Applications of SPECT/CT in the Evaluation of Spinal Pathology: A Review.

BACKGROUND: Accurate identification of pain generators in the context of low back and spine-related pain is crucial for effective treatment. This review aims to evaluate the potential usefulness of single photon emission computed tomography with computed tomography (SPECT/CT) as an imaging modality in guiding clinical decision-making. METHODS: A broad scoping literature review was conducted to identify relevant studies evaluating the use of SPECT/CT in patients with spine-related pain. Studies were reviewed for their methodology and results. RESULTS: SPECT/CT appears to have advantages over traditional modalities, such as magnetic resonance imaging and CT, in certain clinical scenarios. It may offer additional information to clinicians and improve the specificity of diagnosis. However, further studies are needed to fully assess its diagnostic accuracy and clinical utility. CONCLUSIONS: SPECT/CT is a promising imaging modality in the evaluation of low back pain, particularly in cases where magnetic resonance imaging and CT are inconclusive or equivocal. However, the current level of evidence is limited, and additional research is needed to determine its overall clinical relevance. CLINICAL RELEVANCE: SPECT/CT may have a significant impact on clinical decision-making, particularly in cases in which traditional imaging modalities fail to provide a clear diagnosis. Its ability to improve specificity could lead to more targeted and effective treatment for patients with spinal pathology.

Metastatic mesenchymal chondrosarcoma of the spine managed with nonsurgical treatment: A case report and review of the literature.

In this report, we present a rare case of a 17-year-old male patient with metastatic mesenchymal chondrosarcoma (MCS) managed with nonsurgical treatment who subsequently demonstrated a favorable response to concurrent chemotherapy and radiation therapy, followed with pazopanib target therapy. Further study regarding nonoperative care for metastatic MCS of spine is warranted.

Preliminary Evaluation of Standing Full-Length Plain Radiographs Utility in an Adult Degenerative Spine Practice.

INTRODUCTION: The role of weight-bearing full-length standing radiographs (FLSRs) of the spine in the preoperative workup of adult degenerative disease of the lumbar spine is a subject of increasing research. This investigation aims to determine whether FLSR influences preoperative planning decisions. METHODS: In this prospective study, eight spine surgeons reviewed two 30-patient case series. The first set (set A) contained a patient history, physical examination data, and preoperative images. The second set (set B) contained all information in set A in addition to preoperative FLSR AP and lateral radiographs. Within 2 weeks of evaluating set A, reviewers assessed set B. Case sets were randomized. After reviewing each set, reviewers gave surgical plans and whether they believed an FLSR was important in planning. Decisions were evaluated by subspecialty, years of practice, and postfellowship years. A McNemar test assessed differences between set viewings. A chi-square test assessed differences of preoperative decision changes between different specialties and levels of experience. A Poisson regression assessed characteristics associated with changing preoperative plans. We analyzed patients by the number of unique reviewer procedures, surgical levels, and associated pathology. RESULTS: After viewing an FLSR, 44.7% of reviewers changed procedure. Reviewer opinion of FLSR importance differed between sets (27.1% versus 35.7%, P = 0.047). Among all reviewers, FLSR presentation was associated with aligning the number of proposed procedures in 15 patients. Scoliosis and sacral dysplasia were associated with negative deltas. FLSR viewing reduced the span of operational levels considered. Along the most divided patients, those with a high magnitude (≥6 choices) of initial procedures had more negative deltas than did those with a high number (≥5 choices) of surgical level choices. CONCLUSION: FLSR remains a critical aspect of presurgical planning. Even when reviewers initially believed patients would not benefit from FLSR, we observed changes in preoperative planning after FLSR viewing.

Visualization of the Cervicothoracic Junction With EOS Imaging Is Superior to Conventional Lateral Cervical Radiographs.

