Achilles Tendon Loading Research Articles

Development of a Robotic Assembly for Analyzing the Instantaneous Axis of Rotation of the Foot Ankle Complex.

Ankle instantaneous axis of rotation (IAR) measurements represent a more complete parameter for characterizing joint motion. However, few studies have implemented this measurement to study normal, injured, or pathological foot ankle biomechanics. A novel testing protocol was developed to simulate aspects of in vivo foot ankle mechanics during mid-stance gait in a human cadaveric specimen. A lower leg was mounted in a robotic testing platform with the tibia upright and foot flat on the baseplate. Axial tibia loads (ATLs) were controlled as a function of a vertical ground reaction force (vGRF) set at half body weight (356 N) and a 50% vGRF (178 N) Achilles tendon load. Two specimens were repetitively loaded over 10 degrees of dorsiflexion and 20 degrees of plantar flexion. Platform axes were controlled within 2 microns and 0.008 degrees resulting in ATL measurements within ±2 N of target conditions. Mean ATLs and IAR values were not significantly different between cycles of motion, but IAR values were significantly different between dorsiflexion and plantar flexion. A linear regression analysis showed no significant differences between slopes of plantar flexion paths. The customized robotic platform and advanced testing protocol produced repeatable and accurate measurements of the IAR, useful for assessing foot ankle biomechanics under different loading scenarios and foot conditions.

Effects of minimalist and maximalist footwear on Achilles tendon load in recreational runners

The current investigation aimed to comparatively examine the effects of minimalist, maximalist and conventional footwear on Achilles tendon forces (ATF) during running. Twelve male runners (age 23.11±5.01 years, height 1.78±0.10 cm and body mass 77.13±7.89 kg) ran at 4.0 m/s in the three footwear conditions. ATF’s were calculated using Opensim software allowing the magnitudal and temporal aspects of the ATF to be quantified. Differences between footwear were examined using one-way repeated measures ANOVA. The results showed the peak ATF was significantly larger in minimalist footwear (5.97±1.38 body weight (BW)) compared to maximalist (5.07±1.42 BW). In addition it was revealed that ATF per mile was significantly larger in minimalist (492.31±157.72 BW) in comparison to both maximalist (377.31±148.06 BW) and conventional (402.71±125.51 BW) footwear. Given the relationship between high ATF and Achilles tendon degradation, the current investigation indicated that minimalist footwear may increase runners risk for Achilles tendon injury.

Orthotic Heel Wedges Do Not Alter Hindfoot Kinematics and Achilles Tendon Force During Level and Inclined Walking in Healthy Individuals.

Conservative treatments such as in-shoe orthotic heel wedges to treat musculoskeletal injuries are not new. However, weak evidence supporting their use in the management of Achilles tendonitis suggests the mechanism by which these heel wedges works remains poorly understood. It was the aim of this study to test the underlying hypothesis that heel wedges can reduce Achilles tendon load. A musculoskeletal modeling approach was used to quantify changes in lower limb mechanics when walking due to the introduction of 12-mm orthotic heel wedges. Nineteen healthy volunteers walked on an inclinable walkway while optical motion, force plate, and plantar pressure data were recorded. Walking with heel wedges increased ankle dorsiflexion moments and reduced plantar flexion moments; this resulted in increased peak ankle dorsiflexor muscle forces during early stance and reduced tibialis posterior and toe flexor muscle forces during late stance. Heel wedges did not reduce overall Achilles tendon force during any walking condition, but did redistribute load from the medial to lateral triceps surae during inclined walking. These results add to the body of clinical evidence confirming that heel wedges do not reduce Achilles tendon load and our findings provide an explanation as to why this may be the case.

Heterogeneous Loading of the Human Achilles Tendon In Vivo

The free Achilles tendon is considered a homogeneous structure that transmits muscular force in a linear manner. However, the tendon undergoes longitudinal rotation and is separated in mechanically independent segments with distinct mechanical and material tissue properties. The present article examines the hypothesis that the human Achilles tendon is loaded asymmetrically and undergoes heterogeneous deformation during movement.

