Erwin Steinhauser

Impaired wound-healing, local eczema, and chronic inflammation following titanium osteosynthesis in a nickel and cobalt-allergic patient: a case report and review of the literature.

Patients known to develop allergic reactions to nickel (Ni), cobalt (Co), or chromium (Cr) often develop eczema in association with items of daily use such as jewelry, earrings, or watchbands. The overall sensitization rates to these metals may range between 1.1% (chromium) and 13% (nickel) in the general population, with further differences based on age and sex1. Chromium-cobalt alloys and stainless steel are widely used as orthopaedic implants and may release nickel, chromium, or cobalt into the surrounding tissues as a consequence of either wear or corrosion2. Some patients with a metal allergy may develop dermatitis in association with orthopaedic implants, and the prevalence of dermal sensitivity in patients with a joint replacement, particularly a failed implant, is higher than that in the general population3. Metal sensitivity rates to nickel, cobalt, or chromium may be as high as 43% in orthopaedic patients with well-functioning implants and as high as 71% in patients with poorly functioning implants3. In contrast, because of their excellent biocompatibility, titanium (Ti)-based materials are not considered to provoke allergic reactions. Our patient developed eczema and impaired wound-healing following the fixation of an ankle fracture with titanium-based implants. Histological analysis of the tissue around the implant demonstrated inflammation primarily with lymphocytes, and a contact allergy to nickel and cobalt was found in the absence of titanium hyperreactivity, raising the question of a prior unknown nickel exposure as the source of the complications. The patient was informed that data concerning this case would be submitted for publication, and she consented. A fifty-nine-year-old woman with a trimalleolar ankle fracture with rupture of the syndesmosis (Fig. 1) underwent open reduction and internal fixation of the fractures with a titanium plate (catalogue number 441.370; Synthes, STRATEC Medical, Oberdorf, Switzerland) and screws (catalogue numbers 404.812, …

Pitfalls in the use of acetabular reinforcement rings in total hip revision

Introduction: For the reconstruction of acetabular bone defects different types of acetabular reinforcement rings are being used. In clinical practice, these implants showed to some extent good long-term results. In the present work pitfalls and complications after the implantation of acetabular reinforcement rings as well as possible solutions are being discussed. Material and methods: In the first case recurrent dislocation was caused by the malposition of the acetabular component with an impingement of the protruding bone cement and the anterior edge of the acetabular ring as well as muscle insufficiency as a result of the shortening of the leg length. The second case revealed an impingement of the iliopsoas tendon due to a protruding acetabular reinforcement ring. During revision, bone cement was used to smoothen the protruding anterior edge of the acetabular reconstruction ring in order to obtain a relieved sliding of the tendon. Furthermore, we report on the case of a delayed neuropathy of the sciatic nerve after reconstruction of the acetabulum with an acetabular reinforcement ring. Results: Intraoperatively an impingement of the sciatic nerve at the protruding dorsal edge of the acetabular reinforcement ring and the surrounding scar tissue was found. In a further case an aseptic loosening of an acetabular reinforcement ring caused the formation of an excessive granuloma with a large intrapelvic portion. The granuloma led to persisting senso-motoric deficits of the femoral nerve. In summary, based on these clinical cases possible pitfalls, associated with the use of acetabular reinforcement rings, are shown. The mal-positioning and the intra-operative re-shaping of the implant by the surgeon are pointed out as the substantial factors for the occurrence of an impingement phenomenon and total hip instability. Furthermore, in case of an adequate orientation of the cemented polyethylene insert an improper position of the acetabular ring which results in protruding edges has to be considered as a cause of a prosthetic impingement. Conclusion: The cases presented emphasize the necessity of prevention of such pitfalls intra-operatively as well as accurate analysis of implant failures. Furthermore, they suggest explicit preoperative planning before deciding on the strategy of revision surgery of acetabular reinforcement rings.

Methode zur Evaluierung von Einflußfaktoren auf die Luxationsstabilität von künstlichen Hüftgelenken / Method for the Evaluation of Factors Influencing the Dislocation Stability of Total Hip Endoprotheses

