Dilip K Sengupta

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

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Publications (52)90.79 Total impact

  • Dilip K Sengupta · Haibo Fan
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    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.
    No preview · Article · Feb 2014 · Spine
  • Dilip K. Sengupta · John P. OʼBrien

    No preview · Article · Feb 2014 · Spine
  • Dilip K. Sengupta · John P. OʼBrien

    No preview · Article · Feb 2014 · Spine
  • Peng Huang · Dilip K Sengupta
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    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.
    No preview · Article · Jan 2014 · Spine
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    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.
    Preview · Article · Apr 2013
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    Dilip K Sengupta · Harry N Herkowitz
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    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.
    Preview · Article · Nov 2012
  • Article: Letters.
    Dilip K Sengupta

    No preview · Article · Sep 2012 · Spine
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    ABSTRACT: Magnetic resonance (MR) imaging in patients with persistent low back pain and sciatica effectively demonstrates spine anatomy and the relationship of nerve roots and intervertebral disks. Except in cases with nerve root compression, disk extrusion, or central stenosis, conventional anatomic MR images do not help distinguish effectively between painful and nonpainful degenerating disks. Hypoxia, inflammation, innervation, accelerated catabolism, and reduced water and glycosaminoglycan content characterize degenerated disks, the extent of which may distinguish nonpainful from painful ones. Applied to the spine, "functional" imaging techniques such as MR spectroscopy, T1ρ calculation, T2 relaxation time measurement, diffusion quantitative imaging, and radio nucleotide imaging provide measurements of some of these degenerative features. Novel minimally invasive therapies, with injected growth factors or genetic materials, target these processes in the disk and effectively reverse degeneration in controlled laboratory conditions. Functional imaging has applications in clinical trials to evaluate the efficacy of these therapies and eventually to select patients for treatment. This report summarizes the biochemical processes in disk degeneration, the application of advanced disk imaging techniques, and the novel biologic therapies that presently have the most clinical promise.
    No preview · Article · Jul 2012 · Radiology
  • Dilip K. Sengupta · Dr. Med · Haibo Fan

    No preview · Article · Oct 2011
  • Dilip Sengupta · James Sanders · Douglas Burton

    No preview · Article · Oct 2011 · The Spine Journal
  • Dilip Sengupta · James Sanders · Douglas Burton · Reginald Knight

    No preview · Article · Oct 2011 · The Spine Journal
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    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.
    No preview · Article · Jun 2011 · Journal of the Indian Medical Association
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    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.
    No preview · Article · Apr 2011 · Spine
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    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.
    Preview · Article · Feb 2011 · Spine
  • Dilip K. Sengupta · Bhavuk Garg

    No preview · Article · Sep 2010 · The Spine Journal
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    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.
    Full-text · Article · Sep 2010 · Anesthesiology

  • No preview · Article · Sep 2010 · The Spine Journal
  • Dilip Kumar Sengupta · John K Webb

    No preview · Article · Jan 2010 · Indian Journal of Orthopaedics
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    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.
    No preview · Article · Jan 2010 · Spine
  • Marcus Coe · Sohail Mirza · Dilip Sengupta
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    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.
    No preview · Article · Dec 2009 · Seminars in Spine Surgery

Publication Stats

1k Citations
90.79 Total Impact Points


  • 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
    • The Texas Back Institute Research Foundation
      Dallas, Texas, United States