West III JL, Bradford DS, Ogilvie JW: Results of spinal arthrodesis with pedicle screw-plate fixation. The states with the most cases included California (n = 10, 14.7%), New York (n = 6, 8.8%), Pennsylvania (n = 6, 8.8%), and Illinois (n = 5, 7.3%; Table 2). Spine 13:696706, 1988. Fortunately, most of the complications were minor and transient. Review of neurosurgery medical professional liability claims in the United States. Copyright © 2023 Becker's Healthcare. Accuracy of fluoroscopically-assisted pedicle screw placement: analysis of 1,218 screws in 198 patients. 4. Pedicle screw construct have become one of the most practiced procedure in spinal surgery. In six patients (5.3%) with degenerative spine disease, the disc material had been removed. Spine 15:908912, 1990. A total of 247 screws (9.07%) were BMP, 52 (1.91%) were IMP, and 29 (1.06%) were considered SAR. Junctional problems were recorded as pathologic changes of the adjacent motion segments, just above and below the instrumented and fused segments. A retrospective review of charts, XRs and low-dose CT scans of 127 patients who underwent spinal fusion with pedicle screws for spinal deformity was performed. Placement of thoracolumbar pedicle screws using three-dimensional image guidance: experience in a large patient cohort. (A) Anteroposterior and (B) lateral radiographs taken 1 year after surgery show upper screw breakage in the application of a short Cotrel-Dubousset construct in a T12 burst fracture. (%), Pseudarthrosis requiring revision surgery. Department of Neurosurgery, Spine Division, Duke University Medical Center, Durham, North Carolina; and, Malpractice liability and defensive medicine: a national survey of neurosurgeons, Defensive medicine among high-risk specialist physicians in a volatile malpractice environment, Defensive medicine: a culprit in spiking healthcare costs, Incidence and costs of defensive medicine among orthopedic surgeons in the United States: a national survey study, Defensive medicine in U.S. spine neurosurgery, Personal consequences of malpractice lawsuits on American surgeons. GraphPad Prism version 6.01 for Windows was used for all descriptive analyses (GraphPad Software). Would you like email updates of new search results? Nyquist followed a medical malpractice lawsuit against Dr. Masnyk for his surgical error, alleging that the surgeon had improperly positioned the right L4 pedicel screw which had resulted in a nerve root injury and Nyquists subsequent foot drop. Continued clinical experience with various pedicle screw implant systems has led to ongoing improvements in system design to minimize implant failure rates and to improve ease of system application. Analysis and interpretation of data: Sankey, TT Than. This study revealed an overall accuracy rate of 95.2% of mainly percutaneously inserted pedicle screws according to the classification of Zdichavsky et al. Several limitations should be carefully considered when interpreting our results. The median time to case closure was 56.3 (35.267.2) months when ruled in favor of the plaintiff (i.e., patient) compared to 61.5 (51.477.2) months for defendant (surgeon) verdicts (p = 0.117). Operative information including fusion level, number of levels fused, level of misplaced screw(s), single versus multiple misplaced screw(s), presence of known CSF leakage, and primary injury due to screw misplacement was also collected. Fager CA. For more information, please refer to our Privacy Policy. Judgment information associated with a defendant (surgeon) versus plaintiff (patient) ruling, trial versus settlement versus arbitration decision, award amount, and time to decision or case closure from index surgery was also recorded. Materials and Methods Sixty . Studies have shown that the greatest proportion of malpractice claims in spine surgery are related to procedural error,10,11,14,16,17,19 often resulting in the highest payouts.11,20 For spine surgery, one common area for the potential avoidance of malpractice claims and subsequent payouts involves misplaced pedicle and/or lateral mass screws, which occurs in approximately 14%55% of cases using standard techniques and results in neurological injury and/or durotomy in approximately 1%8% of cases.21 Misplaced screws have the potential to cause severe and sometimes permanent neurological deficits, including spinal cord and/or nerve root injury,21 as well as to decrease the stability of the fusion construct, leading to delayed complications related to pseudarthrosis. $ = US$; MW = Midwest; NE = Northeast; SE = Southeast; SW = Southwest; W = West. Twenty-one patients (18.8%) had thoracolumbar injuries, and loss of immediate postoperative deformity correction ranged from 1.4 to 4.5. The screws were needed