Sagittal claw (or hammer) deformity
What is claw-toe?
Claw-toe is a toe deformed by retraction, as if trying to claw the ground with the nail. The main cause is aging, but in some cases the cause is neurological or, more rarely, rheumatic, inflammatory or traumatic.
Footwear is not the cause of toe deformity, but claw-toe may be painless barefoot and painful in tight footwear, in which it rubs against the leather.
Claw-toe results from imbalance between the “extensor” (lengthening) and “flexor” (shortening) tendons and muscles, with the flexors taking over. The imbalance curls up the toe. At first, the deformity is reducible, as the tissues are still supple; but over time it becomes fixed due to retraction of the capsules, ligaments, tendons and finally skin.
Thus, the joints begin to protrude and rub against the footwear. The skin, to defend itself and resist, hardens into corns and calluses; this protects the area of friction, but can become painful. Such a hardened area on a toe is known as a “corn”.
Chiropody is then needed, to limit the thickness of the corn, and reduce pain. When this no longer suffices, we have to turn to surgery.
The various types of claw-toe
There are various types of claw-toe:
- Reducible (the deformity can be reduced manually), or irreducible: in time, the toe retracts and is no longer reducible; corns begin to appear.
- Claw-toe is said to be proximal or distal, depending on the position: either at the beginning of the toe (proximal) at the first joint, or at the end of the toe (distal) at the second joint (more precisely, “hammer-toe”).
There are some special cases:
- Hammer-toe: In hammer-toe, only the second joint is deformed. The deformity gives rise to a distal dorsal corn that may be isolated or associated with a pulp callus.
- Claw-toe associated with metatarsophalangeal joint dislocation results from either a metatarsal that is too long or, more often, impingement against a hallux valgus. This is known as second-ray syndrome. Second-toe claw is a typical decompensation following hallux valgus.
- 5th-toe claw is very frequent, typical, and troublesome for footwear.
Over time, the deformities worsen and become fixed. Footwear and walking become painful where the joints protrude. Repeated rubbing against footwear alters the skin, which protects itself by forming a corn or callus, just as happens on the hands of heavy manual workers. However, the volume of the corn aggravates the friction, making it yet more painful. In time, corns may become infected, leading to septic (infectious) arthritis.
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