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In 2016, the AG 11 (work group for implant-material-intolerance) of the German society for Orthopaedics and Orthopaedic Surgery (DGOOC) created a histopathologic implant register (HIR). The goal was to conduct a retrospective data analysis based on the revised SLIM-consensus-classification, which defines eight different failure mechanisms.The analysis of 4000 cases of endoprosthetic joint replacements addressed the following questions: 1. What is the frequency distribution of different SLIM-types? 2. How does durability of endoprosthetic joint replacements differ among SLIM-types? 3. What kind of periprosthetic malignant neoplasia can be detected and how often?SLIM-type I was diagnosed in 1577 cases (n = 1577, 39.4%), SLIM-type II in 577 cases (n = 577; 14.4%), SLIM-type III in 146 cases (n = 146; 3,7%), SLIM-type IV in 1151 cases (n = 1151; 28.8%), SLIM-type V in 361 cases (n = 361; 9.0%), SLIM-type VI in 143 cases (n = 143; 3.6%), SLIM-type VII in 42 cases (n = 42; 1.0%), and SLIM-type VIII in 3 cases (n = 3; 0.075%). There was statistical significance in implant durability between the different SLIM types. Among the different reasons for endoprosthetic joint replacement failure, non-infectious causes have the biggest share at 81%, with SLIM-type I (39.5%), and SLIM-type IV (29.4%) being the predominant SLIM types. Three cases of periprosthetic malignant neoplasia (SLIM-type VIII) were detected: one case of small B lymphocytic lymphoma/BCLL (C85.9; ICD-O: 9670/3), one case of diffuse large B‑cell lymphoma/DLBCL (C83.3; ICD‑O 9680/3), and one case of anaplastic large cell lymphoma (C84.7; ICD-O: 9714/3), with the latter ones being the causes for joint replacement , which indicates that malignant neoplasia is a very rare cause of endoprosthetic joint replacement (n = 2; 0.05%).These data are complete new, especially as concerns arthrofibrosis (SLIM-type V), adverse inflammatory reactions (SLIM-type VI), and the very rare cases of periprosthetic malignant neoplasia, SLIM-type VIII, as a reason for revision. Since neither the annual review (2017) of the EPRD, nor the national evaluation report (2017) of the IQTIG provide sufficient data, this indicates the relevance of the HIR of the AG 11 of the DGOOC.

Anhand klinischer Beispiele wird das Spektrum der adversen Reaktionen gegenuber Metallimplantaten und hier insbesondere bei Knieprothesen dargestellt. In der Praxis haben wir es haufig mit Frauen nach Kniegelenkersatz und mit Schmerzen, Schwellungen und lokalen oder generalisierten Hauterscheinungen und Osteolysen meist innerhalb der ersten 4 Jahre nach Operation zu tun. Bei allen klinisch auffalligen Patienten sollte eine allergiespezifische Anamnese erhoben und bei entsprechendem Verdacht ein Epikutantest durchgefuhrt werden; evtl. kann die Metallkonzentration von Chrom und Kobalt im Blut gemessen werden. Vor einer Wechseloperation am Knie empfehlen wir dringlich eine arthroskopische Inspektion und groszugige Probengewinnung fur die histopathologische und mikrobiologische Bewertung gemas der histopathologischen Konsensusklassifikation. Erst danach kann eine gezielte Therapie durchgefuhrt werden. Ungezielte weitere Operationen konnten so vermieden werden.

Die Identifikation von partikularen Prothesenmaterialbestandteilen in der histopathologischen Synovialitis- bzw. Periprothetischen-Membran-/Synovial-like-interface-membrane(SLIM)-Diagnostik besitzt zur Abklarung des Gelenkendoprothesenversagens einen wichtigen Stellenwert. Im histopathologischen Partikelalgorithmus werden Polyethylen(PE)-Partikel mit Maximallangen von bis zu 100 µm als Makropartikel bezeichnet, es fehlt jedoch eine systematische Untersuchung und Charakterisierung. Bei den Praparaten der SLIM des Knies (n = 24) wurde ein Minimalwert von 210 µm und ein Maximalwert von 2100 µm gemessen; die arithmetischen Mittelwerte der Langen variierten zwischen 235 µm und 1416 µm. Bei den Huft-SLIM-Praparaten (n = 11) lag eine Minimalwert von 290 µm und einen Maximalwert von 1806 µm vor; die Mittelwerte der Langen variierten zwischen 353 und 1726 µm. Aufgrund dieser auffalligen Grose und zur Abgrenzung von PE-Makropartikeln wird die Bezeichnung supramakropartikulare PE-Partikel vorgeschlagen. Diese neue Bezeichnung wurdigt die Tatsache, dass diese PE-Partikel bei sog. Lupenvergroserung (z. B. 12,5-fach) und auch ohne optische Hilfsmittel sichtbar sind. Die Partikel wurden auch indirekt als vollstandig herausgeloste und optisch leere, der PE-Partikelform entsprechende spaltenformige Hohlraume (PE-Vakuolen) nachgewiesen. Die Prothesenstandzeiten zeigten eine hohe Variabilitat von 12 bis 300 Monaten; es lagen in allen Fallen Lockerungen der Prothesen, Dezentrierung der PE-Komponenten bzw. Schadigungen des PE-Inlays vor. Die Ursache und die Entstehung der supramakropartikularen PE-Partikel (groser als 100 µm) sind noch unklar. Eine mechanische Dysbelastung scheint wahrscheinlich und muss diskutiert werden. Bei kurzen Prothesenstandzeiten konnte der Nachweis von supramakropartikularen PE-Partikeln in der SLIM Ausdruck eines schon fruh einsetzenden mechanischen Problems sein. Im erweiterten histopathologischen Partikelalgorithmus wurden supramakropartikulare PE-Partikel in der Kategorie Makropartikel berucksichtigt und sollten in der histopathologischen Diagnostik des Gelenkprothesenversagens berucksichtigt werden.

Background Cross-talk between synovial fibroblasts (SF) and immune cells is suggested to play a crucial role in inflammation and chronification of rheumatoid arthritis (RA). The contribution of B cells in this process is poorly defined. Methods Here, primary B cells from healthy donors were polyclonally activated and cocultured with SF of non-synovitic origin from patients with osteoarthritis. Results In B–SF cocultures the concentrations of interleukin 6 (IL-6) and IL-8 increased manifold compared with single cultures even under physical separation and remained stable for several days after B-cell removal. Intracellular staining confirmed SF as key producers of IL-6 and IL-8, and B cells as main producers of tumour necrosis factor alpha (TNFα) and IL-1s. Blocking experiments with a combination of anti-TNFα-antibodies and rIL-1RA significantly reduced SF cytokine production by up to 90%, suggesting that B-cell-derived TNFα and IL-1s were crucial mediators of SF activation. Interestingly, B-cell cytokine production, CD25 expression and proliferation decreased in cocultures by at least 50%, demonstrating a negative regulatory loop towards the activated B cells. Inhibition of activin receptor-like kinase 5, a crucial component of the tumour growth factor s (TGFs) signalling pathway, partly restored B-cell proliferation, suggesting a contribution of SF-derived TGFs in B-cell suppression. Besides cytokines, B-cell-activated SF also upregulated secretion of matrix metalloproteases such as MMP-3, thereby acquiring potential tissue destructive properties. This was confirmed by their invasion into human cartilage in the severe combined immunodeficiency mouse fibroblast invasion model in vivo. Conclusions Interaction with activated B cells leads to conversion of non-arthritic SF into SF with a proinflammatory and aggressive RA-like phenotype, thereby suggesting a new, so far unrecognised role for B cells in RA pathogenesis.

