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Hammer L, Ingebrigtsen T, Gulati S, Hara S, Nygaard Ø, Hara KW, Solberg T. Prospects of returning to work after lumbar spine surgery for patients considering disability pension: a nationwide study based on data from the Norwegian Registry for Spine Surgery. Occup Environ Med 2023; 80:447-454. [PMID: 37423749 PMCID: PMC10423536 DOI: 10.1136/oemed-2023-108864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 06/14/2023] [Indexed: 07/11/2023]
Abstract
OBJECTIVES To assess the odds for not returning to work (non-RTW) 1 year after treatment among patients who had applied for or were planning to apply for disability pension (DP-applicant) prior to an operation for degenerative disorders of the lumbar spine. METHODS This population-based cohort study from the Norwegian Registry for Spine surgery included 26 688 cases operated for degenerative disorders of the lumbar spine from 2009 to 2020. The primary outcome was RTW (yes/no). Secondary patient-reported outcome measures (PROMs) were the Oswestry Disability Index, Numeric Rating Scales for back and leg pain, EuroQoL five-dimension and the Global Perceived Effect Scale. Logistic regression analysis was used to investigate associations between being a DP-applicant prior to surgery (exposure), possible confounders (modifiers) at baseline and RTW 12 months after surgery (outcome). RESULTS The RTW ratio for DP-applicants was 23.1% (having applied: 26.5%, planning to apply 21.1%), compared with 78.6% among non-applicants. All secondary PROMs were more favourable among non-applicants. After adjusting for all significant confounders (low expectations and pessimism related to working capability, not feeling wanted by the employer and physically demanding work), DP-applicants with under 12 months preoperative sick leave had 3.8 (95% CI 1.8 to 8.0) higher odds than non-applicants for non-RTW 12 months after surgery. The subgroup having applied for disability pension had the strongest impact on this association. CONCLUSION Less than a quarter of the DP-applicants returned to work 12 months after surgery. This association remained strong, also when adjusted for the confounders as well as other covariates related RTW.
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Affiliation(s)
- Lovise Hammer
- Department of Clinical Medicine, University of Tromsø, Faculty of Health Sciences, Tromso, Norway
| | - Tor Ingebrigtsen
- Department of Clinical Medicine, University of Tromsø, Faculty of Health Sciences, Tromso, Norway
- Department of Neurosurgery, University Hospital of North Norway, Tromso, Norway
| | - Sasha Gulati
- Department of Neurosurgery, St Olavs Hospital Trondheim University Hospital, Trondheim, Norway
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Sozaburo Hara
- Department of Neurosurgery, St Olavs Hospital Trondheim University Hospital, Trondheim, Norway
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Øystein Nygaard
- Department of Neurosurgery, St Olavs Hospital Trondheim University Hospital, Trondheim, Norway
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Karen Walseth Hara
- Department of Public Health and Nursing, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Neurosurgery, Norwegian University of Science and Technology, Trondheim, Norway
| | - Tore Solberg
- Department of Clinical Medicine, University of Tromsø, Faculty of Health Sciences, Tromso, Norway
- Department of Neurosurgery, University Hospital of North Norway, Tromso, Norway
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Sultan KA, Ashraf M, Chaudhary A, Al Salloum L, Ghulam N, Ahmed N, Ismahel H, Farooq M, Iqbal J, Ashraf N. Negative Chronotropic Cardiovascular Changes in Lumbar Spine Surgery: A Potential Spinal-Cardiac Reflex? Asian J Neurosurg 2023; 18:404-409. [PMID: 37397037 PMCID: PMC10313433 DOI: 10.1055/s-0043-1769894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023] Open
Abstract
Cardiovascular changes following lumbar spine surgery in a prone position are exceedingly rare. Over the past 20 years, a total of six cases have been published where patients experienced varying degrees of bradycardia, hypotension, and asystole, which could be attributed to intraoperative dural manipulation. As such, there is emerging evidence for a potential neural-mediated spinal-cardiac reflex. The authors report their experience of negative chronotropy during an elective lumbar spine surgery that coincided with dural manipulation and review the available literature. A 34-year-old male presented with a long-standing history of lower back pain recently deteriorating to bilaterally radiating leg pain, with restricted left leg raise, and numbness at the left L5 dermatomal territory. The patient was an athletic police officer with no comorbidities or past medical history. Magnetic resonance imaging lumbosacral spine revealed spinal stenosis most pronounced at L4/L5 and disc bulges at L3/L4 and L5/S1. The patient opted for lumbar decompression surgery. After an unremarkable comprehensive preoperative workup, including cardiac evaluation (electrocardiogram, echocardiogram), the patient was induced general anesthesia in a prone position. A lumbar incision was made from L2 to S1. When the left L4 nerve root was retracted while removing the prolapsed disc at L4/L5, the