Optimal compliant-surface jumping: a multi-segment model of springboard standing jumps.

A multi-segment model is used to investigate optimal compliant-surface jumping strategies and is applied to springboard standing jumps. The human model has four segments representing the feet, shanks, thighs, and trunk-head-arms. A rigid bar with a rotational spring on one end and a point mass on the other end (the tip) models the springboard.

No effect of eccentric training on jumper's knee in volleyball players during the competitive season: a randomized clinical trial.

Background: The effect of surgery on patellar tendinopathy (jumper's knee) is questionable, and conservative treatment protocols have not been properly documented.

Purpose: : The aim of this study was to investigate the effect of a newly developed eccentric training program for patellar tendinopathy in volleyball players during the competitive season.

Study Design: Randomized clinical trial.

Optimal control simulations reveal mechanisms by which arm movement improves standing long jump performance.

Optimal control simulations of the standing long jump were developed to gain insight into the mechanisms of enhanced performance due to arm motion. The activations that maximize standing long jump distance of a joint torque actuated model were determined for jumps with free and restricted arm movement. The simulated jump distance was 40 cm greater when arm movement was free (2.

Neovascularisation and pain in jumper's knee: a prospective clinical and sonographic study in elite junior volleyball players.

Background: The nature of tendon neovascularisation associated with pain over time has not been studied.

Objective: To prospectively study the patellar tendons in elite junior volleyball players.

Methods: The patellar tendons in all students at the Swedish National Centre for high school volleyball were evaluated clinically and by ultrasonography (US) and Power Doppler (PD) sonography.

[Jumper's knee--a review].

Jumper's knee has been defined as painful chronic overuse injury of the extensor mechanism of the knee joint. The disease has a high incidence in jumping sports and depends on training frequency and level of performance. Its natural course is protracted, repetitive, and often bilaterally occurring.

High prevalence of jumper's knee and sonographic changes in Swedish elite junior volleyball players compared to matched controls.

Background: Jumper's knee is a common and troublesome condition among senior volleyball players, but its prevalence among elite junior players compared to matched non-sports active controls is not known.

Objective: To clinically, and by sonography, examine the patellar tendons in elite junior volleyball players (15-19 years) at the Swedish National Centre for volleyball and in matched controls.

Methods: The patellar tendons in the 57 students at the Swedish National Centre for high school volleyball and in 55 age, height, and weight matched not regularly sports active controls were evaluated clinically and by grey scale ultrasonography (US) and power Doppler (PD) sonography.

Mechanical properties of the take-off leg as a support mechanism in the long jump.

The aim of this study was to establish the functions of the support leg in the long jump take-off with a three-element mechanical model spring, damper, and actuator The take-off motions of eleven male long jumpers, with personal bests from 6.45 to 7.99 m, were videotaped at 250 Hz and ground reaction forces were simultaneously recorded at 1 kHz.

Neovascularisation in chronic painful patellar tendinosis--promising results after sclerosing neovessels outside the tendon challenge the need for surgery.

Sclerosing injections targeting neovascularisation have been demonstrated to give promising clinical results in patients with chronic painful Achilles tendinosis. In this study, fifteen elite or recreational athletes (12 men and three women) with the diagnosis patellar tendinosis/Jumper's knee in 15 patellar tendons were included. All the patients had a long duration of pain symptoms (mean = 23 months) from the patellar tendon, and ultra-sonography + colour doppler examination showed structural tendon changes with hypo-echoic areas and a neovascularisation, corresponding to the painful area.

Prevalence of jumper's knee among elite athletes from different sports: a cross-sectional study.

Background: The prevalence of jumper's knee across different sports has not been examined, and it is not known if there is a gender difference. Data from surgical case series indicate that there may be a high prevalence in sports with high speed and power demands.

Hypothesis: The aim of this study was to estimate the prevalence of jumper's knee in different sports among female and male athletes and to correlate the prevalence to the loading characteristics of the extensor mechanism in these sports.

Patellar tendinopathy in athletes: current diagnostic and therapeutic recommendations.

Formerly known as 'jumper's knee', patellar tendinopathy gives rise to considerable functional deficit and disability in recreational as well as professional athletes. It can interfere with their performance, often perseveres throughout the sporting career and may be the primary cause to end it. The diagnosis of patellar tendinopathy is primarily a clinical one but new imaging techniques, such as Doppler ultrasonography, may provide additional diagnostic value.

Patellar tendinosis as an adaptive process: a new hypothesis.

Background: Patellar tendinosis (PT), or "jumper's knee" is a common condition in athletes participating in jumping sports, and is characterised by proximal patellar tendon pain and focal tenderness to palpation. Hypoechoic lesions observed in the proximal patellar tendon associated with the tendinosis are typically described as being a result of degenerative change or "failed healing". We propose a new model for the development of the hypoechoic lesion observed in PT, in which the aetiology is an adaptive response to differential forces within the tendon.

[Evaluation of functional treatment of the acute Achilles tendon rupture according to the Thermann score scale (ten years experience)].

Introduction: The injury of Achilles tendon most frequently occurs as a result of overburdening of the tendon, particularly in sportsmen (runners and jumpers) even though they are not rare in the rest of the population. Biomechanical distrubances on the burdening tendon, or its continuous burdening, result in the degenerative changes in the form of pathological tenosynovial adhesions in and around the tendon that precedes the tendon rupture. In the recent years conservative functional treatment increasingly became the method of choice due to final results of the treatment.

Optimal jumping strategies from compliant surfaces: a simple model of springboard standing jumps.

