Osteochondritis dissecans development after bone contusion of the knee in the skeletally immature: a case series.

Osteochondritis dissecans (OCD) is thought to be an acquired osteochondral disorder, and its aetiology may be multifactorial. Trauma, both acute and repetitive events, has previously been proposed as a potential cause for OCD development. We present two cases of skeletally immature boys who developed a symptomatic OCD lesion following a femoral condyle bone contusion. These cases suggest that an acute traumatic event may lead to the development of OCD of the knee.

Volumetric injury of the physis during single-bundle anterior cruciate ligament reconstruction in children: a 3-dimensional study using magnetic resonance imaging.

PURPOSE: To determine the volume of injury to the physis during anterior cruciate ligament (ACL) reconstruction in pediatric patients. METHODS: Magnetic resonance imaging scans of 10 pediatric knees were converted into 3-dimensional models. Computer-aided design/computer-aided manufacturing software placed drill holes (6, 7, 8, and 9 mm in diameter) in these models, simulating tunnels used for ACL reconstruction. The software was used to calculate total physeal volume and volume of physis removed by the tunnel. The ratio of physeal volume removed to the total physeal volume was determined. RESULTS: For 6-, 7-, 8-, and 9-mm-diameter drill holes, the mean percent of physeal volume removed/total physeal volume was 1.6%, 2.2%, 2.9%, and 3.8%, respectively, for the tibia and 2.4%, 3.2%, 4.2%, and 5.4%, respectively, for the femur. For all subjects, the volume removed was less than 7.0% for the tibia and 9.0% for the femur by use of drill holes from 6 to 9 mm. The tibial drill hole was centrally placed in all cases compared with a more peripheral drill hole placement of the femur. CONCLUSIONS: Drill hole placement during ACL reconstruction produces a zone of physeal injury. The overall volume of injury is relatively low, which reduces the risk of physeal arrest. With careful drill hole placement, the region of injury is central on the tibia, and the total volume of injury can be less than 5.0% of the physeal volume. For the femur, the total volume can be less than 5.0% as well. However, the region of injury is peripheral, which carries a higher risk of physeal arrest. CLINICAL RELEVANCE: A better understanding of the relation between the ACL and physis may guide the placement of drill holes, which have a lower risk of producing physeal arrest.

Influence of towing force magnitude on the kinematics of supramaximal sprinting.

The purpose of this study was to determine the influence of towing force magnitude on the kinematics of supramaximal sprinting. Ten high school and college-age track and field athletes (6 men, 4 women) ran 60-m maximal sprints under 5 different conditions: Nontowed, Tow A (2.0% body weight [BW]), Tow B (2.8% BW), Tow C (3.8% BW), and Tow D (4.7% BW). Three-dimensional kinematics of a 4-segment model of the right side of the body were collected starting at the 35-m point of the trial using high-speed (250 Hz) optical cameras. Significant differences (p < 0.05) were observed in stride length and horizontal velocity of the center of mass during Tow C and Tow D. For Tow D, a significant increase (p = 0.046) in the distance from the center of mass to the foot at touchdown was also observed. Contact time decreased significantly in all towing conditions (p < 0.01), whereas stride rate increased only slightly (<2.0%) under towed conditions. There were no significant changes in joint or segment angles at touchdown, with the exception of a significant decrease (p = 0.044) in the flexion/extension angle at the hip during the Tow D condition. We conclude that towing force magnitude does influence the kinematics of supramaximal running and that potentially negative training effects may arise from towing individuals with a force in excess of 3.8% BW. Therefore, we suggest that coaches and practitioners adjust towing force magnitude for each individual and avoid using towing forces in excess of 3.8% of the athlete's BW.

Does cardiac morphology predict plasma brain natriuretic Peptide levels in adolescent athletes?

