David H. Janda

Innervation of the human knee joint by substance-P fibers

Anterior knee pain is a frequent musculoskeletal complaint affecting all ages, both sexes, athletes, and nonathletes alike. Numerous theories have been proposed regarding its etiology including patellar malalignment, quadriceps insufficiency, subluxation, quadriceps muscle tightness, and chondral defects. However, the mechanism by which these factors produce this pain is not clear. Knowledge of the distribution of nociceptive nerve fibers around the knee would seem to provide insight in treating these painful conditions. Eleven human patellae--eight specimens from patients with degenerative patellofemoral disease and three normals--were evaluated. Immunohistochemical techniques using monoclonal antibody to substance-P were employed to identify nociceptive fibers. Substance-P is a nociceptive neurotransmitter found in afferent nerve fibers. Substance-P fibers were isolated in the retinaculum, fat pad, periosteum, and subchondral plate of patellae affected with degenerative disease. This study demonstrates that selective tracting of nociceptive pain fibers is possible around the knee both in soft tissue and, in some circumstances, bone. The subchondral plate of normal patellae did not demonstrate erosion channels, but those with chondral defects from degenerative disease did. Nociceptive fibers found in these defects may explain the origin of symptoms in some patients. The distribution of substance-P nerve fibers in the soft tissues around the knee suggests that denervation may be the mechanism by which surgical procedures for anterior knee pain produce favorable results.

Translation of the glenoihumeral joint with the patient under anesthesia

This study was undertaken to determine glenohumeral translation in the anesthetized patient. Radiographically assessed humeral translation was measured in 18 members of a control group, 10 patients with anterior instability, and 10 patients with multidirectional instability. In the control group stress radiographs revealed anterior translation of 17% (percentage of the diameter of the glenoid from anterior to posterior), posterior of 26%, and inferior to 29% (percentage of diameter of glenoid from superior to inferior). In patients with anterior instability anterior translation was 29%, posterior translation was 21%, and inferior translation was 49%. In patients with multidirectional instability anterior translation was 28%, posterior translation was 52%, and inferior translation was 46%. Overlap in translation was seen between normal members and those with instability. The most practical method to grade anterior and posterior translation of the humeral head within the glenoid fossa involves a clinical assessment of where the center of the humeral head rests in reference to the glenoid rim.

Posterior Instability of the Glenohumeral Joint A Technique of Repair

Seventeen patients underwent posterior capsulotendi nous tensioning procedures to eliminate recurrent pos terior glenohumeral instability. Fourteen patients were evaluated an average of 44 months (range, 18 to 98) after surgery. The average patient age was 27 years. Before surgery, all patients were unable to perform their activities of daily living, occupational activities, and athletic activities. Preoperatively, the average pain rating score on a visual analog scale was 5 of 10 at rest and 9 of 10 with activities. Six patients had previous anterior reconstructions. After surgery, the average range of motion was 174° of forward elevation and 69° of external rotation; internal rotation was to the thumb level of T-8. No patient had a recurrence of posterior instability. After surgery, the average pain rating score was 2 of 10 at rest and 4 of 10 with activities. All patients improved after their operations, but four pa tients were minimally disabled from activities of daily living; six patients experienced shoulder fatigue at work; and four patients had difficulty with sports activ ities. Overall, 13 of the 14 patients were satisfied with their surgical procedures and their outcomes.

An evaluation of the cumulative concussive effect of soccer heading in the youth population

Soccer is the most popular team sport in the world, with 120 million individuals participating and 16 million of these individuals being based in the United States. In addition, soccer has become the fastest growing team sport in the United States over the past 10 years. Head impact injuries have been cited as comprising 15% of all injuries related to soccer. Previous studies have identified the technique of heading as being a significant factor in head impact injuries. In fact, 85% of various subgroups of participants, 19 years of age and older, have had a diminution in cognitive function abilities on a permanent basis. It was the purpose of this study to evaluate the effect of repetitive head impacts due to heading in 57 youth soccer players with a mean age of 11.5 years. The data were collected over three seasons during the first year, which correlated to approximately 60 games and/or practices. One team of 18 boys was followed for an additional year. The data collected included a cognitive function test, as well as documentation of concussive symptoms. These cognitive evaluations, conducted at both periods of time, revealed that statistically significant differences were not evident when compared to standardized norms with the exception of verbal learning. There was an inverse relationship between the number of ball impacts and verbal learning. Of note, however, is that 49% of the year-one study group did complain of headaches after heading the ball.

