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Background:A previous cross-sectional study reported that pathogenic factors associated with Osgood-Schlatter disease (OSD) in adolescent athletes include increased quadriceps muscle tightness, lower leg malalignment, and development of apophysitis in the tibial tuberosity.Purpose:To confirm these pathogenic factors associated with OSD in a longitudinal study with regard to physical function and performance.Study Design:Cohort study; Level of evidence, 2.Methods:In this study, 37 boys (mean age, 10.2 ± 0.4 years) were recruited from 2 soccer teams at an elementary school. This cohort study was conducted over an observation period of 1 year, with measurements recorded at baseline, followed by screening for OSD every 6 months. Variables evaluated at baseline included physical function (morphometry, joint flexibility, and lower extremity alignment), presence of Sever disease, and kicking motion.Results:Pathogenic factors associated with OSD in the support leg of adolescent male soccer players included height, weight, body mass index, quadriceps femoris muscle tightness in the kicking and support legs, and gastrocnemius muscle tightness, soleus muscle tightness, and medial longitudinal arch in the support leg. Additional factors included a diagnosis of Sever disease and distance from the lateral malleolus of the support leg’s fibula to the center of gravity during kicking.Conclusion:The onset of OSD was found to be affected by many factors, including developmental stage, physical attributes, and pre-existing apophysitis. In particular, a diagnosis of Sever disease and backward shifting of the center of gravity during kicking increased the risk of the subsequent onset of OSD, suggesting that these factors are very important as a possible focus for interventions.

Rhodococcus equi was isolated from the lungs of six foals with bronchopneumonia. All isolates expressed 15-17-kd antigens by immunoblot analysis and contained a virulence-associated plasmid of 85 or 90 kb. Immunohistochemically, R. equi from all pulmonary lesions showed the expression of 15-17-kd antigens mainly in the phagocytic cells. The specific monoclonal antibody to 15-17-kd antigens of R. equi (MAb 10G5) may be an aid in the diagnosis of R. equi-induced pneumonia.

One hundred and eight foals were necropsied and examined for Rhodococcus equi infection from 1992 to 1998 in Hokkaido and

ABSTRACT. Although isolation of Rhodococcus equi from tracheobronchial aspirates is thought to be a definitive diagnosis of R. equi pneumonia in foals, virulence of isolates from the aspirates of infected foals remains obscure. In the present study, transtracheal aspirates were collected from thirty-one 1-to 6-month-old foals, which showed clinical signs of respiratory tract infection, and R. equi isolates were analyzed for the presence of virulence plasmids and virulence-associated antigens. Moreover, this method was compared with a serodiagnosis by an enzyme-linked immunosorbent assay (ELISA) to evaluate the sensitivity of the ELISA. Of the 31 foals, 21 revealed positive cultures for R. equi. Of the 21 foals, 20 (95%) had an ELISA OD value of 0.3 (positive limit of this test) or higher at the initial medical examination. All of the isolates from the aspirates were virulent R. equi, which contained virulence plasmids and expressed virulence-associated antigens. In the remaining 10 foals showing a negative culture for R. equi, 3 foals had positive ELISA titers. Six foals died during the treatment, and necropsy revealed that 5 of the 6 foals had R. equi infection characterized by large abscesses in the lungs, and 3 of the 5 foals also had intestinal lesions. All clinical isolates from the lesions of the foals were virulent R. equi. These results support the assumption that isolates from the transtracheal aspirates of infected foals are virulent R. equi and the sensitivity of ELISA might demonstrate a serodiagnostic value for early diagnosis of R. equi infection in foals. -KEY WORDS: foal, Rhodococcus equi, tracheal aspirate, virulence.

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Osgood-Schlatter disease is the most common type of knee joint injury among adolescent male soccer players. To clarify the cause of Osgood-Schlatter disease in adolescent soccer players, we previously measured the position of the center of gravity during the kicking motion. It was revealed that the center of gravity during the kicking motion was backward in soccer players who developed Osgood-Schlatter disease. The purpose of the present study was to develop a taping method (prevention tape) to prevent backward center of gravity during the kicking motion and therefore to prevent the onset of Osgood-Schlatter disease. The participants recruited for this study were 36 boys from two soccer teams of an elementary school, with a mean age of 10.2 ± 0.4 years. The three-dimensional coordinates of the markers were calculated using a three-dimensional video motion analysis system. The center of gravity was measured by Yokoi's method, using body part coefficients. A net was set up 3m away from the ball and 1m above the ground in order to measure the kicking motion. When applying the prevention tape, the patella was pulled downward by the traction force of the tape. We investigated the difference in the position of the center of gravity during kicking motion with or without prevention tape. In adolescent soccer players with prevention tape during the kicking motion, center of gravity changed to be significantly more forward than that in players without prevention tape.