OBJECTIVE: The purpose of this study was to establish the relationship of plasma levels of brain natriuretic peptide (BNP) to physiologic parameters and cardiac morphologic characteristics in a population of young athletes. Our hypothesis is that physiologic and cardiac morphologic characteristics do not predict BNP levels in adolescent athletes. DESIGN: Observational study. SETTING: Outpatient hospital. PARTICIPANTS: Thirty healthy male adolescent high school football players (16.0 +/- 1.1 years). INTERVENTIONS: Physical exam, electrocardiography, plasma BNP measurement by rapid fluorescent immunoassay, and limited echocardiography. MAIN OUTCOME MEASURES: Null hypothesis-physiologic parameters and cardiac morphology do not predict plasma BNP levels in healthy adolescent football players. Significance level set at P < 0.05. RESULTS: Plasma BNP for this population was 11.9 +/- 10.2 pg/mL. There was no correlation between BNP and mean arterial pressure (r = -0.09, P = 0.64), body mass index (r = 0.11, P = 0.57), interventricular septal thickness (r = -0.15, P = 0.44), left ventricular (LV) wall thickness (r = 0.00, P = 0.99), relative wall thickness (r = -0.04, P = 0.84), LV mass (r = 0.05, P = 0.79), or LV mass index (r = 0.11, P = 0.55). CONCLUSIONS: Plasma BNP levels in healthy adolescent athletes have no correlation to body mass index or LV mass, even when corrected for body surface area.

The anatomy of the proximal tibia in pediatric and adolescent patients: implications for ACL reconstruction and prevention of physeal arrest.

Although the treatment of anterior cruciate ligament (ACL) tears in skeletally immature patients is still controversial, several studies have advocated ACL reconstruction in selected patients to prevent secondary injury. The proximal tibial physis is a structure at risk during ACL reconstruction in young patients, and physeal growth complications have been reported after surgery in this area. The relationship between the ACL and the proximal tibial physeal/apophyseal regions is poorly understood. This study examined the MRI anatomy of the ACL and the proximal tibia apophysis and epiphysis. MRIs of 59 skeletally immature knees were reviewed (Average age = 12.75 years, range 6-15) to define the anatomy of the epiphyseal and apophyseal regions. Measurements were recorded in three parasagittal planes: (1) at the lateral border of the patellar tendon, (2) the lateral edge of the ACL insertion, and (3) the medial edge of the ACL insertion. A single three-dimensional (3D) computed tomography (CT) scan was used to evaluate the position of standard drill holes used in ACL reconstruction to assess for potential degree of injury to the epiphyseal and apophyseal growth plates. In the parasagittal planes, the average height of the epiphysis was 19.6, 20.7, and 21.5 mm at the lateral border of the patellar tendon, the lateral border of the ACL, and the medial border of the ACL, respectively. At the level of the same landmarks, the apophysis extended below the physis at an average of 20.2, 16.8, and 7.0 mm, respectively. Expressed as a percentage of epiphysis height this was an average of 104, 82, and 33%, respectively. Examination of 3D CT images revealed that variations in drill hole placement had effects on the volume of injury to the proximal tibial physis and apophysis. Drill holes that started more medial, distal, and with a steeper angle of inclination reduced the amount of physis and apophysis violated when compared with holes placed more lateral, proximal, and with a shallow angle of inclination. The proximal tibial physis and apophysis is vulnerable to injury by drill hole placement during ACL reconstruction in skeletally immature patients. This paper defines the anatomic relationship of the apophyseal and epiphyseal regions of the physis in the proximal tibia. The volume of injury to the physis can be reduced by avoiding tunnel placement that is too lateral or too proximal on the tibia. A better understanding of these relationships may guide the placement of tibial drill holes, which have a lower risk of producing significant physeal damage.

Lack of effect of a knee ligament injury prevention program on the incidence of noncontact anterior cruciate ligament injury.

BACKGROUND: Studies have suggested that exercise programs can reduce the incidence of noncontact injuries of the anterior cruciate ligament in female athletes. We conducted a two-year prospective study to assess the effects of a knee ligament injury prevention exercise program on the incidence of noncontact anterior cruciate ligament injuries in high-school female athletes. METHODS: A prospective cohort design was used to study high-school female athletes (playing soccer, basketball, and volleyball) from fifteen schools (112 teams) for two consecutive seasons. The schools were divided into treatment and control groups. The treatment group participated in a plyometric-based exercise program twice a week throughout the season. Practice and game exposures and compliance with the exercise program were recorded on a weekly basis. Suspected noncontact anterior cruciate ligament injuries were confirmed on the basis of the history as well as at the time of surgery and/or with magnetic resonance imaging. RESULTS: A total of 1439 athletes (862 in the control group and 577 in the treatment group) were monitored. There were six confirmed noncontact anterior cruciate ligament injuries: three in the treatment group, and three in the control group. The incidence of noncontact anterior cruciate ligament injuries per 1000 exposures was 0.167 in the treatment group and 0.078 in the control group, yielding an odds ratio of 2.05, which was not significant (p > 0.05). CONCLUSIONS: Our results suggest that a twenty-minute plyometric-based exercise program that focuses on the mechanics of landing from a jump and deceleration when running performed twice a week throughout the season will not reduce the rate of noncontact anterior cruciate ligament injuries in high-school female athletes.

