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Osteolysis refers to an active resorption of bone matrix by osteoclasts during the natural formation of healthy bones. Osteolysis can be seen as the reverse of ossification. Osteolysis often occurs in the proximity of a prosthesis that either causes an immunological response or changes in the bone's structural load. Osteolysis may also be caused by pathologies like a bone tumor, cysts, or chronic inflammation.
Osteolysis in joint replacement
While bone resorption is commonly associated with many diseases or joint problems, the term osteolysis generally refers to a problem common to artificial joint replacements such as total hip replacements, total knee replacements and total shoulder replacements. Osteolysis can also be associated with the radiographic changes seen in a person with bisphosphonate-related osteonecrosis of the jaw.
There are several biological mechanisms which may lead to osteolysis. In total hip replacement the generally accepted explanation for osteolysis involves wear particles (worn off the contact surface of the artificial ball and socket joint). As the body attempts to clean up these wear particles (typically consisting of plastic or metal) it triggers an autoimmune reaction which causes resorption of living bone tissue. Osteolysis has been reported to occur as early as 12 months after implantation and is usually progressive. This may require a revision surgery (replacement of the prosthesis).
Although osteolysis itself is clinically asymptomatic, it can lead to implant loosening or bone breakage, which in turn cause serious medical problems.
Distal clavicular osteolysis
Distal clavicular osteolysis (DCO) is often associated with problems weightlifters have with their acromioclavicular joints due to high stresses put on the clavicle as it meets with the acromion. This condition is often referred to as "weight lifter's shoulder". US readily depicts resorption of the distal clavicle as irregular cortical erosions, whereas the acromion remains intact. Associated findings may include distended joint capsule, soft-tissue swelling, and joint instability.
A common surgery to treat recalcitrant DCO is re-sectioning of the distal clavicle, removing a few millimetres of bone from the very end of the bone.
- Sanjeev Agarwal (2004). "Osteolysis - basic science, incidence and diagnosis". Current Orthopaedics 18: 220–231. doi:10.1016/j.cuor.2004.03.002.
- Schwarzkopf R, Ishak C, Elman M, Gelber J, Strauss DN, Jazrawi LM (2008). "Distal clavicular osteolysis: a review of the literature". Bull NYU Hosp Jt Dis 66 (2): 94–101. PMID 18537776. [A Review of Weight-Lifter's Shoulder Lay summary] – eOrthopod.
- Arend CF. Ultrasound of the Shoulder. Master Medical Books, 2013. Sample chapter available at ShoulderUS.com
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