Alsancak, Serap PT, PhD; Güner, Senem; Bilgin, Sinan

Stenosing tenosynovitis (SST) of the thumb is a common cause of pain and disability in the hand. Trigger thumb is a form of tenosynovitis that occurs during middle age in healthy women rather than in men and has an increased incidence associated with chronic conditions such as diabetes, rheumatoid arthritis, gout, renal disease, and hypothyroidism.^1–4

Trigger thumb is caused by irritation and inflammation of the flexor tendon, sometimes resulting in the formation of a nodule that impinges on the pulley, causing pain and limited motion. Nodular thickening of the flexor pollicis longus tendon or narrowing of the flexor sheath prevents the flexor tendon from entering into the sheath. In their study, Drossos et al.⁵ showed that the histological abnormalities observed in the A1 pulley of trigger digits are characteristic and not related to inflammation and that these abnormalities could be caused by modification or a rise of the mechanical stresses along the flexor tendon.

Triggering presents as discomfort in the palm during movement, which is localized variable to the palm or the metacarpophalangeal (MCP) or interphalangeal (IP) joint in the thumb. The most commonly involved digit is reported to be the ring finger or thumb.^6,7

Various methods have been used to treat trigger thumb. Splinting is one of the conservative treatment methods; splinting reduces or removes tendon excursion through the A1 pulley for a long enough time to allow the synovitis around the pulley to resolve.⁸ Rodgers et al.⁹ reported that treating manual workers who used repetitive hand motions with splint of the distal interphalangeal joint (DIP) joint for six weeks resulted in resolution of symptoms in 53% of patients. Evans et al.¹⁰ found a 73% achievement rate using splint combined with exercise. Patel and Bassini¹¹ reported a 70% success rate in trigger digits using splinting of the MCP joint in 10 to 15 degrees of flexion. Valdes et al.¹² demonstrated a positive relationship between the use of custom thermoplastic orthoses and reduction of pain and SST outcome measures for patients who had isolated trigger finger or trigger thumb. Prior studies have shown pain reduction with carpometacarpal (CMC) stabilization orthosis.^13,14 Rannou et al.¹⁵ reported pain reduction with long-term wear of a nighttime CMC orthosis for patient thumb osteoartrithis.

The aim of this study was to evaluate the comparative final outcome of two different conservative treatment protocols in trigger thumb using three different types of splints. One daily splint was used to restrict IP, and two different night splints were used to restrict MCP and CMC joints of the thumb with an additional exercise program and connective tissue manipulation (CTM).

MATERIALS AND METHODS

The study was based on 43 thumbs of subjects who had 14 bilateral and 15 unilateral trigger thumbs (22 female and 7 male, 15 with diabetes mellitus, 3 with rheumatoid arthritis, 7 with osteoarthritis, 4 with overuse). Participants presented with a painful locking on the thumb and pain during flexion and extension of the thumb for almost six months. Exclusion criteria in this study include participants with more than one trigger finger per hand, trigger thumb with a flexion contracture, and previous A1 pulley release surgery and steroid injections within the past year. Participants were informed of the aims, methods, the anticipated benefits, and potential risk of the study. All participants gave their informed consent signed and witnessed.

TREATMENT PROTOCOL

Participants were divided into two groups using three different types of splints (Table 1 and Table 2). Group A (mean age, 45.53 ± 6.55 years) was instructed to use splint 1 and splint 3. Group B (mean age, 49.6 ± 3.43 years) was instructed to use splint 2 and splint 3. Exercises and CTMs were standard and the same for both groups. Splint 1, used at night, limited the IP, MCP, and CMC joint flexion and extension (Figure 1A, B). Splint 2, used at night, limited the MCP joint and given 15 degrees of flexion position and limited CMC joint hyperextension (Figure 2). Splint 3, used during daytime, only limited IP joint and positioned in 15 degrees flexion (Figure 3).^16,17 Outcome measures were assessed at initiation and 10 weeks after the treatment. During the initial visit, custom-made low-temperature thermoplastic splints were manufactured from solid Orfit (Aquafit NS Stiff, 3.2 mm [1.8 in]; Orfit Company, Inc, Belgium) and mini perforated.

