A conceptual model for work-related neck and upper-limb musculoskeletal disorders

This paper presents a conceptual model for the pathogenesis of work-related musculoskeletal disorders. The model contains sets of cascading exposure, dose, capacity, and response variables, such that response at one level can act as dose at the next. Response to one or more doses can diminish or increase the capacity for responding to successive doses. The model is used as a framework for discussing the development of work-related muscle, tendon, and nerve disorders. It is intended as a beginning, to be modified to explain new findings as they become available. In research, it can help to identify areas needing additional data for the development and expression of work-related musculoskeletal disorders. Researchers can use it to design laboratory and field studies. In practice, it demonstrates the relationship between common exposure factors and different responses. This information can be used to evaluate and design jobs for the prevention of work-related musculoskeletal disorders.

[Diagnosis and therapy of Lyme arthritis]

Several distinct patterns of rheumatic manifestations can be seen throughout the course of Lyme borreliosis: intermittent and migratory musculoskeletal pain without objective findings, intermittent arthritis, chronic erosive arthritis, and joint deformities under affected skin in acrodermatitis chronica atrophicans. Commonly, Lyme arthritis is a late disease manifestation. A clinical history of extra-articular disease manifestations is the most reliable key to Lyme arthritis. However, arthritis often occurs without antecedent early-disease manifestations. The diagnostic significance of serological findings suggesting Lyme arthritis must be considered carefully with regard to the typical clinical features of Lyme arthritis and its potential differential diagnoses. Otherwise, Lyme arthritis will be frequently over-diagnosed. Lyme arthritis can be cured with antibiotics. However, treatment failures occur with any of the hitherto recommended regimens.

Upper extremity disorders in performing artists

Studies in the past decade have shown that a significant proportion of instrumentalists report musculoskeletal problems severely affecting their musical performance. Musicians endure daily intensive use of their upper extremities, frequently placing them in bizarre positions. Their training schedules are rigorous and long term Predisposing factors to, and treatment for, overuse syndromes, tendinitis, and tendon trauma commonly encountered by musical performers are discussed at length. Nerve entrapment has also surfaced as a major problem in musicians, and the means of evaluation and treatment and the role of surgery are put forth. Techniques for studying and analyzing the difficulties faced by instrumentalists are summarized.

Immobility in the aged

Bed rest has historically been used therapeutically in the management of many chronic maladies prevalent in elderly persons. Unfortunately, the deleterious consequences of immobility predispose elderly persons to significant functional decline and reduced quality of life. Prolonged inactivity reduces the physiologic reserve of most organ systems, particularly the musculoskeletal and cardiopulmonary systems. Consequently, muscle weakness, contracture formation, postural hypotension, and thrombogenic events are common in bed-bound patients. Fortunately, contemporary studies have dispelled the myth that inactivity fosters healing and have suggested techniques that may prevent immobility-induced dysfunction and ensure beneficial outcome in fragile and aging populations.

[Characteristics of physical therapy in diseases of the musculoskeletal system in the elderly]

Physical therapy is application of different kinds of energy for treatment. It provokes reactions by stimulation using physiological principles. Physical measures induce immediate effects as well as long-term reactions with adaptation. In diseases of the locomotor system in higher age, physical therapy is applied for diminishing pain and stiffness, amelioration of metabolism and function and especially for the maintenance of functional independence. Also fitness, good health and self-confidence can be stimulated. The age-dependent pecularities of the locomotor system, the skin and the cardiovascular system should be taken into consideration. Each method of physical treatment (hydrotherapy, heat and cold treatment, massages, exercise treatment, electrotherapy) has its age-specific peculiarities, which should be known by the treating physician. Modification of treatment can become necessary also by the kind of the disease. Dosage and technics of physical therapy must be adapted individually and supervised carefully.

