preoperative three-dimensional planning of screw length is not reliable in osteotomies of the humerus and forearm

Objectives: pediatric upper extremity fractures are seen frequently and sometimes lead to malunion. three-dimensional (3d) surgery planning is an innovative addition to surgical treatment for the correction of post-traumatic arm deformities. the detailed planning in three dimensions allows for optimization of correction and provides planning of the exact osteotomies which include the advised material for correction and fixation. however, no literature is available on the precision of this computerized sizing of implants and screws. this study aimed to investigate the differences between 3d planned and surgically implanted screws in patients with a corrective osteotomy of the arm.methods: planned and implanted screw lengths were evaluated in patients who underwent a 3d planned corrective osteotomy of the humerus or forearm using patient-specific 3d printed drill- and sawblade guides. postoperative information on implanted hardware was compared to the original planned screw lengths mentioned in the 3d planned surgery reports.results: of the 159 included screws in 17 patients, 45% differed >1 mm from the planned length (p<0.001). aberrant screws in the radius and ulna were often longer, while those in the humerus were often shorter. most aberrant screws were seen in the proximity of the elbow joint.conclusion: this study showed that 3d-planned screws in corrective osteotomies of the humerus and forearm differ significantly from screw lengths used during surgery. this illustrates that surgeons should be cautious when performing osteotomies with 3d techniques and predefined screw sizes.        level of evidence: iv