Ultrasonographic assessment of clinically diagnosed trigger fingers

Tenosynovitis of hand: Causes and complications

Tenosynovitis represents a common clinical condition characterized by inflammation of the synovium that encases the tendon sheath. Although tenosynovities may be noted in any tendon in the body, extremities such as hand, and foot remain the sites of high predilection to acquire this condition. The predominant cause of this predilection rests in the intricate tendon arrangements in these extremities that permit fine motor actions. This editorial explores the common causes and the complications associated with this condition to improve the understanding of the readers of this common condition encountered in our everyday clinical practice.

Finger flexor rigidity in the healthy population

The involvement of the hand flexors in trigger finger is not clear. This study aimed to examine the rigidity of the flexor tendon in the first pulley territory in the hand by using ultrasound in a healthy population, as well as to create a reference scale of rigidity for the flexor tendons to compare those values in trigger fingers. We tested 35 healthy volunteers using a linear ultrasound transducer and the color Doppler method. Rigidity levels below the first pulley were examined and compared between the different fingers of the hand and the relationship between rigidity and sex and the three different age groups was evaluated. In the healthy population, the rigidity of the flexor tendons of the hand in the territory of the first pulley varied between 233.1 and 962.8 kPa, with an average of 486.42 kPa and standard deviation of 114.85. We showed that the flexors in the dominant hand were more rigid, there was a difference between the rigidity of the flexor tendons of the thumb and the other fingers of the same hand, and the ring finger of the dominant hand had stiffer flexor tendons than the fingers of the other hand in the male population. We created a value scale for the rigidity of the flexor tendons of the fingers. This base scale can be compared between different pathologies, including trigger finger. The study and all experimental protocols were approved by the local ethical committee.

The cross-sectional area ratio of a specific part of the flexor pollicis longus tendon- a stable sonographic measurement for trigger thumb: a cross-sectional trial

BACKGROUND

Trigger thumb is a pathologic condition of the digital pulleys and flexor tendons. To find a cutoff value of the cross-sectional area ratio of specific parts of the flexor pollicis longus tendon to diagnosis trigger thumb in the high-frequency ultrasound examination.

METHODS

We evaluated 271 healthy volunteers and 57 patients with clinical diagnosis of trigger thumb. The cross-sectional area of the metacarpophalangeal joint of flexor pollicis longus tendon (C1) and the cross-sectional area of the midpoint of the first metacarpal of flexor pollicis longus tendon (C2) were analyzed.

RESULTS

There is no difference between gender, age and left and right hands in the ratio of C1 to C2 (C1/ C2). The mean of C1/ C2 in the healthy thumb was 0.983 ± 0.103, which was significantly smaller in comparison to the diseased thumb (P < 0.05). Based on the receiver operating characteristic curve, we chose the diagnostic cut-off value for the C1/ C2 to be 1.362 and 1.153 in order to differ a trigger thumb from children and adults.

CONCLUSIONS

The C1/ C2 of the healthy thumb was relatively stable, with a mean value of 0.983 ± 0.103. The cutoff value of C1/C2 to distinguish healthy thumb from diseased thumb in children and adults were 1.362 and 1.153, respectively.

Mucopolysaccharidosis: What Pediatric Rheumatologists and Orthopedics Need to Know

Mucopolysaccharidosis (MPS) is a group of disorders caused by the reduced or absent activity of enzymes involved in the glycosaminoglycans (GAGs) degradation; the consequence is the progressive accumulation of the substrate (dermatan, heparan, keratan or chondroitin sulfate) in the lysosomes of cells belonging to several tissues. The rarity, the broad spectrum of manifestations, the lack of strict genotype-phenotype association, and the progressive nature of MPS make diagnosing this group of conditions challenging. Musculoskeletal involvement represents a common and prominent feature of MPS. Joint and bone abnormalities might be the main clue for diagnosing MPS, especially in attenuated phenotypes; therefore, it is essential to increase the awareness of these conditions among the pediatric rheumatology and orthopedic communities since early diagnosis and treatment are crucial to reduce the disease burden of these patients. Nowadays, enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT) are available for some MPS types. We describe the musculoskeletal characteristics of MPS patients through a literature review of MPS cases misdiagnosed as having rheumatologic or orthopedic conditions.