The effect of front and back squat techniques on peak loads experienced by the Achilles tendon

Background: A primary technique in the discipline of strength and conditioning the squat has two principal ‘back and front’ variants. Despite the physiological and strength benefits of the squat, the propensity for musculoskeletal injury is high. The current investigation examined the influence of the front and back squat variations on the load experienced by the Achilles tendon. Material/Methods: Achilles tendon loads were obtained from eighteen experienced male participants as they completed both back and front squats. Differences between squat conditions were examined using Bonferroni adjusted (p = 0.0125) paired t-tests. Results: The results showed that the peak Achilles tendon load was significantly greater in the back squat (2.67 ±0.74 B.W) condition compared to the front squat (2.37 ±0.69 B.W). Conclusions: Given the proposed relationship between the magnitude of the load experienced by the Achilles tendon and tendon pathology, the back squat appears to place lifters at greater risk from Achilles tendon injury. Therefore, it may be prudent for lifters who are predisposed to Achilles tendon pathology to utilize the front squat in their training.

Effects of conventional and minimalist footwear on patellofemoral and Achilles tendon kinetics during netball specific movements

Netball is a physically demanding sport that is associated with a high incidence of chronic injuries. Currently there is a trend towards the utilisation of minimalist footwear in netball players as opposed to more conventional netball trainers. The current investigation aimed to examine the effects of netball specific and minimalist footwear on patellofemoral and Achilles tendon loads during netball specific motions. Fifteen female netballers performed both run and cut movements when wearing conventional netball footwear and also a minimalist trainer. Kinematics of the lower extremities were quantified using a motion analysis system alongside ground reaction force information which was obtained using a force platform. Patellofemoral force (PTF), patellofemoral pressure (PP) and Achilles tendon forces (ATF) were quantified using predictive methods and examined between footwear using repeated measures ANOVA. The results indicate that patellofemoral loads (run – PTF: netball specific = 5.56 / minimalist = 4.74 body weight (BW); – PP: netball specific = 13.17 / minimalist = 11.89 MPa; cut – PTF: netball specific = 5.65 / minimalist = 4.82 BW; – PP; netball specific = 14.05 / minimalist = 12.88 MPa) were significantly larger in the conventional footwear compared to minimalist in both movements. Achilles tendon forces (run: netball specific = 4.43 / minimalist = 5.47; cut: netball specific = 4.32 / minimalist = 5.29 BW) were however significantly larger in the minimalist compared to the conventional footwear. Taking the proposed association between knee loading and patellofemoral pathology, the risk from knee injuries in netballers may be reduced via minimalist footwear. However, taking into account the equivalent increases in Achilles tendon forces, this may increase the likelihood of overuse Achilles tendon injuries.

Comparison of achilles tendon loading between male and female recreational runners.

Recreational running is an activity with multiple reported health benefits for both sexes, however, chronic injuries caused by excessive and/or repetitive loading of the Achilles tendon are common. Males have been identified as being at an increased risk of suffering an injury to the Achilles tendon and as such, knowledge of differences in loading between the sexes may provide further information to better understand why this is the case. The aim of the current investigation was to determine whether gender differences in the Achilles tendon load exist in recreational runners. Fifteen male (age 26.74 ± 5.52 years, body height 1.80 ± 0.11 m and body mass 74.22 ± 7.27 kg) and fifteen female (age 25.13 ± 6.39 years, body height 1.68 ± 0.12 m and body mass 67.12 ± 9.11 kg) recreational runners volunteered to take part in the current investigation. Participants completed 10 trials running at 4.0 m·s−1 ±5% striking a force platform (1000 Hz) with their right foot. Ankle joint kinematics were synchronously recorded (250 Hz) using an optoelectric motion capture system. Ankle joint kinetics were computed using Newton-Euler inverse-dynamics. Net external ankle joint moments were then calculated. To estimate Achilles tendon kinetics the plantarflexion moment calculated was divided by an estimated Achilles tendon moment arm of 0.05 m. Differences in Achilles tendon kinetics were examined using independent sample t-tests (p<0.05). The results indicate that males were associated with significantly (p<0.05) greater Achilles tendon loads than females. The findings from this study support the notion that male recreational runners may be at greater risk of Achilles tendon pathology.

Influence of running shoes and cross-trainers on Achilles tendon forces during running compared with military boots

Military recruits are known to be susceptible to Achilles tendon pathology. The British Army have introduced footwear models, the PT-03 (cross-trainer) and PT1000 (running shoes), in an attempt to reduce...

