Objective To investigate the causes and remedial measures of the failure of continuous epidural for labor analgesia. Methods Nine hundred and fifty-two primiparas who received voluntary labor analgesia were selected. They received epidural block in the L2-3 interspace, and epidural catheter was inserted 4 cm into the epidural space. The method of labor analgesia was continuous intravenous injection combined with self controlled analgesia. The visual analogue score (VAS) >5 scores was analgesia failure. Withdrawing the epidural catheter 1 to 2 cm and replacement of the catheter or changing to subarachnoid space combined with epidural block was used to rescue the analgesia failure. The production process progress and satisfaction rate of postpartum 24 h were recorded. Results The analgesia failure was in 144 cases, and the analgesia failure rate was 15.1%(144/952), among which the epidural catheter was inserted into blood vessels in 47 cases, the epidural catheter was blocked by a blood clot in 13 cases, the epidural catheter bent in 9 cases, the unilateral block or partial block was in 31 cases, the epidural catheter migrated in 37 cases, the catheters left the epidural cavity in 5 cases, and dural puncture was in 2 cases. Eighty-seven cases were treated by withdrawing the epidural catheter 1 to 2 cm, 48 cases were treated by replacement of the catheter, and 9 cases were treated by changing to subarachnoid space combined with epidural block. The satisfaction rate of postpartum 24 h was 96.7%(921/952). Conclusions The failure of continuous epidural block for labor analgesia is higher. According to the different causes, the most of the failures could be rescued by withdrawing the epidural catheter 1 to 2 cm, replacement of the catheter or changing to subarachnoid space combined with epidural block.

Objective To measure stress distribution of the main bone architecture of the normal adult cadaveric foot and discuss the effect of plantar ligament injury on stress distribution. Methods Seven fresh adult cadaveric feet were used and 10 strain gauges attached to the bones of the longitudinal foot arch,including the calcaneus,navicular,medial cuneiform,1-5 metatarsal trunk,the distal part of the tibia and fibular,respectively.After the loading Was added to 700 N by almighty test machine,resistance strainmeter was used to measure surface strain of these bones.The results were processed statistically. Results The strain was varied based on different bone segments attached and increased with loading.Tensile force was always found at the medial part of the navicular,the distal part of the tibia and fibular,while the others showed compression all the time.Peak strain was found at calcaneus.followed by the second and third metatarsal.Strain on the surface of the bone segments changed greatly with different ligament injury(P＜0.05).Conclusion The bone surface stress of the longitudinal foot arch changes significantly when the plantar ligament is injured.

ObjectiveTo evaluate the strain of the weight-bearing metatarsal bone. Methods6 fresh-frozen cadaveric lower extremities were dissected to expose the dorsal aspect of metatarsal. Bone segments were clarified for adherence of strain-gauges while feet kept intact. Then vertical downward axial load was exerted to distal tibia at a 2 mm/min velocity, from 0 N to 1200 N with one minute interval of 200 N leveled loading augment each for sampling. Superficial strain of the metatarsal was measured by resistance strainmeter methods. ResultsThe strain increased gradually with axial loading, and compress force was always found at every marked bone. The strain of every marked bone was significantly different at the same loading (P<0.05). As to the strain of the middle of the metatarsal, the sequence was the second metatarsal＞the third metatarsal＞the fourth metatarsal＞the first metatarsal＞the fifth metatarsal. As to the strain of the second metatarsal, the sequence was the middle＞the neck＞the base. ConclusionThe peak strain was found at the middle of the second and third metatarsal with axial loading, which prompts the stress fractures of the second and third metatarsal are most common, especially the middle of the second metatarsal.

To provide a digital simulation platform for foot-ankle biomechanics research, a 3-D finite element model was established through helical CT images under the principle of RE (reverse engineering) and meshed in FEM software. In the process of modeling cartilage, ligaments, tendons and plantar soft tissue, many anatomic data and results of cadaver specimen experiment were referenced; LINE elements and SHELL elements were used skillfully to simplify the model and resemble the physiological state. The model was then validated by specimen experimentation, which was done on seven fresh cadaver foot specimens, and digital speckle correlation method (DSCM) was used to measure their displacements. Upon the comparison with experimentation and others models, this study also testified that the model, of which the plantar fascia is linked to the heads of metatarsus, is more reasonable to clinical application.
Adult ; Biomechanical Phenomena ; Finite Element Analysis ; Foot ; diagnostic imaging ; Humans ; Imaging, Three-Dimensional ; Male ; Models, Anatomic ; Tomography, Spiral Computed