Mark Potocnjak - Academia.edu (original) (raw)

Papers by Mark Potocnjak

Research paper thumbnail of Brachial plexus gunshot injury in an infant

Child's Nervous System, 2000

Research paper thumbnail of Hook—rod with pedicle screw fixation for unstable spinal fracture

Journal of Neurosurgery: Spine, 2000

U A technique is described in which spinal fracture repositioning, decompression, and stabilizati... more U A technique is described in which spinal fracture repositioning, decompression, and stabilization are achieved by a combination of hook—rod and pedicle screw fixation. This straightforward technique is useful for performing acute decompression in patients with partial neurological deficits and multisystem injuries. A laminectomy allows for placement of a stiffer fixation system, and it improves the insufficient canal clearance obtained when performing annulotaxis alone.

Research paper thumbnail of The anatomy of the Berrettini branch: implications for carpal tunnel release

Journal of Neurosurgery, 1999

Object. Dissections were performed in 100 fresh cadaver palms to determine the frequency with whi... more Object. Dissections were performed in 100 fresh cadaver palms to determine the frequency with which superficial palmar communication between the median and ulnar nerves occurs and to what extent it might incur iatrogenic injury during endoscopic carpal tunnel release.Methods. Superficial palmar communication between the median and ulnar nerves was present in 81% of the dissected hands. Superficial palmar communication, also known as the Berrettini branch, has been classified into four distinct types by Ferrari and Gilbert. Twelve hands were classified as Group 1 (communication in an oblique course from the ulnar to the median nerve originating > 4 mm above the distal margin of the transverse carpal ligament [TCL]), 16 hands were classified as Group 2 (communication parallel to the distal margin of the TCL), and 53 hands were classified as Group 3 (communication in an oblique course from the ulnar nerve to the third common digital nerve, originating below the distal margin of the ...

Research paper thumbnail of The value of an operating microscope in peripheral nerve repair

International Orthopaedics, 1998

The aim of this study was to test the hypothesis that the use of an operating microscope improves... more The aim of this study was to test the hypothesis that the use of an operating microscope improves the results of peripheral nerve repair. Tibial nerve grafting was carried out on 48 Fischer rats divided into 2 groups: in one, a loupe was used, and in the other a surgical microscope. At 5 months after grafting, recovery was evaluated by functional, electromyographic, and morphometric tests. The mean motor nerve conduction velocity was 26.77+9.37 m/sec in the group where the loupe was used compared with 44.19+11.36 m/s when the microscope group was used. The soleus muscle weight and the diameter of myelinated fibres also confirmed better regeneration in the microscope group. These results clearly indicate that it is essential to use the microscope for peripheral nerve repair. Résumé. Le but de l'étude est de faire tester l'hypothèse que l'aide du microscope améliore les résultats de la chirurgie du nerf périphérique. La greffe du nerf tibial a été pratiquée sur 48 rats Fischer, repartis en deux groupes, l'un avec l'aide de la loupe et l'autre avec l'aide du microscope. Cinq mois après la greffe les résultats ont été soumis à une évaluation fonctionnelle, électromyographique et morphométrique. Les moyennes de la vitesse de la transmission motrice du nerf dans le groupe assisté par la loupe et celui assisté par le microscope étaient 26.77+9.37 m/s et 44.19+11.36 m/s respectivement. L'équivalent du test clinique, le poids du muscle soleus ainsi que les mésures du diamètre des fibres myelinisées ont aussi démontré une meilleure régénération, dans le groupe assisté par microscope. Ces resultats montrent clairement que l'aide du microscope est essentielle pour la réfection du nerf périphérique.

