frozen sections, the highest fluorescent intensity was detected in the larvae’s rostral part of the alimentary tract, the crop and the anterior midgut. Conclusion: In an in vitro setting, digestion and ingestion of whole or disintegrated bacteria is accomplished within minutes. The vinyl bag’s permeable membrane clearly causes a delay of this process.

Der navigationsgestützte bicondyläre Oberflächenersatz bei der sekundären Gonarthrose des RA-Patienten im Vergleich zur konventionellen Implantationstechnik

Zusammenfassung.Hintergrund:Die operative Therapie der sekundären Gonarthrose beim Patienten mit RA stellt erhebliche Anforderungen an den Operateur hinsichtlich der Komponentenausrichtung und des Weichteilbalancings. Da die Standzeit der Kniegelenkprothesen von der achsgenauen Implantationstechnik abhängt, sollte überprüft werden, inwieweit die CT-freie Navigation Vorteile im Vergleich zur konventionellen Technik bietet.Material und Methodik:In einer prospektiven Studie wurden je 40 Patienten mit einer sekundären Gonarthrose bei RA unter Verwendung der konventionellen Technik und eines CT-freien Navigationssystems mit demselben Prothesenmodell (PFC-Sigma® Depuy) versorgt. Die Beinachsen wurden prä- und postoperativ mit standardisierten Ganzbeinstandaufnahmen und ergänzenden seitlichen Aufnahmen vermessen.Ergebnisse:Ein achsgerechter Einbau mit einer maximalen Abweichung der Beinachse von 3° valgus bis 3° varus konnte bei 30 Patienten (75%) in der konventionell operierten Gruppe und bei 37 der navigierten Patienten (92,5%) erzielt werden.Diskussion:Die Verwendung des in dieser Studie benutzten Navigationssystems bietet dem Patienten die Voraussetzung für ein gutes Langzeitergebnis. Darüber hinaus bietet die Bandspannungsanalyse eine wichtige Hilfestellung bei der Versorgung der sekundären Gonarthrose. Schnittfehler können intraoperativ erkannt und korrigiert werden.Summary.Introduction:The operative treatment of a secondary gonarthrosis due to RA claims high quality in soft tissue balancing and accurate alignment in total knee arthroplasty (TKA) which are essential for good long-term results. The efficiency of an imageless computer-assisted implantation in TKA was evaluated and compared with conventional technique.Method:The authors implanted each 40 TKA either using the imageless computer-assisted or classical surgeon-controlled technique. The quality of implantation was studied on postoperative longleg coronal and lateral x-rays.Results:A postoperative leg axis between 3° varus and 3° valgus was obtained in 37 patients (92.5%) in the study group and 30 patients (75%) in the control group. Complications influencing the clinical outcome did not occur.Conclusion:The use of the imageless Vector-Vision navigation system provides the patient a good chance for longterm survival. Especially the ligament balancing tool appears to be useful. Cutting errors can be detected and intraoperatively corrected.

Navigated implantation of total knee endoprostheses in secondary knee osteoarthritis of rheumatoid arthritis patients as compared to conventional technique

