What is a snap finger?

A snap finger is an inflammation of the flexor tendons of the fingers or thumb. A knotty thickening impairs the sliding of the tendon. When the resistance is overcome, the finger or thumb is jerked into extension with more or less severe pain. In the vernacular, therefore, the designation of fast finger or thumb, snapping finger, jumping finger or trigger finger is common. This type of tendosynovitis is not caused by pathogens. The flexor tendons connect the fingertips to the muscles on the forearm. The tendons are guided through ring-shaped ligaments, like a fishing line through the rings of a fishing rod. The ligaments of the tendon sheaths can be differentiated according to their shape into ring ligaments and cruciate ligaments. In the case of a snap finger, the sliding obstacle occurs at the first ring ligament of the finger or thumb. This is where the technical term A1 ring ligament stenosis comes from. The inflammation and rubbing causes damage to the tendon. The severity of a snap finger is divided into four stages:

  • Grade I: A painful swelling in the palm can be palpated
  • Grade II: The finger snaps, but can still be stretched
  • Grade III: The finger can only be stretched with the help of the healthy hand
  • Grade IV: The finger can no longer be made completely straight

What are the symptoms of a snap finger?

Occasionally a touch sensitivity of the palm of the hand is noticed first. Closing the fist causes pain in the affected finger. If the hand is then opened again, a jerky extension of the finger occurs. The complaints develop over days to weeks. The snapping of the finger is most noticeable in the morning. The change from lying to standing and the movement of the fingers leads to a redistribution of the tissue water. Due to the decongestant swelling during the day, snapping improves. If the swelling of the tendon increases, the finger snaps permanently. Stretching the finger becomes more laborious and painful. If the jumping of the finger has been going on for months, a spontaneous improvement is unlikely. If the finger is not stretched for days because of the pain, the ligaments shorten and the middle joint stiffens. Not infrequently, similar complaints are felt on other fingers of the same or the other hand. Over 40 percent of those affected also suffer from carpal tunnel syndrome (Kumar P, et al., 2009, J Hand Surg Eur Vol). In this case, the fingers may feel numb, especially at night.

 

What are the causes of a snap finger?

Causes and triggers are often confused when talking about the development of carpal tunnel syndrome. The difference can be illustrated using the example of a heart attack. Physical exertion can trigger a heart attack, especially in people who suffer from lack of exercise. Sport helps to prevent a heart attack. In the case of a snap finger, the rapidity and pain are triggered by the movement of the fingers. The causes of the thickening of the tendons, however, are congenital. Changes in hormone metabolism favour the development of a snap finger. A lack of exercise and sudden unaccustomed strain in professional and private life can lead to injuries and diseases of the musculoskeletal system. On the other hand, regular physical exercise, whether as endurance training or strength training, leads to an adjustment of the body. Therefore, the tendon sheath of the fingers of sport climbers has been proven to be more resistant (Schreiber T, et al., 2015, Eur J Sport Sci). There are no reports about the frequent occurrence of fast fingers in sports climbers or concert pianists. For other tendosynovitis of the hand, such as tendovaginitis stenosans de Quervain, the assumption that it is caused by overloading has been refuted (Stahl S, et al., 2015, BMC Musculoskeletal Disord; Stahl S, et al., 2013, Plast Reconstr Surg).

 

How common is a snap finger?

The snap finger is one of the most common diseases of the hand. The probability of contracting a snap finger in the course of a lifetime is 2.6 percent. The incidence has been estimated at 28 new cases per 100,000 inhabitants (Strom L., 1977, Journal of the Medical Society of New Jersey). The incidence in the general population is about one percent (Shen PC, et al., 2019, Medicine (Baltimore)). Women are more frequently affected (1:4) (Fleisch SB, et al., 2007, J Am Acad Orthop Surg). Snap fingers occur most frequently in the fiftieth year of life. Most often the thumb, ring finger or middle finger is affected (Ragoowansi R., et al., 2005, Br J Plast Surg).

 

How is a snap finger detected?

The painful rapid movement is quite typical for a snap finger. Since the disease develops gradually, the exact beginning of the symptoms is often not remembered. During the examination, a swelling in the palm of the hand below the affected finger can be felt. A pressure at this point is usually painful. When moving the finger, the sliding of the thickened tendon can be felt. A snap can also be caused by an injury to the extensor tendon (extensor cap rupture, dislocation of an extensor tendon lateral tract). Rarely a snap can also be triggered by a malposition of the finger (gooseneck deformity). These injuries or malposition can be distinguished from a snap finger by examination by a hand surgeon.

 

What to do if I have a snap finger?

Many portals will be happy to provide you with information on how to cure or alleviate your symptoms. When it comes to your health, recommendations should be based on facts. Scientifically proven facts give you more certainty to make the right decision. The benefits of ointments, globules, bandages, ultrasound and electrotherapy as well as extracorporeal shock wave therapy are not certain with regard to the snap finger. Cold application, exercises and physiotherapy are of great importance after an operation. However, exercises alone can neither prevent nor heal a snap finger. An ergonomic working environment, for example with a palm rest and an ergonomic keyboard, is useful to support healing. Gentle treatment or a change of workplace cannot prevent or heal an inflammation of the tendon sheath.

