BACKGROUND AND PURPOSE: Computerized methods have been introduced for more objective quantification of angiographic occlusion rate and coil density as parameters of successful embolization. This study aimed 1) to evaluate this new computerized method for angiographic occlusion rating and coil density calculations by comparison with corresponding histometric parameters from retrieved human aneurysms, and 2) to compare the new computerized method with the present standard of subjective angiographic occlusion rating. MATERIALS AND METHODS: From 14 postmortem-retrieved human aneurysms, angiographic occlusion rate was determined by contrast medium attenuation-gradient distinction on digital subtraction angiographs after Guglielmi detachable coil (GDC) embolization. Angiographic coil density was calculated, approximating aneurysms as ellipsoid and coils as cylindric volumes. On surface-stained histologic ground sections of the respective aneurysms, the occluded aneurysm area and coil area were measured. Then, we calculated and compared the histometric occlusion rates and coil densities with the corresponding angiographic parameters by using the Wilcoxon paired signed-rank test and the Spearman rank correlation. RESULTS: Computerized angiographic occlusion rates (75%–100%) showed good correlation (r = 0.799; P < .01) with histometric occlusion-rates (61%–100%), resulting in no statistically significant differences (P = .2163). With 5.1% (±3.8), the mean difference between computerized angiographic occlusion rates and histometry was substantially lower compared with 10.7% (±8.7) mean difference between subjective angiographic estimations and histometry. Calculated angiographic coil density (13%–32%) significantly differed from histometric coil density (8%–35%; P < .05). CONCLUSIONS: For recanalized aneurysms, computerized angiographic occlusion rating showed better correspondence with histometry compared with subjective angiographic occlusion rating. Clinical application of this new tool may lead to more objective cutoff values for re-embolization indications. The value of coil density calculations seems limited by the approximation of the aneurysms as ellipsoid volumes.

Investigations of a patient with the benign adult form of osteopetrosis (Albers-Schönberg) revealed that the clinical symptoms correlated with a high bone metabolism, high calcium incorporation in bone, increased osteoclast activity and probably reactive increase of calcitonin in the blood.

Investigations of a patient with the benign adult form of osteopetrosis (Albers-Schönberg) revealed that the clinical symptoms correlated with a high bone metabolism, high calcium incorporation in bone, increased osteoclast activity and probably reactive increase of calcitonin in the blood.

Two Durasul highly crosslinked polyethylene liners were exchanged during revision surgery four and five years after implantation, respectively. The retrieved liners were evaluated macroscopically and surface analysis was performed using optical and electron microscopy. A sample of each liner was used to determine the oxidation of the material by Fourier transform infrared spectroscopy. Samples of the capsule were examined histologically.The annual wear rate was found to be 0.010 and 0.015 mm/year, respectively. Surface analysis showed very little loss of material caused by wear. Histological evaluation revealed a continuous neosynovial lining with single multinucleated foreign-body giant cells. Our findings showed no unexpected patterns of wear on the articulating surfaces up to five years after implantation and no obvious failure of material.

Die Osteonekrose des Hüftgelenkes (ON) im Erwachsenenalter stellt noch immer ein nicht gelöstes therapeutisches Problem dar. Neuere Erkenntnisse der Pathophysiologie haben jedoch das Verständnis für den Krankheitsverlauf wesentlich verbessert. Die diagnostischen Möglichkeiten bei der ON wurden in den letzten Jahren durch technische Fortschritte bei den bildgebenden Verfahren deutlich erweitert. Der entscheidende Fortschritt im Verständnis der Pathophysiologie, Früherkennung und Therapieplanung wurde jedoch durch den routinemäßigen Einsatz der MRT erreicht. Unter Verwendung der internationalen ARCO-Stadieneinteilung werden in dieser Übersichtsarbeit die pathomorphologischen und bildgebenden Veränderungen in den einzelnen Stadien der ON beschrieben. Ein diagnostischer Algorithmus bei Verdacht auf ON wird vorgeschlagen. Die Möglichkeiten der konservativen und chirurgischen Behandlungsverfahren bei der ON sind vielfältig, und neue Behandlungsmethoden kommen immer noch dazu. Eine kurze Übersicht über die gängigsten Behandlungsstrategien wird vorgestellt. Am Ende erfolgt eine nach Stadien orientierte Behandlungsempfehlung für die Praxis.

