Predictive value of bone mineral density and morphology determined by peripheral quantitative computed tomography for cancellous bone strength of the proximal femur.

Peripheral quantitative computed tomography (pQCT) is an established diagnostic method for assessment of bone mineral density in the diagnosis of osteoporosis. However, the capacity of structural parameters of cancellous bone measured by high-resolution computed tomography remains to be explored. In 33 patients, bone mineral density (BMD) of the proximal femur was measured in vitro by pQCT using cylindrical biopsies from the intertrochanteric region harvested before the implantation of an artificial hip joint. By digital image analysis of CT scans, parameters derived from histomorphometry describing the microarchitecture of cancellous bone were measured. The biopsies were also loaded to failure by an uniaxial compression test to determine the biomechanical parameters, Young's modulus, strength, and maximum energy absorption (E(max)). Strong correlations were found for BMD vs. mechanical parameters (r = 0.73 for Young's modulus, r = 0.82 for strength, and r = 0.79 for E(max); p < 0.001, n = 29). The morphological parameters, bone volume per trabecular volume (BV/TV), apparent trabecular thickness (app.Tb.Th), apparent trabecular separation (app.Tb.Sp), and trabecular number (Tb.N), correlated significantly with all mechanical parameters. The combination of morphological parameters with BMD in a multivariate regression model led to an overall, but only moderate, increase in R(2) in all cases. Our data confirm the high predictive value of BMD for the mechanical competence of cancellous bone of the intertrochanteric region. However, quantification of cancellous bone structure by image analysis of CT scans may provide additional qualitative information for the analysis of bone strength.

Correlation of bone mineral density with strength and microstructural parameters of cortical bone in vitro.

The aim of this study was to evaluate the influence of microstructural parameters, such as porosity and osteon dimensions, on strength. Therefore, the predictive value of bone mineral density (BMD) measured by quantitative computed tomography (QCT) for intracortical porosity and other microstructural parameters, as well as for strength of cortical bone biopsies, was investigated. Femoral cortical bone specimens from the middiaphysis of 23 patients were harvested during total hip replacement while drilling a hole (dia. 4.5 mm) for the relief of the intramedullary pressure. In vitro structural parameters assessed in histological sections as well as BMD determined by quantitative computed tomography were correlated with yield stress, and elastic modulus assessed by a compression test of the same specimens. Significant correlations were found between BMD and all mechanical parameters (elastic modulus: r = 0.69, p < 0.005; yield stress: r = 0.64, p < 0.005). Significant correlations between most structural parameters assessed by histology and yield stress were discovered. Structural parameters related to pore dimensions revealed higher correlation coefficients with yield stress (r = -0.69 for average pore diameter and r = -0.62 for fraction of porous structures, p < 0.005) than parameters related to osteons (r = 0.60 for osteon density and average osteonal area, p < 0.005), whereas elastic modulus was predicted equally well by both types of parameters. Significant correlations were found between BMD and parameters related to porous structures (r = 0.85 for porosity, 0.80 for average pore area, and r = 0.79 for average pore diameter in polynomial regression, p < 0.005). Histologically assessed porosity correlated significantly with parameters describing porous structures and haversian canal dimensions. Our results indicate a relevance of osteon density and fraction of osteonal structures for the mechanical parameters of cortical bone. We consider the measurement of BMD by quantitative computed tomography to be helpful for the estimation of bone strength as well as for the prediction of intracortical porosity and parameters related to porous structures of cortical bone.

Grading of tumors and tumorlike lesions of bone: evaluation by FDG PET.

UNLABELLED: Clinical diagnosis of skeletal tumors can be difficult, because such lesions compose a large, heterogeneous group of entities with different biologic behaviors. The aim of this prospective study was to assess the value of PET in grading tumors and tumorlike lesions of bone. METHODS: Two hundred two patients with suspected primary bone tumors were investigated using FDG PET. Uptake of FDG was evaluated semiquantitatively by determining the tumor-to-background ratio (T/B). All patients underwent biopsy, resulting in the histologic detection of 70 high-grade sarcomas, 21 low-grade sarcomas, 40 benign tumors, 47 tumorlike lesions, 6 osseous lymphomas, 6 plasmacytomas, and 12 metastases of an unknown primary tumor. RESULTS: All lesions, with the exception of 3 benign tumors, were detected by increased FDG uptake. Although sarcomas showed significantly higher T/Bs than did latent or active benign lesions (P < 0.001), aggressive benign lesions could not be distinguished from sarcomas. Using a T/B cutoff level for malignancy of 3.0, the sensitivity of FDG PET was 93.0%, the specificity was 66.7%, and the accuracy was 81.7%. CONCLUSION: FDG PET provides a promising tool for estimating the biologic activity of skeletal lesions, implicating consequences for the choice of surgical strategy.