A three-phase analysis of the prevention of recreational softball injuries

Recreational sports injuries are expensive to society. Prevention of such injuries must be a major public health goal. In a previous retrospective study, base sliding was found to be responsible for 71 % of recreational softball injuries. Because most injuries occurred during rapid deceleration against stationary bases, quick-release (break-away) bases were evaluated as a means to modify this mechanism of injury. In a prospective study, 633 softball games were played on break-away base fields and 627 games were played on stationary base fields. Forty-five sliding injuries occurred on the station ary base diamonds (1 injury for every 13.9 games) and only two sliding injuries occurred on the break-away fields (1 injury for every 316.5 games). The medical costs for injuries on the stationary base fields was 79 times greater than that on the break-away fields. In a 1035 game follow-up study performed on all fields equipped with break-away bases, two sliding injuries occurred (1 injury for every 517.5 games). Installing break-away bases in fields used by recrea tional leagues would achieve a significant reduction of serious softball injuries (98%) and, therefore, should be mandatory. Based on our findings, the Centers for Disease Con trol has estimated 1.7 million injuries would be pre vented nationally per year, saving

An analysis and comparison of soccer shin guards.

2.0 billion per year nationally in acute medical care costs.

Prevention of commotio cordis in baseball: an evaluation of chest protectors

Worldwide >40 million amateurs participate in the team sport of soccer. With 647,368 injuries occurring from 1989 through 1992, the risk of injury during the play of soccer is evident. Lower extremity injuries have been found to comprise 13.1% of the total injuries in soccer. To date, a comprehensive evaluation of protective equipment utilized to prevent lower extremity injuries in soccer has been lacking. This study utilized a 5th percentile Hybrid III female dummy to evaluate the effectiveness of shin guards in attenuating the forces which can lead to lower extremity injuries. A pendulum impact apparatus simulated one player being kicked by another. Impacts were delivered to the anterior tibial region of the Hybrid III dummy and peak loads were recorded. Load forces were reduced 41.2–77.1% with the utilization of shin guards. Even at extreme temperatures, the guards were found to be effective in lowering the amount of impact force transferred to the shin region. The results of this study indicate that the use of shin guards will attenuate the force of impact to the tibia and thus reduce the risk of injury.

Blunt chest impacts: assessing the relative risk of fatal cardiac injury from various baseballs

BACKGROUND In a recent study of fatal chest impacts by baseballs, 28% of the children were wearing a chest protector. This study evaluates the effectiveness of chest protectors in reducing the risk of commotio cordis. METHODS Five commercially available chest protectors were placed on a three-rib structure simulating the chest and impacted at 40, 50, 60, and 70 miles per hour by a standard baseball. Ten repeated tests were conducted on each vest in random order, and on the control (unprotected chest). The viscous response (or viscous criterion [VC]) was used to assess differences in fatality risk. RESULTS One vest had a statistically lower VC (average, 50.6%, p < 0.05) for all impact speeds. Three averaged 18.7% to 27.7% lower VC, but were significantly different only at higher speeds. One vest had an average 34.2% higher VC, and was significantly higher at 40 to 50 miles per hour (p < 0.05). A method was proposed linking laboratory test results to real-world incidents of ventricular fibrillation. CONCLUSIONS The majority of commercially available chest protectors fail to provide consistent reductions in commotio cordis risk. Nonetheless, there are benefits from their use in baseball until improved safety equipment is developed and standard tests are established to assess sport equipment effectiveness.

Goal Post Injuries in Soccer A Laboratory and Field Testing Analysis of a Preventive I ntervention

OBJECTIVE To compare various soft-core baseballs for their ability to reduce the risk of fatal chest-impact injury. DESIGN This study used a three-rib biomechanical surrogate to quantitatively analyze chest impacts from nine soft-core baseballs and one standard baseball, which served as the control. Impacts were achieved with an air cannon system, with the velocity of impact being 40, 50, and 60 mph. MATERIALS AND METHODS The deflection of the three-rib structure at the sternum was measured and used to calculate the viscous criterion, which correlates with risk of chest-impact injury. MEASUREMENTS AND MAIN RESULTS Analysis showed that baseballs with lighter mass had a significantly lower viscous criterion (p < 0.05). Those with a similar mass had no change in the viscous criterion, and the heaviest soft-core baseball had a significantly higher viscous criterion at an impact velocity of 60 mph. CONCLUSION The results of this study indicate that soft-core baseballs may not differ from a standard baseball with regard to the risk of fatal chest-impact injury while playing baseball. Other techniques, such as preventive coaching, need to be implemented when trying to improve baseball safety.

An Analysis of Preventive Methods for Baseball-Induced, Chest Impact Injuries

Soccer is the most popular team sport worldwide, with approximately 40 million amateur participants. Most fa talities in soccer are related to player impact with the goal post. This study focuses on two case reports, a laboratory testing phase, and a pilot field testing phase of preventive equipment that can be used around the goal to prevent injury. Horizontal and vertical impact testing in the laboratory revealed impact force was di minished when the goal post was covered with protec tive padding (reduction of 31% and 63%) (P < 0.05). These data showed a statistically significant decrease in force at all temperatures. In the pilot field testing phase of the study, 471 games were monitored. Soccer teams participating in youth, teen, and adult soccer leagues were included in this phase of the study. During the 3-year study, there were seven player collisions with padded goal posts, and no injuries were recorded. The use of padded goal posts within the game of soccer has been documented to reduce the possibility of injury, both in the laboratory phase and in the pilot field testing phase.