Particular principles of vocational rehabilitation of musculo-skeletal disorders
The literature on medical rehabilitation of patients with musculo-skeletal disorders is extensive [1, 2, 3], but the literature about vocational rehabilitation of those patients is considerably less [4, 5, 6]. What then, are the characteristics of vocational rehabilitation?
One particular feature is that a job is involved in the process. The present chapter is focu- sed on job-related factors of rehabilitation and will not describe general principles of medical rehabilitation of patients with diseases, disorders or injuries of the locomotor system.
If musculo-skeletal disorders, in this context, are divided into two main categories, one part can be musculo-skeletal painful conditions where the specific origin of the pathogenesis is not proven to be loading events of the work place, but for the patient still involve easily elicited pain in situations of load during working, e.g. arthrosis of cervical spinal joints, coxarthrosis, gonarthrosis.
The second part of the musculo-skeletal disorders can be the work related musculo- skeletal disorders (WMSDs) where loading situations of the patients’ work tasks are asso- ciated with the etiology of the painful disorder [7], e.g. rotator cuff tendonitis, trapezius pars descendens myalgia, levator scapulae tendalgia, cervical spine extensor myalgia/ten- donitis (or “tension neck syndrome”), lateral epicondylitis, hand-wrist tendonitis.
For both above mentioned categories the vocational rehabilitation measures must include improvement of the patient’s work situations. In the second category with WMSDs it is crucial to eliminate the pathogenetic factors that have caused the patient’s disease or disorder. Without changes in the working conditions the patient will get a recurrence after resuming work with the same tasks unchanged. This means that a tho- rough investigation of the patient’s work history and work tasks must be performed, as well as inspection of the work place. In many countries the employer has an extensive res- ponsibility to participate in vocational rehabilitation of this kind of patients. The pre-
in musculo-skeletal disorders
– with examples mainly from the neck and shoulder region
J. Ekholm and K. Schüldt Ekholm
ventive aspect is important [8]. If the patient is merely put on another task and his/her previous work station is unchanged some other employee will be at risk of getting the same WMSD.
For patients in the first mentioned category with disease or disorders not directly gene- rated by the work load, the situation is somewhat different. In principle even modest loa- ding can generate troublesome pain because the disease may generate easily elicited pain even if the load is light [9]. For these patients, too, the analysis of the work task is of great importance, since it might be possible to improve the situation by means of ergonomic measures. In addition, it may be important to inform the patient that the underlying disease is not produced by the work load itself. However, even for these patients the risk of recurrence exists, without changes in the working conditions.
Rough categorization of muscular
and tendinous pain affected by external load
A rough grouping of common muscular pain conditions with tendon disorders included, related to vocational rehabilitation needs is (i) regional pain which has a load-related pathogenesis including work-related musculo-skeletal disorders (WMSDs) containing neck and/or shoulder pain, with or without pain of upper limb, and tendon disorders of hand and forearm, certain forms of hip and knee arthrosis; (ii) regional pain with no proven load rela- ted pathogenesis as, for example, arthritis and spondylosis, myofascial pain syndromes and (iii) widespead pain conditions e.g., fibromyalgia syndrome.
Occurrence of musculo-skeletal disorders in the context of vocational rehabilitation
The prevalence pattern of acute or subacute diseases or injuries and short-time sick leave is different from persistent (chronic) conditions common in long-term illness absence. The selection of patients influences the prevalence pattern. Often patients who have been assessed as having vocational rehabilitation needs have been sick-listed for a long time.
In many of those on long-term sick leave, musculo-skeletal disorders are the domi- nating factor.
About half of those on long-term sick-leave, awaiting decisions about a disability pension or vocational rehabilitation, will have musculo-skeletal diagnoses, of which low back pain and neck-shoulder pain represent a substantial portion [10, 11].
Vocational rehabilitation of patients with neck and shoulder pain conditions,
with or without arm pain
Medical investigation
A medical examination must be undertaken to establish the diagnosis and pathophysio- logy underlying the symptoms. In principle, three different categories of load-related conditions can be identified. If the neck extensors are overused due to uninterrupted contraction of the dorsal neck muscles in situations where the head and neck are kept in a markedly bent position persistent pain may be generated in the dorsal neck muscles, their origins or insertions. This result in dorsal neck myalgia/tendonitis.
Overuse of shoulder girdle elevators may give persistent pain in one or more of the shoulder girdle elevating muscles – trapezius pars descendens, levator scapulae or the rhomboids with tendons.
Overuse of muscles and tendons involved in coordination of movements between the scapula and humeral bone may result in persistent painful conditions, such as rotator cuff tendonitis, biceps brachii proximal tendonitis.
It is important to analysis the type of pain involved; nocioceptive, neurogenic, psy- chogenic, or pain of unknown origin [12, 13]. Some patients have more than one type of pain, e.g. nocioceptive pain in cervical spine structures in combination with neurogenic pain in the form of radiculopathy. Different types of pain require different treatment strategies. A common combination of pain types is focal nocioceptive musculo-skeletal pain with referred pain in shoulders or upper extremity. In a selected group of women who were working in spite of pain, referred pain was present in about one third with focal pain in neck and/or shoulder [14]. Referred pain in combination with neck and/or shoulder pain as source of brachialgia is more common than neurogenic pain. An impor- tant step in the medical investigation is to map functional impairments, activity limita- tions and participation restrictions according to the ICF structure [15]. In vocational rehabilitation the analysis of environmental physical, social, and attitudinal factors is par- ticularly important.
