Biocompatability of hydroxyapatite composite as a local drug delivery system.

PURPOSE: To investigate the biocompatibility of hydroxyapatite composite (hydroxyapatite, plaster of Paris, and chitosan) impregnated with gentamicin, fosfomycin, imipenem, or amphotericin B. METHODS: The interactions of the extract from each drug against osteoblast were tested using the methylthiotetrazole test. RESULTS: Extracts from all drugs showed good biocompatibility at concentrations varying from 10 microgram/ml to 1000 microgram/ml. Imipenem and amphotericin B at a concentration of 1000 microgram/ml had a significantly higher percentage of cell viability than the control group. No morphological change of osteoblast was observed in all drug tests at any concentrations. CONCLUSION: The hydroxyapatite composite had a good biocompatibility for carrying gentamicin, fosfomycin, imipenem, or amphotericin B.

Misdiagnosis in vertebral osteomyelitis: problems and factors.

One hundred and one cases diagnosed with vertebral osteomyelitis were evaluated for misdiagnosis and both factors and outcomes of misdiagnosis were assessed. There were 67 patients with tuberculous spondylitis and 34 patients with pyogenic vertebral osteomyelitis. Misdiagnosis occurred in 33.7 per cent of the cases. The average delayed diagnosis time was 2.6 months (range, 0.2 to 12). Age between 60 to 70 years was the most frequent group for misdiagnosis, while the most frequent area of misdiagnosis was the lumbar spine. Metastatic carcinoma, spinal stenosis, herniated nucleus palposus and back strain were common initial misdiagnoses. The factors, age group, absence of fever and positive straight leg raising test (SLRT) were associated with misdiagnosis in univariate analysis and multivariate analysis (odds ratio 3.40 (95%CI:1.07-11.94), 3.47 (95%CI:1.20-10.05), and 24.47 (95%CI:2.18-274.28), respectively) Misdiagnosis was statistically significantly associated with the result of treatment. This paper emphasizes that the elderly age group, absence of fever and positive SLRT are the independent factors which increase the risk of misdiagnosis of vertebral osteomyelitis.

Clinical manifestation of tuberculous and pyogenic spine infection.

The authors compared clinical and baseline parameters between patients with tuberculous spondylitis (67 patients) and pyogenic vertebral osteomyelitis (34 patients). The average age was 50.8 (range, 1 to 82 years). Males were slightly more predominant in both pyogenic and tuberculous infections. Seventy per cent of patients with pyogenic infection had had symptoms for less than 3 months, while this was the case for only 44 per cent of the tuberculous patients. Lumbar spine was the most common site of involvement. Associated infections were more commonly found in tuberculous infection. Thirty per cent of tuberculous spondylitic patients were initially misdiagnosed, while 44 per cent of patients with pyogenic vertebral osteomyelitis had delayed diagnosis. Only 20 per cent and 30 per cent of tuberculous and pyogenic patients had fever, respectively. Neurological deficit occurred more frequently in pyogenic than in tuberculous infection (79% vs 59%), while bowel bladder involvement was more commonly found in tuberculous spondylitis. Kyphosis was significantly more common in tuberculosis than in pyogenic infection (50.8% vs 26.5%, respectively). Sinus tract formation, subcutaneous abscess formation and positive for SLRT (straight-leg-raising test) were found in only a small percentage of the patients. Duration of symptoms, site, associated infection, kyphosis and neurological deficit could be used for differentiation of spinal infection.

Use of growth factors to improve muscle healing after strain injury.

Muscle injuries represent a large number of professional and recreational sports injuries. Muscle strains habitually occur after an eccentric contraction, which often leads to an injury located in the myotendinous junction. Treatment varies widely, depending on the severity of the trauma, but has remained limited mostly to rest, ice, compression, elevation, antiinflammatory drugs, and mobilization. The authors' research group aims to develop new biologic approaches to improve muscle healing after injuries, including muscle strains. To achieve this goal, the authors investigated several parameters that will lead to the development of new strategies to enhance muscle healing. The authors first evaluated natural muscle healing after strain injuries and showed that muscle regeneration occurs in the early phase of healing but becomes impaired with time by the development of tissue fibrosis. Several growth factors capable of improving muscle regeneration were investigated; basic fibroblast growth factor, insulin-like growth factor, and nerve growth factors were identified as substances capable of enhancing muscle regeneration and improving muscle force in the strained injured muscle. The current study should aid in the development of strategies to promote efficient muscle healing and complete recovery after strain injury.

Development of approaches to improve the healing following muscle contusion.

Muscle injuries are a challenging problem in traumatology, and the most frequent occurrence in sports medicine. Muscle contusions are among the most common muscle injuries. Although this injury is capable of healing, an incomplete functional recovery often occurs, depending on the severity of the blunt trauma. We have developed an animal model of muscle contusion in mice (high energy blunt trauma) and characterized the muscle's ability to heal following this injury using histology and immunohistochemistry to determine the level of muscle regeneration and the development of scar tissue. We have observed a massive muscle regeneration occurring in the first 2 wk postinjury that is subsequently followed by the development of muscle fibrosis. Based on these observations, we propose that the enhancement of muscle growth and regeneration, as well as the prevention of fibrotic development, could be used as approach(es) to improve the healing of muscle injuries. In fact, we have identified three growth factors (bFGF, IGF-1, and NGF) capable of enhancing myoblast proliferation and differentiation in vitro and improving the healing of the injured muscle in vivo. Furthermore, the ability of adenovirus to mediate direct and ex vivo gene transfer of beta-galactosidase into the injured site opens possibilities of delivering an efficient and persistent expression of these growth factors in the injured muscle. These studies should help in the development of strategies to promote efficient muscle healing with complete functional recovery following muscle contusion.