The musculoskeletal system

The (neuro)musculoskeletal system comprises the bones of the skeleton, the joints at which movement occurs, the muscles that move them and the nerves that stimulate the muscles. The central nervous system (CNS) must also be included as it is the coordinator of all activity, for example that which occurs in the autonomic nerves to control the blood vessels essential for tissue nutrition, and that in the brain and spinal cord which controls the protective and coordinated movement patterns occurring in response to sensations arising from the periphery.

The skeletal and muscular systems are interconnected through joints and connective tissue. Dysfunction in one part will ultimately affect adjacent parts and may also have a broader effect through postural or gait adaptations. There are many factors that contribute to the original causative factor of musculoskeletal problems and, in some cases, one can lead to another. Those considered here are:

• Mechanical;

• Postural;

They are dealt with as mechanical and postural (including occupational factors, discussed in more detail in Chapter 14); disease; and trauma and surgical factors.

Mechanical and postural factors

The majority of patients with musculoskeletal problems who seek medical help have back or neck problems. Spinal problems and rheumatological conditions are thought to be much more common in the West than in countries where individuals lead a more active lifestyle. It is widely believed, therefore, that inactivity and resulting postural stresses, or sedentary or repetitive occupational stresses, are responsible for many of the symptoms. Generally, the human body must adjust in accordance with the person’s lifestyle. Individuals with physical limitations experience this in reverse: aspects of their lifestyle and behaviour may be dictated by their bodies to a greater extent. Lifestyle requires a particular excursion of joints and stretch of soft tissues unique to the individual, and specific activities will put physical structures through a wider range of movement more frequently. In an inactive person or someone whose job involves sitting, repetitive movements or inappropriate physical loading, plastic adaptation of a mechanical or postural nature must occur to accommodate this particular lifestyle.

The postural changes may be as a result of habit, for instance many hours over several years spent slumped in easy chairs, or sitting with rounded shoulders and a poking chin at a keyboard until, gradually, less muscular effort is made to maintain an upright posture against gravity (Figs. 12.1, 12.2). The postural (antigravity) muscles have a tendency to shorten (Janda 1983) and become structurally tight, and their antagonists tend to become reflexly inhibited and weakened. This produces postural changes and instability. A typical pattern is one of weakened, lengthened abdominal muscles and weak glutei. The hip flexors and the back extensors become short and tight. This was identified by Janda as the ‘crossed pattern’; it is accompanied by tight hamstring muscles, thought to be an attempt to stabilise the pelvis. The situation becomes more complicated where there are many short muscles together. The erector spinae, for example, although seen as one muscle mass running along either side of the spinal column, consists of three groups of muscles (iliocostalis, longissimus and spinalis), each of which has a subgroup in each area of the spine. The fibres of erector spinae run in several different directions over different distances. It is important that these muscles act in coordination, but imbalance can occur within the group. According to Janda, antagonist muscles tend to react in a way that is opposite to their agonist, either weakening or shortening, resulting in a muscular imbalance around a joint and eventually throughout the body.

Figure 12.1 • • Poor sitting posture.

Figure 12.2 • • Use of a lumbar roll to correct poor posture.

The muscles adapt to their shortening, probably losing sarcomeres (Williams & Goldspink 1978), and their connective tissue loses length and flexibility. As the reflex weakening of the antagonist occurs, these postural changes become self-perpetuating. They can be exacerbated, or indeed caused, by body language, whereby tall people may develop rounded shoulders, shy people a protective flexed posture in which the pectoral muscles become tight and the thoracic spine flexed and stiff, the chronically depressed a poking chin in which the extensor muscles of the neck become short (for further discussion see Kurtz & Prestera 1984). The normal mechanical stresses which the tissues experience through everyday functional activities are correspondingly altered and may be magnified as some (spinal) joints may now be held at an extreme of their range. The increased stress on the connective tissue causes remodelling and the fibres become laid down along the new lines of stress, so they actually change structure to accommodate the postures. Usual patterns of movement may start to strain this altered tissue. For example, sporting activities, or sudden explosive movements, such as running for a bus which places dynamic stretch on tissue, may strain or partially tear connective tissue. Adhesions or excess fibrous tissue may be laid down in response and attempts to correct the posture to a ‘normal’ one, or attempts at exercising to strengthen weakened antagonists, will produce pain. This is because ‘normal’ stress which protects joints has now become ‘abnormal’ as far as the collagenous tissues are concerned. Applying normal stress will in fact weaken the tissues as the fibres now lie in the direction of the abnormal stress and are therefore ill-equipped to resist normal stress. The obvious result of these attempts to correct the situation will be pain. This scenario was recognised by McKenzie (1981) in his postural syndrome (see Box 12.1). He recommends fully stretching ligaments and surrounding tissue following injury.