Zusammenfassung.Hintergrund:Die operative Therapie der sekundären Gonarthrose beim Patienten mit RA stellt erhebliche Anforderungen an den Operateur hinsichtlich der Komponentenausrichtung und des Weichteilbalancings. Da die Standzeit der Kniegelenkprothesen von der achsgenauen Implantationstechnik abhängt, sollte überprüft werden, inwieweit die CT-freie Navigation Vorteile im Vergleich zur konventionellen Technik bietet.Material und Methodik:In einer prospektiven Studie wurden je 40 Patienten mit einer sekundären Gonarthrose bei RA unter Verwendung der konventionellen Technik und eines CT-freien Navigationssystems mit demselben Prothesenmodell (PFC-Sigma® Depuy) versorgt. Die Beinachsen wurden prä- und postoperativ mit standardisierten Ganzbeinstandaufnahmen und ergänzenden seitlichen Aufnahmen vermessen.Ergebnisse:Ein achsgerechter Einbau mit einer maximalen Abweichung der Beinachse von 3° valgus bis 3° varus konnte bei 30 Patienten (75%) in der konventionell operierten Gruppe und bei 37 der navigierten Patienten (92,5%) erzielt werden.Diskussion:Die Verwendung des in dieser Studie benutzten Navigationssystems bietet dem Patienten die Voraussetzung für ein gutes Langzeitergebnis. Darüber hinaus bietet die Bandspannungsanalyse eine wichtige Hilfestellung bei der Versorgung der sekundären Gonarthrose. Schnittfehler können intraoperativ erkannt und korrigiert werden.Summary.Introduction:The operative treatment of a secondary gonarthrosis due to RA claims high quality in soft tissue balancing and accurate alignment in total knee arthroplasty (TKA) which are essential for good long-term results. The efficiency of an imageless computer-assisted implantation in TKA was evaluated and compared with conventional technique.Method:The authors implanted each 40 TKA either using the imageless computer-assisted or classical surgeon-controlled technique. The quality of implantation was studied on postoperative longleg coronal and lateral x-rays.Results:A postoperative leg axis between 3° varus and 3° valgus was obtained in 37 patients (92.5%) in the study group and 30 patients (75%) in the control group. Complications influencing the clinical outcome did not occur.Conclusion:The use of the imageless Vector-Vision navigation system provides the patient a good chance for longterm survival. Especially the ligament balancing tool appears to be useful. Cutting errors can be detected and intraoperatively corrected.

Tissue concentrations of vancomycin and Moxifloxacin in periprosthetic infection in rats

Background A one-step exchange of an endoprosthesis with periprosthetic infection requires effective antibiotics at high concentrations around the endoprosthesis. We evaluated the tissue distribution of vancomycin and Moxifloxacin in a standardized in vivo model of periprosthetic infection. Methods 36 male rats with periprosthetic infection of the left hind leg, induced by a standardized procedure, received either antibiotic treatment with vancomycin or Moxifloxacin twice daily for 2 weeks, or a sham treatment. After the last administration, different tissues from each animal were evaluated for concentrations of antibiotic. Results Compared to plasma, the tissue concentrations of Moxifloxacin were higher in all tissues investigated (lung, muscle, fat, bone) and the tissue-plasma ratio of Moxifloxacin was considerably higher than that of vancomycin. The concentrations of Moxifloxacin were equally high in the infected and the uninfected hind leg, whereas the vancomycin concentrations were significantly higher in the infected leg. Interpretation The standardized model of periprosthetic infection described here can be extrapolated to different bacterial and mycotic pathogens, and also to different antibiotics or therapeutic regimes. It provides a way of correlating tissue concentrations with clinical outcome in future studies.

Moxifloxacin superior to vancomycin for treatment of bone infections--a study in rats.

Background Increasing resistance rates towards conventional antibiotics necessitate investigations of the efficacy of newly developed antibiotics. Thus, in a rat study, we compared the efficacy of moxifloxacin and vancomycin in the treatment of a local Staphylococcus aureus bone infection. Method The femoral medullary cavities of 36 Wistar rats were contaminated with 100 μL of an oxacillin-sensitive Staphylococcus aureus strain (ATCC 29213) at 108cfu/mL. On the seventh day, antibiotic treatment with moxifloxacin (10 mg/kg twice daily i.p.) or vancomycin (15 mg/kg twice daily i.p.) was commenced in 12 animals each. 12 control animals were left untreated. After 21 days, the infected femurs were explanted and the bacterial counts (cfu/g) were determined. Results In the control group, a median of 3.42 × 106cfu/g (LQ/UQ 1.09 × 106/ 1.55 × 107) was cultured, with a median of 2.53 × 106cfu/g (LQ/UQ 1.95 × 106/ 4.25 × 106) in the vancomycin group and a median of 2.49 × 105cfu/g (LQ/UQ 2.84 × 104/ 3.75 × 105) in the moxifloxacin group.The bacterial count was reduced by treatment with moxifloxacin both in comparison with the control group (p < 0.001), and in comparison with treatment with vancomycin (p < 0.001). There was no statistically significant difference between the vancomycin group and the control group (p = 0.53). Interpretation In contrast to vancomycin, moxifloxacin proved to be an effective antibiotic for the treatment of bone infections due to Staphylococcus aureus in our animal model.