to stabilize the spine and fix the fused vertebrae in place. Many technological advances have been made over the past several decades in an effort to improve the accuracy of screw placement in spine surgery.3436 For example, 3D fluoroscopybased image guidance has been shown to decrease the pedicle breach rate in several studies compared to the rate with 2D fluoroscopic guidance or the freehand technique, particularly in deformity and revision surgeries.21,34,36,37 CT guidance or intraoperative confirmation has also been shown to further improve the accuracy of pedicle screw placement,3638 with reported accuracy rates of 89%100% reported in the literature, depending on the authors breach criteria.35 However, it is important to note that the use of this technology is often accompanied by a lower threshold for intraoperative screw revision, sometimes leading to higher rates of replaced screws.33 Arguably, these improved trajectories may avoid iatrogenic neurological deficits due to prolonged nerve root compression or even improve the stability of the construct;34,37 however, prospective studies of long-term outcomes and rates of revision surgery remain sparse in the literature. Pedicle screw fixation is an effective but demanding method to treat various spinal disorders and is associated with a significant complication rate. INCLUDE WHEN CITING DOI: 10.3171/2020.8.FOCUS20600. Spine surgery has been disproportionately impacted by medical liability and malpractice litigation, with the majority of claims and payouts related to procedural error. Additional survey data have shown that 50% of physicians exhibit at least a temporary loss of self-esteem after a malpractice claim, and at least 25% experience depression.22 As stated above, the average neurosurgeon spends 27.2% of his or her entire career in an open malpractice claim,10 and each case can take an average of 5.1, 5.0, and 3.4 years for defendant verdicts, plaintiff rulings, and settlements, respectively.7,15 Likewise, neurosurgeons have a higher risk than practitioners in other specialties of being named in multiple malpractice suits given the particularly high-risk nature of the specialty.10 Even when found in favor of the defendant (surgeon), each case ultimately takes a substantial emotional and financial toll on the physician(s) involved. In four of these patients, bent screws occurred at 8 to 10 months after surgery; in three patients, broken screw necks were seen 1 year after surgery and in two patients, tulip screw plug dislodgments were observed at 4 and 6 months postoperatively, respectively. 23. Accessibility Lawsuit information regarding the plaintiffs age at the time of the malpractice claim, sex, postoperative complaint, indication for index surgery, defendant surgeon specialty (neurosurgery vs orthopedics), and delayed diagnosis or treatment, as well as case location by state and case year, was obtained. J Neurosurg Spine. These numbers are in line with the current literature. Intraoperative and postoperative complications were recorded by the authors and the results were evaluated by an independent observer. Dr. K. D. Than is a consultant for Bioventus and receives honoraria from DJO and LifeNet Health. Presse Med 78:14471448, 1970. A p < 0.05 was considered statistically significant. In several of the studies in the spinal literature, the contention that instrumentation improves arthrodesis rates, considering that nonunion contributes to a poor outcome in spinal arthrodesis is favored. Spine 17:834837, 1992. The incidence of screw failure, which can occur despite solid arthrodesis, 7 in the current series was 8% and mainly involved patients with thoracolumbar injury. Guzek RH, Mitchell SL, Krakow AR, Harshavardhana NS, Sarkissian EJ, Flynn JM. Moffatt-Bruce SD, Ferdinand FD, Fann JI. Per-patient analysis showed 23 (18.11%) of patients had all screws AP. Administrative/technical/material support: Mehta, Wang, KD Than. Dr. Goodwin has received grants from the Burroughs Wellcome Fund, North Carolina Spine Society, and Robert Wood Johnson Harold Amos Medical Faculty Development Program and the NIH/NINDS K12 NRCDP Physician Scientist Award. Mayo Clinic uses the latest robot-assisted technology when indicated to enhance surgical precision in these procedures. Placement of the pedicle screws in the thoracolumbar and lumbar spine is a technically demanding procedure. Per-patient analysis reveals more concerning numbers toward screw misplacement. The literature gave a range of screw misplacement rates detected on postoperative imaging of between 1% and 18%, with the rate generally considered to be around 10%. Phone/Fax: 30-2810-318361; E-mail: [emailprotected]. Ultimately, additional prospective, multiinstitutional large-volume studies are needed to validate these findings, and future studies should evaluate the long-term impact on the routine use of intraoperative imaging confirmation and/or computer- or robot-assisted navigation on the frequency and success of malpractice claims related to misplaced pedicle and lateral mass screws. leg pain. It is easier to confuse a jury than convince a judge: the crisis in medical malpractice. Acta Neurochir (Wien). 