The effects of a commercially available warm-up program on landing mechanics in female youth soccer players.

The purpose of this study was to examine lower extremity kinematics following implementation of the Sportsmetrics Warm-Up for Injury Prevention and Performance (WIPP) training program. The hypothesis was that there would be no difference in landing mechanics between 2 groups of female youth soccer players (9-11 years of age), with 1 group (Treatment) completing the 8-week-duration (2 days per week) WIPP program and the other serving as a Control group. We recruited 21 female youth soccer players. Treatment (n = 12) and Control (n = 9) groups were established. Using the Sportsmetrics Software for Analysis of Jumping Mechanics, we analyzed lower extremity movement during landing after subjects jumped off a 30.5-cm box and immediately went into a vertical jump. No significant changes in knee separation values were observed in the Treatment group after 8 weeks of WIPP training. The results indicate that 8 weeks of WIPP training did not significantly alter landing strategies.

Effects of a knee ligament injury prevention exercise program on impact forces in women.

Previous research suggests high impact forces generated during landings contribute to noncontact anterior cruciate ligament (ACL) injuries. In women, neuromuscular differences appear to modify the ability to dissipate landing forces when compared to men. This study examined peak vertical impact forces (F(p)) and rate of force development (RFD) following a 9-week, low-intensity (simple jump-landing-jump tasks) and volume (number of foot contacts per workout) plyometric-based knee ligament injury prevention (KLIP) program. Female subjects were randomly assigned into control (n = 14) and treatment (n = 14) groups. Treatment subjects attended KLIP sessions twice a week for 9 weeks, and control subjects received no intervention. Ground reaction forces (F(p) and RFD) generated during a step-land protocol were assessed at study onset and termination. Significant reductions in F(p) (p = 0.0004) and RFD (p = 0.0205) were observed in the treatment group. Our results indicate that 9 weeks of KLIP training altered landing strategies in women to lower F(p) and RFD. These changes are considered conducive to a reduced risk of knee injury while landing.

Kinematic MRI assessment of McConnell taping before and after exercise.

BACKGROUND: The authors assessed the effectiveness of McConnell medial glide taping after exercise using an MRI extremity scanner. HYPOTHESIS: McConnell taping would not be effective in maintaining medial glide of the patella after exercise. METHODS: Eighteen healthy women (mean age 22.28 +/- 2.02 years) participated in the study. The patellofemoral joint was imaged at 4 knee flexion angles (0 degrees, 12 degrees, 24 degrees, and 36 degrees ) in 3 conditions (no tape, with McConnell taping-medial glide, and with tape after exercise). Effectiveness was determined by measuring lateral patellar displacement. ANOVA and post hoc paired t tests were used to test for changes in lateral patellar displacement at each knee angle and condition. RESULTS: Statistical analysis revealed significant differences in lateral patellar displacement at all test angles, between the tape and no tape and between tape and tape after exercise conditions. CONCLUSIONS: McConnell medial glide taping resulted in significant medial glide of the patellofemoral joint at all 4 knee angles before but not after exercise. However, McConnell medial glide taping may be effective under controlled rehabilitation conditions in which exercise is less intense. CLINICAL RELEVANCE: Beneficial effects of McConnell medial glide taping may be related to factors other than altered patellar alignment.

Anterior cruciate ligament injury in paediatric and adolescent patients: a review of basic science and clinical research.

Anterior cruciate ligament (ACL) injuries are recognised with greater frequency in children and adolescents. Non-operative treatment of ACL injuries in children may lead to knee instability and secondary injuries, especially in those who return to sports. ACL reconstruction is controversial in skeletally immature patients because of potential damage to the proximal tibial and distal femoral physes, which may lead to premature arrest and/or leg length discrepancies. This paper reviews studies of ACL injuries in children and adolescents, and examines basic science and clinical studies concerning physeal arrest secondary to ACL reconstruction tunnels. Some animal studies support the conclusion that ACL reconstructions in children have the potential to cause growth disturbances, and there are reports of growth plate complications due to ACL reconstruction in skeletally immature patients. There is evidence that ACL reconstruction can be performed in select skeletally immature patients, but the risk of growth plate complications must be considered.