Research paper thumbnail of Evaluation of Functional Nerve Recovery Shows that Allogeneic Nerve Graft Treated with ICAM-1 and LFA-1 mAbs can be Good Alternative to Syngeneic Graft

Acta Neurochirurgica, 1999

The objective of the study is to establish recovery results of tibial nerve defects reconstructed... more The objective of the study is to establish recovery results of tibial nerve defects reconstructed using allogeneic and xenogeneic graft, in host immunosuppressed with Intercellular Adhesion Molecule-1 (ICAM-1) and Lymphocyte Function Antigen-1 (LFA-1) monoclonal antibodies (mAbs). A pilot study was conducted in fifteen Fischer rats by forming a 1 cm right tibial nerve gap, then reconstructing it with 1.2 cm long grafts, namely, Wistar allogeneic, Black mouse xenogeneic, and syngeneic (n = 5/group). The main study included forty-eight rats allocated to the following groups (n = 12/group): 1) Allograft without treatment as control group. 2) Allograft with intraperitoneal ICAM-1 and LFA-1 mAbs treatment. 3) Allograft preserved in Belzers' solution including ICAM-1 mAbs plus standard intraperitoneal treatment. 4) Syngraft as benchmark. At 3, 6 and 9 weeks postengraftment walking track analysis was performed and expressed as Tibial Functional Index (TFI). Motor and compound nerve action potential across the graft conduction velocities were measured at week 10. Xenograft did not show any functional recovery and was therefore excluded from main study. However, pilot and main study results showed recovery results in both treated allogeneic groups and were comparable to benchmark syngraft. Therefore, allogeneic nerve graft could be an alternative in peripheral nerve reconstruction and spinal cord grafting.

Research paper thumbnail of Pullout resistance of thoracic extrapedicular screws used as a salvage procedure

The spine journal : official journal of the North American Spine Society

Extrapedicular screws are placed more laterally than intrapedicular screws and pass through the t... more Extrapedicular screws are placed more laterally than intrapedicular screws and pass through the transverse process or rib head before entering the vertebral body. These screws are sometimes placed to salvage failed pedicle screws, but the change in pullout resistance of extrapedicular screws after salvage has not been quantified. To quantify the pullout resistance of thoracic extrapedicular screws compared with intrapedicular screws and the pullout resistance of newly inserted screws compared with extrapedicular screws used as salvage for failed intrapedicular screws. In vitro paired comparison of screw pullout resistance in isolated thoracic vertebrae. Tapered monoaxial pedicle screws were inserted in the left or right pedicle of 11 human cadaveric thoracic vertebrae. An extrapedicular screw was inserted on the contralateral side. Both screws were pulled out axially at 0.5 mm/s using a servohydraulic test frame while applied load was recorded. Then a fresh extrapedicular screw was ...

Research paper thumbnail of Brachial plexus gunshot injury in an infant

Child's Nervous System, 2000

Research paper thumbnail of Hook—rod with pedicle screw fixation for unstable spinal fracture

Journal of Neurosurgery: Spine, 2000

U A technique is described in which spinal fracture repositioning, decompression, and stabilizati... more U A technique is described in which spinal fracture repositioning, decompression, and stabilization are achieved by a combination of hook—rod and pedicle screw fixation. This straightforward technique is useful for performing acute decompression in patients with partial neurological deficits and multisystem injuries. A laminectomy allows for placement of a stiffer fixation system, and it improves the insufficient canal clearance obtained when performing annulotaxis alone.

Research paper thumbnail of The anatomy of the Berrettini branch: implications for carpal tunnel release

Journal of Neurosurgery, 1999

Object. Dissections were performed in 100 fresh cadaver palms to determine the frequency with whi... more Object. Dissections were performed in 100 fresh cadaver palms to determine the frequency with which superficial palmar communication between the median and ulnar nerves occurs and to what extent it might incur iatrogenic injury during endoscopic carpal tunnel release.Methods. Superficial palmar communication between the median and ulnar nerves was present in 81% of the dissected hands. Superficial palmar communication, also known as the Berrettini branch, has been classified into four distinct types by Ferrari and Gilbert. Twelve hands were classified as Group 1 (communication in an oblique course from the ulnar to the median nerve originating > 4 mm above the distal margin of the transverse carpal ligament [TCL]), 16 hands were classified as Group 2 (communication parallel to the distal margin of the TCL), and 53 hands were classified as Group 3 (communication in an oblique course from the ulnar nerve to the third common digital nerve, originating below the distal margin of the ...

