Projects / Programmes source: ARIS

Piezoresistive Force Sensors for controlled spinal nerve root retraction in lumbar disc surgery – a new surgical instrument for prevention of intraoperative root traction injury

Research activity

Code Science Field Subfield
3.03.00  Medical sciences  Neurobiology   

Code Science Field
B640  Biomedical sciences  Neurology, neuropsychology, neurophysiology 
Piezoresistor, MEMS (micro-electro-mechanical system), retractor, traction injury, spinal nerve root, lumbar herniated disc, prevention
Evaluation (rules)
source: COBISS
Researchers (12)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  11682  MSc Uroš Aljančič  Electronic components and technologies  Researcher  2008 - 2011  206 
2.  01926  PhD Slavko Amon  Electronic components and technologies  Researcher  2008 - 2011  473 
3.  24578  PhD Saba Battelino  Neurobiology  Researcher  2008 - 2011  587 
4.  25617  PhD Mitja Benedičič  Neurobiology  Junior researcher  2008 - 2011  105 
5.  10511  PhD Roman Bošnjak  Neurobiology  Head  2008 - 2011  414 
6.  17125  Matjaž Cvar    Technical associate  2008 - 2011 
7.  17691  Romana Kren    Technical associate  2008 - 2011 
8.  29611  PhD Matej Makovec  Medical sciences  Researcher  2008 - 2009  73 
9.  20186  PhD Matej Možek  Electronic components and technologies  Researcher  2008 - 2011  270 
10.  28467  PhD Samo Penič  Electronic components and technologies  Researcher  2008 - 2009  115 
11.  05075  PhD Drago Resnik  Electronic components and technologies  Researcher  2008 - 2011  261 
12.  04383  PhD Danilo Vrtačnik  Electronic components and technologies  Researcher  2008 - 2011  309 
Organisations (2)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0312  University Medical Centre Ljubljana  Ljubljana  5057272000  76,699 
2.  1538  University of Ljubljana, Faculty of Electrical Engineering  Ljubljana  1626965  27,611 
Surgical manipulation of the spinal nerve root is an unavoidable part of posterior lumbar discectomy. The excessive magnitude and duration of retraction may result in permanent nerve root injury from ischemia and nerve root deformation. The incidence of battered root syndrome may be decreased by gentle intermittent retraction and with shorter total retraction time. However, the immediate effects of mechanical load to the root can not be controlled in on-line manner without continuous intraoperative electrophysiological monitoring and force x time measurement. Hofmann or H reflex is the result of submaximal, orthodromic stimulation of I-A sensory fibers in the posterior tibial nerve at the popliteal fossa and is clinically associated with S1 nerve root injury. It has not yet been used intraoperatively as a tool for monitoring ongoing conduction abnormalities related to compression and stretching of the S1 spinal nerve root during posterior discectomy. A piezoresistive retractor will be developed and clinically tested. For this purpose, the H waves were continuously detected from soleus muscle in patients with mild S1 radiculopathy who underwent posterior discectomy. In addition, spinal nerve root potentials (SRP) were detected concomitantly directly from the spinal nerve root above and below the compression site. Both methods (electrophysiological monitoring and force measurement ) will determine safe range of traction in posterior lumbar discectomy. Piezoresistive retractor will modify current operative technique and improve postoperative results.
Significance for science
Prototype of piezoresistive retractor enabled monitoring of mechanical load (F, t) to the nerve root during intermittent root retraction and establishing criteria for critical mechanical load, which were unknown. This was first realization of combined measurement of applied mechanical manipulative energy to the root and conduction function of the root. The electrophysiological parametres (such as amplitude decrement, loss of signal, increased signal polyphasy = desynchronisation) correlated well to increased mechanical load. Average root force during surgery was 81,4-224,8 g and correlated to outcome satisfaction. Usage of piezoresistive equipped instruments proven here opens a new research field in other surgical fields and robotics where vitality and integrity of tissue should be primarily preserved during controled surgical manipulation.
Significance for the country
The idea and realisation of two dimensional (2D) nerve root retractor is original Slovenia contribution to improve results in one of the most general spine surgeries. Piezoresistive retractor will present a recognizible and original result of cooperation of slovenian technical and medicine aplicative science for health improvement.
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