Background and purpose — The most frequent cause of arthroplasty failure is aseptic loosening—often induced by particles. Abrasion material triggers inflammatory reactions with lymphocytic infiltration and the formation of synovial-like interface membranes (SLIM) in the bone–implant interface. We analyzed CD3 quantities in SLIM depending on articulating materials and possible influences of proven material allergies on CD3 quantities. Patients and methods — 222 SLIM probes were obtained from revision surgeries of loosened hip and knee arthroplasties. SLIM cases were categorized according to the SLIM-consensus classification and to the particle algorithm. The CD3 quantities were analyzed immunohistochemically, quantified, and correlated to the particle types. Results — Metal–metal pairings showed the highest CD3 quantities (mean 1,367 counted cells). CD3 quantities of metal–polyethylene (mean 243), ceramic–polyethylene (mean 182), and ceramic–ceramic pairings (mean 124) were significantly smaller. Patients with contact allergy to implant materials had high but not statistically significantly higher CD3 quantities than patients without allergies. For objective assessment of the CD3 response as result of a pronounced inflammatory reaction with high lymphocytosis (adverse reaction), a defined CD3 quantity per high power field was established, the “CD3 focus score” (447 cells/0.3 mm2, sensitivity 0.92; specificity 0.90; positive predictive value 0.71; negative predictive value 0.98). Interpretation — The high CD3 quantities for metal–metal pairings may be interpreted as substrate for previously described adverse reactions that cause severe peri-implant tissue destruction and SLIM formation. It remains unclear whether the low CD3 quantities with only slight differences in the various non-metal–metal pairings and documented contact allergies to implant materials have a direct pathogenetic relevance.

In total hip arthroplasty fixation of revision stems can be demanding due to femoral bone loss. Strut grafts are often used for bone augmentation and stabilization of the newly inserted prosthesis. The aim of this study was to assess the effect of strut grafts on primary stability under various stem fixation conditions.Two different revision stems (cylindrical and conical shape) were implanted into synthetic femora. Following a semicircular transfemoral osteotomy, three deficient femoral bearings were simulated (bony lid reattached with cable wires; weakened lid reattached with cable wires; strut grafts placed to the weakened lid with cable wires). Relative micro-movements were measured between prostheses and bones due to an axial moment applied to the stems.Relative movements correlated to the stem shape. The cylindrical stem showed higher movements increasing significantly with a weakened bony lid and portrayed a slight decrease of movements with strut graft application. No unequivocal influence of the weakened lid could be detected for the conical implant. Strut graft application did not show an additional stabilizing effect.The primary stability of the cylindrical fixation concept decreases with impaired fixation conditions of the femur. A clear restabilizing effect with strut grafts could not be proven. A decrease of primary stability due to the impaired bone could not be observed for the conical stem shape. Additionally, strut grafts do not enhance fixation for this stem shape. We conclude that surgeons should not rely on a stabilizing effect of strut grafts in revision hip surgery.

When it comes to endoprosthesis pathologies, for example, implant-allergic/toxic problems, as a cause of implant failure, particle identification has an important role to play in the histopathological diagnostics of the neosynovial/periprosthetic membrane (synovial-like interface membrane, SLIM). The variability of materials in endoprosthetics and differences in particle pathogenesis explain the particle heterogeneity that hampers the diagnostic identification of particles. For this reason, a histopathological particle algorithm has been developed that, with minimal methodical complexity, offers a guide to particle identification. Light microscopic–morphological as well as enzyme–histochemical characteristics and polarization–optical properties have been defined. Particles are characterized in accordance with a dichotomous principle. Based on these criteria, identification and validation of the particles was carried out in 105 joint endoprosthesis pathological cases. A particle score is proposed that summarizes the most important information for the orthopedist.

Der vorliegende Artikel zeigt anhand klinischer Beispiele verschiedene Komplikationen bzw. Erscheinungsbilder bei Patienten, die mit einer Metall-Metall-Gleitpaarungs-Prothese versorgt wurden. Wir empfehlen eine jahrliche klinische Kontrolle aller Patienten, die mit einer Metall-Metall-Gleitpaarung mit einer Kopfgrose ab 36 mm versorgt wurden. Bei allen klinisch auffalligen Patienten sollte die Metallkonzentration von Chrom und Kobalt im Blut gemessen werden und eine MRT-Untersuchung mit metallartefaktreduzierter Sequenz (MARS) oder, wenn dies nicht moglich ist, eine Ultraschalluntersuchung durchgefuhrt werden. Bei der klinischen Untersuchung muss gezielt nach asymptomatischen lokalen Schwellungen oder Verhartungen gesucht werden. Anamnestisch sollten kardiovaskulare, neurologische, endokrinologische (besonders Schilddruse) und renale Funktionsstorungen erfragt werden.

Bei gelenkimplantatallergischen/toxischen Fragestellungen als Ursache fur ein Endoprothesenversagen ist die Neosynovialis/periprothetische Membran („synovial-like interface membrane“, SLIM) gemas der erweiterten SLIM-Konsensus-Klassifikation zu klassifizieren: Typ I, Partikelerkrankung, so genannte „aseptische Lockerung“; Typ II, bakterielle Infektion, so genannte „septische Lockerung“; Typ III, Kombination von bakterieller Infektion und Partikelerkrankung; Typ IV, mechanische Ursachen und funktionelle Storungen; Typ V, ossare Pathologien; Typ VI, endoprothesenassoziierte Arthrofibrose; Typ VII, allergische/immunologische/toxische Reaktionen auf Implantatmaterialien. Die histopathologische Identifikation der Prothesenmaterialpartikel erfolgt gemas des Partikelalgorithmus nach Krenn. Histopathologisch sind die Veranderungen bei Verdacht auf Allergie/Toxizitat des Implantatmaterials zwar charakteristisch, lassen aktuell aber keine eindeutige Unterscheidung zwischen primar toxischen und primar immunologischen Reaktionen zu. Die charakteristischen Veranderungen umfassen den Partikelnachweis, eine ausgepragte lymphozytare, plasmazellulare und makrophagozytare Infiltration, Nekrosen und Granulome bzw. granulomartige Strukturen. In der Maximalauspragung wird dieser Befund als sog. inflammatorischer Pseudotumor bezeichnet. Da Lymphozyteninfiltrate in der SLIM vom Typ I und Typ IV nicht notwendigerweise Ausdruck einer implantatmaterialallergischen Reaktion oder einer Toxizitatsreaktion sind und bislang keine beweisenden zellularen Marker einer pathogenen implantatallergischen Reaktion fur das Gelenkendoprothesenversagen definiert sind und der genaue immunologischen Zusammenhang ungeklart ist, kann die Diagnose einer allergischen Typreaktion/toxischen Reaktion auf Implantatmaterialien in einer SLIM nur im Kontext von histopathologischen, dermatologischen, allergologischen und klinisch-orthopadischen Befunden gestellt werden. Gewebeproben sollten aus verschieden Regionen (SLIM, prothesennah und -fern und eine getrennte Entnahme von Knochengewebe) entnommen werden, um eine suffiziente histopathologische Diagnose zu ermoglichen.

