Goyal Nitin, Coutinho Dominic, Ghodadra Anish, Baratz Mark E, Kaufmann Robert A
Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, PA, USA.
Department of Radiology, University of Pittsburgh Medical Center, PA, USA.
Hand (N Y). 2025 Mar;20(2):284-290. doi: 10.1177/15589447231184894. Epub 2023 Jul 17.
Intramedullary screw fixation of the proximal ulna can be used for fixation of the ulnar component in total elbow arthroplasty. Our purpose was to use computed tomography (CT) to characterize proximal ulna anatomy with respect to intramedullary screw fixation, and then to validate this templating process by inserting intramedullary screws into 3-dimensional (3D)-printed models.
Thirty elbow CT scans were reformatted in the axis of the proximal ulna. Screw placement was templated by fixing a length at 78 mm distal to the centerline of ulnohumeral rotation and measuring diameter, and then fixing the screw pitch diameter to 5.5 mm and measuring length. Three-dimensional models were printed for 5 patients, and intramedullary screws were advanced as distal as possible until endosteal fit was achieved.
All patients had an anatomic limit for intramedullary screw fixation, due to dorsal angulation, varus angulation, or both. At 78 mm distal to the centerline of rotation, mean screw diameter was 5.4 mm (range, 3.2-8.0). When fixing screw diameter to 5.5 mm, the mean screw length was 79.9 mm (range, 64.2-107.9). All intramedullary screws were placed in the 3D models within 3 mm of the templated length, with correlation coefficient 0.992.
This study characterized proximal ulna anatomy in the context of intramedullary screw fixation. Templating allows surgeons to predict intramedullary screw sizing, and a broad range of screw lengths and diameters is required when attempting intramedullary screw fixation for placement of the ulnar component in uncemented total elbow arthroplasty.
尺骨近端髓内螺钉固定可用于全肘关节置换术中尺骨部件的固定。我们的目的是使用计算机断层扫描（CT）来描述尺骨近端在髓内螺钉固定方面的解剖结构，然后通过将髓内螺钉插入三维（3D）打印模型来验证这种模板制作过程。
对30例肘关节CT扫描图像进行尺骨近端轴线方向的重新格式化。通过在尺肱旋转中心线远端78毫米处固定一个长度并测量直径来进行螺钉置入模板制作，然后将螺钉节径固定为5.5毫米并测量长度。为5例患者打印三维模型，并将髓内螺钉尽可能向远端推进，直至达到骨内膜贴合。
由于背侧成角、内翻成角或两者皆有，所有患者在髓内螺钉固定方面都存在解剖学限制。在旋转中心线远端78毫米处，平均螺钉直径为5.4毫米（范围为3.2 - 8.0毫米）。当将螺钉直径固定为5.5毫米时，平均螺钉长度为79.9毫米（范围为64.2 - 107.9毫米）。所有髓内螺钉在3D模型中的置入长度与模板长度相差在3毫米以内，相关系数为0.992。
本研究描述了在髓内螺钉固定背景下的尺骨近端解剖结构。模板制作可使外科医生预测髓内螺钉尺寸，在非骨水泥型全肘关节置换术中尝试进行尺骨部件髓内螺钉固定时，需要广泛的螺钉长度和直径范围。
