Effectiveness of a novel finger range-of-motion brace for extensor tendon injury: a report of 10 patients

Abstract

Background

Extensor tendon injuries require surgical repair, followed by rehabilitation to ensure optimal outcomes. Immobilization has been the cornerstone of postoperative management. However, immobilization after surgery frequently makes the finger stiffness, often resulting in reduced functionality and quality of life for patients. Recent studies indicate that early controlled motion can significantly improve outcomes, but safe early range of motion (ROM) exercise is a significant clinical challenge. This article aims to check the efficacy of the novel designed finger ROM brace for preventing finger stiffness for extensor tendon injuries with case series.

Methods

A finger ROM brace was designed based on the natural finger movement. Like a real finger, there are two tiny hinge joints and three round-shape body components. The design aimed to be ergonomic dynamic splint assisting controlled motion to promote early motion, thus reducing tendon tension and preventing stiffness. Elastic resistant ROM exercise could be by inserting a silicone band into the groove on the components and free movement could be achieved by removing a silicone band.

Result

Between December 2022 and July 2023, 10 patients who underwent tenorrhaphy because of extensor tendon laceration were involved. Complete extensor tendon laceration was 3 patients, other seven patients had partial laceration of extensor tendons. Surgery was performed within 2 days of injury, and no infection was observed in all patients. After the extensor tendon was confirmed as healed state by ultrasound, the patients were permit the active exercise wearing finger ROM brace with a silicone band. Within 1–2 weeks after elastic resistant exercise, the patients could achieve free full ROM movement without any complication.

Conclusion

The novel finger ROM brace combines the advantages of dynamic splinting and under-actuated mechanisms to offer a comprehensive solution for preventing stiffness after extensor tendon suture. Future studies should focus on clinical trials to validate the efficacy and safety of this brace in a larger population.

Background

Finger stiffness is the most common and disturbing problem after hand tendon injury. This stiffness is caused by healing process and immobilization. After tendon injury, vasoactive and chemotactic factors are produced by injured parenchymal cells and the activated coagulation and complement pathways [1]. While inflammatory cascade, protein-rich exudate leaks out into the interstitial space, but can’t back out to lymphatics, resulting in edema [2, 3]. This extracellular exudate contributes to finger stiffness through an increased resistance to movement, joint capsular distention, and swelling of the capsule and ligaments [4]. In addition, immobilization itself after trauma accelerates the finger stiffness worse. The chemotactic factors gather inflammatory leukocytes such as monocytes, neutrophils and macrophages to the injured site. These leukocytes remove debris and necrotic tissue and secrete matrix metalloproteinase including collagenase, resulting scar formation [5].

Many hand surgeons want to prevent stiff fingers by using aggressive rehabilitation and multiple kinds of dynamic splints. The basic principle of early rehabilitation for extensor tendon injury is gliding of the tendon with no exceeding force to occur re-rupture [6, 7]. Moreover, this exercise promotes healing of the repair site and improves the strength of injured site [8]. Among the methods known to date, the most effective is early active range-of-motion (ROM) exercise within safe range [9,10,11,12]. However, until now, there has been no convenient orthosis to help you do safe active ROM exercise.

We developed a novel finger ROM brace which is a small, lightweight, and patient-friendly orthosis [13]. With this orthosis, we would like to report the clinical results in zone II-IV extensor tendon injuries with literature review.

Method

Description of the orthosis

The finger ROM brace was first introduced as a preliminary study last year [13]. The proposed design aimed to integrate the most effective elements of existing devices and rehabilitation techniques. Therefore, we intended that the brace was applied for just injured fingers. The components of brace are three bodies and two hinges [Fig. 1]. The bodies were designed to wrap each phalanx to prevent rotation while exercise. There are two tiny hinges for connecting these bodies acting like interphalangeal joints. These hinges allow free ROM exercise but can’t restrict the range of motion due to so tiny part. There are slots for inserting accessories which control finger movement in the superior side of the bodies [Fig. 2]. The one is a straight bar which prevent movement and immobilize. The other is a silicone band which permit resistant elastic exercise, not allowing full flexion. This silicone band is the key accessory for controlled active movement to avoid excess tensile force on suture site and reduce the risk of re-rupture. Unlike other fingers, the thumb has only two phalanges and is thicker, so the brace for the thumb was made separately [Fig. 3].

