Trigger finger: Location and association of comorbidities.
Trigger finger is a common cause of hand pain in the adult population. Studies in the past have suggested that ring finger and thumb are the most prevalent trigger fingers. Risk factors, such as diabetes and hypothyroidism, have been reportedly linked to trigger fingers. This observational prospective study was carried out to identify the most commonly affected trigger finger and observe associated comorbidities. At a single clinical site, a total of 46 patients with 54 trigger fingers on 49 hands were identified over a 7-week period. Ring finger, thumb, and long finger were observed to be the most frequent trigger fingers. No strong association between trigger finger and comorbidities, such as diabetes or hypothyroidism was observed.
One of the most common causes of hand pain in adults is trigger finger. In the general population, the reported prevalence of this condition is approximately 2%. (1) Although trigger fingers have been reported in all ages, the highest prevalence is found in the sixth and seventh decades of life, occurring six times as often in woman compared to men. (2) Numerous risk factors, including diabetes and hypothyroidism, have been identified as risk factors for the development of trigger finger. (2) It has been suggested that the ring finger and thumb are the most common trigger digits. (2) The goal of this study was to identify the most common trigger finger and observe the associated comorbidities.
Twenty-two extrinsic tendons cross the wrist and pass through a series of tight fibro-osseous canals that are designed to optimize the tendon's force production and efficiency of motion. (2,3) Fibro-osseous canals, made from the retinacular sheaths, form the flexor pulley system, which is comprised of five annular and three cruciform pulleys in each finger. The pulley system of the thumb is composed of two annular and one oblique pulley. (4) Of the five annular pulleys and the three cruciate pulleys for fingers and two annular and one oblique pulley for the thumb, the A1 pulley that lies over the volar surface of the metacarpal head is the pulley involved in trigger fingers. (3) The A1 pulley is subjected to the highest forces and pressure gradients due to its location during normal as well as power grip. (2)
The pathogenesis of trigger finger begins with inflammation of the flexor tendons and the tendon sheath. Inflammation of the tendon sheaths causes the sheath to hypertrophy. This thickening leads to the narrowing of the pulleys or the canals through which the tendons pass. (2,3) As a consequence of inflamed tendons and narrowed pulleys, the tendons do not glide through the pulley system smoothly and effectively, which is manifested in the form of pain, catching, locking, and clicking of the flexor tendon. This results in the classical clinical presentation of trigger fingers; pain and difficulty in achieving full extension of a single digit that eventually straightens or extends with snapping or popping.
A prospective observational study was conducted at a single clinic site. All patients who presented with symptoms consistent with a clinical diagnosis of trigger finger were included. Characteristics of their trigger finger, gender, hand dominance, age, and comorbidities were recorded. For patients with multiple trigger digits, each digit was identified as a separate digit.
Over a 7-week period, 46 consecutive patients with a total of 54 trigger fingers on 49 hands were identified. The mean age of the patient population was 67.2 years. Of the patients included in the study, 63% were females and 37% were males. A total of 67.3% patients presented with trigger finger in their dominant hand, and 32.7% patients had non-dominant hand trigger fingers (Table 1).
Of the 54 trigger finger, 19 (35.2%) were ring, 17 (31.5%) were thumb, 15 (27.8%) were long finger, and 3 (5.6%) were index finger. No little finger trigger finger was observed. Of the 46 affected patients, 18 (39.1%) had hypertension, 8 (17.4%) had hypothyroid, 8 (17.4%) had diabetes, 7 (15.2%) had high cholesterol, 2 (4.34%) patients had gout, and 2 (4.34%) patients had osteoarthritis. Thirteen (28.2%) patients had no identifiable comorbidities (Table 2).
The mean age of the patients with trigger finger was observed to be 67.2 years, which is consistent with the previously reported data of high prevalence of this condition in the sixth and seventh decades of life. (2) Similarly, the finding that 63% of the affected patients were females is also consistent with previous reports of the higher prevalence of trigger digits in the women. (2) Three patients were identified with trigger finger in both of their hands. As a result, trigger fingers were observed in 49 hands among 46 patients. Of the 49 hands affected, 33 (67.3%) were dominant, and 16 (32.7%) were non-dominant. Overuse of fingers and its association to triggering has not been well studied, and it is challenging to draw a strong conclusion as to why dominant hand trigger fingers are more common.
