Two-year follow-up study of subchondral surface irregularities of the capitellum on ultrasonography in baseball players under the age of 10 years

Objective To determine whether subchondral surface irregularities of the capitellum on ultrasonography in baseball players under the age of 10 years are indicative of early osteochondritis dissecans (OCD) of the capitellum. Materials and methods A total of 321 players aged 6–9 years underwent ultrasonographic examination, and the findings for the subchondral bone of the capitellum on the throwing side were graded as 0, 1a, 1b, 2, or 3. Subjects classified as grade 1a or 1b showed irregularities of the subchondral bone surface and were investigated radiographically for OCD. All players continued to throw and were re-examined by ultrasonography after 1 and 2 years. Results At the first examination, 11/321 (3.4%) had irregularities at the subchondral surface of the capitellum [grade 1a in 7/321 (2.2%); grade 1b in 4/321 (1.2%)]. The seven players with grade 1a showed no evidence of OCD or Panner’s disease on radiography and were reclassified as grade 0 at the 2-year follow-up. All four players with grade 1b were reclassified as grade 0 at follow-up 1 and 2 years later. Conclusion Subchondral bone surface irregularities of the capitellum on ultrasonography in children under the age of 10 years may not be indicative of disease, but rather represent variation of ossification during normal development.