Sugar and spice and everything nice: health effects of the sexual division of labor among train cleaners

Attempts have been made to justify the sexual division of labor by referring to women's relative physical weakness, lack of technical competence, and dislike for dirty work. An analysis of the work activity of train cleaners in France showed a rigid sexual division of labor, in which the task of toilet cleaning was exclusively assigned to women. Interviews and observations revealed a number of physical constraints associated with the work, and particularly with toilet cleaning. Women employees suffered from many musculoskeletal problems and were frequently absent from work. Toilet cleaning involved traveling distances of over 20 kilometers per day and maintaining uncomfortable postures. Twenty-five percent of time during the actual cleaning was spent in a crouched position. The work was complex, involving a number of choices and decisions, as well as requiring a variety of techniques adapted to the differences in the nature and location of soil. This "women's job" was dirty and physically demanding, and required technical skill. Among train cleaners, the inability to rotate jobs due to sex-typed job assignment may be associated with specific health and safety risks for both sexes.

Occupational biomechanics of the neck: a review and recommendations

Musculoskeletal disorders of the neck are becoming a major concern in industry. Several studies reported the association of neck pain, discomfort, and symptoms with different occupations in industry. Thus, the main objective of this study is to review and evaluate biomechanical techniques used in analyzing the occupational factors leading to neck pain and disorders. Recommendations for future research are also discussed.

The evolution of chronic pain among patients with musculoskeletal problems: a pilot study in primary care

Little is known about the evolution of chronic pain in primary care. Forty five patients with a four week history of musculoskeletal pain were assessed and followed up over 26 weeks by a research nurse using a structured interview and formal assessment instruments. Patients aged 18 to 65 years were recruited on presentation at two semirural Cheshire general practices and subsequently interviewed on a domiciliary visit. Twenty patients (44%) continued to have pain at 26 weeks and these patients were considered to have chronic pain. Nineteen patients had no pain after 12 weeks and a further six had no pain after 26 weeks; these patients together formed the group with acute pain. Comparing the two groups at entry into the study (pain of four weeks' duration) demonstrated significantly higher visual analogue scale scores for intensity of pain (P < 0.01) and a higher incidence of depression (P < 0.01) in the group which subsequently developed chronic pain. In this group, the presence of depression at 12 weeks was associated with higher visual analogue scale scores (P < 0.05) but at 26 weeks scores were similar in depressed and non-depressed patients. The correlation between visual analogue scale score for intensity of pain and the use of passive coping strategies to cope with pain appeared more strongly positive with duration of pain (P < 0.05 at 26 weeks). It is suggested that high pain intensity scores, the presence of depression, and the increasing use of passive coping strategies may be identifiable associations with the development of chronic pain. Areas for further research are identified.

Running injuries. A review of the epidemiological literature

Running is one of the most popular leisure sports activities. Next to its beneficial health effects, negative side effects in terms of sports injuries should also be recognised. Given the limitations of the studies it appears that for the average recreational runner, who is steadily training and who participates in a long distance run every now and then, the overall yearly incidence rate for running injuries varies between 37 and 56%. Depending on the specificity of the group of runners concerned (competitive athletes; average recreational joggers; boys and girls) and on different circumstances these rates vary. If incidence is calculated according to exposure of running time the incidence reported in the literature varies from 2.5 to 12.1 injuries per 1000 hours of running. Most running injuries are lower extremity injuries, with a predominance for the knee. About 50 to 75% of all running injuries appear to be overuse injuries due to the constant repetition of the same movement. Recurrence of running injuries is reported in 20 to 70% of the cases. From the epidemiological studies it can be concluded that running injuries lead to a reduction of training or training cessation in about 30 to 90% of all injuries, about 20 to 70% of all injuries lead to medical consultation or medical treatment and 0 to 5% result in absence from work. Aetiological factors associated with running injuries include previous injury, lack of running experience, running to compete and excessive weekly running distance. The association between running injuries and factors such as warm-up and stretching exercises, body height, malalignment, muscular imbalance, restricted range of motion, running frequency, level of performance, stability of running pattern, shoes and inshoe orthoses and running on 1 side of the road remains unclear or is backed by contradicting or scarce research findings. Significantly not associated with running injuries seem age, gender, body mass index, running hills, running on hard surfaces, participation in other sports, time of the year and time of the day. The prevention of sports injuries should focus on changes of behaviour by health education. Health education on running injuries should primarily focus on the importance of complete rehabilitation and the early recognition of symptoms of overuse, and on the provision of training guidelines.