High HbA1c Levels Are Associated With Development of Trigger Finger in Type 1 and Type 2 Diabetes: An Observational Register-Based Study From Sweden

OBJECTIVE

Trigger finger (TF) is a hand disorder causing the fingers to painfully lock in flexion. Diabetes is a known risk factor; however, whether strict glycemic control effectively lowers risk of TF is unknown. Our aim was to examine whether high HbA1c was associated with increased risk of TF among individuals with diabetes.

RESEARCH DESIGN AND METHODS

The Swedish National Diabetes Register (NDR) was cross-linked with the health care register of the Region of Skåne in southern Sweden. In total, 9,682 individuals with type 1 diabetes (T1D) and 85,755 individuals with type 2 diabetes (T2D) aged ≥18 years were included from 2004 to 2019. Associations between HbA1c and TF were calculated with sex-stratified, multivariate logistic regression models with 95% CIs, with adjustment for age, duration of diabetes, BMI, and systolic blood pressure.

RESULTS

In total, 486 women and 271 men with T1D and 1,143 women and 1,009 men with T2D were diagnosed with TF. Increased levels of HbA1c were associated with TF among individuals with T1D (women OR 1.26 [95% CI 1.1-1.4], P = 0.001, and men 1.4 [1.2-1.7], P < 0.001) and T2D (women 1.14 [95% CI 1.2-1.2], P < 0.001, and men 1.12 [95% CI 1.0-1.2], P = 0.003).

CONCLUSIONS

Hyperglycemia increases the risk of developing TF among individuals with T1D and T2D. Optimal treatment of diabetes seems to be of importance for prevention of diabetic hand complications such as TF.

Trigger Finger From Ocean Rowing: An Observational Study

Background: Trigger finger has a prevalence of 2% to 3% in the general population. Although anecdotal evidence exists, there is a lack of conclusive data that prove a relationship between repetitive power grip and flexion with triggering. Ocean rowing is becoming a popular sport, with the race across the Atlantic alone attracting more than 100 participants annually. Anecdotal reports suggest ocean rowing may be a significant cause of trigger finger. We aimed to identify whether the sport causes an increased prevalence of triggering, whether there were any alleviating or compounding factors, and, finally, whether there was any effect on performance. Methods: A prospective observational study was carried out. A questionnaire was sent to all participants of the Talisker Whisky Atlantic Challenge 2018, which included a trigger finger self-scoring system and the Oslo Sports Trauma Center Overuse Injury Questionnaire. Results: Responses were received from 67 rowers (83% response rate). Age ranged from 21 to 62 years, with a mean of 40 years. In all, 49.3% had clinical triggering, with 79.3% reporting bilateral symptoms. The length of continuous rest time had a significant impact on the incidence of finger triggering and disease stage (P = .0275 and .0353, respectively; multivariate logistic regression). High-grade triggering had a more negative effect on rowing performance than low grade or no triggering (not significant). Conclusion: Ocean rowers suffered a 15-fold increase in trigger finger prevalence compared with the general population. This was increased in those who took shorter, more frequent rest periods. This study provides new conclusive evidence that the repetitive power grip and flexion involved in rowing increase the prevalence of trigger finger.

Adhesions as a component of the trigger finger: a dynamic sonographic study

We performed a detailed dynamic high-resolution ultrasound examination of the flexor tendons in trigger fingers and compared this with normal contralateral digits. There was a loss of defined linear tendon margins and/or traction of the flexor tendons on the surrounding soft tissue during passive flexion of the distal interphalangeal joint in 17 out of 20 trigger fingers, which indicated adherence to the surrounding tissues. The differential motion between the flexor digitorum profundus tendon and the flexor digitorum superficialis tendons was also lost in ten trigger fingers, which suggested adherence between the tendons. No signs of peritendinous or intertendinous adhesions were found in the healthy control fingers. We conclude that tendon adhesions are present in the majority of trigger fingers. We could not determine a relationship between the severity of triggering and the presence of adherence due to limited sample size.Level of evidence: II.

Comparison of Magnetic Resonance Imaging and Ultrasound Evaluations of Zone II Partial Flexor Tendon Lacerations: A Cadaveric Study

OBJECTIVES

Surgical intervention for zone II high-grade partial flexor tendon lacerations is often required when more than half of the tendon width is torn. Reliable noninvasive tests are critical for optimizing clinical decision making. Our team previously investigated the use of ultrasound (US) for identification of high-grade zone II flexor digitorum profundus lacerations. In this study, we compared magnetic resonance imaging (MRI) to US for the evaluation of high-grade partial flexor tendon lacerations in cadaveric specimens.

