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[show abstract]
[hide abstract]
ABSTRACT: Operationsziel
Knochenschonender künstlicher Hüftgelenkersatz für den jungen und aktiven Patienten über einen weichteilschonenden, modifizierten
transglutealen, lateralen Zugang.
Indikationen
Primäre Koxarthrose bei sportlich aktiven, im Berufsleben stehenden Patienten im Alter von < 65 Jahren (Männer) und < 60 Jahren
(Frauen).
Gute Knochenqualität.
Kontraindikationen
Männliche Patienten ≥ 65 Jahre, weibliche Patienten ≥ 60 Jahre.
Femurkopfnekrose.
Varischer Schenkelhals mit reduziertem horizontalen femoralen Offset.
Femurkopfzysten (> 1 cm Durchmesser).
Infektion.
Osteoporose.
Rheumatoide Arthritis.
Tumor.
Eingeschränkte Nierenfunktion.
Beinlängendifferenz (≥ 1 cm).
Metallallergie.
Stattgehabte Schenkelhalsfraktur.
Stattgehabte intertrochantäre Umstellungsosteotomien.
Operationstechnik
Rückenlagerung des Patienten. Modifizierter transglutealer, lateraler Zugang zum Hüftgelenk. Luxation des Hüftkopfes. Zur
verbesserten Pfannenübersicht primär Bearbeitung des Femurkopfes. Zentrierte Ausrichtung des zentralen Führungsdrahts im Schenkelhals
in einer leichten Valgusposition von ca. +5° zum anatomischen Centrum-Collum-Diaphysen- (CCD-)Winkel mit dem mechanischen
Zielinstrumentarium. Überbohren des zentralen Führungsdrahts bis zu der für das Implantat geeigneten Tiefe. Einbringen des
zentralen Führungsstabs. Präparation des Femurkopfes über den zentralen Führungsstab durch Zylinderfräsung eine bis zwei Fräsgrößen
größer als die kleinstmögliche zu implantierende femorale Komponente. Zementfreie Implantation der azetabulären Komponente
entsprechend der zuvor bestimmten definitiven Größe der femoralen Komponente. Definitive Zylinder-, Plan- und Facettenfräsung
des Femurkopfes. Nach zementierter Implantation der femoralen Komponente Gelenkreposition und Beenden der Operation.
Weiterbehandlung
Mobilisation an zwei Unterarmgehstützen ab dem 1. postoperativen Tag. Entfernen der Redon-Drainagen nach 24 h. Teilbelastung
mit 20 kg für 3 Wochen unter Fortführung der Thromboseprophylaxe. Limitation der Hüftflexion auf 90° in den ersten 6 postoperativen
Wochen sowie Verbot der Adduktion und der forcierten Außenrotation zum Luxationsschutz. Vermeidung von Sportarten mit Sprungund
axialen Stoßbelastungen für 12 Monate postoperativ.
Ergebnisse
Ausgewertet wurden die prä- und die postoperative Funktion von 72 Patienten mit 82 Prothesen und einer mittleren Standzeit
von 29,2 ± 11 Monaten mit Hilfe des Harris- Hip-Scores (HHS), des modifizierten Aktivitätsindexes nach UCLA (University of
California, Los Angeles) und des Merled’Aubigné- Scores. Radiologisch wurden postoperativ der Prothesenwinkel und das femorale
Offset sowie periprothetische Lockerungszeichen/Lysesäume beurteilt und mit dem präoperativen CCD-Winkel sowie dem femoralen
Offset verglichen. Bei der Nachuntersuchung fand sich im Vergleich zur präoperativen Bewertung eine signifikante Steigerung
der durchschnittlichen Werte des HHS (94 ± 4,6 vs. 40,1 ± 7 Punkte), des modifizierten UCLA-Aktivitätsindexes (8,9 ± 2,6 vs.
