Comparison of insufflation vs. retractional technique for laparoscopic-assisted intervertebral fusion of the lumbar spine.

Laparoscopic transperitoneal fusion of the L5-S1 spinal interspace has become a common procedure. Retroperitoneal retraction and laparoscopic instrumentation without insufflation also allows visualization of the upper lumbar spaces, but this procedure is much more difficult to accomplish. We review and compare our results using each of these techniques for the treatment of mechanical instability and chronic back pain. A total of 35 selected patients underwent intervertebral fusion between February 1996 and August 1998. Their mean age was 48 years. There were 22 female and 13 male patients. Standard CO2 insufflation was used in 10 patients with L5-S1 fusions. Retractional gasless technique was used in nine patients with fusions at L5-S1, 16 patients at L4-L5, one patient at L3-L4, three patients at L2-3, and one patient at L1-L2. Thus, we performed a total of 40 lumbar fusions in 35 patients. In the 19 patients with the gasless technique, a balloon dissector and retractor facilitated the retroperitoneal exposure. Seven of these 19 patients were converted to open procedures, most commonly due to lacerations of the peritoneal lining that prohibited visualization. None of the L5-S1 patients with insufflation were converted to open. Mean operative time in the insufflated patients was 152 min vs. 181 min for the retractional technique. There were seven complications in the transperitoneal group: one fusion device migration, one postoperative UTI, one intracerebral hemorrhage, one severe postoperative pancreatitis, and three iliac vein lacerations. There were 16 complications in the retroperitoneal group: one deep vein thromboses, one serosal bowel injury, one small tear in the spleen, one cage migration, one postoperative pulmonary atelectasis, one postoperative hydrocele, four postoperative ileus, and six peritoneal tears. The mean postoperative stay was three days for both groups. There were no deaths. The L5-S1 interspace is best approached transperitoneally for anterior fusion. Although the retroperitoneal retractional technique is much more difficult and has a longer and steeper learning curve, it does allow laparoscopic anterior fusion of the upper lumbar spine.

Comparison of insufflation vs retractional technique for laparoscopic-assisted intervertebral fusion of the lumbar spine.

Laparoscopic transperitoneal fusion of the L5-S1 spinal interspace has become a common procedure. Retroperitoneal retraction and laparoscopic instrumentation without insufflation also allows visualization of the upper lumbar spaces, but this procedure is much more difficult to accomplish. We review and compare our results using each of these techniques for the treatment of mechanical instability and chronic back pain. A total of 35 selected patients underwent intervertebral fusion between February 1996 and August 1998. Their mean age was 48 years. There were 22 female and 13 male patients. Standard CO2 insufflation was used in 10 patients with L5-S1 fusions. Retractional gasless technique was used in nine patients with fusions at L5-S1, 16 patients at L4-L5, one patient at L3-L4, three patients at L2-3, and one patient at L1-L2. Thus, we performed a total of 40 lumbar fusions in 35 patients. In the 19 patients with the gasless technique, a balloon dissector and retractor facilitated the retroperitoneal exposure. Seven of these 19 patients were converted to open procedures, most commonly due to lacerations of the peritoneal lining that prohibited visualization. None of the L5-S1 patients with insufflation were converted to open. Mean operative time in the insufflated patients was 152 min vs 181 min for the retractional technique. There were seven complications in the transperitoneal group: one fusion device migration, one postoperative UTI, one intracerebral hemorrhage, one severe postoperative pancreatitis, and three iliac vein lacerations. There were 16 complications in the retroperitoneal group: one deep vein thromboses, one serosal bowel injury, one small tear in the spleen, one cage migration, one postoperative pulmonary atelectasis, one postoperative hydrocele, four postoperative ileus, and six peritoneal tears. The mean postoperative stay was three days for both groups. There were no deaths. The L5-S1 interspace is best approached transperitoneally for anterior fusion. Although the retroperitoneal retractional technique is much more difficult and has a longer and steeper learning curve, it does allow laparoscopic anterior fusion of the upper lumbar spine.

Comparative pull-out strength of tapped and untapped pilot holes for bicortical anterior cervical screws.

STUDY DESIGN: This biomechanical study analyzed the axial pull-out strength of tapped versus untapped pilot holes for bicortical screws in the anterior cervical spine. OBJECTIVE: To determine which pilot hole preparation method was mechanically better. SUMMARY OF BACKGROUND DATA: Tapping pilot holes in the lumbar spine was previously shown significantly to reduce pull-out strength of pedicle screws. No study was found investigating the effect of tapping on pilot holes for anterior cervical bicortical screws. METHODS: Twenty-five unembalmed human cadaveric cervical vertebrae (C3-C7) were tested. Two identical pilot holes were drilled into each vertebra: one pilot hole was tapped, and the control pilot hole was not tapped. A fully threaded cortical bone screw was inserted into each pilot hole. Screw pull-out strength was determined using a servocontrolled hydraulic materials testing system and an axial load cell. Force-deformation and failure curves were obtained. RESULTS: There were no statistically significant differences between the axial pull-out strength of tapped and untapped pilot holes at any vertebral level. Mean force to-failure was 386 +/- 42 N in the untapped pilot holes and 397 +/- 48 N in the tapped pilot holes. CONCLUSIONS: Tapping a pilot hole for bicortical screws of the anterior cervical spine neither weakens nor strengthens the axial pull-out strength of fully threaded cortical bone screws. Tapping may be unnecessary; however, it may be desirable in patients with dense bone to cut the thread profile into the bone or if the screws have dull tips and threads.

Cranioplasty using gentamicin-loaded acrylic cement: a test of neurotoxicity.

Cranioplasty represents a formidable challenge for neuro-surgeons, with a significant morbidity from both early and late wound infections. Polymethylmethacrylate (PMMA) is one of the most widely used materials in this setting. Despite the advantages of this material, such as ease of handling and inert biochemical properties, it is still a foreign body that is prone to infection. We present an animal model using a gentamicin-impregnated PMMA patch to assess the neurotoxicity as well as the efficacy of using this as an alternative material to lessen the infectious morbidity in this clinical setting. In part two of our experiment, we used a PMMA patch of similar weight and surface area in a physiological saline solution to determine the rate of gentamicin elution from the patch. The results obtained appear promising with no evidence of neurotoxicity and warrant further study to assess the clinical efficacy of PMMA in this setting.