Department of Orthopedics, Balgrist University Hospital, University of Zürich, Forchstrasse 340, 8008, Zürich, Switzerland.
BMC Musculoskelet Disord. 2022 Jun 2;23(1):527. doi: 10.1186/s12891-022-05480-w.
A retrospective, single center, data analysis.
Persistent pain and instability are common complications after distal ulnar head arthroplasty. One main reason may be the insufficient representation of the anatomical structures with the prosthesis. Some anatomical structures are neglected such as the ulnar head offset and the ulnar torsion which consequently influences the wrist biomechanics.
CT scans of the ulnae of forty healthy and asymptomatic patients were analyzed in a three-dimensional surface calculation program. In the best fit principle, cylinders were fitted into the medullary canal of the distal ulna and the ulnar head to determine their size. The distance between the central axes of the two cylinders was measured, which corresponds to the ulnar offset, and also their rotational orientation was measured, which corresponds to the ulnar torsion.
The mean medullary canal diameter was 5.8 mm (±0.8), and the ulnar head diameter was 15.8 mm (±1.5). The distance between the two cylinder axes was 3.89 mm (±0.78). The orientation of this offset was at an average of 8.63° (±15.28) of supination, reaching from 23° pronation to 32° supination.
With these findings, a novel ulnar head prosthesis should have different available stem and head sizes but also have an existing but variable offset between these two elements. A preoperative three-dimensional analysis is due to the high variation of offset orientation highly recommended. These findings might help to better represent the patients natural wrist anatomy in the case of an ulnar head arthroplasty.
III.
回顾性、单中心、数据分析。
桡骨远端小头置换术后持续性疼痛和不稳定是常见并发症。一个主要原因可能是假体对解剖结构的代表性不足。一些解剖结构被忽略，如桡骨小头偏移和桡骨扭转，这会影响腕部生物力学。
对 40 名健康无症状患者的尺骨进行 CT 扫描，并在三维表面计算程序中进行分析。在最佳拟合原理下，将圆柱体拟合到尺骨远端和桡骨小头的髓腔中，以确定其大小。测量两个圆柱体中心轴之间的距离，该距离对应桡骨小头偏移，也测量它们的旋转方向，该方向对应桡骨扭转。
平均髓腔直径为 5.8mm（±0.8），桡骨小头直径为 15.8mm（±1.5）。两个圆柱体轴之间的距离为 3.89mm（±0.78）。这个偏移的方向平均为 8.63°（±15.28）的旋前，从 23°旋前到 32°旋前。
根据这些发现，新型桡骨小头假体应该具有不同的可用柄部和头部尺寸，但这两个部件之间也应该存在现有但可变的偏移。由于偏移方向的高度变化，术前的三维分析是高度推荐的。这些发现可能有助于在桡骨小头置换术中更好地代表患者的自然腕部解剖结构。
III。