4,6 ± 2,2) und des Merle-d’Aubigné-Scores (17,9 ± 1,9 vs. 7,3 ± 2,4 Punkte; p ≤ 0,05). In 98,8% zeigte sich eine feste Osteointegration
der Pfannen- und Femurkomponenten. Die Abweichung des physiologischen CCD-Winkel (136,6° ± 3,6°) zum postoperativen Prothesenwinkel
(142,6° ± 4,9°) betrug 6° ± 2,8°. Das postoperative femorale Offset war gegenüber dem präoperativen Offset im Mittel um 2,3
mm reduziert. Im klinischen Nachuntersuchungszeitraum erforderten n = 2 Prothesen (2,5%) eine operative Revision (eine Schenkelhalsfraktur;
eine periartikuläre Ossifikation [Brooker III]).
Objective
Objective Bone-preserving hip resurfacing in young and active patients using a soft-tissue-sparing, modified transgluteal,
lateral approach.
Indications
Primary hip osteoarthritis in physically active, working patients aged < 65 years (males) and < 60 years (females). Good bone
quality.
Contraindications
Male patients ≥ 65 years of age, female patients ≥ 60 years of age.
Necrosis of the femoral head.
Varus deformity of the femoral neck with a reduced horizontal femoral offset.
Femoral head cysts (> 1 cm in diameter).
Infection.
Osteoporosis.
Rheumatoid arthritis. Tumor. Reduced renal function.
Leg length difference (≥ 1 cm). Metal allergy.
Previous femoral neck fracture.
Previous intertrochanteric femoral osteotomies.
Surgical Technique
Supine position of the patient. Modified transgluteal, lateral approach to the hip joint. Luxation of the femoral head. First,
reaming of the femoral head to improve visualization of the acetabular cup. Central positioning of the guide wire in the femoral
neck in a slight valgus position of approximately +5° to the anatomic collodiaphyseal (CCD) angle using the mechanical targeting
device. Overdrilling of the central guide wire to the appropriate depth for the implant. Central insertion of the guide rod.
Preparation of the femoral head over the guide rod using cylinder cutters one or two sizes larger than the smallest possible
femoral component. Cement-free implantation of the acetabular component according to the predetermined definitive size of
the femoral component. Final preparation of the femoral head using profile, surface and forming cutter. Following cemented
implantation of the femoral component, repositioning of the hip joint and conclusion of the surgical procedure.
Postoperative Management
Mobilization of the patient using two forearm crutches as of the 1st day after surgery. Removal of the Redon drains after
24 h. Partial weight bearing of 20 kg for 3 weeks under continuation of thrombosis prophylaxis. Limitation of hip flexion
to 90° during the first 6 postoperative weeks, and no adduction and forced external rotation allowed in order to avoid luxation.
Avoidance of sports involving the loads of jumping and axial impact loading for 12 postoperative months.
Results
Analysis involved the pre- and postoperative functions of 72 patients with a total of 82 prostheses and a mean durability
time of 29.2 ± 11 months based on the Harris Hip Score (HHS), the modified UCLA (University of California, Los Angeles) activity
index, and the Merle d’Aubigné Score. Postoperatively, prosthetic angle and femoral offset as well as periprosthetic signs
of loosening/lytic areas were assessed by means of radiology and compared with the preoperative CCD angle and femoral offset.
Compared to the preoperative evaluation, follow-up yielded a significant increase in the average HHS values (94 ± 4.6 vs.
40.1 ± 7 points), the modified UCLA activity index (8.9 ± 2.6 vs. 4.6 ± 2.2), and the Merle d’Aubigné Score (17.9 ± 1.9 vs.
7.3 ± 2.4; p ≤ 0.05). In 98.8%, a solid osteointegration of the cup and femoral components was observed. The average deviation
of the physiological CCD angle (136.6° ± 3.6°) from the postoperative angle of the prosthesis (142.6° ± 4.9°) was 6° ± 2.8°.
The postoperative femoral offset was reduced by an average of 2.3 mm compared to the preoperative offset. During clinical
follow-up n = 2 prostheses (2.5%) required revision (one femoral neck fracture; one periarticular ossification [Brooker III]).
Operative Orthopädie und Traumatologie 04/2012; 21(6):586-601. · 0.46 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Operationsziel
Wiederherstellung eines schmerzfrei belastbaren Hüftgelenks mit einem zementfrei implantierten, rotationsstabilen, diaphysär
verankerten modularen Revisionsschaft.