Die Frage nach der Allergiediagnostik kann sich vor einer Implantation oder bei komplikationsbehafteten Implantaten ergeben. Vor Implantation wird nur bei anamnestischen Hinweisen eine mogliche Metallallergie oder Allergie auf potenzielle Knochenzementkomponenten im Epikutantest (ECT) abgeklart. Eine „prophylaktisch-prophetische“ Vertraglichkeitstestung macht keinen Sinn. Bei komplikationsbehafteten Implantaten empfehlen sich nach Ausschluss haufiger Beschwerdenursachen (speziell der Low-grade-Infekt) als Basisallergiediagnostik der ECT mit der (Ni-, Co-, Cr-Praparationen enthaltenden) Standardreihe und Knochenzementkomponenten sowie als weiterer Schritt die histologische Untersuchung von periimplantarem Gewebe. Diese kann eine lymphozytar betonte periimplantare Entzundung zeigen. Erganzende Information liefern als wissenschaftliche Methoden der Lymphozytentransformationstest (LTT) zur Metallsensibilisierung und die periimplantare molekulare Zytokinanalyse zum Entzundungsmuster.

Die erweiterte Klassifikation der periprothetischen Membran („synovial-like interface membrane“, SLIM) umfasst die Gesamtheit der pathologischen Veranderungen, die als Folge der endoprothetischen Versorgung groser Gelenke auftreten konnen und zu einer Reduktion der Prothesenstandzeit fuhren. Hierzu gehoren die etablierte Konsensusklassifikation der SLIM, mit der sich die aseptische und septische Prothesenlockerung in 4 histologische Typen einteilen lassen, sowie histopathologische Kriterien fur weitere Pathologien: Endoprothesen-assoziierte Arthrofibrose, immunologische/allergische Befunde und ossare Pathologien. Diese Erweiterung stellt eine Grundlage fur die histopathologische Diagnostik des gesamten Spektrums von Gelenkendoprothesen-assoziierten Erkrankungen dar und eignet sich als Basis fur eine standardisierte Diagnostik und atiologische Abklarung des Endoprothesenversagens und auch als Datenstandard fur Endoprothesenregister, insbesondere fur Register, die auf Routinedaten basieren (z. B. Deutsches Endoprothesenregister).

In the histopathological particle algorithm polyethylene (PE) particles with maximum lengths of more than 100μm - called PE supramacroparticles - are identified exclusively for knee joint and hip prostheses. However, a definitive characterisation, detection in all joint localisations and a causal clarification of the pathogenesis are lacking. In this study a total of 175 SLIM (synovial-like interface membrane) cases with PE supramacroparticles of knee joint prostheses (n=89), hip joint prostheses (n=44), ankle joint prostheses (n=36) and prostheses in three localisations of the upper extremities (n=6) were systematically investigated. The arithmetic mean of the particle length varied greatly within the prosthesis types. This had a significant positive correlation with the prosthesis lifetime and negative correlation with the date of implantation. It can be concluded that both the lifetime and the time of implantation have an influence on the particle length. The prostheses with supramacroparticulate damage moreover showed a clearly reduced survival rate compared with other data published on the prosthesis lifetime. The material wear therefore could not be attributed solely to the usual fatigue factors. Since loosening of the prostheses, decentring of the PE components or damage to the PE inlay existed in all cases, mechanical dysloading seems to be the most probable cause of PE supramacroparticle genesis. Due to the striking length and for demarcation from PE macroparticles, the term supramacroparticulate PE is proposed for a length of more than 100μm. In the extended histopathological particle algorithm supramacroparticulate PE has been included in the macroparticles category and should be taken into account and interpreted causally in histopathological diagnostics of joint prosthesis failure.

Introduction Adverse reactions to metal debris often indicate revision surgery in metal-on-metal (MoM) hip arthroplasty and an exchange of the MoM bearing into either a metal on polyethylene or a ceramic-on-polyethylene articulation. At the moment the removal of the entire implant system is the most reasonable method. In order to avoid bone loss caused by the removal of a well-fixed acetabular component, the purpose of this study was to measure the stability of a cemented polyethylene (PE) cup in an acetabular hip resurfacing component and to examine if such a method could be suitable for clinical use. Methods PE cups were cemented into 2 different hip resurfacing components and biomechanical tests were applied to measure failure torques under lever out and rotational load. Results In all cases failure of the interface between the resurfacing components and the cement layer occurred at a very low load (0.14 Nm-61.50 Nm). Discussion The early failure occurred due to lacking interdigitation of cement and the polished metal surface. Thus we warn against cementing a PE cup into acetabular hip resurfacing components for clinical use.

Nach Ausschopfung der rheumatologischen konservativen und medikamentosen Therapiemoglichkeiten von degenerativen und entzundlichen Gelenkerkrankungen besteht die endoprothetische Gelenkversorgung als eine wichtige Option, um die ursprungliche Lebensqualitat wiederherzustellen. Die Arthrofibrose stellt eine schwerwiegende fibrosierende Erkrankung der Synovialis nach Endoprothesenimplantation dar. Weder das morphologische Substrat in der Synovialis noch histopathologische Kriterien sind hierfur beschrieben. Ziel war es, anhand von Revisionseingriffen gewonnener Gewebeproben das histopathologische Substrat der Arthrofibrose zu beschreiben und histologische und immunhistochemische Kriterien der Arthrofibrose festzulegen. Histopathologisch zeigte die Arthrofibrose eine Synovialitis mit unterschiedlich ausgepragter Fibrosierung ohne erkennbare Ossifikation und ohne bzw. minimaler Abriebpartikelreaktion (sog. Synovialitis vom arthrofibrotischen Typ, SAT). Es wurde ein 3-stufiges Graduierungsschema fur die SAT festgelegt, das sich an der zellularen Dichte des fibrosen Gewebes (sog. Fibroblastenzellularitat) orientiert. In den untersuchten 191 SAT-Fallen ergab sich in 24,1% (n = 46) Grad 1, in 51,8% (n = 99) Grad 2 und in 24,1% (n = 46) Grad 3. Die Vergleichsgruppe bestand aus 29 Fallen von Synovialitis des Indifferenztyps (Typ IV). Fasste man SAT Grad 2 und 3 zusammen, d. h., der Abstand der Fibroblasten zueinander betragt weniger als 2 Zelllangen, so war der Unterschied der Fibroblastenzellularitat im Vergleich mit der Typ-IV-Membran signifikant (p

In knee arthroplasty patients with complications not explained by classical mechanisms, like infection or malalignment/malposition, the role of hypersensitivity to implant materials may be questioned. In 10 such patients with and 5 without metal sensitization, a combined evaluation of periimplant histology and cytokine expression, and microbiological analysis was done. In the 10 metal allergics, outcome after revision with alternative "hypoallergenic" materials (9×titanium-based, 1×oxinium-based) was evaluated. In the metal-allergic patients, scattered, partly dense T-lymphocytes were seen in periimplant tissue and there were no signs of infection. Predominant IFN-γ expression and the improvement in the postoperative WOMAC scores (mean preoperative score, 40.4; postoperative score, 55.58) supported hypersensitivity as the symptoms elicitor.

