Are subject-specific models necessary to predict patellar tendon fatigue life? A finite element modelling study.

Patellar tendinopathy is an overuse injury that occurs from repetitive loading of the patellar tendon in a scenario resembling that of mechanical fatigue. As such, fatigue-life estimates provide a quantifiable approach to assess tendinopathy risk and may be tabulated using nominal strain (NS) or finite element (FE) models with varied subject-specificity. We compared patellar tendon fatigue-life estimates from NS and FE models of twenty-nine athletes performing countermovement jumps with subject-specific versus generic geometry and material properties.

Effect of Knee Angle and Quadriceps Muscle Force on Shear-Wave Elastography Measurements at the Patellar Tendon.

Shear-wave elastography (SWE) is a non-invasive imaging technique that provides estimates of tissue stiffness via shear-wave speed measurements. No standardized protocol currently exists for SWE of the patellar tendon, which may be influenced by knee angle and quadriceps muscle force. In this study, the reliability of SWE in cadaveric patellar tendons was examined at three knee angles (0°, 30° and 60°) and three quadriceps muscle forces (0, 50 and 100 N).

Effects of cyclic loading on the mechanical properties and failure of human patellar tendon.

Patellar tendinopathy is a common overuse injury in sports such as volleyball, basketball, and long-distance running. Microdamage accumulation, in response to repetitive loading of the tendon, plays an important role in the pathophysiology of patellar tendinopathy. This damage presents mechanically as a reduction in Young's modulus and an increase in residual strain.

Validation of Bone Density and Microarchitecture Measurements of the Load-Bearing Femur in the Human Knee Obtained Using In Vivo HR-pQCT Protocol.

High resolution peripheral quantitative computed tomography (HR-pQCT) was designed to study bone mineral density (BMD) and microarchitecture in peripheral sites at the distal radius and tibia. With the introduction of the second generation HR-pQCT scanner (XtremeCT II, Scanco Medical) that has a larger, longer gantry it is now possible to study the human knee in vivo using HR-pQCT. Previous validation of HR-pQCT measurements at the distal radius and tibia against micro-CT is not representative of the knee because the increased cross-sectional area, greater amount of soft tissue surrounding the scan region, and different imaging protocol result in potentially increased beam hardening effects and photon scatter and different signal-to-noise ratio.

A biomechanical study of clamping technique on patellar tendon surface strain and material properties using digital image correlation.

Several clamping techniques exist for ex vivo mechanical testing of tendon. For the patellar tendon, one can choose to clamp directly to the bony attachment sites, the tendon itself, or a combination of the two; however, the influence of these techniques on localized strains and gross material properties is unknown. To this end, uniaxial tensile tests were performed on eleven porcine patellar tendons in three clamping setups while digital image correlation was used to measure axial and transverse strains, Young's modulus, and Poisson's ratio.

The Effects of Increased Midsole Bending Stiffness of Sport Shoes on Muscle-Tendon Unit Shortening and Shortening Velocity: a Randomised Crossover Trial in Recreational Male Runners.

Background: Individual compliances of the foot-shoe interface have been suggested to store and release elastic strain energy via ligamentous and tendinous structures or by increased midsole bending stiffness (MBS), compression stiffness, and resilience of running shoes. It is unknown, however, how these compliances interact with each other when the MBS of a running shoe is increased. The purpose of this study was to investigate how structures of the foot-shoe interface are influenced during running by changes to the MBS of sport shoes.

Cumulative Metrics of Tendon Load and Damage Vary Discordantly with Running Speed.

Purpose: Cumulative load has become a popular metric in running biomechanics research to account for potential spatiotemporal changes associated with different locomotion strategies. This study investigated how incorporating mechanical fatigue principles into Achilles tendon cumulative load measurements affected their relationship with running speed.

Methods: Achilles tendon forces and strains were estimated from a dynamometry/ultrasound session followed by a motion capture session, where participants ran at three speeds.

Does increased midsole bending stiffness of sport shoes redistribute lower limb joint work during running?

Objectives: To investigate if lower limb joint work is redistributed when running in a shoe with increased midsole bending stiffness compared to a control shoe.

Design: Within-subject with two conditions: (1) commercially available running shoe and (2) the same shoe with carbon fibre inserts to increase midsole bending stiffness.

Methods: Thirteen male, recreational runners ran on an instrumented treadmill at 3.

Effect of Shoe and Surface Stiffness on Lower Limb Tendon Strain in Jumping.

Background: Tendinopathies are painful overuse injuries observed in athletes participating in jumping sports. These injuries are heavily dependent on the resulting strain from the applied mechanical load. Therefore, mechanisms to reduce tendon strain may represent a primary prevention strategy to reduce the incidence of tendinopathy.

Joint kinematics and ground reaction forces in overground versus treadmill graded running.

Background: Treadmills are often used to assess running biomechanics, however the validity of applying results from treadmill graded running to overground graded running is currently unknown.

Research Question: The purpose of this study was to investigate whether treadmill and overground graded running have comparable kinematics and ground reaction force parameters.

Methods: Eleven healthy male adults ran overground and on an instrumented treadmill as motion capture and force platform data were collected for the following conditions: downhill running at a slope of -8° at 10, 13 and 16 km⋅h; level running at 10 and 13 km⋅h; uphill running at a slope of +8° at 8, 10 and 13 km⋅h.

Effects of footwear and stride length on metatarsal strains and failure in running.

Background: The metatarsal bones of the foot are particularly susceptible to stress fracture owing to the high strains they experience during the stance phase of running. Shoe cushioning and stride length reduction represent two potential interventions to decrease metatarsal strain and thus stress fracture risk.

Methods: Fourteen male recreational runners ran overground at a 5-km pace while motion capture and plantar pressure data were collected during four experimental conditions: traditional shoe at preferred and 90% preferred stride length, and minimalist shoe at preferred and 90% preferred stride length.

The influence of minimalist footwear and stride length reduction on lower-extremity running mechanics and cumulative loading.

Objectives: To examine the effects of shoe type and stride length reduction on lower-extremity running mechanics and cumulative loading.

Design: Within-subject with four conditions: (1) control shoe at preferred stride length; (2) control shoe at 90% preferred stride length; (3) minimalist shoe at preferred stride length; (4) minimalist shoe at 90% preferred stride length.

Methods: Fourteen young healthy males ran overground at their preferred speed while motion capture, force platform, and plantar pressure data were collected.