Indikationen
Prothesenschaftlockerungen mit osteolytischen Knochendefekten (Defektklassifikation nach Paprosky Typ I–III). Materialversagen
mit Prothesenbruch.
Sub- und/oder periprothetische Femurfrakturen.
Tumoren.
Kontraindikationen
Ausgedehnte Osteolysen, die eine diaphysäre Prothesenverankerung nicht erlauben.
Operationstechnik
Transglutealer Zugang zum Hüftgelenk. Entfernen des gelockerten Prothesenschafts und — im zementierten Fall — des Knochenzements.
Entfernen des intramedullären Granulationsgewebes. Aufbohren des Markraums mit flexiblen Bohrwellen und formschlüssige, zementfreie
Implantation des sternförmigen modularen Revisionsschaftes mit diaphysärem „Press-fit‘ Bei ausgedehntem metaphysären Knochendefekt
Augmentation mit autogenem/allogenem Knochen.
Weiterbehandlung
Mobilisation an zwei Unterarmgehstützen ab dem 1. postoperativen Tag. Entfernen der einliegenden Redon-Drainagen nach 48 h.
Teilbelastung mit 20 kg für 6 Wochen postoperativ. Bei nativradiologisch unverändertem Prothesensitz nach 6 Wochen Steigerung
der Belastung um wöchentlich 10 kg bis zur Vollbelastung unter Fortführen der Thromboseprophylaxe. Röntgenkontrollen im weiteren
Verlauf nach 3, 6 und 12 Monaten. Anschließend jährliche Verlaufskontrolle.
Ergebnisse
Untersucht wurden 45 Patienten (n = 48 Prothesen) mit einem durchschnittlichen Lebensalter von 67,2 Jahren (min.–max. 42,4–87,4
Jahre). Die mittlere Prothesenstandzeit der Modularen Revisions Prothese MRP-TITAN-Revisionsschaft betrug 4,7 Jahre (min.–max. 1,0–9,0 Jahre). Der Harris-Hip-Score — differenziert nach den
Knochendefekttypen Paprosky I–III — stieg von 25,6 präoperativ auf 71,4 postoperativ zum Zeitpunkt der letzten Nachuntersuchung
(≤0,05). 32 Patienten wiesen präoperativ einen ausgedehnten knöchernen Defekt auf (≥Paprosky IIB). 44 Patienten zeigten nativradiologisch
eine stabile Verankerung ohne Migration. In einem Fall wurde der Schaft (Standzeit 2,36 Jahre) bei zunehmendem axialen Einsinken
(≥5 mm) gewechselt. Bei allen Patienten mit Knochentransplantation (n = 30) zeigte sich ein guter Transplantateinbau mit konsekutiver
Defektregeneration. Bei sechs Patienten kam es zu postoperativen Luxationen mit nachfolgender viermaliger geschlossener Reposition.
Bei zwei Patienten wurde offen reponiert und der Antetorsionswinkel des Prothesenhalses ohne Ausbau der distal verankerten
Prothesenschaftkomponente korrigiert. Mechanische Versagerquote im 9-Jahres-Nachuntersuchungszeitraum: eine von 48 prospektiv
untersuchten Prothesen. Überlebensrate nach Kaplan-Meier 97%.
Objective
Restoration of a painless hip joint capable of bearing weight by uncemented implantation of a rotationally stable, modular
revision stem anchored in the diaphysis.
Indications
Prosthetic stem loosening with osteolytic bone defects (defect classification types I–III according to Paprosky). Material
failure with broken prosthesis.
Sub- and/or periprosthetic femoral fractures.
Tumors.
Contraindications
Extensive osteolysis preventing diaphyseal anchorage of the prosthesis.
Surgical Technique
Transgluteal approach to the hip joint. Removal of the loose prosthetic stem and, if cemented, the bone cement as well. Excision
of intramedullary granulation tissue. Reaming of the medullary cavity with flexible reaming shafts and form-fit, uncemented
implantation of the star-shaped modular revision stem with diaphyseal press fit. If there is extensive loss of metaphyseal
bone stock, augmentation with autogenous/allogenic bone should be performed.
