A Customised paediatric thumb web splint for management of adduction contracture of thumb

Abstract

The thumb web has a unique anatomy, the integrity of which is vital to both form and function of the hand. Thumb web space adduction contractures are a common consequence of hand burns and are a progressive disabling deformity and prevention or early intervention is advisable. This case describes the use of a customised removable web splint in children with scarring and gradual contracture of the first web space causing pain with movement and significant restriction in the hand function to maintain the thumb web expansion. This inexpensive and effective appliance can be safely applied to an injured hand, maintain web space following surgical release and allows movement at the first carpometacarpal joint and hence obtains a good functional outcome.

Background

One of the major determinants of the quality-of-life following hand burns is the functionality of the hands, which includes altered eating habits, depression, social isolation and a gradual reduction in activity levels.¹Adequate first web space is essential for a wide range of thumb mobility and hand function activities. The normal web space angle has been found to be 40–60° when measured from two intersecting lines made through the metacarpal bones of thumb and index finger. Thumb web may become contracted following burns, infection, trauma, fibrosis or may be iatrogenic.²

Considering the thumb accounts for 40%–50% of the hand’s function, first web contracture is a significant disability that should be addressed.³ Thumb web contracture is a progressive condition and once established, it will involve all structures, including skin, subcutaneous tissue, muscle, fascia, capsule and ligaments of the first carpometacarpal joint that becomes difficult to treat.⁴

There are various methods to prevent and treat established thumb web contracture, involving splints, external or internal K-wires, release and split-skin grafting, Z-plasty, abdominal or groin flaps, free lateral arm flaps and so on. Some techniques have unpredictable results and may not be practical in the presence of polytrauma or extensive burns. Free flaps are expensive and unavailable in most centres in developing countries.⁵

This case report presents a web spacer for the thumb that can keep the web wide open, preventing or correcting early contracture or preserving surgical correction of severe contracture. The main advantage of this device is that it not only opens the thumb web gradually, but also allows active, assisted active and passive movement of the first carpometacarpal joint.

Case presentation

Case 1

An early teenage boy reported with a chief complaint of pain and restricted movement of the thumb and index finger of right hand (figure 1A). The patient also gave a history of surgery done before 2 weeks for cracker blast injury of right hand. Postoperatively, the patient noted scarring and gradual contracture of the first web space causing pain with movement and significant restriction in the hand function.

Figure 1.

(A) Restricted movement of thumb of right hand due to skin graft. (B) Correct position of hand for impression. (C, D) Alginate impression with the fingers spread apart. (E) Model prepared with dental stone.

Case 2

An early teenage boy reported with a chief complaint of pain and restricted movement of the thumb and index finger of right hand (figure 2A). The patient gave a history of cracker blast injury of right hand and debridement and placement of graft done before 1 week. Postoperatively, the patient noted scarring and gradual contracture of the first web space causing pain with movement and significant restriction in the hand function.

Figure 2.

(A) Postsurgery, restricted movement of thumb of right hand due to skin graft. (B) Impression made with alginate. (C) Model prepared with dental stone.

Treatment

Case 1

The surgical correction was done by skin grafting and K-wire used between thumb and index finger for stabilisation. A customised thumb web splint was planned as the treatment (figure 1B). Alginate impression of the right hand was made with the fingers spread apart with the desired width (figure 1C). Cast poured with type-IV dental stone (figure 1D). Model of the right hand obtained (figure 1E). Acrylic part of the splint was fabricated over the wire framework with two loops around the thumb and index finger and the extensions were approximated each other in the extended position (figure 3A). The appliance was polished and delivered to the patient (figure 3B). Patient advised to wear the splint for the whole day for 2 weeks for a comfortable position of thumb finger until the removal of K-wire. Later, regular exercise with the splint for 30–60 min sessions 2–3 times a day for 2 weeks. The patient and the caregiver were taught about handling of wound care, proper application of splints and exercise to prevent scar formation.

Figure 3.

(A) Acrylic custom splint was fabricated. (B) Insertion of acrylic splint. (C,D) Post-treatment position of finger and the radiograph.