Anpassungsformen des rheumatischen Karpus nach radiolunärer Arthrodese

Zusammenfassung.Ziel der Arbeit war, die radiologischen Anpassungsformen des Karpus im Langzeitverlauf nach radiolunärer Arthrodese zu untersuchen. Prä- und postoperative Röntgenbilder von 91 Handgelenken bei 78 Patienten mit rheumatoider Arthritis, die wegen einer karpalen Instabilität Instabilität eine radiolunäre Arthrodese erhielten, wurden hinsichtlich der Entwicklung des Mediokarpalgelenkes und des Larsen- Stadiums untersucht. Die Nachuntersuchungszeit betrug durchschnittlich 60 Monate. Nach radiolunärer Arthrodese bleibt das Mediokarpalgelenk zu 28% unverändert. In 35% kommt es zu einer Sekundärarthrose und in 37% zu einer Zunahme der arthritischen Veränderungen. Dies spiegelt sich auch in einer Zunahme des Larsen-Stadiums von durchschnittlich 3,2 auf 3,8 wider. Dennoch zeigt der Karpus erstaunliche Fähigkeiten zur Anpassung, indem er eine neue Gelenklinie entwickelt oder den mediokarpalen Gekenkspalt wieder aufbaut.Summary.Objective:The aim of this study was the analysis of long-term carpal changes after radiolunate arthrodesis.Methods:Pre- and postoperative X-rays of 91 wrists in 78 patients with rheumatoid arthritis, who were treated for carpal instability with a radiolunate arthrodesis, were examined concerning the midcarpal joint and the Larsen grade. The mean follow-up was 60 months.Results:After radiolunate arthrodesis the midcarpal joint space remained unchanged in 28%. In 35% secondary arthritis and in 37% further arthritic destruction occurred. The mean Larsen grade increased from 3.2 to 3.8. Six wrists needed complete arthrodesis 25 to 87 months after the primary procedure and one was treated by total wrist replacement. Adaptive changes of the carpus during progressive disease and in secondary arthritis were recognized. Three types of joint lines could be identified: in 35% of the wrists a “perilunar”, in 22% a “radio-midcarpal” and in 3% a purely “midcarpal” joint line. In 40% no specific joint line could be identified.Conclusion:After radiolunate arthrodesis the carpus remains unchanged in the long run in nearly a third of cases. But even if secondary arthritis or further arthritic destruction occurs as in the remaining cases, the carpus shows an amazing capacity for adaptation. A new intracarpal joint line may develop or the midcarpal joint re-establishes itself.

Sonographic evaluation of the elbow in rheumatoid arthritis: A classification of joint destruction

The purpose of this study was to evaluate and classify sonographically the joint damage of the elbow in patients with rheumatoid arthritis. Standardized sonography of the elbow joint was performed in patients with rheumatoid arthritis between 1998 and 2002; from 2000 onwards in a controlled and prospective study. A grading of the joint damage was developed, evaluated and compared with the radiographic standard reference films of the Larsen classification. A total of 320 consecutive patients were included in this study; 250 elbows of 125 patients (93 women/32 men) were examined in a prospective way. Mean age was 62.5 years and mean disease duration was 11.9 years. The sonographically visible changes could be divided into six stages. In 24% of the patients graded Larsen 0, sonography detected definite abnormalities classified as stages 1 to 3. Sonography is a valuable tool to assess and classify elbow joint alteration in rheumatoid arthritis. Particularly in early stages of joint affection, ultrasound (US) is superior to X-ray in detecting soft tissue changes and minor erosions.

