Dilip K Sengupta

Dartmouth–Hitchcock Medical Center, LEB, New Hampshire, United States

Are you Dilip K Sengupta?

Claim your profile

Publications (39)75.41 Total impact

  • Dilip K Sengupta, Haibo Fan
    [Show abstract] [Hide abstract]
    ABSTRACT: Study Design. A biomechanical study in cadaveric lumbar spineObjective. To establish the basis of mechanical stability in degenerative disc disease from the relationship between Range o f Motion (ROM), Neutral Zone motion (NZ), Intra-Discal Pressure Profile (IDPP), and Instantaneous Axis or Rotation (IAR) in advancing grades of disc degeneration.Summary of Background Data. The basis of mechanical instability in lumbar disc degeneration remains poorly understood. Controversy exists between abnormal motion vs. abnormal loading theories.Methods: Thirty-nine lumbar motion segments were graded for staging of disc degeneration with MRI scan. These specimens were tested for ROM, and NZ in a 6 degrees of freedom spine simulator, with 7.5Nm unconstrained, cyclical loading. Continuous tracking of IAR were derived from ROM data. IDPP were determined using needle mounted pressure transducer, drawn across the disc space under constant loading.Results. The ROM showed insignificant change, but a trend of increase from grade I through III and a decrease with advanced degeneration. NZ increased significantly with advancing disc degeneration. IDPP showed an even distribution of the load in normal discs, but a depressurized nucleus, and irregular spikes of excessive loading, with advancing degeneration. The IAR showed a smooth excursion in normal vs. irregular jerky excursion in degenerated discs, without significant change in excursion. The center of rotation (CR), derived from IAR, showed significantly increased vertical translation with advancing degeneration, indicating an abnormal quality-of-motion.Conclusion. The study established a basis of mechanical instability in the lumbar spine with advancing disc degeneration, as an abnormal quality-of-motion represented by variation in IAR and CR, increased NZ motion without any increase in quantity-of-motion, and abnormal load distribution across the disc space with spikes of high load amidst depressurized nucleus. The study can't identify clinical instability, but finds an association between the abnormal motions vs. abnormal load distribution in mechanical instability.
    Spine 02/2014; 39(13). DOI:10.1097/BRS.0000000000000292 · 2.45 Impact Factor
  • Peng Huang, Dilip K Sengupta
    [Show abstract] [Hide abstract]
    ABSTRACT: Study Design. A single-center retrospective study.Objective. To compare the speed of recovery of different sensory symptoms, pain, numbness and paresthesia, after lumbar nerve root decompression.Summary of Background Data. Lumbar radiculopathy is characterized by different sensory symptoms like pain, numbness and paresthesia, which may resolve at different rates following surgical decompression.Methods. 85 cases with predominant lumbar radiculopathy treated surgically were reviewed. Oswestry Disability Index (ODI) score, SF-36 scores [Physical Component Summary (PCS) and Mental Component Summary (MCS)], and pain drawing at pre-operative and at 6 weeks, 3 months, 6 months and 1 year follow-up were reviewed. Recovery rate between different sensory symptoms were compared in all patients, and between short-term compression (STC) (<6mo) vs. long-term compression (LTC) groups.Results. At baseline, 73(85.8%) patients had pain, 63(74.1%) had numbness, and 38(44.7%) had paresthesia; 28(32.9%) had all these three component of sensory symptoms. Mean pain score improved fastest (55.3% at 6 wks); further resolution until 1 yr was slow and not significant compared to each previous visit. Both numbness and paresthesia scores showed a trend of faster recovery during the initial 6 weeks period (20.5% and 24% respectively); paresthesia recovery reached a plateau at 3 month post-op, but numbness continued a slow recovery until 1 yr follow-up. Both ODI score and PCS scores (54.02 +/- 1.87 and 26.29 +/-0.93 respectively at baseline) improved significantly compared to each previous visits at 6 wk and 3 mo post-op, but further improvement was insignificant. MCS showed a similar trend but smaller improvement. STC group had faster recovery of pain compared to LTC group.Conclusions. In lumbar radiculopathy patients following surgical decompression, pain recovers fastest, in the first six weeks post-op, followed by paresthesia recovery which plateaus at 3 months post-op. Numbness recovers at a slower pace but continues until 1 year.
