Nicholas U Ahn

Case Western Reserve University | CWRU · Department of Orthopaedics (University Hospitals Case Medical Center)

Study Design Level III evidence—retrospective cohort. Objective The purpose of this study was to (1) determine whether longer CDA operative time increases the risk of 30-day postoperative complications, (2) analyze the association between operative time and subsequent health care utilization, and (3) discharge disposition. Background Cervical dis...

Study Design Retrospective cohort study. Objectives The study aimed to (1) compare baseline demographics of patients undergoing surgery for SEA who were/were not readmitted; (2) identify risk factors for 90-day readmissions; and (3) quantify 90-day episode-of-care health care costs. Background Spinal epidural abscess (SEA), while rare, occurring...

Study Design Retrospective cohort study. Objective The purpose of this study is to compare the impact of anterior cervical decompression and fusion (ACDF) versus posterior cervical decompression and fusion (PCDF) for the treatment of acute traumatic central cord syndrome (CCS) on hospital episodes of care in terms of (1) cost, (2) length of hospit...

Study Design Retrospective cohort study Objective To compare elective single-level anterior cervical discectomy and fusion (ACDF) versus posterior cervical decompression and fusion (PCDF) for degenerative cervical myelopathy (DCM) in terms of (1) cost, (2) length of hospital stay, and (3) discharge destination in Medicare patients. A sub-analysis...

Introduction Hypercholesterolemia is known to be a major contributor to the morbidity associated with cardiovascular disease and has been hypothesized to result in degenerative changes to the spine through atherosclerosis of segmental lumbar vessels. The purpose of this study is to determine the relationship between hypercholesterolemia and degener...

Hematoma after anterior cervical spine surgery can result in neurologic and airway compromise. Current guidelines recommend an international normalized ratio (INR) <1.5 before elective spine surgery because of increased complications. The risk associated with an INR of 1.25 is not well studied. The purpose of this study was to determine the risk of...

Study design: Retrospective Case-Control Study. Objectives: The objectives were to determine whether patients from poor social determinants of health (SDOH), undergoing primary 1-2 level lumbar fusion (1-2LF), demonstrate differences in: 1) medical complications; 2) emergency department (ED) utilizations; 3) readmission rates; and 4) costs of ca...

Introduction: With the advent of bundled care payments for spine surgery, there is increasing scrutiny on the costs and resource utilization associated with surgical care. The purpose of this study was to compare (1) the total cost of the hospital episode of care and (2) discharge destination between White, Black, and Hispanic patients receiving e...

Study design: Retrospective cross-sectional analysis. Summary of background data: Degenerative changes are a major contributor to chronic neck pain. According to the vascular hypothesis of disc disease, atherosclerosis of the segmental arteries contributes to ischemia of the lumbar discs and resulting degenerative changes. Prior studies have dem...

Study Design Retrospective Cohort Study Objective Cervical radiculopathy meeting operative criteria has traditionally been managed using anterior cervical discectomy and fusion (ACDF). However, cervical disc arthroplasty (CDA) and posterior cervical foraminotomy (PCF) are also reasonable options. This study aimed to assess differences in postopera...

BACKGROUND CONTEXT The development of a postoperative epidural hematoma following lumbar spinal stenosis surgery is an uncommon but potentially devastating complication. It is unclear of the long-term clinical and economic impact related to the additional surgical care needed to treat these adverse events. PURPOSE To define the incidence of acute...

BACKGROUND CONTEXT The majority of cervical radiculopathy patients, an estimated 75 to 90%, improve with nonoperative management. Nevertheless, patients refractory to nonoperative treatment for six weeks or those experiencing concerning signs/symptoms (progressive and significant neurologic deficits) are operative candidates. Anterior cervical disc...

BACKGROUND CONTEXT Acute postoperative surgical site infections (SSI) following instrumented lumbar spine fusions are a relatively infrequent occurrence. Treatment of an SSI with prompt surgical debridement and prolonged, parenteral antibiotics is generally effective and most often results in eradication of the infection and maintenance of the inst...

BACKGROUND CONTEXT Degenerative cervical myelopathy (DCM) represents a collection of age-related degenerative processes of the cervical spine that can result in motor, sensory and autonomic dysfunction, leading to significant reductions in quality of life. Older individuals, and in particular octogenarians, with advanced myelopathy pose unique clin...

BACKGROUND CONTEXT With ever-rising health care costs, the value of surgical interventions should be evaluated closely. Degenerative spondylotic cervical myelopathy (DSCM) is a debilitating condition with surgical intervention being a widely accepted form of treatment. Surgery can be performed in the form of either anterior cervical decompression a...