Mountain biking injuries: an update.

This article reviews the available literature regarding injuries in off-road bicyclists. Recent progress in injury research has allowed the description of several patterns of injury in this sport. Mountain biking remains popular, particularly among young males, although sales and participation figures have decreased in the last several years. Competition in downhill racing has increased, while cross-country racing has decreased somewhat in popularity. Recreational riders comprise the largest segment of participants, but little is known about the demographics and injury epidemiology of noncompetitive mountain cyclists. Most mountain bikers participating in surveys reported a history of previous injuries, but prospective studies conducted at mountain bike races have found injury rates of <1%. The most common mechanism of injury involves a forward fall over the handlebars, usually while riding downhill, which can result in direct trauma to the head, torso and upper extremities. A variety of factors can be associated with this type of fall, including trail surface irregularities, mechanical failures and loss of control. In mountain bike racing the risk of injury may be higher for women than men. Minor injuries such as abrasions and contusions occur frequently, but are usually of little consequence. Fractures usually involve the torso or upper extremities, and shoulder injuries are common. Head and face injuries are not always prevented by current helmet designs. Fatal injuries are rare but have been reported. Improvements in safety equipment, rider training and racecourse design are suggested injury prevention measures. The authors encourage continued research in this sport.

Gender differences in acute mountain bike racing injuries.

OBJECTIVE: To evaluate injury rates and patterns in off-road bicycle racing, and to compare the findings in male and female cyclists. SETTING: The study was conducted from 1994-2001 at a large off-road bicycling competition held for 4 days each summer at Mammoth Mountain, California. DESIGN: Injured cyclists were evaluated at the first aid station or at the local hospital. Registration data were used to estimate the number of male and female competitors in each race. PARTICIPANTS: Cyclists who sustained an injury during a race and were unable to finish the race due to the injury were included in the study. 22 female subjects and 71 male subjects met the inclusion criteria during the 8-year study period. There were a total of 20,769 race participants during the study period. MAIN OUTCOME MEASURES: Injuries were categorized, and injury rates were calculated. RESULTS: The overall injury rate during the study period was 0.77% (22/2,869) for women versus 0.40% (71/17,900) for men (p = 0.01). Fractures were sustained by 45.5% (10/22) of female subjects versus 21.1% (15/71) of male subjects (p = 0.03). Odds ratios indicate that overall, women were 1.94 times more likely than men to sustain an injury and 4.17 times more likely to sustain a fracture. CONCLUSIONS: These data suggest that although participation in this sport is higher among men, the risk of injury is greater for women.

The tibial attachment of the anterior cruciate ligament in children and adolescents: analysis of magnetic resonance imaging.

Recent studies have demonstrated that skeletally immature athletes with an ACL injury may require surgical reconstruction if they return to high-demand sports. This study used MRI to compare the anatomy of the ACL in skeletally immature and adult subjects. Measurements were recorded in the sagittal plane for the anterior-posterior dimension of the proximal tibia, and the anterior, center, and posterior limits of the ACL, and the roof inclination angle of the femur. These values were compared to established reference values for adult knee anatomy. In skeletally immature women ( n=7) the ACL anterior limit, center and posterior limit, and roof inclination angle were 28%, 46%, 63%, and 38 degrees, respectively, compared to 28%, 44%, 60%, and 35 degrees in adult women. In skeletally immature men ( n=15) the ACL anterior limit, center, posterior limit, and roof inclination angle were 27%, 43%, 59%, and 40 degrees, respectively, compared to 28%, 44%, 59%, and 37 degrees in adult men. In the younger subjects the overall dimensions of the proximal tibia were smaller than that in adults, but the anatomical landmarks for the ACL were proportional. If ACL reconstruction is performed in skeletally immature subjects, the smaller dimensions of the tibia need to be considered, and the use of anatomical landmarks is an important factor in graft placement

Case Report: Spontaneous Pneumothorax in a Jogger.

Athletes with a high pain tolerance may delay medical treatment for idiopathic spontaneous pneumothorax, even when significant symptoms are present.