Age-related changes in bone loss and trabecular microstructure within the male proximal femur are not uniform in this cadaveric population.

No abstract

The appearance of the 'grand-piano sign' on the anterior resected surface of the femur has been considered to be a marker for correct femoral rotational alignment during total knee replacement. Our study was undertaken to assess quantitatively the morphological patterns on the resected surface after anterior femoral resection with various angles of external rotation, using a computer-simulation technique. A total of 50 right distal femora with varus osteoarthritis in 50 Korean patients were scanned using computerised tomography. Computer image software was used to simulate the anterior femoral cut, which was applied at an external rotation of 0 degrees, 3 degrees and 6 degrees relative to the posterior condylar axis, and parallel to the surgical and clinical epicondylar axes in each case. The morphological patterns on the resected surface were quantified and classified as the 'grand-piano sign', 'the boot sign' and the 'butterfly sign'. The surgeon can use the analogy of these quantified sign patterns to ensure that a correct rotational alignment has been obtained intra-operatively.

The concept of lose, restore, maintain (LRM) for reversing existing osteoporosis was tested in rats. The withdrawal of PTH results in the loss of the acquired bone mass, but sequential therapy with zoledronate quite effectively maintained the PTH(1-84)-acquired bone quantity and quality.Introduction: Because antiresorptive agents against osteoporosis are presently quite limited, strong anabolic agents such as human parathyroid hormone (hPTH) are quite helpful. However, because hPTH(1-34) is available only through injection and has a critical side effect of causing bone tumors during life-long administration in the rat, it would be practical to use PTH for the shortest possible duration to obtain the maximal effect. To determine the effectiveness of the osteoporosis-reversing concept of lose, restore, and maintain (LRM), recombinant hPTH(1-84) ] and the respective antiresorptive agents were sequentially studied. Materials and Methods: Thirty-six, 20-week-old Sprague-Dawley rats were used. Treatment started at the 25th week after ovariectomy, which was performed at 20 weeks of age, with 5 weeks of rhPTH(1-84) 100 g/kg/day, 5 days/week, followed by the respective sequential therapies for 5 weeks as follows: (1) ovariectomized rats (OVX; n ϭ 6), (2) sham-operated rats (SHAM; n ϭ 6), (3) OVX rats with PTH maintenance (PTH-M; n ϭ 6), (4) OVX rats treated with PTH and then PTH was withdrawn (PTH-W; n ϭ 6), (5) PTH-treated OVX rats treated with 17␤-estradiol (PTH-E; 10 g/day SC, 5 days/week; n ϭ 6), and (6) PTH-treated OVX rats treated with zoledronate (PTH-Z; 12.5 g/kg SC weekly; n ϭ 6). BMD of the right femora was measured by DXA. CT was used to measure the structural parameters of the second lumbar vertebrae. Three-point bending test of the femora and compressive tests of vertebrae were also performed. Results: Bone quantity data showed that the BMD and most of the microstructural parameters were significantly higher in the PTH-M and PTH-Z groups than in the OVX and PTH-W groups (p Ͻ 0.05). Measurement of the cortical thickness revealed that only the PTH-M group showed a significant increase (p ϭ 0.001). The ultimate force (F u ) at the midshaft of the femora was similar in the treated groups and stronger than in the OVX group (p Ͻ 0.05). However, in the vertebrae, the F u of the PTH-M and PTH-Z groups was significantly higher, by ϳ44 -47%, than in the OVX and PTH-E groups and showed a higher tendency than in the PTH-W group. Conclusion: PTH withdrawal resulted in the loss of acquired BMD, and sequential therapy with antiresorptives prevented further loss (17␤-estradiol versus zoledronate). The zoledronate after rhPTH(1-84) as a sequential regimen was quite consistently effective.

Intervertebral disc spacers using bioactive ceramics have been used to treat degenerative spinal disease. Tooth-shaped spacers are commonly used to prevent migration, but there is a possibility of fracture when inserted or after insertion. Intervertebral disc spacers with either an isosceles triangle-shaped tooth (T1) or a right triangle-shaped tooth (T2) were used as a control group. The design factors for the experimental group were modified to prevent fractures induced by stress concentration, and the surfaces of the spacers were designed as either an isosceles triangle-shaped valley (V1) or a right triangle-shaped valley (V2). Linear analysis using finite element model (FEM) was performed, and Von Mises stress distribution was calculated by applying 1000 N of uniformly distributed load. Samples of the V2 design were made with bioactive glass-ceramics (BGS-7) and evaluated for compressive strength, fatigue degree, and impact strength. Von Mises stress was highest at the first tooth from the posterior side for the control group and at the center for the experimental group. Compared with the control group, the experimental group showed 18.4% and 82.5% reduction (V1 vs. T1 and V2 vs. T2, respectively) in the maximum stress at the bottom of the valleys. The FEM analysis revealed that the V2 design had the most even load distribution. The V2 samples with bioactive glass-ceramics were evaluated for compressive strength, and all six samples were not fractured up to 24 000 N. However, the average impact strength was 19.42 kN, suggesting that momentary force caused damage at a lower load than compression with a steady speed. The BGS-7 intervertebral disc spacer with V2 design was not fractured during the fatigue test at maximum pressure of 8000 N, R ≥10, 5 Hz, and 5 million cycles. These data confirm that the BGS-7 spacer with the V2 design may be clinically applicable. Collectively, the modified surface geometry of the experimental group significantly lowered Von Mises stress values at the bottom of the valleys, and thus the possibility of fracture by compressive load was greatly reduced. Also, impact during insertion was confirmed to cause fracture more easily, as the impact strength was lower than the compressive strength in the experimental group.