Tag Archive | opioid

Predictors of Prolonged Analgesic Use after Joint Replacement

OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Eric Secrist, MD in response to a recent study in Arthritis Research & Therapy.

There has been a proliferation of research regarding postoperative opioid usage after joint arthroplasty due to the widespread opioid epidemic. But Rajamäki and colleagues from Tampere University in Finland took the unique approach of also analyzing acetaminophen and NSAID usage in addition to opioids. The authors used robust data from Finland’s nationwide Drug Prescription Register, which contains reliable information on all medications dispensed from pharmacies, including over-the-counter drugs.

After excluding patients who underwent revision surgery or had their knee or hip replaced for a diagnosis other than osteoarthritis, the authors analyzed 6,238 hip replacements in 5,657 patients and 7,501 knee replacements in 6,791 patients, all performed between 2002 and 2013. The mean patient age was 68.7 years and the mean BMI was 29.

One year postoperatively, 26.1% of patients were still filling prescriptions for one or more analgesics, including NSAIDs (15.5%), acetaminophen (10.1%), and opioids (6.7%). Obesity and preoperative analgesic use were the strongest predictors of prolonged analgesic medication usage 1 year following total joint arthroplasty. Other predictors of ongoing analgesic usage included older age, female gender, and higher number of comorbidities. Patients who underwent knee replacement used the 3 analgesics more often than those who underwent hip replacement.

This study had all of the limitations inherent in retrospective database analyses. Additionally, it was not possible for the authors to determine whether patients took analgesic medications for postoperative knee or hip pain or for pain elsewhere in their body. Finally, the authors utilized antidepressant reimbursement data as a surrogate marker for depression and other medications as a surrogate for a Charlson Comorbidity Index.

Figure 2 from this study (shown below) reveals 2 important findings. First, total joint arthroplasty resulted in a significant decrease in the proportion of patients taking an analgesic medication, regardless of BMI. Second, patients in lower BMI categories were less likely to use analgesics both preoperatively and postoperatively.

The findings from this study may be most useful during preoperative counseling for obese patients, who often present with severe joint pain but are frequently told they need to delay surgery to lose weight and improve their complication-risk profile. Based on this study, those patients can be counseled that losing weight will not only decrease their complication risk, but also decrease their reliance on medications for the pain that led them to seek surgery in the first place.

Eric Secrist, MD is a fourth-year orthopaedic resident at Atrium Health in Charlotte, North Carolina.

What’s New in Spine Surgery 2020

Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of OrthoBuzz summaries of these “What’s New” articles. This month, co-author Jacob M. Buchowski, MD, selected the 5 most clinically compelling findings from the >30 studies summarized in the June 17, 2020 “What’s New in Spine Surgery.

Adult Spinal Deformity
A recent randomized controlled trial compared operative vs nonoperative treatment among 63 adult patients with symptomatic lumbar scoliosis. An additional 223 patients were included in an observational arm of the study. At 2 years, 64% of the randomized patients in the nonoperative group had crossed over to the operative group. In an as-treated analysis, surgery was associated with superior improvement, but the high crossover rate precludes making firm comparative conclusions.

Spinal Cord Injuries
—A small study of 3 subjects1 who had sustained a spinal cord injury investigated the delivery of spatially selective stimulation to posterior nerve roots innervating the lumbosacral spinal cord through an implantable pulse generator with real-time triggering capability. This method reestablished adaptive control over previously paralyzed muscles, and subjects were eventually able to walk or bike during spatiotemporal stimulation.

Cervical Myelopathy
—A prospective study of >700 patients with degenerative cervical myelopathy2 examined the impact of surgical management on neck pain outcomes. Using the Neck Disability Index at baseline and at 6, 12, and 24 months postoperatively, researchers found significant improvement in functional and pain scores that met or exceeded the minimum clinically important difference at all follow-up time points.

Lumbar Stenosis
—A retrospective study of >1,800 patients with symptomatic lumbar stenosis3 investigated whether pain improvements could be obtained surgically with decompression alone without fusion. At 1 year after surgery, decompression alone was associated with significant improvement in all patient-reported outcomes, suggesting that a concomitant fusion may not be required in such cases.

Opioid Consumption
—A retrospective study of nearly 29,000 patients4 examined the effects of chronic preoperative opioid therapy on medium- and long-term outcomes after lumbar arthrodesis surgery. Postoperatively, chronic opioid use prior to surgery was associated with an increased risk of 90-day emergency department visits and prolonged 1- and 2-year narcotic use.

