MR imaging findings of trigger thumb

Ultrasound versus MRI in the evaluation of the thumb metacarpophalangeal joint

An intricate and unique combination of ligamentous, fibrocartilaginous, and osseous structures stabilize the thumb metacarpophalangeal joint. Both ultrasound and high-resolution magnetic resonance imaging are extremely useful in evaluating these critical structures. This article reviews common injuries of the thumb metacarpophalangeal joint, while highlighting the merits, limitations, and pitfalls of the two imaging modalities. A clear appreciation of each method, paired with anatomic knowledge, will lend greater confidence and accuracy to diagnosing impactful injuries and guiding intervention.

Ultrasound visualization of the thumb annular pulleys: A cadaveric validation study

BACKGROUND

The thumb annular pulley system is unique from the other digits and is integral to normal thumb function. Injuries to this pulley system can present a diagnostic challenge. No prior study has evaluated the ability of ultrasound (US) to evaluate all four thumb pulleys.

OBJECTIVE

To validate the sonographic visualization of all four thumb pulleys.

DESIGN

Prospective cadaveric laboratory investigation.

SETTING

Academic center procedural skills laboratory.

PARTICIPANTS

Twelve unembalmed cadaveric hands from seven adult male donors ages 78-89 years with body mass index 21.9-26.6 kg/m² .

INTERVENTIONS

Based on anatomic descriptions, a single examiner used a standardized protocol and high-frequency linear transducers to identify the A1, variable (Av), oblique (Ao), and A2 pulleys of the thumb in 10 cadaveric hands. As part of the validation process, the presumed Ao pulley was injected with diluted colored latex using US guidance. Two additional cadaveric specimens were dissected for detailed study of the thumb pulley system.

MAIN OUTCOME MEASURES

Correlation between the four anatomic pulleys as revealed by dissection and the US findings, including identification of latex location with respect to the Ao pulley.

RESULTS

US correctly identified all four thumb pulleys as distinct anatomic structures and the sonographic appearance of the pulleys correlated with the dissection in all 10 specimens. Latex was observed in the Ao pulley in 100% of the cadavers.

CONCLUSIONS

Ultrasound can be used to accurately identify all four thumb pulleys, including distinct Ao and Av pulleys, and should be considered in the evaluation of thumb pulley injuries. This is the first study to validate the US visualization of the annular pulley system of the thumb.

Morphometric study of percutaneous A1 pulley of thumb release

Through anatomy, microscope, histopathology, and simulating needle knife operation on specimens, to accumulate the relevant parameters of the A1 pulley of thumb, and to provide an anatomical evidence for the needle knife therapy of stenosing flexor tenosynovitis. A total of 20 fingers were selected from 20 intact adult upper limb specimens, a small amount of emerald green waterproof dye was injected from the needle insertion point, dissected layer by layer, and the A1 pulley and neurovascular bundle were observed. Observe the loosening of the thumb A1 pulley after 5 and 10 times of simulated needle knife cutting on the specimen; observe the relationship between the needle knife entry point and the A1 pulley under the thumb extension and abduction, and the thumb extension neutral position respectively; further observe the histological characteristics, and the relationship between needle entry point and A1 pulley by microscope. ① In general observation, the A1 pulleys of each finger were transverse fibers perpendicular to the flexor tendon, tough in texture, connected with synovial fibers at the proximal end. It is difficult to distinguish, and connected with oblique fibers at the distal end. ② The release rate of the thumb A1 pulley after 5 and 10 times of simulated needle knife cutting on the specimen were (40.46 ± 2.22)% and (63.52 ± 4.49)%, respectively. ③ In the neutral position of the thumb straightening, the needle entry point is 3.06 ± 0.14 mm from the proximal side of the proximal edge of the A1 pulley, which overlaps with the needle entry point where the thumb is straight and abducted. ④ Observed under a microscope, the A1 pulley is a dense transverse fiber with a pale yellow dense connective tissue, both ends are continuous with the synovial fibers. It is thin and translucent, and loose connective tissue. The A1 pulley is a dense transverse fiber with a pale yellow dense connective tissue. The anatomical key points of the needle knife therapy lie in the extended and abducted position of the thumb. Currently, it is believed that cutting the proximal edge of the A1 pulley is sufficient, and there is no need to cut the entire A1 pulley.