 

What are the side effects of cortisone treatment of a snap finger?

The effectiveness of a cortisone injection has been well documented in numerous scientific studies (Peters-Veluthamaningal C, et al., 2009, Cochrane Database Syst Rev). The risks, benefits and alternative treatments should be carefully considered before any treatment. After a cortisone injection, a snap finger recurs in up to 48 percent of cases (Ring D., et al., 2008, J Hand Surg Am). Repeated injections of cortisone damage the tendons and suppress the body's own collagen production (Scutt N, et al., 2006, J Orthop.Res.). This can lead to tearing of the damaged tendon. The effectiveness of cortisone injections is reduced in recurrent or long-lasting springfing fingers. Treatment with a minor surgical procedure permanently eliminates snapping in nearly 100 percent of cases (Fiorini H.J., et al., 2018, Cochrane Database Syst Rev).

 

Snap fingers and snap thumbs for children and babies

Toddlers and babies can also suffer from a snap finger or snap thumb. Often parents report that their child cannot stretch a thumb. The congenital narrowing of the flexor tendon becomes noticeable between the first and fourth years of life. The thumb is by far the most frequently affected (Pollex flexus congenitus or rigidus). A snap finger occurs in less than three in every thousand newborns (Rodgers W. B., et al., 1994, J Hand Surg Am). Both sides can also be affected. During the examination, a nodular thickening of the flexor tendons in the metacarpophalangeal fold is felt. A snapping thumb can heal on its own even after several years. Scientific publications and hand surgical experience show that the bottleneck of the tendon can be quickly and reliably removed with a minor surgical procedure. The surgical treatment is characterized by very good results (Farr S, et al., 2014, J Hand Surg Eur Vol.). Since a short general anesthesia is required for infants, it is recommended to perform the surgery after the sixth month of life.

Which doctor treats a snap finger?

The treatment of diseases of the hand requires high professional competence and care. A three-year training course provides the necessary understanding of the complex interplay of tendons, nerves and joints in a very confined space. A hand surgeon specializes in the recognition, prevention and treatment of diseases of the hand. Microsurgical techniques are learned in the plastic surgeon training and in the additional training as hand surgeon. A plastic surgeon is particularly experienced in handling fine instruments. The mastery of tissue displacement techniques enables a plastic surgeon and hand surgeon to optimally treat even rare complications.

The operation for the treatment of the snap finger

The tendon can be released from its constriction with a 15-minute outpatient procedure under local anesthesia. Once the obstruction has been removed, the inflammation heals on its own. Before an operation, it is recommended to wash the hand carefully with soap. Long nails, varnished nails and artificial nails make disinfection more difficult and should therefore be avoided. Immediately before the operation, the skin is disinfected with an alcohol solution. The nerves of the palm of the hand are specifically anaesthetized with finest cannulas. Bloodless, optical magnification and microsurgical techniques help to preserve important structures and allow a better assessment of the tendons. The short skin incision of one to two centimeters is carefully planned by the hand surgeon. The constricting ligament is split. If necessary, adhesions are loosened, the tendon is smoothed and the damaged ligament or thickened sliding tissue is removed. The hand surgeon makes sure that the tendons slide freely during the operation. Of all treatment methods, surgery is the most effective method for permanent relief of symptoms (Amirfeyz R, et al, 2017, J Hand Surg (Eur Vol)). With appropriate follow-up care, a small, fine, inconspicuous scar remains.

Complications such as inflammation, restricted mobility or follow-up surgery are rare. Accompanying diseases such as diabetes, cigarette smoking, overweight and old age increase these risks. In general, the risk of movement restriction is 0.8 to 1.6 percent. The risk of inflammation is 0.5 to 0.6 percent (Werner BC, et al., 2016, J Hand Surg Eur Vol.). Other rare risks are a complex regional pain syndrome, a bowstring phenomenon and nerve injuries.

How can you prepare for a snap finger surgery?

  • All your questions about possible complications and alternative treatments should be answered in advance.
  • Limit nicotine and alcohol consumption to a minimum!
  • Surgery restricts the ability to travel by air. Therefore, do not plan to travel by air for business or private reasons in the 4 weeks after the operation!
  • Have ice cubes or cooling pads ready at home to cool the skin after the operation!

What do you have to consider after snap finger surgery?

  • It is very important to keep the hand elevated and cooled in the first 72 hours.
  • Complete fist closure and finger extension exercises should be performed several times per hour.
  • The skin sutures are removed after 10 to 14 days.
  • Postoperative clinical checks are recommended on the 3rd postoperative day and after 1 and 2 weeks.
  • Independent scar massage from the 3rd postoperative week onwards with moisturizing ointment (e.g. Bepanthen® Wound and Healing Ointment, Linola® Fat Cream) helps to create inconspicuous soft scars.

Author's statement

Author: Stéphane Stahl, MD, PhD. There are no financial relationships with the pharmaceutical or medical device industries that could have influenced the above text. Any reproduction, even partial, is permitted for personal use only. All texts used on this website are protected by copyright.

 

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