Musculoskeletal signs of metabolic and systemic diseases in childhood

Many metabolic and systemic disorders affect the musculoskeletal system in growing children. This review surveys some of the recent literature in several diverse areas, including new radiologic methods to determine bone mineralization and their use in children with juvenile arthritis and other systemic diseases, bone disorders in childhood, and the association of endocrinopathies and musculoskeletal symptoms.

Musculoskeletal pain and work disability

Musculo-skeletal pain caused by neck and back injury, cumulative trauma to the upper extremities, fibromyalgia, and reflex dystrophy is an important cause of worker disability. Physicians are involved not only in the care of injured workers, but in providing independent medical opinions regarding such injuries. Advances in medical knowledge permit better understanding and management of these injuries, and it is the responsibility of all physicians to provide accurate diagnosis, treatment, and information to patients, employers, insurers, and the workers compensation system.

Rheumatic fever and disorders of the musculoskeletal system

New information provided on the pathogenesis and management of rheumatic fever is of current interest. Invasive disease by group A streptococci has been shown to be due to production of toxin A. The natural history and immunopathologic basis for chronic Lyme arthritis are reported. Attention is drawn to pyomyositis and clinical presentation of chronic fatigue syndrome in children. Patients with Sweet's syndrome often have antineutrophil cytoplasmic autoantibodies. Biopsy specimens of panniculitis should be taken to aid treatment. Long-term outcome in chronic osteomyelitis is favorable; recommendations on the rational use of imaging have been reported.

[Etiology and diagnosis of chronic shoulder pain]

Shoulder pain of more than three months' duration is regarded as chronic. Activity with an elevated arm is a risk factor, due to reduced local flow of blood to the supraspinatus muscle. Knowledge about normal shoulder biomechanics and dysfunctional behaviour patterns is essential when treating patients with chronic pain. It is necessary to consider psychosocial factors in addition to local pathology. The clinical examination should enable the physician to distinguish between referred and true shoulder pain and between restricted and free passive range of movement. Diagnoses may be classified into eight groups. The association between pain and degenerative changes has yet to be solved. This emphasizes the danger of deciding treatment without matching findings from radiological examinations with clinical signs and symptoms.

Unusual occupational rheumatologic and musculoskeletal disorders

Musculoskeletal disorders are among the most common clinical occupational problems, but occupational rheumatologic diseases are among the rarest. The identification of one or more cases of unusual diseases or epidemiologically unusual presentations must alert the clinician to the possibility of group exposure and risk and emphasizes the need to explore these using the model of "sentinel health event." Cumulative trauma disorders, including thoracic outlet syndrome and reflex sympathetic dystrophy syndrome, and occupational rheumatologic disorders of other etiology (Raynaud's phenomenon, scleroderma, fluorosis, osteomalacia, aseptic necrosis, and Caplan's syndrome) are reviewed.

Design of check-out systems including laser scanners for sitting work posture

Forty-six laser scanner operators were compared with 106 cashiers operating conventional cash registers. The influence of job rotation on the two groups was evaluated, and several design features were examined. For this purpose the prevalence of musculoskeletal disorders was determined by means of a questionnaire and a physical examination. In addition, a three-dimensional movement analysis system was employed. Work postures were analyzed with the Ovako working analysis system. The results indicate that a beneficial effect on the musculoskeletal system is achieved by combining the operation of a laser scanner with job rotation. The study also points out the need for better equipment, including flat scanners and smaller keyboards, and a change in the angle between the scanner and the take-off belt running up to the cashier.

