To compare the microstructure, bone quality, and the combination and penetration of cement-bone interface in tissue specimens from patients with osteoarthritis (OA) and rheumatoid arthritis (RA).A total of 80 femoral condyle tissue specimens from 20 OA patients (40 condyles) and 20 RA patients (40 condyles) who underwent total knee arthroplasty at the Department of Orthopaedics in Tengzhou Central People's Hospital were collected between January 2017 and September 2017. According to the random number table method, 20 specimens from the OA group were defined as group A, and 20 specimens in the RA group were defined as group B. The bone quality parameters were measured by micro-CT. The remaining 20 specimens in the OA group and the remaining 20 specimens in the RA group were defined as group C and group D, the cement-bone interfaces were established by the self-made bone cement compression device, and were analyzed by micro-CT.Micro-CT measurement revealed that the bone volume fraction (BV/TV), trabecular thickness (Tb.Th), and trabecular number (Tb.N) in group A were significantly higher than those in group B (all P < .05). The bone surface/bone volume (BS/BV), structure model index (SMI), trabecular separation (Tb.Sp), and degree of anisotropy (DA) in group A were significantly lower than those in group B (all P < .05). The penetration depth of bone cement in group D was significantly greater than those in group C via x-ray detection.The bone quality of OA patients is better than that of RA patients, but the combination and penetration of cement-bone interface of RA patients are better than that of OA patients. The findings advance our understanding of knee prosthesis and have important clinical implications, but they require validations in future studies with larger sample sizes.

Because burst fractures often involve damage to the column and posterior structures of the spine, the fracture block may invade the spinal canal and compress the spinal cord or the cauda equina, causing corresponding neurological dysfunction. When a thoracolumbar burst fracture is accompanied by the presence of bone in the spinal canal, whether posterior surgery requires spinal canal incision decompression is still controversial. Computed tomography images of the thoracolumbar spine of a 31-year-old male with an L1 burst fracture and Mimics 10.0 were used to establish a three-dimensional fracture model for simulating the indirect reduction process. The model was imported into Ansys 10.0 (ANSYS, Inc., Canonsburg, PA), and a 1 to 10 mm displacement was loaded 10° behind the Z-axis on the upper endplate of the L1 vertebral body to simulate position reduction and open reduction. The displacement and stress changes in the intervertebral disc, fractured vertebral body and posterior longitudinal ligament were observed during reduction. Under a displacement loaded 10° behind the Z-axis, the maximum stress in the vertebral body was concentrated on the upper disc of the injured vertebrae. The maximum displacement was in the anterior edge of the vertebral body of the injured vertebrae, and the vertebral body height and the anterior lobes were essentially restored. When the displacement load was applied in the positive Z-axis direction, the maximum displacement was in the posterior longitudinal ligament behind the injured vertebrae. Under a 6 mm load, the posterior longitudinal ligament displacement was 11.3 mm. Under an 8 mm load, this displacement significantly increased to 15.0 mm, and the vertebral stress was not concentrated on the intervertebral disc. A reduction in the thoracolumbar burst fractures by positioning and distraction allowed the injured vertebrae to be restored to normal height and kyphosis. The reduction in the posterior longitudinal ligament can push the bone block in the spinal canal into the reset space and achieve a good reset.

Background: Because burst fractures often involve damage to the column and posterior structures of the spine, the fracture block may invade the spinal canal and compress the spinal cord or the cauda equina, causing corresponding neurological dysfunction. When a thoracolumbar burst fracture is accompanied by the presence of bone in the spinal canal, whether posterior surgery requires spinal canal incision decompression remains controversial.Methods: Computed tomography (CT) images of the thoracolumbar spine of a 31-year-old male with an L1 burst fracture and Mimics 10.0 were used to establish a three-dimensional fracture model for simulating the indirect reduction process. The model was imported into Ansys 10.0, and a 1-10 mm displacement was loaded 10° behind the Z-axis on the upper endplate of the L1 vertebral body to simulate position reduction and open reduction. The displacement and stress changes in the intervertebral disc, fractured vertebral body and posterior longitudinal ligament were observed during reduction.Results: Under a displacement loaded 10° behind the Z-axis, the maximum stress in the vertebral body was concentrated on the upper disc of the injured vertebrae. The maximum displacement corresponded to the anterior edge of the vertebral body of the injured vertebrae, and the vertebral body height and the anterior lobes were essentially restored. When the displacement load was applied in the positive Z-axis direction, the maximum displacement corresponded to the posterior longitudinal ligament behind the injured vertebrae. Under a 6 mm load, the posterior longitudinal ligament displacement was 11.3 mm. Under an 8 mm load, this displacement significantly increased to 15.0 mm, and the vertebral stress was not concentrated on the intervertebral disc.Conclusions: The reduction of thoracolumbar burst fractures by positioning and distraction allowed the injured vertebrae to be restored to the normal height and kyphotic angle. The reduction of the posterior longitudinal ligament can move the bone block in the spinal canal into the reset space and yield good reset results.