Among the many explanations offered are the following:
- Dry arthritis, with overgrowth of the margins of the cartilages;
- Bony growths, separation from their attachments;
- Infarct of the articular cartilage, with final separation;
- Plate of bone formed outside of the joint and then invaginated;
- Calcification or chondrification of enlarged synovial fringes;
- Irritation and growth of embryonal cartilage or bone cells in the synovial fringes;
- Concretions whose nuclei are clots, torn fringes, or some foreign body;
- Some portion of the articular cartilages broken off by injury, or damage and subsequent separation.
Injury figures largely in the opinion of most of the authorities, it being well established that an injured portion of articular surface may become subsequently detached by a fatty necrosis, spoken of by König as osteochondritis dissecans, or by Paget as “quiet necrosis.” Others imagine that these floating bodies are rarely of traumatic origin.
Symptoms are usually marked and significant. There is sudden sharp and shooting pain, sometimes so severe as to cause faintness. Along with this there is “locking” i. e., fixation of the joint, usually in the flexed position, probably due to the entanglement of the floating body between the articular surfaces or between the bone and the capsule.
Fig. 210
Ankylosis of hip with contracture of knee, following post-scarlatinal arthritis.
It is the smaller rather than the larger bodies which give the most acute symptoms. This “locking” may last for only a few moments or for a number of hours and may or may not be followed by acute effusion. When with the above symptoms the presence in the joint of a movable mass can be made out diagnosis is complete. Some patients discover the movable body in their own joints before they go to the surgeon.
When the diagnosis is established the removal of the offending material is imperative. In the pre-antiseptic era this was an extremely hazardous operation. It is now one involving only theoretical risks. These bodies are sometimes extremely movable and slip about within the joint in a manner to almost defy removal even after the joint cavity is open. If such a body can be felt and fixed by digital pressure, or by the method of “stockading” suggested by Andrews some years ago, i. e., fixation by forcing sterilized pins into the tissues around it so that it cannot escape, it is then an easy matter to cut down upon it and remove it. Otherwise incision may require to be sufficiently ample to permit insertion of a finger and the general exploration of the joint before it is encountered. These bodies sometimes exist in small numbers, and it may be possible to remove several through a single opening. If the joint be opened and explored it should be done thoroughly in order that nothing may escape. After removal the capsule is closed with buried sutures, the balance of the wound closed as usual, and the limb then dressed upon a splint with absolute fixation for several days, in order to ensure physiological rest ([Fig. 209]).