Abstract Nach künstlichem Hüftgelenkersatz ist die Luxation eine schwerwiegende Komplikation. Verschiedene Einflußfaktoren auf die Luxationssicherheit wurden klinisch ermittelt. Unser Ziel war die Entwicklung einer Methode, mit der die Parameter Implantat-Design, Position sowie Belastungssituation hinsichtlich der Luxationsstabilität experimentell untersucht und bewertet werden können. Auf Basis des neu entwickelten Prüfmodells können die Bewegungsumfänge bis zum Impingement und zur Luxation bei verschiedenen Implantatpositionen ermittelt werden. Zudem werden die auftretenden Drehmomente bei Subluxation, d.h. beim Heraushebeln des Kopfes, bestimmt. Beispielhaft wurden einzelne Hüft-Implantate in bestimmten luxationsassoziierten Bewegungskombinationen wie (Innen-) Rotationsbewegungen mit 90° Flexion und 0° Adduktion sowie (Außen-)Rotationsbewegungen mit 10° Extension und 15° Adduktion untersucht. Unabhängig von Implantat-Design und -Position können dabei folgende Bewegungsphasen unterschieden werden: ungestörte Bewegung, Impingement, Subluxation und letztlich die komplette Luxation des Kopfes. Anhand der Bewegungsumfänge der einzelnen Phasen, auftretender Drehmomente und Luxationsrichtung können verschiedene Implantat-Systeme vergleichend analysiert werden. Exemplarisch wird in dieser Arbeit der Einfluß des Kopfdurchmessers auf die Luxationsstabilität des künstlichen Hüftgelenkes dargelegt. Mit Hilfe des vorgestellten Prüfmodells kann für verschiedene Implantatkombinationen ein Datensatz mit der günstigsten bzw. luxationsstabilsten Implantatposition erstellt werden. Zudem können angesichts der beschriebenen Phasen wesentliche Erkenntnisse für das Implantat-Design gewonnen und somit Rückschlüsse für Neuentwicklungen bzw. Modifikationen an bestehenden Implantatkomponenten gezogen werden. Dislocation of the artificial joint is a serious complication of total hip replacement. Various factors with an influence on dislocation stability were determined clinically. Our goal was to develop a method for evaluating experimentally the parameters implant design, position and the load situation for their influence on joint stability. With the newly developed testing device the range of motion to impingement and to dislocation can be determined at different implant positions. In addition, the rotational moments on subluxation, i.e. the “levering out” of the femoral head, can be determined. By way of example several hip implants were examined during movements associated with dislocation, e.g. (internal-)rotation in 90° flexion and 0° adduction as well as with (external-)rotation in combination with 10° extension and 15° adduction. Irrespective of implant design and position, the following movement phases can be differentiated: undisturbed motion, impingement, subluxation and, finally, complete dislocation of the head. On the basis of the range of motion of the specific phases, the moments occurring and the direction of dislocation, different implant systems can be compared. In this study the influence of the head diameter on the dislocation stability of the hip endoprosthesis is shown. With the aid of the model presented herein, a data set showing the most favourable and/or most dislocation stable implant position can be acquired for different combinations of the implant components. Additionally, useful information for implant design can be deduced and applied to new developments and/or modifications of existing implant components.

Alloplastic reconstruction of the extensor mechanism after resection of tibial sarcoma.

Reconstruction of the extensor mechanism is essential for good extremity function after endoprosthetic knee replacement following tumor resection. Only a few biological methods have been able to reliably restore a functional extensor mechanism, but they are often associated with significant complication rates. Reattachment of the patellar tendon to the prosthesis using an alloplastic patellar ligament (Trevira cord) can be an appropriate alternative. In vivo and in vitro studies have already shown that complete fibrous ingrowth in polyethylene chords can be seen after a period of six months. However, until now, no biomechanical study has shown the efficacy of an alloplastic cord and its fixation device in providing sufficient stability and endurance in daily life-activity until newly formed scar tissue can take over this function. In a special test bench developed for this study, different loading regimes were applied to simulate loads during everyday life. Failure loads and failure modes were evaluated. The properties of the cord were compared before and after physiological conditioning. It was shown that rubbing was the mode of failure under dynamic loading. Tensile forces up to 2558 N did not result in material failure. Thus, using an artificial cord together with this fixation device, temporary sufficient stable fixation can be expected.

Biomechanical properties of articular cartilage after high hydrostatic pressure treatment

Zusammenfassung Ziel: Zu den aktuellen Rekonstruktionsverfahren großer tumorbefallener Knochendefekte gehören die intraoperative extrakorporale Bestrahlung oder Autoklavierung mit anschließender Reimplantation. Dies führt jedoch zum Teil zu einer erheblichen Veränderung der Transplantatqualität. Mitl der hydrostatischen Hochdrucktechnik (HHD) kommt eine neue Alternative zur experimentellen Anwendung. Maligne Tumorzellen sollen unter Erhalt der biomechanischen Eigenschaften abgetötet werden. Ziel der vorliegenden Arbeit ist es, die biomechanischen und immunhistologischen Auswirkungen einer HHD-Behandlung auf Knorpelgewebe zu untersuchen. Material und Methode: Osteochondrale Segmente aus bovinen Femurkondylen wurden mit HHD bei 300 und 600 MPa behandelt (je n=20). Biomechanische und immunhistologische Eigenschaften von behandelten und unbehandelten Segmenten wurden durch einen speziell entwickelten repetitiven Kugeleindrückversuch sowie durch die immunhistochemische Anfärbung von Aggrecan und Link Protein evaluiert. Kontralaterale Segmente dienten jeweils als unbehandelte Kontrolle. Ergebnisse: Es zeigte sich selbst nach einer Behandlung der osteochondralen Segmente bei 600 MPa keine signifikante Änderung der Steifigkeit und des Relaxationsverhaltens. Immunhistochemisch ergab sich in allen Proben eine erhaltene Anfärbbarkeit der Kollagene, Proteoglykane und kein Unterschied im Verteilungsmuster zwischen behandelten und unbehandelten Proben. Schlussfolgerung: Bei der Behandlung von Knorpelgewebe mit HHD werden normale und Tumorzellen unter Erhalt der biomechanischen und immunhistologischen Eigenschaften zerstört. Somit besteht die Möglichkeit, nach Resektion eines tumorbefallenen Knorpel-Kno-chenareals durch HHD ein tumorfreies autologes Segment zwecks Reimplantation zu erstellen.