Hintergrund Revisionseingriffe an der Hufte sind komplizierte Operationen, weil die Qualitat des Femurs zumeist durch Substanzschadigungen reduziert ist. Die Verankerung der Prothesen mit einer wirkungsvollen Primarstabilitat stellt somit eine grose Herausforderung fur den orthopadischen Chirurgen dar.

This article aims to clarify the influence of design- and manufacturing-related parameters on wear of metal-on-metal (MoM) joint bearings. A database search for publications on wear simulator studies of MoM bearings was performed. The results of published studies were normalized; groups with individual parameters were defined and analyzed statistically. Fifty-six investigations studying a total of 200 implants were included in the analysis. Clearance, head size, carbon content, and manufacturing method were analyzed as parameters influencing MoM wear. This meta-analysis revealed a strong influence of clearance on running-in wear for implants of 36-mm diameter and an increase in steady-state wear of heat treated components.

Metal-on-metal joint bearings are being increasingly used for total hip arthroplasty. Previous results from simulator tests to determine wear of metal-on-metal bearings exhibited high fluctuations. Consequently, wear tests had to be performed for a long period of time to achieve stable values. The aim of this study was to establish a method for the precise measurement of wear of metal-on-metal bearings. Wear was determined by analyzing the concentrations of particles and selected elements in the test medium (serum) using high resolution-inductively coupled plasma-mass spectrometry (HR-ICP-MS). The procedure was first validated and compared to gravimetric measurements on two different implant designs and then applied in wear tests on four total hip resurfacing implants. The validation showed a significant reliability of the HR-ICP-MS method (p ≤ 0.02). The final wear test revealed that the HR-ICP-MS method can precisely detect very low wear rates and accurately characterize alterations in wear progression. The duration of simulation can be reduced due to the high detection power and low fluctuation in HR-ICP-MS wear determination analyses. This approach is suitable for test implants with extremely low wear rates.

Background: Total hip arthroplasty without cement is frequently performed in young active patients, but only limited outcomes data are available after durations of follow-up of more than fifteen years. Methods: We retrospectively evaluated the clinical and radiographic results of a consecutive series of 154 total hip arthroplasties (in 141 patients) performed with an uncemented grit-blasted straight tapered titanium femoral stem combined with a threaded socket in patients under the age of fifty-five years. The median duration of follow-up was seventeen years. Clinical results were evaluated with use of the Harris hip score. The canal fill index was used as the criterion to determine the adequacy of stem sizing. Kaplan-Meier survivorship analysis was performed to predict long-term outcomes. Results: The stem was undersized, with a canal fill index of ≤80%, in forty-one hips (27%). Late aseptic loosening of the stem occurred in four femora, and the femoral component was undersized in all four. These four stems were stable for ten years and then underwent progressive subsidence, which was associated with pain. Five stems were revised because of a late postoperative periprosthetic fracture following trauma. Localized proximal femoral osteolysis was seen in seven hips without signs of loosening. Survivorship of the stem with revision for any reason as the end point was estimated to be 90% (95% confidence interval, 87% to 97%) at twenty years. Survivorship with aseptic loosening as the end point was estimated to be 95% (95% confidence interval, 91% to 99%) at twenty years. Sixty-seven (44%) of the threaded uncemented acetabular components were revised during the follow-up period. Conclusions: After a minimum duration of follow-up of fifteen years, the survival of this type of femoral component is excellent in individuals younger than fifty-five years. The main mode of stem failure was a periprosthetic fracture due to trauma, or late aseptic loosening in a small percentage of the hips in which the femoral implant was undersized. The high rate of failure of the acetabular components was attributable to a poor design that is no longer in use. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

In Kasuistiken wird uber Falle von Metallimplantatallergie berichtet, wahrend grosere Untersuchungen zu Haufigkeit und Auslosern fehlen. Wir betreuen seit 5 Jahren ein Metallimplantatallergieregister, in das wir Daten aus unserer Spezialsprechstunde (Munchener Implantatsprechstunde) und aus eingesandten Dokumentationsbogen eingeben. Erfasst werden Anamnese, Klinik und Allergietestergebnisse bei Patienten mit Verdacht auf Osteosynthesen-/Endoprothesenmaterialunvertraglichkeit. Unter den derzeit 239 Patienten stehen als Beschwerden Schmerzen (68,2%), Schwellung (42,1%) und Rotung (33,5%) im Vordergrund; 29,6% der Patienten weisen eine Kontaktallergie gegen Metalle auf, 24,8% gegenuber potentiellen Knochenzementkomponenten. Sonderkonstellationen wie persistierende Entzundungsreaktionen auf Metallpartikel bei Nickel-/Kobaltallergie oder Beschwerdefreiheit nach Wechsel auf Alternativmaterialien werden erkennbar. Bei Verdacht auf Implantatunvertraglichkeit sollte nach Ausschluss von Differenzialdiagnosen wie Infekt oder mechanisches Versagen auch eine allergologische Diagnostik erfolgen, zu der ein Epikutantest unter Einschluss einer Knochenzementreihe gehort.

Modular neck implants are an attractive treatment tool in total hip replacement. Concerns remain about the mechanical stability and metal ion release caused by the modular connection. Five different implant designs were investigated in an experimental set-up. In vivo conditions were simulated and the long-term titanium release was measured. Finally, the modular connections were inspected for corrosion processes and signs of fretting. No mechanical failure or excessive corrosion could be identified for the implants tested. The titanium releases measured were extremely low compared to in vivo and in vitro studies and were not in a critical range.

Bone stock losses in cementless femoral stem revisions compromise a stable fixation. The surgeon has to rely on his wealth of experience in deciding which stem shape to use. The aim of our study was to compare the primary rotational stability of cylindrical and conical revision hip stems subjected to femoral defects. Four current prostheses (two cylindrical, two conical) were implanted into four synthetic femora. Micro-motion was measured under torque application and femoral neck osteotomy and segmental AAOS Type I and III defects were simulated. The relative movements of all prostheses were significantly influenced by the extent of bone loss (p

Moderne Metall-Metall-Gleitpaarungen zeichnen sich durch einen sehr geringen Verschleis der Gelenkpartner aus. Sie setzen jedoch durch die Reibung an den artikulierenden Oberflachen Partikel und Ionen frei, die sich im Gelenk und im gesamten Organismus verteilen. Insbesondere in der Einlaufphase werden vermehrt Metallpartikel produziert. Die freigesetzten Ionen fuhren potentiell zu zytotoxischen, kanzerogenen und allergischen Reaktionen, die sich dann lokal oder systemisch auf die Patientengesundheit auswirken konnen. Vor allem die Hypersensitivitat auf die in der Legierung enthaltenen Metallionen wird von vielen Operateuren als bedenklich angesehen. Die Inzidenz dieser implantatbezogenen Komplikationen wird zum jetzigen Zeitpunkt als sehr gering eingeschatzt, jedoch kann es im schlimmsten Fall zu einem fruhzeitigen Versagen des Implantats kommen. Weil auch die alternativ einsetzbaren Gleitpaarungen (Keramik-Polyethylen, Keramik-Keramik) mit z. T. nicht unerheblichen Komplikationen einhergehen konnen, ist bis heute keine abschliesende Beurteilung zur Risikoeinschatzung moglich.