METHODS

Dissection of 32 digits in 8 fresh-frozen upper extremity cadaveric specimens was performed. The flexor digitorum profundus tendons were randomized into 3 groups: intact, low-grade laceration, and high-grade laceration. A dynamic US examination was performed by a blinded musculoskeletal radiologist. The same specimens underwent hand coil MRI, which was read by the same blinded radiologist. Magnetic resonance imaging test performance metrics were calculated and compared to those computed for the US evaluation.

RESULTS

For US evaluation of high-grade lacerations, the sensitivity and specificity were 0.5 and 1.0, with positive likelihood ratio (LR+) and negative likelihood ratio (LR-) values of ∞ and 0.50, respectively. The sensitivity and specificity for MRI evaluation were 0.2 and 1.0, with LR+ and LR- values of ∞ and 0.80.

CONCLUSIONS

Both US and MRI are adequate at determining the presence of a high-grade laceration. Magnetic resonance imaging was more specific than US in identification of high-grade partial flexor tendon lacerations. Although less specific, US is a reasonable and less-expensive alternative to MRI when evaluating for clinically significant high-grade partial flexor tendon lacerations.

Characterization of Hand Tendons Through High-Frequency Ultrasound Elastography

Tendon stiffness plays an important role in the tendon healing process, and many studies have indicated that measuring the shear wave velocity (SWV) on tendons relates to their stiffness. Because the thickness of hand tendons is a few millimeters, high-resolution imaging is required for visualizing hand tissues. However, the resolution of current ultrasound elastography systems is insufficient. In this study, a high-frequency (HF) ultrasound elastography system is proposed for measuring the SWVs of hand tendons. The HF ultrasound elastography system uses an external vibrator to create shear waves on hand tendons. Then, it uses a 40-MHz HF ultrasound array transducer with ultrafast ultrasound imaging technology to measure the SWV for characterizing hand tendons. A handheld device that combines a transducer and a vibrator allows the user to scan hand tissues. The biases of HF ultrasound elastography were measured in gelatin phantom experiments and were less than 6% compared to standard mechanical testing approach. Human experiments showed the ability to use HF ultrasound elastography to distinguish different SWVs of hand tendons. The SWVs were 0.73 ± 0.65 m/s and 1 ± 0.54 m/s for flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP), respectively, and 0.52 ± 0.14 m/s and 4.02 ± 0.77 m/s for extensor tendon under stretch and contraction conditions, respectively. The simplicity and convenience of the HF ultrasound elastography system for measuring hand tendon stiffness make it a promising tool for evaluating the severity of hand injuries and the performance of rehabilitation after hand injuries.

Ultrasound Features of Trigger Finger: Review of the Literature

Trigger finger is a common pathologic condition of the digital pulleys and flexor tendons in the hand. The key clinical finding is a transient blockage of the digit when it is flexed with subsequent painful snapping when it is extended. Imaging is a helpful guide for establishing the severity of the disease, identifying the underlying cause, and deciding the appropriate management. This narrative review aims to recall the anatomic and pathologic bases and describe the ultrasound features of trigger finger, also including common ultrasound findings and complications after therapy. Ultrasound enables an accurate static and dynamic evaluation of trigger finger as well as a comparison with the adjacent normal digits and thus should be considered the radiologic modality of first choice for its diagnosis.

Diagnostic accuracy of imaging modalities in the detection of clinically diagnosed de Quervain's syndrome: a systematic review

OBJECTIVES

To collate and synthesise the literature to provide estimates of the diagnostic accuracy of imaging modalities, and summarise the reported imaging findings associated with de Quervain's syndrome.

MATERIALS AND METHODS

A systematic search was performed in seven databases (MEDLINE, EMBASE, CINAHL, Cochrane Library, PROSPERO, Web of Science, and ProQuest Dissertations & Theses Global). Two reviewers independently performed screening, data extraction and quality assessment using a modified Quality Assessment of Diagnostic Accuracy Studies-2. Measures of diagnostic accuracy were summarised for different modalities and imaging findings.

