Biomechanical comparison of three different fixation techniques for anterior column posterior hemitransverse acetabular fractures using anterior intrapelvic approach.

OBJECTIVES: The aim of this study was to biomechanically compare three different fixation methods for the fixation of anterior column posterior hemitransverse type acetabular fracture (ACPHT). METHODS: ACPHT fracture models were created on twenty-four foam cortical shell artificial hemipelvis models. Three fixation methods were assessed - Group 1: posterior column lag screws over a suprapectineal plate; Group 2: Posterior column lag screws over a suprapectineal plate and an infrapectineal plate; Group 3: A suprapectineal plate and a vertical infrapectineal plate. Stiffness and displacement amounts of fixation methods under dynamic and static axial loading conditions were measured. RESULTS: In the dynamic and static tests, Group 3 showed the less stable fixation compared to Group 2. There was no statistically significant difference between the stiffness values of the fixation groups. In the static tests, there was no statistically significant difference between Group 1 and 2, although less displacements were obtained in Group 2. CONCLUSIONS: A combination of posterior lag screws over a suprapectineal plate and an infrapectineal plate supporting the pelvic brim along both sides of the linea terminalis resulted in a better fixation construct than a suprapectineal plate accompanying with a vertical infrapectineal plate provide better stability with less fracture displacement.

Histopathologic Analysis of Tamoxifen on Epidural Fibrosis.

BACKGROUND: Epidural fibrosis is a challenging topic in spinal surgery. This phenomenon constitutes one of the main reasons behind postlaminectomy syndrome or failed back surgery syndrome, which leads to persistent back and leg pain in association with compression and/or stretching the nerve root or the dura. The exact mechanism of action in epidural fibrosis is complex and remains uncertain. Excessive deposition of collagen, fibronectin, and dermatan sulfate, known as the "extracellular matrix," and decrease of tissue cellularity results in epidural fibrosis. The most investigated and important actor in epidural fibrosis as well as in other forms of aberrant wound healing is presumed to be transforming growth factor-1ß formation. Tamoxifen (TAM), a synthetic nonsteroidal antiestrogen used in breast cancer, is also effective in inhibiting fibroblast proliferation via downregulation of transforming growth factor-1ß. METHODS: Twenty-four adult male rats were randomly divided into 3 groups. Laminectomy was the sole intervention in the control group. Spongostan was placed in the operation lodge after laminectomy in the second group. In the treatment group, TAM was administrated orally after laminectomy. Epidural fibrosis, dural thickness, inflammatory response, and arachnoidal involvement were evaluated and graded histopathologically. RESULTS: Epidural fibrosis, dural thickness, and inflammatory response in the subjects treated with TAM were significantly less than in the control and Spongostan group and the differences were statistically significant. Although arachnoidal involvement was observed in a subject in the TAM group, the differences between all groups weren't statistically significant. CONCLUSIONS: Tamoxifen reduced epidural fibrosis, dural thickness, and inflammatory response after laminectomy in rats.

Biomechanical comparison of supraacetabular external fixation and anterior pelvic bridge plating.

Unstable pelvic ring injuries are complex and risky injuries due to high morbidity and mortality. Although anterior pelvic external fixator is a suitable method for rapid stabilization of an injured pelvic ring, due to some disadvantages such as high complication rate, nerve damage, and difficulties of patient's mobility and comfort, there has recently been increased searching for alternative methods for stabilization of the pelvic ring. Pubic symphysis zone freely moves in pelvic models. This study aims to evaluate the biomechanical stability of anterior pelvic bridge plating and compare it with supraacetabular external fixators in an untreated unstable pelvic fracture model. Samples were loaded statically with 2-mm/min loading rate in single leg standing position. Maximum load was 2.3 kN. When loading the samples, photographs were taken continuously. Stiffness values were calculated from the load displacement curves. Some reference parameters were described and were measured from unloaded and 2.3-kN-loaded photographs of the test. The mean stiffness values were 491.14 ± 52.22, 478.55 ± 41.44, and 470.25 ± 44.51 N/mm for anterior pelvic bridge plating group, supraacetabular external fixator group, and Control group, respectively. According to the measured parameters from photographs, the mean displacement at the pubic symphysis was 4.7 ± 0.32, 15.8 ± 2.01, and 18.2 ± 0.47 mm for anterior pelvic bridge plating, supraacetabular external fixator, and Control group, respectively. The highest displacement in the pubic symphysis was found in Control group, and minimum displacement was observed in anterior pelvic bridge plating group. When the perpendicular distance between the right and left lower end of ischium was examined, it was observed that displacement was minimum in anterior pelvic bridge plating group compared to other two groups, regarding to the high stability of pubic symphysis. In conclusion, this study revealed superiority of anterior subcutaneous plate fixation with biomechanical results.