Performance of modified anatomic plates is comparable to proximal femoral nail, dynamic hip screw and anatomic plates: finite element and biomechanical testing.

AIM: To establish whether the modified anatomic plate (MAP) performs as well as the anatomic plate (AP), dynamic hip screw (DHS) and proximal femoral nail (PFN) from a biomechanical perspective. MATERIALS AND METHODS: The, AP, MAP, DHS and PFN were assessed using finite element (FE) methods and biomechanical tests. A solid model was created based on the fracture lines and results were assessed using analyses of variance. MAIN OUTCOME MEASUREMENTS: Independent variables were the implants (n=4) and axial loads: 0-1000 Newton (N) in 100 N increments. Dependent variables were loads at the intertrochanteric fracture line as measured by load cells. RESULTS: Axial loads ≤400 N generated significantly (p<0.05) greater stress at the fracture line in both the FE model and biomechanical settings: the PFN generated the highest forces at the fracture line followed by the AP, MAP and DHS. For axial loads ≥400 N, the AP and DHS generated nonsignificant (p>0.5) lower forces (almost 50% less) compared with the MAP and PFN. At 1000 N, the DHS generated the highest (p<0.05) load at the fracture line. CONCLUSION: The biomechanical features of the MAP were similar to those of the PFN. The MAP generated optimal loads at both the fracture site and the proximal femur. FE methods and biomechanical tests revealed that the MAP is associated with both intra- and extra-medullary fixation features, even though the load was applied as an extramedullary stimulus.

The effect of prophylactic dose of a low molecular weight heparin on skin wound healing of rats.

PURPOSE: To investigate the effect of prophylactic dose of a low molecular weight heparin, enoxaparin, on skin wound healing of rats. METHODS: Forty rats were used for the study. Rats were randomly assigned to two equal groups. Experimental group received prophylactic dose of enoxaparin. Physiologic saline was administered to the control group. Parameters of wound healing of experimental and control groups were compared. For comparison of the groups in terms of fibrosis, vascularization, inflammation, epithelization, and tensile strength test (Newton). Mann-Whitney-U test was used because variables were categorical data (fibrosis, vascularization, inflammation and epithelization). Differences between groups were analyzed with independent samples t-test (tensile strength). Significance was set at p<0.05. RESULTS: Skin wound of the experimental group presented tensile strength significantly decreased (p<0.001), histopathologic examination revealed a significant (p<0.001) delayed epithelization and decreased in fibrosis, vascularization, inflammation (p<0.001) in the experimental group. CONCLUSION: Enoxaparin delay wound healing by decreased inflammatory cells, fibroblast contents and their products (growth factors), and by promoted hemorrhage.

The effect of prophylactic dose of a low molecular weight heparin on skin wound healing of rats / Efeito da dose profilática de heparina de baixo peso molecular na cicatrização de feridas na pele de ratos

PURPOSE: To investigate the effect of prophylactic dose of a low molecular weight heparin, enoxaparin, on skin wound healing of rats. METHODS: Forty rats were used for the study. Rats were randomly assigned to two equal groups. Experimental group received prophylactic dose of enoxaparin. Physiologic saline was administered to the control group. Parameters of wound healing of experimental and control groups were compared. For comparison of the groups in terms of fibrosis, vascularization, inflammation, epithelization, and tensile strength test (Newton). Mann-Whitney-U test was used because variables were categorical data (fibrosis, vascularization, inflammation and epithelization). Differences between groups were analyzed with independent samples t-test (tensile strength). Significance was set at p<0.05. RESULTS: Skin wound of the experimental group presented tensile strength significantly decreased (p<0.001), histopathologic examination revealed a significant (p<0.001) delayed epithelization and decreased in fibrosis, vascularization, inflammation (p<0.001) in the experimental group. CONCLUSION: Enoxaparin delay wound healing by decreased inflammatory cells, fibroblast contents and their products (growth factors), and by promoted hemorrhage.