RESULTS

Twenty-two studies were included, reporting ultrasound, magnetic resonance imaging, X-ray and scintigraphy findings. Reported imaging findings included sheath effusion, retinaculum thickening, subcutaneous oedema, tenosynovitis, hypervascularity, increased tendon size, bony erosion, apposition, calcific lesions and increased uptake on scintigraphy. The most commonly reported imaging findings related to the tendon sheath, with a sensitivity ranging from 0.45 to 1.00 for thickening, and 0.29 to 1.00 for effusions. The risk of bias of studies is largely unclear owing to a lack of reported detail.

CONCLUSIONS

The accuracy of imaging in the diagnosis of de Quervain's syndrome is unable to be determined because of the quality of the studies included. Ultrasound is the most frequently studied imaging modality and may be the modality of choice in clinical practice. Further research involving both symptomatic and asymptomatic participants and clear definitions of abnormal findings are required to better evaluate the effectiveness of imaging in identifying de Quervain's syndrome.

Effect of metacarpophalangeal joint position on A1 pulley and flexor digitorum tendons in trigger digit

BACKGROUND

The aim of this study was to evaluate and compare the cross-sectional area (CSA) of flexor digitorum tendons and the thickness of first annular (A1) pulleys between contralateral normal digits and trigger digits (TDs) at positions of finger flexion and extension using a noninvasive ultrasound system.

METHODS

Seventeen affected fingers of 17 patients (6 men and 11 women) with TDs in one hand, and 17 contralateral normal digits without trigger finger symptoms were examined. The sonographic appearances of flexor digitorum tendons and A1 pulleys were observed at two positions of metacarpophalangeal (MCP) joint flexion: 0° and 60°.

RESULTS

The findings of this study indicate that CSA of flexor digitorum tendons and A1 pulley thickness were significantly larger in both positions of 0° and 60° flexion of MCP joint compared with contralateral normal digits (p < 0.01). In TDs, there was a significantly thicker A1 pulley at 60° flexion of MCP joint than that at 0° flexion (p < 0.01), but no significant change on CSA of flexor tendons.

CONCLUSION

Our results suggested that TDs lead to the thicker A1 pulley and larger CSA of the flexor digitorum tendons. The mismatch in volume change between CSA of flexor digitorum tendons and A1 pulley thickness during MCP flexion may lead to the trigger phenomenon.

Comprehensive simulation on morphological and mechanical properties of trigger finger - A cadaveric model

Trigger finger has long been a common disorder in hand orthopedics. To clarify the unknown causative factors regarding the disease, numerous experiments were done on human cadavers, including tendon forces, tendon moment arm, mechanical properties of the pulley, gliding resistance, etc. However, most of these studies were conducted on normal fingers. As the etiology of trigger finger is still controversial on whether it is an outcome of tendon nodule or pulley scarring, in this study, a trigger finger model was built combining both the nodule created by silicone gel injection and pulley constriction by external compression. Indentation and gliding resistance tests were performed on cadaveric specimens to verify the model. Results showed that after silicone gel injection into the tendon, a significant increase in thickness was found. In addition, no significant difference was found in the toe region compressive modulus of the tendon after injection. Moreover, maximum, drop of gliding resistance and work of extension were all found to be significantly larger as the severity of triggering increased. Our results indicated we have developed a feasible cadaver model simulating trigger finger nodule which could be utilized for further experiments to elucidate other causative factors and biomechanical features of trigger finger in the future.

'Deep Koebner' phenomenon of the flexor tendon-associated accessory pulleys as a novel factor in tenosynovitis and dactylitis in psoriatic arthritis

OBJECTIVES

Skin and joint involvement in psoriasis (PsO) and psoriatic arthritis (PsA) are thought to relate to the so-called Koebner response. Given that dactylitis is non-randomly distributed in the digits, this study tested the hypothesis that the accessory pulleys linked to the flexor tendons were thickened in PsA and thus exhibited koebnerisation.

METHODS

Ninety-six subjects (27 PsA, 27 rheumatoid arthritis (RA), 23 PsO and 19 healthy controls (HCs)) were enrolled. The A1, A2 and A4 pulley thickness was measured using a high-resolution probe (22 MHz). All patients were in remission or low disease activity with current dactylitis being excluded.

