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William H. Clark and Jason R. Franz

The triceps surae muscle–tendon units are important in governing walking performance, acting to regulate mechanical behavior of the ankle joint through the interaction between active muscle and passive elastic structures. 1 – 3 Ankle joint quasi-stiffness (k A ), the slope of the relation between

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Dai Sugimoto, Benton E. Heyworth, Jeff J. Brodeur, Dennis E. Kramer, Mininder S. Kocher and Lyle J. Micheli

bone patellar tendon bone (BTB) and hamstring tendon (HT) grafts, especially skeletally mature patients with ACL. For skeletally immature ACL patients with significant growth remaining, physeal-sparing techniques are often utilized. The most well-studied physeal-sparing technique to date is the

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Aaron Turner

The present case describes the conservative treatment of a supraspinatus tendon tear with accompanying scapular dyskinesis in a synchronized ice skater. While rotator cuff injuries are present in ice skating, 20 , 21 to the author’s knowledge, this is the first case study detailing a successful

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Jay R. Ebert, Kate E. Webster, Peter K. Edwards, Brendan K. Joss, Peter D’Alessandro, Greg Janes and Peter Annear

return to sport (RTS). 4 , 5 Traditionally, a bone–patellar tendon–bone (BPTB) graft has been the preferred method of ACLR, 6 though systematic reviews over the past 10–15 years have demonstrated the lack of superiority of BPTB over hamstring autografts, 7 with less postoperative complications

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Ian J. Dempsey, Grant E. Norte, Matthew Hall, John Goetschius, Lindsay V. Slater, Jourdan M. Cancienne, Brian C. Werner, David R. Diduch and Joseph M. Hart

discharge from PT (yes and no), graft type (bone-patellar tendon-bone [BPTB] and hamstring tendon [HT]), meniscectomy status (yes and no), and meniscus repair status (yes and no). Dependent variables included PT questionnaire item response, IKDC subjective knee form, knee extensor maximum voluntary

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Genki Hatano, Shigeyuki Suzuki, Shingo Matsuo, Satoshi Kataura, Kazuaki Yokoi, Taizan Fukaya, Mitsuhiro Fujiwara, Yuji Asai and Masahiro Iwata

technique commonly used to acutely increase ROM. 11 – 14 The proposed mechanisms for this include an increased stretch tolerance due to altered sensation 12 , 14 , 15 and a change in the stiffness/viscoelastic properties of the muscle–tendon unit, 12 – 14 , 16 – 18 which result in improved movement and

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Pier Paolo Mariani, Luca Laudani, Jacopo E. Rocchi, Arrigo Giombini and Andrea Macaluso

autologous bone-patellar tendon-bone graft, and (6) physical therapy carried out at same center with the same protocol for 3 months. Another reason to limit our investigation to the early postoperative period was because it is difficult to have a homogenous cohort of patients who follow the same protocol of

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Bareket Falk

Children develop lower levels of muscle force, and at slower rates, than adults. Although strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency while minimizing the risk of strain- related tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (age 8.9 ± 0.3 yr) were equally divided into control (nontraining) and experimental (training) groups. The training group completed a l0-week RT intervention consisting of 2–3 sets of 8–15 plantar flexion contractions performed twice weekly on a recumbent calf-raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness, and Young’s modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve), and rate of electromyographic (EMG) increase (REI; slope of the EMG time curve) were measured before and after RT. Tendon stiffness and Young’s modulus increased significantly after RT in the experimental group only (~29% and ~25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively; not significant) which may have implications for tendon injury risk and muscle fiber mechanics. A decrease of ~13% in EMD was found after RT for the experimental group, which paralleled the increase in tendon stiffness (r = −0.59); however, RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD. These findings are of importance within the context of the efficiency and execution of movement.

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Thomas D. O’Brien

Children develop lower levels of muscle force, and at slower rates, than adults. While strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency while minimizing the risk of strainrelated tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (8.9 ± 0.3 years) were equally divided into control (nontraining) and experimental (training) groups. The training group completed a 10-week RT intervention consisting of 2-3 sets of 8-15 plantar flexion contractions performed twice weekly on a recumbent calf raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness and Young’s modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve) and rate of EMG increase (REI; slope of the EMG-time curve) were measured before and after RT. Tendon stiffness and Young’s modulus increased significantly after RT in the experimental group only (~29% and ~25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively, n.s) which may have implications for tendon injury risk and muscle fiber mechanics. A ~13% decrease in EMD was found after RT for the experimental group which paralleled the increase in tendon stiffness (r = −0.59), however RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD. These findings are of potential importance within the context of the efficiency and execution of movement.

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Özlem Feyzioğlu, Özgul Öztürk, Bilsen Sirmen and Selim Muğrabi

return to preinjury performance and functional level of professional athletes or injured individuals. 8 ACLR can be performed using a hamstring or patellar tendon autograft. In surgical techniques using hamstring tendon grafts, anterior knee pain, loss of proprioception, decrease of hamstring muscle