26 They support that after a lengthy symptom-free period, segments next to a fused segment can break down and the segment next to the adjacent segment is almost as likely to break down as the adjacent segment. It should be used by experienced and qualified surgeons who are familiar with the pitfalls associated with its use. Dalenberg DD, Asher MA, Robinson RG, Jayaraman G: The effect of a stiff spinal implant and its loosening on bone mineral content in canines. 29. The rate of misplaced pedicle screws ranges from 1.1% to 28.8%, 10 although neurologic injury from misdirected pedicle screws has been reported to occur in 0% to 12% of patients. However, 5-10% of those misplaced screws are cause for concern." "To rectify this, we must have access to imaging devices during the procedure. Spine 14:472476, 1989. A misplacement rate of more than 20 % (129 misplaced screws out of 608) seems to be unacceptable compared to only 4.5 % misplacements when using CT-navigation leading to the conclusion that pedicle screw instrumentation in the middle and upper thoracic area should be carried out with the help of navigation only. In the current series, there were no cases of screw misplacement or vascular or neurologic complications caused by implant application. The patient suffered permanent nerve damage as a result of the puncture. Smith TR, Hulou MM, Yan SC, et al. Safety and efficacy of pedicle screw placement using intraoperative computed tomography: consecutive series of 1148 pedicle screws. Spine 13:10121018, 1988. Pedicle screw accuracy in thoracolumbar fractures- is routine postoperative CT scan necessary? The majority of plaintiffs were male (n = 44, 64.7%), and the median age among all cases was 46 years (range 3757 years). Screw misplacement. Clin Orthop 203:717, 1986. National Library of Medicine Disclaimer. matte black square deadbolt; roberts point park fishing report; qr code on binax covid test; mff premium character list. Dr. Abd-El-Barr is a consultant for Spineology. A review of medicolegal malpractice suits involving cervical spine: what can we learn or change? 2. Characteristics of medicolegal cases related to misplaced screws in spine surgery. 13. This site needs JavaScript to work properly. Importantly, these advanced technologies are not always readily available or the standard of care and cannot supplant a thorough understanding of operative anatomy, a high-quality surgical technique, and general complication-avoidance measures. Mohar J, Vali M, Podovovnik E, Mihali R. Eur Spine J. All Rights Reserved. However, the medicolegal impact of misplaced screws on spine surgery has not been directly reported in the literature. Instead, the defense offered up an alternative explanation for Nyquists foot drop. Harris RI, Wiley JJ: Acquired spondylolysis as a sequel to spine fusion. Katonis, Pavlos MD*; Christoforakis, Joseph MD*; Aligizakis, Agisilaos C. MD*; Papadopoulos, Charalampos MD*; Sapkas, George MD, DSc**; Hadjipavlou, Alexander MD*. In the current study, the arthrodesis rate of 89.4% compares favorably with other previously reported series in the spinal literature, most of which use radiographic means to access the status of the spinal arthrodesis. Plaintiff award amounts were adjusted for inflation as of April 2020 using an online inflation calculator provided by the US Bureau of Labor Statistics (https://www.bls.gov/data/inflation_calculator.htm). None of these complications resulted in additional surgery or in a significant increase of morbidity. Conception and design: Sankey, KD Than. doi: 10.1097/BRS.0b013e31822a2e0a. 2011;306(10):1088. Unilateral nonunion was seen in three patients (2.7%), associated with implant failure in one of the patients. Quraishi NA, Hammett TC, Todd DB, et al. Each case was then carefully screened for relevance and sufficient data. In the current study, only five patients with junction problems above the instrumented area were observed with the following probable predisposing factors: an already degenerative disc, coronal imbalance, very long arthrodesis, and old age. Medical malpractice litigation has made a significant impact on spine surgery, with many spine surgeons avoiding complex cases or practicing other defensive medicine tactics in an effort to avoid being sued.5 Moreover, the majority of neurosurgeons spend more