Joint hypermobility in adults referred to rheumatology clinics

Joint hypermobility is a rarely recognised aetiology for focal or diffuse musculoskeletal symptoms. To assess the occurrence and importance of joint hypermobility in adult patients referred to a rheumatologist, we prospectively evaluated 130 consecutive new patients for joint hypermobility. Twenty women (15%) had joint hypermobility at three or more locations (greater than or equal to 5 points on a 9 point scale). Most patients with joint hypermobility had common musculoskeletal problems as the reason for referral. Two patients referred with a diagnosis of rheumatoid arthritis were correctly reassigned a diagnosis of hypermobility syndrome. Three patients with systemic lupus erythematosus had diffuse joint hypermobility. There was a statistically significant association between diffuse joint hypermobility and osteoarthritis. Most patients (65%) had first degree family members with a history of joint hypermobility. These results show that joint hypermobility is common, familial, found in association with common rheumatic disorders, and statistically associated with osteoarthritis. The findings support the hypothesis that joint hypermobility predisposes to musculoskeletal disorders, especially osteoarthritis.

Posttraumatic calcification of the annular ligament of the radius

Eight cases of calcification following anterior dislocation of the head of the radius are described. It was demonstrated as early as 2 weeks after injury and in 7 cases appeared in the form of a shell on the volar aspect of the head. The other type exhibits a cuff of calcification related to the radial neck. Parallel cases are drawn from a literature review, and the distinction is made between calcification in the disrupted annular ligament/capsule or oblique cord and myositis ossificans. Regression in several cases may be a consequence of open reduction.

Persistent antinuclear antibodies in children without identifiable inflammatory rheumatic or autoimmune disease

One hundred eight children with musculoskeletal pain considered not to be due to an autoimmune or inflammatory disease had an antinuclear antibody (ANA) test performed. Twenty-four of these children were ANA positive on HEp-2 cell substrate at a screening serum dilution of 1:20. A positive ANA test persisted in 21 of 24 of the patients over a mean time period of 38 months (range 1 to 103 months). No sera from any patient at initial evaluation had anti-DNA antibodies by radioimmunoassay or by indirect immunofluorescence on Crithidia luciliae. One patient recently developed elevated anti-DNA (radioimmunoassay) antibodies but still has a negative assay on C luciliae. Four patients had antibodies to core histones by immunoblotting. None had antibodies to Sm, RNP, Ro (SS-A), or La (SS-B) by counterimmunoelectrophoresis. No patient developed an overt inflammatory or autoimmune disease during a mean follow-up period of 61 months (range 13 to 138 months). A child with musculoskeletal pain and a positive test for ANA, but with no clinical evidence at presentation of inflammatory or autoimmune disease, is at low risk of imminently developing such a disease.

Musculoskeletal complications after renal transplantation: pathogenesis and treatment

Renal transplantation is associated with several abnormalities of function and structure of the musculoskeletal system. Some of these skeletal problems result from incomplete resolution of abnormalities of bone and mineral metabolism present at the time of transplantation. In this regard, persistent hyperparathyroidism, diabetes mellitus type 1, and accumulation of beta 2-microglobulin may lead to residual skeletal effects despite excellent function of the allograft. Persistent hyperparathyroidism may accelerate bone loss and increase the risk for osteonecrosis, as well as cause hypercalcemia and hypophosphatemia; some patients with severe hyperparathyroidism require parathyroid surgery. Osteonecrosis is the most debilitating skeletal complication after transplantation and frequently requires surgical therapy. Although osteomalacia associated with aluminum overload generally resolves after transplantation, bone complications due to dialysis amyloidosis and diabetes mellitus type 1 often fail to improve. Alternatively, skeletal abnormalities can be acquired after transplantation. Most of the new derangements of bone and mineral metabolism are due to the immunosuppressive medications. Toxic effects of glucocorticoids on bone contribute to the pathogenesis of osteonecrosis, increase the risk for fractures by decreasing cancellous bone mass and synthesis of bone matrix, and dampen the linear growth response in pediatric recipients. Whether cyclosporine independently causes appreciable toxic effects on bone metabolism is not yet clear, but use of this drug increases the prevalence of gout and dental problems. Osteonecrosis, osteopenia, and short stature remain important skeletal complications in recipients of renal allografts. Therapeutic efforts should be directed toward alleviating pretransplant bone disease and attenuating bone loss after transplantation.