References

  1. Wagner FB, Mignardot JB, Le Goff-Mignardot CG, Demesmaeker R, Komi S, Capogrosso M, Rowald A, Se´añez I, Caban M, Pirondini E, Vat M, McCracken LA, Heimgartner R, Fodor I, Watrin A, Seguin P, Paoles E, Van Den Keybus K, Eberle G, Schurch B, Pralong E, Becce F, Prior J, Buse N, Buschman R, Neufeld E, Kuster N, Carda S, von Zitzewitz J, Delattre V, Denison T, Lambert H, Minassian K, Bloch J. Courtine G. Targeted neurotechnology restores walking in humans with spinal cord injury. Nature. 2018 Nov;563(7729):65-71. Epub 2018 Oct 31.
  1. Schneider MM, Tetreault L, Badhiwala JH, Zhu MP, Wilson J, Fehlings MG. 42. The impact of surgical decompression on neck pain outcomes in patients with degenerative cervical myelopathy: results from the multicenter prospective AOSpine studies. Spine J. 2019 Sep;19(9):S21.
  2. Bech-Azeddine R, Fruensgaard S, Andersen M, Carreon LY. 215. Outcomes of decompression without fusion in patients with lumbar spinal stenosis with back pain. Spine J. 2019 Sep;19(9):S106.
  3. Eisenberg JM, Kalakoti P, Hendrickson NR, Saifi C, Pugely AJ. 142. Impact of preoperative chronic opioid therapy on long-term outcomes, reoperations, complications and resource utilization after lumbar arthrodesis. Spine J. 2019 Sep; 19(9):S68-9.

Open-Access JBJS Supplement: Pain Management Research

In November 2019, OrthoBuzz promised readers more details from the Pain Management Research Symposium held that month (see related post), which was supported by a grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Those details are now available in the form of a JBJS Supplement containing 12 articles generated from that convening of > 30 orthopaedic researchers and journal editors. The Symposium focused on the unique challenges of designing studies that will answer pressing questions about pain management related to musculoskeletal conditions and procedures.

The content of this open-access Supplement ranges from subspecialty-specific considerations in pain management to “complementary medicine” approaches. It culminates in 7 key “Recommendations for Pain Management Research,” all targeted to identifying effective pain-management strategies, not just elimination of opioids. Among those recommendations are the following:

  • Define all terms (such as “long-term opioid use”) precisely.
  • Quantify opioid use in morphine milligram equivalents (MMEs), and state how MMEs were calculated.
  • Precisely define the study population (including age, sex, and socioeconomic and cultural characteristics).
  • Mental/emotional risk factors–including depression, catastrophizing, expectations, and coping ability–should be studied.
  • Outcome measures should be patient-related, not just the number of pills taken.

JBJS would again like to thank NIAMS for its support and all Symposium participants and Supplement authors for their time and energy.

Pain Management Symposium Focuses on Study Design

Designing studies to answer questions about surgical procedures takes a lot of thought, effort, and experience. Creating robust study designs to investigate pain management related to musculoskeletal conditions and procedures presents additional, unique challenges.

On November 19, 2019, more than 30 orthopaedic researchers and journal editors convened to identify—and propose solutions for—those challenges. The one-of-a-kind Pain Management Research Symposium was supported by a grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS award number 1R13AR076879-01) and hosted by The Journal of Bone & Joint Surgery.

Several themes emerged from the daylong discussions and presentations:

  • Despite the fact that 80% of opioid prescriptions worldwide originate in the US, outcome measures going forward should focus on effective pain management rather than reduced or “zero” opioids.
  • The wide variability of definitions of key research terms such as “opioid naïve” and “persistent opioid use” makes it difficult to reach robust conclusions from prior opioid/pain management research.
  • Beware false equations/assumptions. For example, opioid prescription filling is not the same as opioid consumption, and persistent opioid use after surgery does not equal iatrogenic opioid dependence.
  • Surgeons and other physicians must maintain a biopsychosocial perspective on pain management. Risk factors for persistent use of opioids include mental/emotional states such as depression and catastrophizing.
  • Despite some equivocal reports in the orthopaedic literature, there is no convincing evidence that NSAIDs negatively affect fracture healing. Therefore, absent specific patient contraindications, NSAIDs can be considered for pain management in trauma cases.