Osteonecrosis of the hip (ON) in the adult is still an unsolved therapeutic problem. New pathophysiological findings have increased our knowledge of the disease course. Technical progress in imaging modalities and a better understanding of pathomorphology have improved the diagnostic procedure. The most significant progress for pathopysiology, early diagnosis and therapeutic decision making has been evolved by the routine use of MR-imaging. Using the international ARCO staging system, the pathomorphological and imaging changes during the different ON stages are described in this review. A diagnostic algorithm for ON is proposed. There are numerous conservative and surgical therapeutic approaches to ON, and the number of these is still increasing. A short overview of the most common therapeutic concepts is given. Finally, recommendations for therapeutic decision making for daily practice are proposed.

Beim suprameatalen Zugang erfolgt die Cochleaimplantatelektrodeninsertion ohne Mastoidektomie und posteriore Tympanotomie, unter Bildung eines klassischen tympanomeatalen Lappens und Bohrung eines suprameatalen Tunnels. Seit 2000 wurde die OP Technik ausführlich vorgestellt. (1,2,3) Weltweit wurden bisher mehr als 500 Implantationen mit dieser OP Technik durchgeführt. Um die Elektrodenlage und die Beziehung zu den cochleären Strukuren zu untersuchen wurden 50 frische humane Felsenbeine mit Elektroden der drei Herstellerfirmen implantiert. Es fanden Combi 40+ und Flex (Med El), Contour und Countour Advance (Cochlear), sowie High Focus und High Res 90K (Advanced Bionics) Verwendung. Die Felsenbeine wurden mit den Elektoden in situ in 200–300µm dünn geschnitten. Die Schnitte wurden anschließend zu 50–100µm dünnen Präparaten geschliffen und poliert. Die histologische Evaluation zeigt, dass sich die Elektroden der einzelnen Hersteller bei suprameataler Insertionstechnik genauso, wie bei konventionellem OP Zugang verhalten. Der suprameatale Zugang ist histologisch verifiziert eine sichere Methode und kann entsprechend der verwendeten Insertionselektrode einen schonenden Zugang in die Cochlea bieten. Weiters zeigt die histologische Aufarbeitung die Unterschiede der einzelnen Elektrodenträger und deren intracochleäre Positionierung.

In this study the authors investigated the results of different designs of cementless THRs using ceramic/ceramic components. The authors analyzed the clinical results taking into account the age of the patients and of the type of implants used and also developed some basic considerations with regard to the interaction between AI2O3 ceramics and human tissue.

In this study the authors investigated the results of different designs of cementless THRs using ceramic/ceramic components. The authors analyzed the clinical results taking into account the age of the patients and of the type of implants used and also developed some basic considerations with regard to the interaction between AI2O3 ceramics and human tissue.

In this study lumbar vertebral bodies with and without disturbed mineralization from a medico-historical collection of the 19th century (housed in the Federal Museum for Pathological Anatomy, Vienna) were investigated, using non-invasive radiological and invasive histological techniques. Macerated, or partly dissected, or fixation fluid conservated skeletal preparations from 61 individuals with known age and gender were examined. The specimens of 37 individuals had gross pathologic alterations from rickets or osteomalacia. The specimens from 24 individuals without Known bone disease served as age-matched controls. Bone structure and mineralization in all specimens were evaluated by non-invasive techniques (conventional radiographs and computed tomography). Thirteen selected specimens from both groups were also analysed by quantitative computed tomography (qCT) and dual-energy X-ray absorptiometry (DEXA). In these cases invasive techniques (light and scanning electron microscopy [backscattered electron (BSE)- and secondary electron (SE)-mode] on surface-stained and carbon-sputtered undecalcified histological ground sections) were applied. Corresponding microradiographs were also used for computer-assisted morphometry. The clinically established method of determination of bone mineral densities (BMD) by qCT and DEXA failed in these historical specimens, but all other non-invasive and invasive techniques were successfully applied and yielded results corresponding to radiological changes and histomorphometric parameters. In the rachitic vertebrae it was not volume densities (bone volume per tissue volume = BV/TV), but numbers of trabeculae (trabecular number = Tb.N.) which were increased, compared to the age-matched vertebral bodies without bone disease. In osteomalacic vertebrae the volume densities (BV/TV) were decreased in the whole vertebral body, while Tb.N. were only decreased in the middle third of the vertebral body. Accordingly, surface densities (S-V) in non-adults, and also specific surfaces (S/V) in adults were increased, suggesting increased bone resorption. Depending on the preparation technique used in the present study, resorption lacunae and characteristic unmineralized osteoid seams could be demonstrated. In conclusion, it might be useful to establish such techniques and standards for the diagnosis of disturbed mineralization in clinical patients. Copyright (C) 2003 John Wiley Sons, Ltd.