BACKGROUND CONTEXT Significant disparities exist in outcomes based on patient race and ethnicity following orthopedic procedures. However, the literature is scarce on the impact of race/ ethnicity on hospital resource utilization following elective anterior cervical discectomy and fusion (ACDF). PURPOSE The purpose of this study was to compare (1)...

BACKGROUND CONTEXT The COVID-19 pandemic has caused significant strain on the US health care system, with many hospitals struggling to provide resources for perioperative care and even necessitating the cessation of elective surgery for periods of time. Therefore, it is imperative to understand the hospital resource demands of elective surgery and...

Purpose Most randomized trials comparing open carpal tunnel release (OCTR) to endoscopic carpal tunnel release (ECTR) are not specific to a working population and focus mainly on how surgical technique has an impact on outcomes. This study’s primary goal was to evaluate factors affecting days out of work (DOOW) following carpal tunnel release (CTR)...

The objective of this study was to determine the impact of smoking on clinical outcomes in workers' compensation (WC) patients receiving spinal cord stimulation (SCS). One hundred and ninety-six patients from the Ohio Bureau of Workers' Compensation were identified who received SCS with implantation occurring between 2007-2012. Patients were divide...

BACKGROUND CONTEXT Acute postoperative surgical site infections (SSI) following instrumented lumbar spine fusions are a relatively infrequent occurrence. Treatment of an SSI with prompt and aggressive surgical debridement along with prolonged postoperative parenteral antibiotics is generally effective and most often results in eradication of the in...

BACKGROUND CONTEXT Incidental durotomies (ID) are a known occurrence in lumbar spine surgery. In most cases, an ID can be effectively managed with direct repair that is often supplemented by fibrin glue or a synthetic or biologic patch. Generally, there is minimal adverse effect to the patient other than a longer than expected postoperative hospita...

Study design: This was a retrospective cross-sectional analysis. Objective: The objective of this study was to estimate the incremental health care costs of depression in patients with spine pathology and offer insight into the drivers behind the increased cost burden. Summary of background data: Low back pain is estimated to cost over $100 bi...

The optimal timing of lumbar diskectomy in patients with lumbar disk herniation and radiculopathy has not been studied in the workers' compensation (WC) population. A total of 10,592 patients received lost-work compensation from the Ohio Bureau of Workers' Compensation for a lumbar disk herniation between 2005 and 2012. The primary outcome was whet...

Although various studies have proposed vascular and mechanical factors, the etiology of Kienböck disease is unknown. Kienböck theorized that lunatomalacia resulted from traumatic disruption of blood supply and bony nutrition to the lunate. Extraosseous supply to the lunate, as far as volar or dorsal vessels are concerned, is still controversial. Th...

BACKGROUND CONTEXT Acute postoperative surgical site infections (SSI) following instrumented lumbar fusions are a relatively infrequent occurrence. Treatment with aggressive surgical debridement and parenteral antibiotics are generally effective in leading to eradication of infection and maintenance of the instrumentation. However, it is not clear...

BACKGROUND CONTEXT Studies have stressed the importance of timely surgical intervention for patients with cauda equina syndrome (CES); however, studies investigating outcomes between acute (within 48-hours) and delayed (after 48 hours) surgical intervention following CES while controlling for multiple confounders are limited. PURPOSE The purpose o...

BACKGROUND CONTEXT Decompressive surgery for symptomatic lumbar spinal stenosis is predictable and effective in providing relief of radiculopathy and neurogenic claudication. Decompression alone, without fusion, is generally reserved for patients with preserved lordosis and no evidence of instability. On occasion, spinal deformity and instability c...

Diabetes currently affects over 25 million Americans, with the elderly carrying much of the disease burden. It's well known that diabetes increases the risk of surgical complications, but few studies have analyzed its effects on reoperation rates after single-level lumbar discectomy. Data was obtained using the commercially available Explorys softw...

The purpose of this study was to examine the relationship between smoking and back pain in a cross-sectional analysis. Using the Osteoarthritis Initiative database, a multi-center, longitudinal, observational cohort study with 4796 participants, we examined the prevalence of back pain and of limitations in activity due to back pain, as well as the...

Removal of a herniated disk that is causing neural compression is among the most common indications for spinal surgery. Previous population database studies of risk factors for reoperation after this procedure analyzed small to medium numbers of patients. To date, no study has concurrently assessed the effect of modifiable risk factors, such as smo...