Many more details from the Pain Management Research Symposium will appear in a special JBJS supplement, scheduled for publication in the first half of 2020.

The Journal would again like to thank all the participants for their time and energy and NIAMS for its support.

What’s New in Orthopaedic Rehabilitation 2019

Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all such OrthoBuzz summaries.

This month, co-author Nitin B. Jain, MD, MSPH selected the most clinically compelling findings from the 40 studies summarized in the November 20, 2019 “What’s New in Orthopaedic Rehabilitation.

Pain Management
–A randomized controlled trial compared pain-related function, pain intensity, and adverse effects among 240 patients with chronic back, hip, or knee pain who were randomized to receive opioids or non-opioid medication.1 After 12 months, there were no between-group differences in pain-related function. Statistically, the pain intensity score was significantly lower in the non-opioid group, although the difference is probably not clinically meaningful. Adverse events were significantly more frequent in the opioid group.

–A series of nested case-control studies found that the use of the NSAID diclofenac was associated with an increase in the risk of myocardial infarction in patients with spondyloarthritis and osteoarthritis, relative to those taking the NSAID naproxen.2

–Intra-articular injections of corticosteroids or hyaluronic acid are often used for pain relief prior to an eventual total knee arthroplasty (TKA). An analysis of insurance data found that patients who had either type of injection within three months of a TKA had a higher risk of periprosthetic joint infection (PJI) after the operation than those who had injections >3 months prior to TKA.

Partial-Thickness Rotator Cuff Tears
–A randomized controlled trial of 78 patients with a partial-thickness rotator cuff compared outcomes of those who underwent immediate arthroscopic repair with outcomes among those who delayed operative repair until completing 6 months of nonoperative treatment, which included activity modification, PT, corticosteroid injections, and NSAIDs.3 At 2 and 12 months post-repair, both groups demonstrated improved function relative to initial evaluations. At the final follow-up, there were no significant between-group differences in range of motion, VAS, Constant score, or ASES score. Ten (29.4%) of the patients in the delayed group dropped out of the study due to symptom improvement.

Stem Cell Therapy
–A systematic review that assessed 46 studies investigating stem cell therapy for articular cartilage repair4 found low mean methodology scores, indicating overall poor-quality research. Only 1 of the 46 studies was classified as excellent, prompting the authors to conclude that evidence to support the use of stem cell therapy for cartilage repair is limited by a lack of high-quality studies and heterogeneity in the cell lines studied.

References

  1. Krebs EE, Gravely A, Nugent S, Jensen AC, DeRonne B, Goldsmith ES, Kroenke K, Bair MJ, Noorbaloochi S. Effect of opioid vs nonopioid medications on pain-related function in patients with chronic back pain or hip or knee osteoarthritis pain: the SPACE randomized clinical trial. JAMA. 2018 Mar 6;319(9):872-82.
  2. Dubreuil M, Louie-Gao Q, Peloquin CE, Choi HK, Zhang Y, Neogi T. Risk ofcmyocardial infarction with use of selected non-steroidal anti-inflammatory drugs incpatients with spondyloarthritis and osteoarthritis. Ann Rheum Dis. 2018 Aug;77(8): 1137-42. Epub 2018 Apr 19.
  3. Kim YS, Lee HJ, Kim JH, Noh DY. When should we repair partial-thickness rotator cuff tears? Outcome comparison between immediate surgical repair versus delayed repair after 6-month period of nonsurgical treatment. Am J Sports Med. 2018 Apr;46(5):1091-6. Epub 2018 Mar 5.
  4. Park YB, Ha CW, Rhim JH, Lee HJ. Stem cell therapy for articular cartilage repair: review of the entity of cell populations used and the result of the clinical application of each entity. Am J Sports Med. 2018 Aug;46(10):2540-52. Epub 2017 Oct 12.

Eschew the “Quick Fix” Approach to Early Knee OA

OrthoBuzz occasionally receives posts from guest bloggers. In response to a recent study in Arthritis Care & Researchthe following commentary comes from Jeffrey B. Stambough, MD.

