INTRODUCTION — Soft tissue musculoskeletal disorders refer to nonsystemic, focal pathologic syndromes involving the periarticular tissues, including muscle, tendon, ligament, fascia, aponeurosis, retinaculum, bursa, and subcutaneous tissue. These disorders are extremely common.
Although soft tissue musculoskeletal disorders refer to nonarticular pain, patients often attribute their symptoms to nearby joints. Thus, when patients complain of hip pain, the cause is often not pain in the joint itself, but rather in the "hip region": the groin, buttock, upper lateral thigh, greater trochanteric area, and iliac crest. Similarly, complaints of elbow, wrist, knee, and shoulder pain frequently mean pain in the general region of those joints, and may reflect soft tissue conditions such as epicondylitis, tenosynovitis, and bursitis.
Soft tissue disorders may be divided into several broad categories and include:
●Tendinitis
●Enthesitis
●Fasciitis
●Bursitis
●Structural disorders
●Neurovascular entrapment disorders
●Complex regional pain syndromes (CRPS)
●Myofascial pain syndrome
●Generalized pain disorders
Many of these disorders occur in the absence of systemic disease, and some are a consequence of chronic repetitive low-grade trauma and overuse. Many are self-limiting and respond to conservative measures.
This topic will provide a brief overview of the soft tissue rheumatic disorders. A general discussion on the approach to the patient with these disorders is also included. More detailed discussions of these disorders are presented separately. (See appropriate topic reviews.)
SPECIFIC SYNDROMES
Tendinitis — Tendinitis (or tendonitis) is a clinical and pathologic disorder with common features of local pain and dysfunction, inflammation, and degeneration. Tendinitis often results from overuse or a sports injury but may also be due to inflammatory rheumatic diseases or metabolic disturbances such as calcium apatite deposition. Tendinitis and tendon rupture have also been associated with the use of fluoroquinolone antibiotics and statins [1-3].
Tendinitis, tendinosis, and tendinopathy are some of the terms used to characterize acute or chronic tendon pain. The term tendinitis can be confusing because inflammation is often not seen on histopathology, and the other terms may be more appropriate. For the purposes of this discussion, we will use the common term tendinitis. A more detailed discussion on terminology is included elsewhere. (See "Overview of overuse (persistent) tendinopathy", section on 'Pathology and terminology'.)
Common sites of tendinitis include supraspinatus tendinitis of the shoulder (rotator cuff tendinopathy), lateral and medial epicondylitis (tennis and golfer's elbow), bicipital tendinitis, gluteus medius/minimus tendinopathy, Achilles tendinopathy, and flexor carpi radialis and flexor carpi ulnaris tendinitis. (See "Rotator cuff tendinopathy" and "Elbow tendinopathy (tennis and golf elbow)" and "Biceps tendinopathy and tendon rupture" and "Achilles tendinopathy and tendon rupture".)
Enthesitis — The enthesis is the site of insertion of ligaments, tendons, joint capsules, and fascia to bone (figure 1). These areas are highly vascular and are susceptible to bacterial and antigen deposition [4]. Enthesitis is often seen in spondyloarthropathies; common sites are the insertion of the plantar fascia and the Achilles tendon region (see "Clinical manifestations and diagnosis of peripheral spondyloarthritis in adults", section on 'Musculoskeletal features'). Ultrasonography is helpful for delineation [5,6]. (See "Musculoskeletal ultrasonography: Clinical applications", section on 'Enthesitis'.)
Fasciitis — Fasciitis includes Dupuytren's palmar contracture, fascia lata fasciitis, and plantar fasciitis. They have discrete and disparate pathologies which include proliferation and degeneration of fascia. These disorders are discussed in more detail separately, as are other forms of fasciitis that have more systemic involvement, including necrotizing fasciitis and eosinophilic fasciitis (see "Dupuytren's contracture" and "Approach to the adult with unspecified hip pain" and "Plantar fasciitis" and "Necrotizing soft tissue infections" and "Eosinophilic fasciitis"). Magnetic resonance imaging (MRI) is often useful in identifying these conditions.
Bursitis — Bursitis is inflammation of the small fluid-filled pads, called bursae, that act as cushions between the bones and adjacent tendons and muscles, protecting the soft tissues from underlying bony prominences. Bursitis may result from direct trauma, repetitive injury, or infection, or it may be a manifestation of a systemic disease such as rheumatoid arthritis or gout. A diagnosis of bursitis is based on the findings of exquisite local tenderness at bursal sites, pain on motion and at rest, and sometimes associated regional loss of active movement. Swelling may be evident when bursitis occurs close to the body surface (eg, bunion or prepatellar bursitis) [7]. (See "Bursitis: An overview of clinical manifestations, diagnosis, and management".)
