Abstract

Background
The study was conducted to determine the practical area for inserting the coracoclavicular (CC) screw through the plate by analyzing three-dimensional (3D) shoulder models featuring virtually implanted, actual-size plates and screws.
Methods
Ninety cadaveric shoulders (41 males and 49 females) underwent continuous 1.0-mm slice computed tomography scans. The scan data were imported into image-processing software to generate a 3D shoulder model, including the scapula and clavicle. The overlapping area between the clavicle and the horizontal portion of the coracoid process (horizontal portion_CP) was analyzed in the cranial view. A curved pelvic recon plate was virtually placed on the upper surface of the distal clavicle, and an actual-size (3.5 mm) CC screw was inserted through the plate. Anatomic features were assessed.
Results
The distal clavicle directly overlapped with the horizontal portion_CP in the vertical direction. The overlapping area was sufficient to place the 3.5 mm and 4.5 mm-sized screws. In all shoulder models, the CC screw could be inserted through the plate into the vertical direction, with an average length of 35.5 mm (range, 26.2‒62.5 mm; standard deviation, 1.2 mm). In 87 models, the CC screw was inserted through the third hole from the lateral end of the plate. Two models were inserted through the second hole, and one model through the fourth hole.
Conclusion
The upper surface of the clavicle has sufficient overlapping area to place CC screws through the plate in the vertical direction in the corresponding hole. Supplemental CC screw fixation through the plate can be performed without additional or special equipment. Level of evidence: IV

• Keywords: Distal clavicle; Bone fractures; Coracoclavicular screw fixation; Three-dimensional modeling