As orthopaedic surgeons, we share a collective objective to help patients improve function while minimizing pain. When patients come to our office for a new clinical visit for knee osteoarthritis (OA), we spend time getting to know them and gathering information about their activities, limitations, and functional goals. We balance this patient-reported information with discrete data points, such as weight, range-of-motion restrictions, and radiographic disease classification. Based on the symptom duration and other factors, most patients are not candidates for a knee replacement at this first visit. However, despite the publication of clinical practice guidelines for the nonoperative management of knee OA in 2008, with an update in 2013, significant variation exists in how orthopaedists treat these patients.

This guideline–practice disconnect is emphasized in findings from a recent study in Arthritis Care & Research that examined nonoperative knee OA management practices during clinic visits between 2007 and 2015. The authors found that the overall prescription of NSAID and opioid medications increased 2- and 3-fold, respectively, over that time, while recommendations for lifestyle interventions, self-directed activity, and physical therapy decreased by about 50%.

To me, the most troubling finding from this study is the sharp increase in narcotic prescriptions, because recent evidence demonstrates that narcotics do not effectively treat arthritis pain. Moreover, for patients who go on to arthroplasty, recent studies have found that preoperative opioid use portends worse postsurgical outcomes in terms of higher revision rates,  worse function scores, and decreased knee motion.

The findings from this study also speak to a larger societal issue for doctors and patients alike: the desire for a “quick fix.”  Despite the time pressure from increasing EHR documentation burdens, dwindling reimbursements, or lack of local resources, we owe it to our patients to counsel them on lifestyle modifications and self-management strategies to help them stay mobile, lose weight (if necessary), and take charge of their joint health. As orthopaedic surgeons, we must continue to strive to de-emphasize opioid pain medication when treating knee OA patients and support them in a holistic manner to ensure their overall health and the function and longevity of their native knee joint.

Jeffrey B. Stambough, MD is an orthopaedic hip and knee surgeon, an assistant professor of orthopaedic surgery at University of Arkansas for Medical Sciences, and a member of the JBJS Social Media Advisory Board.

What’s New in Hip Replacement 2019

Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries. This month, Mengnai Li, MD, co-author of the September 18, 2019 “What’s New in Hip Replacement,” selected the five most clinically compelling findings from among the more than 100 studies summarized in the article.

THA Dislocation
–Pathology involving the spinopelvic relationship has dominated the recent literature on THA dislocation. For patients presenting with a flatback deformity and stiff spine, who had the highest risk of dislocation, the authors of a recent study suggested the use of a dual-mobility implant construct with targeted 30° of anteversion relative to the functional pelvic plane, based on a standing anteroposterior radiograph.1

Preferred Implant Designs
–A study comparing data from the American Joint Replacement Registry with national registry data from other countries found that cementless stem fixation with the use of ceramic and 36-mm heads was the current US preference, while non-US registries indicated that cemented implants and metal and 32-mm heads were used most commonly.2

Opioid Use
–The ongoing effort in the orthopaedic community to reduce opioid consumption without compromising quality of life for joint-replacement patients may be aided by findings from a recent randomized controlled trial. The study found that prescribing 30 immediate-release oxycodone pills instead of 90 pills was associated with a significant reduction in unused pills and decreased opioid consumption without affecting pain scores and patient-reported outcomes.3

Penicillin Allergy
– A retrospective review of >4,900 patients who underwent THA or TKA found that 16.2% reported a history of penicillin allergy. No patients among those with a stated penicillin allergy who were given cefazolin had an adverse reaction. Also, there was no increased rate of surgical site infections among those with a stated penicillin allergy who received clindamycin or vancomycin, although the authors acknowledged that this part of the study was underpowered due to the low overall rate of infection.4

Use of TXA
–Recent guidelines on the use of tranexamic acid (TXA) state that no specific routes of administration, dosage, dosing regimen, or time of administration have been shown to provide clearly superior blood-sparing properties.5

