Comorbidities Associated with Increased Prevalence of Musculoskeletal Dysfunction

The vast majority of clients who present for treatment in a hand clinic do not have only a hand injury. The therapist must be aware of the client’s comorbidities and provide comprehensive treatment that addresses the client as a whole, rather than just an extremity. Some of the more common diseases that are associated with lowered tolerance of the musculoskeletal system are diabetes, hypothyroidism/hyperthyroidism, gastric ulcer, chronic/recurrent infections, colitis, and cardiovascular and respiratory diseases.

Diabetes causes the production and use of insulin in the body to be impaired. This results in an abundance of sugar in the bloodstream. With diabetes, the pancreas secretes little or no insulin (type I diabetes) or the body becomes resistant to the action of insulin (type II diabetes). If the disease is not treated, the level of sugar in the bloodstream builds up and leads to diabetic complications.

The thyroid gland affects all aspects of metabolism. The thyroid releases hormones that regulate heart rate, the strength of bones, how quickly calories are burned, and sensitivity to heat/cold. If the thyroid gland is underactive or overactive (hypothyroidism/hyperthyroidism), medical treatment is necessary to avoid complications.²

A gastric ulcer is an open sore that develops in the lining of the stomach. The ulcer may result from diet, stress, medication, or bacterial infection.

Infections can occur when the immune system is suppressed or comes in contact with an organism to which it does not have resistance. Bones and joints become susceptible to chronic infections that originate elsewhere in the body and are passed to them via the bloodstream.³

Colitis is a painful and debilitating chronic inflammation of the digestive tract.⁴ Symptoms include bloating, cramping, abdominal pain, and loss of appetite. Cardiovascular and respiratory disease includes any of a multitude of problems involving the heart, lungs, and blood vessels. Some of these disease processes are preventable and are acquired over a lifetime; others are congenital. Cardiovascular disease is more prevalent than all of the previously mentioned diseases combined.^5,6

Exercise Considerations

Always use caution and discretion when prescribing the intensity of exercise. A thorough evaluation provides the necessary information regarding cardiovascular compromise or risk factors, pulmonary disease, diabetes mellitus, hypertension, obesity, peripheral vascular disease, arthritis, and renal disease.⁵

Precaution. An exercise program may not be recommended for uncontrolled diabetes. A rigorous strengthening or aerobic exercise program, in this case, may cause a hyperglycemic effect because cellular absorption of glucose is restricted. Insulin-dependent diabetic clients may need to decrease insulin or increase carbohydrate intake when exercising. They should monitor their glucose more frequently when starting an exercise program. For this client population, the exercise should be dosed at a lower level of intensity and duration initially and should progress at a much slower rate.²

Exercise for Prevention/Treatment of Osteoporosis

Exercise can help prevent or slow down bone loss, improve posture, and increase overall fitness. For clients who are at risk of osteoporosis, a bone density test before beginning an exercise program is recommended. Box 4-3 lists factors to consider when selecting an exercise.⁷

Although walking is the best of all of the options listed in Box 4-3, those clients who are unable to tolerate walking because of comorbidities or advanced osteoporosis have other options. These options provide benefit by generating muscle tension, which provides needed stress to bone. To prevent injury to those with advanced osteoporosis, clients absolutely should avoid the exercises listed in Box 4-4.

Client Education for Osteoporosis

Education of the client on what impact osteoporosis will have on his or her life and what the client can do to prevent fractures or falls is important. Teach clients about proper body mechanics by demonstrating proper posture. When teaching lifting and carrying techniques, show the client how to hold loads close to the body. Explain that strengthening exercises improve balance and decrease the risk of falling. Address fall prevention. Wearing of proper shoes, removal of throw rugs, sufficient lighting, and use of handrails decrease the risk of a fall or fracture.

Precaution. Avoid forceful, unguarded motions, such as opening a stuck window or bending forward to lift a heavy object. Instead, teach clients how to squat when lifting.