Background Optimal surgical management of displaced femoral neck fractures (dFNFs) in subjects 45-65 years old is unclear. We evaluated days out of work(dOOW), medical and indemnity costs, and secondary outcomes at 2 years between internal fixation(IF), hemiarthroplasty(HA), and total hip arthroplasty(THA) among workers’ compensation (WC) subjects...

The prevalence of obesity has been rising, creating a major public health concern. While several studies have shown obesity to increase the risk of surgical complications, few have analyzed its effects on reoperation, specifically after singlelevel lumbar discectomy. Data was obtained using the commercially available Explorys software that houses d...

This study sought to determine the impact of time to surgery on clinical outcomes in patients with spondylolisthesis in the workers' compensation (WC) population. There is conflicting evidence regarding the effect of time to surgery on patients with spondylolisthesis. Patients receiving WC are known to have worse outcomes following spine surgery co...

Background The incidence of hip fractures continues to grow due in part to an aging population and increasing activity levels. With the potential implementation of bundled-care payment models for the operative fixation of hip fractures, a metric that accurately predicts postoperative length of stay and adverse events would allow for adjustments in...

Background Symptomatic post-operative lumbar epidural hematoma (PLEH) is a complication of lumbar spine surgery that can cause permanent neurologic consequences through compression of the cauda equina and nerve roots. Questions/Purposes We sought to investigate the incidence, timing, and risk factors for symptomatic epidural hematomas following po...

Study design: Retrospective case-control study. Objective: To determine incidence and timing of mortality following surgery for spinal epidural abscess (SEA), identify risk factors for mortality, and identify complications associated with mortality. Summary of background data: SEA is a serious condition with potentially devastating sequelae. T...

Cervical myelopathy is the most common cause of acquired spinal cord dysfunction in people aged >55 years. Advanced age and duration of symptoms have been implicated in the literature as negative prognostic indicators for postoperative functional improvement, but very few studies have evaluated the interaction of these factors. We retrospectively r...

BACKGROUND CONTEXT Patients with workers’ compensation (WC) undergoing cervical surgery have been shown to have inferior outcomes compared with the general population. Previous studies have suggested that the reason behind this discrepancy is multifactorial. Within this clinically distinct population, the ability to return to work (RTW) is particul...

Pedicle screws are a common treatment option for spinal instability. Despite their popularity, pedicle screws carry the risk of transpedicular violation with subsequent neural and vascular damage. This study measured the pedicle dimensions of 500 dry specimens in an osteological collection. The data provide the orthopedic spine surgeon with an accu...

Lumbar discography (LD) is used to guide surgical decision making in patients with degenerative disc disease (DDD). Its safety and diagnostic accuracy are under contention. This study evaluates LD's efficacy within the workers' compensation (WC) population. Multivariate logistic regression analysis was used to determine the impact that undergoing L...

Study design: Cross-sectional study. Objective: To determine whether there is an association between body mass index (BMI) and the prevalence, severity, and frequency of low back pain and identify other potential patient risk factors for the development of low back pain. Summary of background data: Many studies have implicated that a high BMI...

INTRODUCTION Opiates are commonly used for the initial treatment of degenerative lumbar stenosis (DLS). However, current evidence suggests that overuse of opioids may alter pain-modulatory systems and increase pain sensitivity, which may worsen the underlying condition. As such, patients undergoing operative treatment for DLS with concomitant opioi...

Study design: Retrospective Cohort Study. Objective: The objective of this study is to determine how time to surgery affects outcomes for degenerative lumbar stenosis (DLS) in a workers' compensation (WC) setting. Summary of background data: WC subjects are known to be a clinically distinct population with variable outcomes following lumbar su...

Study design: Retrospective cohort. Objective: Determine the impact of preoperative opioid use in workers' compensation (WC) patients undergoing lumbar diskectomy (LD). Summary of background data: The prevalence of back pain among opioid users approached 60%. Long term opioid dependence in spine surgery patients is roughly 20%. Despite pervasi...

Study design: Retrospective cohort study. Objective: To determine outcomes after reoperation discectomy with or without fusion surgery for recurrent lumbar disc herniation (RLDH) in the workers' compensation (WC) population. Summary of background data: RLDH is estimated to occur in 7% to 24% of patients after discectomy. There are two main sur...

Study design: Retrospective comparative case-control study. Objectives: The objectives of this study are: (1) How preoperative opioid use impacts RTW status after single-level cervical fusion for radiculopathy? and (2) What are other postsurgical outcomes affected by preoperative opioid use? Summary of background data: Opioid use has increased...

