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If a patient is limited to having only one type of pinch, lateral pinch is the most functional.
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Lateral pinch is so important that a referral to hand therapy is indicated solely to restore or maintain lateral pinch.
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The hands are hyperreactive to cold and often have difficulty accommodating heat. Assessing patients’ response to both cold and heat should be part of the skin and Raynaud’s assessment.
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Heat applications, especially in a dependent position, increase swelling. For this reason, whirlpool use and Fluidotherapy are contraindicated in patients with hand edema.
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Both water and dry heat have a drying effect on the skin. Consequently, to counteract deforming forces, therapy must focus on preserving MCP joint flexion, thumb carpometacarpal (CMC) joint abduction, and PIP extension.
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Splints frequently exacerbate Raynaud’s phenomenon. All splints must be carefully constructed and monitored to avoid pressure that impedes circulation.
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It is important that range of motion (ROM) exercises are focused on mobilizing soft tissue in all directions, not simply achieving increased ROM in a single plane.
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There are two major subtypes of adult systemic sclerosis (SSc): “limited cutaneous” and “diffuse cutaneous.” It is essential for clinicians to understand the clinical features of each subtype.
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Deformities occur because of fibrosis that cannot be controlled and because patients do not have an objective way to determine their maximal ROM daily, allowing them to lose a millimeter at a time without noticing.
Scleroderma is the umbrella term for a group of disorders that includes sclerosis of the skin as a predominant feature ( Box 112-1 ). SSc is a generalized disease that is often seen in rheumatic disease and hand clinics and can cause severe hand impairment. However, patients with this disorder, and some health professionals, prefer the term scleroderma because it is easier to say and understand. Consequently, this has become the common term for systemic sclerosis. This disorder used to be referred to as progressive , but this descriptor has been dropped because many patients stabilize at a certain level and their disease does not progress. There are two major subtypes of adult SSc, limited cutaneous and diffuse cutaneous . It is essential for clinicians to understand the clinical features of each subtype.
Generalized scleroderma (systemic sclerosis, SSc)
Diffuse scleroderma (acute and chronic) (dcSSc)
Limited scleroderma (lcSSc)
CREST syndrome (calcinosis, Raynaud’s phenomenon, esophageal hypomotility, sclerodactyly, telangiectasia)
Overlap or mixed connective tissue syndromes
Sclero-lupus
Sclerodermatomyositis
Scleromyxedema
Primary biliary cirrhosis
Sjögren’s syndrome
Localized scleroderma
Morphea
Linear
Scleroderma-like syndromes (diseases with skin changes resembling scleroderma)
Occupational
Associated with vinyl chloride
Associated with vibration (“jackhammer disease”)
Associated with silicosis
Fasciitis with eosinophilia
Scleredema of Buschke (often postinfectious)
Metabolic
Porphyria
Amyloid
Immunologic
Graft-versus-host reaction
Juvenile-onset diabetes mellitus (results in digital sclerosis and joint contractures)
Scleroderma-associated syndromes
Inherited
Werner’s syndrome
Phenylketonuria
Brandywine triracial isolate
Tumor-associated
Carcinoid syndrome
Bronchoalveolar carcinoma
Definition, Epidemiology, Pathogenesis, and Classification
SSc is a disorder of the small blood vessels and connective tissue characterized by degenerative and inflammatory changes that subsequently lead to intense fibrosis. This disorder is found across all racial groups and all ages. It affects women three to four times more often than men and African Americans slightly more than others. Peak onset in women is in the childbearing years. SSc is rare in children. It is more common to see localized or linear scleroderma in children. For treatment of children, see Kuchta et al.
The cause is not known, but a leading theory is that there is an early interaction between endothelial dysfunction and immune abnormalities that induces a T-cell immune response and release of endothelial cytotoxic factors. This results in injury to the endothelium and leads to intimal proliferation, vascular scarring, obliteration of the microvasculature, fibroblast activation, and ultimately fibrosis. These changes activate the T-cell response and perpetuate the cycle.