STUDY DESIGN: Single-center retrospective review. OBJECTIVES: The cervicothoracic junction (CTJ) is typically difficult to visualize using traditional radiographs. Whole-body stereoradiography (EOS) allows for imaging of the entire axial skeleton in a weightbearing position without parallax error and with lower radiation doses. In this study we sought to compare the visibility of the vertebra of the CTJ on lateral EOS images to that of conventional cervical lateral radiographs. METHODS: Two fellowship-trained spine surgeons evaluated the images of 50 patients who had both lateral cervical radiographs and EOS images acquired within a 12-month period. The number of visible cortices of the vertebral bodies of C6-T2 were scored 0-4. Patient body mass index and the presence of spondylolisthesis >2 mm at each level was recorded. The incidence of insufficient visibility to detect spondylolisthesis at each level was also calculated for both modalities. RESULTS: On average, there were more visible cortices with EOS versus XR at T1 and T2, whereas visible cortices were equal at C6 and C7. Patient body mass index was inversely correlated with cortical visibility on XR at T2 and on EOS at T1 and T2. There was a significant difference in the incidence of insufficient visibility to detect spondylolisthesis on EOS versus XR at C7-T1 and T1-2, but not at C6-7. CONCLUSIONS: EOS imaging is superior at imaging the vertebra of the CTJ. EOS imaging deserves further consideration as a diagnostic tool in the evaluation of patients with cervical deformity given its ability to produce high-quality images of the CTJ with less radiation exposure.

Patient Perceptions of Physician Ownership in Spine Care.

STUDY DESIGN: This was a prospective study. OBJECTIVE: This study aims to determine the perspectives of patients seeking spine care in regard to physician ownership of surgical facilities and to understand the importance of disclosing financial conflicts. SUMMARY OF BACKGROUND DATA: There has been limited investigation regarding patient perceptions of the proprietary structure of surgical facilities. METHODS: Patients seeking treatment for spine pathology completed an 8-item survey. The questions assessed if patients acknowledged the owners of surgical facilities, if the patient thought knowledge of ownership is important, who they perceived as most qualified to own surgical facilities, preference of communication of ownership, and impact of facility ownership on care. RESULTS: A total of 200 patients completed the survey. When patients were asked whom they thought owned the hospital, most reported private hospital corporations followed by universities/medical schools and insurance companies. With regard to whom patients thought owned an ambulatory surgical center, most reported physicians, followed by private hospital corporations and individual investors. When asked how important it is to know the financial stakeholders of a surgical facility, 73.5% of patients stated "very important" or "somewhat important." Most patients reported they were not aware of who owned the facility. Regarding how facility owners should be communicated, 31.0% answered "written document," whereas 25.0% preferred verbal communication with the staff/surgeon. When asked how much impact the owner of a surgical facility has on their care, 38.0% of patients responded, "strong impact," followed by "moderate impact," (43.0%), and "little or no impact" (19.0%). Patients thought that physicians were the most qualified to own an ambulatory surgical center, followed by universities/medical schools and private hospital corporations. CONCLUSIONS: The pretreatment perception of patients referred to a spine clinic favored the opinion that physicians were the most qualified to own and manage surgical facilities. Therefore, physicians should be encouraged to share disclosures with patients as their ownership of surgical facilities is viewed favorably.

Traumatic Fracture of the Pediatric Cervical Spine: Etiology, Epidemiology, Concurrent Injuries, and an Analysis of Perioperative Outcomes Using the Kids' Inpatient Database.