Es wird ein Prazisionsmesverfahren (Auflosung: 0.1 μm) zur Mikrobewegung von Huftendoprothesen beschrieben, das die raumliche Bewegung der Prothese und simultan die Verbiegung des Schaftes in Abhangigkeit des raumlichen Kraftsystems (drei Kraft- und drei Drehmomentkomponenten) registriert. Damit wurde in vitro fur eine zementierte Prothese untersucht, welche Auswirkungen vollstandige Ablosung des Schaftes vom Zement auf Biegung und Mikrobewegung hat. Festsitzende und gelockerte Prothese unterscheiden sich bezuglich der mechanischen Stabilitat nur hinsichtlich der Rotation um die Langsachse: Die gelockerte Prothese hat eine 2,5 fach erhohte Torsionsflexibilitat. In beiden Fallen bewegt sich der Schaft nicht wie ein starrer Korper: er biegt sich je nach Art des Drehmomentangriffs. Fur das Ausmas von Biegung und Mikrobewegung sind nicht so sehr die Krafte selbst als die durch sie hervorgerufenen Drehmomente verantwortlich. Bei vollig gelockertem Schaft bewegt sich die Schaftspitze nur in- bzw. extrusiv: Die Horizontalbewegung liegt unter der Auflosung. Die Mesergebnisse lassen sich dahingehend interpretieren, das Schafte, die frei im Zementkocher stecken, die Zementknochenschicht weniger schadlich beanspruchen als festsitzende Schafte. A precision measurement method (resolution: 0.1 μm) is described that simultaneously tracks spatial movement of the prosthesis and its bending as a function of the spatial force system (three force and three torque components). With this technique, we examined the effects of complete Separation between shaft and cement on bending and micromovement. With regard to mechanical stability a completely tied and a loosened prosthesis differ only in respect to torsional load: the loosened prosthesis bears a 2.5-fold larger torsion fiexibility. In both cases the shaft does not move like a rigid body: it bends up or down depending on the way the torque acts. It is the torques (that are produced by the forces) rather than the forces themselves that are responsible for the extent of micromovement and bending. In the completely loosened shaft, the sbaft's apex only moves either intrusively or extrusively according to the directions of the torque vector: the horizontal movement cannot be resolved. The data suggest that shafts that are freely mounted into its cement quiver load the cement layer in a less damaging fashion than tied shafts.

UNLABELLED Since 1979 prenatal ultrasonography is a screening method in Germany. The examination of head, thorax and femur is now established as a routine method. AIM OF THE STUDY The evaluation of the effectiveness and the consequences of an early prenatal diagnosis of foetal limb deficiencies. METHOD From 1989-1994 we had 403 children with 207 minor or 196 major limb deficiencies. Questionnaires were sent to those 196 parents of children with major diseases 134 cases (68%) of children with limb deficiencies could be analysed. The average age of the mother at birth was 27.5 years and the age of the father was 30.5 years. RESULTS 61 children had deficiencies of the upper limb. another 61 of the lower limbs and 12 had combined defects of the limbs. The mothers had 5.6 (1-15) prenatal ultrasounds examinations. In 63% (n = 82) these were performed by the obstetric practitioners, in 30% in departments of obstetrics and 7% in a university hospital. In 5.2% only, the limb deficiency was diagnosed antenataly. CONCLUSION If there are any unclear findings the women should be sent to a centre of prenatal diagnostics. In cases of congenital deficiencies of the limbs there is the possibility] for the parents to combined to combined consultation of the obstetrician, the human genetic and the orthopaedic to plan the treatment and talk about all consequences.

In a controlled prospective randomized study we evaluated the effectiveness of intraarticular injected hyaluronic acid regarding the changes in the parameters dynamometry, synovial oxygen partial pressure, intraarticular temperature and the knee joint function (Lequesne score). We examined 18 patients with osteoarthritis in both knee joints (Kellgren classification II or III according to x-ray) in right/left comparison. The evaluated parameters were measured before and after a 5-week treatment phase with 5 intraarticular injections (one injection per week). With regard to the efficacy results changes in dynamometric measurement for flexion and extension (for all angular velocities) and Lequesne-score indicate a marked improvement after treatment with hyaluronic acid. The differences between treated and untreated knee were significant. In extension the p-value was 0.0008 and in flexion p = 0.0015. The p-value of the Lequesne-index between the verum and control group was p = 0.0002. After treatment values for oxygen pressure were higher than at baseline and for the intraarticular temperature a small decrease at the end of the treatment phase was documented. The intraarticular injection of hyaluronic acid is effective and safe in the treatment of patients with gonarthrosis. The treatment resulted in a functional improvement of the knee joint and had a good pain-lowering effect in patients suffering from gonarthrosis.

While bone cement debris has been recognised as an important factor in aseptic loosening of prosthetic components, the interest is now focused on the impact of debris and wear-off particles from polyethylene and metal alloys. As an optimal lubrication cannot be generated yet, direct contact between the components produces wear particles, depending on the materials used. The materials reported on include alloys based on iron, cobalt, titanium and polyethylene, bone cement and ceramics. These all show the problem of debris, friction, corrosion (except ceramics) and load failure, related to the work up process. The practitioner is given an overview and tables are presented to compare the used material.

A wealth of commercially available hip endoprotheses makes it difficult for the practitioner to choose the best implant for each individual case. In a multi-centre study, in which 22 hospitals took part, a cementless stem was used 1172 times and was combined with 3 different cementless cup components. The follow up period ranged from 1-8 years. In 321 cases the spherical Mecring cup, in 208 cases the spherical CLS-expansion cup and in 643 cases the conical Weill-ring was implanted. The predominant indication for the THR was primary coxarthrosis (767 patients). Evaluation of clinical results was based on the Merle d'Aubigne score. Good or excellent results were found in 82% for the Mercring, in 85% for the Weill-ring and in 91% when the CLS-expansion cup was used. Whereas 88% of the patients with the Mecring or Weill-ring had minimal or no pain, 94% of the patients had minimal or no pain when the CLS-expansion cup was implanted. Aseptic loosening was found in 1.25% for the Mecring and 1.5% with the Weill-ring. In the CLS-expansion cup group, 2 cases with radiological signs of loosening were seen, but neither patient required revision. The CLS-expansion-cup with the press fit system shows better medium follow-up results in this study, than the Mecring or Weill-ring systems.