Structural disorders — Musculoskeletal structural disorders are relatively common. In healthy young adults, for example, one study found that a total of 158 separate congenital, developmental, and acquired abnormalities were detected in 73 percent of 127 medical students [8]. Findings included decreased joint range of motion and articular laxity, as well as synovitis, tendinitis, and bursitis. Participants in contact sports had the highest prevalence. (See "Clinical manifestations and diagnosis of hypermobile Ehlers-Danlos syndrome and hypermobility spectrum disorder", section on 'Epidemiology'.)
Subtle disorders often contribute significantly to pain syndromes in the lower extremity. "Miserable malalignment syndrome" is a term used to describe a combination of malalignments of the leg that include excess femoral anteversion with internal rotation of the hip, genu valgus, squinting patellae, external tibial torsion, and flat feet. Affected individuals are predisposed to overuse injuries and are often advised to avoid sports such as long-distance running. Structural disorders frequently contribute to injury in sports participants. (See "Overview of running injuries of the lower extremity".)
Body asymmetry is a common cause of many regional pain disorders. When one side of the face is smaller, for example, temporomandibular joint dysfunction is more common (picture 1). The rest of the ipsilateral body may also be small in such patients, sometimes resulting in a scapulothoracic syndrome related to scoliosis or back pain in association with a short leg or an underdeveloped buttock.
Neurovascular entrapment — Neurovascular entrapment disorders may occur within the spinal canal (lateral recess or central spinal stenosis) or nerve root (foraminal stenosis), or along the course of a peripheral nerve. The peripheral sites most commonly affected are compression of the median nerve at the wrist (carpal tunnel syndrome), compression of the ulnar nerve at the cubital tunnel, and compression of the tibial nerve at the tarsal tunnel. Less commonly, the lateral femoral cutaneous nerve is entrapped under the inguinal ligament (meralgia paresthetica). (See "Overview of upper extremity peripheral nerve syndromes" and "Carpal tunnel syndrome: Clinical manifestations and diagnosis" and "Overview of lower extremity peripheral nerve syndromes" and "Meralgia paresthetica (lateral femoral cutaneous nerve entrapment)".)
The diagnostic triad of peripheral neurovascular entrapment includes:
●A sensation of swelling and pain in the involved region
●Paresthesias and/or numbness distal to the site of entrapment
●Muscle weakness (ie, loss of hand dexterity) in advanced cases
Tapping over an involved peripheral nerve (eg, Tinel sign in carpal tunnel syndrome) or compression with an inflated blood pressure cuff proximal to the nerve may produce a sensation of electric shock and therefore aid in the diagnosis.
Complex regional pain syndromes — The complex regional pain syndrome (CRPS) may be related to nerve injury, other trauma, surgery, or a vascular event such as myocardial infarction or stroke, or there may be no obvious triggering event. Alternative names include reflex sympathetic dystrophy (RSD), algodystrophy, causalgia, and shoulder-hand syndrome. It was renamed by a consensus development conference in 1995 as CRPS [9]. It is usually characterized clinically by exquisite burning pain, edema, allodynia, hyperpathia, abnormal sudomotor activity, and hyperesthesia in the limb, which may feel cold or hot and may change color, and by local bone demineralization.
Two types of CRPS have been recognized:
●CRPS type I (formerly termed RSD) – Refers to patients without a definable nerve lesion
●CRPS type II (formerly termed causalgia) – Refers to patients with a definable nerve lesion
The causes, clinical features, diagnosis, prevention, and treatment of CRPS (RSD and causalgia) are presented separately. (See "Complex regional pain syndrome in adults: Pathogenesis, clinical manifestations, and diagnosis" and "Complex regional pain syndrome in adults: Treatment, prognosis, and prevention".)
Myofascial pain syndrome — Myofascial pain syndrome (MPS) is a regional pain disorder caused by the presence of trigger points within muscles or their fascia (figure 2) [10,11]. It has been described as "hyperirritable spots, usually within a taut band of skeletal muscle or in the muscle's fascia that is painful on compression and can give rise to characteristic referred pain, tenderness, and autonomic phenomena" [12]. MPS shares some features with fibromyalgia, which are discussed separately (table 1). (See "Differential diagnosis of fibromyalgia", section on 'Myofascial pain syndromes'.)