Postoperative Management
Mobilization on two underarm crutches from the 1st postoperative day. Removal of the Redon drains after 48 h. Partial loading
with 20 kg for 6 weeks postoperatively. If plain radiographs show unchanged seating of the prosthesis after 6 weeks, loading
can be increased by 10 kg per week until full weight bearing is achieved; thrombosis prophylaxis is continued throughout.
Radiologic checkups after 3, 6, and 12 months. After that, the patient should be checked annually.
Results
45 patients (n = 48 prostheses) with an average age of 67.2 years (min.–max. 42.4–87.4 years) were investigated. The average
implantation time of the Modular Revision Prosthesis MRP-TITAN revision stem was 4.7 years (min.–max. 1.0–9.0 years). The Harris Hip Score for Paprosky bone defect types
I–III had increased from 25.6 preoperatively to 71.4 postoperatively at the time of the final follow-up (≤0.05). Extensively
defective bone was diagnosed preoperatively in 32 patients (≥Paprosky IIB). Plain radiographs showed stable anchorage without
migration in 44 patients. In one case, the stem (implantation time 2.36 years) was replaced due to increasing axial subsidence
(≥5 mm). Good integration of bone graft with subsequent defect regeneration was seen in all patients with bone transplant
(n = 30). Postoperative dislocation occurred in six patients and required closed reduction in four cases. Open reduction was
performed in two patients, whereby the external rotation angle of the prosthetic neck was corrected without dismantling the
distally anchored prosthetic stem components. The mechanical failure rate over the follow-up period of 9 years was one out
of the 48 prospectively investigated prostheses. Rate of survival according to Kaplan-Meier was 97%.
Operative Orthopädie und Traumatologie 04/2012; 19(1):56-77. · 0.46 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Three-dimensional autologous chondrocyte implantation based on collagen gel as matrix scaffold has become a clinically applied treatment for focal defects of articular cartilage. However, the low biomechanical properties of collagen gel makes intraoperative handling difficult and creates the risk of early damages to the vulnerable implant. The aim of the study was to create a stabilized form of collagen gel and to evaluate its biomechanical and biochemical properties.Collagen type-I gel was seeded with human articular chondrocytes. 20 samples were subject to condensation which was achieved mechanically by compression and filtration. Control samples were left uncondensed. From both types of gels 10 samples were used for initial biomechanical evaluation by means of unconfined compression and 10 samples were cultivated under standard conditions in vitro. Following cultivation the samples were evaluated by conventional histology and immunohistochemistry. The proliferation rate was calculated and matrix gene expression was quantified by real-time PCR.The biomechanical tests revealed a higher force carrying capacity of the condensed specimens. Strain rate dependency and relaxation was seen in both types of collagen gel representing viscoelastic material properties. Cells embedded within the condensed collagen gel were able to produce extracellular matrix proteins and showed proliferation.Condensed collagen gel represents a mechanically improved type of biomaterial which is suitable for three-dimensional autologous chondrocyte implantation.
Bio-medical materials and engineering 01/2010; 20(6):317-28. · 1.23 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The purpose of this study was to evaluate the potential value of a cell-free collagen type I gel plug for the treatment of focal cartilage defects. Cellular migration and proliferation was addressed in vitro, and the formation of repair tissue in a nude mouse-based defect model. A cell-free plug made of collagen type I was placed in the center of an incubation plate. Surrounding space was filled with a collagen type I gel (Arthro Kinetics, Esslingen, Germany) seeded with 2 x 10(5) human articular chondrocytes/mL gel. After cultivation for up to 6 weeks in vitro, samples were subject to histological and immunohistochemical staining and gene expression analysis. Subsequently, chondral defects of human osteochondral blocks were treated with the plug, and specimens were cultivated subcutaneously in nude mice for 6 weeks. The repair tissue was evaluated macroscopically, and collagen type II production was investigated immunohistochemically. In vitro, morphology of immigrated cells did not show any differences, as did collagen type II gene expression. After 4 weeks, the plug was homogeneously inhabited. After 6 weeks of cultivation in nude mice, collagen gel plug treatment led to a macroscopically excellent repair tissue. Histological staining revealed a tight bonding, and the collagen gel plug started to be remodeled. We conclude that the novel collagen gel plug device offers an environment favorable for the migration of articular chondrocytes and leads to a good-quality repair tissue in the nude mouse model. The arthroscopic transplantation of a collagen gel plug may be one option in the treatment of focal cartilage defects.