Limited Cutaneous Systemic Sclerosis
Systemic sclerosis has been classified into two distinct subsets. In limited cutaneous systemic sclerosis (lcSSc) the skin manifestations are limited to the distal extremities (distal to the elbows and knees) and face (the trunk is spared). The skin changes are stable or slowly progressive, and hand ROM may remain nearly normal. Raynaud’s phenomenon (RP) is present for a long period before skin thickening occurs. Patients with lcSSc are more prone to digital ulceration, ischemia, and gangrene. There is a prominence of digital telangiectasis (dilated capillaries) and subcutaneous calcinosis, although the latter may be microscopic or occur late; and the serum is positive for anticentromere antibody in 70% to 80% of patients. People with this subtype rarely develop myocardial or renal disease but are prone to late (after 10-plus years) appearance of visceral involvement, including primary pulmonary arterial hypertension, intestinal malabsorption, biliary cirrhosis, and Sjögren’s syndrome with vasculitis.
The major variant within lcSSc is the CREST syndrome, the acronym referring to the symptoms of calcinosis, RP, esophageal dysmotility, sclerodactyly (scleroderma of the digits), and telangiectasia. (Note that these symptoms occur in both lcSSc and diffuse SSc, but when they constitute the primary syndrome they are referred to as CREST . ) Another variant is overlap syndrome , in which lcSSc is present with lupus, dermatomyositis, rheumatoid arthritis, and Sjögren’s syndrome. These patients generally have a better prognosis and lower mortality as compared with patients with diffuse SSc.
Diffuse Cutaneous Systemic Sclerosis
The second subset of systemic sclerosis is diffuse cutaneous systemic sclerosis (dcSSc). In this disorder there is often rapid progression of skin thickening, beginning distally in the extremities (acral) and progressing proximally to include the trunk. RP occurs within 1 year of onset of skin changes. Tendon friction rubs are palpable, polyarthritis is common, and the serum is positive for antibody to Scl-70. These patients are at a higher risk for developing early and often severe visceral involvement, such as renal crisis, myocardial failure, interstitial lung disease, and gastrointestinal complications.
dcSSc produces the most severe hand deformities early in the disease course. Patients with lcSSc are more likely to develop vascular insufficiency, gangrene, autoamputation, or surgical amputation. Even though the name scleroderma refers to hard skin, in dcSSc the fibrosis affects all of the soft tissue: skin, fat, fascia, muscle, tendon sheath, ligament, and joint capsule.
Diagnostic Tests and Epidemiology
Although the cause is unknown and genetic predisposition is still uncertain, significant strides have been made in early detection and prediction of who will develop systemic sclerosis. Virtually all cases of diffuse cutaneous systemic sclerosis occur in adults who have biphasic, episodic RP. ( Biphasic means they have pallor or cyanosis as well as suffusion or erythema in response to cold.) There are two diagnostic procedures capable of predicting 95% of the people destined to develop SSc. These are nail fold capillary microscopy to detect characteristic capillary dilation or avascular areas in the nail fold, and serum antinuclear antibody determinations of anticentromere and antinucleolar antibodies. The presence of one or more “tendon friction rubs” is also a strong prognostic sign of dcSSc.
Worldwide, across all ethnic groups, RP ( biphasic ) affects 3% to 5% of the population. Of this group, 10% to 15% test positive for one or both of the aforementioned diagnostic procedures. This means that nearly all patients with the potential for severe sclerosis and organ failure can be detected before irreversible scarring occurs. When effective treatments are developed, early intervention and prevention will be possible.
Localized Form of Scleroderma
There is also a localized form of scleroderma in which fibrotic lesions occur in a single patch ( morphea ), multiple patches ( guttate morphea ), confluent patches ( generalized morphea ), or linear bands . There is no associated systemic or visceral involvement. It affects primarily children and young adults, mostly female. Morphea begins with an area of erythematous or violaceous discoloration of the skin, progressing to a waxy or ivory-colored sclerotic patch surrounded by an inflammatory border. The lesions often soften after a few months or years. New lesions usually stop after age 35.
In children the morphea affects all of the associated soft tissue and can retard bone growth. Linear scleroderma that crosses a joint may lead to a severe contracture and fibrotic distortion of the nearby neurovascular compartment. When this occurs in the hand, usually only one or two digits are involved. This form of scleroderma is very resistant to treatment. Hand therapy can be modeled on the program outlined in this chapter for dcSSc, except that the precautions for Raynaud’s phenomenon, swelling, associated conditions, and deformity patterns do not apply. Both localized and systemic scleroderma appear to have the same pathology and presentation in adults and children. Thus, hand therapy protocols are applicable to both groups.