anesthetist cautioned the surgeon of bradycardia (34 beats per minute [bpm]), and the surgery was immediately stopped. The heart rate improved to 60 bpm within 30 seconds. When the root was later retracted again, a second episode of bradycardia occurred for 4 minutes with heart rate declining to 48 bpm. The surgery was stopped, and after 4 minutes, the anesthetist administered 600 µg of atropine. The heart rate then rose to 73 bpm within 1 minute. Other potential causes for bradycardia were excluded. The total blood loss was estimated to be 100 mL. He remains well at his 6-month follow-up and has returned to work as normal. Akin to previously published cases, each episode of bradycardia coincided with dural manipulation, which may indicate a possible reflex between the spinal dura mater and the cardiovascular system. Such a rare adverse event may occur even in seemingly healthy, young individuals, and anesthetists should caution the operating surgeon of bradycardias to exclude operative manipulation of the dura as the cause. While this phenomenon is only reported in a handful of lumbar spine surgery cases, it provides evidence for a potential spinal-cardiac physiological reflex in the lumbar spine that may be neural mediated and should be investigated further.
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Affiliation(s)
- Kashif Ali Sultan
- Department of Neurosurgery, Allama Iqbal Medical College, Jinnah Hospital, Lahore, Pakistan
| | - Mohammad Ashraf
- Wolfson School of Medicine, University of Glasgow, Scotland, United Kingdom
| | - Attika Chaudhary
- Wolfson School of Medicine, University of Glasgow, Scotland, United Kingdom
| | - Laulwa Al Salloum
- Wolfson School of Medicine, University of Glasgow, Scotland, United Kingdom
| | - Naseeruddin Ghulam
- Department of Neurosurgery, Allama Iqbal Medical College, Jinnah Hospital, Lahore, Pakistan
| | - Nazir Ahmed
- Department of Neurosurgery, Allama Iqbal Medical College, Jinnah Hospital, Lahore, Pakistan
| | - Hassan Ismahel
- Wolfson School of Medicine, University of Glasgow, Scotland, United Kingdom
| | - Minaam Farooq
- School of Medicine, King Edward Medical University, Lahore, Pakistan
| | - Javed Iqbal
- School of Medicine, King Edward Medical University, Lahore, Pakistan
| | - Naveed Ashraf
- Department of Neurosurgery, Allama Iqbal Medical College, Jinnah Hospital, Lahore, Pakistan
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Dandurand C, Mashayekhi MS, McIntosh G, Singh S, Paquet J, Chaudhry H, Abraham E, Bailey CS, Weber MH, Johnson MG, Nataraj A, Attabib N, Kelly A, Hall H, Rampersaud YR, Manson N, Phan P, Thomas K, Fisher C, Charest-Morin R, Soroceanu A, LaRue B, Dea N. Cost consequence analysis of waiting for lumbar disc herniation surgery. Sci Rep 2023; 13:4519. [PMID: 36934112 PMCID: PMC10024748 DOI: 10.1038/s41598-023-31029-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 03/06/2023] [Indexed: 03/20/2023] Open
Abstract
The economic repercussions of waiting for lumbar disc surgery have not been well studied. The primary goal of this study was to perform a cost-consequence analysis of patients receiving early vs late surgery for symptomatic disc herniation from a societal perspective. Secondarily, we compared patient factors and patient-reported outcomes. This is a retrospective analysis of prospectively collected data from the CSORN registry. A cost-consequence analysis was performed where direct and indirect costs were compared, and different outcomes were listed separately. Comparisons were made on an observational cohort of patients receiving surgery less than 60 days after consent (short wait) or 60 days or more after consent (long wait). This study included 493 patients with surgery between January 2015 and October 2021 with 272 patients (55.2%) in the short wait group and 221 patients (44.8%) classified as long wait. There was no difference in proportions of patients who returned to work at 3 and 12-months. Time from surgery to return to work was similar between both groups (34.0 vs 34.9 days, p = 0.804). Time from consent to return to work was longer in the longer wait group corresponding to an additional $11,753.10 mean indirect cost per patient. The short wait group showed increased healthcare usage at 3 months with more emergency department visits (52.6% vs 25.0%, p < 0.032), more physiotherapy (84.6% vs 72.0%, p < 0.001) and more MRI (65.2% vs 41.4%, p < 0.043). This corresponded to an additional direct cost of $518.21 per patient. Secondarily, the short wait group had higher baseline NRS leg, ODI, and lower EQ5D and PCS. The long wait group had more patients with symptoms over 2 years duration (57.6% vs 34.1%, p < 0.001). A higher proportion of patients reached MCID in terms of NRS leg pain at 3-month follow up in the short wait group (84.0% vs 75.9%, p < 0.040). This cost-consequence analysis of an observational cohort showed decreased costs associated with early surgery of $11,234.89 per patient when compared to late surgery for lumbar disc herniation. The early surgery group had more severe symptoms with higher healthcare utilization. This is counterbalanced by the additional productivity loss in the long wait group, which likely have a more chronic disease. From a societal economic perspective, early surgery seems beneficial and should be promoted.