Table 1

Table. No title avai...

Figure 1

Figure 2

Figure 3

Recommended treatment protocol for this study required the subjects to wear the respective night splint depending on which group they were in, along with a day splint and participation in a given exercise program and CTM, which were consistent for both groups. An exercise sheet with diagrams, demonstrating passive IP joint flexion, composite full-thumb flexion, full-thumb extension, active hook exercise, and especially CTM and deep-tissue mobilization technique (wooden spoon exercises) of the thenar muscles and flexor pollicis longus tendon, was given to all participants (Figures 4 and 5).^10,12,18,19 Connective tissue massage is a manual technique used to treat altered connective tissues to modify the local bloodstream and detach involved tissue by connective tissue stretching. Connective tissue manipulation is one style of massage technique and is thought to be an effective therapy, producing general body relaxation, reducing muscle spasm and connective tissue tenderness, and increasing plasma b-endorphins.^20–24 To ease the application, deep tissue mobilization was made using a wooden spoon. Deep tissue mobilization is also performed along the borders of adjacent muscles to release fascial adhering and reduce buildup of scar tissue.^25,26

Figure 4

Figure 5

Patients were instructed to remove the splint to complete these exercise for 10 repetitions and make CTM for three repetitions three times a day.

The preoutcome and postoutcome measures included the stages of SST¹¹ (Table 3), Visual Analog Scale (VAS), and patient-perceived improvement in symptoms. Patel and Bassini¹¹ developed the SST that was used in this study. The physiotherapist determined the triggering grade using the SST scale. The patients rated pain using the VAS (0 indicating no pain and 10 indicating severe pain). The SST and VAS scores were obtained at the initial visit and at the end of 10 weeks of the treatment.

Table 3

STATISTICAL ANALYSIS

Statistical analyses were performed by using SPSS Software Program, version 16.0. Paired samples and Wilcoxon signed rank test were used to compare data pretreatment and posttreatment in trigger thumb patients. The statistical significance level was set at P < 0.05.

RESULTS

All participants wore their splints for 10 weeks. The following preoutcome and postoutcome measures using SST and VAS paint scale (Tables 4 and 5) were found to be significant in determining the efficacy of custom-made thermoplastic splint interventions for trigger thumb. The pretreatment SST score was 3 in group A (2.71 ± 0.46) and group B (2.73 ± 0.45). After 10 weeks of treatment programs, SST scores were significantly decreased in both groups (P < 0.05). Posttreatment SST score was 1 in group A (1.71 ± 0.39) and results in group B (1.4 ± 0.5). Posttreatment VAS and SST scores were compared between group A and group B and were found significantly different in the two groups (Table 6).

Table 4

Table 5

Table 6

An evaluation of the VAS pain score was based on pretreatment 8.03 ± 0.63 in group A and 8.18 ± 0.56 in group B. The VAS pain score was significantly reduced in group A compared with group B (P < 0.05). The posttreatment mean pain score was 2 ± 0.8 in group A and 4.8 ± 0.7 in group B.

DISCUSSION

Trigger finger is more common in middle-aged women and frequently involves the ring finger and thumb.^27,28 The aim of splint intervention is to lessen the friction caused by flexor tendon movement through the affected A1 pulley for a long enough time to allow resolving of inflammation.⁸ We propose that significantly decreased mechanical stress along the flexor tendon can be achieved by using a splint providing restricted IP joint and a free motion MCP, CMC joint with supply supported by the activities of daily living. This study demonstrated a clinically significant improvement using custom-made thermoplastic splints and the subjective reduction of pain and objective SST outcome measures for patients who have isolated trigger thumb.

