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Force-sensing drill-through detection and automatic stopping in a porcine distal humerus model simulating pediatric supracondylar pinning

Year: 2026

Type: article

Abstract: Background Supracondylar humeral fractures are the most common elbow fractures in children and are often treated with closed reduction and percutaneous Kirschner wire (K-wire) fixation. After far-cortex breach, delayed stopping can cause overdrilling and jeopardize adjacent neurovascular structures. We evaluated a force-sensing drill-through stopping system in a porcine humerus model and assessed the effects of feed rate and spindle speed on overdrill depth. Methods Porcine distal humeri were drilled with a 2.0-mm K-wire introduced through the lateral condyle at ∼60° to the humeral longitudinal axis. A si x -axis force/torque sensor measured axial force; a transient force drop triggered an automatic stop command. Overdrill depth was the distance the K-wire tip advanced beyond the outer surface of the far cortex. Parameter tests compared feed rates (0.5/1.0/1.5 mm·s − ¹ at 1,200 r min − ¹) and spindle speeds (900/1,200/1,500 r min − ¹ at 1.0 mm s − ¹). Robotic vs. manual drilling was evaluated in paired tests at adjacent, non-interfering sites; manual drilling was performed by a senior pediatric orthopedic surgeon using tactile feedback. Statistical analysis used repeated-measures one-way ANOVA with Geisser–Greenhouse correction and Tukey post hoc tests, and paired t-tests ( α = 0.05). Results Feed rate significantly affected overdrill depth (Geisser–Greenhouse corrected, p = 0.016); 1.5 mm·s − ¹ produced greater overdrill depth than 0.5 mm·s − ¹ (Δ = 0.252 mm, adjusted p = 0.0456). Spindle speed had no significant effect ( p = 0.900). In paired comparisons, the robotic system reduced overdrilling from 6.60 ± 1.53 mm (manual) to 0.87 ± 0.12 mm (robotic) (mean paired difference 5.73 mm, 95% CI 4.67–6.80; p < 0.0001), an 86.8% reduction. Conclusions The force-sensing drill-through stopping system limited overdrill depth to approximately 1 mm in a porcine humerus model. Within the tested range of 900–1,500 r·min − ¹ and 0.5–1.5 mm·s − ¹, higher feed rates produced a modest increase in overdrilling whereas spindle speed had no significant effect. Compared with manual drilling, the system substantially reduced overdrill depth (≈1 mm vs. 6.6 mm), suggesting potential safety advantages during percutaneous pinning by limiting overdrilling and thereby increasing the safety margin after far-cortex breakthrough. Clinical studies are warranted to determine whether this translates into fewer neurovascular complications.

Source: Frontiers in Pediatrics

DOI: 10.3389/fped.2026.1780738