Excessive distraction stress at the throwing shoulder is similar to that found in baseball pitchers, which suggests that windmill softball pitchers are at risk for overuse injuries. Normative information regarding upper extremity kinematics and kinetics for elite softball pitchers has been established.

The change in shock absorption properties of running shoes was evaluated as a function of miles run. Different models of running shoes encompassing a wide range in retail price were obtained and mechanically tested to simulate the repeated heel strikes of running. The energy absorbed by the shoes was determined from the area under the load deformation curve at the equivalent of 0, 5, 10, 25, 50, 75, 100, 125, 150, 200, 250, 300, and 500 miles of running. Shoes were also tested at similar intervals after having been worn by volunteers during normal training. An approximate 33% difference in the initial shock absorption was observed in the different shoe models. In general, the shoes retained approximately 75% of their initial shock absorption capability after 50 miles of simulated running, and approximately 67% after 100 to 150 miles. Between 250 and 500 miles the shoes retained less than 60% of their initial shock absorption capacity. No differences in shock absorption characteristics were apparent based upon either shoe price or the manufacturer model. The results of shoes tested by the volunteer runners also showed a marked reduction in shock absorption with mileage. The loss, however, was not as great as in the machine-simulated running, with approximately 70% of initial shock absorption retained at 500 miles.

In brief: Twelve members of a professional ballet company were evaluated for laxity of the knee joint. They also underwent a test of knee joint position sense. A group of 12 healthy, active, age-matched controls were similarly tested. All of the dancers met the criteria for loose joints, while only one of the control group had loose joints. In the test of joint position sense the dancers did consistently worse than controls (p <.03) and showed a significant tendency to overestimate the angle to which their knee joint had been passively moved. The authors concluded that decreased position sense may indicate below normal protective reflexes, which may increase the chances of acute or chronic injury.

We prospectively determined the risk of initial stinger experience in a group of college football players while considering the presence of cervical canal stenosis and each player's position, playing time, and body type. Prospective analysis revealed a 7.7% incidence of initial stinger experience. The average Torg ratio for all players was 0.924 +/- 0.122, with the seventh cervical level being the narrowest. Initial stinger experience depended on position played and body type. The Torg ratio did not influence initial stinger occurrence. Players who experienced multiple stingers, however, had significantly smaller Torg ratios than players experiencing only one stinger (0.75 versus 0.87). A Torg ratio of 0.70 may be a more statistically and clinically appropriate threshold for determining significant cervical stenosis and advising collegiate athletes of their risk of experiencing recurrent stingers.

The current study compared patella tracking during simulated concentric and eccentric quadriceps contractions in 12 knees from cadavers using a three-dimensional electromagnetic tracking system. The patella shifted (translated) and tilted medially during approximately the initial 22 degrees tibiofemoral flexion. The patella then shifted and tilted laterally for the remaining arc of tibiofemoral flexion (90 degrees). At 90 degrees tibiofemoral flexion, the patella had an orientation of lateral patella shift and lateral patella tilt. Patella shift was significantly more lateral between 40 degrees and 70 degrees tibiofemoral flexion during concentric quadriceps action than during eccentric contraction. Patella tilt was significantly more lateral between 45 degrees and 55 degrees tibiofemoral flexion during concentric quadriceps contraction than during eccentric action. No other significant differences were seen between the quadriceps contraction conditions. The current study supports the hypothesis that patellar instability is most likely a result of various anatomic and physiologic factors causing a failure of the extensor mechanism to deliver the patella into the femoral sulcus and that a patellar dislocation rarely would occur in a normal knee.