MPS is a relatively common source of chronic pain in the general population. The lack of universally accepted diagnostic criteria has resulted in variable estimates from epidemiologic studies, and most of the available data pertain to musculoskeletal pain in general. One study that estimated the prevalence of myofascial pain in a general internal medicine practice found that the primary complaint of 30 percent of patients was due to myofascial pain [13].
The pain of MPS is of a deep aching quality, occasionally accompanied by a sensation of burning or stinging. The pain often occurs in just one anatomic region, and patients often complain of restricted active movement in that area.
Myofascial trigger points (MTP) are the characteristic findings on physical exam. One or more trigger (pain) points will be found if the examiner gains familiarity with the likely point locations for each body region (figure 3A-B). Trigger points often feel indurated to palpation, and palpation reproduces the pain in the "target zone," often at some distance away. Trigger points may result from acute trauma, repeated minor microtrauma of daily living, or the chronic strain of sedentary work or living habits. Thus, evaluation of such patients with myofascial pain should include inquiry into activities and habits of movement. Patients with whiplash-associated myofascial pain have a higher prevalence of trigger points along the semispinalis capitis muscle than at other sites in the neck, jaw, and upper shoulder [14]. (See "Overview of joint protection".)
MPS may include other common regional pain disorders such as tension headaches, idiopathic low back and cervical strain disorders, repetitive strain syndromes, occupational overuse syndrome, cumulative trauma disorder, work-related musculoskeletal disorder, and temporomandibular joint (TMJ) syndrome [15-18]. In the head and neck, the pain may be associated with unexplained dizziness and with neurocognitive disturbances. The etiology of these complaints is not understood, although some neurovestibular abnormalities are often found in patients with TMJ and myofascial pain of the head. These poorly understood pain disorders are also associated with fatigue, sleep abnormalities, irritable bowel syndrome, and mood disturbances, which may also be observed with fibromyalgia (see "Clinical manifestations and diagnosis of fibromyalgia in adults", section on 'Symptoms'). Chronic, unexplained pelvic and urethral pain, sometimes termed the female urethral syndrome, is often considered to be a variation of myofascial pain.
Many clinicians are skeptical about the existence of trigger points. Confusion also arises when differentiating trigger points from the tender points of fibromyalgia. Fibromyalgia tender points are said to differ in that they typically are not indurated and occur in tissues other than muscle (table 1). However, some find little difference in the tender point and trigger point examination in patients with fibromyalgia and MPS. A number of reports have questioned the reliability of the tender point evaluation, and it has been eliminated from the 2010/2011 preliminary and revised American College of Rheumatology diagnostic criteria for fibromyalgia [19]. Interestingly, microdialysis studies comparing active versus latent trigger points showed biochemical differences with elevated levels of sensitizing substances within the former [20]. (See "Clinical manifestations and diagnosis of fibromyalgia in adults".)
Myofascial pain is generally treated similarly to fibromyalgia (see "Initial treatment of fibromyalgia in adults"). However, myofascial pain also responds well to local treatments such as application of a cold spray and passive stretch of the involved muscle. Trigger point injections, using dry needling, saline, or botulinum toxin, have been effective in clinical trials for the treatment of myofascial pain [16,17,21].
Generalized pain disorders — Generalized pain disorders include the hypermobility syndrome, fibromyalgia, and somatoform disorders. These disorders all may cause widespread pain and in some cases disability.
●The hypermobility syndrome results from loss of muscle tone in a person with joint laxity. Widespread arthralgias and a sensation of joint swelling (without objective physical signs of swelling) that lasts for hours rather than days are typical of this disorder. (See "Clinical manifestations and diagnosis of hypermobile Ehlers-Danlos syndrome and hypermobility spectrum disorder".)
●Fibromyalgia is a clinical syndrome marked by widespread pain, fatigue, and is often associated with a variety of other symptoms. There is often overlap of fibromyalgia with chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) (table 2). (See "Clinical manifestations and diagnosis of fibromyalgia in adults".)
GENERAL INITIAL APPROACH — Six points of management can often be initiated during the first visit in a patient with a suspected soft tissue rheumatic disorder, even before the results of appropriate laboratory or radiologic tests are available:
●Exclude systemic disease
●Eliminate aggravating factors
●Explain the illness
●Provide self-help strategies
●Provide pain relief
●Explain prognosis
Exclude systemic disease — Systemic rheumatic diseases such as rheumatoid arthritis and other disorders such as diabetes mellitus, thyroid dysfunction, occult neoplasm, and drug reactions should be considered and excluded, if possible, in patients presenting with a suspected soft tissue rheumatic disorder. Such concurrent disorders are common. In a classic study, nearly 300 patients with work-related carpal tunnel syndrome underwent a systematic search for concurrent medical diseases. One hundred and nine separate atraumatic illnesses (principally hypothyroidism, diabetes mellitus, and various arthropathies) capable of causing arm pain or carpal tunnel syndrome were diagnosed. Nearly 70 percent of these conditions would have been missed if only record reviews and patient histories had been utilized [22].