Medical Management
There are three major components of SSc that can be addressed with medications: vascular damage (e.g., renal crisis, pulmonary arterial hypertension), immune cell activation , and fibrogenesis. The current medical philosophy in rheumatology is a combination strategy treating all three processes, as this is more likely to control the disease than single-agent therapy. In addition, most patients receive medications to manage associated symptoms such as gastroesophageal reflux disease, Raynaud’s phenomenon, and joint inflammation.
Vascular Damage
Until the 1990s renal disease was a major cause of death. The risk of renal damage from scleroderma renal crisis has been lessened by early detection, prompt initiation of angiotensin-converting enzyme inhibitor therapy, and avoidance of high-dose corticosteroids. This approach has improved the 9-year survival rate from 38% to 68%. Currently, lung disease and fibrosing alveolitis are the leading cause of death in SSc.
Endothelin-1 receptor blockers and phosphodiesterase-5 inhibitors have been effective for improving pulmonary arterial hypertension. Cyclophosphamide is now recommended for treating interstitial lung disease in SSc.
Immune Cell Activation
Cyclophosphamide (Cytoxan) has been proven an effective immunosupressive drug and is now considered a true “disease-modifying drug.” Autologous stem cell transplantation (following chemotherapy) is being tested in a prospective randomized controlled trial and is a possible option for very severely affected patients. It appears to “reset” autoimmunity in SSc. Tyndall and Furst report over one third of patients have experienced sustained remission. An analysis of hand function in five patients found that autologous stem cell transplantation improved hand function over 12 months and resolved refractory tenosynovitis, improved global hand function, and increased skin softening when the patient had disease remission. Both hand length (less contracture) and digit abduction improved. In this study loss of finger abduction was a more sensitive measure of finger clawing than loss of hand length.
Fibrogenesis
So far, strategies to reduce or control fibrosis directly (bosentan, interferon-γ, and relaxin) have been disappointing, but new strategies against fibrosis based on advanced understanding of the molecular biology of SSc hold promise and are under investigation, including Cellcept and anti-interleukin 13. Dr. Daniel Furst, a leading researcher in scleroderma, is currently using cyclophosphamide (Cytoxan) and methotrexate to control or reduce fibrosis.
Symptomatic Treatment
Medications (e.g., calcium channel blockers and angiotensin-II receptor blockers for RP, appropriate treatments for gastroesophageal reflux disease), antibiotics for malabsorption, anti-inflammatory drugs for arthritis, and lifestyle modifications can help prevent complications, such as digital ulcers and Barrett’s esophagus .
Prognosis is determined by the degree of internal organ involvement. Optimal patient care includes an integrated, multispecialty medical management to promptly and effectively recognize, evaluate, and manage complications and limit end-organ dysfunction.
Quality of Life and Hand Function
Comprehensive disability outcome assessments of patients with SSc have served to focus attention on physical and functional limitations that can impair quality of life. Therapeutic measures that can minimize patient functional impairment include preventing contractures of small and large joints, softening the skin, relieving joint pain and swelling, strengthening weak muscles, reducing fatigue and malaise associated with systemic inflammation, and management of ischemic hand ulcers (see “Associated Hand Conditions,” below). In particular, the striking effect of hand dysfunction, reflected by reduced ability to make a fist and reduced hand-spread, suggests that a major goal of treatment strategies in the future should be to lessen hand dysfunction.
Hand Involvement in Systemic Sclerosis
Early Signs and Symptoms
In the early stages, patients with lcSSc and dcSSc appear very similar, but with time those with dcSSc develop more severe limitations on the entire hand and patients with lcSSc often have limitations distal to the MCP joints. (The MCP joints are spared.) Typically, the first symptom the patient notices is swelling (nonpitting edema) and tightness in the hands, feet, and possibly the face. People with lcSSc have RP for years before symptoms appear. Those with dcSSc develop RP shortly before or within a year of onset of the skin changes.
Initially, some patients have no other symptoms beyond the swelling and feeling of tightness in their fingers (sclerodactyly or acrosclerosis). Others (usually patients with dcSSc) develop simultaneous onset of polyarthritis with associated malaise, joint pain, and fatigue. In the hand, joint swelling associated with arthritis may be masked by the diffuse edema, especially in dcSSc. The only obvious symptoms may be pain and aching in the joints and limited ROM (although the synovitis may be mild, it is a serious problem because it prevents ROM and increases the risk of contracture). Some people with dcSSc develop severe hand limitations in a matter of weeks, but others with lcSSc may maintain near full ROM for 10 to 20-plus years. Each case must be assessed and treated individually. Assessments that include questions about changes in hand mobility over the previous 1-month, 6-month, and 1-year periods are helpful for evaluating the progression and disease activity for rehabilitation purposes.