Morphometric study of pulleys of the thumb

Pulleys are thickened regions in flexor tendons sheaths of the digits. They are essential and act as fulcrum for the flexion and extension of the digits. The arrangement and number of pulley system differs greatly between the thumb and other digits. There is paucity of literature regarding the pulley system of thumb. We aimed to study the morphometry of the pulley system of the thumb in Indian cadavers. Dissection was carried out in 55 adult human cadaveric thumbs. The most common morphologic pattern of pulley observed in the thumb is type III (30 thumbs). The least observed is type I (4 thumbs). The mean width and standard deviation of A1, Av, oblique, and A2 pulleys are 5.06±0.87, 5.38±1.22, 4.68±1.13, and 6.04±1.41 mm, respectively. The gap distances between the pulleys were also measured. The results obtained from the present study may be helpful in surgical treatment of trigger thumb with less complication and also in reconstruction of the closed rupture of the pulley of the thumb.

Hallux saltans due to stenosing tenosynovitis of flexor hallucis longus: dynamic sonography and arthroscopic findings

Triggering of the toes is rare, with isolated cases reported in the literature involving predominantly the flexor hallucis longus (FHL) tendon, a condition known as "hallux saltans" (HS). We report the dynamic sonographic findings of a 42-year-old female with a 2-month history of ankle pain and triggering of right hallux, consistent with HS. Sonography demonstrated tenosynovitis and focal thickening of FHL at the level of hindfoot, with a fibrous band adjacent to the tendon. Dynamic ultrasound showed triggering and snapping of FHL tendon during hallux flexion and extension, respectively. We present comprehensive documentation of this rare entity, including sonographic still images and cine clips, as well as correlation with arthroscopic surgical findings.

Topographic anatomical landmarks for pulley system of the thumb

PURPOSE

Knowledge of anatomical landmark to pulley system of the thumb is essential in successful treatment of trigger thumb release either by percutaneous or by minimally invasive technique. Though surgical release of trigger thumb is done commonly, there is paucity of data in the literature regarding its surface landmarks. The purpose of this study is to identify palmar surface anatomical landmarks to the pulley system of the thumb.

METHODS

Dissection was performed on 55 fresh frozen adult cadaveric thumbs. The palmar thumb creases were given names as the proximal-proximal crease (PPC) present at the metacarpophalangeal joint, the distal-proximal crease (DPC) over the middle of the proximal phalanx and the distal crease (DC) at interphalangeal joint. The distance between the proximal edges of each pulley to the three thumb creases and longitudinal length of A1, A2, oblique and Av pulley was measured using digital vernier caliper and was expressed in mean and standard deviation.

RESULTS

The proximal edge of A1 pulley was 1.98 ± 1.61 mm proximal to the PPC. The mean longitudinal length of the A1 pulley was measured to be 5.06 ± 0.87 mm, so the distal edge of the A1 pulley was calculated to lie 3.08 mm distal to PPC. The proximal edge of Av and oblique pulley was situated 7.78 ± 2.5 and 15.72 ± 3.22 mm distal to PPC, respectively. The proximal edge of A2 pulley was very nearer and 2.88 ± 1.79 mm proximal to DC.

CONCLUSION

The knowledge of anatomical skin surface landmarks is helpful in the percutaneous release or minimally invasive procedure. The PPC serves as a definite landmark for A1, Av and oblique pulley whereas it is the DC for A2 pulley.

Short-term Versus Long-term Outcomes After Open or Percutaneous Release for Trigger Thumb

Good outcomes have been reported after both open and percutaneous surgery to release trigger thumb. This study evaluated short-term and long-term outcomes after treatment of trigger thumb with open or percutaneous release. A total of 126 trigger thumbs in 107 patients were reviewed from 2009 to 2012. Short-term (3 months) and long-term results (2 years) and complications of open release (58 digits) and percutaneous release (68 digits) were recorded and compared. Short-term complications included pain occurring in 9 digits (15.5%) in the open release group and in 2 digits (2.9%) in the percutaneous release group and scarring in 4 digits (6.9%) only in the open release group. Long-term complications included pain in 13 digits (19.1%) in the percutaneous release group and in 4 digits (6.9%) in the open release group; in addition, recurrent triggering occurred in 6 digits (8.8%) in the percutaneous release group and in 2 digits (3.4%) in the open release group. Pain and patient satisfaction were significantly better in the percutaneous release group in the short term, but they were better in the open release group in the long term. Although percutaneous release for trigger thumb is a safe and quick procedure, with good short-term outcomes, open release may provide better long-term outcomes. [Orthopedics. 2017; 40(1):e131-e135.].