A New Versatile Mandibular Stabilisation and Transport Distraction System for Treating Segmental Defects of the Mandible (AMSTDS)

Many types of distraction devices currently exist for mandibular regeneration. These devices are both extraoral and intraoral in configuration. All of these rely on a system of distraction clamps which are mounted on a straight line distraction rod. These distractors hence by design regenerate bone in a straight line vector which does not favour the curved architecture of the mandible.^1,2 A new mandibular distraction system has been designed which addresses these issues and allows bone regenerate in all the three axes besides also helps in stabilisation of the segmentally deficient mandible in an anatomical position. 

 

This system has an elliptical, threaded, curved rod which conforms to the shape of the human mandible. Mandibular stabilization and bone transport are accomplished with the help of different assemblies that are attached on to this central rod. The first assembly is the stabilization assembly which helps in the rigid fixation of the frame to the mandible thereby stabilizing the mandible securely. The bone transport assembly consists of one or two moveable clamp assemblies which are fixed at one end to the bone while the base unit of this assembly glides and engages on the threads of the distraction rod. The third assembly is the multivector distraction assembly which is also mobile at one end on the distraction rod while the other end is anchored to the mandible through incorporation of distraction rod and 360⁰  swivel joint. This arrangement allows mandibular distraction in the vertical and transverse axes in addition to the horizontal mandibular distraction performed by the bone transport assembly.

 

The device has been used in five patients with mandibular segemental defects in excess of 6.0 cm. Satisfactory mandibular regenerate in optimal curvilinear vector has been obtained. The regenerate has consolidated well. There have been no device failures and patients have been comfortable performing the distraction by themselves.

 

The present device has been found effective for performing stabilisation and simultaneous reconstruction of the mandible by transport distraction.

 

References

 

1. Stucki-McCormick, S.U. Reconstruction of the mandibular condyle using transport distraction osteogenesis. J Craniofac Surg. 8:48-52, 1997.

 

2. Sawaki Y, Hagino H, Yamamato & Ueda m. Trifocal distraction osteogenesis for segmental mandibular defect: a technical innovation. J Craniomax Surg 1997; 25(6), 310-315.