Objective: To compare the performance of three guided humeral transcondylar drilling techniques and the freehand drilling technique based on anatomical landmarks.
Study design: Randomized block design ex vivo study.
Sample population: Canine cadavers (n = 48; 96 elbows).
Methods: Elbows were scanned using computed tomography (CT) to manufacture patient-specific three-dimensional (3D)-printed drill guides (3D-PDG) and were randomly assigned to one of four groups: universal aiming device (UAD), fluoroscopy-assisted drilling (FAD), 3D-PDG, and freehand drilling (FHD) performed by two board-certified surgeons. All elbows were CT scanned. Drilled tunnels (DT) were compared with an optimal drilling axis (ODA). Outcome measures included drilling time, DT entry and exit point translations, angulation, distance to the articular surface, and joint infringement.
Results: Drilling technique influenced both entry and exit point translation. Freehand drilling was the fastest and safest method (0% joint infringement). The UAD exhibited the highest incidence of joint infringement (26.1%), followed by 3D-PDG (21.7%) and FAD (4.2%). Most joint infringements were caused by unacceptable (>10°) craniocaudal or proximodistal DT angulation.
Conclusion: When performed by experienced surgeons, FHD is accurate and safe, and may outperform guided techniques. Laterally applied 3D-PDG necessitates specific design modifications to improve stability, as well as surgeon training and feedback. The UAD technique may be adversely affected by the lack of a surgical assistant and by limb position. Fluoroscopy-assisted drilling is accurate, but it results in a longer procedure time and requires equipment that may not be readily accessible.
Clinical significance: Experienced surgeons can reliably perform FHD utilizing anatomical landmarks with satisfactory accuracy for humeral condylar drilling.