Research paper thumbnail of The value of an operating microscope in peripheral nerve repair

International Orthopaedics, 1998

The aim of this study was to test the hypothesis that the use of an operating microscope improves... more The aim of this study was to test the hypothesis that the use of an operating microscope improves the results of peripheral nerve repair. Tibial nerve grafting was carried out on 48 Fischer rats divided into 2 groups: in one, a loupe was used, and in the other a surgical microscope. At 5 months after grafting, recovery was evaluated by functional, electromyographic, and morphometric tests. The mean motor nerve conduction velocity was 26.77+9.37 m/sec in the group where the loupe was used compared with 44.19+11.36 m/s when the microscope group was used. The soleus muscle weight and the diameter of myelinated fibres also confirmed better regeneration in the microscope group. These results clearly indicate that it is essential to use the microscope for peripheral nerve repair. Résumé. Le but de l'étude est de faire tester l'hypothèse que l'aide du microscope améliore les résultats de la chirurgie du nerf périphérique. La greffe du nerf tibial a été pratiquée sur 48 rats Fischer, repartis en deux groupes, l'un avec l'aide de la loupe et l'autre avec l'aide du microscope. Cinq mois après la greffe les résultats ont été soumis à une évaluation fonctionnelle, électromyographique et morphométrique. Les moyennes de la vitesse de la transmission motrice du nerf dans le groupe assisté par la loupe et celui assisté par le microscope étaient 26.77+9.37 m/s et 44.19+11.36 m/s respectivement. L'équivalent du test clinique, le poids du muscle soleus ainsi que les mésures du diamètre des fibres myelinisées ont aussi démontré une meilleure régénération, dans le groupe assisté par microscope. Ces resultats montrent clairement que l'aide du microscope est essentielle pour la réfection du nerf périphérique.

Research paper thumbnail of Evaluation of Functional Nerve Recovery Shows that Allogeneic Nerve Graft Treated with ICAM-1 and LFA-1 mAbs can be Good Alternative to Syngeneic Graft

Acta Neurochirurgica, 1999

The objective of the study is to establish recovery results of tibial nerve defects reconstructed... more The objective of the study is to establish recovery results of tibial nerve defects reconstructed using allogeneic and xenogeneic graft, in host immunosuppressed with Intercellular Adhesion Molecule-1 (ICAM-1) and Lymphocyte Function Antigen-1 (LFA-1) monoclonal antibodies (mAbs). A pilot study was conducted in fifteen Fischer rats by forming a 1 cm right tibial nerve gap, then reconstructing it with 1.2 cm long grafts, namely, Wistar allogeneic, Black mouse xenogeneic, and syngeneic (n = 5/group). The main study included forty-eight rats allocated to the following groups (n = 12/group): 1) Allograft without treatment as control group. 2) Allograft with intraperitoneal ICAM-1 and LFA-1 mAbs treatment. 3) Allograft preserved in Belzers' solution including ICAM-1 mAbs plus standard intraperitoneal treatment. 4) Syngraft as benchmark. At 3, 6 and 9 weeks postengraftment walking track analysis was performed and expressed as Tibial Functional Index (TFI). Motor and compound nerve action potential across the graft conduction velocities were measured at week 10. Xenograft did not show any functional recovery and was therefore excluded from main study. However, pilot and main study results showed recovery results in both treated allogeneic groups and were comparable to benchmark syngraft. Therefore, allogeneic nerve graft could be an alternative in peripheral nerve reconstruction and spinal cord grafting.

Research paper thumbnail of Pullout resistance of thoracic extrapedicular screws used as a salvage procedure

The spine journal : official journal of the North American Spine Society

Extrapedicular screws are placed more laterally than intrapedicular screws and pass through the t... more Extrapedicular screws are placed more laterally than intrapedicular screws and pass through the transverse process or rib head before entering the vertebral body. These screws are sometimes placed to salvage failed pedicle screws, but the change in pullout resistance of extrapedicular screws after salvage has not been quantified. To quantify the pullout resistance of thoracic extrapedicular screws compared with intrapedicular screws and the pullout resistance of newly inserted screws compared with extrapedicular screws used as salvage for failed intrapedicular screws. In vitro paired comparison of screw pullout resistance in isolated thoracic vertebrae. Tapered monoaxial pedicle screws were inserted in the left or right pedicle of 11 human cadaveric thoracic vertebrae. An extrapedicular screw was inserted on the contralateral side. Both screws were pulled out axially at 0.5 mm/s using a servohydraulic test frame while applied load was recorded. Then a fresh extrapedicular screw was ...