New method for determining in vitro structure stiffness of ceramic acetabular liners under different impact conditions

Increasing both patient mobility and prosthesis life span requires improvements in the range of motion and wear behavior of the liner. With the use of new composite alumina-zirconia ceramic materials, the same stability of the liner can be achieved at lower wall thickness than it is possible with alumina-only materials. The aim of this study was developing a method for determining the in vitro structure stiffness of ceramic acetabular liners against impact stresses. The first trials were performed with a common alumina acetabular liner type (Ceramtec; Biolox forte; diameter 28 mm; thickness 7 mm) and a new type of alumina-zirconia (Ceramtec Biolox delta; same dimensions) liner. The clinically established alumina liner was reproducibly damaged using worst case Separation/subluxation equivalent to one-fourth or half of the head diameter, and an impact load of 15 J. The liners containing the new alumina-zirconia material were not damaged in any of the trials up to an impact load of 20 J and half head diameter offset.

Tissue Engineering von Knochen- und Knorpelgewebe: Die Bedeutung von Sauerstoff und Hypoxie

The use of porous scaffolds in Tissue Engineering results in the possibility to create 3-D constructs. A limiting factor is the relatively low oxygen and nutrient supply in the center of the scaffolds. This leads to only small constructs of about 500 μm thickness. Engineered cartilage reaches diameters about 1 mm. Elevated pO2, for example induced by hyperbaric oxygen (HBO), could improve this situation. Nevertheless, hyperand hypoxia play also an important role in cells, regulating proliferation, differentiation and macromolecular synthesis. The present work gives an overview about the role of oxygen, hypoxia and HBO in osteoblasts and chondrocytes and should allow conclusions for an improved Engineering of bone and cartilage tissues. Literatur [1] Aitasalo K., Niinikoski J., Grenman R., Virolainen E.: A modified protocol for early treatment of osteomyelitis and osteoradionecrosis of the mandible. Head Neck 20, 1998, 411-17 [2] Akeno N., Czyzyk-Krzeska M. F., Gross T. S., Clemens T. L.: Hypoxia induces vascular endothelial growth factor gene transcription in human osteoblast-like cells through the hypoxia-inducible factor-2alpha. Endocrinology 142, 2001, 959-62 [3] Brighton C. T., Schaffer J. L., Shapiro D. B., Tang J. J., Clark C. C.: Proliferation and macromolecular synthesis by rat calvarial bone cells grown in various oxygen tensions. J Orthop Res 9, 1991, 847-54 [4] Davis T. R. C, Holloway I. T., Pooley J.: Effect of exposure air elevated oxygen levels on bone blood flow in the rabbit. Undersea Biomed Res 17,1990, 201-11 [5] Deahl S. T.: 2 d, Oberley LW, Oberley TD, Elwell JH. Immunohistochemical identification of superoxide dismutases, catalase, and glutathione-S-transferases in rat femora. J Bone Miner Res 7, 1992, 187-98 [6] Domm C., Schunke M., Christesen K., Kurz B.: Redifferentiation of dedifferentiated bovine articular chondrocytes in alginate culture under low oxygen tension. Osteoarthritis Cartilage 10, 2002, 13-22 [7] Freed L. E.: Vunjak-Novakovic G. Culture of organized cell communities. Adv Drug Deliver Rev 33, 1998, 15-30 [8] Frerich B., Kurtz-Hoffmann J., Lindemann N., Muller S.: Tissue engineering of vascularized bone and soft tissue transplants. Mund Kiefer Gesichtschir Suppl 2, 2000, 490-95 [9] Grimshaw M. J., Mason R. M.: Bovine articular chondrocyte function in vitro depends upon oxygen tension. Osteoarthritis Cartilage 8, 2000, 386-92 [10] Hansen U., Schunke M., Domm C., Ioannidis N., Hassenpflug J., Gehrke T., Kurz B.: Combination of reduced Florian-Dominique Naal

