Synovial joints, total

The major factors limiting the effective life of a total replacement synovial joint are loosening of one or more of the prosthetic components, a variety of medical problems (e g. infection) and wear. Most internal prostheses now consist of metallic and polymeric components and it is the penetration of the former into the latter which is the subject of this paper. 

The development of satisfactory total replacement synovial joints is sometimes described as the major advance in orthopaedic surgery in recent times. The hip joint was the first major load bearing joint to respond to the efforts of surgeons, engineers and materials scientists in the past two decades to develop satisfactory replacements, but attention is now focussed upon the more complex knee joint. 

It is important to recognize that friction and wear depend upon four major factors, that is, materials, design, operating conditions, and total environment (Figure 50.2). This four-block figure maybe useful as a guide in thinking about synovial joint lubrication either from a theoretical or experimental viewpoint—... 

Hyaluronan was identified by Karl Meyer11 in 1938 as a hexuronic acid-containing material that also provided the turgor for the vitreous of the eye. The name hyaluronic acid was proposed from the Greek hyalos (glassy, vitreous) and uronic acid. It required 20 years however before the chemical structure of HA was established.12 It was later found to be a present in virtually every vertebrate tissue, the highest concentrations occurring in the vitreous of the eye, in the synovial fluid in the joint capsule, and in the umbilical cord as Wharton s jelly. However, over 50% of total body HA is present in skin.13... 

Recently, we carried out immunohistochemical studies using an antibody directed against oLDL to demonstrate the presence of foam cells and fatty streaks around blood vessels within the sub-intimal lining of rheumatoid synovial tissue [125]. We have also found that the concentration of vitamin E is markedly diminished in synovial fluid from inflamed joints when compared to matched plasma samples, even after correcting for total lipid concentrations [126],... 

Goldring, S.R., SchiUer, A.L., Roelbe, M. et al., 1983. The synovial-like membrane at the bone-cement interface in loose total hip replacements and its proposed role in bone lysis. J. Bone Joint Surg. 65A 575. 

Lamovec, J., Zidar, A., Cucek-Plenicar, M. et al. (1988) Synovial sarcoma associated with total hip replacement. A case report. Addendum Osteosarcoma associated with a Charnley-Muller hip arthroplasty. J. Bone Joint Surg. 70A, 1558-1560. 

The use of crosslinked polyethylene in knee replacements is still relatively new and there are few studies into the wear occnrring in vivo. Iwakiri et al. (2009) measured the number of wear particles contained in synovial fluid removed from the knee joint of patients with a total knee replacement the implants in each patient were the same design, bnt the bearing surface in four knees had a crosslinked polyethylene insert, whereas three knees had an insert made from conventional UHMWPE. The number of wear particles was less for the crosslinked polyethylene insert (0.28 x 10 ) compared with the conventional UHMWPE insert (6.87 x 10 ). Rohrl et al. (2007) measured the penetration of the femoral head into acetabular sockets manufactured... 

It has been suggested that the constituents of the klnln system in synovial fluid of polyarthritic joints are mainly derived from plasma and not from invading leucocytes. Rheumatoid arthritic joints show higher protein concentrations than normal. Further, hyaluronic acid becomes more dilute and more abundant due to an increase in the amount of synovial fluid. Higher than normal levels of serotonin in the blood of arthritic patients have been demonstrated. Total hemolytic complement activities... 

Ragan and Meyer (354) have recently reported hyaluronic acid contents and relative viscosities of synovial fluids from the knee joints of 35 patients with rheumatoid arthritis and 11 patients without joint diseases. They found with very few exceptions that the apparent degree of polymerization of the hyaluronic acid was lower in the arthritic patients, although the total amount of the mucopolysaccharide present was greater. Hyaluronidase was not detected in joint fluid or in synovial or periarticular tissue and, in any event, its presence would not explain the increase in total hyaluronic acid. Therefore, it was concluded that the defect lies not in an enzymatic hydrolysis or nonspecific depolymerization but in abnormal synthesis of this polysaccharide, involving an increased production of incompletely polymerized hyaluronic acid. 

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