Swing Type and Batting Grip Affect Peak Pressures on the Hook of Hamate in Collegiate Baseball Players

Abstract

Background: Bat swing and grip type may contribute to hook of hamate fractures in baseball players. Purpose: To compare the effects of swing type and batting grip on the pressure and rate of pressure development over the hook of hamate in collegiate baseball players. Study Design: Descriptive laboratory study. Level of evidence, 3. Methods: This was an experimental quasi-randomized study of bat grip and swing differences in National Collegiate Athletic Association Division I baseball players (N = 14; age, 19.6 ± 1.1 years [mean ± SD]). All participants performed swings under 6 combinations: 3 grip types (all fingers on the bat shaft [AO], one finger off the bat shaft [OF], and choked up [CU]) and 2 swing types (full swing and check swing). Peak pressure and rate of pressure generation over the area of the hamate were assessed using a pressure sensor fitted to the palm of the bare hand over the area of the hamate. Wrist angular velocities and excursions of radial ulnar deviation were obtained using 3-dimensional motion analysis. Results: The OF–check swing combination produced the highest peak pressure over the hamate (3.72 ± 2.64 kg/cm2) versus the AO–full swing (1.36 ± 0.73 kg/cm2), OF–full swing (1.68 ± 1.17 kg/cm2), and CU–full swing (1.18 ± 0.96 kg/cm2; P < .05 for all). There was a significant effect of condition on rate of pressure development across the 6 conditions ( P = .023). Maximal wrist angular velocities were 44% lower in all check swing conditions than corresponding full swing conditions ( P < .0001). The time to achieve the maximal wrist angular velocity was longest with the AO–full swing and shortest with the CU–check swing (100.1% vs 7.9% of swing cycle; P = .014). Conclusion: The OF–check swing condition produced the highest total pressure reading on the hook of hamate. Check swing conditions also had the steepest rate of pressure development as compared with the full swing conditions. Clinical Relevance: Batters who frequently check their swings and use an OF or AO grip may benefit from bat modifications or grip adjustment to reduce stresses over the hamate. Athletic trainers and team physicians should be aware of these factors to counsel players in the context of previous or ongoing hand injury.