Vocational rehabilitation measures
Vocational rehabilitation measures must include efforts to improve the patient’s working conditions. This requires ergonomic analyses which determine the actions taken.
Individual ergonomic measures for patients with a cervical spine extensor myalgia or ten- donitis should aim at producing working positions with less forward bend of the head and neck. For sitting postures, changes might consist of raising the computer screen, tilting the table surface for an work object, and similar changes aiming at a more vertical posture of the neck and head [16]. In addition to the loading moment of the head and neck, the level of muscle activity in the cervical spine extensors is influenced by the sitting angle of the
trunk. If the trunk is slightly inclined backwards and supported by a backrest, the level of acti- vity of the cervical spine extensors and the trapezius pars descendens is decreased [17, 18].
The shoulder girdle elevators are continuously active when the upper limbs are in abducted or forward flexed positions, common in a great number of working situations.
It is therefore unsurprising that shoulder girdle myalgia/tendinitis is prevalent [7].
Ergonomic measures for this kind of patients aim at reducing the load on the elevators of the shoulder girdle. This can be achieved in different ways, e.g. arm support, arm sus- pension [7, 19], wrist support, the work object positioned closer to the trunk [16], and also suspension of the work tool. Some patients tend to elevate the shoulder girdle unconsciously even in less strenuous situations e.g. during work with computer stations.
These patients may benefit from exercises related to writing on computer and can be trai- ned in relaxation with EMG-biofeedback technique [20].
It has been shown that the duration of a muscle contraction is a major factor in crea- ting muscular discomfort and pain [16], irrespective of whether the contraction is static or dynamic. This means that work tasks that imply contractions with few interruptions with low activity levels tend to be more risky than those in which there are frequent inter- ruptions [16]. This can be utilized in vocational rehabilitation. Patients with myalgia can alter their work technique aiming to perform the task with more frequent short pauses in muscle contractions (“micro pauses”).
Rotator cuff tendonitis (sometimes combined with subacromial bursitis), is related to the muscular moment of force needed to move the arm or keep the arm in a particu- lar position in relation to the scapula. The rotator cuff muscles are active in almost all movements of the shoulder joints [21] to generate forces keeping the caput in the glenoid cavity. Individual ergonomic measures for patients with rotator cuff tendonitis should aim at reducing the load on the arm either by means of improved positioning with shor- ter lever arms or by means of suspension or support of the arm plus burden/tool. The maximum muscular torque in abduction is for women about 40% of that for men [22]
which – for a given level of load – leads to a proportionally higher utilization of muscu- lar capacity in women than in men (e.g. when women use work stations designed for men). Epidemiological studies [7] have shown that work with the upper extremities above the level of shoulder joints is a risk factor for “shoulder tendonitis”, e.g. ship yard welders, women car fitters and other. Patients with rotator cuff tendonitis should there- fore select work tasks where they don’t need to work with hands above shoulder level.
Extreme-joint-position pain and its measures
Another variant of nocioception is the pain perceived when joints are kept in a sustained extreme joint position, i.e. at the limit of the range of motion [9, 23, 24]. This condition may occur, for example, when the cervical spine is kept rotated, forward flexed, and backward extended due to the content of work tasks. Examples of situations at the work place where there is a risk of extreme-joint-position pain are side-positioned drivers of trucks in a stock-in-trade, reversing a car or other vehicles, standing work at a low table, painting a ceiling and the like. The risk of extreme-joint-position pain is increased if the
range of motion in the cervical spine is reduced and/or the patients have easily elicited pain due to e.g. spondylosis, arthritis, or the sequelae of traumatic cervical spine distor- tion. Vocational rehabilitation in these cases must entail an investigation of the patient’s work with the aim of mapping the possible events where the extreme-joint-position may occur, for instance by means of video film. The next step is to make the patient aware of the situations where this occurs, e.g. by watching a video with the patient. With the goal of changing their work technique patients may begin to train in a program of body awa- reness to perform their tasks without extreme-joint-positions. The final step may be to train the patient in new work techniques.
Conditions with widespread pain, e.g. the fibromyalgia syndrome
The aetiology of the fibromyalgia syndrome (FMS) is unknown. However, some of the pathophysiology has been described. One theory is based on the concept of general impaired pain modulation [25]. The aetiology of the syndrome is not associated with physical work load, but pain intensity is usually increased by external load and FMS patients do not have the normal increase of pressure pain threshold during muscle contractions [26]. FMS patients often report increased pain intensity during muscular efforts either in the form of work or exercise [12]. The content of vocational rehabilita- tion of FMS should include body awareness training to avoid unnecessarily eliciting or increasing pain due to external load [27]. The likelihood of successful vocational rehabi- litation increases if the patient can resume employment with low physical load and little stress.
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