Bony hypertrophy of the forearm in bareback rodeo athletes

Activities that require increased load bearing are known to cause bony hypertrophy. This phenomenon has been documented in the dominant arm of athletes in sports requiring significant utilization of a single limb. The literature addressing this effect in rodeo athletes, however, is minimal. Studies evaluating rodeo athletes are primarily focused on acute injury management rather than chronic symptoms resulting from changes in bone and soft tissue. We designed a study to evaluate bony hypertrophy in athletes without acute injury.

Rodeo bareback riders presented with frequent pain in their grip arm, no radiographic evidence of injury, and clinical signs of peripheral nerve compression. Anteroposterior and lateral X-rays taken for initial evaluation in 17 bareback rodeo athletes were retrospectively reviewed. The diameter of bilateral ulnas was measured at its longitudinal midpoint. Ratio of Ulnar Diameters (grip arm/free arm) and Percentage Diameter Difference were calculated. An independent samples t-test was used to assess differences in diameters of grip and non-grip arms.

The mean ulnar diameter was 18.4 ± 3.5 in the grip arm and 16.6 ± 3.5 in the non-grip arm (p < 0.001). The mean ratio of grip to free arm ulnar diameter was 1.42 ± 0.21 (range = 1.05-1.92). The mean diameter percent difference measured 42.3% (range = 4.7%-92.0%), and the grip arm was observed to have a greater ulnar diameter compared to the non-grip arm.

There are significant anatomic differences in the grip arm of bareback rodeo athletes compared to the contralateral arm. In cases of persistent pain in the grip arm and no evidence of acute injury, these differences may be relevant to pain symptoms and should be considered as part of the assessment and treatment algorithm.