# Upper Limb Orthotics/Swan Neck Deformity
### Case study

    The patient is a 57 year old female. Retired nurse was diagnosed with RA (Rheumatoid Arthritis) at the age of 25. At that time, she was working as a nurse in a clinic of a primary school. They started with her the different medicines used with RA patients. During the first few years she wasn't regular on her medicine. After 10 years of diagnosis she started to notice her fingers to look strange and the doctor told her that she is developing a well-known deformity, that is Swan neck deformity. She was then referred to the orthotic department, were she was given a special made orthosis for her deformity. At first she was given a custom-made finger rings that she used for few days. However, due to pain and discomfort, she stopped wearing them few days later. Then she was given a prefabricated readymade finger rings. She used them for few weeks while working, but with these also she was feeling discomfort and pain while wearing them during work so she stopped using them.

### Evidence

    Swan neck deformity (SND) of the fingers is a well-known deformity seen mostly in Rheumatoid Arthritis’ patient and has been recognized clinically for perhaps 300 years ago (Dreyfus & Thomas, 1983). The term SND has only been used since 1957 introduced by Laine et. al. (Dreyfus & Thomas, 1983). It is also known as the deformity causing the hyperextension of the proximal interphalangeal joint with reciprocal flexion of metacarpophalangeal and distal interphalangeal joints (Heywood, 1979). There are various types of swan neck deformity. Although the pathological process may be the same, the swan neck deformities character may differ not only from patient to patient, but also from finger to finger in the same hand (Welsh & Hastings, 1977). Some reasons that can cause swan neck deformity: EHLERS-DANLOS Syndrome (Ercocen, Yenidunya, Yilmaz, & Ozbek, 1997), Rheumatoid Arthritis (Knight, 2006), Dislocation of a finger by AGEE Technique – as a complication of treating a fracture (Rawes & Oni, 1995), Contracture post injury to the volar aspect of the proximal interphalangeal flexion crease (Chinchalkar, Lanting & Ross, 2010), and Congenital swan neck deformity secondary to laxity of the palmar plate of the proximal interphalangeal joint (Ozturka, Zorb, Sengezera & Isik, 2005).
    The SND has a great impact on patients' functional ability to perform their daily tasks. It is important to gain a knowledgeable understanding of this deformity by understanding the structural and dynamic factors that constitute the normal muscle and tendon balance of the digits (Dreyfus & Thomas, 1983). They consist of 3 sets of muscles and tendons responsible for the equilibrium of the digits, and they are; the extrinsic extensor group, the extrinsic flexor group, and the intrinsic muscles (Dreyfus & Thomas, 1983). The extrinsic extensor group of muscles includes the extensor digitorum communis, extensor digiti minimi and the extensor indicis. These muscles originate in the dorsal forearm and insert via the common extensor tendons into the extensor hood and onto the dorsal surface of each digit. The sites of insertion are multiple and include the dorsal base of the proximal and middle phalanges as well as the distal phalanx via the lateral extensor tendons. The nerve supply is a branch of the radial nerve. The extensor muscles act via the extensor mechanism to extend the digits at the metacarpophalangeal (MCP) joint. In concert with the intrinsic muscles, they extend the proximal interphalangeal (PIP) and the distal interphalangeal DIP joints as well. The extrinsic flexor group includes the flexor digitorum profundus and superficialis (the deep and superficial flexors), originating in the volar forearm and inserting respectively into the bases of the distal and middle phalanges. The extrinsic flexors, supplied by branches of the median and ulnar nerves, flex the fingers at the PIP and DIP joints. Efficient MCP flexion requires the synergistic action of the intrinsic muscles.
    The intrinsic muscles (IM) include the four lumbricals and the seven volar and dorsal interossei. The lumbricals arise from the flexor tendons and insert into the lateral extensor bands. The interossei arise between the metacarpals and have various insertions in the MCP joint capsule and proximal phalangeal base, the extensor hood, and the medial and lateral extensor bands. The usual nerve supply of these muscles is the ulnar nerve with the exception of the first and second lumbricals, which are supplied by the median nerve. The intrinsic muscles act as a functional unit with two major effects: flexion of the MCP joints and extension of the PlP and DIP joints. By virtue of insertions into the base of the proximal phalanx volar to the axis of the MCP joint, the intrinsic muscles flex the MCP. The tendons then cross dorsally and join the extensor apparatus over the PIP and thereby act to extend the PIP and DIP (Dreyfus & Thomas, 1983).

