The effect of forearm posture on wrist flexion in computer workers with chronic upper extremity musculoskeletal disorders

<p>Abstract</p> <p>Background</p> <p>Occupational computer use has been associated with upper extremity musculoskeletal disorders (UEMSDs), but the etiology and pathophysiology of some of these disorders are poorly understood. Various theories attribute the symptoms to biomechanical and/or psychosocial stressors. The results of several clinical studies suggest that elevated antagonist muscle tension may be a biomechanical stress factor. Affected computer users often exhibit limited wrist range of motion, particularly wrist flexion, which has been attributed to increased extensor muscle tension, rather than to pain symptoms. Recreational or domestic activities requiring extremes of wrist flexion may produce injurious stress on the wrist joint and muscles, the symptoms of which are then exacerbated by computer use. As these activities may involve a variety of forearm postures, we examined whether changes in forearm posture have an effect on pain reports during wrist flexion, or whether pain would have a limiting effect on flexion angle.</p> <p>Methods</p> <p>We measured maximum active wrist flexion using a goniometer with the forearm supported in the prone, neutral, and supine postures. Data was obtained from 5 subjects with UEMSDs attributed to computer use and from 13 control subjects.</p> <p>Results</p> <p>The UEMSD group exhibited significantly restricted wrist flexion compared to the control group in both wrists at all forearm postures with the exception of the non-dominant wrist with the forearm prone. In both groups, maximum active wrist flexion decreased at the supine forearm posture compared to the prone posture. No UEMSD subjects reported an increase in pain symptoms during testing.</p> <p>Conclusion</p> <p>The UEMSD group exhibited reduced wrist flexion compared to controls that did not appear to be pain related. A supine forearm posture reduced wrist flexion in both groups, but the reduction was approximately 100% greater in the UEMSD group. The effect of a supine forearm posture on wrist flexion is consistent with known biomechanical changes in the distal extensor carpi ulnaris tendon that occur with forearm supination. We infer from these results that wrist extensor muscle passive tension may be elevated in UEMSD subjects compared to controls, particularly in the extensor carpi ulnaris muscle. Measuring wrist flexion at the supine forearm posture may highlight flexion restrictions that are not otherwise apparent.</p

BMP treatment for improving tendon repair. Studies on rat and rabbit Achilles tendons

We wanted to improve tendon healing by adding a growth factor. Bone Morphogenetic Proteins (BMPs) are well known to stimulate bone healing and bone formation. The local environment is of major importance for cell differentiation after a BMP has been added. Cartilage Derived Morphogenetic Proteins (CDMPs) -1, -2 and -3 (BMP 14, 13 and 12 or GDF 5, 6 and 7) form a subgroup in the BMP-family and are closely related to OP-1 (BMP 7). CDMP implants have been shown to induce bone and cartilage as well as tendon and ligament-like tissue. Our hypothesis has therefore been that if a BMP were added in a tendon environment, a tendon-like tissue would be induced. We have developed models in rats and rabbits where the Achilles tendon is transsected. To influence tendon healing, different BMPs (OP-1, CDMP-1. -2 and -3) were added, either on a collagen carrier, or as a local injection into the tendon defect. The tendons were evaluated by histology and mechanical testing at different time-points after transection. The results show that also when the mechanical environment would favour the formation of a tendon-like tissue, OP-1 reduced tendon strength in aid of bone formation. In contrast, CDMP-1, -2 and -3 had a beneficial effect upon tendon healing in rats. More callus tissue was produced than in controls, and strength and stiffness were improved, although minor amounts of bone and cartilage were detected in the tendon callus. Cartilage and bone formation sometimes occur normally during Achilles tendon healing in rats. In the rabbit model, where the healing situation is more similar to the clinical situation, the positive result with CDMP-2 was repeated. Moreover, in rabbits no bone or cartilage was found. The results suggest that conservative treatment of Achilles tendon ruptures with injection of a CDMP in combination with early rehabilitation might afford a good alternative to surgical treatment