RESULTS

Within 864 pulleys investigated, patients with PsA had thicker pulleys in every digit compared with both RA (P<0.001 and P=0.003) and HCs (P<0.001). RA and PsO groups had some pulleys in some digits thicker than HCs whereas some others were comparable. The second digit A1 pulley thickness was higher in patients with PsA with previous dactylitis (P=0.020). More pulleys were thickened in the PsA group (165/243, 68%) than RA (41/243, 17%; P<0.001) and HCs (13/171, 7.6%; P<0.001).

CONCLUSIONS

In established PsA, the accessory pulleys are thickened compared with RA, PsO or HCs and especially in subjects with a history of dactylitis. These findings implicate the involvement of pulleys in PsA-related tenosynovitis and dactylitis supporting the idea of deep koebnerisation in dactylitis and sites of high physical stress.

Quantitative Assessment of First Annular Pulley and Adjacent Tissues Using High-Frequency Ultrasound

Due to a lack of appropriate image resolution, most ultrasound scanners are unable to sensitively discern the pulley tissues. To extensively investigate the properties of the A1 pulley system and the surrounding tissues for assessing trigger finger, a 30 MHz ultrasound system was implemented to perform in vitro experiments using the hypodermis, A1 pulley, and superficial digital flexor tendon (SDFT) dissected from cadavers. Ultrasound signals were acquired from both the transverse and sagittal planes of each tissue sample. The quantitative ultrasonic parameters, including sound speed, attenuation coefficient, integrated backscatter (IB) and Nakagami parameter (m), were subsequently estimated to characterize the tissue properties. The results demonstrated that the acquired ultrasound images have high resolution and are able to sufficiently differentiate the variations of tissue textures. Moreover, the attenuation slope of the hypodermis is larger than those of the A1 pulley and SDFT. The IB of A1 pulley is about the same as that of the hypodermis, and is very different from SDFT. The m parameter of the A1 pulley is also very different from those of hypodermis and SDFT. This study demonstrated that high-frequency ultrasound images in conjunction with ultrasonic parameters are capable of characterizing the A1 pulley system and surrounding tissues.

Correlation Between Sonographic and In Vivo Measurement of A1 Pulleys in Trigger Fingers

The thickness of 210 A1 pulleys of 21 male and female healthy volunteers in two different age groups (20-35 y and 50-70 y) were measured by ultrasound. In a second group, the thickness of 15 diseased A1 pulleys and 15 A1 pulleys of the corresponding other hand of 10 patients with the clinical diagnosis of trigger finger were measured by ultrasound. During open trigger finger release, a strip of A1 pulley was excised and immediately measured using an electronic caliper. The average pulley thickness of healthy volunteers was 0.43-0.47 mm, compared to 0.77-0.79 mm in patients with trigger finger. Based on the receiver operating characteristic (ROC) curve, a diagnostic cut-off value of the pulley thickness at 0.62 mm was defined in order to differ a trigger finger from a healthy finger (sensitivity and specificity of 85%). The correlation between sonographic and effective intra-operative measurements of pulley thickness was linear and very strong (Pearson coefficient 0.86-0.90). In order to distinguish between healthy and diseased A1 pulleys, 0.62 mm is a simple value to use, which can be applied regardless of age, sex, body mass index (BMI) and height in adults.

Identification of the Position and Thickness of the First Annular Pulley in Sonographic Images

The purpose was to identify the A1 pulley's exact location and thickness by comparing measurements from a clinical high-frequency ultrasound scanner system (CHUS), a customized high-frequency ultrasound imaging research system (HURS) and a digital caliper. Ten cadaveric hands were used. We explored the pulley by layers, inserted guide pins and scanned it with the CHUS. After identifying the pulley, we measured each long finger's thickness using the CHUS and excised the pulley to measure its thickness with a digital caliper and the HURS. The thin hypo-echoic layer was revealed to be the synovial fluid space, and the pulley appears hyper-echoic regardless of scan direction. We also defined the pulley's boundaries. Moreover, the CHUS provided a significantly lower measurement of the pulley's thickness than the digital caliper and HURS. Likewise, based on the digital caliper's measurement, the HURS had significantly lower mean absolute and relative errors than the CHUS.

Comparison of the Thickness of Pulley and Flexor Tendon Between in Neutral and in Flexed Positions of Trigger Finger

Objective:

This study aims to compare the morphology of the A1 pulley and flexor tendons in idiopathic trigger finger of digits other than the thumb between in neutral position and in the position with the interphalangeal joints full flexed and with the metacarpophalangeal (MP) joint 0° extended (hook grip position).