In very mild cases the skin can be the primary or only tissue involved. In most cases, however, ROM limitations result from fibrosis of all the soft tissues: skin, fascia, muscle, tendon, and joint capsule. Rheumatologists monitor skin changes in SSc using the Modified Rodnan Skin (thickness) Score: 0, normal skin; 1, mild; 2, moderate; 3, severe thickening. But in clinical practice it is helpful to understand the three stages of skin involvement: early, classic, and late, as defined by LeRoy. In the early stage ( Fig. 112-1 ) the hands, feet, and possibly the face are puffy, especially in the morning. This evolves into a taut nonpitting edema that fills the fingers, toes, and dorsal hand and foot skin. The epidermis and epidermal appendages (e.g., hair, nails, and sweat and mammary glands) remain intact. In the classic stage ( Fig. 112-2 ) the puffiness subsides and is replaced by tight, hidebound skin that feels dry and coarse and often itches. Areas of hypopigmentation or hyperpigmentation are common. The epidermis becomes thin and atrophic. Hair disappears or becomes coarser, and sweating is noticeably impaired. These changes are considered diagnostic. The late stage occurs 3 to 15 years after the beginning of the classic skin changes. The skin softens and becomes more pliable, but epidermal atrophy and loss of epidermal appendages remain. This may be part of a total remission or can occur while other symptoms (e.g., finger ulcers) continue to be active.
Deformity Patterns
Diffuse Cutaneous Systemic Sclerosis
Progressive fibrosis typically results in the following limitations: loss of MCP joint flexion, PIP joint extension, thumb abduction, opposition, flexion, and wrist motion in all planes. The distal interphalangeal (DIP) joints often are fixed in midrange flexion (the distal phalanx may be shortened from resorption). This typically results in a hand fixed in MCP joint extension, PIP joint flexion, thumb adduction, and wrist neutrality (see Fig. 112-2 ).
Consequently, to counteract deforming forces, therapy must focus on preserving MCP joint flexion, thumb carpometacarpal abduction, and PIP joint extension. From a functional standpoint, preserving lateral pinch is the most critical goal.
Thumb function represents about 45% of all hand function. As sclerosis progresses, tip-to-tip pinch then palmar pinch are lost. Lateral pinch, which is the last function lost, is the most important, because it is the power pinch. Loss of lateral pinch represents a tremendous loss of hand function, and its restoration either conservatively or surgically should be a prime goal in the treatment of SSc ( Fig. 112-3 ).
MCP joint flexion is lost as a result of several processes. First, the dorsal expansion is very delicate and vulnerable to fibrosis. Second, the lateral ligaments and dorsal capsule are in a shortened or lax position at rest (in other than full MCP joint flexion), putting them at risk of contracture. Third, the MCP joints are common sites for inflammatory arthritis in SSc, resulting in pain and swelling, which reduce the ability for flexion. Fourth, discomfort or pain in the hands resulting from RP, digital ulcers, and swelling may discourage use of the hands, resulting in decreased motion and diminished muscle-pump function for reducing swelling in the hands, especially around the MCP joints. Fifth, psychological depression, systemic illness, and fear of pain also contribute to diminished hand use and muscular guarding.
Limited Cutaneous Systemic Sclerosis
Patients may maintain full or near-full ROM for years with function limited more by ischemic fingertip ulcers, RP, and calcinosis than by deformity. The most common scenario is that sclerodactyly results in mild to moderate PIP joint flexion and extension contractures and stiff DIP joints in slight flexion. The MCP joints often have good mobility, but PIP joint flexion contractures encourage MCP joint extension, which can result in loss of MCP joint flexion. The primary therapeutic goal is to maintain PIP joint extension and MCP joint flexion and digit span. There is generally very little that can be done for the DIP joints. If therapy time is limited, the focus should be on maintaining MCP joint and thumb function because the PIP and DIP joints are limited more by vascular disease rather than soft tissue restriction. Maintaining thumb abduction is important. Lateral pinch is also important but is usually maintained naturally because MCP joint flexion is present.
Associated Hand Conditions
Raynaud’s Phenomenon *
* See Chapter 111 for medical management.