[Only limited effect of treatment of thyroid gland diseases on symptoms of musculoskeletal system]

In order to assess the long term effect of treatment for thyroid dysfunction on musculoskeletal symptoms, 102 patients were traced by a computer search; these patients visited two outpatient clinics of rheumatology and were known to have thyroid disorders. Of these 102 patients, 58 patients met the study criteria of having abnormal thyroid function tests at first visit to the outpatient clinic; 46 patients participated in the study. They were interviewed with a structured questionnaire about their past and current musculoskeletal complaints. The 46 patients (45 females, 1 male) had a mean age at interview of 58 years (range 21-81); 37 and 9 patients had been treated for hypothyroidism and hyperthyroidism respectively. The thyroid dysfunction was considered the only explanation of the original musculoskeletal symptoms in 24 patients (group I), in 19 patients an additional (rheumatological) diagnosis was made (group II), and in 3 patients no apparent relation between musculoskeletal complaints and thyroid dysfunction was found. After treatment for thyroid dysfunction the original complaints decreased in 52% and 47% of the patients in group I and II, respectively. At the time of the follow-up study (mean follow-up duration 67 months) 91% of the patients had musculoskeletal symptoms, 80% of the patients said their present complaints were similar to their original symptoms. Treatment for thyroid dysfunction resulted in a temporary beneficial effect on musculoskeletal symptoms in 50% of the patients; in 91% symptoms persisted.

Cat-scratch disease: orthopaedic presentation

Although cat-scratch disease is not uncommonly treated by pediatricians, it is rarely seen by orthopaedists. In this review of cat-scratch disease, two cases with orthopaedic manifestations are high-lighted. One patient had a positive bone scan in the distal humerus that simulated osteomyelitis on presentation. The second patient presented with a rapidly enlarging soft-tissue mass in the arm that resembled a soft-tissue sarcoma. The diagnosis of cat-scratch disease eventually was made late in the course of management in both cases. Both patients underwent surgical drainage and evacuation of the suppurated lymph node and recovered without sequelae.

Back disorders and health problems among subway train operators exposed to whole-body vibration

Back disease associated with whole-body vibration has not been evaluated for subway train operators. A recent study demonstrated that this group is exposed to whole-body vibration at levels above the international standard. To investigate this risk further, a self-administered questionnaire survey was conducted among subway train operators (N = 492) and a similar reference group (N = 92). The operators had a higher prevalence than the referents in all aspects of back problems, particularly for cervical and lower back pain. In a multiple logistic regression model, the odds ratio for sciatic pain among subway train operators was 3.9 (95% CI 1.7-8.6); the operators also had a higher risk of hearing-related problems (odds ratio 3.2, 95% CI 0.6-17.4) and of gastrointestinal problems (odds ratio 1.6, 95% CI 1.1-2.5). Although a cumulative dose-response relationship could not be statistically demonstrated, the findings appear to be related to exposure to whole-body vibration and inadequate ergonomic conditions.