Method:

A total of 48 affected digits and 48 contralateral normal digits from 48 patients who initially diagnosed with idiopathic trigger finger were studied sonographically. Sonographic analysis was focused on the A1 pulley and flexor tendons at the level of the MP joint in the transverse plane. We measured the anterior-posterior thickness of A1 pulley and the sum of the flexor digitorum superficialis and profundus tendons, and also measured the maximum radialulnar width of the flexor tendon in neutral and hook grip positions, respectively. Each measurement was compared between in neutral and in hook grip positions, and also between the affected and contralateral normal digits in each position.

Results:

In all the digits, the anterior-posterior thickness of flexor tendons significantly increased in hook grip position as compared with in neutral position, whereas radial-ulnar width significantly decreased. Both the A1 pulley and flexor tendons were thicker in the affected digits as compared with contralateral normal digits.

Conclusion:

The thickness of flexor tendons was significantly increased anteroposteriorly in hook grip position as compared with in neutral position. In trigger finger, A1 pulley and flexor tendon were thickened, and mismatch between the volume of the flexor tendon sheath and the tendons, especially in anterior-posterior direction, might be a cause of repetitive triggering.

Sonographic Findings of Common Musculoskeletal Diseases in Patients with Diabetes Mellitus

Diabetes mellitus (DM) can accompany many musculoskeletal (MSK) diseases. It is difficult to distinguish the DM-related MSK diseases based on clinical symptoms alone. Sonography is frequently used as a first imaging study for these MSK symptoms and is helpful to differentiate the various DM-related MSK diseases. This pictorial essay focuses on sonographic findings of various MSK diseases that can occur in diabetic patients.

Inflammation in Tendon Disorders

The role of inflammation in tendon disorders has long been a subject of considerable debate. Developments in our understanding of the basic science of inflammation have provided further insight into its potential role in specific forms of tendon disease, and the circumstances that may potentiate this. Such circumstances include excessive mechanical stresses on tendon and the presence of systemic inflammation associated with chronic diseases. In this chapter a brief review of the basic science of inflammation is provided and the influence that it may play on tendons is discussed.

Sonographic evaluation of effects of the volar plate on trigger finger

BACKGROUND

We evaluated trigger fingers ultrasonographically and clarified differences between fingers with and without continuous locking or snapping symptoms according to the thicknesses of the A1 pulley, flexor tendon and volar plate.

METHODS

We evaluated 26 trigger fingers, divided into two groups: Group 1, 14 fingers with locking or snapping; and Group 2, 12 fingers without such symptoms. We also evaluated 26 contralateral fingers as controls (Control 1 and 2 groups). We compared each group to the respective control group according to thickness of the A1 pulley and volar plate, and cross-sectional area of the flexor tendon. In addition, nine fingers with locking or snapping and treated using corticosteroid injection were evaluated according to symptoms and sonographic findings 3-4 weeks after treatment.

RESULTS

Thickness of the A1 pulley and cross-sectional area of the flexor tendon were greater in both Groups 1 and 2 than in controls. Thickness of the volar plate was greater in Group 1 than in Control 1, although no significant difference was seen between Group 2 and Control 2. In Group 1, eight of the nine fingers showed an alleviation of locking or snapping symptoms with corticosteroid injection, and sonographic findings showed that thickness of the volar plate was significantly decreased with corticosteroid injection, in addition to reduced thickness of the A1 pulley.

CONCLUSION

In addition to thickening of the A1 pulley, thickening of the volar plate may represent an important contributor to continuous snapping or locking symptoms.

Sonographic findings of extensor digiti minimi triggering caused by thickened extensor retinaculum

Trigger finger is a common well recognized condition and involves the flexor tendons at the A1 pulley in the palm. Triggering of the extensor tendons is a very rare clinical entity. We report a rare case of extensor triggering of little finger caused by constriction of the extensor digiti minimi by a markedly thickened extensor retinaculum (ER) at the wrist, well delineated dynamically by real-time high-resolution ultrasound. The patient underwent release of thickened ER and was asymptomatic immediately.

