Immediate effect of photobiomodulation therapy on Achilles tendon morphology and mechanical properties: an exploratory study

Objectives

Evaluate the immediate (within 4 hours) effects of laser-induced photobiomodulation (PBM) therapy on Achilles tendon morphology and mechanical properties in healthy and pathologic tendons.

Materials and Methods

Twenty people with healthy Achilles tendons and twelve people with Achilles tendinopathy participated. One Achilles tendon received PBM treatment following an established protocol and the contralateral side received a placebo treatment. Achilles tendon morphology and mechanical properties were evaluated bilaterally with ultrasound imaging and continuous shear wave elastography immediately before treatment, immediately after treatment, then 2- and 4-hours after treatment.

Results

There were no immediate effects of PBM on tendon morphology or mechanical properties when comparing the PBM-treated side and placebo-treated side within each cohort. Additionally, the effects of PBM did not differ between healthy and pathologic Achilles tendons.

Conclusion

When treated with a laser-induced PBM treatment, healthy and pathologic Achilles tendons do not have immediate (within 4 hours) changes in tendon morphology or mechanical properties. These findings suggest that PBM therapy can be administered before other clinical treatments or high-load activities.

Longitudinal and Horizontal Load Testing of Inflatable Penile Implant Cylinders of Two Manufacturers: An Ex Vivo Demonstration of Inflated Rigidity

INTRODUCTION

Since the inception of the inflatable penile prosthesis, a new era has been ushered in for the management of erectile dysfunction. Despite multiple innovations to improve function and reliability, there are no current data comparing the biomechanical properties of these devices.

AIM

To compare the resistance of the Coloplast Titan (Minneapolis, MN, USA) with that of the AMS 700 LGX (Minnetonka, MN, USA) penile prosthesis cylinders to longitudinal (penetration) and horizontal (gravity) forces.

METHODS

We compared two cylinder sizes from each company: the Coloplast Titan (18 and 22 cm) and the AMS 700 LGX (18 and 21 cm). To evaluate axial rigidity, which simulates forces during penetration, we performed a longitudinal load compression test to determine the load required to cause the cylinder to kink. To test horizontal rigidity, which simulates the horizontal forces exerted by gravity, we performed a modified cantilever test and measured the degrees of bend for each device. All devices were tested at 10, 15, and 20 PSI to simulate in vivo pressures.

MAIN OUTCOME MEASURES

The main outcome measurement for the longitudinal load test (penetration) was the force required for the inflated cylinder to bend, thereby affecting its rigidity. The main outcome for the horizontal rigidity test (gravity) was the angle of displacement, in which a smaller angle represents a more horizontally rigid device.

RESULTS

Longitudinal column testing (penetration) demonstrated that less force was required for the AMS device to kink compared with the Coloplast implant across all three fill pressures tested. The Coloplast Titan also had a smaller angle of displacement at the modified cantilever test (gravity) compared with the AMS implant across all fill pressures.

CONCLUSION

The Coloplast Titan demonstrated greater resistance to longitudinal (penetration) and horizontal (gravity) forces in this study. The AMS device was very sensitive to fill pressures. In contrast, the Coloplast Titan's ability to resist these forces was less dependent on the device fill pressure.

Morphologic and biomechanical comparison of spinous processes and ligaments from scoliotic and kyphotic patients

The spinous processes and supraspinous and interspinous ligaments (SSL and ISL, respectively) limit flexion and may relate to spinal curvature. Spinous process angles and mechanical properties of explanted human thoracic posterior SSL/ISL complexes were compared for scoliosis (n=14) vs. kyphosis (n=8) patients. The median thoracic coronal Cobb angle for scoliosis patients was 48°, and sagittal angles for kyphosis patients was 78°. Spinous processes were gripped and four strain steps of 4% were applied and held. Percent relaxation was calculated over each step, equilibrium load data were fit to an exponential equation, and a Kelvin model was fit to the load from all four curves. Failure testing was also performed. Median ligament complex dimensions from scoliosis and kyphosis patients were, respectively: ISL width=16.5mm and 16.0mm; SSL width=4.3mm and 3.8mm; ISL+SSL area=17.2mm and 25.7mm; these differences were not significant. Significant differences did exist in terms of spinous process angle vs. spine axis (47° for scoliosis and 32° for kyphosis) and SSL thickness (2.1mm for scoliosis and 3.0mm for kyphosis). Fourth-step median relaxation was 42% for scoliosis and 49% for kyphosis. Median linear region stiffness was 42N/mm for scoliosis and 51N/mm for kyphosis. Median failure load was 191N for scoliotic and 175N for kyphotic ligaments. Differences in loading, relaxation, viscoelastic and failure parameters were not statistically significant, except for a trend for greater initial rate of relaxation (T1) for scoliosis ligaments. However, we found significant morphological differences related to the spinous processes, which suggests a need for future biomechanical studies related to the musculoskeletal aspects of spinal alignment and posture.

Wear biomechanics in the slicing dentition of the giant horned dinosaur Triceratops

Herbivorous reptiles rarely evolve occluding dentitions that allow for the mastication (chewing) of plant matter. Conversely, most herbivorous mammals have occluding teeth with complex tissue architectures that self-wear to complex morphologies for orally processing plants. Dinosaurs stand out among reptiles in that several lineages acquired the capacity to masticate. In particular, the horned ceratopsian dinosaurs, among the most successful Late Cretaceous dinosaurian lineages, evolved slicing dentitions for the exploitation of tough, bulky plant matter. We show how Triceratops, a 9-m-long ceratopsian, and its relatives evolved teeth that wore during feeding to create fullers (recessed central regions on cutting blades) on the chewing surfaces. This unique morphology served to reduce friction during feeding. It was achieved through the evolution of a complex suite of osseous dental tissues rivaling the complexity of mammalian dentitions. Tribological (wear) properties of the tissues are preserved in ~66-million-year-old teeth, allowing the creation of a sophisticated three-dimensional biomechanical wear model that reveals how the complexes synergistically wore to create these implements. These findings, along with similar discoveries in hadrosaurids (duck-billed dinosaurs), suggest that tissue-mediated changes in dental morphology may have played a major role in the remarkable ecological diversification of these clades and perhaps other dinosaurian clades capable of mastication.