References

  1. Luthringer TA, Vigdorchik JM. A preoperative workup of a “hip-spine” total hip arthroplasty patient: a simplified approach to a complex problem. J Arthroplasty.2019 Jan 18. [Epub ahead of print].
  2. Heckmann N, Ihn H, Stefl M, Etkin CD, Springer BD, Berry DJ, Lieberman JR. Early results from the American Joint Replacement Registry: a comparison with other national registries. J Arthroplasty.2019 Jan 5.
  3. Hannon CP, Calkins TE, Li J, Culvern C, Darrith B, Nam D, Gerlinger TL, Buvanendran A, Della Valle CJ. The James A. Rand Young Investigator’s Award: large opioid prescriptions are unnecessary after total joint arthroplasty: a randomized controlled trial. J Arthroplasty.2019 Feb 4. [Epub ahead of print].
  4. Stone AH, Kelmer G, MacDonald JH, Clance MR, King PJ. The impact of patient-reported penicillin allergy on risk for surgical site infection in total joint arthroplasty. J Am Acad Orthop Surg.2019 Feb 27. [Epub ahead of print].
  5. Fillingham YA, Ramkumar DB, Jevsevar DS, Yates AJ, Bini SA, Clarke HD, Schemitsch E, Johnson RL, Memtsoudis SG, Sayeed SA, Sah AP, Della Valle CJ. Tranexamic acid use in total joint arthroplasty: the clinical practice guidelines endorsed by the American Association of Hip and Knee Surgeons, American Society of Regional Anesthesia and Pain Medicine, American Academy of Orthopaedic Surgeons, Hip Society, and Knee Society. J Arthroplasty.2018 Oct;33(10):3065-9. Epub 2018 Aug 7.

Who’s at Risk for Prolonged Opioid Use after THA?

Much has been written in recent years about the orthopaedist’s predilection for prescribing opioids, most of which has been aimed at helping us become better stewards of these medications. It is imperative that we continue learning how best to prescribe opioids to maximize their effectiveness in postoperative pain management, while minimizing their many harmful and potentially lethal effects. With some patients, finding that balance is much easier than with others. Learning to identify which patients may struggle with achieving that equilibrium is one way to address the current opioid epidemic.

In the September 18, 2019 issue of The Journal, Prentice et al. identify preoperative risk factors that are associated with prolonged opioid utilization after total hip arthroplasty (THA) by retrospectively evaluating the number of opioid prescriptions dispensed to >12,500 THA patients. Many of the findings are in line with those of previous studies looking at this question. Prentice et al. found that the following factors were associated with greater opioid use during the first postoperative year:

  • Preoperative opioid use
  • Female sex
  • Black race
  • Anxiety
  • Higher BMI
  • Substance abuse
  • Back pain
  • AIDS
  • Chronic pulmonary disease

For me, the most noteworthy finding was that almost 25% of all patients in the study were still using opioids 271 to 360 days after their operation. That is a much higher percentage than I would have guessed prior to reading this study. Somewhat less surprising but also concerning was the finding that 63% of these patients filled at least 1 opioid prescription in the year prior to their THA, leading the authors to suggest that orthopaedic surgeons “refrain from prescribing opioids preoperatively” or “decrease current opioid users’ preoperative doses.”

Although some readers may be suffering from “opioid fatigue” in the orthopaedic literature, I encourage our community to  continue addressing our role in the current opioid crisis. While I believe that we have changed our prescribing practices since the data for this study were collected (2008 through 2011), we cannot dismiss these findings. The opioid epidemic is multifactorial and has many deep-rooted tendrils in our healthcare system. We owe it to our patients and to the public at large to be as significant a part of the solution as possible.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media

Why US Orthopaedic Residents Overprescribe Opiates

Hydrocodone Has Dark Side as Recreational DrugSeveral authors have described the medical-school experience as “socialization” into the medical field. Medical students often learn the scientific underpinnings simultaneously with the social processes of interviewing/dialoging, examining, and then developing a treatment plan with the patient. One “subspecialty” social process that orthopaedists learn is pain management. While we are certainly encouraged to understand the scientific basis of this important and complex topic, much of the learning comes in the form of mirroring: junior residents do what senior residents instruct them to do, while senior residents follow the direction of attendings. These passed-on habits are culturally ingrained and persistent.

As Young et al. show in the July 17, 2019 issue of The Journal, the pain-management habits learned in training vary greatly from country to country, which is not surprising. Specifically, these authors examined the prescribing of postprocedural opiates by residents in the Netherlands, Haiti, and United States. They found that US residents prescribe significantly more morphine milligram equivalents (MMEs) of opioids at patient discharge than residents from either of the other 2 countries. The authors also showed that residents from the United States were the only group prescribing a significantly greater amount of MMEs to patients younger than 40 years old than to those above the age of 70.