Conservative management may include splinting to immobilize the MCP joint in extension and to resolve inflammation in the distal region of the palm. Another conservative splinting approach for chronic triggering involves the purchase of a silver ring splint.⁴ Restricting hyperextension of medial or lateral deviation of the proximal IP (PIP) joint can be achieved with a small splint. Evans et al.¹⁰ reported that the MCP joint was immobilized in 0 degrees using a volar-based hand splint allowing full DIP and PIP motion and 73% success rate using a splint in combination with exercises. Colbourn et al.¹⁸ reported that 28 participants felt that their triggering had improved after using a low-profile custom thermoplastic MCP blocking splint at 6 to 10 weeks. The ring splint is designed to restrict MCP joint to approximately 15 degrees of joint flexion and is used to splint day and night.¹⁸

In this study, splint 2 immobilized the MCP joint in 15-degree flexion and restricted CMC hyperextension but gave the IP joint free motion; this splint was worn at night. Splint 1, used at night, immobilized the MCP and IP joints and restricted CMC joint flexion. In addition, splint with strap turning around wrist, the first web space restoration, was placed near the MCP joint positioned at 30-degree flexion and abduction. Moulton et al.²⁹ found the CMC to be most congruent when the MCP joint is positioned in flexion. Rannou et al.¹⁵ reported the use of only nighttime splint that restricted CMC joint motion and positioned first web space.¹⁵ Results of this study indicate that the custom-made thermoplastic splint 1 prominently decreases pain and symptoms of trigger thumb when compared with splint 2. In group A, participants felt that their pain resolved after three weeks. The MCP, IP, and CMC joints were fully restricted at night using splint 1, and this splint was more effective, especially in the reduction of pain.

Splint 3 used in the daytime to immobilize only the IP joint in 15-degree flexion was not circumferential, and because of that, this ring splint ensured IP immobilization, allowing sensorial input of thumb pulp during pinching and increased functional use of the hand in activities of daily living. Valdes et al.¹² demonstrated the efficacy of the splint in the reduction of pain and SST score for patients who had trigger finger and thumb. They mentioned that a splint that allows sensorial and tactile input of thumb pulp had an affirmative effect as treatment.¹² Splint 3 has the same features as the splint used in that study, and both groups used it during the day. Based on our findings, we can say that positioning of the thumb at night may create the efficacy difference between the two protocols (splint 1 + splint 3 had a better outcome than splint 2 + splint 3).

The compliance of participants may have influenced the study results. In this study, all participants fully completed the recommended treatment program of 24-hour splinting. Salim et al.³⁰ studied 74 patients who were treated with 10 sessions of wax therapy, ultrasound, stretching muscle exercises, and massage, yielding 68.8% resolution of symptoms and freedom from symptoms after 6 months. According to his experience, physiotherapy may have a role in the prevention of recurrence of trigger finger. Howitt et al.³¹ studied the efficacy of active release techniques on the treatment of trigger thumb when used in conjunction with the Graston technique that uses metal instruments in place of the subjects’ hands and fingertips. The friction produces shear action on the skin and leads to tissue distortion. Such action may disturb tissue functions and can be harmful to the soft tissue. Because of the high coefficient of friction found in the palm of the hand, we preferred wooden material in this study.³⁴ In this study, a small wooden spoon was used for deep-tissue mobilization and active hook exercises to encourage normal gliding of the tendon in patients. Joint motion and mobilization increased joint and deep tissue mobilization, which caused diminution of pain and swelling. Stretching exercises help to prepare the muscles for strengthening exercises, relieving swelling, and neutralizing the position of the thumbs.^25,32,33

Splint treatment in trigger thumb and a combination of exercise and deep tissue mobilization are feasible, and successful results can be obtained. In particular, a night splint that immobilizes MCP, IP joint, and restriction of CMC joint flexion is quite effective. Although this study had a small sample size, based on our findings, it can be said that appropriate splint treatment, additional exercises, and connective tissue mobilization programs have promising results in the noninvasive treatment of trigger thumb. Further research with larger sample sizes and a variety of different splints, exercises, and CTM could show the ideal noninvasive treatment in trigger thumb.

REFERENCES

KEY INDEXING TERMS: trigger thumb; splint; conservative treatment