Quantitative Measurements of the Cross-sectional Configuration of the Flexor Pollicis Longus Tendon Using Ultrasonography in Patients With Pediatric Trigger Thumb

Changes in flexor pollicis longus tendon cross-sectional dimensions after A1 pulley release for paediatric trigger thumb

In this study, 30 patients with unilateral paediatric trigger thumb were examined with measurements taken within 1 month before surgery, and at 3 months after surgery. We measured the dorsal-palmar (DP) diameter, radioulnar (RU) diameter and cross-sectional area (CSA) of the flexor pollicis longus (FPL) tendon at two sites: just proximal to the A1 pulley and underneath the A1 pulley using ultrasonography. Following surgical A1 pulley release, the DP diameter, RU diameter and CSA of the FPL tendon just proximal to the A1 pulley significantly decreased from 2.6 mm to 2.2 mm, from 5.1 mm to 4.2 mm and from 11 mm2 to 7.8 mm2, respectively. Additionally, the RU diameter and CSA of the FPL tendon at the area beneath the A1 pulley significantly increased from 2.2 mm to 3.2 mm and from 4.3 mm2 to 5.8 mm2, respectively. This finding suggests that the conformation of the FPL tendon of the affected thumb tends to return to that of the contralateral uninvolved thumb after A1 pulley release. Underdevelopment of the inner space around the A1 pulley may contribute to the development of paediatric trigger thumb.Level of evidence: III.

Common Pediatric Hand Anomalies

Upper extremity congenital anomalies in the newborn are second only to congenital heart anomalies. Some of the more commonly encountered upper extremity anomalies are trigger thumb, thumb hypoplasia, polydactyly, syndactyly, and amniotic band syndrome. While some conditions occur in isolation, others are known to commonly occur in association with syndromes. Familiarity with these conditions is important not only to provide adequate evaluation and workup of these patients but also to deliver appropriate surgical intervention and prepare parents with appropriate expectations. In this article, we outline the etiology, classification, surgical management, and outcomes of these five commonly encountered upper extremity congenital anomalies.

The association between trauma and paediatric trigger thumb deformity; experience from a single tertiary referral hospital

Whilst the natural history and management of trigger thumb have been thoroughly investigated, the aetiology of the condition remains poorly understood. There are suggestions that this could be a congenital or acquired condition, but evidence remains limited. A history of trauma has repeatedly been noted in a proportion of patients presenting with trigger thumb. This retrospective study reviewed the presentations of 75 cases of trigger thumb in 65 consecutive children who underwent surgery for trigger thumb. We found that 28% of affected digits presented with a traumatic history to the thumb, of those 90% presented immediately post-injury with a flexion deformity. Those who presented with a traumatic history were typically younger at presentation (median age 27.0 months compared to 37.5 months for traumatic and atraumatic presentations respectively) but also tended to present earlier than the atraumatic group (one day compared to 12.17 months respectively). We conclude that a single traumatic event is unlikely to be the causative factor in the development of trigger thumb in children but it may expediate the development of individuals who are predisposed.

Changes in the flexor pollicis longus tendon during spontaneous resolution of pediatric trigger thumb

The present study aimed to evaluate conformational changes in the flexor pollicis longus (FPL) tendon and inner space of the A1 pulley during spontaneous resolution of pediatric trigger thumb (PTT) and to compare them versus the normal contralateral side. We enrolled 36 patients with unilateral PTT who underwent ultrasonography twice between January 2016 and July 2020 and showed >10° improvement in thumb interphalangeal (IP) joint extension lag. Ultrasonography was used to measure the anteroposterior (AP) and radioulnar (RU) diameters of the FPL tendon proximal to the A1 pulley and of the inner space of the A1 pulley. On the side of the PTT, the average extension lag in the thumb IP joint significantly improved, from 35.6° to 14.2°. The AP and RU diameters of the FPL tendon increased by 0.3% and 1.9%, respectively, and those of the inner space of the A1 pulley increased by 15.3% and 5.0%, respectively. In the contralateral normal thumb, the AP and RU diameters of the FPL tendon increased by 12% and 9.3%, respectively, and those in the inner space of the A1 pulley increased by 9.9% and 4.6%. During improvement in IP joint extension lag, the mismatch between the enlarged FPL tendon and the inner space of the A1 pulley was reduced by their asymmetric growth.

Open Release of Pediatric Trigger Thumb

Open release of a trigger thumb has been shown to be the most reliable option to restore full interphalangeal (IP) joint extension and thus normal thumb-joint motion in children¹. The aim of this procedure is to restore free gliding of the flexor pollicis longus (FPL) tendon in its canal in children with fixed IP joint flexion contractures or those in whom nonoperative treatment modalities have failed.