Oxygen partial pressure is directly related to the vascularisation of different tissues. Different investigations in tissue (muscle, kidney, brain, heart, bone etc.) proved this correlation. The development of a special flexible microcatheter named Licox enables us to do measurements of intraarticular oxygen partial pressure under physiological and pathological conditions for the first time. The aim of this study was to examine the influence of different knee joint stresses on the intraarticular oxygen partial pressure under normal conditions and in osteoarthritis. The results showed that the different exercise patterns influence the intraarticular oxygen partial pressure. Patients with osteoarthritis showed a lower increase of the intraarticular oxygen partial pressure compared to the control group. This phenomenon is directly correlated to degree velocity of the isokinetic exercises. The same findings occur under ergometric conditions. The method permits functional, intraarticular in vivo measurements under different exercise patterns. For the very first time we were able to measure the influence of the joint movement on the intraarticular process of nutrition under physiological and pathological conditions. Different therapy concepts in osteoarthritis can be evaluated directly in vivo for the first time.

Aseptic loosening of endoprosthesis is the most important problem in total hip arthroplasty. The diagnosis of aseptic loosening is based on anamnesis, the clinical findings, the radiography and scintigraphy. Despite the multitude of diagnostic possibilities it is still a problem to get an exact and early diagnosis. The process of loosening in the bone interface always leads to a change of bone structure of the surrounding bone tissue. In a prospective study we measured biochemical markers of bone metabolism in serum and urine to evaluate a possible change occurring parallel to endoprotheic loosening. 37 patients with severe signs of loosening (later intraoperatively confirmed) and 30 patients without any clinical or radiological signs of loosening (control group) were induced. Gender, age and model of endoprosthesis were similar in both groups. Parameters of bone formation (osteocalcin, alkaline phosphatase, procollagen I C-terminal extension peptide) and bone resorption (Cross-linked n-terminal telopetide) were measured. The cross-linked n-terminal telopetide (NTX) was significant increased in the loosening group (p < 0.001). Of the measured bone formation markers only osteocalcin showed a significantly higher level in patients with endoprosthetic loosening (p < 0.002). All other measured parameters of the bone metabolism showed no significant differences between the both groups. Our results show, that biochemical markers can provide relevant information of endoprosthesic loosening. We are now analysing in a prospective longitudinal study whether these parameters are also suitable to detect early endoprosthetic loosening.

The principles of proximal fixation of cementless endoprostheses is established already. This theory was the subject of the present multi-center study of 22 clinics. Between 1984 and 1992 all 1830 patients with an uncemented CLS press-fit stem had a clinical and radiological follow-up examination and computer documentation. The evaluation of the clinical results are based on the Merle d'Aubigne score. In 91% we found a good or excellent result. For the remainder of patients (9%) with a score less than 14 each case has been especially analysed. The incidence of femor component loosening was less than 1% within the average follow-up time of 2.5 years. The medium-term results with the uncemented CLS press-fit stem confirmed the idea of proximal load induction on the femur.

Intolerance reactions to endoprostheses may lead to allergological diagnostics, which focus mainly on metal allergy. However, bone cement may also contain potential allergens, e.g. acrylates and additives such as benzoyl peroxide (BPO), N,N-dimethyl-p-toluidine, hydroquinone, and antibiotics (particularly gentamicin). In the Munich implant allergy clinic, we found that 28 of 113 patients (24.8%) with cemented prostheses had contact allergies to bone cement components, mostly to gentamicin (16.8%) and BPO (8.0%). The clinical significance of test results cannot always be shown, but we still recommend including bone cement components in the allergological diagnostics of suspected hypersensitivity reactions to arthroplasty.

Materials used in osteosynthesis or artificial joint replacement are usually well tolerated. Complaints after such operations are mostly related to infection or mechanical problems but may also be caused by allergic reactions. The latter encompass skin changes, e.g., eczema, delayed wound/bone healing, recurrent effusion, pain, or implant loosening. In contrast to the high incidence of cutaneous metal contact allergy, allergies associated with implants are a rare condition. However, epidemiological data on the incidence of implant-related allergic reactions are still missing. Typical elicitors are nickel, chromium, cobalt, and constituents of bone cement (acrylates und additives such as gentamicin or benzoyl peroxide). After exclusion of the most common differential diagnoses, allergy diagnostic procedures are primarily based on patch tests including a metal and bone cement component series. Additional analysis of periimplant tissue is recommended. However, further studies are necessary to show the significance of the histologic findings and the role of the lymphocyte transformation test (LTT). Which combinations of factors will induce allergic sensitization to implants or trigger periimplant allergic reactions in the case of preexisting cutaneous metal allergy is still unknown. Titanium-based osteosynthesis materials are recommended for metal allergic patients. In elective hip replacements, a ceramic/polyethylene (PE) articulation should be used, and in knee replacements "alternative materials". If a regular, potentially applicable CoCr/PE articulation is preferred, the patient must be well informed and must give his/her written consent.

The object of the present study was to determine the incidence of metal sensitivity in patients with joint replacement arthroplasties before and after surgery and whether this is of significance as regards the final outcome of the operative procedure. A questionnaire-based survey involved 1,335 patients with an average age of 61 years and joint replacement arthroplasties before and after surgery. A history of dermal sensitivity to metal was given in 99 (7%) patients with almost equal frequency in the pre- and postoperative groups (7.6 vs 7.2%). In only 27 of 99 cases was the metal sensitivity recorded in the patient chart. In 46 cases investigation was done after knee or hip replacement arthroplasty with an average implant time in situ of 68 months. In 32 of 46 patients a sensitivity to the implanted material was known and they did not show any complications related to the metal sensitivity.It is currently unclear whether metal sensitivity could be induced by joint replacement arthroplasties and it remains uncertain whether loosening or infection causes the sensitization as a consequence of increased release of metal ions or vice versa. To draw further conclusions considerably more detailed studies involving more patients are clearly indicated.

New prosthesis designs should provide either superior function or durability. Before long time follow up studies are started it should at least prove its effectiveness in clinical outcomes. Therefore we have studied the early clinical results of a new mobile bearing total knee prosthesis (e.motion; Aesculap) in comparison with our established fixed-bearing device (PFC; DePuy) in a matched-pair analysis.About 30 consecutive patients received the new mobile bearing device and were matched with patients who received the PFC prosthesis according to age, gender, weight, axis and preoperative AKS-score. Outcomes were measured using the scores that are routinely documented in our arthroplasty register namely the American Knee Society Score (AKSS), the Oxford Knee Score (OKS), Functional Questionnaire of Hannover for Osteoarthritis (FFbH-OA), range of motion (ROM) and knee pain before and 2 years after the operation.No statistical differences could be found neither preoperative nor postoperative. Nevertheless the mobile bearing device had a slightly better ROM and function score.This new device proved to be at least as effective in early clinical outcome as the established fixed bearing prosthesis. It has to be awaited whether it is advantageous in the long run.