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Affiliation(s)
- Charlotte Dandurand
- Combined Neurosurgical and Orthopedic Spine Program, Department of Orthopedics Surgery, University of British Columbia, Blusson Spinal Cord Center, 6th Floor, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada.
| | - Mohammad Sadegh Mashayekhi
- Combined Neurosurgical and Orthopedic Spine Program, Department of Orthopedics Surgery, University of British Columbia, Blusson Spinal Cord Center, 6th Floor, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada
| | - Greg McIntosh
- Canadian Spine Outcomes and Research Network, Markdale, ON, Canada
| | - Supriya Singh
- London Health Science Centre Combined Neurosurgical and Orthopaedic Spine Program, Schulich School of Medicine, Western University, London, ON, Canada
| | - Jerome Paquet
- Centre de Recherche CHU de Quebec, CHU de Quebec-Universite Laval, Quebec City, QC, Canada
| | - Hasaan Chaudhry
- Sunnybrook Hospital, University of Toronto, Toronto, ON, Canada
| | - Edward Abraham
- Division of Orthopaedic Surgery, Zone 2, Horizon Health Network, Canada East Spine Centre, Saint John, NB, Canada
| | - Christopher S Bailey
- London Health Science Centre Combined Neurosurgical and Orthopaedic Spine Program, Schulich School of Medicine, Western University, London, ON, Canada
| | - Michael H Weber
- Department of Surgery, Division of Orthopaedics, Montreal General Hospital, McGill University, Montreal, QC, Canada
| | - Michael G Johnson
- Department of Surgery, Section of Orthopedics and Neurosurgery, University of Manitoba, Winnipeg, MB, Canada
| | - Andrew Nataraj
- Division of Neurosurgery, University of Alberta, Edmonton, AB, Canada
| | - Najmedden Attabib
- Division of Neurosurgery, Zone 2, Horizon Health Network, Canada East Spine Centre, Saint John, NB, Canada
| | - Adrienne Kelly
- Sault Area Hospital, Northern Ontario School of Medicine, Sault Ste Marie, ON, Canada
| | - Hamilton Hall
- Department of Surgery, University of Toronto, Toronto, ON, Canada
| | - Y Raja Rampersaud
- Schroeder Arthritis Institute, Krembil Research Institute, University Health Network, Orthopaedics, Department of Surgery, University of Toronto, Toronto, ON, Canada
| | - Neil Manson
- Division of Orthopaedic Surgery, Zone 2, Horizon Health Network, Canada East Spine Centre, Saint John, NB, Canada
| | - Philippe Phan
- Division of Orthopaedic Surgery, University of Ottawa, Ottawa Hospital, Ottawa, ON, Canada
| | - Ken Thomas
- University of Calgary Spine Program, University of Calgary, Calgary, AB, Canada
| | - Charles Fisher
- Combined Neurosurgical and Orthopedic Spine Program, Department of Orthopedics Surgery, University of British Columbia, Blusson Spinal Cord Center, 6th Floor, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada
| | - Raphaele Charest-Morin
- Combined Neurosurgical and Orthopedic Spine Program, Department of Orthopedics Surgery, University of British Columbia, Blusson Spinal Cord Center, 6th Floor, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada
| | - Alex Soroceanu
- Division of Orthopaedic Surgery, University of Ottawa, Ottawa Hospital, Ottawa, ON, Canada
| | - Bernard LaRue
- Départment de chirurgie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Nicolas Dea
- Combined Neurosurgical and Orthopedic Spine Program, Department of Orthopedics Surgery, University of British Columbia, Blusson Spinal Cord Center, 6th Floor, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada
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Won YI, Kim CH, Park HP, Chung SG, Yuh WT, Kwon SW, Yang SH, Lee CH, Choi Y, Park SB, Rhee JM, Kim KT, Chung CK. A cost-utility analysis between decompression only and fusion surgery for elderly patients with lumbar spinal stenosis and sagittal imbalance. Sci Rep 2022; 12:20408. [PMID: 36437360 PMCID: PMC9701767 DOI: 10.1038/s41598-022-24784-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 11/21/2022] [Indexed: 11/29/2022] Open
Abstract