Diagnose und Therapie der nekrotisierenden Fasziitis

ZusammenfassungDie nekrotisierende Fasziitis ist eine Weichteilinfektion mit einer Letalität von bis zu 80%. Die Infektion führt über einen Triggermechanismus zur Aktivierung von Interleukinen, Tumornekrosefaktor (TNF) α und γ-Interferon. Es resultiert eine kapilläre Thrombose mit Nekrose von Faszie, Kutis und Subkutis. Anamnestisch besteht oft ein auslösendes Ereignis in Form eines vorrausgegangenen Minimaltraumas oder operativen Eingriffs. Bei fulminantem Verlauf steht die Entwicklung einer Sepsis mit Multiorganversagen im Vordergrund. Die Diagnose wird in erster Linie klinisch aufgrund des Lokalbefunds und der raschen Progredienz gestellt und in Zusammenarbeit mit der Pathologie und der Mikrobiologie bestätigt.Hauptpfeiler der Therapie ist ein radikales chirurgisches Débridement innerhalb der ersten 24 h mit einer anschlieöenden intensivmedizinischen Überwachung. Wir haben zwischen Januar 1992 und März 2001 15 Patienten mit nekrotisierender Fasziitis therapiert. Die Letalität betrug 33%. Es zeigte sich eine deutliche Korrelation zwischen Risikofaktoren (86% der Patienten) und Morbidität. Diagnosestellung und Therapie sollten durch einen erfahrenen Chirurgen erfolgen. Innerhalb dieser Arbeit diskutieren wir die wichtigsten Kriterien zur Diagnosestellung und die therapeutischen Konsequenzen.AbstractNecrotizing fasciitis is a soft tissue infection with a lethality ranging up to 80%. Infection causes the activation of interleukin, tumor necrosis factor alpha, and gamma-interferon through a triggering mechanism. This results in a capillary thrombosis with necrosis of the fascia, cutis, and subcutis. The patients history often reveals a triggering event in the form of a recent minimal trauma or operative procedure. In a fulminant necrotizing fasciitis, the development of sepsis with consecutive multiple-organ failure mainly determines the outcome of the disease. Diagnosis is made initially upon clinical findings with a rapid progression of the disease and confirmed later by histologic and microbiologic findings.Radical surgical debridement within the first 24 h with postoperative treatment in an intensive care unit represents the cornerstone of therapy.Between January 1992 and March 2001, we treated 15 patients with necrotizing fasciitis. Lethality was 33%. There was a significant correlation between risk factors (present in 86% of the patients) and morbidity.Diagnosis and therapy should be performed by an experienced surgeon. In this contribution, we discuss the most important criteria that lead to the diagnosis and the therapeutic consequences.

Proposal for a sonographic classification of target joints in rheumatoid arthritis

ObjectiveThe purpose of this study was to classify sonographically the joint damage of target joints in patients with rheumatoid arthritis (RA).MethodsDuring a 3-year cross-sectional study, standardized arthrosonography of symptomatic target joints was performed in patients with RA. According to those findings, a classification with progressive deterioration of joint alteration in RA was created that grades visible morphological changes of the joint components. Using elbow joints as a subgroup, inter- and intraobserver reliability was calculated.ResultsExamined and included in this study were 1211 joints of 425 patients with RA. The mean disease activity score was 5.2 (range 0.75–7.79). Sonographically visible changes could be classified and divided into six stages. A standardized sonographic evaluation system was developed. In reference to the elbow joint, overall percentages for intra- and interobserver reliability of sonography were 90.8% and 88.8%, respectively.ConclusionSonography is a valuable tool for assessing and classifying joint alteration in RA. Particularly in early stages of joint affection, ultrasound is superior to X-ray in detecting soft tissue changes and minor erosions.

A comparison of two indices for ulnar translation and carpal height in the rheumatoid wrist

The indices for ulnar translation described by Chamay et al. (1983, Annales de Chirurgie de la Main, Vol. 2, pp. 5–17), and Bouman et al. (1994, Journal of Hand Surgery Vol. 19B, pp. 325–329), and for carpal height described by Youm et al. (1978, Journal of Bone and Joint Surgery, Vol. 40A, pp. 423–431) and Bouman et al. (1994) were compared in pre- and postoperative wrist X-rays of 91 patients with rheumatoid arthritis undergoing radiolunate arthrodesis. Both indices described by Bouman had a higher applicability and sensitivity than the Chamay and Youm indices and are recommended for use with the rheumatoid wrist. However false-negative values may result when the Bouman index for ulnar translation is used to follow up radiolunate arthrodesis.