Border Gateway Protocol (BGP) is the protocol backing the core routing decisions on the Internet. It maintains a table of IP networks or 'prefixes' which designate network reachability among autonomous systems (AS). Point of concern in BGP is its lack of effective security measures which makes Internet vulnerable to different forms of attacks. Many solutions have been proposed till date to combat BGP security issues but not a single one is deployable in practical scenario. Any security proposal with optimal solution should offer adequate security functions, performance overhead and deployment cost. This paper critically analyzes the deployment issues of best three proposals considering trade-off between security functions and performance overhead.

Comparative analysis of

Background: the European Working Group on Sarcopenia in Older People has developed a clinical definition of sarcopenia based on low muscle mass and reduced muscle function (strength or performance). Grip strength is recommended as a good simple measure of muscle strength when ‘measured in standard conditions’. However, standard conditions remain to be defined. Methods: a literature search was conducted to review articles describing the measurement of grip strength listed in Medline, Web of Science and Cochrane Library databases up to 31 December 2009. Results: there is wide variability in the choice of equipment and protocol for measuring grip strength. The Jamar hand dynamometer is the most widely used instrument with established test–retest, inter-rater and intra-rater reliability. However, there is considerable variation in how it is used and studies often provide insufficient information on the protocol followed making comparisons difficult. There is evidence that variation in approach can affect the values recorded. Furthermore, reported summary measures of grip strength vary widely including maximum or mean value, from one, two or three attempts, with either hand or the dominant hand alone. Conclusions: there is considerable variation in current methods of assessing grip strength which makes comparison between studies difficult. A standardised method would enable more consistent measurement of grip strength and better assessment of sarcopenia. Our approach is described.

A review of the measurement of grip strength in clinical and epidemiological studies: towards a standardised approach

Open reduction and internal fixation is often required in comminuted, displaced intra-articular fractures of the distal radius when closed manipulation has failed to restore articular congruity. Results of surgical stabilization and articular reconstruction of these injuries are reviewed in this retrospective study of 49 patients with 52 displaced, intra-articular distal radius fractures. Forty-three patients with a mean age of 37 years (range, 17-79 years) were available for evaluation. The mean follow-up time was 38 months (range, 22-69 months). When rated by the system proposed by the Association for the Study of Internal Fixation (ASIF), 19 were ASIF type C2 and 21 were ASIF type C3. An injury score system based on the initial injury x-ray films was used to classify severely comminuted intra-articular fractures and to identify those associated with carpal injury. Postoperative fracture alignment, articular congruity, and radial length were significantly improved following surgery. Grip strength averaged 69 +/- 22% of the contralateral side, and range of motion averaged 75 +/- 18% of the contralateral side after surgery. A combined outcome rating system that included grip strength, range of motion, and pain relief averaged 76 +/- 19% of the contralateral side. Using regression analysis, a significant decrease was found in the combined rating with more severe fracture patterns as defined by the ASIF system, Malone classification, and the injury score system. The injury score system presented here and, in particular, the number of fracture fragments correlated most closely with the outcome of all classification systems examined. Operative treatment of complex distal radius fractures with reconstruction of articular congruity with internal fixation and/or external fixation can significantly improve functional outcome. The degree to which articular step-off, gap between fragments, and radial shortening are improved by surgery is strongly correlated with improved outcome, even when the results are corrected for severity of initial injury, whereas correction of radial tilt or dorsal tilt did not correlate with improved outcome.

Factors affecting functional outcome of displaced intra-articular distal radius fractures

System, including methods, apparatus, and kits, for retrograde placement of fasteners into bone.

Placement of fasteners into bone

A series of 166 perilunate dislocations and fracture-dislocations from 7 centers was retrospectively studied. The diagnosis was missed initially in 41 cases (25%). A classification system was presented. The perilunate fracture-dislocations were more frequent than the perilunate dislocations at a ratio of two to one. The displacement was dorsal in 161 cases (97%) and palmar in only 5 (3%). The dorsal transscaphoid perilunate fracture-dislocations represented 96% of the dorsal perilunate fracture-dislocations and 61% of the whole series. The clinical and radiologic outcome of 115 perilunate dislocations and fracture-dislocations with at least 1 year and an average of 6 years 3 months of follow-up was studied. Open injury and delay of treatment had an adverse effect on clinical results, whereas anatomical type had less influence. In cases treated early, the clinical results were satisfactory but the incidence of post-traumatic arthritis was high (56%). In the dorsal perilunate dislocation group of pure ligamentous injuries and in the dorsal transscaphoid group, the best radiologic results were observed after open reduction and internal fixation. In the latter group, the fixation of the scaphoid alone was not always sufficient and left occasionally scapholunate dissociation, lunotriquetral dissociation, ulnar translation of the carpus, or other carpal collapse patterns. The initial appraisal of both the osseous and ligamentous pathology was very important.

Perilunate dislocations and fracture-dislocations: A multicenter study

An experimental model using a static positioning frame, pressure-sensitive film (Fuji), and a microcomputer-based videodigitizing system was used to measure contact areas and pressures in the wrist. Contact areas and pressures were compared in a group of wrists between the normal state and with simulated distal radius fracture malunions of varying degrees. In simulated malunions, radial shortening to any degree slightly increased the total contact area in the lunate fossa, and was significant at 2 mm of shortening. By angulating the distal radius more than 20 degrees either palmar or dorsal, there was a dorsal shift in the scaphoid and lunate high pressure areas, and the loads were more concentrated, but there was no change in the load distribution between the scaphoid and lunate. Decreasing the radial inclination shifted the load distribution so that there was more load in the lunate fossa and less load in the scaphoid fossa.