Musculoskeletal discomfort and feeling of fatigue among female professional workers: the need for ergonomics consideration

Subjective feeling of general fatigue and physiological strain were studied in one hundred female professional employees of industrial worker and full-time nurses. Using an interview questionnaire the feeling of fatigue were studied. The subjects were asked to indicate on the body diagram all the areas of musculoskeletal pain from which they perceived discomfort. Furthermore physical strength test consisting of grip test, back and leg strength test were carried out before and after work on all subjects. The results indicated that the two groups of employees showed different symptoms of "pain" and/or "fatigue," with regard to the different parts of body. It was also noted that the physical strength after work was lower for both groups as compared to before work and even lower for the industrial workers than the nurses. The feeling of fatigue between the two investigated groups was not significantly different, but for the musculoskeletal pain was highly significantly different. The worker group used also more pain-killing drugs for releasing the muscle pain. It was evident that ergonomics intervention for female professional workers was of great importance and urgency, particularly for making the workplace more human. Improvement of the working conditions, better organization of work, and ergonomics interventions are suggested as necessary measures for reduction of pain and feeling of discomfort.

Chronic morbidity of former prisoners of war and other Australian veterans

OBJECTIVE

This report is the first summary article from a review of studies on long-term morbidity associated with war service or internment, commissioned by the Sir Edward Dunlop Medical Research Foundation.

DATA SOURCES

The Medlars database, from 1966 to the present, under the terms military personnel, veterans, veterans' disability claims, combat disorders and prisoners (matched against war); databases of the Department of Veterans' Affairs (Victoria) and the Central Library, Commonwealth Department of Defence, using the term "prisoner of war"; and the microfiche listings of the Department of Veterans' Affairs, under "prisoner of war" and "repatriation". Only studies in English or French were reviewed, reaching a total of 172.

STUDY SELECTION

Forty-eight studies are considered in the present summary, presenting the most significant evidence about long-term morbidity attributable to war-time experiences. Studies concerning Australian veterans are emphasised.

DATA EXTRACTION

Studies considered valid were summarised for an annotated bibliography, but only reports of major public health significance are reviewed here.

DATA SYNTHESIS

The review confirms that strongyloidiasis, peptic ulcer, anxiety states, depression and hepatitis B are more prevalent in former prisoners of war than in relevant comparison groups. We have not identified further diagnoses that should be attributed specifically to war-time exposures. Attribution of long-term neurological and musculoskeletal disorders to war-time exposures remains uncertain.

CONCLUSIONS

Former prisoners of war and veterans constitute a population of survivors highly selected by the rigours of war and imprisonment. Occurrence of the five conditions listed above may be reasonably attributed to war-time exposure. We recommend further research on ageing (including neurological, visual, hearing and musculoskeletal disability), family disruption and rehabilitation strategies in these groups.

Musculoskeletal disorders. When are they caused by hormone imbalance?

Often, the source of a musculoskeletal problem can be traced to an endocrine disorder. For example, carpal tunnel syndrome is not uncommon in patients who are pregnant or have diabetes, hypothyroidism, or acromegaly. Joint problems and arthritis are other common findings in diabetes, pregnancy, and hyperparathyroidism. Muscle weakness or stiffness is seen in both hypothyroidism and hyperthyroidism, and muscle wasting is a characteristic of adrenocorticoid insufficiency. Bone disorders are common with glucocorticoid excess, acromegaly, and hyperparathyroidism. Some presentations are a classic picture of a specific endocrine condition and are readily recognized if the index of suspicion is appropriately high.

Is the benign joint hypermobility syndrome benign?

Over a period of two years, joint hypermobility was identified in 95 female and 19 male patients who attended rheumatology and rehabilitation units in Ismailia city. Pauciarticular pains referring to large and medium-sized joints was their most frequent complaint. Clinical diagnosis of carpal and/or tarsal tunnel syndromes was made in 45.6% of patients, and various forms of soft tissue rheumatism were evident in 73% of them. On radiologic evaluation of the involved joints, 60.5% of the examined patients showed significant degenerative lesions. The most prominent finding in the study, however, was the aggregation of varieties of articular and extra-articular abnormalities in the same patient. Extra-articular features included high frequencies of occurrence of varicose veins, piles and uterine prolapse among other abnormalities. Thus, results of the study lend support to the view that joint hypermobility predisposes to several articular and nonarticular lesions raise serious questions about the reputable benignity of the syndrome.