Artificial Organs 01/2010; 34(1):79-83. · 2.00 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Objective Bone-preserving hip resurfacing in young and active patients using a soft-tissue-sparing, modified transgluteal, lateral approach.
Primary hip osteoarthritis in physically active, working patients aged < 65 years (males) and < 60 years (females). Good bone quality.
Male patients > or = 65 years of age, female patients > or = 60 years of age. Necrosis of the femoral head. Varus deformity of the femoral neck with a reduced horizontal femoral offset. Femoral head cysts (> 1 cm in diameter). Infection. Osteoporosis. Rheumatoid arthritis. Tumor. Reduced renal function. Leg length difference (> or = 1 cm). Metal allergy. Previous femoral neck fracture. Previous intertrochanteric femoral osteotomies.
Supine position of the patient. Modified transgluteal, lateral approach to the hip joint. Luxation of the femoral head. First, reaming of the femoral head to improve visualization of the acetabular cup. Central positioning of the guide wire in the femoral neck in a slight valgus position of approximately +5 degrees to the anatomic collodiaphyseal (CCD) angle using the mechanical targeting device. Overdrilling of the central guide wire to the appropriate depth for the implant. Central insertion of the guide rod. Preparation of the femoral head over the guide rod using cylinder cutters one or two sizes larger than the smallest possible femoral component. Cement-free implantation of the acetabular component according to the predetermined definitive size of the femoral component. Final preparation of the femoral head using profile, surface and forming cutter. Following cemented implantation of the femoral component, repositioning of the hip joint and conclusion of the surgical procedure.
Mobilization of the patient using two forearm crutches as of the 1st day after surgery. Removal of the Redon drains after 24 h. Partial weight bearing of 20 kg for 3 weeks under continuation of thrombosis prophylaxis. Limitation of hip flexion to 90 degrees during the first 6 postoperative weeks, and no adduction and forced external rotation allowed in order to avoid luxation. Avoidance of sports involving the loads of jumping and axial impact loading for 12 postoperative months.
Analysis involved the pre- and postoperative functions of 72 patients with a total of 82 prostheses and a mean durability time of 29.2 +/- 11 months based on the Harris Hip Score (HHS), the modified UCLA (University of California, Los Angeles) activity index, and the Merle d'Aubigné Score. Postoperatively, prosthetic angle and femoral offset as well as periprosthetic signs of loosening/lytic areas were assessed by means of radiology and compared with the preoperative CCD angle and femoral offset. Compared to the preoperative evaluation, follow-up yielded a significant increase in the average HHS values (94 +/- 4.6 vs. 40.1 +/- 7 points), the modified UCLA activity index (8.9 +/- 2.6 vs. 4.6 +/- 2.2), and the Merle d'Aubigné Score (17.9 +/- 1.9 vs. 7.3 +/- 2.4; p < or = 0.05). In 98.8%, a solid osteointegration of the cup and femoral components was observed. The average deviation of the physiological CCD angle (136.6 degrees +/- 3.6 degrees ) from the postoperative angle of the prosthesis (142.6 degrees +/- 4.9 degrees ) was 6 degrees +/- 2.8 degrees . The postoperative femoral offset was reduced by an average of 2.3 mm compared to the preoperative offset. During clinical follow-up n = 2 prostheses (2.5%) required revision (one femoral neck fracture; one periarticular ossification [Brooker III]).
Operative Orthopädie und Traumatologie 12/2009; 21(6):586-601. · 0.46 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The most essential improvement of modern hip resurfacing arthroplasty is the metal-on-metal bearing as well as the integration of a procedure for the exact and repeatable positioning of the femoral component through a specific mechanical alignment instrument. Nevertheless, the main reasons for early implant failure are mal-positioning of the femoral component and notching of the femoral neck during femoral head preparation.
