Although seemingly innocuous, fusion of the DIP joint can lead to the quadriga effect, a condition in which nonsurgical digits are unable to flex completely due to the lack of motion of the common flexor digitorum profundus muscle (Schreuders, 2012). As with the other methods of fusion, a client who undergoes DIP joint fusion is referred to therapy for motion exercise of noninvolved joints, edema control, and protective orthoses. Therapeutic intervention following joint arthrodesis Fusion also restores alignment of joints that are severely flexed or laterally bent—positions that lead to significant functional limitations in activities requiring fine motor skills. A joint undergoing fusion is typically immobilized in a postsurgical dressing for 10 to 14 days prior to referral to therapy. At that time, the therapist fabricates a finger-based orthosis to hold the joint in place while the fusion continues to heal. The client is instructed as needed in wound care and edema control techniques (Cannon, 2020). Edema control includes use of light compressive dressings such as gauze and Coban worn under the orthosis (Cannon, 2020). The orthoses are the same as those shown in Figures 13 and 14, and must be held securely in place to avoid displacement. Following surgery, the client is instructed to complete active and passive ROM exercises to joints surrounding the surgical joint that are stiff because of immobilization (Cannon, 2020). If pins are in place to secure the joint while the fusion solidifies, daily pin care using hydrogen peroxide (applied with a cotton swab) and antibiotic ointment can be instituted as prescribed by the surgeon. As the wound closes and the scar begins to mature, scar control using massage and silicone gel sheets can also be started 48 hours after suture removal to reduce sensitivity and improve appearance. Scar control through gentle cross-friction and circular massage assists with the reorganizing of collagen fibers of soft tissue to enhance suppleness and decrease adhesions that may contribute to pain. Massage with lotion should be conducted several times per day for about three minutes per session. Lotion or oil containing vitamin E is typically recommended for scars; however, no strong evidence exists for its use (Tanaydin et al., 2016). Silicone sheets and topical creams are meant to work by blocking moisture escaping from the skin. The buildup of pressure in the cells reduces the amount of oxygen supplied, and is thus believed to decrease the density of scar tissue. This popular method of scar reduction is supported anecdotally, but has minimal empirical evidence (O’Brien & Jones, 2013). At six weeks postsurgery and with approval from the surgeon, the fusion should be solid, and progressive strengthening can begin (Cannon, 2020). This is also the time to review occupational function with the client to ensure that they are able to engage in all desired daily activities.
Figure 17: Arthrodesis of Distal Interphalangeal Joint
Note: OA “X-ray of distal interphalangeal joint arthrodesis, left hand” by Jmarchn, used under Creative Commons license BY-SA 3.0. DIP joint arthrodesis Fusion of the DIP joint occurs similarly to the PIP joint and is typically the only viable solution to painful arthritis of this joint. Although DIP arthroplasty (i.e., replacement) procedures are possible, the DIP joints are typically unstable and become damaged easily (Rongières, 2013). Following surgical exposure of the joint using an H-shaped incision, the ligaments and terminal tendon are retracted and preserved. The DIP joint is taken apart and the joint surface is removed. The bone ends are made congruous (either flat or cup in cone) and set in a slightly flexed position (zero to 15 degrees). It is better to err on the side of too much extension than too much flexion with DIP joints. In addition, it is important to ensure that the joints align vertically without rotation. Although some surgeons prefer a type of fusion that is unfixed but allows for slight movement (i.e., intentional fibrous union), the thumb and index fingers require stable fusion with the joints in slight flexion to preserve fine pinch abilities (Rongières, 2013). As with PIP arthrodesis, the surgeon determines the method of fixation. K-wires, which are often used, are placed in longitudinal and oblique alignment to hold the joint secure. These are removed when the fusion has become solid. Other methods of fixation include tension wiring, headless screws, and specialized staples (Rongières, 2013).
THUMB CARPOMETACARPAL JOINT OSTEOARTHRITIS
Another condition commonly associated with OA of the wrist and hand is thumb CMC joint OA. An overview is provided, followed by discussion of conservative medical management, surgical management, and appropriate therapeutic interventions. The carpometacarpal (CMC) joint of the thumb is the second most likely joint of the hand to develop OA, with the proximal interphalangeal (PIP) joints the third. A client experiencing OA of the CMC thumb joint typically reports pinching and swelling at the base of the thumb just distal to the wrist. As the disease progresses, instability, impaired motion, and diminished strength are also reported and are increased significantly by repeated pinching, wringing motions, and grasping (Arthritis Foundation, n.d.). With radiographic examination, lesions most commonly observed in OA of the CMC joint are at the trapezio-metacarpal (TM) joint, but lesions can also be observed at other joints, including the trapezium and scaphoid. Radiographs for CMC
OA show typical narrowing of the joint with sclerotic changes, spur formation, and lateral subluxation of the base of the first metacarpal. Joint changes might have existed for a long period until an acute injury or repeated minor trauma occurred and irritated the joint tissues. As a result of the degree of pain experienced during strong pinching or abduction, a client typically avoids these motions and therefore experiences difficulty completing daily tasks. When limitation of motion at the TM joint occurs, compensatory movement takes place in the distal joint to give the thumb the necessary function. These compensatory movements eventually lead to thumb deformity. The two primary deformities of an arthritic thumb and fingers are the boutonniere and swan-neck deformities (Figure 18). Although these deformities occur rarely in OA of the fingers, CMC OA of the thumb leads to these patterns of deformity (Figure 19; Hauser et al.,2012).
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