than 10% of their annual revenue on malpractice insurance,1,14 and the excessive financial risk of litigation is even leading some insurers to no longer offer coverage to spine surgeons.19 A 2011 study in the New England Journal of Medicine found that 19.1% of neurosurgeons are named as a defendant in a malpractice suit each year (highest of any specialty).12 Moreover, 88% of physicians in high-risk specialties, like neurosurgery, are involved in a lawsuit by age 45, increasing to a concerning 99% by 65 years of age.12 Such litigation places a substantial financial, temporal, and emotional burden on physicians in high-risk specialties, with studies showing that up to 72% of neurosurgeons1 admitted that their fear of litigation significantly influenced their practice,25 with many avoiding high-risk patients altogether.1 Similarly, Nahed et al. Malpractice claims in spine surgery in Germany: a 5-year analysis. 19. Br J Neurosurg. Moreover, several cases stated that the surgeon used only the anteroposterior or the lateral view, but not both, and the plaintiffs counsel used this information in support of their claim. Mean amounts awarded SD to plaintiffs by jury trial (n = 13) versus settlement/arbitration (n = 7), adjusted for inflation as of April 2020. Routine CT scans were taken in all patients. Two patients with associated injuries in the lower limbs had deep venous thrombosis develop, three patients had pneumonia develop, and four patients with neurologic impairment had urinary tract infections develop. * Patient safety: disclosure of medical errors and risk mitigation. Cook County Surgeons Cut Common BIle Duct During Surgery, But Jury Finds for Defendants Irwin v. Alan Loren, M.D. Clin Orthop 284:8090, 1992. Intraoperative pedicle fractures requiring further points of fixation. We attribute the 24.1% disc space narrowing in the instrumented segments mainly to the severe injury of the disc and communication of the end plate in burst fractures, which could accelerate the disc degeneration and narrowing. Malpractice issues in neurological surgery. Categorical and continuous data are described as frequency (percentage) and median (interquartile range), respectively, except for the use of mean standard deviation for award amounts since both nominal and inflation-adjusted award totals passed (alpha = 0.05) the DAgostino-Pearson omnibus normality test. Lorenz M, Zindrick M, Schwaegler P, et al: A comparison of single level fusion with and without hardware. demonstrated that the number of hospital discharges for spinal fusion increased 2.4 times (137%) from 174,223 to 413,171 (p < 0.001) between 1998 and 2008.32 The true frequency of malpositioned pedicle and lateral mass screws is likely underestimated in spine surgery given the fact that the majority of misplaced screws, as well as the potential complications related to them, are not reported in practice and may be clinically silent. Deyo RA, Mirza SK, Martin BI. 5-7 Materials and Methods This is a retrospective study of kyphotic spondylitis tuberculosis (Stb) patients conducted at Fatmawati General Hospital, Jakarta, Indonesia, through the year 2020-2021. 18. Background The objective of this cadaveric study was to analyze the effects of iatrogenic pedicle perforations from screw misplacement on the mean pullout strength of lower thoracic and lumbar pedicle screws. 2014;96(4):266270. Recently, robot-assisted pedicle screw implantation has been increasingly utilized at large-volume academic centers. Health Aff (Millwood). A neurologic deficit developed in one patient (0.9%) who had partial bilateral drop feet after reduction of L4L5 spondylolisthesis. A total of 69 patients (mean age, 67.416 . The remaining eight patients, including two patients with spinal trauma, five patients with infection, and one patient with a tumor, had anterior and posterior procedures. The rate of reoperation for screw misplacement per screw was 0.17%. Edmunds I, Cummine J, Fearnside M: Prevention of dislodgement of Cotrel-Dubousset rods from tulip screws. 13 Whitecloud et al 35 reported 15% neurologic complications, 5% being caused by incorrect screw placement. Screw Malposition: Are There Long-term Repercussions to Malposition of Pedicle Screws? Erwin WD, Dickson JH, Harrington PR: Clinical review of patients with broken Harrington rods. Moreover, local court rulings are not included in the Westlaw Edge database; however, this is unlikely to present meaningful bias given that malpractice claims are generally filed in state courts. Quinnell RC, Stockdale HR: Some experimental observations of the influence of a single lumbar floating fusion on the remaining lumbar spine. Likewise, cases are uploaded on a voluntary basis by state and federal judges and courts, which may lead to selection bias. Sarwahi V, Ayan S, Amaral T, Wendolowski S, Gecelter R, Lo Y, Thornhill B. Spine Deform. Although the rationale for using pedicle screw fixation is fairly clear, controversy continues regarding the application of pedicle instrumentation for spine arthrodesis, especially on the degenerative lumbar spine. Harrington PR, Tullos HS: Reduction of severe spondylolisthesis in children. Krag MH, Beynnon BD, Pope MH, et al: An internal fixator for posterior application to short segment of the thoracic, lumbar, or lumbosacral spine. 