Many pundits pin the phenomenon of opioid overprescribing in the US on the American public’s wish to be free from discomfort, along with the aggressive marketing and advertising of these medications in the United States. While this may be true, I think Young et al. have further identified the major influence that a resident’s training environment may have on prescribing practices. As already mentioned, residents often imitate what they see from more experienced residents and attendings, but sometimes those lessons, especially in pain management, lack a scientific basis.

What is missing from this survey-based study is data on patient satisfaction with postprocedural opiate prescribing. Having been involved in clinical care in Haiti, my impression is that patients there accept the local practice of pain management, constrained as it might be by resource limitations. I suspect the same is true in the United States and the Netherlands. Regardless, these findings demand that emphasis be placed on teaching orthopaedic residents evidence-based pain-management protocols. This will require a concerted effort from teachers and mentors at all levels of our medical-education system. This investigation is an important reminder that developing solutions to the opioid overprescribing problem in the US might begin in residency, where “cultural formation” occurs.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

What’s New in Spine Surgery 2019

Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries. This month, Jacob M. Buchowski, MD, MS, coauthor of the June 19, 2019 What’s New in Spine Surgery,” selected the five most clinically compelling findings from among the 47 noteworthy studies summarized in the article.

Predictive Analytics for Deformity Conditions
–A validated model for predicting outcomes after lumbar spine surgery1 found that patients with lower preoperative disability scores, those covered by Medicaid or Workers’ Compensation, and current and previous smokers were less likely to improve with lumbar fusion surgery. Invasiveness of surgery and surgeon and hospital type had lower predictive value.

Early-Onset Scoliosis (EOS)
–A 5-year direct-cost estimate2 comparing magnetic growing rods and conventional growing rods for the treatment of EOS found the total cost for magnetic growing rods to be £34,741 compared with £52,293 for conventional growing rods.

Pediatric Neuromuscular Scoliosis
–A Level-II study investigated patient factors associated with postoperative pulmonary complications among patients with neuromuscular scoliosis who underwent posterior spinal fusion.3 Patients with a history of pneumonia or gastrotomy tube at the time of surgery had an elevated risk of postoperative respiratory infections.

Opioid Consumption
–Findings from a retrospective study of >27,000 patients who underwent lumbar decompression with or without fusion revealed that the majority of patients using prescription opioids discontinued those medications postoperatively. However, among the patients with opioid use >90 days after surgery, the duration of preoperative opioid use was the most important predictor of postoperative opioid use.

Neurological Decline after Adult Spinal Deformity Surgery
–In a retrospective analysis of 265 patients who underwent corrective surgery for adult spinal deformity,4 23% of patients experienced a neurological injury; among those, 33% experienced a major neurological decline. Among the patients with major decline, full recovery was observed in 24% at 6 weeks and 65% at 6 months, but one-third of those patients experienced persistent neurological deficits at 24 months postoperatively. Among patients who experienced a minor neurological injury, 49% reported full recovery at 6 weeks and 70% reported full recovery at 6 months. About one-quarter of those patients showed no improvement at 24 months.

References

  1. Khor S, Lavallee D, Cizik AM, Bellabarba C, Chapman JR, Howe CR, Lu D, Mohit AA, Oskouian RJ, Roh JR, Shonnard N,Dagal A, Flum DR. Development and validation of a prediction model for pain and functional outcomes after lumbar spine surgery. JAMA Surg.2018 Jul 1;153(7):634-42.
  2. Harshavardhana NS, Noordeen MHH, Dormans JP. Cost analysis of magnet-driven growing rods for early-onset scoliosis at 5 years. Spine (Phila Pa 1976).2019 Jan 1;44(1):60-7.
  3. Luhmann SJ, Furdock R. Preoperative variables associated with respiratory complications after pediatric neuromuscular spine deformity surgery. Spine Deform.2019 Jan;7(1):107-11.
  4. Kato S, Fehlings MG, Lewis SJ, Lenke LG, Shaffrey CI, Cheung KMC, Carreon LY, Dekutoski MB, Schwab FJ, Boachie-Adjei O, Kebaish KM, Ames CP, Qiu Y, Matsuyama Y, Dahl BT, Mehdian H, Pellisé F, Berven SH. An analysis of the incidence and outcomes of major versus minor neurological decline after complex adult spinal deformity surgery: a subanalysis of Scoli-RISK-1 study. Spine (Phila Pa 1976).2018 Jul 1;43(13):905-12.