Effects of foot orthoses on Achilles tendon load in recreational runners

BackgroundAchilles tendon pathology is a frequently occurring musculoskeletal disorder in runners. Foot orthoses have been shown to reduce the symptoms of pain in runners but their mechanical effects are still not well understood. MethodsThis study aimed to examine differences in Achilles tendon load when running with and without orthotic intervention. Twelve male runners ran at 4.0m·s−1. Ankle joint moments and Achilles tendon forces were compared when running with and without orthotics. FindingsThe results indicate that running with foot orthotics was associated with significant reductions in Achilles tendon load compared to without orthotics. InterpretationIn addition to providing insight into the mechanical effects of orthotics in runners, the current investigation suggests that via reductions in Achilles tendon load, foot orthoses may serve to reduce the incidence of chronic Achilles tendon pathologies in runners.

Running Shoes Increase Achilles Tendon Load in Walking

Footwear remains a prime candidate for the prevention and rehabilitation of Achilles tendinopathy because it is thought to decrease tension in the tendon through elevation of the heel. However, evidence for this effect is equivocal. This study used an acoustic transmission technique to investigate the effect of running shoes on Achilles tendon loading during barefoot and shod walking. Acoustic velocity was measured in the Achilles tendon of 12 recreationally active males (age, 31 ± 9 yr; height, 1.78 ± 0.06 m; weight, 81.0 ± 16.9 kg) during barefoot and shod walking at matched self-selected speed (3.4 ± 0.7 km·h). Standard running shoes incorporating a 10-mm heel offset were used. Vertical ground reaction force and spatiotemporal parameters were determined with an instrumented treadmill. Axial acoustic velocity in the Achilles tendon was measured using a custom-built ultrasonic device. All data were acquired at a rate of 100 Hz during 10 s of steady-state walking. Statistical comparisons between barefoot and shod conditions were made using paired t-tests and repeated-measure ANOVA. Acoustic velocity in the Achilles tendon was highly reproducible and was typified by two maxima (P1, P2) and minima (M1, M2) during walking. Footwear resulted in a significant increase in step length, stance duration, and peak vertical ground reaction force compared with barefoot walking. Peak acoustic velocity in the Achilles tendon (P1, P2) was significantly higher with running shoes. Peak acoustic velocity in the Achilles tendon was higher with footwear, suggesting that standard running shoes with a 10-mm heel offset increase tensile load in the Achilles tendon. Although further research is required, these findings question the therapeutic role of standard running shoes in Achilles tendinopathy.

Effects of barefoot and barefoot inspired footwear on knee and ankle loading during running

BackgroundRecreational runners frequently suffer from chronic pathologies. The knee and ankle have been highlighted as common injury sites. Barefoot and barefoot inspired footwear have been cited as treatment modalities for running injuries as opposed to more conventional running shoes. This investigation examined knee and ankle loading in barefoot and barefoot inspired footwear in relation to conventional running shoes. MethodThirty recreational male runners underwent 3D running analysis at 4.0m·s−1. Joint moments, patellofemoral contact force and pressure and Achilles tendon forces were compared between footwear. FindingsAt the knee the results show that barefoot and barefoot inspired footwear were associated with significant reductions in patellofemoral kinetic parameters. The ankle kinetics indicate that barefoot and barefoot inspired footwear were associated with significant increases in Achilles tendon force compared to conventional shoes. InterpretationBarefoot and barefoot inspired footwear may serve to reduce the incidence of knee injuries in runners although corresponding increases in Achilles tendon loading may induce an injury risk at this tendon.

Rocker shoes reduce Achilles tendon load in running and walking in patients with chronic Achilles tendinopathy

