Boutonniere deformity results from arthritic involvement of the metacarpophalangeal (MCP) joint, which becomes enlarged (Fig- ure 18). This enlarged joint causes elongation or erosion of the attachment of the extensor pollicis brevis muscle to the base of the proximal phalanx, leading to flexion deformity. As a result, the extensor pollicis longus tendon and adductor expansions become displaced ulnarly, and lateral thenar expansions are displaced ra- dially. This leads to further decreases in active MCP extension. When attempting extension of the MCP joint, there is hyperexten- sion of the interphalangeal joint, which eventually creates a pat- tern of function leading to joint contracture (Hauser et al., 2012; Figure 18). Swan-neck deformity occurs when the MCP joint is held in hyper- extension and the TM joint is forced into a subluxed position with the interphalangeal joint in flexion. If there is marked swelling of the CMC joint, the capsule becomes overstretched and the joint enlarges. This eventually leads to subluxation of the base of the metacarpal. With both boutonniere and swan-neck deformities, continuous avoidance of abduction secondary to pain gradually leads to development of an adduction contracture (Figure 18). A compensatory pattern of hyperextension of the thumb MCP fol- lows, called a Z-deformity (Badia, 2011). For ease of identification, all thumb deformities can be identi- fied using the Nalebuff classification system, which includes six deformities and their respective pathological mechanics (Hauser et al., 2012): ● Type I : Boutonniere with CMC unaffected; passively correct- able; MCP joint flexion and interphalangeal (IP) joint hyperex- tension. ● Type II : Boutonniere with CMC affected; adduction deformity. ● Type III : Swan-neck with MCP joint hyperextension and IP joint flexion. ● Type IV : Gamekeeper with injury to the ulnar collateral liga- ment. ● Type V : Swan-neck alone. ● Type VI : Skeletal collapse with bone loss; arthritis mutilans (i.e., severe derangement of the joints). cold modality, the therapy practitioner must remember that heat should not be applied if acute inflammation is present because the increase in local circulation could exacerbate swelling. As with ice treatments, heat should not be used with insensate hands. Immobilization of the CMC joint, allowing movement of the wrist and interphalangeal joint, can reduce and prevent pain. Rest dur- ing a painful exacerbation of symptoms reduces the duration of the painful event, reduces the possibility of further joint erosion, and maintains client function (Hochberg et al., 2012). Orthoses are available commercially, or the therapy practitioner can fabri- cate many styles. Factors such as severity of pain, demands of the task, severity of joint degeneration, and client preference affect the orthosis style decision. The orthoses described below are fab- ricated easily in the clinic and are comfortable for extended wear (Bielefeld & Neumann, 2011). The orthosis shown in Figure 20 is a hand-based thumb CMC sup- port orthosis that was fabricated from thermoplastic. The ortho- sis leaves the MCP, interphalangeal joint, and wrist free, which allows for maximum hand and thumb function. In severe cases, such support might be inadequate; a longer gutter extending into the forearm might be helpful, or a typical thumb spica orthosis extending from the radial to ulnar side of the hand might be indi- cated (Figure 21).
Figure 18: Swan-Neck Deformities of Fingers; Boutonniere and Adduction Contracture of Thumb
Note: “Swan neck deformity” by Phoenix 119, used under Creative Commons license BY-SA 3.0.
Figure 19: Mild Swan-Neck Deformity of the Thumb
Source: Erin Peterson
Conservative management Clients might first seek the advice of a physician when experienc- ing an acute exacerbation of the CMC OA that leads to pain and swelling. Pain might be brought on by pinching or gross use of the hand, and might be present at rest and when engaging in activity. Pain might come on suddenly due to engagement in a particularly stressful activity, or gradually when the thumb is used frequently with or without stress. Conservative medical treatment of CMC OA may include anti-in- flammatory medications, wear of orthoses, or corticosteroid injec- tions to aid in pain relief (Badia, 2011). It is prudent for the physi - cian to recommend therapy to provide any appropriate orthoses, education and adaptations to items used in daily life, education in joint protection techniques, and suggestions for home-based treatment methods such as paraffin baths and ice packs (Hunter & Lo, 2008). The physician also should explain to the client the pathophysiology of the disease, the likely sequelae of the condi- tion, and the potential for future invasive procedures such as joint replacement surgery. As with all forms of arthritis, the goals of treatment for those with CMC OA are typically reduction of pain, increased or mainte- nance of function, increased ROM and strength, and reduction of inflammation. Pain reduction can be accomplished in a number of ways, including use of the physical agent modalities (PAMs) in the form or heat or cold applications. When using any type of heat or
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