Nickel, chromium, and cobalt in stainless steel and Cobalt-chrome-molybdenum (CoCrMo) alloys may induce allergy. The objectives of this study were to evaluate surface coating regarding ion release, patch test reactivity, and arthroplasty performance. Materials and methods included patch test in 31 patients with metal allergy and 30 patients with no allergy to stainless steel and CoCrMo disks that are uncoated or coated by titanium nitride/zirconium nitride (TiN/ZrN). Assessment include atomic absorption spectrometry of released nickel, cobalt, and chromium from the disks after exposure to distilled water, artificial sweat and culture medium. Results showed that both coatings reduced the nickel and chromium release from stainless steel and CoCrMo disks and mostly the cobalt release from the disks (maximally 11.755 µg/cm 2 /5 d to 1.624 by Ti-N and to 0.442 by ZrN). Six of the 31 patients with metal allergy reacted to uncoated disks, but none reacted to the coated disks. The current authors report on exemplary patients with metal allergy who had symptom relief by revision with surface-coated arthroplasty. The authors concluded that the surface coating may prevent cutaneous and peri-implant allergic reactions. [ Orthopedics . 2016; 39(3):S24–S30.]

Inferior survival of cemented total hip arthroplasty has been reported after previous femoral osteotomy. We previously presented 5-15 years results of uncemented femoral stems for this subgroup of patients. The purpose of the present study was to re-evaluate that same patient group at 10-20 years follow-up.Forty-eight hips in 45 patients had undergone conversion THA for a failed intertrochanteric osteotomy of the hip after a mean of 12 years (2-33 years). Mean time of follow-up was 16 years (10-20 years).At the latest follow-up five patients had died (five hips), and one patient (one hip) remained lost to follow-up. Compared to the previous evaluation, one more patient required femoral revision for aseptic loosening giving a total of four patients (four hips) with femoral revision--one for infection and three for aseptic loosening of the stem. Survival of the stem was 91% at 15 and 20 years respectively; survival with femoral revision for aseptic loosening as an end point was 93%. The median Harris-Hip-Score at final follow-up was 76 points (previously 80 points). Radiolucent lines in Gruen zones 1 and 7 were present in 20 and 17% of hips, respectively. Radiolucencies in other zones were not detected. There was no radiographic evidence of femoral osteolysis, stress-shielding or loosening.The long-term results with this type of uncemented tapered titanium femoral component after proximal femoral osteotomy remain encouraging and compare favorably to those achieved in patients with regular femoral anatomy.

Femoral defects often make it difficult to achieve sufficient fixation of the stem during revision surgery. No clinical studies comparing modular stems are available and differentiated recommendations are rare. The aim of this study was to compare the fixation of different revision stems in an experimental and standardised manner. Segmental AAOS type I and III defects were reproduced in four femur pairs and two modular stems of different shape (cylindrical and conical) were implanted. Interfacial stem–bone movements were measured under axial torque application to analyze the stem fixation depending on defect extension. Both stems showed adequate fixation in AAOS type I defect. The defect extension significantly reduced the fixation of both implants. The fixation pattern changed significantly for the cylindrical-shaped stem but was maintained for the conical-shaped stem. Shape as well as the extension of femoral defect have an impact on primary fixation. A type I defect seems to be bridgeable for both stems albeit in a different way. In contrast, stem-demanding activities during the healing phase have to be avoided for the conical-shaped stem in a type III defect, whereas the cylindrical-shaped stem has already ceased to be sufficiently stable in this case.

Bone cements based on polymethylmethacrylate are typically used for fixation of artificial joints. Intolerance reactions to endoprostheses not explained by infection or mechanical failure may lead to allergological diagnostics, which mostly focuses on metal allergy. However, also bone cement components may provoke hypersensitivity reactions leading to eczema, implant loosening, or fistula formation. Elicitors of such reactions encompass acrylates and additives such as benzoyl peroxide, N,N-dimethyl-p-toluidine, hydroquinone, or antibiotics (particularly gentamicin). Upon repeated contact with bone cement components, e.g., acrylate monomers, also in medical personnel occasionally hand eczema or even asthma may develop. Therefore, in the case of suspected hypersensitivity reactions to arthroplasty, the allergological diagnostics should include bone cement components.

For treating patients with scoliosis orthopaedic surgeons need diagnostic imaging procedures in order to provide answers about a possible underlying disease, choice of treatment, and prognosis. Once treatment is instituted, imaging is also critical for monitoring changes of the deformity so as to optimize therapy. The combined effort of orthopaedic surgeons and radiologists helps detect treatable causes of scoliosis at an early stage, define the need and timing for surgery, and ensure that every precaution is taken to minimize the risks of surgery. Neurosurgical causes, with particular reference to spinal cord tumours and syringomyelia, need to be addressed before scoliosis surgery can be contemplated.

STUDY DESIGN We retrospectively studied 24 consecutive pediatric patients with lumbar kyphosis due to myelodysplasia who had received corrective surgical treatment with the Warner and Fackler technique from 1994 to 2004. OBJECTIVES The purpose of the study was to evaluate the technical problems and outcome and to identify complications of this treatment modality, especially regarding the biomechanics. SUMMARY OF BACKGROUND DATA The management of lumbar kyphosis (8%-20%) in conjunction with myelodysplasia is difficult. In 1993, Warner and Fackler presented an elegant surgical technique, which was used here. METHODS Corrective surgery was performed in 24 patients with an average preoperative lumbar kyphosis of 124 degrees . The correction was achieved by kyphectomy combined with stabilization using rods and wires as described by Warner and Fackler. Outcome was rated and complications were identified using data from the clinical records. For biomechanical analysis of the surgical construct, a force model was developed. RESULTS The mean extent of lumbar kyphosis could be corrected from 124 degrees before surgery to 43 degrees after surgery. Biomechanical analysis showed that inadequate correction results in implant failure. CONCLUSION Surgery should always be performed with the intention to reestablish the sagittal profile inasfar as possible so as to reduce the risk of implant failure.

Inferior survival of cemented total hip arthroplasty has been reported after previous femoral osteotomy. The purpose of this study was to evaluate the long-term survival of uncemented stems after femoral osteotomy. Forty-eight hips in 45 patients had undergone conversion THA for a failed intertrochanteric osteotomy of the hip after a mean of 12 years (2–33 years). Mean time of follow-up was 11 years (5–15 years). At follow-up, two patients (three hips) had died, and one patient (one hip) was not located. Three patients (three hips) underwent femoral revision—one for infection and two for aseptic loosening of the stem. Survival of the stem was 94% at 10 years, and survival with femoral revision for aseptic loosening as an end point was 96%. The median Harris Hip Score at follow-up was 80 points. Radiolucent lines in Gruen zones 1 and 7 were present in 14 and 18% of hips, respectively. Radiolucencies in other zones were not detected. There was no radiographic evidence of femoral osteolysis, stress-shielding or loosening. The results with this type of uncemented tapered titanium femoral component after proximal femoral osteotomy are encouraging and compare to those achieved in patients with regular femoral anatomy.

