Great Toe - Cartilage Damage

Articular cartilage is a thin, whitish, glistening layer of protective tissue that covers the joint surfaces of bones. Articular cartilage is composed of hyaline cartilage cells, which have many unique properties that allow it to function effectively as a smooth and lubricious load-bearing surface. Small defects in the articular surface can cause pain and restrict range of motion. When traumatized or injured, new hyaline cartilage cells do not replace damaged hyaline cartilage cells. Several joint diseases (e.g. rheumatoid arthritis) are complex inflammatory disease processes that slowly deteriorate the overall joint surface and often affect multiple joints at the same time. Arthrosurface's technology is not intended to treat these systemic joint diseases.

A different type of joint disease is the result of injury to a relatively small, localized area of the articular surface. These injuries create defects in the articular surface. These injuries or defects can be caused by either acute or repetitive trauma, as when one bony surface strikes against the opposing bony surface. The trauma may have occurred from athletics, a fall, car crash or other high-energy event or impact. These defects may also be caused by chronic conditions that cause the joints to load disproportionately on one side or area. These joint surfaces appear largely normal but have one or more localized lesions or defects. These defects range from a softening of the articular cartilage to complete loss of articular cartilage thus exposing the underlying bone.

The most common site of arthritis in the foot is at the base of the big toe. This joint is called the metatarso-phalangeal, or MTP joint. It's important because it has to bend every time you take a step. If the joint starts to stiffen, walking can become painful and difficult.

In the MTP joint, as in any joint, the ends of the bones are covered by a smooth articular cartilage. If wear-and-tear or injury damage the articular cartilage, the raw bone ends can rub together. A bone spur, or osteophyte, may develop on the top of the bone. This overgrowth can prevent the toe from bending as much as it needs to when you walk. The result is a stiff big toe, or Hallux Rigidus (also referred to as Hallux Limitus).

Hallux Rigidus/Limitus usually develops in adults between the ages of 30 and 60 years. No one knows why it appears in some people and not others. It may result from an injury to the toe that damages the articular cartilage or from differences in foot anatomy that increase stress on the joint. (Portions of this text reprinted from the AAOS)