Injuries to the upper extremity joints often result in joint stiffness. This is a common finding and can have a significant effect on the patient's quality of life and occupational capacity. Data from the National Electronic Injury Surveillance System in the US found an incidence of 1130 upper extremity injuries per 100,000 people [1]. The elbow is especially prone to become stiff, with incidence of nearly 5% [2]. Kong et al., in a recent retrospective study, found an incidence of 35.3% of radiocarpal stiffness after distal radius volar plating. The stiffness is often a result of soft tissue contracture, including the skin, musculature and surrounding joint capsule and ligaments [3].

Other contributing factors include genetic predisposition and prolonged immobilization [4]. Additional extrinsic and intrinsic factors may include heterotopic ossification and intra-articular cartilage damage, respectively [5]. Treatment for upper extremity stiffness usually begins with occupational or physical therapy. This non-operative treatment should be considered in mild contracture of short duration, usually 6 months or less [6], [7], [8]. The goal of therapy is to reduce the stiffness in the affected joint and regain a functional range of motion (ROM).

There are two main types of splint for improving motion: dynamic splints and static progressive splints (SPS) [9], [10], [11]. Until recently in Israel, the only available static progressive splints were those custom-made by the therapist using the turnbuckle design. The senior author (GZ), who had practiced in the USA, had years of experience in using the JAS splint (Joint Active Systems, Inc., Effingham, IL, USA) and found it to be effective even after other methods had failed. The hypothesis of this study was therefore that the JAS SPS splint is effective in improving motion after progress plateaued in therapy even after a trial of other conservative methods.

In addition to the patient-friendly protocol, the JAS splint has some unique features. Its mechanism of action utilizes a distraction force applied on the soft tissue around the joint, so that the force is focused not on but around the stiff joint, thus reducing pain when wearing the splint. Other splinting devices such as the turnbuckle device or other dynamic splints apply a constant compressive force on the joint, which makes the treatment more painful and less acceptable for the patient. Another important feature of the JAS splint is its ability to act on both flexion and extension by a simple adjustment which the patient can easily make after a short demonstration by the physical therapist.

Many studies addressed the question of which splint is preferable for a stiff joint, including several comparative studies. Some included the JAS splint [10], [11]. However, all of those including the JAS splint as SPS concerned first-line treatment method or after failed physical therapy.

We decided to conduct the present study for two main reasons. Firstly, the JAS protocol was initiated in our patients only after reaching a plateau in progression under other conservative methods, with progression falling short of functional ROM. These other methods comprised physical and/or occupational therapy, with or without other splinting devices.

Secondly, our working hypothesis is that the unique characteristics of the JAS splint improve stiffness even when dynamic splints or other conservative methods failed to do so.

We aimed to show that the JAS splint is effective, and can succeed where other methods failed.