Lumbar spinal stenosis (LSS) and sagittal imbalance are relatively common in elderly patients. Although the goals of surgery include both functional and radiological improvements, the criteria of correction may be too strict for elderly patients. If the main symptom of patients is not forward-stooping but neurogenic claudication or pain, lumbar decompression without adding fusion procedure may be a surgical option. We performed cost-utility analysis between lumbar decompression and lumbar fusion surgery for those patients. Elderly patients (age > 60 years) who underwent 1-2 levels lumbar fusion surgery (F-group, n = 31) or decompression surgery (D-group, n = 40) for LSS with sagittal imbalance (C7 sagittal vertical axis, C7-SVA > 40 mm) with follow-up ≥ 2 years were included. Clinical outcomes (Euro-Quality of Life-5 Dimensions, EQ-5D; Oswestry Disability Index, ODI; numerical rating score of pain on the back and leg, NRS-B and NRS-L) and radiological parameters (C7-SVA; lumbar lordosis, LL; the difference between pelvic incidence and lumbar lordosis, PI-LL; pelvic tilt, PT) were assessed. The quality-adjusted life year (QALY) and incremental cost-effective ratio (ICER) were calculated from a utility score of EQ-5D. Postoperatively, both groups attained clinical and radiological improvement in all parameters, but NRS-L was more improved in the F-group (p = 0.048). ICER of F-group over D-group was 49,833 US dollars/QALY. Cost-effective lumbar decompression may be a recommendable surgical option for certain elderly patients, despite less improvement of leg pain than with fusion surgery.
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Affiliation(s)
- Young Il Won
- grid.254230.20000 0001 0722 6377Department of Neurosurgery, Chungnam National University Sejong Hospital, 20, Bodeum 7-ro, Sejong, 30099 Republic of Korea
| | - Chi Heon Kim
- grid.412484.f0000 0001 0302 820XDepartment of Neurosurgery, Seoul National University Hospital, 101, Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea ,grid.31501.360000 0004 0470 5905Department of Neurosurgery and Medical Device Development, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea ,grid.412484.f0000 0001 0302 820XDepartment of Neurosurgery, Seoul National University College of Medicine, Seoul National University Hospital, 103 Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea
| | - Hee-Pyoung Park
- grid.31501.360000 0004 0470 5905Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine and Hospital, 101, Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea
| | - Sun Gun Chung
- grid.31501.360000 0004 0470 5905Department of Rehabilitation Medicine, Seoul National University College of Medicine and Hospital, 103 Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea
| | - Woon Tak Yuh
- grid.488450.50000 0004 1790 2596Department of Neurosurgery, Hallym University Dongtan Sacred Heart Hospital, 7 Keunjaebong-gil, Hwaseong-si, Gyeonggi-do 18450 Republic of Korea
| | - Shin Won Kwon
- Department of Neurosurgery, Incheon Veterans Hospital, 138, Inju-daero, Michuhol-gu, Incheon, 22182 Republic of Korea
| | - Seung Heon Yang
- grid.31501.360000 0004 0470 5905Department of Neurosurgery and Medical Device Development, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea ,grid.412480.b0000 0004 0647 3378Department of Neurosurgery, Seoul National University Bundang Hospital, 82, Gumi-ro 173 Beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do 13620 Republic of Korea
| | - Chang-Hyun Lee
- grid.412484.f0000 0001 0302 820XDepartment of Neurosurgery, Seoul National University Hospital, 101, Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea ,grid.31501.360000 0004 0470 5905Department of Neurosurgery and Medical Device Development, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea
| | - Yunhee Choi
- grid.412484.f0000 0001 0302 820XDivision of Medical Statistics, Medical Research Collaborating Center, Seoul National University Hospital, 101, Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea
| | - Sung Bae Park
- grid.31501.360000 0004 0470 5905Department of Neurosurgery and Medical Device Development, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea ,grid.412479.dDepartment of Neurosurgery, Seoul National University Boramae Hospital, Boramae Medical Center 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061 Republic of Korea
| | - John M. Rhee
- grid.189967.80000 0001 0941 6502Department of Orthopaedic Surgery, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Kyoung-Tae Kim