Study design: Retrospective cohort comparative study. Objective: To evaluate presurgical and surgical factors that affect return to work (RTW) status after multilevel cervical fusion, and to compare outcomes after multilevel cervical fusion for degenerative disc disease (DDD) versus radiculopathy. Summary of background data: Cervical fusion pr...

Study design: Retrospective cohort study OBJECTIVE.: To investigate the impact of prolonged opioid use in the preoperative treatment plan of degenerative lumbar stenosis (DLS) SUMMARY OF BACKGROUND DATA.: Patients undergoing operative treatment for DLS with concomitant opioid use represent a clinically challenging population. The relative paucity...

Study design: Retrospective cohort study OBJECTIVE.: Analyze efficacy of vertebroplasty and its affect on return to work (RTW) in a workers' compensation (WC) population SUMMARY OF BACKGROUND DATA.: Vertebroplasty remains a controversial treatment modality for vertebral compression fractures (VCFs). No studies have analyzed use of vertebroplasty i...

Study design: Retrospective cohort study. Objective: To compare outcomes in Workers' compensation (WC) subjects receiving decompression alone versus decompression and fusion for the indication of degenerative spinal stenosis (DLS) without deformity or instability. Summary of background data: The use of a fusion procedure during lumbar decompre...

The use of opioids among patients with workers' compensation claims is associated with tremendous costs, especially for patients who undergo spinal surgery. This study compared return-to-work rates after single-level cervical fusion for degenerative disk disease between patients who received opioids before surgery and patients who underwent fusion...

This study examined the effect of bilateral and unilateral L5 pars defects on the degree of disk degeneration at the L5-S1 level in cadaveric specimens. An observational study was performed of 690 cadaveric specimens selected at random. These specimens represent individuals who died between 1893 and 1938. The study included 558 male and 132 female...

Surgical models have best shown the relationship between ankle and mid-foot osteoarthritis, although findings regarding the calcaneocuboid joint have varied. To the authors' knowledge, no studies have evaluated the relationship between degenerative changes across the tibiotalar and calcaneocuboid joints. The goal of this study was to determine whet...

Study design: A retrospective comparative cohort study. Objective: To compare return to work (RTW) rates for patients who underwent single-level cervical fusion for radiculopathy compared with fusion for degenerative disc disease (DDD) as an indication for surgery. Summary of background data: Studies have shown that workers' compensation subje...

Classically, it is thought that pain or disability in one leg can stress the contralateral leg, leading to similar symptoms. The mechanism of action for subsequent dysfunction in the healthy limb is thought to involve compensatory changes that are used as a means to reduce stance phase time on the injured limb. This is believed to increase the forc...

Study design: Retrospective comparative cohort study. Objective: Examine the impact of prolonged preoperative opioid use on return to work status after single-level cervical fusion for radiculopathy. Summary of background data: The use of opioids has a dramatic impact in a workers' compensation population. The costs of claims that involved opi...

There are conflicting reports regarding postoperative bleeding risks associated with discontinuation of antiplatelet therapy at least 7 days preoperatively. Most of the studies in the spine literature are based on surveys or anecdotal evidence. The majority of surgeons discontinue therapy 7 days preoperatively, but this varies widely from 5 to 21 d...

Study design: Retrospective Cohort OBJECTIVE.: This study investigates the interplay between duration of preoperative symptoms and smoking status with respect to postoperative outcomes in patients with cervical spondylotic myelopathy (CSM). Summary of background data: Many studies have established the harms of smoking and several have identified...

Study design: Retrospective Cohort. Objective: The objective of the study was to determine what effect, if any, diabetes has on surgical outcomes in patients with Cervical Spondylotic Myelopathy. Summary of background data: Diabetes is known to impair healing and has been shown to affect outcomes in lumbar surgery, but few studies have assesse...

Lumbar fusion for spondylolisthesis is associated with consistent outcomes in the general population. However, workers' compensation is a risk factor for worse outcomes. Few studies have evaluated prognostic factors within this clinically distinct population. The goal of this study was to identify prognostic factors for return to work among patient...

Background: Little is known about the association between smoking and intraoperative blood loss and perioperative transfusion use in patients undergoing spinal surgery. However, we found that although many of the common complications and deleterious effects of smoking on surgical patients had been well documented, the aspect of blood loss seemingl...

Lumbar fusion for degenerative disk disease (DDD) is associated with variable clinical outcomes. Patients with workers’ compensation claims often have worse fusion outcomes than the general population. Few studies have evaluated the risk factors for poor outcomes within this clinically distinct population. The goal of this study was to identify pre...