In the context of an in vitro study, in each case six DUROM-Hip resurfacing prostheses were implanted in artificial femora with the prosthesis-specific mechanical alignment instrument, as well as under navigation control. The aim of the study was to evaluate the functionality and accuracy of a computer-assisted planning and navigation system on the basis of a navigation module library from Surgitaix AG (Aachen, Germany), as well as a comparison with the prosthesis-specific mechanical alignment instrument.
The main angulation error between planning and navigation of the stem-shaft angle was 0.2+/-1.2 degrees for the navigation system and 6.5+/-4.1 degrees for the mechanical alignment instrument, the main anterior offset error was 1.2+/-1.2 mm vs. -0.83+/-4.1 mm. The mean time for all five planning and navigation steps was 17+/-1.2 min vs. 14+/-0.8 min. The main distance error between planning and navigation was 1.9+/-0.6 mm for the navigation system, and 5.3+/-2.4 mm for the mechanical alignment instrument. Femoral notching was not observed for navigational or conventional positioning.
The computer-assisted fluoroscopic planning and navigation system for hip resurfacing showed, within the scope of this in vitro study, first promising experiences. The system approves a practicable planning with a high accuracy in implementation. Nevertheless, the potential benefit has to be evaluated in further clinical studies, especially from the perspective of a possible integration of this navigation system into the clinical workflow. Further studies should consider a fluoroscopy-assisted range of motion assessment under consideration of an additional cup-module to enhance the postoperative range of motion after hip resurfacing procedures.
Biomedizinische Technik 08/2008; 53(4):204-12. · 0.86 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Even following the introduction of the "third generation" cementing technique, an improvement of the fixation of the acetabular component similar to that of the femoral has not been shown in clinical studies. The goal of the present study was to achieve a better stability with the use of an amphiphilic bonder while preserving the mechanically important subchondral sclerosis.
In a total of 20 sheep, a cemented total hip replacement was implanted. In the treatment group (n = 10), the implantation was carried out following surface conditioning of the acetabular bed with an amphiphilic bonder. All the sheep were followed for 9 months. To assess the biocompatibility, the osseous ingrowth at the cement-bone interface was depicted with the help of an in vivo fluorescent marking of the osteoblasts. Additionally, conventional radiographs were obtained over the course of treatment. Finally, the ovine pelvic regions were split following a standardized technique allowing for histological evaluation of the cement-bone interfaces.
The acetabular components of the treatment group revealed a stable cement-bone compound. In the control group, the implants were easily dislodged from their beds. This finding was consistent with the radiological and histological results, which had revealed increased, progressive lytic radiolucent lines and the interposition of fibrous tissue at the cement-bone interface in the control group compared to the treatment group. The bonder was biocompatible.
Following the application of the bonder, the cemented acetabular components revealed an improved stability without signs of inflammation or neoplasia in a viable acetabular osseous bed. With the help of this technique, the in vivo longevities of cemented acetabular components can be increased in the clinical setting without sacrificing the biomechanical relevant subchondral sclerosis.
Archives of Orthopaedic and Trauma Surgery 08/2008; 128(7):701-7. · 1.37 Impact Factor
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[hide abstract]
ABSTRACT: Symptomatic treatment of osteoarthritis of the knee with leeches is presently undergoing a renaissance. Previous studies have shown methodical weaknesses. In the present study patients were blinded regarding the treatment, and a control group was included to explore possible differences in various subjective clinical scores and intake of pain medication over time between leech therapy and placebo control.
113 patients with advanced osteoarthritis of the knee were included. The patients were randomized to a single treatment group, group I (single leech application, n = 38), a double treatment group, group II (double application, n = 35), and a control group (n = 40). The second treatment in group II took place after an interval of 4 weeks. The treatment in the control group was simulated with the help of an "artificial leech". Results were documented with the KOOS and WOMAC scores and also a visual analog scale (VAS) for pain. Changes in the use of pain medication were monitored over 26 weeks.
An improvement in KOOS and WOMAC scores, and also in VAS, was found in all 3 groups following treatment. These improvements were statistically significant for treatment groups I and II during the complete follow-up period. The reduction in individual requirements for pain medication was also statistically significant. The greatest improvement was seen in the group treated twice with the leeches, with a long-term reduction of joint stiffness and improved function in the activities of daily living.