A simple model of standing dives is used to investigate optimal jumping strategies from compliant surfaces and applied to springboard diving. The human model consists of a massless leg actuated by knee torque, and a lumped torso mass centered above the leg. The springboard is modeled as a mass-spring system.

Ultrasonography as a tool for diagnosis, guidance of local steroid injection and, together with pressure algometry, monitoring of the treatment of athletes with chronic jumper's knee and Achilles tendinitis: a randomized, double-blind, placebo-controlled study.

Background: The diagnosis of Achilles and patella tendinitis has until recently been based on clinical examination, and treatment with local steroid injection has been given blindly. This is the first randomized, double blind, placebo-controlled study of local steroid injection in athletes with chronic tendinitis, which used ultrasonography to increase diagnostic accuracy, to guide the correct placement of local steroid and, conjunctively with pressure algometry, to objectify and monitor the results of treatment.

Method: Forty-eight athletes each with severe symptomatic tendinitis of a patellar (24) or Achilles tendon (24) for more than 6 months, whose conditions were confirmed ultrasonographically, and who all failed conservative treatment (rehabilitation) were included in this double-blind, placebo-controlled study and treated with three ultrasonographically guided peritendinous injections of steroid or placebo.

Patellar Tendinosis: Acute Patellar Tendon Rupture and Jumper's Knee.

Patellar tendinopathy (jumper's knee) may affect athletes who engage in explosive lower-limb movements. An eccentric contraction of the quadriceps when landing after a jump may lead to acute patellar tendon rupture, the end-stage of patellar tendinopathy. Plain x-rays will usually confirm the diagnosis.

Recalcitrant Infrapatellar Tendinitis and Surgical Outcome in a Collegiate Basketball Player: A Case Report.

OBJECTIVE: To present the history, surgery, rehabilitation management, and eventual functional and surgical outcomes of a collegiate basketball player with recalcitrant jumper's knee. BACKGROUND: A 21-year-old, male collegiate basketball player had a 2-year history of anterior knee pain. DIFFERENTIAL DIAGNOSIS: Injuries that often mimic symptoms of infrapatellar tendinitis include infrapatellar fat pad irritation, Hoffa fat pad disease, patellofemoral joint dysfunction, mucoid degeneration of the infrapatellar tendon, and, in preadolescents and adolescents, Sinding-Larsen-Johannsson disease.

Isolated dislocation of the proximal tibiofibular joint in a long jumper.

Acute traumatic proximal tibiofibular joint dislocation is an exceedingly rare injury. This is a case report in a rare horizontal type joint variant, following a long jump injury. The diagnostic approach when this injury is suspected is described.

The incidence of injuries in elite junior figure skaters.

Background: There has been rapid growth in the technical and physiologic demands made on skaters who perform more and more difficult jumps, spins, lifts, throws, and free skating movements.

Purpose: To investigate the frequency of injuries and overuse syndromes in elite junior skaters.

Study Design: Questionnaire.

An overview of shock wave therapy in musculoskeletal disorders.

Shock waves are high-energy acoustic waves generated under water with high voltage explosion and vaporization. Shock wave in urology (lithotripsy) is primarily used to disintegrate urolithiasis, whereas shock wave in orthopedics (orthotripsy) is not used to disintegrate tissues, rather to induce neovascularization, improve blood supply and tissue regeneration. The application of shock wave therapy in certain musculoskeletal disorders has been around for approximately 15 years, and the success rate in non-union of long bone fracture, calcifying tendonitis of the shoulder, lateral epicondylitis of the elbow and proximal plantar fasciitis ranged from 65% to 91%.

Muscle co-activation around the knee in drop jumping using the co-contraction index.

The purpose of this study was to examine the co-activation of the rectus femoris (RF) and biceps femoris (BF) during drop jumping exercises using the co-contraction index (CI). Ten trained male long jumpers performed drop jumps from 20 cm (DJ20), 40 cm (DJ40) and 60 cm (DJ60) on a force platform. Surface electromyographic (EMG) activity of the RF and BF, vertical ground reaction force data and knee joint angular displacement and angular velocities were recorded and normalized as percentage of maximum isometric values.

The skeletal attachment of tendons--tendon "entheses".

Tendon entheses can be classed as fibrous or fibrocartilaginous according to the tissue present at the skeletal attachment site. The former can be "bony" or "periosteal", depending on whether the tendon is directly attached to bone or indirectly to it via the periosteum. At fibrocartilaginous entheses, the uncalcified fibrocartilage dissipates collagen fibre bending and tendon narrowing away from the tidemark; calcified fibrocartilage anchors the tendon to the bone and creates a diffusion barrier between the two.

Patellar tendinosis: a follow-up study of surgical treatment.

Background: Patellar tendinopathy (jumper's knee) is an overuse syndrome that frequently affects athletes. A retrospective study was done to analyze the results at a minimum of five years after the performance of a surgical technique in competitive athletes.

Methods: From 1985 to 1995, thirty-two patients (thirty-eight knees) affected by patellar tendinopathy were treated surgically after failure of nonoperative treatment.

Long-term prognosis for jumper's knee in male athletes. A prospective follow-up study.

Background: Little information is available on the long-term outcome of jumper's knee, a common problem among athletes.

Purpose: Our aim was to determine the 15-year prognosis of jumper's knee.

Study Design: Prospective case control.

Isokinetic dynamometry of knee flexors and extensors: comparative study among non-athletes, jumper athletes and runner athletes.

Unlabelled: Participation in intensive sports activities leads to muscular specializations that may generate alterations in involved articular forces and cause static (posture) and dynamic changes (alterations of articular stability, coordination, etc.). Prevention of injury requires specific functional muscular evaluation in all athletes and for any kind of sport.