Fig. 1

The overall appearance of the finger ROM brace. This orthosis composes of three bodies and two tiny hinges. The hinges and the shape of the body allow for extension (A) and flexion (B) freely

Fig. 2

There are two kinds of the accessories for control the movement of finger. One is a straight bar which block the movement and immobilize the finger (A&B). The other is a silicone band which allow elastic resistant finger motion within limited range (C&D)

Fig. 3

Thumb has two phalanges even though other fingers have three phalanges, so the orthosis for thumb should be designed separately. Comparison from above (A) and from side (B)

Method to apply the brace

All cases were undergone tenorrhaphy under regional or local anesthesia. Until postoperative two weeks, we applied general finger splints for immobilization. At the postoperative second week, the skin sutures were removed, and then we checked the injured extensor tendons by ultrasound. Ultrasound is an easily accessible modality in evaluation of tendon healing after surgical repair [14]. If the tendon laceration was less than 50% of the width of extensor tendon and the there was no gap between the injured site, the finger ROM brace with a silicone band was applied and the patient started resistant active ROM exercise. If the tendon laceration was more than 50% or the gap between the injured site was seen, the finger brace with a straight bar was applied and one week later, the straight bar changed to a silicone band and resistant active ROM exercise started. After one week later, the silicone band was removed, and the patient was allowed for free ROM exercise. The patient took off the brace when they achieved the full ROM exercise. The angles of distal interphalangeal (DIP) joint, proximal interphalangeal (PIP) joint and metacarpophalangeal (MCP) joint were measured with a goniometer.

Results

Between December 2022 and July 2023, 10 patients who underwent tenorrhaphy because of extensor tendon laceration were involved. The average age of the patients was 53.8 ± 5.76 years, with females comprising 20% of the patients. Complete extensor tendon laceration was 3 patients, other seven patients had partial laceration of extensor tendons. Most injured fingers were thumbs and index fingers. Only 1 patient had less than 50% of the extensor tendon damage, and the remaining nine patients were all more than 50% [Table 1]. Surgery was performed within 2 days of injury, and no infection was observed in all patients.

Table 1 Demographic characteristics

Table 2 The measured angle of cases

All patients removed the skin sutures at the second week of surgery and checked the injured extensor tendons by ultrasound. Except the one patient who injured extensor tendon less than 50%, the remaining nine patients were confirmed by ultrasound, and the extensor tendons were still recovering, so the patients were applied the finger brace with a straight bar for a week. After a week, no one showed re-rupture or gap between the ruptured tendons by ultrasound, and they immediately started finger ROM exercise using a finger ROM brace with the silicone band. All patients finally achieved full ROM within 3–4 weeks applying the finger ROM brace without re-rupture of sutured site [Table 2]. There was no re-rupture, stiffness or any complication pain after 1 year of surgery.

Case 1

A 57-year-old female patient visited the outpatient clinic because her left fifth finger was cut by a knife while cooking. Under the diagnosis of a partial laceration of about 70% of the extensor tendon, she underwent an emergency tenorrhaphy. Two weeks after tenorrhaphy, the stitches of the skin were removed, and then the status of sutured extensor tendon was checked by ultrasound. The tendon was still in recovery, so the patient wore a finger brace with a straight bar for a week. On the postoperative third week, the extensor tendon was checked again by ultrasound, and the continuity of the tendon was confirmed, so it was judged to be well healed. A silicone band was applied instead of the straight bar to commence active finger ROM exercises. One week later, the patient regained full freedom of finger movement without the silicone band [Fig. 4].

Fig. 4

Clinical photo of a 57-year-old female patient who wore the finger ROM brace with a silicone band on the postoperative third week (A). After 4 weeks after surgery, she applied the finger orthosis without the silicone band and was permit to start free exercise (B). Finally, she could achieve free ROM exercise on the postoperative fifth week (C)

Case 2

A 53-year-old male patient visited the emergency room after injuring his left thumb while cutting papers with a knife. He underwent tenorrhaphy due to partial laceration of about 50% of the extensor tendon of the left thumb. As in the previous patient, skin sutures were removed at postoperative 2 weeks and the surgical site was checked by ultrasound. The continuity of the tendon was some unclear, so the patient wore the finger ROM brace with a straight bar. After a week, the continuity of tendon was confirmed and he was permitted limited active finger ROM exercise changing a silicone band instead of a straight bar. Finally, he could regain full ROM movement without the silicone band [Fig. 5].