Effects of distal radius fracture malunion on wrist joint mechanics

We dissected 393 wrists to evaluate the incidence and distribution of anatomic features, arthrosis, chondromalacia, and soft tissue lesions. The data were then analyzed for any statistically significant associations among the different variables. The most common (73%) lunate morphology had a separate medial facet on its distal surface for the hamate. The capitate had a separate facet for the fourth metacarpal in 86% of the wrists. Fourth metacarpals with a dorsal radial facet, either separate from or connected to the rest of the fourth metacarpal base, were the most common types of fourth metacarpal. Cartilage erosion with exposed subchondral bone was identified in 58% of the wrists. It was most commonly at the proximal pole of the hamate (28%). Tears of the ligaments and/or the triangular fibrocartilage complex were identified in 56% of the wrists. The triangular fibrocartilage complex was found torn in 36% of the wrists. The lunotriquetral interosseous ligament was torn in 36% of the wrists, and the scapholunate interosseous ligament was torn in 28% of the wrists. There was a communication between the proximal wrist joint and the pisotriquetral joint in 88% of the 76 wrists, which were further dissected to assess this issue. Statistical analysis of the data found a significant correlation between the presence of cartilage erosion at the proximal pole of the hamate and the presence of a lunate facet. There was also a significant correlation between the presence of a tear in the scapholunate interosseous ligament and the presence of cartilage erosion in the scaphoid-trapezium-trapezoid joint. Analysis of the paired wrists from 169 cadavers revealed that the same soft tissue tear or combination of tears was present bilaterally in 39% of the pairs. Cartilage erosion was present bilaterally in the same location or locations in 27% of the pairs.

Wrist anatomy: Incidence, distribution, and correlation of anatomic variations, tears, and arthrosis

The purpose of this study was to examine the anatomy and mechanical properties of the dorsal radiocarpal (DRC) and dorsal intercarpal (DIC) ligaments of the wrist and to better understand the functional design of the dorsal ligaments The DRC ligament was consistently found to originate from the dorsal margin of the distal radius and extended ulnar obliquely and distally Its radial fibers attached to the lunate and lunotriquetral interosseous ligament The DRC ligament then inserted onto the dorsal tubercle of the triquetrum The DIC ligament originated from the triquetrum and extended radially and attached onto the lunate, inserted into the dorsal groove of the scaphoid, and then extended to the trapezium The DRC and DIC ligaments together, in their lateral V configuration, act effectively as a dorsal radioscaphoid ligament that has the ability to vary its length by changing the angle between the 2 arms of the V The DRC-DIC ligaments' lateral V configuration allows normal carpal kinematics while maintaining its indirect dorsal stabilizing effect on the scaphoid throughout the range of motion of the wrist

The dorsal ligaments of the wrist: anatomy, mechanical properties, and function.

One hundred sixty-five cadaveric wrists were dissected to assess the incidence of a medial (hamate) facet on the lunate and any associated pathologic conditions. Forty-seven of these specimens and 137 clinical patients' radiographs were reviewed to attempt to recognize and further assess the incidence of a medial (hamate) facet on the lunate. Two types of lunate were identified. Type I, in which there was no medial facet, was evident in 34.5% of the dissected specimens and type H, in which there was a medial facet, was evident in 65.5% of the dissected specimens. The medial facets in the type II lunates ranged from a shallow 1 mm facet to a deep 6 mm facet. Significant cartilage erosion with exposed subchondral bone at the proximal pole of the hamate, which was not identifiable by radiograph, was evident at dissection in 44.4%) of the type II lunates, while none (0%) of the type I lunates had such associated hamate pathologic conditions. This type II lunate, with the high incidence of associated hamate pathology, may be an unidentified cause of wrist pain on the ulnar side.

Medial (hamate) facet of the lunate

Purpose: To compare the biomechanical properties of 6 dorsal and volar fracture fixation plate designs in a cadaver model. Method: Six different plating techniques were used on surgically simulated, unstable, extra-articular distal radius fractures in fresh-frozen cadavers. Specimens were tested to failure in axial compression with the Materials Testing System machine, and were analyzed with a motion analysis system. The 6 different fixation systems studied included an AO stainless steel Pi plate (group 1), an AO titanium Pi plate (group 2), a Forte plate (group 3), a dorsally placed Symmetry plate (group 4), a volarly placed Symmetry plate (group 5), and a volarly placed SCS/V plate (group 6). Results: All dorsal plates (groups 1, 2, 3, 4) failed in apex dorsal angulation and all volar plates (groups 5, 6) failed in apex volar angulation. No group developed an average angular deformity greater than 5° with a load of 100 N, which compares with the physiologic loads expected with active wrist motion. Only the volarly placed SCS/V plated specimens (group 6) resisted deformation of 5° or more at loads up to 250 N, which compares with the physiologic loads expected with active finger motion, and was significantly stronger and more rigid than the other 5 plate groups. Conclusions: The SCS/V plate fixation system is the most rigid of the systems tested and may offer adequate stability for the treatment of the distal radius fracture in which the anterior and/or posterior metaphyseal cortex is comminuted severely. (J Hand Surg 2003;28A:94-104. Copyright © 2003 by the American Society for Surgery of the Hand.)

Steven F. Viegas

Papers

Effects of distal radius fracture malunion on wrist joint mechanics

Wrist anatomy: Incidence, distribution, and correlation of anatomic variations, tears, and arthrosis

The dorsal ligaments of the wrist: anatomy, mechanical properties, and function.

Medial (hamate) facet of the lunate

Comparison of different distal radius dorsal and volar fracture fixation plates: a biomechanical study.