    Spine 01/2014; 39(8). DOI:10.1097/BRS.0000000000000240 · 2.45 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Conventional posterior dynamic stabilization devices demonstrated a tendency towards highly rigid stabilization approximating that of titanium rods in flexion. In extension, they excessively offload the index segment, making the device as the sole load-bearing structure, with concerns of device failure. The goal of this study was to compare the kinematics and intradiscal pressure of monosegmental stabilization utilizing a new device that incorporates both a flexion and extension dampening spacer to that of rigid internal fixation and a conventional posterior dynamic stabilization device. The hypothesis was the new device would minimize the overloading of adjacent levels compared to rigid and conventional devices which can only bend but not stretch. The biomechanics were compared following injury in a human cadaveric lumbosacral spine under simulated physiological loading conditions. The stabilization with the new posterior dynamic stabilization device significantly reduced motion uniformly in all loading directions, but less so than rigid fixation. The evaluation of adjacent level motion and pressure showed some benefit of the new device when compared to rigid fixation. Posterior dynamic stabilization designs which both bend and stretch showed improved kinematic and load-sharing properties when compared to rigid fixation and when indirectly compared to existing conventional devices without a bumper.
    04/2013; 2013:738252. DOI:10.1155/2013/738252
  • Source
    Dilip K Sengupta, Harry N Herkowitz
    [Show abstract] [Hide abstract]
    ABSTRACT: Posterior dynamic stabilization (PDS) indicates motion preservation devices that are aimed for surgical treatment of activity related mechanical low back pain. A large number of such devices have been introduced during the last 2 decades, without biomechanical design rationale, or clinical evidence of efficacy to address back pain. Implant failure is the commonest complication, which has resulted in withdrawal of some of the PDS devices from the market. In this paper the authors presented the current understanding of clinical instability of lumbar motions segment, proposed a classification, and described the clinical experience of the pedicle screw-based posterior dynamic stabilization devices.
    11/2012; 2012:424268. DOI:10.1155/2012/424268
  • Article: Letters.
    Dilip K Sengupta
    Spine 09/2012; 37(20):1790. · 2.45 Impact Factor
  • Dilip Sengupta, James Sanders, Douglas Burton
    The Spine Journal 10/2011; 11(10):S12–S13. DOI:10.1016/j.spinee.2011.08.040 · 2.80 Impact Factor
  • The Spine Journal 10/2011; 11(10):S75-S76. DOI:10.1016/j.spinee.2011.08.189 · 2.80 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The instant axis of rotation (IAR) is an important kinematic property to characterise of lumbar spine motion. The goal of this biomechanical study on cadaver lumbar spine was to determine the excursion of the IAR for flexion (FE), lateral bending (LB) and axial rotation (AR) motion at L4-5 segment. Ten cadaver lumbar spine specimens were tested in a 6 degrees-of-freedom spine tester with continuous clyclical loading using pure moment and follower pre-load, to produce physiological motion. The specimens were x-rayed and CT scanned prior to testing to identify marker position. Continuous motion tracking was done by Optotrak motion capture device. A continuous tracking of the IAR excursion was calculated from the continuous motions capturedata using a computer programme. IAR translates forward in flexion and backwards in extension with mean excursion of 26.5 mm (+/- 5.6 SD). During LB motion, IAR translates laterally in the same direction, and the mean excursion was 15.35 mm (+/- 8.75 SD). During axial rotation the IAR translates in the horizontal plane in a semicircular arc, around the centre of the vertebral body, but the IAR translates in the opposite direction of rotation. The IAR excursion was faster and larger during neutral zone motion in FE and LB, but uniform for AR motion. This is the first published data on the continuous excursion of IAR of a lumbar motion segment. The methodology is accurate and precise, but not practicable for in vivo testing.