Raynaud’s phenomenon is defined as an episodic ischemia characterized by blanching (vasospasm), cyanosis, and suffusion or erythema as the blood returns. It occurs in 90% to 98% of people with SSc and is the first symptom in 70% of patients. It occurs in the hands, feet, nose, ears, and tip of the tongue. It is said to be elicited by cold or stress, but in SSc it may occur without any perceivable trigger. Continual ischemia is not considered RP, and uniphasic RP is not related to connective tissue disease.
Patients can use a range of behavioral methods to help control the symptoms of vasospasm. These constitute a patient education program for RP and are listed as instructions in Box 112-2 .
If you smoke or chew tobacco— stop! Nicotine narrows the blood vessels and reduces circulation.
Before going out in the cold, soak hands in warm or hot water (protect hands from drying effects of water by using a thin plastic glove) for 5 minutes.
Dress for warmth.
Keeping the trunk of your body warm helps increase the temperature of the arms and legs (e.g., wear a warm vest).
Layer clothes (e.g., wear an undershirt or camisole, two thin socks rather than one thick pair).
New lightweight, high-tech fabric clothes and undergarments specifically designed to retain heat are available in camping-goods stores or catalogues.
Wear hats and scarves outside in the cold to retain body heat.
Some patients wear inexpensive white cotton laboratory gloves at night or around the house to keep fingers warm.
Wear socks to bed.
Wear gloves to the grocery store, theater, mall, or other places with constant air conditioning.
Around the house:
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Use an electric blanket or sheet to warm the bed before getting in. If you do not like sleeping with an electric blanket, use it only to pre-warm the bed.
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Be careful to avoid becoming chilled while getting in and out of the tub or shower. Fluffy terry robes help.
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Eat modest meals; large meals decrease circulation in extremities.
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When traveling:
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On cold days have someone preheat the car before entering it.
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One patient reports carrying a small travel hair dryer to help warm her hands quickly when away from home.
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If possible, avoid medications that constrict blood vessels. These include certain migraine, heart, and blood pressure pills. Check with your pharmacist or doctor before taking any new drugs.
Factors that can trigger a Raynaud’s attack include a cold environment, touching something cold, air conditioning, drafts, nervousness or stress, and holding your hands down at your side for a prolonged period.
Goodfield et al. and Goodfield and Rowell conducted a controlled study evaluating the effect of hot water hand soaks every 4 hours during the day as a prophylactic treatment to improve blood flow. The patients alternated weeks of warming with nonwarming. The results showed a significant decrease in the number and duration of RP attacks during the “warming” weeks. Measuring blood flow through laser Doppler flowmetry, they found that patients have at least 2 hours of improved blood flow after the warming procedure. Goodfield applies this information clinically by having patients warm their hands before going out in the cold.
Thermal biofeedback can be another useful tool for selected patients. Secondary RP is more difficult to control with biofeedback than the primary form. It can be helpful, however, for patients disciplined enough to practice it and maintain the skills they are taught (see Chapter 109 ).
Digital Ischemic Ulcers
Digital ischemic ulcers have three typical forms of presentation. First, the most common are small ulcers over the fingertips or palmar surface, often the size of a pinhead or smaller. They are attributed to cutaneous ischemia and are very painful. Then, as the ulcer scars in, the ratio of viable tissue to the available blood supply comes into balance, the ulcer appears healed, and the pain stops. Unfortunately, new ulcers tend to appear; and patients usually have several at one time. Medically, these ulcers are considered a nuisance rather than a major concern. However, in hand therapy they can be a major problem, because they are painful and limit the patient’s ability to manipulate objects and perform daily activities. Having ulcers is like having multiple paper cuts on your fingertips. Determining the effect of these ulcers on function and the need for specific adaptive measures is therefore part of the hand assessment for these patients. The focus of treatment is to improve function by using adaptive equipment and techniques to reduce pain from ulcers during activities, and to reduce the symptoms of RP and muscular guarding elicited by the fear of hurting the hands during activities. Techniques include protective padding (e.g., self-adherent gauze wrap, e.g. Coban (3M, St. Paul, Minnesota), neoprene sleeve, gloves with only the essential finger sleeves, i.e., with the others cut off) over the ulcer, if possible, and adaptive padding of equipment and handles. When there are diffuse, multiple ulcers, wearing thin cotton laboratory gloves can help protect the hands and keep them warm.