### Orthotic treatment options

    The conventional technique used in the treatment of the different kinds of the swan neck deformity is Hand Orthosis. There are many types of these orthotic devices that result in different outcomes. Patients with swan neck deformity experience a lot of problems; the main ones are pain and limitation of functional daily activities. Either fixed or flexible, the swan neck deformity, may limit the ability to actively flex the PIP joint, with negative consequences for performing a pinch grip and grasping larger objects with one hand (Van der Giesen, Nelissen, Van Lankveld, Kremers-Selten, Peeters, Stern, Cessie & Vlieland, 2010). Studies on the effectiveness of the different types of splints used for swan neck deformity are little. There are 3 to 4 known types of the splints used for swan neck deformities. Silver ring splints, custom-made thermoplastic splints and prefabricated thermoplastic splints (Van der Giesen, Nelissen, Van Lankveld, Kremers-Selten, Peeters, Stern, Cessie & Vlieland, 2010). The main aim of using these splints is to prevent the deformity from becoming worse and to give the patient more functional use in his/her daily activities. All these splints are based on the same principle of using a three - point force around the PIP joint to prevent hyperextension at the PIP joint and subsequent DIP joint flexion- i.e. swan neck deformity (Adams, Hammond, Burridge & Cooper, 2005). Literature showed that several studies have been carried out to compare the effectiveness of the different types of the available splints. All these studies have shown the effectiveness of several types of the orthotic devices used by therapists in treating swan neck deformity.
    Knipping & Schegget (2000) compared the use and effects of custom- made versus prefabricated splints for swan neck deformities in Rheumatoid Arthritis patients on the variables cosmesis, comfort, functional use, and wearing time per 24 hours and effects on stability, grip strength and mobility. It was carried out on 18 patients 9 in each group. Each group used one of the splints for 3 months and another 3 months used the other splint. They concluded that the prefabricated splints are tolerated better and more acceptable in terms of wear than the custom- made splints. Zijlstra, Heijnsdijk-Rouwenhos, & Rasker (2004) studied the effect of Silver Ring Splints on hand function in patients with RA. They concluded that the Silver Ring splint could improve dexterity in patients with RA. In 2009, Van der Giesen, Nelissen, Van Lankveld, Kremers-Selten, Peeters, Stern, Cessie & Vlieland done a study on the effectiveness of silver ring splints with the commercial prefabricated thermoplastic splints in RA patients. They came to a conclusion that with RA patients with a mobile swan neck deformity the 2 kinds of splints are equally effective and acceptable. In 2010, Van der Giesen, Nelissen, Van Lankveld, Kremers-Selten, Peeters, Stern, Cessie & Vlieland done a qualitative study on patients' perspectives on hand function problems and finger splints to identify hand function problems and the reasons for choosing a specific finger splint in patients with RA and swan neck deformities to find that these 2 kinds of splints have the same effectiveness. In 2012, Elui, Rodrigues, Purquerio, Fortula & Fonseca presented the development of a splint with the original concept of blocking hyperextension of PIP joint in order to increase the functionality of the hand in carrying out daily activities. This splint defers from the old ones that the 2 separate parts joined with an axis of rotation allowing more function in the fingers. The study showed that this model has a satisfactory engagement with the finger, corrected the deformity and minimized the functional difficulties experienced by the patient daily.

### Comparison of Swan Neck deformity treatment options

    Despite the fact that swan neck deformity is usually treated with Hand Orthoses, a lot of different surgical procedures have been carried out in order to correct the swan neck deformity to increase functional daily activities levels. Cosmetic reasons have also been related to several surgical interventions. There are many surgical ways of treating SND, some of them are; distal joint infusion, dermadesis, flexor tendon tenodesis, retincular ligament reconstruction, intrinsic release, lateral band mobilization, skin release, arthodesis of the PIP joint, and arthroplasty with silicone rubber implants (Gainor & Hummel, 1985). A correction of the problem can also be by re-routing a lateral band of the extensor mechanism to prevent extension of the proximal PIP joint (Sirotakova, Figus, Jarrett, Mishra & Elliot, 2008). With many surgical ways of treatments to the deformity, Dreyfus & Thomas (1983) suggests that the key to the selection of the appropriate surgical treatment depends exclusively on identification of the pathogenetic mechanism.