Bone Density by Specific Anatomic Location Using Hounsfield Samples of the Lower Extremity: A Multi-center Retrospective Analysis

Biomechanical analysis of a magnesium plantar plate prototype system for the first tarsometatarsal joint fusion: a cadaveric study

BACKGROUND

Titanium plantar plates have proven successful in the fixation of the first tarsometatarsal arthrodesis (TMT). However, a second surgery is typically needed for implant removal, and potential adverse effects, carried by the conventional implantations, are not uncommon. The purpose of this study was to determine whether a novel magnesium-based plantar plate system provides similar fusion stability to a titanium-based plantar plate system under various loading conditions.

METHODS

Six matched-pair human cadaveric specimens underwent TMT fusions using either a magnesium plantar plate system prototype or a titanium plantar plate system. Specimens were cyclically loaded with a force ranging from 5 N to 50 N for 5,000 cycles, and displacement was recorded. Axial stiffness (N/mm) was calculated from load-displacement curves. Each specimen was loaded to failure at a rate of 5 mm/min, and the ultimate load was recorded.

RESULTS

No significant difference was found in the vertical displacement between Ti group and Mg group after 100 cycles (2.4 ± 1.0 mm vs. 1.3 ± 1.4 mm, p = 0.196), 500 cycles (3.3 ± 1.3 mm vs. 1.7 ± 1.7 mm, p = 0.142), 1,000 cycles (3.7 ± 1.5 mm vs. 1.9 ± 1.9 mm, p = 0.128), 2,500 cycles (4.2 ± 1.7 mm vs. 2.3 ± 2.2 mm, p = 0.172) and 5,000 cycles (4.5 ± 1.8 mm vs. 2.3 ± 3.3 mm, p = 0.125), Additionally, no significant differences were observed in initial stiffness (53.1 ± 19.2 N/mm vs. 82.2 ± 53.9 N/mm, p = 0.257), final stiffness (90.6 ± 48.9 N/mm vs. 120.0 ± 48.3 N/mm, p = 0.319), or maximum load-to-failure (259.8 ± 98.2 N vs. 323.9 ± 134.9 N, p = 0.369).

CONCLUSIONS

Based on the performed biomechanical testing, the magnesium plantar plate system provides mechanical stability equivalent to the titanium plantar plate system in fixation for the first TMT joint fusion.

Quantitative Volumetric Measurements of Bone Grafting Sites Within the Lower Extremity on Computed Tomography Scans

The anterior iliac crest is one of the most used options; however, pain and other complications have been reported. Other options for bone harvest in the lower extremity, such as the proximal tibia and calcaneus, can be useful sites for bone grafting. Computed tomography angiography images of the lower extremity were analyzed using 3-D Slicer™ medical imaging software, creating an advanced 3-dimensional model. Bone volume (cm3) and bone mineral density (Hounsfield units) were measured from the cancellous bone in the anterior iliac crest, posterior iliac crest, proximal tibia, and the calcaneus. Fifteen studies were included. The total volume measured it was of 61.88 ± 14.15 cm3, 19.35 ± 4.16 cm3, 32.48 ± 7.49 cm3, 26.40 ± 7.18 cm3, for the proximal tibia, anterior and posterior iliac crest, and calcaneus, respectively. Regarding Hounsfield units, the densities were 116 ± 58.77, 232.4 ± 68.65, 214.4 ± 74.45, 170.5 ± 52.32, for proximal tibia, anterior and posterior iliac crest, and calcaneus. The intraclass correlation coefficients were in average >0.94. In conclusion, the proximal tibia has more cancellous bone than the anterior and posterior iliac crest. The calcaneus has more cancellous bone than the anterior iliac crest. Bone mineral density was highest in the anterior iliac crest and in proximal tibia was the lowest value.

Rate of tarsal and metatarsal bone mineral density change in adults with diabetes mellitus and peripheral neuropathy: a longitudinal study

BACKGROUND

In people with diabetes (DM) and peripheral neuropathy (PN), loss of bone mineral density (BMD) in the tarsals and metatarsals contribute to foot complications; however, changes in BMD of the calcaneal bone is most commonly reported. This study reports rate of change in BMD of all the individual bones in the foot, in participants with DM and PN. Our aim was to investigate whether the rate of BMD change is similar across all the bones of the foot.

METHODS

Participants with DM and PN (n = 60) were included in this longitudinal cohort study. Rate of BMD change of individual bones was monitored using computed tomography at baseline and 6 months, 18 months, and 3-4 years from baseline. Personal factors (age, sex, medication use, step count, sedentary time, and PN severity) were assessed. A random coefficient model estimated rate of change of BMD in all bones and Pearson correlation tested relationships between personal factor variables and rate of BMD change.

RESULTS

Mean and calcaneal BMD decreased over the study period (p < 0.05). Individual tarsal and metatarsal bones present a range of rate of BMD change (-0.3 to -0.9%/year) but were not significantly different than calcaneal BMD change. Only age showed significant correlation with BMD and rate of BMD change.

CONCLUSION

The rate of BMD change did not significantly differ across different foot bones at the group level in people with DM and PN without foot deformity. Asymmetric BMD loss between individual bones of the foot and aging may be indicators of pathologic changes and require further investigation.

TRIAL REGISTRATION

Metatarsal Phalangeal Joint Deformity Progression-R01. Registered 25 November 2015, https://clinicaltrials.gov/ct2/show/NCT02616263.