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The mechanisms of medial pedicle wall violation: insertion method is as important as correct cannulation of the pedicle.

Isik C, Kose KC, Inanmaz ME, Tagil SM, Sarman H - Adv Orthop (2014)

Bottom Line: Medial wall fracture (P = 0.002) and canal penetration were more in group 15P than group 15 (P = 0.001).Groups 10P and 15P were similar regarding medial wall fractures but canal penetration was significantly higher in group 15P (P = 0.001).Medial wall breaches can happen after correct cannulation of pedicles.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopedics and Traumatology, Abant Izzet Baysal University Medical School, Golkoy, 14280 Bolu, Turkey.

ABSTRACT
A cadaver study aims to determine the mechanisms of medial pedicle wall violation after a correct cannulation of the pedicle. The study presents finding out the effect of insertion angle and insertion force on medial wall violation. We used 100 lumbar pedicles of cadavers. Special wooden blocks were produced to simulate a fixed angle fault after a correct pedicle cannulation. Pedicles were divided into 4 groups: 10-degree free drive (group 10), 15-degree free drive (group 15), 10-degree push drive (group 10P), and 15-degree push drive (group 15P). After insertion of pedicle screws, laminectomies were done and the pedicles were evaluated from the inside. Pedicle complications were more in group 10P than group 10 (P = 0.009). Medial wall fracture (P = 0.002) and canal penetration were more in group 15P than group 15 (P = 0.001). Groups 10P and 15P were similar regarding medial wall fractures but canal penetration was significantly higher in group 15P (P = 0.001). Medial wall breaches can happen after correct cannulation of pedicles. Change in insertion angle is one factor but the most important factor is the use of a pushing force while inserting a screw. The pedicle seems to be extremely tolerant to insertion angulation mistakes up to 10 degrees and tends to lead the screw into the correct path spontaneously.

No MeSH data available.


Related in: MedlinePlus

After removal of the primary wires which were in the correct pedicular trajectory. The 10-degree wires are on the right and the 15-degree wires are on the left.
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fig2: After removal of the primary wires which were in the correct pedicular trajectory. The 10-degree wires are on the right and the 15-degree wires are on the left.

Mentions: The cadavers were prepared in a standard fashion in prone position. The lumbar spines of the cadavers were exposed through a midline incision. Using the classical landmarks the left and right pedicles of the cadavers were cannulated with a 3 mm pedicle probe. Then a ball tipped probe was used to check the pedicle pathway. All cannulations were done by an experienced spine surgeon and two other surgeons checked each hole. When the walls were found to be intact, a 3 mm K wire was put into the pedicle representing the correct pedicle pathway. Then the wooden block was slid over the wire through the “0” degree hole. The block was positioned parallel to the spinous processes and then a second K wire was introduced using a power drill through the 10- or 15-degree holes (10 degrees on the right and 15 degrees on the left) (Figure 1). They were implanted 3-4 cm deep. After these first the “0”-degree wire and then the block were removed. Now we had a correctly cannulated pedicle and a K wire representing 10- or 15-degree medial deviation from its axis (Figure 2).


The mechanisms of medial pedicle wall violation: insertion method is as important as correct cannulation of the pedicle.

Isik C, Kose KC, Inanmaz ME, Tagil SM, Sarman H - Adv Orthop (2014)

After removal of the primary wires which were in the correct pedicular trajectory. The 10-degree wires are on the right and the 15-degree wires are on the left.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4221974&req=5

fig2: After removal of the primary wires which were in the correct pedicular trajectory. The 10-degree wires are on the right and the 15-degree wires are on the left.
Mentions: The cadavers were prepared in a standard fashion in prone position. The lumbar spines of the cadavers were exposed through a midline incision. Using the classical landmarks the left and right pedicles of the cadavers were cannulated with a 3 mm pedicle probe. Then a ball tipped probe was used to check the pedicle pathway. All cannulations were done by an experienced spine surgeon and two other surgeons checked each hole. When the walls were found to be intact, a 3 mm K wire was put into the pedicle representing the correct pedicle pathway. Then the wooden block was slid over the wire through the “0” degree hole. The block was positioned parallel to the spinous processes and then a second K wire was introduced using a power drill through the 10- or 15-degree holes (10 degrees on the right and 15 degrees on the left) (Figure 1). They were implanted 3-4 cm deep. After these first the “0”-degree wire and then the block were removed. Now we had a correctly cannulated pedicle and a K wire representing 10- or 15-degree medial deviation from its axis (Figure 2).

Bottom Line: Medial wall fracture (P = 0.002) and canal penetration were more in group 15P than group 15 (P = 0.001).Groups 10P and 15P were similar regarding medial wall fractures but canal penetration was significantly higher in group 15P (P = 0.001).Medial wall breaches can happen after correct cannulation of pedicles.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopedics and Traumatology, Abant Izzet Baysal University Medical School, Golkoy, 14280 Bolu, Turkey.

ABSTRACT
A cadaver study aims to determine the mechanisms of medial pedicle wall violation after a correct cannulation of the pedicle. The study presents finding out the effect of insertion angle and insertion force on medial wall violation. We used 100 lumbar pedicles of cadavers. Special wooden blocks were produced to simulate a fixed angle fault after a correct pedicle cannulation. Pedicles were divided into 4 groups: 10-degree free drive (group 10), 15-degree free drive (group 15), 10-degree push drive (group 10P), and 15-degree push drive (group 15P). After insertion of pedicle screws, laminectomies were done and the pedicles were evaluated from the inside. Pedicle complications were more in group 10P than group 10 (P = 0.009). Medial wall fracture (P = 0.002) and canal penetration were more in group 15P than group 15 (P = 0.001). Groups 10P and 15P were similar regarding medial wall fractures but canal penetration was significantly higher in group 15P (P = 0.001). Medial wall breaches can happen after correct cannulation of pedicles. Change in insertion angle is one factor but the most important factor is the use of a pushing force while inserting a screw. The pedicle seems to be extremely tolerant to insertion angulation mistakes up to 10 degrees and tends to lead the screw into the correct path spontaneously.

No MeSH data available.


Related in: MedlinePlus