Osteonecrosis (ON) of the hip joint remains an unsolved therapeutical problem. Diagnosis of ON of the hip has been improved by the technical progress of imaging modalities and better understanding pathomorphology. Over a long period only plain radiographs have been available. Scintigraphy and computed tomography contributed to differential diagnosis and early detection of bone necrosis. Diagnosis in an early reversible stage is of importance. Understanding of pathophysiology, early diagnosis and therapeutical approach has been significantly improved by MR imaging. Using the ARCO system all imaging modalities and their diagnostic viability are described in the five ARCO stages. At the end a diagnostic algorithm will be proposed.

Niobium and tantalum in the annealed and cold-worked condition have been cycled at ultrasonic frequency at 90% of the fatigue limit at 2×108 cycles. Tantalum showed first cyclic softening followed by cyclic hardening after 105 cycles. Niobium showed cyclic softening only. Cyclic stress–strain behaviour of cold worked and annealed material showed similar trends.

We revised seven alumina-blasted cementless hip prostheses (Ti-alloy stems, cp Ti threaded sockets) with low- or high-carbon Co-alloy bearings at a mean of 20.1 months after implantation because of pain and loosening. Histological examination of the retrieved periprosthetic tissues from two cases in which the implant was stable and three in which the socket was loose showed macrophages with basophilic granules containing metal and alumina wear particles and lymph-cell infiltrates. In one of the two cases of stem loosening the thickened neocapsule also contained definite lymphatic follicles and gross lymphocyte/plasma-cell infiltrates. Spectrometric determination of the concentration of elements in periprosthetic tissues from six cases was compared with that of joint capsules from five control patients undergoing primary hip surgery. In the revisions the mean concentration of implant-relevant elements was 693.85 microg/g dry tissue. In addition to Cr (15.2%), Co (4.3%), and Ti (10.3%), Al was predominant (68.1%) and all concentrations were significantly higher (p < 0.001) than those in the control tissues. The annual rates of linear wear were calculated for six implants. The mean value was 11.1 microm (heads 6.25 microm, inserts 4.82 microm). SEM/EDXA showed numerous fine scratches and deep furrows containing alumina particles in loosened sockets, and stems showed contamination with adhering or impacted alumina particles of between 2 and 50 microm in size.

The influence of the loading frequency on the high cycle fatigue properties of two b.c.c. metals, commercially pure (c.p.) niobium and c.p. tantalum in annealed and cold worked condition, and of two annealed h.c.p. titanium and of Ti–6Al–7Nb alloy were investigated. Endurance data in the regime of 105 to 2×108 cycles to failure obtained with rotating bending and ultrasonic fatigue testing equipment (loading frequencies 100 Hz and 20 kHz, respectively) coincide within the ranges of scatter for niobium and Ti–6Al–7Nb alloy. The mean endurance limits at 2×108 cycles of these metals are ≈60% of the respective yield stress of the as produced material. The high loading frequency leads to prolonged lifetimes and increased mean endurance limits for tantalum and (less pronounced) for titanium. Fatigue crack initiation in tantalum changes from a preferentially ductile and transgranular mode at 100 Hz to a more brittle, crystallographic and intergranular mode at 20 kHz. The mean endurance limit of tantalum is above the yield stress of the as produced material, and high initial rates of plastic deformation therefore result. Cold working of tantalum and niobium improves their static strength properties, but is of only minor importance for the high cycle fatigue behaviour.