Fig. 5

A 53-year-old male patient underwent tenorrhaphy due to partial laceration of extensor tendon in left thumb. After 4 weeks after surgery, he could extend (A) and flex (B) his thumb freely with the finger ROM brace

Discussion

Extensor tendons are susceptible to damage because of their relatively thin, soft tissue coverage [15]. However, the extensor tendon injuries have received less attention rather than flexor tendon injuries concerning suture technique and postoperative rehabilitation. After the study which showed that extensor tendon injury affected not only fingers extension lose, but also great part flexion lose [16], extensor tendon injury was emphasized that loss of digital flexion could affect finger grasping and grip power.

The stiff finger or finger stiffness refers to a reduction in the ROM in the fingers. Prevention of a stiff finger is based on the principle of early joint motion [17]. Therefore, treatment of original diseases and injuries of hands should reduce the duration of immobilization so that finger stiffness can be prevented. In the past, conservative treatment was recommended for less than 50% of extensor tendon injuries and surgical repair was recommended if the injury was more than 50% [18, 19]. For the patients who got surgical treatment, immobilization has been a fundamental aspect of postoperative management [19]. Recently, it is a trend to exercise as quickly as possible after tenorrhaphy even a small amount of acute extensor tendon laceration. Early physical therapy after tenorrhaphy improves the gliding function of the sutured tendons and increases tensile strength, resulting in functional improvement and early return to work [20].

Early exercise protocols using varying combinations of instruments such as blocking splint, dynamic splint or relative motion splint and rehabilitation programs have become accepted beneficial and shown clinically significant good result [21,22,23,24]. Also, early mobilization with short-term splinting of only injured fingers and leaving the uninjured fingers free to move reduce undue stiffness in other fingers and seems to improve overall hand function [25]. However, improving extension contractures through such methods can sometimes be inadequate, cumbersome, time consuming, complicated and expensive leading to residual functional impairments [10]. Early mobilization using these methods has therefore been a significant challenge.

Also, while the immediate controlled active motion (ICAM) technique using the Yoke splint has become more common for injuries proximal to zone V [26], no widely accepted method has been established for zones II-IV extensor tendon injuries. The finger ROM splint developed for this purpose may potentially address this issue. The authors wanted to develop a simple, easy to use, small, lightweight, and patient-friendly orthosis for early protected controlled self-rehabilitation. Just by inserting two kinds of the accessory or removing the accessory, movement such as immobilization, elastic movement and free ROM exercise could be easily controlled.

To prevent rotation while ROM exercise, the shape of body is like a cylinder shape to wrap the phalanx. This shape makes the patients feel safe and comfortable. Also, the key of this orthosis is for patients to rehabilitate and achieve the natural recovery of finger ROM by themselves. Finger joint stiffness was relieved using an elastic resistance exercise protocol in the early postoperative period [27]. The splint, which utilizes the elasticity of silicone to provide passive extension assistance, aims to facilitate early mobilization while supporting extension.

1 year follow-up results of the finger ROM brace indicate that the brace significantly reduced limited ROM, providing stable support for the extensor tendon injuries. The simple design of the orthosis allows for easy adjustment and personalized fitting, ensuring optimal positioning and alignment of the finger during the rehabilitation.

Although the results are encouraging, we acknowledge certain limitations, such as the relatively small sample size. Future clinical study should aim to conduct larger samples with multi-centers for various extensor tendon injury cases. Also, we didn’t check the clinical aspects such as pain using Visual Analog Scale, grip strength and so on. We will also focus on not only the finger ROM, but also the clinical aspects in a future study.

Conclusions

Early finger ROM exercise is important for preventing finger stiffness in finger trauma. Especially, safe and controlled movement is more important in extensor tendon injuries because extensor tendon is so thin and exposure to re-rupture. The finger ROM brace design aims to integrate the most effective elements of existing devices and rehabilitation techniques. Furthermore, the ergonomic design enhances patient comfort and adherence to the early self-rehabilitation program. This finger ROM orthosis could be a good option for rehabilitation after acute extensor tendon injuries.