Leech therapy can reduce symptoms caused by osteoarthritis. Repeated use of the leeches appears to improve the long-term results. We have not determined whether the positive outcome of the leech therapy is caused by active substances released during the leeching, the placebo effect, or the high expectations placed on this unusual treatment form.
Acta Orthopaedica 05/2008; 79(2):235-43. · 2.17 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Restoration of a painless hip joint capable of bearing weight by uncemented implantation of a rotationally stable, modular revision stem anchored in the diaphysis.
Prosthetic stem loosening with osteolytic bone defects (defect classification types I-III according to Paprosky). Material failure with broken prosthesis. Sub- and/or periprosthetic femoral fractures. Tumors.
Extensive osteolysis preventing diaphyseal anchorage of the prosthesis.
Transgluteal approach to the hip joint. Removal of the loose prosthetic stem and, if cemented, the bone cement as well. Excision of intramedullary granulation tissue. Reaming of the medullary cavity with flexible reaming shafts and form-fit, uncemented implantation of the star-shaped modular revision stem with diaphyseal press fit. If there is extensive loss of metaphyseal bone stock, augmentation with autogenous/allogenic bone should be performed.
Mobilization on two underarm crutches from the 1st postoperative day. Removal of the Redon drains after 48 h. Partial loading with 20 kg for 6 weeks postoperatively. If plain radiographs show unchanged seating of the prosthesis after 6 weeks, loading can be increased by 10 kg per week until full weight bearing is achieved; thrombosis prophylaxis is continued throughout. Radiologic checkups after 3, 6, and 12 months. After that, the patient should be checked annually.
45 patients (n = 48 prostheses) with an average age of 67.2 years (min.-max. 42.4-87.4 years) were investigated. The average implantation time of the Modular Revision Prosthesis MRP-TITAN revision stem was 4.7 years (min.-max. 1.0-9.0 years). The Harris Hip Score for Paprosky bone defect types I-III had increased from 25.6 preoperatively to 71.4 postoperatively at the time of the final follow-up (< or = 0.05). Extensively defective bone was diagnosed preoperatively in 32 patients (> or = Paprosky IIB). Plain radiographs showed stable anchorage without migration in 44 patients. In one case, the stem (implantation time 2.36 years) was replaced due to increasing axial subsidence (> or = 5 mm). Good integration of bone graft with subsequent defect regeneration was seen in all patients with bone transplant (n = 30). Postoperative dislocation occurred in six patients and required closed reduction in four cases. Open reduction was performed in two patients, whereby the external rotation angle of the prosthetic neck was corrected without dismantling the distally anchored prosthetic stem components. The mechanical failure rate over the follow-up period of 9 years was one out of the 48 prospectively investigated prostheses. Rate of survival according to Kaplan-Meier was 97%.
Operative Orthopädie und Traumatologie 03/2007; 19(1):56-77. · 0.46 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Cemented femoral stems have shown decreased longevity compared to cementless implants in hip revision arthroplasty. The aim of this study was to evaluate the effect of an amphiphilic bonder on bone cement stability in a biomechanical femur expulsion test. A simplified hip simulator test setup with idealised femur stem specimens was carried out. The stems were implanted into bovine femurs (group 1: no bonder, n=10; group 2: bonder including glutaraldehyde, n=10; group 3: bonder without glutaraldehyde, n=10). A dynamic loading (maximum load: 800 N; minimum load: 100 N; frequency: 3 Hz; 105 cycles) was performed. Subsequently, the stem specimens were expulsed axially out of their implant beds and maximum load at failure was recorded. The static controls showed a mean maximum load to failure of 4123 N in group 1, 8357.5 N in group 2 and 5830.8 N in group 3. After dynamic loading, the specimens of group 2 reached the highest load to failure (8191.5 N), followed by group 3 (5649.5 N) and group 1 (3462 N), respectively. In group 2, we observed nine periprosthetic fractures at a load of 8400 N without signs of interface loosening. Application of an amphiphilic bonder led to a significant improvement of bonding stability, especially when glutaraldehyde was added to the bonder. This technique might offer an increased longevity of cemented femur revision stems in total hip replacement.