A newly developed implantable stimulator with 20 output channels, mainly intended for the stimulation of lower extremities in paraplegics, was implanted in 6 sheep over a time period of 26 weeks. Five epineural electrodes each were used to contact various nerves at different locations to elicit hip and knee extension and flexion and to make carrousel and selective stimulation possible. Different electrode application strategies in view of paraplegic standing and walking were investigated. Additional implanted electrodes allowed M-wave monitoring for selectivity investigations in 3 sheep. Stimulator, electrode leads, and electrodes proved to be reliable. Selective stimulation with electrodes placed on the trunk of the sciatic nerve could be demonstrated but with bad reproducibility. Histological investigation of the tissues surrounding electrodes and leads showed the expected stable foreign body response. Strong hip and knee extension could be gained in all cases while only weak flexion forces could be elicited in most cases. Muscle biopsies showed that daily stimulation for 8 h at threshold level caused an increase in muscle Type I fibers and a decrease in Type IIc fibers. Implants and electrodes fulfill the most important functional and biological criteria for their clinical application for paraplegic walking. The intention to provide selective flexion functions via epineural stimulation could not be demonstrated sufficiently in this animal model.

A model for critical limb ischemia was produced by occluding femoral vessels in 24 rabbits with a pneumatic cuff for 0, 2, 4, or 6 hours. Immediate sequelae and subsequent creeping substitution of cortical bone were observed in vivo using an implanted tibial window, the optical bone chamber implant (with intravital microscopy), and then by light and fluorescence microscopy of fluorochrome-labeled and surface-stained ground sections of retrieved implants. Six rabbits were used as controls (0 h) for each ischemia treatment, and the animals were monitored for 5 weeks postocclusion. A subpopulation of 13 implants was retrieved after euthanization and then histologically assessed for bone necrosis and remodeling. The hypothesis tested was that reperfusion injury during the 24 h after occluder release (reperfusion phase), and vessel perfusion/caliber, angiogenesis, and net bone resorption during the 5 subsequent weeks (creeping substitution phase), would exhibit ischemia duration-dependent effects. All animals could bear weight on the affected limb to ambulate by 1 week posttreatment. Two-way analysis of variance (ANOVA) comparison of the resulting data confirmed a significant difference between control and ischemia-treated rabbits for: (1) vessel perfusion/reperfusion; (2) vessel caliber; and (3) net bone resorption. Vascular responses to 4 vs. 6 h of ischemia were not significantly different, but net bone resorption was strictly ischemia duration-dependent. The conclusion that reperfusion injury was the mechanism spreading ischemia to more vessels was supported by a decrease in reperfusion and caliber of vessels, and an increase in vascular permeability and leukocyte adherence during the reperfusion phase. It is postulated that reperfusion injury produces a secondary ischemia that amplifies the occlusion-created primary ischemia and, in the present work, may have been succeeded by progressive episodes of ischemia, similar to the infarction pattern of ischemic hearts.

Different repair processes affect the clinical course of nontraumatic avascular femoral head osteonecrosis, not just necrotic lesion size and location. Fourteen femoral heads were retrieved at total hip arthroplasty after core decompression treatment, or after conservative treatment was done on 13 male patients diagnosed with different stages of femoral head osteonecrosis. To determine repair types, features of coronal magnetic resonance images were correlated with light microscopy findings on corresponding coronal undecalcified sections and microradiographs of the retrieved femoral heads.In five femoral heads, repair of necrotic bone and marrow remained restricted to the reactive interface for as many as 63 months, producing the diagnostic osteosclerotic rim with adjacent hypervascularity (limited repair). Nine femoral heads showed extension of the repair process into the necrosis. In five femoral heads, predominant resorption of necrotic bone led to femoral head breakdown within 2 to 50 months (destructive repair). In four femoral heads, reparative bone formation had started from subchondral fractures and/or the reactive interface, definitely reducing the size of the necrotic area (reconstructive repair). In the latter, the disease progressed slowly or stopped for as many as 45 months, irrespective of treatments, but elimination of risk factors seemed beneficial. Although core decompression did not always reach the necrotic area and improve repair, it reduced accompanying bone marrow edema and could delay the disease progress. Osteonecrosis with limited repair can be identified on magnetic resonance images obtained at followup, but the similar signal changes of destructive and reconstructive repair cannot be distinguished on magnetic resonance images alone. The evidence of reconstructive repair in nontraumatic osteonecrosis, however, gives hope for treatments that can improve repair to a sufficient creeping substitution of the affected femoral head.