The utility of the KJOC score in professional baseball in the United States.

BACKGROUND

The Kerlan-Jobe Orthopaedic Clinic (KJOC) Shoulder and Elbow questionnaire has been shown by previous studies to be more sensitive than other validated subjective measurement tools in the detection of upper extremity dysfunction in overhead-throwing athletes.

PURPOSE

The primary objective was to establish normative data for KJOC scores in professional baseball players in the United States. The secondary objectives were to evaluate the effect of player age, playing position, professional competition level, history of injury, history of surgery, and time point of administration on the KJOC score.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

From 2011 to 2012, a total of 203 major league and minor league baseball players within the Houston Astros professional baseball organization completed the KJOC questionnaire. The questionnaire was administered at 3 time points: spring training 2011, end of season 2011, and spring training 2012. The KJOC scores were analyzed for significant differences based on player age, injury history, surgery history, fielding position, competition level, self-reported playing status, and time point of KJOC administration.

RESULTS

The average KJOC score among healthy players with no history of injury was 97.1 for major league players and 96.8 for minor league players. The time point of administration did not significantly affect the final KJOC score (P = .224), and KJOC outcomes did not vary with player age (r = -0.012; P = .867). Significantly lower average KJOC scores were reported by players with a history of upper extremity injury (86.7; P < .001) and upper extremity surgery (75.4; P < .0001). The KJOC results did vary with playing position (P = .0313), with the lowest average scores being reported by pitchers (90.9) and infielders (91.3).

CONCLUSION

This study establishes a quantitative baseline for the future evaluation of professional baseball players with the KJOC score. Age and time of administration had no significant effect on the outcome of the KJOC score. Missed practices or games within the previous year because of injury were the most significant demographic predictors of lower KJOC scores. The KJOC score was shown to be a sensitive measurement tool for detecting subtle changes in the upper extremity performance of the professional baseball population studied.