Trigger toe is a toe deformity affecting the big toe, which causes the toe to adopt a hooked or trigger shape. The cause of trigger toe and the method of its formation can be due to two distinct problems. The first is a problem with the flexor tendon responsible for moving the toe, called the flexor hallucis longus muscle and its associated tendon. The second is essentially the same condition as a hammer or mallet toe, with the difference being the location.
The flexor hallucis longus muscle starts in the lower leg in the posterior compartment, and runs from deep in the leg and where it attached to the last phalanx of the toe (the end toe bone) on the underside of the toe via its tendon. Trigger toe occurs when there is irritation of this tendon, with nodules forming which restrict its movement through the tendon sheath, or a tunnel through which the tendon passes. With the tendon movement restricted it can catch keeping the toe in a contracted curved state. The condition is more commonly seen in the fingers, where it is known as trigger finger although can affect the big toe. It is typified by a progressive restriction of the tendon sheath termed stenosing tenosynovitis.
Trigger toe has been most frequently reported in female ballet dancers, due to damage to the flexor hallucis longus tendon, and resultant swelling. The condition results in a difficulty or even impossibility of standing on tip toes which is a considerable problem for ballet dancers making it impossible to stand en pointe. Aside from the visual contraction of the toe and its bent appearance there may be some crepitation (cracking noise) from the affected toe when flexing and extending.
A sufferer of trigger toe is likely to experience a locking of the toe in its curled state, making it difficult to straighten, although the toe can suddenly snap up to its extended position as the node or nodule passed through the tendon sheath. The trigger toe sufferer may well have a similar problem with contracting the toe, with the problem happening in reverse.
The cause of trigger toe is often unclear, although it has been suggested that it can occur due to a forceful repetitive action of the toe, as is likely with ballet dangers, football kickers and top sportsmen and women.
The occurrence of trigger toe is so low that doctors may not initially diagnose the problem. Since the problem affects the tendon and not a bone, it will not show up on an x-ray, and may escape diagnosis through the normal range of tests. An MRI remains the best way to diagnose the problem, but due to the expense of this imaging test it is rarely covered by standard medical plan however even this imaging test may not be sufficient to diagnose the problem.
As with trigger finger, treatment would usually be an injection of corticosteroids to reduce inflammation and swelling to allow the normal passage of the tendon through the tendon sheath. The next step should the corticosteroid injection prove to be ineffective would be toe surgery to remove any node (if present), and/or the cutting of the tendon sheath.
Trigger toe is also the name sometimes given to a hammer toe condition affecting the big toe, whereby the ligaments and tendons have shortened keeping the toe in a contracted and bent state. This form of trigger toe is believed to be caused by highly restrictive footwear causing the toe to become bent when wearing shoes, such as those which are too small. The condition starts with the toe remaining flexible, but as the ligaments and tendons tighten the toe becomes more rigid and cannot be straightened. This form of trigger toe has been linked to tendon and ligament imbalances, neuromuscular disorders, high arches feet and diabetes. Easing of the pressure on the toe is sufficient to cure the problem in the early stages along with stretching exercises, although surgery may be called for to straighten the big toe if allowed to progress.