Case 2

A customised thumb web splint was decided as the treatment plan. A wax spacer was designed for the first web space with desired width and the wax spacer was mounted in plaster of Paris (figure 2B), followed by dewaxing and cold mould seal was applied in the plaster model (figure 2C). The acrylic part of the splint was fabricated over the plaster (figure 4A). The appliance was polished and delivered to the patient by stabilising it in the first web space using gauze and elastic strap (figure 4B). Patient is instructed to wear the splint for a minimum of 12 hours a day for 2 weeks with regular exercise for 20–30 min sessions using the ball. The patient and the caregiver were taught about handling of wound care, proper application of splints and exercise to prevent scar formation.

Figure 4.

(A) Insertion of acrylic splint and stabilised gauze and elastic strap. (B) Instructed to do exercise using the ball.

Outcome and follow-up

In both the cases, the patient was able to achieve excellent thumb opposition and abduction, which were his initial deficiencies, as well as improved overall hand function. In case 1, the patient was encouraged to perform active movements of the thumb and hand and the splint was used until healing was complete. Patient recalled within 1 week and after 1 month for periodic review and post-treatment radiograph was taken (figure 3C D). In case 2, the patient was encouraged to perform active movements of the thumb and hand using smiley ball and the splint was used until healing was complete. Patient recalled once in 3 days for about 1 month for periodic review.

Discussion

Development of web contractures is an ongoing process and the amount of time elapsed since the injury increases the severity and hence worsens the prognosis of the web release surgery. Its necessary to achieve satisfactory wound closure and restore functional integrity in the least time.⁶ Three periods of evolution in first web contracture have been described: elastic, reversible and fixed. In elastic first web contracture, which lasts for initial 4–6 weeks full correction can be expected by passive abduction of the thumb and active exercises for strengthening of the abductor muscles. Reversible contractures respond to splinting while fixed contractures will require surgical intervention. Another characteristic of first web space is that because of its triangular shape, small limitations of aperture at its base have a major effect on the extremes of the triangle (the thumb and index pulps).⁷

Thumb web contracture can be easily prevented if anticipated or recognised early. Bhattacharya et al,⁸ stated that scarring at cutaneous and subcutaneous levels causes maximal contractural effect, because of the longer lever arm as we move away from the axis of abduction. Del Pinal et al,⁷ highlighted reduction of oedema and optimal thumb web position, and also recommended splinting.

Splints have an important role, both in attempting to reverse minor contracture and in maintaining the gain achieved by surgical release of the shortened first web. Such splints may be external or internal, static or dynamic, temporary or permanent.⁹ Various forms of splinting have been described: pressure gloves, K-wires, external static and adjustable splints.^{5 10} Temporary external splints of a static nature are usually constructed at the time of surgery from plaster of Paris and may later be replaced by thermoplastic.

Pressure gloves provide inadequate longitudinal traction in the web; Cheng added interdigital straps, but the gloves were still not very effective and more over cannot be used in presence of wounds over the hand.¹¹ K -wire splints provide non-rigid functionally stable fixation. This type of fixation allows bone to heal in a good position of function, so that gliding and good range of motion are achieved.¹² These are effective for prevention but have to be changed as the web opens up.

Burns being a life threatening and disfiguring injury, it makes the initial focus on saving life and after that the patients is worried about the aesthetic issues. The hands are often neglected in this scenario. No other postburn deformity gets worsened with time as hands do due to contracture of webs. So, after surgical correction of hand burns, exercise with web splints to fingers and wrist is advised.

The degree of contracture depends on the amount of skin loss due to deep burns, which heals by contraction. So, each patient should be treated with individual customised web splint design. The importance of physical therapy with web splints after surgical correction would be emphasised to improve hand function.

The web spacer designed here is very handy apparatus when dealing with thumb web contractures. It has been used for prevention, for correction in the early stages of contracture and for maintenance of correction following surgical release. Unlike previously described devices, the spacer holds the metacarpals and thus exerts more effective force, strong enough to maintain the thumb web in a functional position and can be applied when the hand is wounded. The most attractive feature is its ability to allow movement of the carpometacarpal and metacarpophalangeal joints. In addition to being patient and surgeon friendly, the splint is washable and has good patient compliance.

Learning points.

• The new and different types of thumb web splints are presented, based on the patient’s needs, which can be used for the prevention and treatment of thumb web contracture of various aetiologies.

• Successful postoperative care is equally important to maintain web space release.

• Placement of a thumb splint and patient complaints is important to maintain the web space during the interval healing period.

Ethics statements

Patient consent for publication

Consent obtained from parent(s)/guardian(s).