The second type of digital ischemic ulcer is the ulcer that occurs over the dorsum of the PIP joints as a result of pressure from PIP joint flexion contractures, which tends to be larger and appears more like a classic ulcer. In the early stages it appears as a demarcated, tender area (see Fig. 112-2 ). It may remain like this for a long time or develop an open, necrotic center. Some ulcers stay open; others develop thick scabs. The PIP joints are prone to these ulcers, because they develop flexion contractures that stretch the taut skin over the dorsum of the joint (see Fig. 112-2 ). Active flexion reduces the blood supply to this area, as evidenced by dorsal blanching during grip, and impedes wound healing and closure. In addition, the dorsum of these joints is vulnerable to trauma during activities. These ulcers are a result of fibrosis and mechanical pressure as opposed to arterial occlusion or full digital ischemia.
The third form of ulcer is a classic ischemic ulcer that can occur on the sides of the hand or ends of the fingers as a result of a more generalized ischemia to the digit secondary to RP, fibrosis, or thrombosis of the digital arteries. Fortunately, these are less common than the first two types of ulcers. These ulcers can progress to frank gangrene. Often, the digit is allowed to autoamputate to preserve the maximal amount of digit length possible; otherwise surgical amputation is indicated.
For people with severe symptoms such as debilitating pain or ulcers or for those who are at risk for gangrene, medications can be helpful in controlling symptoms. These medications fall into two categories: those that prevent vascular spasm (e.g., prazosin, reserpine, guanethidine, methyldopa) and calcium channel blockers (e.g., nifedipine, diltiazem), which induce vasodilation. Medsger reports that nifedipine and prazosin have been the most successful in controlling symptoms and preventing the progression of ulcers. Ward and Van Moore report success in 40% of hands with nonhealing ulcers with a combined approach of cessation of all vasoconstricting agents, nifedipine, biofeedback, and local antibiotic ointment (silver sulfadiazine). Wrist blocks with lidocaine (Xylocaine) and bupivacaine (Marcaine) were offered if these modalities failed. If these methods did not result in healing of the ulcer within 12 weeks, digital sympathectomy was considered for the 60% who did not respond to nonoperative therapy. There has been one report of a placebo-controlled study of an oral prostacyclin analog, beraprost sodium, being effective in preventing ulcers and delaying onset of ulcers during winter, especially in lcSSc patients. Reduced nitric oxide levels have been proposed as a contributor to vascular disease in SSc. There are several case reports of patients with severe ulcers responding to oral sildenafil (Viagra), since it increases nitric oxide. Neil Jones et al. have developed an alternative approach to digital sympathectomy involving removing the adventitia (outer covering of the digital arteries). The adventitia is sympathetic-innervated. This procedure functions as a “decompression arteriolysis” to improve blood flow. He has also successfully used vein grafts to correct segmental arterial occlusions causing gangrene.
Often these ischemia medications are used after all behavioral methods (see Box 112-2 ) have failed, because they can cause serious cardiac, gastrointestinal, and psychological side effects and many patients cannot tolerate them. Some people need to take the medications only in the winter season.
For all open ulcers, meticulous wound and skin care is important. This includes keeping the wound clean, using antibacterial soap, avoiding exposure to dirt, and using antibiotic ointment as prescribed. These patients are vulnerable to developing staphylococcal infections that can progress to osteomyelitis quickly. All patients should be taught to recognize the signs of infection and to report them to their physicians promptly.
Telangiectasias
Telangiectasias are lesions formed by dilated capillaries that appear as dark red spots in the skin or just beneath the surface. They are commonly found in the face and hands and generally are not painful. However, those on the fingerpads may be tender to touch and need the same protection as palmar ulcers.
Calcium Deposits
Accumulation of calcium salts ( calcinosis cutis ) under the skin is a common symptom of this disorder. It is found in about 15% of patients with dcSSc and 44% of patients with lcSSc. In the hand, subcutaneous deposits tend to be localized ( circumscripta ) and may feel like a pebble or stone under the skin ( Fig. 112-4 ). (In the extremities, the deposit can form sheets of calcium under the skin, calcinosis universalis .) Generally, localized deposits are painless, but their hardness makes the skin and tissue over them sensitive to pressure. In the upper extremity, deposits tend to occur over functional pressure areas such as the volar aspect of the thumb interphalangeal joint, heel of the hand, lateral surface of the index finger, medial edge of the palm or ulna, and the elbow. Located in these areas, calcium deposits can significantly impair function.
