Skull Clamp Application: A Safe, Team-based Approach and Literature Review

Land, Charles F.; Bowden, Blake D.; Callaway, L. Fielding; Henderson, Andrew; DeVine, John G.

doi:10.1097/bto.0000000000000397

Cited by 2 publications

(2 citation statements)

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“…Even if there would be a linear relation between skull thickness and strength, a 3.2 mm pediatric skull should be able to resist 500 N axial force which corresponds to a torque of about 0.7 Nm (6 in-lb). A more practical approach to determine the safety of this axial load in the same temporal area in children is to consider currently used forces with the Mayfield clamp (Integra life sciences France) that is positioned similarly [15]. The adjustable pin is typically loaded to max 260 N (60 lbs) in children, although a special pediatric version is available with a maximal axial load of about 80 N (18 lbs) [23].…”

Section: Discussionmentioning

confidence: 99%

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Halo pin positioning in the temporal bone; parameters for safe halo gravity traction

et al. 2020

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Introduction Halo gravity traction (HGT) is increasingly used pre-operatively in the treatment of children with complex spinal deformities. However, the design of the current halo crowns is not optimal for that purpose. To prevent pin loosening and to avoid visual scars, fixation to the temporal area would be preferable. This study aims to determine whether this area could be safe for positioning HGT pins. Methods A custom made traction setup plus three human cadaver skulls were used to determine the most optimal pin location, the resistance to migration and the load to failure on the temporal bone. A custom-made spring-loaded pin with an adjustable axial force was used. For the migration experiment, this pin was positioned at 10 predefined anatomical areas in the temporal region of adult cadaver skulls, with different predefined axial forces. Subsequently traction force was applied and increased until migration occurred. For the load-to-failure experiment, the pin was positioned on the most applicable temporal location on both sides of the skull. ResultsThe most optimal position was identified as just antero-cranial to the auricle. The resistance to migration was clearly related to the axial tightening force. With an axial force of only 100 N, which corresponds to a torque of 0.06 Nm (0.5 in-lb), a vertical traction force of at least 200 N was needed for pin migration. A tightening force of 200 N (torque 0.2 Nm or 2 in-lb) was sufficient to resist migration at the maximal applied force of 360 N for all but one of the pins. The load-to-failure experiment showed a failure range of 780-1270 N axial force, which was not obviously related to skull thickness. ConclusionThe temporal bone area of adult skulls allows axial tightening forces that are well above those needed for HGT in children. The generally applied torque of 0.5 Nm (4 in-lb) which corresponds to about 350 N axial force, appeared well below the failure load of these skulls and much higher than needed for firm fixation.

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Section: Discussionmentioning

confidence: 99%

“…Based on literature research and a design cycle we determined that the most optimal design would consist of an arch similar to a Gardner tong or Mayfield clamp [13][14][15]. This better allows a continuous and self-correcting force on the skull pins, obviates the need for frontal pins and easily aligns with gravity.…”

Section: Introductionmentioning

confidence: 99%