Evaluation of neoadjuvant therapy response of osteogenic sarcoma using FDG PET.

UNLABELLED: According to the current treatment protocol of the Cooperative Osteosarcoma Study (COSS), monitoring preoperative chemotherapy response and estimating grade of tumor regression in patients with osteosarcoma is mandatory before surgical removal of the tumor, particularly if a limb salvage procedure is intended. In addition, response to neoadjuvant chemotherapy is considered as an important prognostic indicator. The aim of this prospective study was to assess the usefulness of 2-(18F) fluoro-2-deoxy-D-glucose (FDG) PET in the noninvasive evaluation of neoadjuvant chemotherapy response in osteosarcoma. METHODS: In 27 patients with osteosarcoma, we determined tumor-to-background ratios (TBRs) of FDG uptake with PET, before and after neoadjuvant chemotherapy according to COSS 86c or COSS 96 protocols, respectively. We compared changes in glucose metabolism of osteosarcomas with the histologic grade of regression in the resected specimen, according to Salzer-Kuntschik, discriminating responders (grades I-III; n = 17) and nonresponders (grades IV-VI; n = 10). RESULTS: The decrease of FDG uptake in osteosarcomas expressed as a ratio of posttherapeutic and pretherapeutic TBRs showed a close correlation to the amount of tumor necrosis induced by polychemotherapy (P < 0.001; Spearman). With a TBR ratio cutoff level of 0.6, all responders and 8 of 10 nonresponders could be identified by PET. In addition, lung metastases of osteosarcoma were detected with FDG PET in 4 patients. CONCLUSION: FDG PET provides a promising tool for noninvasive evaluation of neoadjuvant chemotherapy response in osteosarcoma. This could imply consequences for the choice of surgical strategy, because a limb salvage procedure cannot be recommended in patients nonresponsive to preoperative chemotherapy unless wide surgical margins can safely be achieved.

Prediction of strength of cortical bone in vitro by microcomputed tomography.

OBJECTIVE: The aim of this study was to evaluate the predictive value of bone mineral density and intracortical porosity measured by microcomputed tomography for the strength of cortical bone biopsies. DESIGN: Experimental study comparing the predictive value of bone mineral density and of intracortical porosity determined in vitro by microcomputed tomography for the mechanical properties of cortical bone cylinders. BACKGROUND: The assessment of cortical bone strength might be relevant for the prediction of fracture risk or the choice of suitable therapy strategies in orthopaedic surgery. The predictive value of cortical density for the mechanical properties is discussed controversially. The relevance of intracortical porosity measured by histomorphometry has been established, but the predictive value of porosity determined by microcomputed tomography remains to be explored. METHODS: Femoral cortical bone specimens from the mid diaphysis of 24 patients were harvested during total hip replacement procedure at the location, where a diaphyseal hole (diameter 4.5 mm) was drilled in order to reduce the intramedullary pressure. In vitro intracortical porosity and bone mineral density measurements by microcomputed tomography were compared with strength and elastic modulus assessed by a compression test transverse to the Haversian systems of the same specimens. RESULTS: Significant negative correlations were found between porosity measured by microcomputed tomography scans and yield stress, stiffness and elastic modulus (P<0.001), however, the positive correlations between bone mineral density and mechanical parameters were stronger (P<0.0001). The mechanical parameter best predicted by mineral density as well as by porosity was yield stress (r=0.72,P<0.0001;r=-0.64,P<0.001). CONCLUSIONS: Bone mineral density determined by microcomputed tomography imaging in vitro may be a potent method to predict mechanical properties of cortical bone non-destructively. The application in vivo remains to be explored.

Predictive value of Singh index and bone mineral density measured by quantitative computed tomography in determining the local cancellous bone quality of the proximal femur.

