Biomedical subjects

Debi Mukherjee

Publications and source records attributed to Debi Mukherjee.

6 recordsLinked to original sources

PubMed2006

Augmentation of anterior lumbar interbody fusion with anterior pedicle screw fixation: demonstration of novel constructs and evaluation of biomechanical stability in cadaveric specimens.

OBJECTIVE: Anterior lumbar interbody fusion (ALIF) has proven effective for indications including discogenic back pain, nonunion, and instability. Current practice involves posterior pedicle screw augmentation of the ALIF procedure (ALIF-PPS). This approach requires intraoperative repositioning of the patient for percutaneous posterior pedicle screw placement. We have developed a novel technique in which the ALIF procedure is augmented with anterior pedicle screws (APS; ALIF-APS). In this study, we introduce this new technique and compare the biomechanical stability of the novel ALIF-APS with the current standard ALIF-PPS. METHODS: The technique was demonstrated in a cadaveric L4-S1 specimen using neuronavigation and fluoroscopy. Plain radiographs and computed tomographic scans of the construct were obtained. Twelve cadaveric spines (7 men and 5 women) from donors with an average age of 81 years (range, 64-93 yr) were then harvested from L4-S1. Six specimens were dedicated to ALIF-APS constructs, and the remaining six were dedicated to ALIF-PPS constructs. The specimens were then studied at L5-S1 in the following steps: 1) intact form, 2) after anterior discectomy, 3) after implantation of titanium cages (ALIF), and 4) after APS or PPS fixation in conjunction with the ALIF. Measurements were obtained in axial rotation and left and right lateral bending flexion-extension. Data were normalized by calculating the ratio of the stiffness of the instrumented to the intact spine. Statistical analyses were then performed on the data. RESULTS: Radiographs and computed tomographic scans of the construct showed accurate placement of the APS at L5 and S1. The normalized data showed that ALIF-APS and ALIF-PPS had approximately equal stability in axial rotation (1.17 +/- 0.43 versus 0.85 +/- 0.14), lateral bending (0.93 +/- 0.22 versus 0.95 +/- 0.16), and flexion- extension (0.77 +/- 0.13 versus 0.84 +/- 0.2). Paired t test analysis did not show a significant difference between the biomechanical stiffness of ALIF-APS and ALIF-PPS in axial rotation, lateral bending, and flexion-extension. CONCLUSION: We demonstrate a new technique in a cadaveric specimen whereby the ALIF procedure is augmented with APS fixation using neuronavigation and fluoroscopy. Biomechanical evaluation of the constructs suggests that the ALIF-APS has comparable stability with ALIF-PPS. APS augmentation of ALIF has potential advantages over the current standard ALIF-PPS because it can 1) eliminate the patient repositioning step, 2) minimize the total number of incisions and the total operative time, and 3) protect against dislocation of the ALIF interbody graft or cage. Work is in progress to develop a low-profile system for the novel APS constructs described here.

Aged↗

PubMed2006

Accuracy of pedicle screw placement for lumbar fusion using anatomic landmarks versus open laminectomy: a comparison of two surgical techniques in cadaveric specimens.

OBJECTIVE: We determined whether the accuracy of lumbar pedicle screw placement is optimized by performing a laminectomy before screw placement with screw entry point and trajectory being guided by pedicle visualization and palpation (Technique 1). This technique was compared with a technique using anatomic landmarks for pedicle screw placement (Technique 2). The biomechanical stability of the instrumented constructs, in the absence and presence of a laminectomy, was also compared. METHODS: Twelve L1-L3 specimens were harvested from fresh cadavers. The intact laminectomy and instrumented spines were biomechanically tested in flexion and extension, lateral bending, and axial rotation. Laminectomies were performed in six of the 12 specimens before pedicle screw placement using Technique 1. The remaining six specimens underwent pedicle screw and rod fixation using Technique 2. Computed tomographic images were obtained for all instrumented specimens. Deviation of the screws from the ideal entry point or trajectory was analyzed to quantitatively compare the two techniques. RESULTS: Computed tomographic analysis of the specimens showed that all screw placements were within the pedicles. Scatter plot analysis demonstrated that screws placed using Technique 2 were more likely to have the combination of entry points and trajectories medial to the ideal entry point and trajectory. Laminectomy did not weaken the final pedicle screw and rod-fixated constructs. CONCLUSION: All screw placements were grossly within the confines of the pedicles, regardless of technique, as evidenced by computed tomographic analysis. Furthermore, the anatomic landmark technique and the open laminectomy technique yielded biomechanically equivalent pedicle screw and rod-fixated constructs.