Mucopolysaccharidoses

The mucopolysaccharidoses (MPSs) are a group of rare genetic disorders of glycosaminoglycan catabolism, caused by a deficiency of lysosomal enzymes required for GAG degradation. Incomplete breakdown of glycosaminoglycans leads to progressive accumulation of these substances in many tissues throughout the body. Different residual enzymatic activity can result in different phenotypes of the same MPS disorder, from severe to attenuated. Musculoskeletal manifestations are common across all forms of MPS. Skeletal and joint abnormalities are prominent features of many MPS disorders, particularly attenuated phenotypes. However, diagnostic delays occur frequently for patients with an MPS, especially those with more attenuated forms of disease. In the absence of appropriate treatment, these conditions are chronic, progressive and often debilitating, but treatment for many types of MPS is now available. Therefore, increasing awareness of MPS among rheumatologists is extremely important.

Sonographic analyses of pulley and flexor tendon in idiopathic trigger finger with interphalangeal joint contracture

This study investigated the sonographic appearance of the pulley and flexor tendon in idiopathic trigger finger in correlation with the contracture of the interphalangeal (IP) joint in the thumb or proximal IP (PIP) joint in the other digits. Sonographic measurements using axial images were performed in 177 affected digits including 17 thumbs and 34 other digits judged to have IP or PIP joint contracture and 77 contralateral control digits. The A1 pulley of the contracture group was significantly thicker than that of the non-contracture group in all digits, whereas the flexor tendon was thicker only in digits other than the thumb. In the analysis using calculated cut-off values, A1 pulley thickening in the thumb and A1 pulley and flexor tendon thickening in the other digits showed statistically significant correlations with IP or PIP joint contracture. This study sonographically confirmed previous reports showing that enlargement of the flexor tendons contribute to the pathogenesis of PIP joint contracture.

The Strain Index and ACGIH TLV for HAL: risk of trigger digit in the WISTAH prospective cohort

OBJECTIVE

The objective of this study was to investigate the association between job physical exposure (JPE) and incidence of flexor tendon entrapment of the digits (FTED).

BACKGROUND

FTED, commonly known as trigger digit, is associated with age, gender, and certain health disorders. Although JPE has been suggested as a risk factor for FTED, there are no prospective cohort studies.

METHOD

A cohort of 516 workers was enrolled from 10 diverse manufacturing facilities and followed monthly for 6 years. Worker demographics, medical history, and symptoms of FTED were assessed. JPE was individually measured using the Strain Index (SI) and American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value for hand activity level (TLV for HAL). Changes in JPE (assessed quarterly) and symptoms (assessed monthly) were recorded during follow-up. FTED was defined as demonstrated triggering on examination.

RESULTS

Point prevalence of FTED at baseline was 3.6%. During follow-up there were 23 incident FTED cases (left and/or right hands). The incident rate for first occurrence of FTED from enrollment was 1.38 per 100 person-years. Risk factors were JPE, age, gender, diabetes mellitus, carpometacarpal osteoarthrosis, and rheumatoid arthritis. In multivariate models, the SI showed strong association with risk of FTED when treated as a continuous variable and marginal association when dichotomized (SI > 6.1). TLV for HAL showed a statistical trend of increasing risk of FTED using the ACGIH limits, but no association as a continuous variable.

CONCLUSIONS

Both JPE and personal risk factors are associated with FTED development. The SI and TLV for HAL are useful tools for estimating JPE.

The value of high-frequency ultrasonographic imaging for quantifying trigger digits: a correlative study with clinical findings in patients with different severity grading

Trigger digit is recognized as thickening and constriction of the flexor tendon sheath at the base of digits. This study investigates the correlation between the severity grading of trigger digits and clinical findings from high-frequency ultrasonography. We measured and compared thicknesses, areas and pathological changes of the flexor digit tendons among total, contracture and noncontracture trigger digits and noninvolved contralateral digits. Forty-seven patients with 55 idiopathic trigger digits (36 contracture and 19 noncontracture) and 55 noninvolved contralateral digits were examined using high-frequency ultrasonography. The thickness of the flexor tendons was measured in a longitudinal plane at the A1 pulley: Inlet (metacarpal head-neck junction), Outlet (proximal phalangeal base-shaft junction) and Interpulley (middle of Inlet and Outlet). The cross-sectional and extratendinous tissue areas of the flexor tendons in a transverse plane at the point of Interpulley were measured. Pathological changes including irregular internal echotextures, fluid collection, dominant A1 pulley and abnormal metacarpophalangeal joint were analyzed. All thicknesses and areas of total and contracture trigger digits were significantly greater than those of noninvolved contralateral digits (p < 0.05), whereas no significant difference was observed in noncontracture trigger digits. The pathological changes were all significantly different from noninvolved contralateral digits in total, contracture and noncontracture trigger digits (p < 0.05). In contracture and noncontracture trigger digits, there were significant differences only in the thickness of the Inlet and the pathological change of the dominant A1 pulley (p < 0.05). In conclusion, the results of the ultrasonographic measurements and findings provided evidence of Notta's node and correlated with clinical findings and severity grades.