OBJECTIVE: The purpose of this study was to assess the predictive value of the Singh index as well as quantitative computed tomography for the in vitro local mechanical competence of the cancellous bone of the proximal femur. DESIGN: An experimental study examining the relation between mechanical properties and bone mineral density of the femoral neck determined in vitro and the clinical estimated Singh index on X-rays. BACKGROUND: Evaluation of the predictive value of the Singh index, an inexpensive and simple technique for the mechanical properties of the cancellous bone of the proximal femur. METHODS: The bone quality of the proximal femur of 34 patients undergoing total hip replacement was estimated by roentgenography using the Singh index. Bone mineral density was quantified by quantitative computed tomography using cylindrical cancellous bone biopsies harvested during the total hip replacement procedure by a new biopsy method. The mechanical properties of the bone specimens (Young's modulus, strength and maximum energy absorption E(max)) were measured by mechanical testing of the bone biopsies. RESULTS: A strong correlation of the Singh index versus material properties of cancellous bone was noted (r=0.66 for Young's modulus, r=0.73 for strength and r=0.69 for E(max), P<0.0001). The correlations of bone mineral density measured by quantitative computed tomography versus Young's modulus, strength and energy absorption E(max) were significant. Strength was predicted best (r=0.82; P<0.0001), followed by E(max) (r=0.79; P<0.0001) and Young's Modulus (r=0.73; P<0.0001). CONCLUSIONS: We conclude, that assessment of bone mineral density by quantitative computed tomography is a reliable and precise method for the estimation of cancellous bone material properties. The Singh index provides a rough estimate for the mechanical competence of the proximal femur. It is inexpensive, simply to assess and can in some cases replace the measurement of bone mineral density, notably in cases of marked decrease in bone density.

An unusual cause of upper gastrointestinal haemorrhage--perforation of a vena cava filter into the duodenum.

Penetration of vena cava inferior filter spikes through the vessel wall is a frequent but only rarely symptomatic complication of these devices. We report a case of upper gastrointestinal haemorrhage 11 year after implantation of a Mobin-Uddin filter. At gastroduodenoscopy a filter spike protruding from the duodenal mucosa was identified as the cause of the haemorrhage. After removal of the filter the patient made an uneventful recovery. Indications for vena cava filter placement are discussed in the light of their early and late complications. Surgical intervention is strongly recommended for symptomatic perforations.

[The Askin tumor]. / Der Askin-Tumor.

The Askin tumor, a primitive malignant small-cell tumor of the chest wall, is mostly seen among children and adolescents. It is closely related to Ewing's sarcoma of the same location, both tumors showing a chromosomal translocation t(11;22). Its origin from neuroectodermal cells is deducted from several ultrastructural details and from the expression of specific markers like NSE. Pain and deformation of the chest wall are the cardinal clinical signs of the tumor. Chest X-rays will frequently show destruction of ribs and pleural effusions. Effective therapy consists of radical surgery, local radiation and adjuvant chemotherapy. This multimodal concept allows minority of patients to remain disease-free but the overall outcome is rather unfortunate.

[Argon gas embolism in laparoscopic cholecystectomy with the Argon Beam One coagulator]. / Argongas-Embolie während laparoskopischer Cholecystektomie mit dem Argon-Beam-One-Coagulator.

The report is about argon embolism in a 37-year-old female patient during laparoscopic cholecystectomy and coagulation of a liver bed bleeding with the "Argon Beam One". The presented case report is to show that in spite of technical perfection and correct use of the Argon Beam One coagulator unfavorable anatomical conditions can cause life threatening gas embolism.

[Color Doppler controlled needle biopsy in diagnosis of soft tissue and bone tumors]. / Die farbdopplersonographisch gesteuerte Nadelbiopsie in der Diagnostik von Weichteil- und Knochentumoren.

In a prospective study we investigated 168 patients with musculoskeletal tumors, including 71 sarcomas, by core needle biopsy using the high-speed device Autovac. Monitoring with colour-coded duplex sonography allowed a well-aimed puncture of smaller or deeply localized lesions and also permitted the discrimination of necrotic and viable parts of the tumor. Adequate material for histologic diagnosis including grading and determination of tumor subtype was obtained from soft tissue sarcomas, soft tissue metastases, malignant lymphomas, plasmacytomas, and osteolytic skeletal secondaries. In contrast, in benign soft tissue and bone tumors the diagnosis could be established in only 66% of cases. Although skeletal sarcomas were identified as malignant mesenchymal lesions, a complete histologic classification of tumor subtype frequently was not possible due to an insufficient tissue specimen. With an accuracy of 97% for the diagnosis of malignancy and of 94% for the diagnosis of soft tissue sarcoma the results of core needle biopsies were comparable to those of incisional biopsies, the reference standard in the diagnosis of musculoskeletal tumors. Regarding the known disadvantages and the oncological risks of incisional biopsies, needle biopsy should replace the open procedure as the primary means of diagnosis in soft tissue and osteolytic bone tumors.

