Doctors Lounge - Orthopedics Answers
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Forum Name: Bone trauma and fractures
Question: knee injury
|moomom - Thu Mar 31, 2005 10:29 pm||
several months ago, my husband fell on a piece of wood. it left a bruise and a vertical indention through the center of his knee. recently he has noticed something strange. there is a pea sized ball on the surface of the knee just under the skin. when you manipulate this 'pea' it moves freely around his knee. it doesn't hurt unless you apply alot of pressure. when he moves it around it looks weird. to feel it is strange also. any thoughts on what ths could be? should he go to the doctor? thanks
|Dr. A. Saif - Thu Apr 07, 2005 4:04 pm||
Hello again, Moomom,
Lots of causes for this mobile lump, after an injury. It could be "retention dermoid". This is an island of skin that gets embedded when there is an injury. It forms a tense lump, as the skin continues to shed squames (flakes of skin cells), but these squames are trapped buried undeer the surface. It is rare, and usually takes a few years to appear. It could be a bit of foreign matter trapped under the skin, embedded during the injury. This is perhaps more likely. It could be a feck of boneor osteophyte that was chipped off during the injury, and that has failed to get reattached. This is more likely within a joint, as there is space for the fragment to move around. In front of the knee however, it is conceivable that the fragment is now freely mobile within the "prepatellar bursa", a bag of fluid in front of the knee. Loose bodies can also develop spontaneously I gues, but rarely in the prepatellar bursa.
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