Abstract
Objectives:
Injuries to the shoulder and elbow continue to be a problem in overhead athletes. To our knowledge, it has not yet been shown how the bony anatomy measured on physical exam, specifically valgus carrying angle at the elbow (VCA), correlates with injury risk. It is known that athletes commonly have an increased VCA thought to be secondary to adaptive changes due to repetitive stress. The purpose of our study was to prospectively determine whether the presence of an increased dominant arm (D) VCA is correlated with the onset of shoulder and elbow injuries.
Methods:
The VCA and elbow flexion contracture (EFC) along with passive range of motion of the glenohumeral joint for D and non-dominant (ND) arms were assessed for all pitchers and position players participating in spring training for three minor league baseball teams for the 2016 season. Investigators performed examinations on a total of 61 athletes (34 pitchers, 27 position players). Any shoulder and/or elbow injury necessitating treatment was recorded during the season by the medical staff and defined as an injury. Using VCA as the predictor variable, we estimated the odd ratio of shoulder and elbow injuries in pitchers from a binary logistic regression model.
Results:
The mean D VCA for pitchers was 13.6° versus 11.1° for players (p=0.04). The mean D EFC was 5.4° for pitchers and 4.8° for position players (p=0.76). No significant differences were noted when comparing D ER, D IR, and D F (Table 2). In addition, a higher mean D VCA was noted in older/more experienced players (14.5° versus 10.9°, p=0.026). There were 10 shoulder and/or elbow injuries with 8 occurring in pitchers. A greater mean VCA was noted for injured pitchers compared with non-injured pitchers (17.5 +/- 4.2 versus 13.1 +/- 5.2). Using logistic regression, a significant association between D VCA and injury was noted. Pitchers with an increased D VCA had a 1.25 times greater odds for injury (P = 0.040; 95% CI, 0.98, 1.59).
Conclusion:
Increased VCA on the throwing side increased the likelihood of a shoulder/elbow injury in pitchers. Additionally, we noted a significant increased mean D VCA in pitchers compared to position players as well as an increased mean D VCA in older/more experienced players. Understanding a relationship between the throwing motion and osseous anatomy may give us further insight into the etiology of shoulder/elbow injuries. Sports medicine clinicians should be aware of this study’s results and develop a plan that addresses this issue in an effort to deter shoulder/elbow injuries in pitchers.
Spring Training Measurments, Data obtained from both dominant (D) and non-dominant (ND) arms for valgus carrying angle (VCA), total rotation motion (TRM), elbow flexion contractures (EFC), internal rotation (IR), and external rotation (ER). All measurements were in degrees.
| Pitchers n=34 | Position n=27 | P-Value | |
|---|---|---|---|
|
|
27.8 | 29.0 | 0.302 |
|
|
74.0 | 71.7 | 0.004 |
|
|
208.4 | 198.2 | 0.048 |
|
|
8.3 | 8.3 | 0.953 |
|
|
13.6 | 11.1 | 0.043 |
|
|
12.2 | 12.2 | 0.987 |
|
|
154.1 | 147.3 | 0.074 |
|
|
157.6 | 150.0 | 0.051 |
|
|
8.8 | 8.6 | 0.887 |
|
|
5.4 | 4.8 | 0.764 |
|
|
0.5 | 2.1 | 0.080 |
|
|
161.6 | 162.2 | 0.767 |
|
|
167.7 | 161.7 | 0.015 |
|
|
31.8 | 29.0 | 0.300 |
|
|
47.5 | 41.6 | 0.049 |
|
|
122.3 | 118.3 | 0.127 |
|
|
110.2 | 108.5 | 0.512 |
Dominant Valgus Carrying Angle at the elbow (VCA) distribution among injured and non-injured pitchers