Injury classifications and operative approaches in hip dislocation and fractures.

During the last few decades, traumatic injuries of the hip joint have significantly increased in number, and traffic accidents have also increased. Depending on the speed, direction of the forces and the position of the femur at the moment of impact, different patterns of injury occur. Basically, they are classified as hip dislocations, dislocation fractures and acetabular fractures. These injuries have in common a high rate of concomitant lesions. Several classification systems have been developed for these injuries. Commonly, Stewart and Milford's or Levin's classification is used for dislocations and dislocation fractures. For acetabular fractures, Judet and Letournel's classification and its newer version developed by Helfet (AO classification) are generally accepted. Fractures of the femoral head, though included in these classifications, are typically described by separate classifications like the one presented in 1957 by Pipkin. The multitude of injuries occuring in the hip joint requires vast knowledge of various operative approaches. No single approach exists that would permit the treatment of all injuries in an ideal fashion. Approaches are either considered limited (Kocher-Langenbeck, ilioinguinal iliofemoral) when they permit access only to a restricted segment of the joint, or extended (extended iliofemoral, Maryland, Ruedi) when they allow all-around visualization of the hip joint. The choice of the best approach for an individual patient depends on the type of injury and also on patient variables like age, preexisting disease, and concomitant injuries. The decision is further influenced by the timing of surgery, the kind of fracture stabilization intended and by complications typically seen with certain approaches. The indication for extended procedures is only seen in patients with complex injury patterns involving both the anterior and the posterior column or in delayed cases undergoing surgery more than 3 weeks after trauma. Extended approaches permit excellent visualization of the fracture, but the extent of the soft tissue trauma is reflected in a high rate of postoperative complications. After a phase in which extended procedures were favored, recently a trend towards more limited approaches can be recognized because of their lower complication rate. This is facilitated by modern fracture-reduction methods using indirect techniques.

[Epiphyseal fracture of the proximal tibia: review of the literature and report of simultaneous bilateral fractures in a 13-year-old boy]. / Epiphysenfraktur der proximalen Tibia: Literaturübersicht und Fallbericht einer simultanen bilateralen Fraktur bei einem 13-jährigen Jungen.

Proximal tibial epiphyseal injury is a rare finding in adolescents. We report the case of a 13-year-old boy with simultaneous epiphyseal fractures of both proximal tibiae to illustrate appropriate diagnosis and treatment of this condition. The injury occurred while performing a long jump: a Salter-Harris type II fracture of the right proximal tibia was sustained at take-off and a Salter-Harris type III avulsion fracture of the left tibial tuberosity upon landing. Closed reduction and internal fixation using K-wires were performed on the right side, whereas open reduction and internal fixation were done on the left side, using a lag screw and additional McLaughlin wiring.

[Injury classification and surgical approach in hip dislocations and fractures]. / Verletzungsklassifikationen und operative Zugänge bei Hüftgelenkluxationen und -frakturen.

During the last few decades, traumatic injuries of the hip joint have significantly increased in number, and traffic accidents have also increased. Depending on the speed, direction of the forces and the position of the femur at the moment of impact, different patterns of injury occur. Basically, they are classified as hip dislocations, dislocation fractures and acetabular fractures. These injuries have in common a high rate of concomitant lesions. Several classification systems have been developed for these injuries. Commonly, Stewart and Milford's or Levin's classification is used for dislocations and dislocation fractures. For acetabular fractures, Judet and Letournel's classification and its newer version developed by Helfet (AO classification) are generally accepted. Fractures of the femoral head, though included in these classifications, are typically described by separate classifications like the one presented in 1957 by Pipkin. The multitude of injuries occurring in the hip joint requires vast knowledge of various operative approaches. No single approach exists that would permit the treatment of all injuries in an ideal fashion. Approaches are either considered limited (Kocher-Langenbeck, ilioinguinal iliofemoral) when they permit access only to a restricted segment of the joint, or extended (extended iliofemoral, Maryland, Ruedi) when they allow all-round visualization of the hip joint. The choice of the best approach for an individual patient depends on the type of injury and also on patient variables like age, preexisting disease, and concomitant injuries. The decision is further influenced by the timing of surgery, the kind of fracture stabilization intended and by complications typically seen with certain approaches. The indication for extended procedures is only seen in patients with complex injury patterns involving both the anterior and the posterior column or in delayed cases undergoing surgery more than 3 weeks after trauma. Extended approaches permit excellent visualization of the fracture, but the extent of the soft tissue trauma is reflected in a high rate of postoperative complications. After a phase in which extended procedures were favored, recently a trend towards more limited approaches can be recognized because of their lower complication rate. This is facilitated by modern fracture-reduction methods using indirect techniques.

