Auto Strut: A novel smart robotic system for external fixation device for bone deformity correction, a preliminary experience

Abstract

Purpose Several hexapod external fixators are used in the treatment of bone fracture and deformity corrections. One characteristic of all of them is the requirement for manual adjustment of the fixator struts. The purpose of this study was to introduce a novel robotic system that executes automatic adjustment of the struts. Methods Ten patients were treated for various bone deformities using a hexapod external fixator with the Auto Strut system. This new system automatically adjusts the fixator struts according to a hexapod computer-assisted correction plan. During each visit, the progress of the correction was assessed (clinically and radiographically) and reading of the strut scale numbers was performed and compared with the original treatment plan. Results All patients completed treatment during the follow-up period, achieving all planned correction goals, except from one patient who switched to manual struts due to personal preference. The device alarm system was activated once with no device-related adverse events. Duration of distraction ranged between ten and 90 days with a distraction index ranging between eight and 15 days/cm. Regenerate consolidation time between one and seven months. In total, 48 struts of eight patients were recorded and analyzed. In all, 94% of the final strut number readings presented a discrepancy of 0 mm to 1 mm between planned and actual readings, indicating high precision of the automatic adjustment. Conclusion This study presents preliminary results, showing that Auto Strut can successfully replace the manual strut adjustment providing important advantages that benefit the patient, the caregiver and the surgeon. Level of Evidence Level II

Combination of external fixation using digital six-axis fixator and internal fixation to treat severe complex knee deformity

“…But conventional Ilizarov external fixator is not proper for multiplanar deformities correction because it was major for lengthening and axial correction. Hexapod external fixator has been proven to be effective in multiplanar deformities correction with high precision [18,19].…”

A new ring fixator system for automated bone fixation

“…5-7, 11 A notable example is the Maxframe Autostrut system where full automatisation is achieved by adjusting the strut lengths with the installed electric motors according to the treatment recipe. 9 A path correction is proposed in the TSF frame to prevent the collision of the bony ends of the bone fragments during treatment. 32 Such approaches can be applied to the lambda fixator in the future.…”

“…2,3 It is used not only for stabilising the bone fragments in a fracture but also very convenient for the treatment of angular deformities and limb-length discrepancies. 4 Ring fixators have been the subject of many studies with regard to their usage for the treatment of specific pathologies, [5][6][7][8] their automation via supporting software 9,10 or increasing their durability. 11 Another advantage of ring fixators is that their geometry can be configured in many different ways providing flexibility in treatment.…”

What’s New in Limb Lengthening and Deformity Correction

“…Fenton et al compared the biomechanical properties of several hexapod frame constructs with the traditional Ilizarov construct and determined that the hexapod frames were more rigid under bending and torsional loading but less so under axial loading 70 . Preliminary results of deformity correction using a novel, motorized, hexapod frame revealed successful achievement of preoperative goals 71 . The device precludes the need for manual strut adjustments and thus may potentially decrease the risk of inaccurate adjustments.…”