OBJETIVO: Investigar o efeito de dose profilática da heparina de baixo peso molecular, enoxaparina, na cicatrização de feridas na pele de ratos. MÉTODOS: Quarenta ratos foram utilizados para o estudo. Ratos foram distribuídos aleatoriamente a dois grupos iguais. O grupo experimental recebeu profilática de enoxaparina. Solução salina fisiologica foi administrada ao grupo controle. Foram comparados parâmetros de cicatrização dos grupos experimental e controle.Os grupos foram comparados em termos de fibrose, vascularização, inflamação, epitelização e força tensil (teste de Newton). Foi realizado o teste de Mann-Whitney-U para variáveis com dados categóricos (fibrose, cicatrização, inflamação e epitelização). Diferenças entre os grupos foram analisadas como amostras independentes pelo t-teste (força tensil). Significância foi fixada para p < 0,05. RESULTADOS: A ferida do grupo experimental apresentou força tensil diminuída significativamente (p < 0,001), o exame histopatológico revelou um significativo (p < 0,001) retardo na epitelização e diminuição na fibrose, cicatrização, inflamação (p < 0,001) no grupo experimental. CONCLUSÃO: A enoxaparina retarda a cicatrização da ferida pela diminuição das células inflamatórias, pelo menor conteúdo de fibroblasto e seus produtos (fatores de crescimento) e por promover hemorragia. O grupo experimental foi incluído pela perda significativa da força tênsil no presente estudo.

Lengthening procedures of small bones of foot and foot stump.

Foot length discrepancy may result from congenital or acquired causes. If the absence of the foot is more proximal than the metatarsal level, push off and foot resilience will be disturbed and rapid walking and spring will be awkward. Those patients have to be fitted with a prosthesis extending above the ankle to the distal leg. The functional impairment and poor cosmetic appearance become social problems especially for adolescents. Twelve cases underwent a lengthening procedure of small bones of the foot in our clinic since 1995 to lengthen the foot or a foot stump. Results were satisfactory.

Age-related changes in human tendo calcaneus collagen fibrils.

OBJECTIVE: The ruptures of tendo calcaneus often occur between the age of 30-45 years as described by several textbooks. It is also described that some diseases and drugs are said to be responsible in the etiology; however, there are no studies related with the detailed histological structure of collagen fibrils found in the tendon in the age groups of humans. In view thereof, this study was aimed to obtain further information on the etiology and to find an answer regarding the frequency of the ruptures occurring between the age of 30-45 years in humans. METHODS: In the study, the biopsy specimens taken from 28 patients (ages 1-68 year) who had undergone surgery due to tendo calcaneus ruptures or achilloplasty operation were examined by transmission electron microscope. All the specimens were prepared according to routine electron microscopic tissue preparation technique. The patients were divided into 7 age groups (1-9, 10-19, 20-29, 30-39, 40-49, 50-59, >60 years) and there were 4 patients in each group. The transverse diameters of collagen fibers were measured from the ultra thin sections and statistical analysis of the results were performed. The study was carried out in the electron microscopy laboratory of the Anatomy Department of Hacettepe University, Ankara, Turkey between January 2004 and September 2004. RESULTS: The diameters of the collagen fibers were higher in the 20-29 year-old group compared to other groups and it showed a statistically significant difference. In patients who were in the 30-39 year-old group or older, the diameters of the collagen fibers were lesser than the 20-29 year-old group. However, an increase was observed in the collagen fibril concentration of these groups. In examination of the specimens of patients who were under 20-year-old, the diameter of the collagen fibers were less than the 20-29 year-old group. The electron microscopic appearance of the tissue sample of a one-year-old patient had a specific organization and in this patient, both the diameters and concentration of collagen fibers were less. CONCLUSION: We believe that the decrease in the diameters of collagen fibers of 30-45 year-old patients who are in the active period of their life, can play a role in the etiology of the frequency of tendo calcaneus ruptures similar to other etiologic factors.