Musculoskeletal disorders in the haemophilias

The management of the haemophilias has been improved by the advent of potent consistent clotting factor replacement therapy. The previously lethal major complications such as intracerebral haemorrhage are now rare, and the infective complications of treatment, most notably hepatitis and AIDS, are now potentially preventable with the new synthetic products. There is also the prospect of 'cure' by gene insertion therapy. Advanced arthropathy has been minimized but not prevented by early effective treatment of haemarthroses, and there is a diminishing legacy of severely affected patients many of whom may require joint replacement surgery. The present group of such patients has a high prevalence of HIV-1 infection and an increased risk of joint sepsis. The available avenues of treatment for the subacute stage of the arthropathy have not been particularly effective, emphasizing the need to prevent recurrent bleeding. The development of a multidisciplinary team-management approach in centres of expertise has been a significant factor in the improved longevity, life satisfaction and preserved mobility now available to most haemophiliacs.

Postrace morbidity among runners

We examined two general measures of morbidity, musculoskeletal problems and respiratory symptoms, among participants of a 42 km race. We compared the morbidity experience of these participants to runners racing shorter distance events (5 km and 10 km) on the same day. Male marathon runners were almost twice as likely (and female marathon runners four times as likely) to report a lower extremity musculoskeletal problem in the month after the race as nonmarathon runners. Although adjusting for other factors did not change the crude odds ratio for either men or women, logistic regression results indicated that the strongest factor associated with lower extremity musculoskeletal problems in the month after the marathon was the report of a musculoskeletal problem in the year before the marathon. Neither male nor female marathon runners reported an excess of respiratory symptoms compared to those who ran shorter distances. However, a report of respiratory symptoms in the month before the race was statistically associated with respiratory symptoms in the month after the race. These results suggest that runners who have had lower extremity musculoskeletal problems in the year before, or those who have recently experienced respiratory symptoms, should use caution when preparing for and recovering from racing events.

Pathophysiological mechanisms involved in genesis and spread of muscular tension in occupational muscle pain and in chronic musculoskeletal pain syndromes: a hypothesis

This paper introduces a pathophysiological model for the cause of muscular tension and pain in occupational pain syndromes and chronic muskuloskeletal pain syndromes, which also might clarify why these conditions have a tendency to perpetuate themselves and spread from one muscle to another. The model can briefly be described as follows. Metabolites produced by (static) muscle contractions stimulate group III and IV muscle afferents, which activate gamma-motoneurones projecting to both homonymous and heteronymous muscles. The gamma-motoneurones influence the stretch sensitivity and discharges of secondary and primary spindle afferents. Increased activity in the primary muscle spindle afferents enhances the muscle stiffness, which leads to further production of metabolites in both homo- and heteronymous muscles. Increased activity in secondary spindle afferents, which project back to the gamma system, constitutes a 'built in' second positive feedback loop which may perpetuate the condition with less 'support' from activity in group III and IV muscle afferents.

Late effects of childhood malignancies seen in Western Australia

Eighty-nine pediatric oncology patients, in remission and off treatment for at least 4 years, were reviewed annually in the Late Effects Clinic of Princess Margaret Hospital for Children in Perth, Western Australia. Interval from time of diagnosis to follow-up ranged from 4 to 23 years (mean 10.8 years). Acute lymphoblastic leukemia (ALL) (40%) and Wilms' tumor (27%) were the most common primary malignancies in this group. Late sequelae included musculoskeletal abnormalities (23 children), growth hormone deficiency (11), second tumors (9), learning difficulties (7), puberty and fertility problems (4), and hypothyroidism (4). These complications were most often related to radiation therapy. The need for prolonged, regular follow-up of survivors of childhood malignancy for early detection of late sequelae and subsequent intervention is stressed.