METS Modular Implants

Custom JTS Non Invasive Extendible Prostheses

In the mid 1980ís, Professor John T. Scales (FRCS) of The Centre for Biomedical Engineering and Mr Rodney Sneath (FRCS) a leading orthopaedic oncology surgeon, originated the concept of the non invasive extendible implant.

(For the patient and parent specific JTS Implant website please click here.)

JTS (juvenile tumour system) implantAt its core, the JTS implant is lengthened by a small yet powerful gearbox, which drives the extension. Remarkably, the gearbox is able to output ample force to lengthen the limb via a speed reduction ratio of 13061:1. With the implant in place, the limb is periodically lengthened by placing the limb into the external drive unit.

By passing electric current into an electric coil, the drive unit produces a rotating magnetic field at 3000rpm. This rotation is captured by the magnet within the implant and is passed through the gearbox to extend the implant. The implant will grow at 1mm every 4 minutes, thereby slowly stretching the soft tissues.

Advantages of the non invasive JTS implant:
  • Minimising surgical intervention minimises risk of infection
  • Very precise lengthening
  • No need for an inpatient stay in hospital
  • No patient anaesthetic or sedation is required
  • Reversibility; if required the implant length can be easily reduced
Indications
  • Malignant tumours arising in bone
  • Patients with significant leg length discrepancies who had previously undergone limb sparing surgery