The influence of head and neck geometry on stability of total hip replacement

BACKGROUND Dislocation after replacement may be caused by poor implant design or positioning, or by the surgical approach taken. We evaluated the influence of head and neck design on range of motion and stability (with respect to risk of dislocation) in total hip endoprostheses. MATERIAL AND METHODS Using a test device, we determined the stability afforded by different head sizes and neck geometries for various implant positions. RESULTS Increasing head diameter led to an enhancement of range of motion as well as resistance against subluxation, and thus to improved stability in any movement combination and implant orientation. Smaller femoral heads were associated with increased risk of dislocation, especially in a poor implant position such as retroversion, and steep positioning of the cup. Skirted metal or mushroom-shaped ceramic heads had a reduced range of motion until impingement of approx. 20 degrees, as compared to spherical standard heads. Furthermore, after identical joint loading, skirted heads dislocated more readily than standard heads with corresponding diameters. INTERPRETATION To obtain sufficient joint mobility and stability, neck geometry and implant position should be considered when choosing the femoral head size.

Biomechanical investigation of uniplanar and biplanar cuts in openingwedge high tibial osteotomy

This study was aimed to determine the biomechanical properties of uniplanar tranversial (UPO) and biplanar, three-dimensional (BPO) osteotomy in medial opening wedge high tibial osteotomy (HTO) in a comparable Sawbone model. Third generation tibial Sawbones were osteotomized in a standardized manner and fixed with an angle-stable, spacer containing plate. Axial stiffness after one and twenty loading cycles (range 50 to 1000 N) was registered as well as displacement within the osteotomy gap and load at failure. After one loading cycle no differences between BPO (n=5) and UPO (n=5) specimens were evaluated. The undergoing of 20 loading cycles caused a significant loss of stiffness. After the cycles BPO specimen had a stiffness of 1755.9 ± 129.2 N/mm. The stiffness in UPO specimen was 1018.5 ± 15.5 N/mm. The difference between the groups was significant. The mean maximum load at failure in UPO specimens was 2633.1 ± 229.4 N. Specimens after BPO had a significant higher maximum load at failure of 4554.8 ± 342.8 N. In BPO specimens the failure always was caused by an infraction in the lateral cortex, whereas in UPO the failure was caused in two-times by an additional dorsal dislocation of the tibial head. This study was undertaken to evaluate the biomechanical properties of a UPO and BPO in medial wedge osteotomy. The results offer a significant advantage for the BPO regarding to axial stiffness under cyclic loading as well as resistance against load to failure. References [1] Bergenudd H,Sahlstrom A,Sanzen L. Total knee arthroplasty after failed proximal tibial valgus osteotomy. J Arthroplasty 1997; 12: 635-638. [2] Coventry MB. Osteotomy of the upper portion of the tibia for degenerative arthritis of the knee. J Bone Joint Surg Am 1965; 47: 984-990. [3] Insall JN,Joseph DM,Msika C. High tibial osteotomy for varus gonarthrosis. A long-term follow-up study. J Bone Joint Surg Am 1984; 66: 1040-1048. [4] Klinger HM,Lorenz F,Harer T. Open wedge tibial osteotomy by hemicallotasis for medial compartment osteoarthritis. Arch Orthop Trauma Surg 2001; 121: 245-247. [5] Koshino T,Murase T,Takagi T,Saito T. New bone formation around porous hydroxyapatite wedge implanted in opening wedge high tibial osteotomy in patients with osteoarthritis. ORIGINAL ARBEITEN Gunter Spahn: Biomechanical investigation of uniplanar cuts in opening-wedge high tibial osteotomy Width the dorsal osteotomy gap [mm] under a load of 1000 N After 1 cycle After 20 cycles

In-vivo-Studie zur knöchernen Integration von RGD-Peptid-beschichteten und unbeschichteten metallischen Implantaten*

Kurzfassung Wunsch bei zementfreier Fixation von Endoprothesen ist deren möglichst frühzeitige und dauerhafte knöcherne Integration. In Zellversuchen konnte gezeigt werden, dass die Beschichtung von Implantatwerkstoffen mit RGD-Peptiden eine gesteigerte Adhäsion von Knochenzellen (Osteoblasten) induzieren kann. Ziel dieser Studie war es zu ermitteln, ob die RGD-Peptid-Beschichtung die Integration von metallischen Implantaten auch im Großtier verbessert. Für die Frühphase nach der Implantation (4 Wochen) konnten hierbei eine verbesserte knöcherne Integration und eine Steigerung der mechanischen Festigkeit von 68% an der Grenzfläche zwischen beschichtetem Implantat und Knochen ermittelt werden. Nach 12 Wochen waren die Unterschiede zu den unbeschichteten Kontroll-Implantaten weniger markant ausgeprägt.