Momma Daisuke, Iwasaki Norimasa, Oizumi Naomi, Fujisaki Kazuhiro, Funakoshi Tadanao, Abe Yuichiro, Kamishima Tamotsu, Tadano Shigeru, Minami Akio
Department of Orthopaedic Surgery, Hokkaido University School of Medicine, Kita 15, Nishi 7, Kita-ku, Sapporo, 060-8638, Japan.
J Orthop Sci. 2012 May;17(3):253-60. doi: 10.1007/s00776-012-0198-8. Epub 2012 Feb 10.
The distribution of subchondral bone density well reflects long-term resultant stress acting on an articular surface in living joints. Consequently, a measurement of the distribution pattern can determine the stress distribution across the elbow joint surface under long-term loading conditions of baseball pitching. Our purpose was to elucidate the characteristic alterations in the distribution pattern of subchondral bone density across the forearm bones of the elbow with pitching activities. The hypothesis is that pitching activities would change the stress distribution in living subjects.
The analysis was performed using computed tomography (CT) images obtained from the dominant elbow of ten nonthrowing athletes (control group), ten college baseball fielders (fielder group), and ten college baseball pitchers (pitcher group). The distribution pattern of subchondral bone density through the articular surface of the proximal radius and ulna bones was assessed using CT osteoabsorptiometry.
The maximum density area was located in the posterior part of the trochlea notch in all study participants. This maximum density area was significantly increased in the baseball groups compared with that in the control group. The pitcher group also showed a significant distribution of the maximum density area in the anterior part of the radial head.
Our analysis indicates that pitching activities increase actual stress on the articular surface not only in the posterior part of the trochlea notch but also in the anterior part of the radial head. The stress across the elbow may be expanded from the ulnohumeral to the radiohumeral joint by repetitive pitching activities in living subjects.
软骨下骨密度的分布能很好地反映作用于活体关节关节面的长期合成应力。因此，对分布模式的测量可以确定在棒球投球的长期负荷条件下肘关节表面的应力分布。我们的目的是阐明投球活动时肘关节前臂骨软骨下骨密度分布模式的特征性变化。假设是投球活动会改变活体受试者的应力分布。
使用从10名非投掷运动员（对照组）、10名大学棒球外野手（外野手组）和10名大学棒球投手（投手组）的优势肘关节获得的计算机断层扫描（CT）图像进行分析。使用CT骨吸收测定法评估桡骨近端和尺骨近端关节面软骨下骨密度的分布模式。
所有研究参与者的最大密度区域位于滑车切迹的后部。与对照组相比，棒球组的这个最大密度区域显著增加。投手组在桡骨头前部也显示出最大密度区域的显著分布。
我们的分析表明，投球活动不仅增加了滑车切迹后部关节面的实际应力，也增加了桡骨头前部关节面的实际应力。在活体受试者中，通过重复投球活动，肘关节的应力可能从尺肱关节扩展到桡肱关节。