Relative rest and pain relief play an important role in the management of Achilles tendinopathy, and might be achieved by reducing the load on the Achilles tendon. Previous studies have provided evidence that rocker shoes are able to decrease the ankle internal plantar flexion moment in healthy runners during walking and running. Since plantar flexion moment is related to the Achilles tendon loading, rocker shoes might be considered in the conservative management of Achilles tendinopathy. Therefore, the aim of this study was to investigate the biomechanics of running and walking in a group of patients with Achilles tendinopathy wearing standard shoes versus rocker shoes. Cross-over. Thirteen Achilles tendinopathy patients (mean age 48 ± 14.5 years) underwent three-dimensional gait analysis wearing standard running shoes and rocker shoes during running and walking. Surface electromyography of triceps surae and tibialis anterior was recorded simultaneously. Patients had symptoms for an average of 22.5 months (median 11.5 months) and VISA-A scores were 54 ± 16. With the rocker shoes, the peak plantar flexion moment was reduced by 13% in both running (0.28 N m/kg, p<0.001) and walking (0.20 N m/kg, p<0.001). The peak activity of tibialis anterior was increased by 35% (p=0.015) for the rocker shoes in walking. There was no difference between electromyography peak amplitudes of triceps surae between two shoe sessions in both activities. When used by patients with chronic Achilles tendinopathy, rocker shoes cause a significant reduction in plantar flexion moment in the late stance phase of running and walking without substantial adaptations in triceps surae muscular activity.

Gender differences in the Achilles tendon load during the fencing lunge

AbstractRecent epidemiological analyses in fencing have shown that injuries and pain linked specifically to fencing training/competition were evident in 92.8% of fencers. Specifically the prevalence of Achilles tendon pathology has increased substantially in recent years, and males have been identified as being at greater risk of Achilles tendon injury compared to their female counterparts. This study aimed to examine gender differences in Achilles tendon loading during the fencing lunge.Achilles tendon load was obtained from eight male and eight female club level epee fencers using a 3D motion capture system and force platform information as they completed simulated lunges. Independent t-tests were performed on the data to determine whether differences existed.The results show that males were associated with significantly greater Achilles tendon loading rates in comparison to females.This suggests that male fencers may be at greater risk from Achilles tendon pathology as a function of fencing training/ competition.

Talonavicular Joint Fixation

Fusion of the talonavicular (TN) joint is an effective treatment for hindfoot pain and deformity. Nonunion in hindfoot fusion procedures is most common in the TN joint. The purpose of this study was to evaluate and compare the mechanical stability of 2 different forms of fixation for isolated fusion of the TN joint. 13 fresh-frozen cadaver foot and ankles were procured and mounted vertically in a robotic biomechanical testing platform and tested before and after operative fixation; 7 specimens received 2 retrograde lag screws (2S), and 6 specimens received a locked compression plate with 1 retrograde lag screw (PS). A constant Achilles tendon load was initially applied followed by internal or external rotation (ER) of the foot and axial compression through the tibia. The relative motion of the talus and navicular bones was tracked using 3-dimensional optoelectric targets. Motion data were recorded in the traditional anatomical reference frame and then transformed into the TN joint frame. In the TN joint frame, relative to the intact (preoperative) state, the plate fixation group PS showed a significant reduction in separation along the long axis of the talus in 3 out of the 4 loading scenarios (P values = .007, .02, and .05). The PS construct also significantly restricted the flexion-extension motion at the joint compared with the 2S construct, during the ER tests (P values = .002 and .001). In our simulated weight-bearing model, a dorsal locked compression plate with 1 retrograde screw was more effective at limiting the 3D motion across the TN joint compared with the traditional construct of 2 retrograde screws.

Forefoot Strikers Exhibit Lower Running-Induced Knee Loading than Rearfoot Strikers

Knee pain and Achilles tendinopathies are the most common complaints among runners. The differences in the running mechanics may play an important role in the pathogenesis of lower limb overuse injuries. However, the effect of a runner's foot strike pattern on the ankle and especially on the knee loading is poorly understood. The purpose of this study was to examine whether runners using a forefoot strike pattern exhibit a different lower limb loading profile than runners who use rearfoot strike pattern. Nineteen female athletes with a natural forefoot strike (FFS) pattern and pair-matched women with rearfoot strike (RFS) pattern (n = 19) underwent 3-D running analysis at 4 m·s⁻¹. Joint angles and moments, patellofemoral contact force and stresses, and Achilles tendon forces were analyzed and compared between groups. FFS demonstrated lower patellofemoral contact force and stress compared with heel strikers (4.3 ± 1.2 vs 5.1 ± 1.1 body weight, P = 0.029, and 11.1 ± 2.9 vs 13.0 ± 2.8 MPa, P = 0.04). In addition, knee frontal plane moment was lower in the FFS compared with heel strikers (1.49 ± 0.51 vs 1.97 ± 0.66 N·m·kg⁻¹, P =0.015). At the ankle level, FFS showed higher plantarflexor moment (3.12 ± 0.40 vs 2.54 ± 0.37 N·m·kg⁻¹; P = 0.001) and Achilles tendon force (6.3 ± 0.8 vs 5.1 ± 1.3 body weight; P = 0.002) compared with RFS. To our knowledge, this is the first study that shows differences in patellofemoral loading and knee frontal plane moment between FFS and RFS. FFS exhibit both lower patellofemoral stress and knee frontal plane moment than RFS, which may reduce the risk of running-related knee injuries. On the other hand, parallel increase in ankle plantarflexor and Achilles tendon loading may increase risk for ankle and foot injuries.