    Journal of the Indian Medical Association 06/2011; 109(6):389-90, 392-3, 395.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: As-treated analysis of the Spine Patient Outcomes Research Trial. To compare baseline characteristics and surgical and nonoperative outcomes in degenerative spondylolisthesis (DS) and spinal stenosis (SpS) patients stratified by predominant pain location (i.e., leg vs. back). Evidence suggests that DS and SpS patients with predominant leg pain may have better surgical outcomes than patients with predominant low back pain (LBP). The DS cohort included 591 patients (62% underwent surgery), and the SpS cohort included 615 patients (62% underwent surgery). Patients were classified as leg pain predominant, LBP predominant, or having equal pain according to baseline pain scores. Baseline characteristics were compared between the 3 predominant pain location groups within each diagnostic category, and changes in surgical and nonoperative outcome scores were compared for 2 years. Longitudinal regression models including baseline covariates were used to control for confounders. Among DS patients at baseline, 34% had predominant leg pain, 26% had predominant LBP, and 40% had equal pain. Similarly, 32% of SpS patients had predominant leg pain, 26% had predominant LBP, and 42% had equal pain. DS and SpS patients with predominant leg pain had baseline scores indicative of less severe symptoms. Leg pain predominant DS and SpS patients treated surgically improved significantly more than LBP predominant patients on all primary outcome measures at 1 and 2 years. Surgical outcomes for the equal pain groups were intermediate to those of the predominant leg pain and LBP groups. The differences in nonoperative outcomes were less consistent. Conclusion. Predominant leg pain patients improved significantly more with surgery than predominant LBP patients. However, predominant LBP patients still improved significantly more with surgery than with nonoperative treatment.
    Spine 02/2011; 36(3):219-29. DOI:10.1097/BRS.0b013e3181d77c21 · 2.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Comparison of intra- and interobserver reliability of digitized manual and computer-assisted intervertebral motion measurements and classification of "instability." To determine if computer-assisted measurement of lumbar intervertebral motion on flexion-extension radiographs improves reliability compared with digitized manual measurements. Many studies have questioned the reliability of manual intervertebral measurements, although few have compared the reliability of computer-assisted and manual measurements on lumbar flexion-extension radiographs. Intervertebral rotation, anterior-posterior (AP) translation, and change in anterior and posterior disc height were measured with a digitized manual technique by three physicians and by three other observers using computer-assisted quantitative motion analysis (QMA) software. Each observer measured 30 sets of digital flexion-extension radiographs (L1-S1) twice. Shrout-Fleiss intraclass correlation coefficients for intra- and interobserver reliabilities were computed. The stability of each level was also classified (instability defined as >4 mm AP translation or 10° rotation), and the intra- and interobserver reliabilities of the two methods were compared using adjusted percent agreement (APA). Intraobserver reliability intraclass correlation coefficients were substantially higher for the QMA technique THAN the digitized manual technique across all measurements: rotation 0.997 versus 0.870, AP translation 0.959 versus 0.557, change in anterior disc height 0.962 versus 0.770, and change in posterior disc height 0.951 versus 0.283. The same pattern was observed for interobserver reliability (rotation 0.962 vs. 0.693, AP translation 0.862 vs. 0.151, change in anterior disc height 0.862 vs. 0.373, and change in posterior disc height 0.730 vs. 0.300). The QMA technique was also more reliable for the classification of "instability." Intraobserver APAs ranged from 87 to 97% for QMA versus 60% to 73% for digitized manual measurements, while interobserver APAs ranged from 91% to 96% for QMA versus 57% to 63% for digitized manual measurements. The use of QMA software substantially improved the reliability of lumbar intervertebral measurements and the classification of instability based on flexion-extension radiographs.