Bone

Bone is the protective and supportive framework that has rigid and static, elastic and dynamic properties. The properties and geometry of bone can be altered in response to internal and external stress and also in response to mineral demands. Bone has plastic qualities; it absorbs and stores compressional forces and transmits tensile forces. Bone also has elastic qualities. Long bone can deform up to 5%. The ability of bone to deform decreases with age.

Bone is composed of approximately 5% water and approximately 70% minerals (calcium hydroxyapatite, phosphate, magnesium, sodium, potassium, and fluoride carbonate); approximately 20% organic compounds, mostly type I collagen; and approximately 5% noncollagenous proteins. Osteoblasts are the functional building blocks of the osteoid matrix; they are located only at the surface of bone tissue. Osteocytes are mature osteoblasts. Osteoclasts are responsible for bone dissolution and absorption. Bone homeostasis balances synthesis, dissolution, and absorption with the forces that are applied on the skeleton.⁹

Cartilage

Cartilage is a semirigid connective tissue that is less dense and more elastic than bone. The functional unit of cartilage is the chondrocyte. Chondroblasts are immature chondrocytes, and they produce the ground substance or extracellular matrix of cartilage. This extracellular matrix consists of glycosaminoglycans and type II collagen. Water composes 65% to 80% of articular cartilage. Like fibroblasts, chondroblasts synthesize collagen and glycosaminoglycans when stimulated by mechanical tension. Mature cartilage is avascular and lacks nerve supply. Cartilage gets nutrition through imbibition. The mechanical forces of motion stimulate imbibition and removal of waste products.

The three types of cartilage are the following:

The two primary functions of articular cartilage are to promote motion between two opposing bones with minimal friction and wear and to distribute the load applied to the joint surfaces over as great an area as possible.¹⁰

Bone

The optimal stimulus for osteoblastic production in the regeneration of bone is modified compression in the line of stress. Wolff’s law states that bone will change its internal architecture according to the forces placed upon it.

Precaution. Abnormal shear force may cause a pseudarthrosis.

Pseudarthrosis or “false joint” occurs at the site of nonunion. Osteophytes are bony outgrowths that develop as the body attempts to provide stability or to repair itself. Shearing force stimulates undifferentiated mesenchymal cells to produce cartilage, and a false joint may be created at the fracture site.⁹

Cartilage

The optimal stimulus in the regeneration of cartilage is intermittent compression/decompression with glide. Joint movement (shear) is necessary to distribute synovial fluid over the cartilaginous surface and provide oxygen and other necessary nutrients. Intermittent compression forces the extracellular fluid within the joint to be compressed into the cartilage matrix. With joint immobilization, an alteration in joint mechanics and a decrease in the normal contact areas of cartilage occur. This eventually leads to joint dysfunction, hypomobility or hypermobility, and muscle guarding.

Precaution. The body responds to the stresses placed upon it. With abnormal stresses, there will be dysfunctional remodeling. This manifests as joint degeneration, osteophytes, bone spurs, or pseudarthrosis.⁹

Golgi Tendon Organs

Golgi tendon organs (GTOs) are proprioceptors that are located in the tendon adjacent to the myotendinous junction. They are arranged in series with the extrafusal muscle fibers. They are sensitive to stretch but are activated most efficiently when the muscle shortens. The GTO transmits information regarding muscle tension as opposed to length. Neural input from the GTO causes an inhibition of muscle activation. This provides a protective mechanism to avoid development of excessive tension.¹¹

Joint Mechanoreceptors

Four types of mechanoreceptors are found in the synovial joint capsules. Mechanoreceptors have a significant effect on muscle tone and pain sensation locally and distally along segmental innervations. The number of mechanoreceptors decreases with age. By age 70 the total number of receptors has decreased by about 50%, depending on factors such as genetics and activity level.¹²

Type I mechanoreceptors are found in the superficial layers of the joint capsule between the collagen fibers. A large percentage of the type I mechanoreceptors is found in the joints of the neck, hip, and shoulder. They have a great effect on the coordination of the tonic muscle fibers. They are slow-adapting and inhibit pain. They fire during movement and for about 1 minute after movement stops. They provide postural and kinesthetic awareness (awareness of the position of the body or body part in space). They are active in the beginning and end-range of collagen tension.