[Can endoscopic methods decrease the mortality and complication rate of bleeding stomach and duodenal ulcer? A study of the literature]. / Kann durch endoskopische Methoden die Letalitäts- und Komplikationsrate des blutenden Ulcus ventriculi bzw. duodeni gesenkt werden? Eine Literaturstudie.

Bleedings from gastroduodenal ulcers still pose a major threat to health and life of a patient. Recent technical developments have provided the endoscopist with several methods for achieving hemostasis. In the present paper the results from clinical studies concerning interventional endoscopy shall be discussed. Criteria for the therapeutic approach for an individual patient shall be presented. Optimal results are possible if diagnosis and initial treatment are handled quickly by an experienced endoscopist. Early cooperation with the surgeon will further improve the outcome.

[Luxatio humeri erecta. A rare form of inferior shoulder dislocation]. / Die luxatio humeri erecta. Eine seltene Form der inferioren Schulterluxation.

In patients with erect dislocation of the shoulder, the arm is typically locked in an upright position. This rare variant of subglenoid luxation always causes damage to the ligamentous structures of the joint and sometimes additional complications arise from neurovascular lesions. Two recent cases are reported here. The mechanism of injury, therapeutic measures and prognosis are discussed.

[Obturator dislocation of the hip joint]. / Die Luxatio obturatoria des Hüftgelenkes.

Luxatio obturatoria may occur in the case of a trauma affecting the hip joint when the latter is in a position of flexion, abduction and external rotation. The femoral head dislocates anteriorly and caudally towards the foramen obturatum. A recent case will be presented with a discussion of the general aspects of this injury, with special emphasis on concomitant injuries and their significance of the long-term prognosis.

First histological observations on the incorporation of a novel calcium phosphate bone substitute material in human cancellous bone.

Calcium phosphates are frequently used as bone substitute materials because of their similarity to the mineral phase of bone, absence of antigenicity, and excellent osteoconductivity. However, in most currently available mineral substitutes, resorption occurs slowly if at all. In contrast, calcium phosphate cements have shown rapid resorption and remodeling in animal studies. In two prospective studies, a novel amorphous calcium phosphate cement (Biobon) was implanted in human patients for the first time. After 2-12 months, ten biopsies were obtained from nine individuals during secondary surgical interventions, for example, for implant removal. In all specimens, partial replacement of the material by new bone was observed, while residues of the cement were still visible. Undecalcified sections revealed extensive bone formation in immediate contact to the cement without fibrous interface. Polynucleated cells and superficial lacunae were indicative of resorptive activity, but inflammatory tissue response was absent. The new bone displayed regular trabecular and osteonal patterns. The histologic findings are in accordance with the excellent biocompatibility observed in the clinical follow-up. Though still incomplete, the resorbability of this cement appears superior to sintered calcium phosphates in these biopsy specimens. Presumably this is due to its amorphous crystalline structure. Biobon merits further studies as a promising substance for bone defect reconstruction in non-stress-bearing areas.

[Fractures of the upper extremity in the elderly]. / Frakturen der oberen Extremität beim alten Menschen.

PROBLEM: The primary goal in treating fractures in elderly persons is safe and rapid restoration of their functional capabilities to secure independence in everyday activities. The intention of this paper is to present an overview of treatment principles useful in this age group. METHODS: We analysed a series of 404 patients above the age of 70 years who underwent surgery for fractures of the arm between 1981 and 1997. RESULTS: Diaphyseal fractures are less frequent in this age group and their treatment does not differ significantly from principles established for younger patients. The majority of fractures of the proximal humerus and the distal radius can be treated by conservative means. Unstable fractures are frequent in the distal humerus and the olecranon requiring operative reduction and osteosynthesis. CONCLUSIONS: Preferred operative techniques in aged persons inflict minimal surgical trauma and have a low rate of complications and secondary interventions. In contrast, anatomical reconstruction has the highest priority in younger individuals.