Lumbar diskography (LD) is frequently used in the evaluation of patients with degenerative disk disease and diskogenic low back pain. Its safety and diagnostic accuracy are a topic of debate. No study has evaluated the efficacy of LD within the clinically distinct workers' compensation population. Within this setting, the authors wished to determin...

Study Design A retrospective comparative cohort study. Objective To compare return to work (RTW) rates for patients who underwent single-level cervical fusion for radiculopathy compared with fusion for degenerative disc disease (DDD) as an indication for surgery. Summary of Background Data Studies have shown that workers’ compensation subjects ha...

Background: Cadaveric studies have examined disc degeneration at the L4-L5 and L5-S1 motion segments; however, we are not aware of another study that has examined the relationship between bilateral spondylolysis and its effect on degenerative disc disease at those levels. This may have been overlooked by researchers owing to the majority of spondy...

Study Design. An anatomic study of pedicle dimensions was performed for lumbar vertebrae from American subjects. To quantify the dimensions of the lumbar pedicles and to better define the demographic factors that could ultimately govern the caliber selection of pedicle screws. Transpedicular screw fixation allows for segmental instrumentation into...

Retrospective cohort studyObjective. Evaluate prescription opioid utilization after lumbar fusion for degenerative disc disease (DDD) in a workers' compensation (WC) settingSummary of Background Data. Use of opioids for treating chronic low-back pain has increased greatly. Few studies have evaluated risk factors for chronic opioid therapy (COT) amo...

Study design: Retrospective cohort. Objective: The purpose of this study was to compare outcomes of surgical treatment of cervical myelopathy between smokers and nonsmokers as assessed by the Nurick score. Summary of background data: The harmful effects of smoking on healing have been well established. However, the effect of smoking on postope...

Retrospective cohort study. Determine how psychosocial factors, particularly depression, impact lumbar fusion outcomes in a workers' compensation (WC) setting. WC patients are less likely to return to work (RTW) after fusion. Few studies evaluate risk factors within this clinically distinct population. A total of 2799 Ohio WC subjects were identifi...

Research has associated lumbar spinal disease with lower extremity arthrosis. These studies focused solely on the lumbar spine's connection with hip or knee pathology, failing to investigate potential ankle relationships. We specifically explored the interplay between lumbar disc degeneration and tibiotalar joint arthritis. Lumbar disc degeneration...

Study design: An anatomic study of pedicle dimensions was performed for lower thoracic vertebrae from American human subjects. Objective: To quantify the dimensions of the lower thoracic pedicles and to better define the demographic factors that could ultimately govern the caliber selection of pedicle screws. Summary of background data: Transp...

Study Design: Retrospective cohort study Objective: Compare lumbar fusion outcomes, return to work (RTW) status in particular, between workers’ compensation (WC) subjects undergoing single level posterolateral fusion for either spondylolisthesis or degenerative disc disease (DDD) Summary of Background Data: Lumbar fusion for spondylolisthesis ten...

Background Context The internet is frequently used by patients to aid in medical decision-making. Multiple studies display the internet’s ineffectiveness in presenting high quality information regarding surgical procedures and devices. With recent reports of unacceptably high complication rates and poor outcomes with the X-Stop device, it is import...

Study design: An anatomic study of pedicle dimensions was performed for upper thoracic vertebrae from American human subjects. Objective: To quantify the dimensions of the upper thoracic pedicles and to better define the demographic factors that could ultimately govern the caliber selection of pedicle screws. Summary of background data: Transp...

Studies of the quality and accuracy of health and medical information available on the Internet have shown that many sources provide inadequate information. However, to our knowledge, there are no published studies analyzing the quality of information available online regarding vertebroplasty. Because this has been a high-volume procedure with high...

Coxa magna, the asymmetrical circumferential enlargement of the femoral head, is an important sequela of pediatric disorders such as Legg-Calvé-Perthes disease. Definitions vary because of lack of controls and a scarcity of research on the distribution of the femoral head asymmetry. This study aims at defining the normal distribution of asymmetry b...

Nonorganic low back pain (NOLBP) is common in the worker's compensation (WC) population. Consults with specialists constitute an unnecessary cost to the system, and a means of screening for these patients is necessary. To design easily identifiable criteria to help identify which WC patients are likely to have nonorganic pain. A retrospective chart...

The use of oral anticoagulation therapy such as warfarin is projected to increase significantly as the population ages and the prevalence of cardiovascular disease increases. Current recommendations state that warfarin be discontinued before surgery and the international normalized ratio (INR) normalized. To determine if stopping warfarin 7 days be...