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Published on: August 14, 2018
Force-sensing drill-through detection and automatic stopping in a porcine distal humerus model simulating pediatric
Kunzhi Zhu1,2, Juxiang Huang3, Gang Chen3
1Guizhou Medical University, Guiyang, China.
Insights
A new force-sensing drill system significantly reduced overdrilling during pediatric fracture fixation, limiting K-wire advancement to approximately 1mm. This technology enhances safety by minimizing risks to adjacent neurovascular structures.
Area of Science:
- Orthopedic surgery
- Biomedical engineering
- Surgical technology
Background:
- Supracondylar humeral fractures are common pediatric elbow injuries.
- Percutaneous Kirschner wire (K-wire) fixation is a standard treatment.
- Overdrilling during K-wire fixation can damage adjacent neurovascular structures.
Purpose of the Study:
- To evaluate a novel force-sensing drill-through stopping system.
- To assess the system's effectiveness in limiting overdrilling in a porcine humerus model.
- To determine the impact of feed rate and spindle speed on overdrill depth.
Main Methods:
- A force-sensing system with a six-axis force/torque sensor was used to detect far-cortex breakthrough via a transient force drop.
- Porcine humeri were drilled with a 2.0-mm K-wire, testing various feed rates and spindle speeds.
- Overdrill depth was measured, and robotic drilling was compared to manual drilling by a surgeon.
Main Results:
- The force-sensing system limited overdrill depth to approximately 1 mm.
- Higher feed rates (1.5 mm/s) increased overdrill depth compared to lower rates (0.5 mm/s).
- Spindle speed did not significantly affect overdrill depth.
- The robotic system reduced overdrilling by 86.8% compared to manual drilling (0.87 mm vs. 6.60 mm).
Conclusions:
- The force-sensing drill-through stopping system effectively minimizes overdrilling in a porcine model.
- This technology shows potential for increasing safety during percutaneous pinning by reducing the risk of neurovascular injury.
- Further clinical studies are recommended to validate these findings in human patients.
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 six-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.