Sonographic appearance of the flexor tendon, volar plate, and A1 pulley with respect to the severity of trigger finger

PURPOSE

To evaluate trigger digits with sonography to determine morphological changes in the A1 pulley, flexor tendon, and volar plate in relation to the severity of triggering.

METHODS

We evaluated 67 trigger digits and graded them into 1 of 4 groups. We compared the groups according to severity and to contralateral fingers, which served as controls.

RESULTS

The thickness of the flexor tendons under the A1 pulley was proportional to the severity of triggering. The anteroposterior thickness of the flexor tendon increased significantly among the grades exhibiting triggering regardless of the affected digit. However, in digits other than the thumb, tendon thickness increased even in the absence of active triggering. Thickening tended to be greater with finger flexion. The A1 pulley exhibited the greatest thickness and the volar plate exhibited significant thickening in the group that exhibited continuous triggering that was easily reduced with active extension (grade III).

CONCLUSIONS

The flexor tendon thickened significantly before patients experienced triggering except in the thumb. In the thumb, the flexor tendon and A1 pulley thickened significantly only after patients exhibited triggering. Thickening of the volar plate appears to have an important role in continuous triggering. Although most clinicians can easily determine the severity of a trigger digit by clinical examination, ultrasound might be helpful for objectively understanding the severity and response to treatment, by examining the thickness of the flexor tendon and A1 pulley. In particular, sonographic measurement of the A1 pulley might be useful in judging the progression of trigger finger severity. In cases where a Doppler signal is detected inside the A1 pulley, more conservative therapies might be worth considering before surgery.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic ΙΙΙ.

Musculoskeletal interventional ultrasonography: the upper limb

Forty percent of the 823 ultrasound-guided injections performed in our centre over a year and a half concerned the upper limb, injections involving the shoulder, for subacromial bursitis and the treatment of calcific tendinitis, being the prime indications (24%). The wrist represented 8% of the prescriptions, for treatment of tendinopathy, ganglion cysts, carpal tunnel syndrome and rhizarthrosis. Trigger finger, tenosynovitis and pulley ganglia made up 6% of the indications and the elbow 2.5%. Ultrasound improves the accuracy of the procedure by helping guide the path of the needle and allowing the distribution of the substance injected to be visualised. We shall give details of the technique used for each indication, with advice and hints and post-procedure recommendations.

Imaging of snapping phenomena

Snapping phenomena result from the sudden impingement between anatomical and/or heterotopical structures with subsequent abrupt movement and noise. Snaps are variously perceived by patients, from mild discomfort to significant pain requiring surgical management. Identifying the precise cause of snaps may be challenging when no abnormality is encountered on routinely performed static examinations. In this regard, dynamic imaging techniques have been developed over time, with various degrees of success. This review encompasses the main features of each imaging technique and proposes an overview of the main snapping phenomena in the musculoskeletal system.

Stenosing tenosynovitis

Tenosynovitis refers to an inflammatory condition involving the synovial sheath of a tendon. Stenosing tenosynovitis is a peculiar entity caused by multiple factors, including local anatomy, mechanical factors, and hormonal factors. The main forms include de Quervain tendinopathy; trigger finger (stenosing tenosynovitis involving the flexor digitorum tendons); stenosing tenosynovitis of the extensor carpi ulnaris, extensor carpi radialis, or extensor comunis tendons; stenosing tenosynovitis of the flexor hallucis tendon; and stenosing tenosynovitis of the peroneal tendons. The cardinal finding on ultrasonography is the presence of a thickened retinaculum or pulley that constricts the osseofibrous tunnel through which the tendon runs.