Description

The surgical procedure is easy to perform and straightforward; however, attention must be given to several details in order to avoid surgical failure and complications. General anesthesia is required for this procedure. The extremity is prepared and draped in a sterile fashion with the patient in the supine position, and a tourniquet is utilized to facilitate surgical dissection. A transverse incision is gently made just adjacent to the thumb metacarpophalangeal (MP) flexion crease, above the so-called Notta nodule. The ulnar neurovascular bundle is retracted to the side, and the Notta nodule, a local enlargement of the FPL tendon², is visualized at the A1 pulley. The pulley is incised longitudinally to allow for full IP joint extension. After verification of full passive motion, the tendon is inspected for any further abnormalities. Then, the tourniquet is released, and the wound is closed with absorbable sutures. We recommend the use of local anesthetics for postoperative pain control. In cases of a trigger thumb stuck in extension, full tenodesis flexion of the IP joint combined with smooth, full passive extension confirms a complete release.

Alternatives

Nonoperative treatment modalities mainly include watchful waiting for spontaneous resolution³, occupational therapy (i.e., passive exercising)^4,5, and splinting therapy⁶. However, prolonged stretching and splinting may move the nodule to a point distal to the stenotic pulley, thus resulting in a trigger thumb locked in extension with a loss of IP flexion. Alternative surgical treatment techniques involve percutaneous trigger thumb release or open release with alternative surgical approaches (e.g., an oblique or Brunner incision)^7,8.

Rationale

Several reports have shown that open release of a trigger thumb leads to the most reliable outcomes in terms of achievement of range of motion and complications^1,9,10. The main advantage of this procedure is the perfect visualization of the FPL tendon beneath the stenotic A1 pulley, which allows for a complete A1 release with clear vision. Such visualization cannot be provided with use of percutaneous techniques, which position the neurovascular bundle in potential danger for iatrogenic injury or may lead to incomplete pulley release⁸. Moreover, the use of this procedure allows parents to avoid the prolonged therapy and splinting associated with nonoperative treatment. Formal rehabilitation is usually not necessary postoperatively.

Expected Outcomes

Open release of a trigger thumb is a safe and reliable option that leads to full range of motion in 95% of children, which is substantially higher than for nonoperative treatment with therapy (55%) and splinting (67%)¹. Even delayed open release may provide satisfactory outcomes⁹. Although spontaneous resolution without surgery has been reported in 63% of cases³, patients with a flexion contracture of >30° showed spontaneous resolution in only 2.5% of cases¹⁰. Furthermore, the open surgical technique has been shown to have a lower rate of complications (around 3.4%)¹¹ compared with percutaneous techniques, which showed a 3.29 times increased risk of recurrence¹² and relevant injury to the neurovascular bundle⁸. If the A1 is fully divided, recurrence is highly unlikely. Postoperative rehabilitation is very quick following open release of a trigger thumb because closure under local anesthesia provides a painless postoperative course, wounds heal within a few days, and children are allowed to resume play immediately once a bandage is applied.

Important Tips

The use of surgical loupes is of paramount importance to safely perform this procedure.Place the skin incision adjacent but not directly onto the palmar MP flexion crease for better scar formation.Divide the skin very gently because the A1 pulley is located directly under the skin, and the FPL and radial nerve can be harmed easily. Retract the ulnar neurovascular bundle aside so as to allow for safe preparation until A1 division.Divide the A1 pulley until the Notta nodule on the FPL can safely glide distally into full IP extension. In some cases with large, distally-sitting nodules, the pulley incision must be extended distally into the oblique bundle.A sign that the entire A1 pulley is released is seeing the corner formed by the distal edge of the pulley and the longitudinal cut in the pulley. Additionally, the cut halves of the fully released pulley will rest completely in the sagittal plane of the thumb, no longer converging over the FPL tendon.Tight bands can exist proximal and distal to the A1 pulley and should be released as well if present.Check for a tight IP volar plate following A1 division, which may require postoperative splinting.For thumbs stuck in extension, tenodesis can be utilized to verify complete A1 release.Utilize absorbable sutures, local anesthesia, and a bulky dressing to allow a comfortable postoperative course.

Acronyms and Abbreviations

IP = interphalangealMP = metacarpophalangealFPL = flexor pollicis longusROM = range of motionANOVA = analysis of variance.

Pediatric Trigger Digits

Pediatric trigger thumb (PTT) and finger (PTF) are upper extremity deformities that frequently go unrecognized by providers. Early recognition by pediatricians and caregivers is vital because PTT is successfully treated nonoperatively in more than 95% of patients if diagnosed early. Similarly, PTF can be successfully treated nonoperatively in 67% of patients. Although PTT is typically benign and 10 times more common, PTF may be associated with underlying concurrent medical conditions, such as juvenile rheumatoid arthritis, diabetes, mucopolysaccharide and lysosomal disorders, and trisomy 18. Routine examinations consisting of full hand range of motion should be performed in all children. Clinicians should be aware of the importance of conservative treatment options for PTT and PTF and the value of screening for underlying medical conditions associated with PTF.

