Search results for "Tendon"
showing 10 items of 240 documents
In vivo muscle mechanics during normal locomotion is dependent on movement amplitude and contraction intensity
2001
The effects of movement amplitude and contraction intensity on triceps surae and quadriceps femoris muscle function were studied during repetitive hopping. In vivo forces from Achilles and patellar tendons were recorded with the optic fibre technique from eight volunteers. The performances were filmed (200 Hz) to determine changes in muscle-tendon unit length and velocity. When hopping with a small amplitude (23° knee flexion during the ground contact phase), the Achilles tendon was primarily loaded whereas patellar tendon forces were greater in large-amplitude hopping (56° knee flexion). In spite of the different magnitudes of stretch in the quadriceps femoris muscle, the stretching veloci…
Training-induced increase in Achilles tendon stiffness affects tendon strain pattern during running
2019
Background During the stance phase of running, the elasticity of the Achilles tendon enables the utilisation of elastic energy and allows beneficial contractile conditions for the triceps surae muscles. However, the effect of changes in tendon mechanical properties induced by chronic loading is still poorly understood. We tested the hypothesis that a training-induced increase in Achilles tendon stiffness would result in reduced tendon strain during the stance phase of running, which would reduce fascicle strains in the triceps surae muscles, particularly in the mono-articular soleus. Methods Eleven subjects were assigned to a training group performing isometric single-leg plantarflexion co…
Kinematics of the patellofemoral joint. Investigations on a computer model with reference to patellar fractures.
1990
Patellofemoral kinematics were studied on a computer model. The articulating point of the patella moves from distal to proximal during flexion, until the quadriceps tendon starts to turn around the femur tendo-femoral gliding. The pattern of patellofemoral movement consists of a gliding and rolling component, the latter at its maximum at the beginning of flexion. The pathway of the instant centers of motion moves from dorsal to ventral during flexion. Stress analysis shows that the contact area is at all times the area of maximum bending stress. The distal part of the patella is the part with mechanical stress at all angles of flexion. The conclusions to be drawn for treatment are that frac…
Healing of the patellar tendon donor defect created after central-third patellar tendon autograft harvest
1999
Patellar tendon donor defect (PTDD) healing after patellar tendon autograft (PTA), was evaluated in 12 lambs (24 knees), by means of conventional histology, immunohistochemistry and image analysis. The results of this study indicate that the PTDD is replaced by a tissue that does not assume the histological characteristics of a normal patellar tendon. Both the Hoffa fat pad (HFP) and the paratenon play an important role in the healing process, although qualitative and quantitative chronological differences were found, which supports the concept of a “two-time process”. The HFP initiates the repair process, and is the main active proliferative tissue compartment during the first week. Once t…
Simultaneous chronic rupture of quadriceps tendon and contra-lateral patellar tendon in a patient affected by tertiary hyperparatiroidism
2007
Abstract Spontaneous ruptures of the extensor mechanism of the knee are very rare. They tend to increase considerably in patients with metabolic diseases such as chronic renal failure, hyperparathyroidism, diabetes, gout, and systemic lupus erythematosus. The reported case regards a 48-year-old man with chronic, spontaneous and simultaneous quadriceps, and contra-lateral patellar tendon rupture. The patient suffered from chronic renal failure and for the past year from tertiary hyperparathyroidism. Ruptured tendons were repaired and both knee were evaluated monthly for the next 12 months. Good functional recovery was achieved on both knees without relapse. This case emphasizes the importanc…
Biomechanical Bases for Anterior Knee Pain and Patellar Instability
2012
The anterior knee pain syndrome and functional patellar instability in the active young person is one of the most complex knee disorders, with a multiple factor and highly variable pathogenesis, with intermingling mechanical and neurological factors. Probably the neural factor is the cause of the well established symptoms in patients with certain mechanical anomalies and a knee overuse.
Posterior Tibial Tendon Dislocation: A Case Report
2022
Abstract Isolated posterior tibial tendon dislocation is a rare condition. Diagnosis can be challenging, especially in the acute clinical setting. Predisposing factors include shallow posterior tibial tendon groove and tear of the flexor retinaculum. We report the case of traumatic subluxation of the posterior tibial tendon, illustrating imaging findings and surgical technique. Posterior tibial tendon dislocation was detected using dynamic ultrasound, while magnetic resonance was essential for a comprehensive evaluation that included underlying predisposing anatomic abnormalities and associated pathologic conditions. Conservative treatment is often unsuccessful thus surgical approach was ne…
Effects of muscle activation on shear between human soleus and gastrocnemius muscles
2017
Lateral connections between muscles provide pathways for myofascial force transmission. To elucidate whether these pathways have functional roles in vivo, we examined whether activation could alter the shear between the soleus (SOL) and lateral gastrocnemius (LG) muscles. We hypothesized that selective activation of LG would decrease the stretch-induced shear between LG and SOL. Eleven volunteers underwent a series of knee joint manipulations where plantar flexion force, LG, and SOL muscle fascicle lengths and relative displacement of aponeuroses between the muscles were obtained. Data during a passive full range of motion were recorded, followed by 20° knee extension stretches in both pass…
Estudio de la eficacia de la plicatura del tendón cantal lateral con anclaje en Y en el síndrome del ojo seco evaporativo
2018
INTRODUCCIÓN El síndrome de ojo seco (SOS) es una patología muy prevalente que afecta a la calidad de vida de los pacientes. El manejo terapéutico del SOS es complejo y varía en función del subtipo de SOS que se esté tratando. No se ha demostrado hasta el momento ninguna técnica quirúrgica que cure aquellos SOS por malposición palpebral de causa intrínseca. HIPÓTESIS, MATERIAL Y MÉTODOS La hipótesis del estudio es que la plicatura del tendón cantal lateral con anclaje en Y es eficaz en el tratamiento del SOS evaporativo de causa intrínseca. Se ha realizado un estudio prospectivo de casos y controles en el que se han reclutado en el periodo de tiempo existente entre noviembre de 2016 y novie…
In vivo triceps surae and quadriceps femoris muscle function in a squat jump and counter movement jump
2000
An optic fibre method was used to measure in humans in vivo Achilles (ATF) and patellar tendon forces (PTF) during submaximal squat jumps (SJ) and counter movement jumps (CMJ). Normal two-legged jumps on a force plate and one-legged jumps on a sledge apparatus were made by four volunteers. Kinetics, kinematics, and muscle activity from seven muscles were recorded. The loading patterns of the tendomuscular system differed among the jumping conditions, but were similar when the jumping height was varied. Peak PTF were greater than ATF in each condition. In contrast to earlier simulation studies it was observed that tendomuscular force could continue to increase during the shortening of muscle…