- grid.411235.00000 0004 0647 192XDepartment of Neurosurgery, Kyungpook National University Hospital, 130 Dongdeok-ro, Jung-gu, Daegu, 41944 Republic of Korea ,grid.258803.40000 0001 0661 1556Department of Neurosurgery, School of Medicine, Kyungpook National University, 680 Gukchaebosang-ro, Jung-gu, Daegu, 41944 Republic of Korea
| | - Chun Kee Chung
- grid.412484.f0000 0001 0302 820XDepartment of Neurosurgery, Seoul National University Hospital, 101, Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea ,grid.31501.360000 0004 0470 5905Department of Neurosurgery and Medical Device Development, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea ,grid.31501.360000 0004 0470 5905Department of Brain and Cognitive Sciences, Seoul National University, 101, 1, Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea
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DiSilvestro KJ, Bond D, Alsoof D, McDonald CL, Hartnett DA, Hogan WB, Veeramani A, Daniels AH. Preoperative Resilience and Early Postoperative Outcomes following Lumbar Spinal Fusion. World Neurosurg 2022; 163:e573-e578. [PMID: 35427792 DOI: 10.1016/j.wneu.2022.04.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 11/16/2022]
Abstract
BACKGROUND Previous studies identified a correlation between preoperative resilience scores and patient reported outcome measures in several surgical subspecialities. No previous studies, to our knowledge, have analyzed preoperative resilience and patient reported outcomes in lumbar spinal fusion. METHODS Patients undergoing lumbar spinal fusion completed the brief resilience scale preoperatively, in addition to measures of disability (Oswestry Disability index (ODI)), quality of life (PROMIS global physical and mental health scales and EuroQOL5], and leg and back pain (VAS) at pre- and 3-months postoperatively. The 3-month follow-up was selected due to the association with return to work. Multiple linear regression evaluated relationships between resilience and postoperative changes in outcomes measures, controlling for baseline values and body mass index, age, number of levels fused, and severity of comorbidities. RESULTS Ninety-five participants (mean age = 58 years, 56% male) completed the BRS preoperatively and outcome measures before and 3-months after lumbar fusion. On average, participants reported significant postoperative improvements on all outcome measures (p<.001). Higher preoperative resilience scores related to greater postoperative improvements in back and leg pain, global mental and physical health and EuroQol scores (p<0.05), after controlling for baseline values and other covariates. Resilience scores did not significantly correlate with postoperative changes in ODI (p>0.05). CONCLUSIONS Preoperative resilience is associated with improvement in pain, physical and mental health quality of life during the early postoperative period following lumbar spinal fusion. Additional research is needed to determine if improvements are maintained beyond this interval and whether resilience can be modified to optimize outcomes.
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Affiliation(s)
- Kevin J DiSilvestro
- Department of Orthopedic Surgery, Warren Alpert Medical School of Brown University, Rhode Island Hospital, Providence, Rhode Island, USA
| | - Dale Bond
- Department of Psychiatry and Human Behavior, Warren Alpert Medical School of Brown University, The Miriam Hospital, Providence, Rhode Island, USA
| | - Daniel Alsoof
- Department of Orthopedic Surgery, Warren Alpert Medical School of Brown University, Rhode Island Hospital, Providence, Rhode Island, USA
| | - Christopher L McDonald
- Department of Orthopedic Surgery, Warren Alpert Medical School of Brown University, Rhode Island Hospital, Providence, Rhode Island, USA
| | - Davis A Hartnett
- Department of Orthopedic Surgery, Warren Alpert Medical School of Brown University, Rhode Island Hospital, Providence, Rhode Island, USA
| | - William B Hogan
- Department of Orthopedic Surgery, Warren Alpert Medical School of Brown University, Rhode Island Hospital, Providence, Rhode Island, USA
| | - Ashwin Veeramani
- Division of Applied Mathematics, Brown University, Providence, Rhode Island, USA
| | - Alan H Daniels
- Department of Orthopedic Surgery, Warren Alpert Medical School of Brown University, Rhode Island Hospital, Providence, Rhode Island, USA.
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