Biomedizinische Technik 02/2007; 52(6):391-7. · 0.86 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Wear of ultra-high-molecular-weight polyethylene (UHM-WPE) inlays is associated with aseptic loosening in total knee replacement (TKR). The aim of this study was to investigate the in vitro performance of a TKR system that combines several measures to decrease UHMWPE wear. Tests were carried out on a BPK-S Integration system (R&D, P. Brehm Chirurgie-Mechanik, Weisendorf, Germany) according to ISO 14,243-1 in a knee joint simulator. Calf serum with a high protein concentration of 30 g/l was chosen as the test lubricant. PE wear was measured gravimetrically. Particle analysis was performed by scanning electron microscopy, with measurement of particle size and shape. Low mean wear rates of 1.20 mg per million cycles were found for the fixed bearing type and 2.47 mg per million cycles for the rotating-platform bearing design. Anteroposterior deflection was low. The contact areas for both types of bearings were large and showed a constant pattern throughout the test. Backside wear was obvious on rotating platforms. Particle analysis revealed equally sized and round-shaped particles in both types of bearings (fixed, 0.35 microm; mobile, 0.32 microm). In conclusion, the combination of design features and surface modifications of the BPK-S integration TKR system leads to low gravimetric UHMWPE wear.
Biomedizinische Technik 01/2007; 52(4):295-300. · 0.86 Impact Factor
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ABSTRACT: Metallic materials in orthopaedic implants must bear mechanical loads with resultant surface damage. In addition to mechanical load, the surface damage on the implants occurs due to electrochemical corrosion from the physiological environment in-vivo. This research investigates in vitro experimental test bodies (surface area: 4.71cm2) of four different ISO (International Organization for Standardization) standardised, frequently used, artificial implant alloys (TiAl6V4, Ti, CoCr29Mo, FeCrNiMoMnNbN). The test materials were immersed in inert polystyrene test tubes filled with 1ml of serum (pH 7.4) by avoidance of any friction and mechanical load. Here, they were subject to electrochemical corrosion independently of mechanical influences when in contact with body liquids. It was found that up to 80% of the entire dissolution of each ion occurred within the first 24h of immersion. Additionally, the dissolution of the metal ions depended on the proportional mix of the individual elements in respective alloys. Therefore, the highest percent of ion concentration was found for Co (CoCr29Mo) followed by Fe (FeCrNiMoMnNbN) and Mo (FeCrNiMoMnNbN). The lowest percent of ion concentrations were evident for Ti (Ti), Cr (CoCr29Mo) and Cr (FeCrNiMoMnNbN).Les composants mtalliques des implants orthopdiques doivent supporter des contraintes mcaniques entranant des dtriorations de surface. En plus de la charge mcanique les dtriorations de surface des implants se produisent en raison de la corrosion lectrochimique de lenvironnement physiologique in vivo. Cette recherche tudie les matriaux exprimentaux tests in vitro (superficie : 4.71 cm2) de quatre alliages (TiAl6V4, Ti, CoCr29Mo, FeCrNiMoMnNbN) frquemment utiliss et ISO (International Organization for Standardization) normaliss. Les matriaux dessai ont t immergs dans les tubes essais en polystyrne inerte remplis de 1ml du srum (pH 7.4) afin dviter tout frottement et charge mcanique. Dans ces tubes essais, ils sont soumis la corrosion lectrochimique indpendamment des influences mcaniques quand ils sont en contact avec les liquides organiques. On a constat que prs de 80 pour cent de la dissolution entire de chaque ion sest produite dans les 24 premires heures de limmersion. En plus, la dissolution des ions mtalliques dpend de la proportion des diffrents lments de chaque alliage. Par consquent les plus grands pourcentages de concentration ionique ont t trouvs pour le Cobalt (CoCr29Mo), puis du Fer (FeCrNiMoMnNbN) et du Molybdne (FeCrNiMoMnNbN). Les plus bas pourcentages de concentration ionique taient vidents pour le Titane (Ti), le Chrome dans lalliage (CoCr29Mo) et dans lalliage (FeCrNiMoMnNbN).
European Journal of Orthopaedic Surgery & Traumatology 04/2005; 15(2):83-89. · 0.10 Impact Factor