    Spine 01/2011; 36(7):572-80. DOI:10.1097/BRS.0b013e3181e11c13 · 2.45 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ketamine is an N-methyl-d-aspartate receptor antagonist that has been shown to be useful in the reduction of acute postoperative pain and analgesic consumption in a variety of surgical interventions with variable routes of administration. Little is known regarding its efficacy in opiate-dependent patients with a history of chronic pain. We hypothesized that ketamine would reduce postoperative opiate consumption in this patient population. This was a randomized, prospective, double-blinded, and placebo-controlled trial involving opiate-dependent patients undergoing major lumbar spine surgery. Fifty-two patients in the treatment group were administered 0.5 mg/kg intravenous ketamine on induction of anesthesia, and a continuous infusion at 10 microg kg(-1) min(-1) was begun on induction and terminated at wound closure. Fifty patients in the placebo group received saline of equivalent volume. Patients were observed for 48 h postoperatively and followed up at 6 weeks. The primary outcome was 48-h morphine consumption. Total morphine consumption (morphine equivalents) was significantly reduced in the treatment group 48 h after the procedure. It was also reduced at 24 h and at 6 weeks. The average reported pain intensity was significantly reduced in the postanesthesia care unit and at 6 weeks. The groups had no differences in known ketamine- or opiate-related side effects. Intraoperative ketamine reduces opiate consumption in the 48-h postoperative period in opiate-dependent patients with chronic pain. Ketamine may also reduce opioid consumption and pain intensity throughout the postoperative period in this patient population. This benefit is without an increase in side effects.
    Anesthesiology 09/2010; 113(3):639-46. DOI:10.1097/ALN.0b013e3181e90914 · 6.17 Impact Factor
  • The Spine Journal 09/2010; 10(9). DOI:10.1016/j.spinee.2010.07.012 · 2.80 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Biomechanical study of the ProDisc-L in a cadaveric model under pure moment loading. OBJECTIVE.: To determine the kinematic properties of a lumbar spine motion segment and the adjacent level following ProDisc-L disc replacement in the cadaveric spine. Total disc replacement is intended to preserve native motion, in an attempt to prevent accelerated adjacent segment degeneration. The quality and quantity of the motion following TDR may have important consequences on the facet joints of the same motion segment, as well as the motion at the prosthetic component interface. Ten cadaveric lumbar spines were radiographed (L3-L5) and tested under pure moments (+10 Nm to -10 Nm) with an applied follower load (200 N). Load-deformation was tested in flexion/extension, lateral bending (LB), and axial rotation (AR). Range of Motion (ROM) data were recorded. Superior adjacent disc pressure (L3-L4) was measured using subminiature pressure transducers. The L4-L5 disc was subsequently instrumented with a ProDisc-L. Radiographs and biomechanical tests were repeated. Disc replacement significantly reduced extension (ROM 2.2 degrees +/- 0.5 degrees before and 1.2 degrees +/- 0.7 degrees after instrumentation) (P = 0.001), but not flexion (ROM 5.6 degrees +/- 3.1 degrees before and 6.2 degrees +/- 1.2 degrees after) (P = 0.34). Combined flexion/extension motion was marginally reduced (P = 0.517). LB ROM (7.4 degrees +/- 2.0 degrees ) was marginally reduced (P = 0.072) following instrumentation (6.2 degrees +/- 2.5 degrees ), while ROM in AR (3.4 degrees +/- 1.1 degrees ) was significantly increased (4.4 degrees +/- 1.2 degrees ) (P = 0.001). Superior adjacent segment ROM was preserved.No significant differences in disc pressure were observed at the adjacent motion segment before (199 kPa at maximum flexion and 171 kPa at maximum extension) or after disc replacement (252 kPa and 208 kPa, respectively). In cadaveric spines, ROM of operated and adjacent motion segments was preserved following ProDisc-L insertion. Excision of the anterior anulus may increase laxity, which is taken up by the restoration of disc height and lordosis, at the cost of a moderate loss of flexion/extension motion. Adjacent segment kinematics were unaffected following TDR.