Congenital Disorders of the Pediatric Thumb

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Surgical timing for pediatric trigger thumb treatment is controversial for numerous reasons including the potential for spontaneous resolution, the possibility of bilateral involvement, and anesthesia concerns regarding the developing brain. Hence, a reasonable approach is to delay the surgical procedure until the patient is ≥3 years of age.

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Preaxial polydactyly is usually unilateral and sporadic, with the most common reconstruction method consisting of excision of the diminutive thumb with preservation and soft-tissue reconstruction of the dominant thumb. The surgical procedure is typically performed around the patient age of 1 year to decrease the risks of anesthesia but allow reconstruction prior to the development of a tip-to-tip pinch.

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Triphalangeal thumb and thumb hypoplasia are often found in the setting of systemic anomalies such as Holt-Oram syndrome, thrombocytopenia absent radius syndrome, Fanconi anemia, VACTERL (vertebral anomalies, anal atresia, cardiac anomalies, tracheoesophageal fistula, renal defects, and limb anomalies), and/or Blackfan-Diamond anemia. As such, patients should receive adequate workup for these entities. A surgical procedure should be performed only once patients have been medically cleared.

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The status of the carpometacarpal joint in thumb hypoplasia determines whether reconstruction with first web space deepening, collateral ligament stabilization, and opponensplasty compared with index pollicization is performed.

Pediatric Trigger Digit Presenting in the Setting of Trauma

BACKGROUND

Pediatric trigger digit is a relatively rare condition with incompletely understood etiology. In our practice, we noted a series of children presenting with pediatric trigger digit after an associated local trauma to the hand, which has not been previously described. The aim of this study was to analyze the nature of presentation of trigger digits, the accuracy of initial diagnosis, and the impact on treatment strategies used.

METHODS

An institutional review board-approved retrospective review of our institution's experience with pediatric trigger finger from 2001 to 2015 was performed.

RESULTS

Twenty-two patients with 26 affected digits were identified. Eighty-eight percent of patients were diagnosed with trigger thumb, whereas 3 patients (12%) had small finger triggering. Thirteen patients (59%) presented as outpatients, whereas 9 (41%) presented through the emergency department. All patients presenting to the emergency department were in the setting of recent minor trauma. Of this subset of patients, 67% had an incorrect initial diagnosis, leading to an average delay in treatment of 60 days. Ten patients (45% of total) were initially treated with immobilization versus surgical release of the A1 pulley. However, all but 2 of these patients required eventual A1 pulley release for persistent or recurrent triggering (88%).

CONCLUSIONS

The cause of trigger digit in children remains incompletely understood and may be multifactorial. In this series, a traumatic component to presentation was found in a significant number of patients. This association with minor trauma may contribute to misdiagnosis and delay in definitive treatment. Although initial treatment with immobilization does not seem to impact surgical outcome, we found a high rate of failure with initial immobilization. Most patients required eventual surgical management, regardless of whether or not the initial presentation was associated with trauma. When performed, we found that A1 pulley release alone has safe, reliable results.

Clinical results of splinting versus observation for pediatric trigger thumb

Patients with pediatric trigger thumb present with fixed contracture of the interphalangeal joint (IPJ) or snapping of the thumb. We applied a hand-based dynamic splint using coils at the IPJ. The aim of this study was to report the clinical outcomes of splint therapy versus observation. One hundred twenty-nine thumbs (112 patients and 57 boys) were examined retrospectively. At initial presentation, parents selected the treatment after explanation of pathology and consents were obtained. Treatment was concluded when full extension or resolution of the involved IPJ was achieved; alternatively, surgical treatment was offered for patients who failed to improve. Improvement in extension loss to 0° and hyperextension was defined as resolution of the IPJ. Surgery was not selected as a first-line treatment strategy in any of the cases in this study. The rate of resolution was 59% at 31 months of follow-up in the splint group (99 thumbs) and 43% at 30 months in observation group (30 thumbs); there was no significant difference between the groups (P = 0.15). Twenty-one thumbs showed locking of the IPJ in the extended position during splint therapy, but all recovered with a 71% rate of resolution. The splint group showed a higher rate of resolution than the observation group; however, there was no significant difference between therapies. Our study showed that 55% of patients with pediatric trigger thumb showed resolution following conservative treatment for an average of 30 months until surgery could be performed under local anesthesia. Splint therapy and observation are viable treatment options prior to surgery.