Joint spacing

The spacing of both transverse and longitudinal joints is again left to the designer s experience in relation to the materials used and environmental conditions. As a general guide, it is 

Stated that the joint spacing (in feet) for unreinforced pavement should not greatly exceed twice the maximum slab thickness (in inches) . Additionally, the ratio of slab width to length should not exceed 1.25 (AASHTO 1993). According to the author s experience, the above guides are too loose to prevent the development of thermal cracking. 

As for the expansion joints, it is stated that the use of expansion joints is generally minimized on a project due to cost, complexity and performance problems . 

Finally, with regard to the longitudinal construction joints, it is simply stated that they should be placed at lane edges to maximize pavement smoothness and minimize load transfer problems (AASHTO 1993). 

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This relies on the integrity of the concrete construction itself with reference to design (crack control, joint spacing and detailing, concrete mix) and skilled workmanship and supervision. 

The transcellular fluid includes the viscous components of the peritoneum, pleural space, and pericardium, as well as the cerebrospinal fluid, joint space fluid, and the gastrointestinal (GI) digestive juices. Although the transcellular fluid normally accounts for about 1% of TBW, this amount can increase significantly during various illnesses favoring fluid collection in one of these spaces (e.g., pleural effusions or ascites in the peritoneum). The accumulation of fluid in the transcellular space is often referred to as third spacing. To review the calculations of the body fluid compartments in a representative patient, see Patient Encounter 1. 

Synovial fluid analysis Yellow, cloudy, decreased viscosity Hand x-rays Soft tissue swelling, joint space narrowing, no evidence of erosions... 

As the disease progresses, joint-space narrowing, subchondral bone sclerosis, and osteophytes may be detected. 

Radiology Radiography of the affected knee shows joint-space narrowing and subchondral bone sclerosis. 

O Gout results from deposition of uric acid crystals in joint spaces, leading to an inflammatory reaction that causes intense pain, erythema, and joint swelling. 

The solubility of uric acid depends on concentration and temperature. At high serum concentrations, lower body temperature causes the precipitation of monosodium urate crystals. Collections of these crystals (called micro tophi) can form in joint spaces in the distal extremities. 

I low incidence of side effects. Joint fluid obtained by arthro-centesis should be examined for evidence of joint-space infection and crystal identification. If no infection is present, intraarticular injection can proceed. 

Repeated use also may cause degradation of collagen.17 In fact, many patients diagnosed with chronic tendonitis may not have inflammation but instead have tendinosis, a condition marked by these collagen changes. Overuse of a joint also can result in an inflamed bursa. Since the bursa serves to reduce friction within the joint space, bursitis causes stiffness and pain. 

Substantial loss of cartilage causes joint space narrowing and leads to painful, deformed joints. The remaining cartilage softens and develops fibrillations,... 

Criteria for the classification of OA of the hips, knees, and hands were developed by the American College of Rheumatology (ACR). The criteria include the presence of pain, bony changes on examination, a normal erythrocyte sedimentation rate (ESR), and radiographs showing characteristic osteophytes or joint space narrowing. 

For hip OA, a patient must have hip pain and two of the following (1) an ESR less than 20 mm/hour, (2) radiographic femoral or acetabular osteophytes, or (3) radiographic joint space narrowing. 

Chronic inflammation of the synovial tissue lining the joint capsule results in tissue proliferation (pannus formation). Pannus invades cartilage and eventually the bone surface, producing erosions of bone and cartilage and leading to joint destruction. The end results may be loss of joint space, loss of joint motion, bony fusion (ankylosis), joint subluxation, tendon contractures, and chronic deformity. 

In addition to the phagocytic activity of the leukocytes, small peptide substances, such as the kinins, which are thought to be partially responsible for the local inflammatory response in gouty arthritis, accumulate in the joint space. The inflammation is associated with local vasodilation, increased vascular permeability, and pain. 

Certain drugs (i.e. glucocorticoids) can be administered directly into a joint space for the treatment of local condition i.e. rheumatoid arthritis. 

Methotrexate (Folex, Rheumatrex) is an antimetabolite used frequently in the treatment of cancer (see Chapter 36). There is considerable evidence that this drug is also one of the most effective DMARDs.15 76 Methotrexate has been shown to slow the effects of rheumatoid arthritis as evidenced by decreased synovitis, decreased bone erosion, and less narrowing of the joint space.37 The therapeutic effects of methotrexate have also been reported to be equal to, or better than, other DMARDs such as oral gold or azathioprine, and methotrexate may offer an advantage in terms of a rapid onset.68,90 Hence, methotrexate s popularity as a DMARD has increased during the past few years, and this drug is often the first DMARD used to treat rheumatoid arthritis in both adults and children.76... 

Figure 4.2 Joint space of vacation destinations and attributes...

The initial symptoms of rheumatoid arthritis are vague. They can include fatigue, malaise, joint pain, swelling of joints and stiffness. Patients will complain of joint pain and a loss of function in the affected joints. Radiographs may show erosion of the joint and a loss of joint space. 

Osteoarthritis is a chronic disease which is characterised by pain and stiffness in the joints. It is not simply a disease caused by wear and tear, many factors can be involved. There is a loss of cartilage and a loss of joint space. There may be bony overgrowths at joint margins. The joints most commonly affected are those of the hands, the knees, hips and spine. 

Inflammation is a spontaneous, physiological reaction which protects the host against hostile environments and which is focussed on protection from invasion of foreign organisms and mechanical injury. Inflammation is associated with a dramatic rise in the number of polymorphonuclear leukocytes (PMNs) and monocytes in the affected tissues (e.g. articular joint space during... 

The evidence for a pathophysiological role of oxidants in connective tissue injury is not confined to oxidative damage to the component macromolecules. Since there is reasonable indirect evidence that ROIs are released into the articular joint space during inflammation, it is likely that ROIs released from inflammatory cells which are adherent to or in contact with the articular cartilage surface might also damage the cellular components of articular cartilage. 

Synovial Fluid The compartment of a joint space in the rat knee is filled with the synovial fluid. It has been shown that a microdialysis probe with the 0.5 mm membrane can be used for kinetics and distribution studies of drugs such as bis(5-amidino-2-benzimidazolyl)methane in experimentally induced arthritis (St. Claire and Brouwer, 1992). 

During its operational lifespan the station provided a zero-gravity laboratory for mankind, and saw the dawn of tme international cooperation in planning joint space missions. Mir outlasted its ereators. Launched by the Soviet Union, it was deorbited by the Russian Federation space program. 

The change in disease state in OA is subjective. However, when X-rays have been used to measure changes in joint space, it cannot directly be linked to severity of pain that the patient is suffering, as it is not directly related to the disease as joint space width may not accurately reflect the width of articular cartilage. It would also be more helpful if the same outcome measures were used in each trial, as some use change in joint space whilst others use a questionnaire of symptom severity (e.g., WOMAC), or even both methods. " ... 

Acute attacks of gout are a result of urate crystal deposits in the synovium of joints. Crystal formation is dependent on a constellation of factors, including the degree of hyperuricemia, physical state of the joint, and presence of synovial fluid. Urate crystals present in the joint space can trigger an acute inflammatory response. Prostaglandins... 

Samarium-153 hydroxyapatite microspheres ( SmM) have been shown to ablate effectively normal and inflamed equine synovium, with minimal radiation hazard to the horse or medical personnel (Yarbrough et al 2000a,b). Within the joint space, the synovial lining primarily absorbs the energy from the Sm emissions, thus allowing the clinician to target the synovium for destruction. When m is combined with hydroxyapatite, exposure to other organs or support persormel is minimized. 

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