    Spine 01/2010; 35(1):26-31. DOI:10.1097/BRS.0b013e3181c4eb9a · 2.45 Impact Factor
  • Marcus Coe, Sohail Mirza, Dilip Sengupta
    [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this review was to examine the randomized controlled trials evaluating fusion surgery for discogenic axial back pain without associated leg pain, spondylolisthesis, or stenosis. Six studies were reviewed: 4 that considered spinal fusion in comparison with nonoperative treatment, and 2 that considered fusion in comparison with artificial disc replacement. We found that methodological difficulties limit the ability to draw definitive conclusions, but that fusion appears superior to unstructured nonoperative treatment, similar to structured nonoperative treatment, and similar to short-term results of artificial disc replacement. Further long term, well-constructed randomized controlled trials are warranted.
    Seminars in Spine Surgery 12/2009; 21(4):246-256. DOI:10.1053/j.semss.2009.08.008
  • [Show abstract] [Hide abstract]
    ABSTRACT: Numerous studies have assessed lumbar interbody fusion, but little data from direct interbody load measurements exists. This manuscript describes an interbody fusion cage with integrated 4-axis load cell that can simulate implant heights of 13, 15, 17, 19 and 21 mm. The calibrated load cell was accurate to within 7.9% for point compressive loads over the central 8 mm x 8 mm region, but up to 26.8% for eccentric loads on the outer 16 mm x 16 mm rim of the device (although typically errors were less than half). Anterior-posterior shear and lateral shear loads did not affect compressive load measurement (<1.0% and <3.5%, respectively). Moments calculated from 4 load sensing corner pillars demonstrated errors below 2.3% in lateral bending and 2.1% in flexion-extension. Although this device does not have the accuracy of other much larger corpectomy implants, it incorporates four channels of load and simulates multiple implant heights, making for a favorable comparison in this restricted space. This device has immediate use in cadaveric testing, providing data previously not attainable, and serves as a novel technological step towards an implantable interbody device with multi-axis load sensing capability. As per the authors' knowledge, no such device has previously been described.
    Medical Engineering & Physics 06/2009; 31(7):846-51. DOI:10.1016/j.medengphy.2009.04.002 · 1.84 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Retrospective, comparative study of clinical and radiologic outcome with independent, blinded observer. To compare the clinical and radiologic outcome of instrumented posterolateral lumbar fusion using local bone versus autogenous iliac crest bone graft (ICBG). There is no published report of outcome of posterolateral spinal fusion using local bone alone for degenerative disorders of the lumbar spine. Seventy-six cases (male 26, female 50) of spinal stenosis, operated during 1996 and 1997 by the senior author, were reviewed. All the cases had decompression and posterior spinal fusion with pedicle screw instrumentation. Forty cases had only local bone graft obtained from decompression, morselized in a bone mill, and 36 cases had autogenous ICBG. Mean age was 60 years (range, 27-83 years). Fusion was performed at one level in 51 (67%), two levels in 16 (21%), three levels in 5 (7%), and four or more levels in 4 cases (5%). Minimum follow-up was 2-years (mean, 28 years; range, 24-72 months). An independent, blinded radiologist rated plain radiographs as fused, indeterminate, or nonunion. There was no difference in age, sex, and diagnosis between the two groups. Overall fusion rate was higher in the ICBG group (75%, 27 of 36) compared with the local bone group (65%, 26 of 40) but not significantly different (P = 0.391). Analyzed separately according to the number of fusion levels, the local bone group achieved similar fusion rate ( approximately 80%) in single-level fusion but a much smaller fusion rate in multilevel fusion (20% vs. 66%, P = 0.029) compared with the ICBG group. Mean improvement in the Oswestry Disability Inventory was 36% in the local bone group and 32% in the ICBG group. There was no significant difference in overall clinical outcome between the two groups. There was no correlation between fusion status and clinical outcome. Blood loss and hospital stay were significantly less in the local bone group; however, blood losswas more significantly related to the sum total number of segments undergoing decompression and fusion. Use of local bone graft alone achieved a similar fusion rate in single-level fusion but a much smaller fusion rate in multilevel fusion compared with the ICBG group. Local bone graft alone achieved a similar clinical outcome but less morbidity irrespective of number of fusion level.