Box 12.1 • Postural syndrome

Characterised by pain that:

• Is alleviated by rest or lying down or by altering position;

• Is fairly localised (low back pain not referring lower than the knee, or neck pain no lower than the elbow);

• Improves on movement; and

• Is accompanied by no history of trauma.

Muscle imbalance leads to altered biomechanical stresses in joints which may precipitate cartilaginous degeneration and stiff or hypermobile joints (Marks 1993). Often, in the spine, one segment becomes damaged or degenerative as the stress it experiences is altered from that which the joint was designed to withstand. The accompanying inflammation causes fibrosis and stiffening so an adjacent joint becomes hypermobile and painful in an attempt to maintain normal functional movement. A common example of this is where stiffness of thoracic vertebral joints 1–4 causes pain at cervical 5–6, as is typical in cervical spondylosis, recognised by the forming of a ‘ledge’ between C6 and C7 and a so-called ‘dowager’s’ or ‘buffalo’ hump. Adaptation takes place in ligaments and muscles to guard the painful area, and symptoms can be produced from these soft tissues. The loading on muscles may produce spasm, fibrosis and the development of myofascial trigger spots (Travell & Simons 1992), and further postural adaptation may result.

It eventually becomes difficult to understand which changes occurred first—habitual posture, joint dysfunction or occupational stress—and a complete treatment regimen must address all aspects: correcting poor posture and poor ergonomic habits, freeing joints and their surrounding tissues, and settling soft tissue symptoms. Treatment that addresses only some facets of the problem will have only limited success. Weintraube (1986) states that treating only secondary soft tissue changes will remove compensatory mechanisms and may worsen symptoms. He suggests that, under chronic conditions, the joints should be treated first to balance the joint and soft tissue changes.

Some persistent spinal problems fall into the category of a complex chronic back pain model. As the symptoms follow a pattern of quiescence and flare-up, the patient gradually adapts her/his lifestyle. Attempts to increase activity, whether by beginning exercise programmes to increase fitness or changing work or leisure patterns, will create pain as a result of the adaptations already described. This increased irritability of symptoms may cause irritability of mood, which affects relationships with partners, family and friends. Depression or anxiety—whether transient or long term—can become a feature. The increased muscle tone experienced in either of these conditions can exacerbate musculoskeletal symptoms. An altered sleep pattern will perpetuate the problem as sleeplessness due to pain will worsen depression, while ‘tossing and turning’ due to psychological factors will worsen physical pain and stiffness. Drugs to relieve insomnia, pain or psychological symptoms may cause side effects such as constipation, which, accompanied by a reduction in physical activity, contributes to the general loss of well being. Chronic pain can become more complex in that behavioural patterns of the sufferer generally within relationships can become inextricably bound up with the whole syndrome and the disability can be a focus for dependence or caring within a relationship. This scenario can be further complicated when the patient tends to respond emotionally to pain. Further discussion of this is outside the scope of this book, but a full understanding is essential for anyone working in this field. Touch and massage can contribute to a multifactorial, holistic treatment programme for these patients but should be used as enabling techniques, to support patients in sharing in the responsibility for their own recovery, rather than to perpetuate passivity. This is particularly important for patients in whom the psychological factors outweigh the physical factors in chronic pain ‘syndrome’. These patients are best helped by a multidisciplinary team, taking a cognitive behavioural approach.

A recent and rigorously controlled study which compared massage, acupuncture and self-care education for chronic low back pain had surprising results. Patients in each of the treatment groups received therapy appropriate to their condition, thus following normal clinical practice. Treatments lasted 10 weeks, the patients being assessed at week 4 and week 10. The massage group scored significantly better than the other groups throughout the trial. A follow-up one year later showed massage and self-care scored almost equally. Acupuncture did not even achieve a significant placebo effect (Cherkin et al 2001).

Where muscle damage has occurred as a result of long-term postural stresses or trauma, inflammation will occur at the site of the lesion, which may be at a muscle–connective tissue interface, and fibrous scarring will result. If this is ignored, it will become shortened and adherent, with symptoms persisting even when the active inflammatory processes have resolved. In acute problems, muscle contraction causes pain, although a minor lesion in a strong patient may require hard muscle work to reproduce symptoms. Widthways expansion may be allowed during contraction, so contracting the muscle may not cause pain. However, stretching

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