Type II mechanoreceptors are found in deep layers of joint capsules. A high concentration of the type II mechanoreceptors is found in the joints of the lumbar spine, hand, foot, and temporomandibular joint. They are fast adapting and pain inhibiting. They fire during movement and continue to fire until about ½ second after movement stops. They do not respond to stretch but are activated in beginning and midrange of collagen tension. They have more effect on the phasic muscle fibers and kinesthesia.

Type III mechanoreceptors are located in the deep and superficial layers of the joint capsules and ligaments. They are slow adapting and inhibit muscle tone in response to stretch at the extreme end-range of tension. They provide kinesthetic information, but their role is less understood than the type I and II mechanoreceptors.

Type IV mechanoreceptors are located in joint capsules, blood vessels, articular fat pads, anterior dura mater, ligaments of the spine, and connective tissue. They are not found in muscle. They fire when excessive levels of tension are reached in the collagen, and they warn of tissue trauma. They function as pain-provoking, nonadapting, high-threshold receptors. They fire continuously until the injurious stimulus is removed. They are provoked by excessive stretch, inflammation, high temperature (38° C to 42° C or 100.4° F to 107.6° F), or respiratory and cardiovascular distress.¹²

Pain has been defined by the International Association for the Study of Pain as an unpleasant emotional disorder evoked by sufficient activity in the nociceptive system and associated with real or potential tissue damage.¹³ The irritation causing the pain may be due to immobilization, physical trauma, infection, or emotional tension.

Precaution. Pain is a protective mechanism. Pain is not a warning that something is about to go wrong; it has already gone wrong! Pain is the way the body alerts the brain that an irritation to the tissue has occurred. For this reason, one must remember to exercise within a pain-free range of motion. In this case, feeling bad is a good thing because it is how your body communicates. Listen to the body.

Phases and Time Frames of Healing

The initial response to a traumatic event is irritation. This lasts for 5 to 6 hours. Vasomotor constriction occurs in the first few seconds. An immediate release of chemical vasodilators occurs. These dilators are also transmitters for the nociceptive (pain) system. The vasodilation increases the hydrostatic pressure because of increased capillary permeability. Clinicians rarely can influence this phase because of its immediate occurrence.

The next stage of healing is the acute stage, which lasts for 1 to 3 days depending on the vascularity of the tissue. During this time frame, a migration of the larger cell bodies through the wall of the vessel occurs. Subsequently, blood flow increases to the area, increasing hydrostatic pressure and increasing bleeding. The large proteins leak out of the capillary, causing a shift in osmotic pressure with resultant pulling of fluid out of the capillary. Venous stasis occurs distal to the traumatized area, and edema results (see Chapter 3).

The third stage of healing is the subacute stage. The subacute stage begins with the settled stage, where muscle spasming occurs over the next 3 to 5 days. Bleeding is no longer present. Oxygen and macrophages are present. Walling off of the capillary occurs, which makes waste removal difficult. This leads to secondary healing or scarring. Externally applied heat in the settled stage promotes stasis and inflammatory exudates. The preferred method of heating tissue is internally. Initiating movement with low resistance exercise produces friction and naturally generates heat. This promotes increased blood flow.

The final stage is the chronic stage. Tissue becomes strongly chemical bonded (covalent bonds) and mature at 9 to 12 months. At this stage the tissue becomes nonelastic and cannot be deformed. Mature scar tissue may cause pain. Clinically, concentrate on increasing the tolerance of the tissue to tension about the scar by use of controlled stress through properly dosed exercises.

Tissue-specific exercise in the subacute stage provides the optimal stimulus for the removal of metabolites, which are products of metabolism, from the tissue. Muscle contraction is necessary to transport metabolites from the cell and provide oxygen/nutrition to the area. Increased vascularization accomplishes this goal. This is achieved through many repetitions of properly dosed exercise with minimal resistance while avoiding excessive tissue tension. In other words, the muscle contractions with proper exercise facilitate formation of capillaries, blood flow, and removal of metabolites.