    Spine 05/2006; 31(9):985-91. DOI:10.1097/01.brs.0000215048.51237.3c · 2.45 Impact Factor
  • Source
    Dilip K Sengupta
    Spine 03/2006; 31(4):450. DOI:10.1097/01.brs.0000200051.24623.33 · 2.45 Impact Factor
  • D K Sengupta
    [Show abstract] [Hide abstract]
    ABSTRACT: Soft stabilization has an important role in the treatment of the degenerative lumbar spine. Fusion of one or two motion segments may not make a big difference in the total range of motion of the lumbar spine, but preserving flexibility of a motion segment may prevent adjacent segment disease and may permit disc replacement, even when facet joints need to be excised. A favourable environment is created in the motion segment by unloading the disc and permitting near normal motion, the disc may be able to repair itself or may supplement reparative potential of gene therapy.
    Neurology India 01/2006; 53(4):466-74. DOI:10.4103/0028-3886.22614 · 1.08 Impact Factor
  • Dilip K. Sengupta, Briana Calore
    Seminars in Spine Surgery 06/2005; 17(2):67-72. DOI:10.1053/j.semss.2005.05.003
  • Dilip K Sengupta, Robert C Mulholland
    [Show abstract] [Hide abstract]
    ABSTRACT: An experimental study on cadaver spine and spine model for biomechanical evaluation of a novel dynamic stabilization device. First, to test the hypothesis that in dynamic stabilization of a lumbar spine using pedicle screws and ligament, addition of a fulcrum in front of the ligament can unload the disc. Second, to determine the relationship between the length and stiffness of the fulcrum and the ligament on disc unloading, lordosis and motion preservation. Activity related low back pain may be attributable to abnormal disc loading or abnormal movement. Spinal fusion addresses both the mechanisms, but it has limitations. Soft stabilization with Graf ligament restricts abnormal movement but increases the disc pressure. The Dynesys system uses a plastic cylinder around the ligament to prevent overloading the disc, but it restricts extension and loses lordosis. A novel dynamic stabilization system (fulcrum assisted soft stabilization or FASS) was developed in which a flexible fulcrum was placed in front of a ligament between the pedicle screws. It was hypothesized that the fulcrum should transform the compressive force of a ligament behind into a distraction force in front and unload the disc. Three spine models were developed using wooden blocks for vertebral bodies and neoprene rubber of different hardness for disc. Their load-deformation character was tested and compared with that of the cadaver spine in a spine tester. The spine model with the closest load-deformation property to cadaver spine was then tested for the effect of a FASS system, consisting of high density polythene rod as fulcrums and rubber "O" rings as ligaments. The disc pressure in the spine models were recorded with strain gauge in the center. Application of ligaments alone across the pedicle screws increased the disc pressure, produced a lordosis, and reduced the range of motion. Application of fulcrums reduced the disc pressure and maintained the lordosis. Increasing the fulcrum length resulted in progressive unloading of the disc but increased stiffness of the motion segment. As the fulcrum length approximated the height of the motion segment, the lordosis was lost, and the disc was completely unloaded. Decreasing the lateral bending stiffness of the fulcrum had minimal effect on disc unloading and motion-segment stiffness. The novel FASS system can unload the disc, control the range of motion, and maintain lordosis. These parameters may be controlled with a suitable combination of ligament and fulcrum system. The study provides an indication toward the desirable biomechanical properties of the fulcrum and ligament for future development of a clinically applicable prototype.
    Spine 06/2005; 30(9):1019-29; discussion 1030. · 2.45 Impact Factor

Publication Stats

685 Citations
75.41 Total Impact Points

Institutions

  • 2005–2014
    • Dartmouth–Hitchcock Medical Center
      • Department of Surgery
      LEB, New Hampshire, United States
  • 2002–2004
    • William Beaumont Army Medical Center
      El Paso, Texas, United States
  • 1999–2002
    • University of Nottingham
      • Centre for Sports Medicine
      Nottingham, ENG, United Kingdom