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In the medical community, ringbone is termed phalangeal exostosis. Simply put, it’s new bone growth on the proximal, middle or distal phalanx. This growth usually forms on the dorsal, dorsolateral and/or dorsomedial surfaces of the first and second phalanges and the extensor process of the third phalanx.
Unfortunately, ringbone may result in osteoarthritis or ankylosis (immobilization) of the pastern (proximal interphalangeal) or coffin (distal interphalangeal) joints.
Ringbone can be classified into four categories by the location of the new bone growth:
New bone growth occurs on the distal end of the first phalanx or the proximal end of the second phalanx (Figure 1). Clinically, there will be a bulging of the tissues approximately 1 inch above the coronary band.
New bone growth occurs on the distal end of the second phalanx and the proximal end of the third phalanx (Figure 2). Radiographically, this may be especially prominent at the extensor process of the distal phalanx.
FIGURE 1 - High Ringbone
New bone growth occurs around the joint capsule, but doesn’t involve the joint surface itself (Figure 3).
New bone growth involves the joint surface of the pastern or coffin joints (Figure 4). In this classification, the new bone growth is also accompanied radiographically by osteophytes (outgrowths) depicting degenerative joint disease.
Ringbone is often described with a combination of these classification terminologies. Examples of these descriptive terms include articular high ringbone, periarticular high ringbone, articular low ringbone and periarticular low ringbone.