The extent of the work-up is dependent on the diagnosis. As an example, a patient with tendinitis or bursitis following a cumulative movement strain is not likely to benefit from radiologic or laboratory studies. By contrast, a patient presenting with enthesitis of the Achilles tendon and inflammatory back pain who is under the age of 40 may require additional studies to evaluate for the possibility of ankylosing spondylitis. (See "Diagnosis and differential diagnosis of axial spondyloarthritis (ankylosing spondylitis and nonradiographic axial spondyloarthritis) in adults" and "Diagnosis and differential diagnosis of rheumatoid arthritis".)
Treatment can, in many cases, be initiated prior to receiving the test results. Furthermore, plain film radiographs or other imaging studies can often be deferred until a later visit if they are not likely to change initial management.
Eliminate aggravating factors — Events and activities preceding the pain state must be reviewed in order to recognize aggravating activities that can cause recurrences. (See "Overview of joint protection".)
●Improper resting, sitting, or working positions are common precipitating factors.
●Strain resulting from job performance, a new hobby, or repetitive tiring tasks should be recognized and modified.
●Strain resulting from structural disorders (eg, flat feet or heavy pendulous breasts) can also be altered with appropriate instructions.
●Psychosocial factors that might influence outcome including mood disorders, chronic insomnia, poor nutrition, drug dependency, interpersonal relationships, and other stressors should be investigated.
Joint protection advice should be provided. Ergonomic assessment is indicated when symptoms are severe, significantly interfering with life, persistent, and unresponsive to treatment. (See "Overview of joint protection".)
Explain the illness — Patients are often reassured when they are told that they have a soft tissue rheumatic disorder rather than more serious illnesses such as systemic lupus erythematosus or rheumatoid arthritis. In addition, validation that their problem is "real" (eg, in patients with myofascial pain syndrome [MPS] or fibromyalgia) often relieves anxiety. (See "Initial treatment of fibromyalgia in adults".)
Explain self-help strategies — At-home physical therapy and exercises should be outlined on the first visit, if appropriate (see appropriate topic reviews for rehabilitation programs for the head and neck, upper limb, and lower limb). A good plan is to have the patient enroll in a program that combines an aerobic, strength training, and stretching program.
Pain relief — Pain may promote muscle spasm, leading to a vicious cycle of increased pain and spasm. In addition, the self-help therapy program is more effective and results are obtained more quickly when adequate pain relief is achieved.
Acute injuries should be treated with the RICE regimen:
●Rest
●Ice
●Compression of injured tissue
●Elevation
Despite the paucity of adequate controlled clinical studies, heat and cold modalities have been used for many years in the treatment of musculoskeletal disorders [23]. Heat can readily be applied by hot packs or hot water bottles and can increase the threshold for pain, produce analgesia by acting on free nerve endings, and decrease muscle spasm. A review of the effects of superficial heat on low back pain showed moderate evidence for heat therapy providing a small short-term reduction in pain and disability [24]. It is not at all clear that heat should be used to treat patients with inflammatory diseases. Heat is not indicated in acute arthritis, since it contributes to increased inflammation and pain, but may be helpful for some patients with moderate joint inflammation, where it may reduce pain and muscle spasm. Ice is sometimes useful to control pain and swelling because it induces vasoconstriction of superficial and intra-articular tissues, reduces local metabolism, and slows nerve conduction. It may be applied using cold packs, ice baths, and vapocoolant sprays [25].
In addition to the RICE regimen, other simple, frequently used measures include use of oral or topical nonsteroidal antiinflammatory drugs (NSAIDs), and other topical applications with agents such as lidocaine or capsaicin (table 3) [26,27].
If simple measures have not sufficed, injecting the affected area with a long-acting glucocorticoid-local anesthetic mixture can be effective in bursitis, tendinitis, or carpal tunnel syndrome. (See appropriate topic reviews for description of the injection technique in the different disorders.)
The use of diagnostic ultrasound has greatly improved our diagnostic accuracy and broadened our understanding of soft tissue rheumatic disorders, while also affording greater precision in defining sites to be injected with glucocorticoids [28-30].