This study compares the effect of new electronic display systems using endoscopic instruments on intrathoracal maneuvering and targeting under standardized conditions. A 2-dimensional (2-D) vision system is compared with 2 stereoscopic 3-dimensional (3-D) video technologies, called "shutter glasses," and the head-mounted display (HMD) system.Fifteen participants with minor experience (50 operations = beginners) and 15 participants with endoscopic experience (advanced) had to hit 12 electronically conducted wires in a thoracic spine model using 3 different systems (2-D video, 3-D shutter glasses, and 3-D HMD). The sequence was randomly alternated for each participant and repeated 3 times to eliminate the influence of training and concentration.The execution time with the 2-D system (mean time, 95.5 seconds) was shorter than with the HMD (mean time, 107 seconds; P =.001) or the Shutter system (mean time, 101 seconds; P =.002). No significant difference was seen between the 3-D systems (P =.153). The overall look of the missed targets showed statistically no difference between the 3 systems (P =.191). None of the 3 systems showed a statistically significant correlation between execution time and number of missed targets. Regarding the total number of missed targets for advanced and beginner groups, the head-mounted display system in the advanced group showed higher but not statistically significantly higher accuracy.Although the 3-D systems tested for endoscopic surgery did not accelerate the execution speed, the HMD system seems to increase the accuracy for endoscopically experienced surgeons.

Bone resorption in the proximal femur is commonly seen after total hip arthroplasty (THA). With dual energy X-ray absorptiometry (DXA), the amount of bone mass (BMD) after implantation of a total hip stem can be precisely determined. However, prospective evaluation of the change of bone mass around the stem is only available for selected stems and short-term follow-up (up to 36 months). We analyzed BMD in patients who had undergone uncemented THA by DXA. Only patients with good clinical outcome (Merle d' Aubigné score12) were included to obtain normative data for regular bone response. Two separate studies were performed: a prospective longitudinal study over 84 months with baseline values acquired within the first postoperative week (group A) (n = 26 patients) and a separate cross-sectional study, median follow-up 156 (124-178) months (group B) (n = 35 patients). Regions of interest were defined according to Gruen (ROI 1-7) and as net average ROI (net avg) for the periprosthetic femoral bone. After the initial remodeling process (12 months), BMD was compared to the 84-month (longitudinal) and the 156-month (cross-sectional) follow-up values to determine long-term periprosthetic changes of bone mineral density. The longitudinal study (group A), after the initial bone remodeling, showed no relevant further bone loss for women and men with BMD values 1.19 +/- 0.15 and 1.40 +/- 0.19, respectively, 12 months (women 89.8%, men 93.6%), and 1.19 +/- 0.13 and 1.36 +/- 0.18, respectively, after 84 months (women 90.0%, men 91.3%) (P = 0.98, P = 0.08,) respectively. The distribution of the BMD around the stem changed during the first 12 months. The ROIs around the proximal stem (ROI 1 and 7) showed the lowest absolute values at the 12-month follow-up and BMD in ROI 7 decreased most during the further follow-up until 84 months. The cross-sectional study (group B) showed no significant difference in BMD (net avg) values at a median of 156 months follow-up compared to the 12-month values (group A) (women: P = 0.77, men: P = 0.44). Initial BMD, implant diameter, and body mass index did not influence BMD loss (net avg) in this study, whereas age showed a weak correlation with BMD loss. The results show that after the initial remodeling process, no relevant further bone loss (net avg) occurs up to 84 months postsurgery, and values after a median of 156 months are similar. Normative long-term changes in the periprosthetic bone can be demonstrated in defined ROIs after implantation of a tapered corundum-blasted titanium stem with a good clinical result.

Aim: Retrograde cement application is considered an integral part of the modern femoral cementing technique. Both pressurisation and rapid cement application reduce the risk of interface bleeding and blood laminations. In this context cement gun performance has received little attention. Method: In our study we examined the handling characteristics of four different cement delivery systems (Syringe®, Vaku-Mix®, Optivac® and MixOR®-System). To allow for cement viscosity as another variable, six different bone cements (Palacos® R, Palamed G®, CMW 1 Radiopak®, CMW 2000®, Simplex® P, VersaBond®) were used with each system. We recorded cement gun performance and measured extrusion times and maximum cement delivery speeds of all possible combinations (gun/mixing system plus cement type). Results: The fastest cement application could be achieved with the Vaku-Mix® cement delivery system and the corresponding cement gun (Mark III). With regard to cement type, VersaBond® and prechilled Palacos® yielded significantly shorter extrusion times than most of the other cements due to their lower viscosities. Conclusion: Our results have shown significantly different efficacies of commonly used cement delivery systems/guns in clinical routine. Improved systems should be provided by the suppliers.

We evaluated the clinical and radiographic results of the first consecutive 154 implantations of a cementless, double-tapered straight femoral stem (cementless Spotorno (CLS), Sulzer Orthopedics) in 141 patients under the age of 55 (mean 47 (13-55)) years. After a mean follow-up of 12 (10-15) years, 11 patients (11 hips) had died and 7 (7 hips) could not be located. 5 patients (5 hips) underwent femoral revision-1 for infection, 1 for periprosthetic fracture and 3 for aseptic loosening of the stem. The overall survival rate of the stem was 97% at 12 years (95% confidence limits, 93%-100%), and survival with femoral revision for aseptic loosening as an end point 98 (95-100)%. The survival rate of the acetabular components was 78 (71-85)% after 12 years. The median Harris hip score at follow-up was 84 points. None of the patients had thigh pain. Radiolucent lines in Gruen regions 1 and 7 were present in 21 hips (17%). 2 hips had radiolucent lines in regions 2-6 on anteroposterior (AP) radiographs. No femoral osteolysis was detected. The mid- to long-term survival with this type of femoral component is excellent and compares favorably with cemented stems in this age group. However, the high rate of cup loosening and the low Harris hip scores are a concern in this subgroup of young patients.

We evaluated the clinical and radiographic results of the first consecutive 154 implantations of a cementless, double-tapered straight femoral stem (cementless Spotorno (CLS), Sulzer Orthopedics) in 141 patients under the age of 55 (mean 47 (13-55)) years. After a mean follow-up of 12 (10-15) years, 11 patients (11 hips) had died and 7 (7 hips) could not be located. 5 patients (5 hips) underwent femoral revision-1 for infection, 1 for periprosthetic fracture and 3 for aseptic loosening of the stem. The overall survival rate of the stem was 97% at 12 years (95% confidence limits, 93%-100%), and survival with femoral revision for aseptic loosening as an end point 98 (95-100)%. The survival rate of the acetabular components was 78 (71-85)% after 12 years. The median Harris hip score at follow-up was 84 points. None of the patients had thigh pain. Radiolucent lines in Gruen regions 1 and 7 were present in 21 hips (17%). 2 hips had radiolucent lines in regions 2-6 on anteroposterior (AP) radiographs. No femoral osteolysis was detected. The mid- to long-term survival with this type of femoral component is excellent and compares favorably with cemented stems in this age group. However, the high rate of cup loosening and the low Harris hip scores are a concern in this subgroup of young patients.