Aged↗

PubMed2005

Tying a loop-to-strand suture: is it safe?

OBJECTIVE: This study was undertaken to evaluate the integrity of the loop-to-strand knot when tied with square and nonidentical sliding knots. STUDY DESIGN: The synthetic absorbable monofilament suture poliglecaprone 25 in 0 and 2-0 suture gauges was used in this experiment. For each suture gauge, 3 groups of knots were tested: (1) single strand-to-single strand, flat square knot, (2) loop-to-single strand, flat square knot, and (3) loop-to-single strand, nonidentical sliding knot. All knots were tied with 6 throws. The proportion of knots becoming untied was compared among the 3 groups for each suture gauge. Ultimate load required to untie or break knots within each group was also evaluated. RESULTS: The loop-to-strand knot performed well in both suture gauges tested as long as it was tied with a flat square knot. The loop-to-strand knot tied with a nonidentical sliding knot had an unacceptably high failure rate. CONCLUSION: The loop-to-strand termination of a continuous suture may be acceptable when tied with a 6-throw flat square knot but not acceptable if tied with sliding knots.

Catgut↗

PubMed2004

The effect of number of throws on knot security with nonidentical sliding knots.

OBJECTIVE: The study was undertaken to test the integrity of nonidentical sliding knots made with 3 throws compared with those made with 6 throws with monofilament and braided absorbable suture. STUDY DESIGN: The 3 throw nonidentical sliding knot was compared with the 6 throw nonidentical sliding knot in 4 different suture groups. The groups were 0-0 polydioxanone, 2-0 polydioxanone, 0-0 polyglactin 910, and 2-0 polyglactin 910. Knots were tested to failure with a tensiometer. The proportion of 3 throw knots becoming untied was compared with the 6 throw knot within each group. Ultimate load required to break tied knots within each suture group was also evaluated. RESULTS: The 3 throw knots had very high rates of knot failure and untied significantly more often than the 6 throw knots. CONCLUSION: The 6 throw nonidentical sliding knot demonstrates superior knot integrity compared with the 3 throw knot with both monofilament and braided absorbable suture.

Female↗

PubMed2004

Knot integrity with nonidentical and parallel sliding knots.

OBJECTIVE: The study was performed to test the knot integrity of parallel and nonidentical sliding knots with the use of monofilament suture. STUDY DESIGN: We investigated the proportion of parallel sliding knots that become untied compared with nonidentical sliding knots in four different monofilament suture configurations: group A, 6 throws, 0-0 gauge; group B, 10 throws, 0-0 gauge; group C, 6 throws, 2-0 gauge; group D, 10 throws, 2-0 gauge. Each combination was tested 20 times, for a total of 160 knots. RESULTS: The nonidentical sliding knot untied 40% of the time in group A compared with 0% for the parallel knot (P=.003). In the other 6-throw group, group C, 45% of the nonidentical knots became untied compared with 0% of the parallel knots (P=.001). There were no significant differences in the proportions of untying for each knot type in the 10-throw groups. CONCLUSION: Parallel sliding knots demonstrate superior knot integrity compared with nonidentical sliding knots with monofilament suture. The addition of throws to the nonidentical knot improves its knot security.

Humans↗

PubMed2002

Mechanical performance of knots using braided and monofilament absorbable sutures.

OBJECTIVE: The study was undertaken to test the integrity of various flat and sliding knots with the use of braided and monofilament absorbable sutures. STUDY DESIGN: There were four study groups, each of which consisted of a single suture type and size, with five different knots. Each combination was tested 10 times for a total of 200 experiments. The suture types used were 0-0 and 2-0 Glycomer 631 (Biosyn) and 0-0 and 2-0 coated Lactomer (Polysorb). Knots tested were the square knots, surgeon's knots, modified granny flat knots, and modified identical and nonidentical sliding knots. Knots were tested to failure with a tensiometer. We compared the proportion of knots becoming untied within each group and the ultimate load required to break tied knots. RESULTS: In the 0-0 and 2-0 Lactomer groups, 90% and 60% of modified identical sliding knots, respectively, became untied, significantly more than all other knots. CONCLUSION: When 0-0 and 2-0 Lactomer sutures were used, modified identical sliding knots should be avoided.

Absorption↗