2022 Jun;8(2):234-241. doi: 10.21037/jss-22-28. Eur Spine J. Epub 2021 Aug 28. 12. Despite commonly used, questions remain about their safety especially for the thoracic spine and in deformity where difficulty in positioning can lead to pedicle breach and adjacent structures injury. Spine surgery has been disproportionately impacted by medical liability and malpractice litigation, with the majority of claims and payouts related to procedural error. Spine Deform. However, the highest offer had been a combined $300,000 from the two defendants. To investigate intraoperative reinsertion of percutaneous pedicle screw (PPS) with intraoperative CT-based navigation and to evaluate the rate of deviation of PPS at postoperative radiographic examination. Two-dimensional (2D) fluoroscopy-guided percutaneous pedicle screw (PPS) placement is currently the most widely applied instrumentation for minimally invasive treatment of spinal injuries requiring stabilization. 2016;124(5):15241530. reported that 69.3% of neurosurgeons who responded to their survey saw every patient as a potential lawsuit.1. 13 Whitecloud et al 35 reported 15% neurologic complications, 5% being caused by incorrect screw placement. Spine arthrodesis was evaluated with plain AP and lateral radiographs taken 1 year after surgery. The link was not copied. Five patients had uneventful early postoperative course. Unauthorized use of these marks is strictly prohibited. 2014;20(6):636643. On April 6, a Union County, N.J., jury awarded a plaintiff $4.5 million over a botched spine surgery. Image intensification and the technique recommended by Weinstein et al 32 was used for screw placement in the lumbar vertebrae, whereas Chopin blocks (Medtronic Sofamor Danek) with two screws diverging bilaterally were used for sacral fixation. Nottmeier EW, Seemer W, Young PM. In addition, seven (6.3%) dural tears occurred during the decompression and none occurred during instrumentation. The plaintiff underwent revision surgery in May 2013. 20. However, only a few complications were related to a poor clinical outcome. An official website of the United States government. Critically revising the article: all authors. Personal consequences of malpractice lawsuits on American surgeons. Rajaee SS, Bae HW, Kanim LE, Delamarter RB. Careers. Pedicle screws are used by spine surgeons as part of a fusion in which two adjacent bones in the spine are combined together as one. The case facts centered on a spinal surgery the 34 year-old plaintiff had undergone at Central DuPage Hospital. George Sapkas, MD, DSc; and Panayiotis J. Papagelopoulis, MD, DScGuest Editors. J Am Coll Surg. EOS System Courtesy of EOS imaging. 39. Percentage of cases per US region (center). Bethesda, MD 20894, Web Policies Copyright 1944-2023 American Association of Neurological Surgeons, Copy this link, or click below to email it to a friend. Spine 6:615619, 1981. 3). Safety and accuracy of robot-assisted versus fluoroscopy-guided pedicle screw insertion for degenerative diseases of the lumbar spine: a matched cohort comparison. All the incidental dural tears were repaired immediately and produced no clinical sequelae. Reviewed submitted version of manuscript: all authors. With increasing pedicle screw usage, the number of patients with misplaced screws will likely increase proportionally. The amount awarded was not significantly different across US regions (p = 0.9; Fig. To evaluate the accuracy of pedicle screw placement using a novel classification system to determine potentially significant screw misplacement. Spine (Phila Pa 1976). Level of evidence: A Cotrel-Dubousset spinal system (Medtronic Sofamor Danek, Memphis, TN) was used in all patients and the total number of screws used was 658. Plaintiff's expert was prepared to testify at trial that these complaints are characteristic of a malpositioned screw impinging upon a neural structure. In their meta-analysis of nine randomized controlled trials, Li et al. Clinical Orthopaedics and Related Research, Get new journal Tables of Contents sent right to your email inbox, The Association of Bone and Joint Surgeons, Complications and Problems Related to Pedicle Screw Fixation of the Spine, Articles