Of the 54 trigger digits, 19 (35.2%) were ring, 17 (31.5%) thumb, 15 (27.8%) long, 3 (5.6%) index, and 0 little. The ring finger was observed to be the most prevalent trigger finger, followed by the thumb, and then the long finger. Although not identical, the incidence of the ring finger, thumb, and long finger is quite similar. Together, these three digits accounted for almost 95% of the trigger digits. Little evidence exists as to why the incidence is much higher in these three fingers compared to the index or little. (2)
Hypertension was the most common comorbidity in this population, affecting 39.1% of the group. This is likely due to a high prevalence of hypertension in the age group studied. According to the 2011-2012 survey, 65% of the adults in the USA over the age of 60 have hypertension. (5) The next most common comorbidities were type II diabetes and hypothyroidism, at 17.4% of the study population each. According to a thyroid disease study done in Colorado, the prevalence of hypothyroidism in women of age 65 to 74 was 16% and in women older than 74 was 21%. (6) The same study found the prevalence in men of age 65 to 74 to be 11% and in men over the age of 74 to be 16%. This suggests that the observed incidence of hypothyroidism in this study population is similar to that of the background population. The same can be said for diabetes. According to the CDC report in 2014, 25.9% Americans over the age of 65 had diabetes (7); as only 17.4% of the patients in this study had diabetes, an association with triggering of the digits is unlikely.
Our observation that trigger finger has similar incidence in the ring, thumb, and long fingers coupled with low observed frequency of the suspected comorbidities, hypothyroidism and diabetes, does not support the previously indicated reports that the ring finger is the most common site of trigger finger, and the disorder is associated with diabetes and hypothyroidism. (2)
There are a few limitations to the study. The sample size of the study was small making it difficult to draw any conclusive evidence from the reported data. Additionally, the study was conducted at a single site in a major city, potentially limiting the generalizability of our findings. Past history of triggering was excluded.
This study suggests that trigger finger has a similar incidence in the ring, thumb, and long fingers. No strong association between trigger finger and diabetes or hypothyroidism was observed. The dominant hand is more likely affected by this condition, and women are at a greater risk of developing trigger digits than men. Larger future studies of the treatment of naive patients may help to further clarify the true distribution of this common condition.
None of the authors has a financial or proprietary interest in the subject matter or materials discussed in the manuscript, including, but not limited to, employment, consultancies, stock ownership, honoraria, and paid expert testimony
(1.) Moore JS. Flexor tendon entrapment of the digits (trigger finger and trigger thumb). J Occup Environ Med. 2000 May;42(5):526-45.
(2.) Makkouk AH, Oethen ME, Swigart CR, Dodds SD. Trigger finger: etiology, evaluation, and treatment. Curr Rev Musculoskelet Med. 2008 Jun;1(2):92-6.
(3.) Hotchkiss RN, Pederson WC, Wolfe WC, et al. Tenosynovitis. In: Green's Operative Hand Surgery. New York: Churchhill Livingston, 2005, pp. 2137-2158.
(4) Doyle JR, Blythe WF. Anatomy of the flexor tendon sheath and pulleys of the thumb. J Hand Surgery. 1997 Mar;2(2):1(4)9-51.
(5.) Nwankwo T, Yoon SS, Burt V, Gu Q. Hypertension among adults in the United States: National Health and Nutrition Examination Survey, 2011-2012. NCHS Data Brief. 2013 Oct;(133):1-8.
(6.) Canaris GJ, Manowitz NR, Mayor G, Ridgeway EC. The Colorado thyroid disease prevalence study. Arch Intern Med. 2000 Feb 28;160(4):526-34.
(7.) Center for Disease Control and Prevention. National Diabetes Statistics Report: Estimates of Diabetes and Its Burden in the United States, 2014. Atlanta, US Department of Health and Human Services, 2014, pp. 1-12.
Aadit Shah, B.S., and Michael Evan Rettig, M.D.
Aadit Shah, B.S., Albert Einstein College of Medicine, Bronx, New York. Michael Evan Rettig, M.D., Department of Orthopaedic Surgery, New York University Medical Center, Hospital for Joint Diseases, New York, New York.
Correspondence: Aadit Shah, B.S., 1925 Eastchester Road Apt 15E, Bronx, New York 10461; email@example.com.
Table 1 Demographics Mean Age 67.2 Gender Female 29 (63%) Male 17 (37%) Handedness Dominant 33 (67.3%) Non-dominant 16 (32.7%) Table 2 Location and Comorbidities Finger N (%) Comorbidities N (%) Ring 19 (35.2) Hypertension 18 (39.1) Hypothyroidism 8 (17.4) Thumb 17 (31.5) Diabetes 8 (17.4) High Cholesterol 7 (15.2) Long 15 (27.8) Gout 2 (4.3) Index 3 (5.6) Arthritis 2 (4.3) Little 0 None 13 (28.2)
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|Author:||Shah, Aadit; Rettig, Michael Evan|
|Publication:||Bulletin of the NYU Hospital for Joint Diseases|
|Article Type:||Clinical report|
|Date:||Jul 1, 2017|
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