Management of stenosing flexor tenosynovitis in primary care.

Abstract

Opening Vignette Madam Liang, a 52-year-old housewife who is right-handed, visited your clinic with complaints of pain and a ‘clicking’ sensation of her right ring finger for the last 3 weeks. She had been managed by her family physician for diabetes mellitus and hypertension over the last 8 years. Her symptoms were initially mild, with only a painful lump over the base of her affected finger. However, of late, she noticed that her ring finger joints would occasionally lock in a flexed position, for which she would need to manually extend using her left hand. She revealed that she had recently picked up gardening as a hobby, which frequently involves repetitive use of handheld gardening tools (e.g. pruning shears) and carrying of heavy watering cans. The self-help remedies she attempted, such as consuming paracetamol and massaging her ring finger with Chinese medicated oil, provided minimal relief. She was frustrated that the pain had begun to interfere with her other household chores and was keen for treatment.WHAT IS STENOSING FLEXOR TENOSYNOVITIS? Stenosing flexor tenosynovitis is a common hand disorder with characteristic symptoms of pain, catching, snapping or loss of function of the affected digit. Commonly referred to as ‘trigger finger’ in clinical practice, this informal name is derived from the classical phenomenon of locking of the digit elicited by flexion or extension of the finger. Normally, during finger flexion, the flexor tendon glides smoothly under its anchoring pulleys [Figure 1]. In trigger finger, however, pathological metaplasia and thickening of the pulley structures[1] cause friction and entrapment of the underlying flexor tendon during finger manoeuvres. This impingement corresponds to the classical symptom of painful ‘catching’ of the finger experienced by the patient. Typically, the first annular pulley (A1) located over the metacarpophalangeal joint is most frequently affected. The dominant hand is also observed to be the more susceptible side, with the thumb, middle and ring fingers being the most affected digits.[2,3]Figure 1: Illustration of the finger pulley system shows that it comprises of five annular (A1 to A5) and three cruciform pullets (C1 to C3) through which the flexor tendons run. PA: Palmar aponeurosis [Reproduced with permission from: Peters-Veluthamaningal C, van der Windt DA, Winters JC, Meyboom-de Jong B. Corticosteroid injection for trigger finger in adults. Cochrane Database Syst Rev 2009;21:CD005617].HOW CAN ONE MINIMISE THE RISK OF THIS DISORDER? While the exact aetiology is not fully understood to date, studies have postulated that a history of flexor tendon overuse may play a contributory role. Hand manoeuvres involving power gripping and repetitive digital flexion generate high power gradient and local traumatic injury to the finger flexor system.[4] One study observed a higher incidence of trigger finger in labourers who were assigned with unaccustomed tasks at work.[5] However, further data is required before an association between the disease and high-risk occupations can be established. Nevertheless, it may still be prudent to advise patients to avoid such activities to prevent exacerbation of symptoms and mitigate risk of recurrence. In practical terms, patients should be cautioned, especially in occupations involving the use of high-powered vibrating power equipment (e.g. hammer drills, polishers) or hobbies encompassing constant gripping of handheld tools or handlebars (e.g. gardening, biking).[6] HOW IS THIS RELEVANT TO MY PRACTICE? Trigger finger has a bimodal distribution. Its first peak of incidence is seen in children younger than 8 years, while its second peak manifests later in the fifth to sixth decade of life. In the adult (more common) group, women are observed to be more frequently affected.[4] While the lifetime risk of developing trigger finger is estimated to be 2.6% in the general population, diabetics are at a higher predisposition (4%–10%).[7] The prevalence of trigger finger is comparable between patients with type 1 and type 2 diabetes mellitus.[7] Interestingly, in patients with type 1 diabetes mellitus, the incidence of trigger finger correlates more with the duration of the diabetes mellitus rather than glycaemic control. In addition, diabetic patients tend to display a more intractable course of the disease (e.g. multiple digit involvement), longer duration of symptoms as well as poorer response to conservative treatment.[8] Patients with other inflammatory disorders such as carpal tunnel syndrome, De Quervain’s disease, rheumatoid arthritis and gout have also been observed to be more susceptible to developing trigger finger concomitantly [Box 1].