in Google Scholar by Pavlos Katonis, MD, Other articles in this journal by Pavlos Katonis, MD, Privacy Policy (Updated December 15, 2022). Roy-Camille R, Roy-Camille M, Demeulenaere C: Osteosynthese du rachis dorsal, lombaire et lombo-sacre par plaque metalliques vissees dans les pedicules vertebraux et es apophyses articularies. Misplaced pedicle and lateral mass screws result in a considerable risk of malpractice litigation against spine surgeons. In five patients with thoracolumbar injuries, who were the first treated in the current series, and in four patients with fractures in the lower lumbar spine, two-segment fixation was used. Larson AN, Santos ER, Polly DW Jr, Ledonio CG, Sembrano JN, Mielke CH, Guidera KJ. 2011;24(1):1519. These risks can be minimized by the judicious use of instrumentation by experienced surgeons for specific indications as supported by the literature. Defensive medicine among high-risk specialist physicians in a volatile malpractice environment. Scarone P, Vincenzo G, Distefano D, et al. Results. Despite this problem, the clinical result was excellent. Eur Spine J. In this example, the surgeon replaced the misplaced screw prior to leaving the operating room, which arguably played a significant role in the jury ruling in favor of the defendant (surgeon). Before Error in trends, major medical complications, and charges associated with surgery for lumbar spinal stenosis in older adults. Notwithstanding these concessions, the MDU argued that misplacement of pedicle screw tracts was common in surgery of this kind, even in experienced and competent hands. PMC pedicle screws sagittal alignment spinal fusion surgical guides Spinal fusion is used to treat a range of conditions associated with spinal column such as intervertebral disc degeneration and scoliosis [ 1 ]. In addition, studies have shown that over 85% of malpractice claims are either dismissed or settled out of court,14 which likely results in a high degree of underreporting. 37. Zdeblick TA: A prospective randomized study of lumbar fusion: Preliminary results. The screws were needed to stabilize the spine and fix the fused vertebrae in place. In the current series, including general complications, only 48 patients (43%) had no notable complication and the remaining 64 patients (57%) had one or more complications. 2012;41(2):6973. Start; O firmie; Usugi; Serwis; Realizacje i porady; Kontakt Although the rate of the reported complications was high, the final outcome of the patients was not affected significantly. Clin Orthop 227:1023, 1988. Spine J. Malpractice litigation following spine surgery. These complications may have resulted from powerful bending movement acting on the screw at its entry point to the bone. 2022 Dec;31(12):3544-3550. doi: 10.1007/s00586-022-07427-0. Both of these patients complained of thigh pain but refused any additional surgery. Of the 112 patients, 57 patients had a lumbar degenerative disorder, (lumbar degenerative spinal canal stenosis in 23 patients, degenerative or spondylolytic spondylolisthesis in 12 patients, postlaminectomy instability or stenosis in 20 patients, and recurrent disc prolapse in two patients), 42 patients had spinal cord injury, eight patients had infection, and five patients had a spinal tumor (Table 1). The average age of the patients was 47 years and the average followup was 35 months. The standard imaging technique for pedicle screw insertion is two-dimensional images obtained from C-arm-type X-ray fluoroscopy. 2011;365(7):629636. One of the common means of doing so is to place a screw into each of two adjacent spinal bones (vertebrae), and then a rod between them. 2018;29(4):397406. In six of these patients with injuries at the thoracolumbar area (four patients with bent screws and two patients with broken screws), the loss of correction ranged from 3 to 4.5 without change of anatomic reduction (Fig 1). This was followed by pseudarthrosis requiring revision surgery, present in 14.3% (n = 3) and 14.9% (n = 7) of plaintiff- and defendant-awarded cases, respectively (p = 0.99). Hecht N, Kamphuis M, Czabanka M, et al. What can spine surgeons do to improve patient care and avoid medical negligence suits? Study design: General complications were considered those developing during and after surgery that were not directly related to instrumentation. NCI CPTC Antibody Characterization Program. J Neurosurg Spine. Dr. K. D. Than is a consultant for Bioventus and receives honoraria from DJO and LifeNet Health. Spine 6:263267, 1981. Pedicle instrumentation in the thoracolumbar and lumbar spine is a technically challenging procedure. In two patients in the current series, dislodgement of the rods from tulip screws occurred, as reported originally by Edmunds et al.