Textbook chapter: loose bodies tips and pearls

Intra-articular loose bodies have been known as a source of articular pain for many years. During the nineteenth century, loose bodies were believed to form either as a result of trau matic breakage of the articular cartilage or from the synovial membrane [ 1 ]. However, removal of loose bodies at that time could have been fatal [ 1 ]. Today, there are many indications for hip arthroscopy, with loose bodies as one of the most common [ 2 - 4 ]. Moreover, hip arthroscopy is ideally set for the removal of loose bodies [ 2 , 5 ]

In 1977, Milgram published a study on more than 300 dif - ferent specimens in which one or more osteochondral bodies were found in surgery; he has classified loose bodies into three groups [ 6 ]. The first group included patients with post - traumatic osteochondral fractures, in which articular carti - lage was found within the loose bodies, and in some cases, the concomitant chondral defect from which the loose body arose was found. The second class of loose body included those found in the presence of articular surface disintegration with degenerative joint disease and avascular necrosis (AVN); in these cases, articular surface damage was either noted in surgery or radiographically. The last group consisted of patients with myriads of free lose bodies, sometimes hun - dreds, and a grossly normal joint surface; these cases were presumed to be synovial chondromatosis. In addition to these classifications, Milgram also distinguished between loose bodies and attached osteochondral bodies. Nowadays, the nineteenth century theory is still valid; loose bodies can arise from tissue within the joint, the synovial membrane, or the articular surface. Once a loose body is lodged in the joint, a common sequence occurs: proliferation of bone and cartilage with subsequent resorption by osteoclasts on the surface [ 7 ]