[9]Box 1: Conditions associated with higher incidence of trigger finger.WHY IS THIS RELEVANT TO MY PRACTICE? As trigger finger is commonly encountered in primary care, primary care physicians should be familiar with the range of treatment options available, especially because most trigger finger cases can first be safely managed in a primary care setting before the patient is referred to a hand surgeon. At the point of diagnosis, it is important that the physician is adept at patient education and counselling of treatment options. As different treatment modalities have varying success rates, it is also paramount to facilitate the patients’ understanding of their condition and manage their expectations accordingly. Additionally, treatment options such as corticosteroid injections confer procedural risks. Therefore, thorough pre-procedure counselling and skilful injection technique are crucial. Management of trigger finger in primary care also involves prompt recognition of severe and advanced stages of the disease. Early recognition ensures that timely and appropriate referrals are made to a hand surgeon for consideration of definitive surgical intervention. WHAT CAN I DO IN MY PRACTICE? Presentation and early identification Trigger finger is a clinical diagnosis. Unless other diagnoses such as fracture, tumour or infection cannot be safely excluded (e.g. history of preceding trauma), imaging is usually not necessary. Understanding the natural progression of the disease is important in order to identify the disorder at various stages to establish the correct diagnosis. The severity of the disorder can be graded according to Green’s classification [Table 1].Table 1: Green’s classification: four grades of severity of trigger finger.In the early stages of the disease, patients may present with painless clicking or stiffness of the affected digit. Some patients complain of waking up to find the digit locked, with progressive loosening later in the day. As the disease progresses, patients experience painful catching or locking of the finger, which may require passive extension with the unaffected hand (Grade II). Occasionally, patients may not always present with the classical complaints of catching or ‘locking’ of the finger. In fact, some patients first present at the clinic with signs of late stages of the disease (e.g. Grade IIIB), due to initial delay in seeking medical attention when the condition first arose. In contrast to other hand conditions such as gout or rheumatoid arthritis, the joints of the affected digit are usually not swollen or erythematous despite complaints of pain. In trigger finger, a thickened and tender A1 pulley can be palpated just distal to the transverse palmar crease, which further distinguishes it from other hand conditions. The presence of this ‘painful nodule’ and the absence of prior trauma further support the suspicion of trigger finger in Grade IIIB. In the advanced stage, patients may learn to intentionally avoid active use of the finger to evade painful triggering, eventually resulting in the development of fixed finger joint contracture of the proximal interphalangeal joint (Grade IV). The cornerstone of initial trigger finger management includes patient education, risk mitigation, splinting and analgesia; further management will include corticosteroid injection and surgical release. As the efficacy and associated risks of each treatment modality vary significantly, it is important to factor in each patient’s individual preferences, comorbidities, severity of the disorder as well as duration of symptoms. Non-surgical management Splinting, finger exercises, analgesia and activity modification Splinting and tendon gliding exercises are a low-risk and unobtrusive treatment option, particularly for patients who are not keen for more invasive treatments such as corticosteroid injections. Splinting at different times of the day serves separate purposes. While splinting during the day mitigates unintentional overuse of the affected digit during daily activities, night-time splinting obviates locking of the finger during sleep. Various splint forms, such as oval-8 finger splints [Figure 2], are affordable and easily accessible for purchase online.Figure 2: Photo shows oval-8 finger splint.Figure 3: Clinical photograph shows the proper site for corticosteroid injection.Splinting should be combined with flexor tendon gliding exercises, which aids to reduce friction between the thickened tendons and the pulley structures. Simple tendon gliding exercises can be taught by a certified hand occupational therapist or self-learned on multiple online video platforms such as YouTube. Exercises should be performed several times throughout the day with temporary removal of the splint. In addition, patients should be advised against engaging in activities involving strong hand gripping both during and after treatment to minimise the risk of recurrence. Other adjunctive measures such as a short course of non-steroidal anti-inflammatory drugs (NSAIDs) for acute pain relief may also be considered if no contraindications for use are present. Instructions on the optimal duration of splinting vary in literature. In general, a duration of wear of at least 4–6 weeks is recommended. Based on the European HANDGUIDE study, the European Delphi consensus strategy concluded that there is no optimal orthotic regimen, and treatment duration should be individually tailored to each patient’s symptom duration, severity and preferences.