EFFECTS OF STRIKING STRATEGY ON LOWER EXTREMITY LOADING DURING RUNNING

BackroundIt is expected that every second runner has a running-related overuse injury each year. The knee joint and Achilles tendon are the most commonly injured sites covering both about one...

US AND DOPPLER-GUIDED SURGICAL TREATMENT BASED ON IMMUNOHISTOCHEMICAL FINDINGS IN MIDPORTION ACHILLES TENDINOPATHY SHOWS GOOD CLINICAL RESULTS AND FAST RETURN TO ACTIVITY

IntroductionTreatment of midportion Achilles tendinopathy has been known to be difficult. Recent ultrasound(US) and Doppler(CD) findings (high blood flow outside ventral tendon), together with results of immunohistochemical analyses (marked presence...

The Effect of Foot Strike Pattern on Achilles Tendon Load During Running

In this study we compared Achilles tendon loading parameters during barefoot running among females with different foot strike patterns using open-source computer muscle modeling software to provide dynamic simulations of running. Muscle forces of the gastrocnemius and soleus were estimated from experimental data collected in a motion capture laboratory during barefoot running for 11 runners utilizing a rearfoot strike (RFS) and 8 runners utilizing a non-RFS (NRFS) pattern. Our results show that peak Achilles tendon force occurred earlier in stance phase (p = 0.007), which contributed to a 15% increase in average Achilles tendon loading rate among participants adopting a NRFS pattern (p = 0.06). Stance time, step length, and the estimated number of steps per mile were similar between groups. However, runners with a NRFS pattern experienced 11% greater Achilles tendon impulse each step (p = 0.05) and nearly significantly greater Achilles tendon impulse per mile run (p = 0.06). This difference equates to an additional 47.7 body weights for each mile run with a NRFS pattern. Runners considering a NRFS pattern may want to account for these novel stressors and adapt training programs accordingly.

Influence of calcaneus angle and muscle forces on strain distribution in the human Achilles tendon

BackgroundHeterogeneous distribution of tendon strain is considered to contribute to the development of the Achilles tendon overuse injuries. Force distribution between the three portions of the triceps surae muscle and position of the calcaneus might affect the extent of strain differences within the Achilles tendon. Purpose of this study was to determine the effect of changes in force distribution within the triceps muscle and changes in calcaneus position on intratendinous strain distribution of the Achilles tendon. MethodsFive cadaveric Achilles tendons including complete triceps surae and calcaneus were dissected. Specimens were mounted in a loading simulator allowing independent force application for the three parts of triceps muscle and changes calcaneus eversion and inversion position. Strain was determined in different aspects of the Achilles tendon. FindingsChanges of calcaneus position resulted in intratendinous strain differences up to 15%, changes in force distribution within the triceps muscle resulted in strain differences up to 2.5%. Calcaneal eversion was connected to a higher degree of strain in medial tendon portions, while inversion increased strain in lateral tendon portions. InterpretationMedio-lateral, proximo-distal and dorsal–ventral distribution of tendon strain is rather influenced by kinematics of the subtalar joint than by muscular imbalances within the triceps muscle. Clinical movement analyses should focus on motion pattern combining rearfoot eversion with high Achilles tendon load. The results indicate that twist of the Achilles tendon fascicles seems of paramount importance in balancing tendon strain. To get more insight into the Achilles tendon injuries pathogenesis future research should focus on methods monitoring heterogeneous distribution of strain in vivo.

Spatial orientation of the subtalar joint axis is different in subjects with and without Achilles tendon disorders

BackgroundThere are many possible predisposing factors for Achilles tendon disorders suggested in the literature but their pathogenetic relevance is not proven in most cases. The asymmetric mechanical load distribution within...