RESUMO
BACKGROUND: Lumbar disc herniation is a common clinical disease, and its pathological basis is disc degeneration. Long-term mechanical load is considered to be an important cause of lumbar disc degeneration. Because the occurrence of lumbar disc herniation is strongly associated with its mechanical state, it is necessary to further study the stress/strain behavior in the lumbar disc to provide inspiration for preventing lumbar disc herniation. OBJECTIVE: To analyze the effect of fatigue loading on mechanical properties of the whole and different regions of the intervertebral disc. METHODS: The freshly slaughtered sheep lumbar intervertebral discs L1-L2, L3-L4, and L5-L6 were obtained and made into experimental samples. The experimental samples were fixed on the experimental platform through the upper and lower vertebrae, and a quasi-static compression-cyclic loading compression-quasi-static compression experiment was performed. The L3-L4 motion segment was cut parallel to the sagittal plane, and the non-contact digital image correlation technique was used to record the internal deformation of the lumbar disc during compression. RESULTS AND CONCLUSION: (1) The results showed that all lumbar intervertebral discs exhibited non-linear load-displacement and stress-strain characteristics. (2) Effect of fatigue loading: The Young’s modulus of the lumbar intervertebral disc increased significantly after fatigue loading. (3) Impact of segment changes: The Young’s modulus changed with segment changes as follows: L5-L6 segments < L3-L4 segments < L1-L2 segments. (3) Effect of loading rate: Comparing the mechanical properties under the compression rate of 0.01 mm/s and 0.1 mm/s, it could be seen that with the increase of the compression rate, the Young’s modulus of the intervertebral disc increased significantly. (5) Internal displacement distribution: Fatigue loading had a significant effect on the internal displacement distribution of the lumbar disc under compression. Before fatigue loading, the axial displacement in upper afferent fiber was largest, and the radial displacement in inner afferent fiber was slightly smaller than that in outer afferent fiber. After fatigue loading, the axial displacement in upper afferent fiber was smallest, and the radial displacement in inner afferent fiber was significantly smaller than in outer afferent fiber. (6) The research work in this article has important theoretical guiding significance for preventing lumbar disc herniation in daily life.
RESUMO
BACKGROUND: A large number of studies in and outside China have confirmed that the occurrence of calcaneus spur is related to plantar fasciitis, osteoarthritis and other diseases. For the etiology of calcaneus spur, two hypotheses have been proposed, which are “vertical compression” and “vertical traction”, but they have not been confirmed. OBJECTIVE: To analyze morphology and location of calcaneal spurs so as to analyze the etiology of calcaneal spurs. METHODS: Totally 831 complete dry calcaneal specimens and 222 cases of X-ray films were randomly selected, including 33 cases aged 18-30 years, 97 cases aged 31-50 years, 83 cases aged 51-70 years, and 9 cases aged 71-90 years. Morphology and location of calcaneal spurs were observed. The length and width of the calcaneal spurs were measured directly by vernier caliper. The length of the calcaneal spurs was measured by using the related software in the calcaneus lateral X-ray film. The implementation of the research program was in line with the ethical requirements of Southern Medical University. The calcaneal specimens used in the experiment were provided by the Department of Anatomy of Southern Medical University and were donated voluntarily by the donors. RESULTS AND CONCLUSION: (1) There were 142 specimens of calcaneal spur in the calcaneal specimens and 82 cases of calcaneal spurs in the lateral X-ray films. The highest point of 88.1% of achilles tendon spurs was in lateral edge of the calcaneus, and the plantar spurs were all located in the medial nodule of the calcaneus. (2) X-ray films showed that the average age of the spur-free population was (42.9±14.2) years, and the average age of the population with spurs was (54.0±13.4) years. The average age of patients with Achilles tendon spur was (42.3±14.9) years. The difference between spur-free population and population with spurs was statistically significant (P 0.05). (3) Calcaneal specimen showed that the shape of Achilles tendon spur was vertical ridge, and the plantar spur was lamellar. (4) Results indicated that the incidence rate of spurs in X-ray films was significantly higher than that in specimens. The calcaneal spur was mainly in lateral edge of the Achilles tendon attachment, and the plantar spurs were all located in the medial nodule of the calcaneus. The incidence of calcaneal spur is different in different age groups, suggesting that the Achilles tendon spur may be caused by longitudinal traction and the plantar spur may be caused by vertical compression.
RESUMO
Pelvic fractures result from high energy trauma and often associated with concomitant injuries. But, vertically unstable pelvic fractures combined with anterior dislocation of the hip is far less common. The traumatic dislocation of the hip is a true orthopedic emergency and it should be considered that a femoral head can be exposed to deteriorized vascularity. We report a case of vertically unstable pelvic fractures combined with traumatic anterior dislocation of the hip joint with the review of the literature.