[10] Treatment responses also yield a variety of results. Some studies report a resolution of symptoms after splinting in approximately 50%–65% of the patients.[11,12] A local study in Singapore General Hospital (SGH) observed that a combination therapy of splinting, NSAIDs and occupational therapy was more effective than corticosteroid injections in avoiding subsequent surgery in lower-grade trigger digits.[13] However, poorer treatment response has also been associated with longer disease duration, advanced disease stages and comorbidities such as diabetes mellitus.[4] Corticosteroid injections Corticosteroid injections have been widely regarded as the mainstay of conservative treatment. A highly viable and efficacious treatment modality, it can be administered immediately with prompt pain relief within 10–20 days.[14] While its efficacy has been reported to be as high as 93%, the risk of recurrence is not trivial, with an overall long-term treatment success reported as low as 45% after the first injection in some studies.[15,16] Of note, the success rate is lower in patients with diabetes mellitus, a longer disease duration (>6 months) and multiple digit involvement. Furthermore, patients should be warned that administering more than two injections in a lifetime into the same digit is not recommended due to the risk of tendon rupture. The second dose is also half as likely to be effective if symptoms persist or recur after the first dose.[17] It is important to note that while corticosteroid injections are putative in adult trigger fingers, management in the paediatric population differs and corticosteroid injections should never be administered in affected children. Paediatric trigger finger is a separate condition from adult trigger finger and should not be managed in primary care. Any child presenting with signs of triggering or locking should be referred directly to a hand surgeon for tertiary management. Appropriate pre-procedural counselling on the potential risks and consent taking must be performed by a trained and competent physician with adequate procedural experience. Although relatively uncommon overall, potential complications, including bleeding, iatrogenic infections (e.g. infective flexor tenosynovitis), post-injection steroid flare (30%), neurovascular injury, tendon rupture, skin hypopigmentation, fat atrophy, transient derangement of blood glucose levels (in diabetic patients) and risk of recurrence (30%–40%), may occur. Box 2 provides detailed descriptions on the technique for corticosteroid injection.Box 2: Detailed procedure for corticosteroid injection.Surgical management In severe cases, such as a fixed flexion deformity of the digit (Green’s Grade IV) or a failure of conservative treatment, a referral to a hand surgeon for consideration of surgical release is appropriate. Certain patient groups in particular, such as those with inflammatory arthropathies (e.g. rheumatoid arthritis), pose a higher risk of tendon rupture and should be referred early.[18] Operative treatment involves either open or percutaneous release of the A1 pulley. Overall, the reported success rates are promising (>90%) with a low risk of recurrence.[3] A recent meta-analysis comparing steroid injections with open surgery concluded that open surgical treatment demonstrated a lower recurrence rate compared to injections at 6–12 months post-treatment (relative risk [RR] 0.17, 95% confidence interval [CI] 0.09–0.33). Local retrospective studies observed that the risk of surgical complications (e.g. digital nerve injury, vascular injury and tendon bowstringing) is generally rare (1%) when surgery is performed by an appropriately trained hand surgeon.[19] However, patients should be precautioned of a higher incidence of postoperative pain[20] and recovery time compared to those managed with corticosteroid injections. Generally speaking, surgical intervention should be considered for patients who have intractable disease courses (e.g. high-risk patient groups, initial treatment failure, high recurrence) and are keen for definitive management. WHICH TREATMENT MODALITY SHOULD I CHOOSE? To date, no clear recommendation has been made to conclude which treatment modality is superior in terms of efficacy or safety. A meta-analysis of several randomised controlled trials comparing the three treatment options concluded that steroid injection is an effective modality. However, surgery may still eventually be required for definitive management in the event of relapse.