Acupuncture is another method that is employed to relieve pain. Its clinical value varies and seems to be based on the condition being treated and the specific methodology employed. (See "Acupuncture".)
Since it is not at all clear that botulinum toxin injections are clearly superior to the injection of less costly agents, we do not recommend using botulinum toxin for tender or trigger point injections. Several studies suggest that botulinum toxin type A may provide pain relief in MPS [31-33], while others have found an analgesic effect similar to injection of glucocorticoids [33] or saline [34] and less than or similar to that of lidocaine [35,36]. (See "Approach to the management of chronic non-cancer pain in adults".)
Explain prognosis — Most soft tissue rheumatic pain disorders are of short duration and the time until improvement becomes evident can be projected. Relief from carpal tunnel syndrome, bursitis, or tendinitis may require only a few days, while symptoms due to hypermobility syndrome or disorders of other structural deficits may require several months before moderate or great improvement is seen.
The expected clinical course should be explained to the patient at the initial visit if possible. Patients should also understand that this course is dependent upon the performance of the self-help program, and that their response to the program may impact the diagnosis.
SUMMARY AND RECOMMENDATIONS
●Soft tissue musculoskeletal disorders refer to nonsystemic, focal pathologic syndromes involving the periarticular tissues, including muscle, tendon, ligament, fascia, aponeurosis, retinaculum, bursa, and subcutaneous tissue. These disorders are extremely common. (See 'Introduction' above.)
●Soft tissue disorders may be divided into several broad categories and include tendinitis, enthesitis, fasciitis, bursitis, structural disorders, neurovascular entrapment disorders, complex regional pain syndromes (CRPS), and myofascial pain syndrome (MPS). Many of these disorders occur in the absence of systemic disease, and some are a consequence of chronic repetitive low grade trauma and overuse. Many are self-limiting and respond to conservative measures. (See 'Specific syndromes' above.)
•Tendinitis (or tendonitis), which often results from overuse, is a disorder with common features of local pain and dysfunction, inflammation, and degeneration.
•Enthesitis, which is an inflammation of the site of the insertion of the tendon to the bone, is often seen in spondyloarthropathies. Common sites are the insertion of the plantar fascia and the Achilles tendon region. (See 'Enthesitis' above.)
•Bursitis is inflammation of the small fluid-filled pads, called bursae, which provide a cushion between bones and tendons and/or muscles around a joint. Bursitis may result from direct trauma or repetitive injury, infection, or it may be a manifestation of a systemic disease such as rheumatoid arthritis or gout. (See 'Bursitis' above and "Bursitis: An overview of clinical manifestations, diagnosis, and management".)
•Musculoskeletal structural disorders are relatively common, sometimes subtle, and often contribute to pain syndromes and to injury in sports participants. Body asymmetry is a common cause for many regional pain disorders. (See 'Structural disorders' above.)
•Neurovascular entrapment disorders may occur within the spinal canal (foraminal or central spinal stenosis) or along the course of a peripheral nerve. The diagnostic triad of peripheral neurovascular entrapment includes a sensation of swelling and pain in the involved region, paresthesias distal to the site of entrapment, and weakness. (See 'Neurovascular entrapment' above.)
•A diagnosis of CRPS requires the presence of regional pain and sensory changes usually following a noxious event, often far from the involved site. The pain is of a severity greater than that expected from the inciting injury and is associated with characteristic clinical findings. (See 'Complex regional pain syndromes' above and "Complex regional pain syndrome in adults: Pathogenesis, clinical manifestations, and diagnosis" and "Complex regional pain syndrome in adults: Treatment, prognosis, and prevention".)
•In MPS, hyperirritable spots, often in just one body region, usually within a taut band of skeletal muscle or in the muscle's fascia, can give rise to characteristic referred pain. There are usually one or more trigger (pain) points; these are typically indurated and painful on compression. Myofascial trigger points may result from acute trauma, repeated minor microtrauma of daily living, or from a chronic strain of sedentary work or living habits. (See 'Myofascial pain syndrome' above and "Differential diagnosis of fibromyalgia", section on 'Myofascial pain syndromes'.)
●Six points of management can often be initiated during the first visit in a patient with a suspected soft tissue rheumatic disorder, even before the results of appropriate laboratory or radiologic tests are available. These are excluding systemic disease, eliminating aggravating factors, explaining the illness, explaining self-help strategies, providing pain relief, and explaining the prognosis. (See 'General initial approach' above.)
