Tendon lesions and soft tissue rheumatism--great outback or great opportunity?

Gene expression and matrix turnover in overused and damaged tendons

Chronic, painful conditions affecting tendons, frequently known as tendinopathy, are very common types of sporting injury. The tendon extracellular matrix is substantially altered in tendinopathy, and these changes are thought to precede and underlie the clinical condition. The tendon cell response to repeated minor injuries or "overuse" is thought to be a major factor in the development of tendinopathy. Changes in matrix turnover may also be effected by the cellular response to physical load, altering the balance of matrix turnover and changing the structure and composition of the tendon. Matrix turnover is relatively high in tendons exposed to high mechanical demands, such as the supraspinatus and Achilles, and this is thought to represent either a repair or tissue maintenance function. Metalloproteinases are a large family of enzymes capable of degrading all of the tendon matrix components, and these are thought to play a major role in the degradation of matrix during development, adaptation and repair. It is proposed that some metalloproteinase enzymes are required for the health of the tendon, and others may be damaging, leading to degeneration of the tissue. Further research is required to investigate how these enzyme activities are regulated in tendon and altered in tendinopathy. A profile of all the metalloproteinases expressed and active in healthy and degenerate tendon is required and may lead to the development of new drug therapies for these common and debilitating sports injuries.

Regional musculoskeletal conditions: shoulder pain

About half the population has at least one episode of shoulder pain yearly. History and clinical examination are cornerstones in the evaluation of the patient. Shoulder pain at the work place is associated with job strain: lack of control and work with elevated arms and hand tools. Clinical skills and knowledge about red and yellow flags and biomechanics are essential to perform a systematic and reliable evaluation. The diagnostic validity of clinical tests for rotator cuff tear, impingement syndrome and superior labral tears is equal or better than ultrasound and magnetic resonance imaging. Non-steroidal anti-inflammatory drugs and cortico-steroidal injections have documented short-term pain relief. Additionally, the physician should attempt to give the patient simple advice and reinforce active coping strategies. One randomized study suggests that a proper physiotherapy regimen and surgery are equally effective for the impingement syndrome. Further research should address the cost-effectiveness of diagnostic methods and treatments.

Association of HLA-DRB1 alleles with giant cell tumour of bone

AIM

To examine the possible influence of the MHC class II antigens alleles in the formation of the multinucleate aggressive giant cell tumour of bone.

METHODS

HLA class II antigen alleles were investigated in eight white patients from north east England with confirmed diagnosis of giant cell tumour of bone. All had locally aggressive, immunophenotypically HLA-DR negative giant cell tumours.

RESULTS

Five of the eight patients were found to be positive for HLA-DRB1*0801/3, the distribution of this allele in healthy white controls being quite low (2%). All but one of the patients possessing DRB1*080 also expressed DRB1*070.

CONCLUSIONS

HLA-DRB1*080 is pre-dominant in patients with immunophenotypic HLA-DR negative giant cell tumour of bone; individuals with the genotype 070/080 are at particularly high risk of developing giant cell tumour of bone.

Etiology and pathophysiology of chronic tendon disorders in sports

In sports medicine, a chronic overuse injury is defined as a long-standing or recurring orthopedic problem and pain in the musculoskeletal system, which started during exertion due to repetitive tissue microtrauma (1). Repetitive microtrauma, which is basically repeated exposure of the musculoskeletal tissue to low-magnitude forces, results in injury at the microscopic level, and no single acute trauma is normally involved in the pathogenesis of an overuse injury. In chronic tendon disorders, 'overuse' implies that the tendon has been strained repeatedly to 4-8% strain until unable to endure further tension, whereupon injury occurs (2). The structure of the tendon is disrupted micro- or macroscopically by this repetitive strain, i.e. collagen fibrers begin to slide past one another, causing break-age of their cross-linked structure, and denaturate; inflammation, edema and pain result. Thus, tendinitis, peritendinitis, tenosynovitis, insertion tendinitis, tendinous bursitis or apophysitis is the earliest clinically recognizable manifestation of overuse tendon injury (3).

Tenascin-C and human tendon degeneration

We investigated the distribution of tenascin in supraspinatus tendons to determine whether an alteration in tenascin expression was associated with human tendon degeneration. Tenascin was present in all of the tendons studied, although with two distinct patterns of expression. First, tenascin was associated with organized, fibrous regions of the tendon matrix that were typical of the normal tendon structure. This distribution is consistent with a role for tenascin in collagen fibril organization, perhaps maintaining the interface between fibrils and adjacent structures. Second, although tenascin was generally absent from poorly organized matrix in degenerate tendons, it was strongly associated with some rounded cells in disorganized fibrocartilaginous regions that were more abundant in pathological specimens. Tenascin was also found around infiltrating blood vessels, with more intense staining associated with a mononuclear cell infiltrate. Western blotting of tendon extracts showed differences in tenascin isoform expression, with only the small (200-kd) tenascin isoform found in normal tendons. Degenerate tendons also expressed the 300-kd isoform, consistent with a role for the larger tenascin isoform in tendon disease, potentially stimulating tenocyte proliferation, cell rounding, and fibrocartilaginous change. Proteolytic fragments of tenascin were detected but only in ruptured tendons, an indication of matrix remodeling in degenerate tendons, with fragment sizes consistent with the activity of matrix metalloproteinase enzymes.