[21] A cost-minimisation analysis in the United States identified that the most cost-effective treatment strategy involves initial management with at least two trials of steroid injections (one injection followed by a second injection for relapse or failure), followed by definitive surgery if required.[19,23] Nevertheless, it is important to note that each treatment option confers its own benefits, risks and limitations [Table 2]. It is important for the primary care physician to discuss these with the patient as well as factor in the patient’s preferences before reaching an informed decision. In other words, choice of treatment of trigger finger should be an individualised one.Table 2: Main treatment modalities of trigger finger.MIMICKERS AND REFERRAL THRESHOLD It is important to recognise other painful hand disorders such as occult fractures, ganglion cysts and infectious or inflammatory arthropathies, as they have similar presentations. Accurate diagnosis is pivotal to avoid inappropriate management. For example, erroneously delivering a corticosteroid injection with underlying suppurative flexor tenosynovitis could result in worsening of infection and potentially lead to the need for a finger amputation. Therefore, it is paramount for clinicians to take a targeted history, such as eliciting any history of trauma, infective symptoms as well as duration and chronicity of the complaint. Imaging modalities such as plain radiographs may also be useful diagnostic adjuncts to further delineate multiple diagnoses from one another. The Appendix provides a summary of the various painful hand conditions and associated features. WHEN TO REFER TO A SPECIALIST? Referral to a hand surgeon is appropriate in the following scenarios: (a) failure of conservative management (e.g. minimal improvement with splinting and/or corticosteroid injection); (b) advanced disease progression (e.g. Grade IV of Green’s classification, locked and irreducible digit); (c) patients desire long-term, definitive intervention (keen for surgical management); (d) complex presentations and unclear pathologies (e.g. multiple digit involvement, possible coexisting injuries such as fracture and tumour); (e) risk of recurrence; and (f) if the patient is a child. TAKE-HOME MESSAGES Trigger finger in adults is a common hand tendinopathy characterised by painful catching or locking of the finger. At-risk groups include the female gender, diabetics and patients with concomitant hand comorbidities. Trigger finger is a clinical diagnosis. Additional radiographic imaging is generally not required unless alternate diagnoses cannot be safely excluded. Suspected causative activities involving repetitive finger flexion and high-powered gripping should be avoided to reduce disease progression or recurrence. It is important for the diagnosing physician to be familiar with initial management of trigger finger. Appropriate management in primary care can improve patient satisfaction, help avoid costly referrals and mitigate high referral burden. Conservative treatment options include splinting and corticosteroid injection. Initial management should always include patient education and counselling on the efficacy and risks of each treatment option. Management of patient’s expectations is important. Patients should understand that a maximum of two injections per digit in a lifetime is recommended. Advanced stages of trigger finger or cases refractory to conservative management warrant referral to a hand surgeon for consideration of surgical intervention. It is important to be cognisant of other painful hand disorders which may mimic trigger finger; for instance, suppurative flexor tenosynovitis is a surgical hand emergency requiring immediate referral to the emergency department for source control. Closing Vignette You explained the diagnosis, available treatment options, and the associated risks and benefits of trigger finger to Madam Liang. In view of the short duration of her symptoms and her preference to avoid needles as much as possible, you advised Madam Liang to try conservative management first. She was given an oval-8 splint and advised to wear the orthosis at night and as often as possible during the day. She was also taught tendon gliding exercises. A short course of ibuprofen for standby pain relief was also provided. Additionally, she was advised to pause her gardening activities for the time being to avoid further exacerbation of her triggering symptoms. Four months later, she shared at her repeat clinic review that her trigger finger symptoms had improved, and she now only needs to wear the splint at night.Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. SMC CATEGORY 3B CME PROGRAMME Online Quiz: https://www.sma.org.sg/cme-programme Deadline for submission: 6 pm, 10 May 2023