BACKGROUND: The study aimed to characterize trends in incidence, etiology, fracture types, surgical procedures, complications, and concurrent injuries associated with traumatic pediatric cervical fracture using a nationwide database. METHODS: The Kids' Inpatient Database (KID) was queried. Trauma cases from 2003 to 2012 were identified, and cervical fracture patients were isolated. Demographics, etiologies, fracture levels, procedures, complications, and concurrent injuries were assessed. The t-tests elucidated significance for continuous variables, and χ2 for categoric values. Logistic regressions identified predictors of spinal cord injury (SCI), surgery, any complication, and mortality. Level of significance was P < .05. RESULTS: A total of 11 196 fracture patients were isolated (age, 16.63 years; male, 65.7%; white, 65.4%; adolescent, 55.4%). Incidence significantly increased since 2003 (2003 vs 2012, 2.39% vs 3.12%, respectively), as did Charlson Comorbidity Index (CCI; 2003 vs 2012, 0.2012 vs 0.4408, respectively). Most common etiology was motor vehicle accidents (50.5%). Infants and children frequently fractured at C2 (closed: 43.1%, 32.9%); adolescents and young adults frequently fractured at C7 (closed: 23.9%, 26.5%). Upper cervical SCI was less common (5.8%) than lower cervical SCI (10.9%). Lower cervical unspecified-SCI, anterior cord syndrome, and other specified SCIs significantly decreased since 2003. Complications were common (acute respiratory distress syndrome, 7.8%; anemia, 6.7%; shock, 3.0%; and mortality, 4.2%), with bowel complications, cauda equina, anemia, and shock rates significantly increasing since 2003. Concurrent injuries were common (15.2% ribs; 14.4% skull; 7.1% pelvis) and have significantly increased since 2003. Predictors of SCI included sports injury and CCI. Predictors of surgery included falls, sports injuries, CCI, length of stay, and SCI. CCI, SCIs, and concurrent injuries were predictors of any complication and mortality, all (P < .001). CONCLUSIONS: Since 2003, incidence, complications, concurrent injuries, and fusions have increased. CCI, SCI, falls, and sports injuries were significant predictors of surgical intervention. Decreased mortality and SCI rates may indicate improving emergency medical services and management guidelines. LEVEL OF EVIDENCE: III. CLINICAL RELEVANCE: Clinicians should be aware of increased case complexity in the onset of added perioperative complications and concurrent injuries. Cervical fractures resultant of sports injuries should be scrutinized for concurrent SCIs.

Safety and Efficacy of Revision Minimally Invasive Lumbar Decompression in the Ambulatory Setting.

STUDY DESIGN: A retrospective analysis. OBJECTIVE: The aim of this study was to investigate differences in perioperative outcomes between patients undergoing revision minimally invasive lumbar spine decompression (MIS LD) in the ambulatory and hospital-based surgical settings. SUMMARY OF BACKGROUND DATA: Revision LD has been associated with an increased risk of complications compared with primary LD. Furthermore, ambulatory primary LD has been demonstrated to be a safe and viable option in appropriately selected patients. However, there is a paucity of information comparing hospital-based versus ambulatory outcomes in revision LD. METHODS: A prospectively maintained surgical registry of patients undergoing revision MIS lumbar laminectomy and/or discectomy for degenerative pathology from 2013 to 2017 was retrospectively reviewed. Propensity score matching was performed to adjust for measured confounding variables, including patient age, comorbidity burden as measured by Charlson Comorbidity Index, and preoperative diagnosis. Differences in operative variables, complication rates, pain scores, narcotics consumption, and reoperation rates were assessed using Pearson Chi-squared analysis (categorical) and Student t test (continuous). RESULTS: Seventy patients were included, of whom 35 underwent revision MIS LD at a hospital-based center (HBC), and 35 underwent surgery at an ambulatory surgical center (ASC). HBC and ASC patients demonstrated similar postoperative visual analog scale pain scores and hourly narcotics consumption during surgical stay (P < 0.001). ASC patients exhibited a significantly shorter length of stay than hospital-based patients (2.7 vs. 11.6 hours, P < 0.001). CONCLUSION: Patients undergoing revision MIS LD in an ASC demonstrated similar perioperative outcomes as compared to patients undergoing revision MIS LD in a HBC. These results suggest that revision MIS LD can be performed safe and effectively in the ambulatory setting in an appropriately selected surgical population. Further study of patient outcomes following spine surgery performed outside of the traditional hospital setting is crucial, as the delivery of care in the ambulatory setting continues to grow in popularity. LEVEL OF EVIDENCE: 3.

Validation of prone intraoperative measurements of global spinal alignment.

OBJECTIVE Verifying the adequacy of surgical correction of adult spinal sagittal deformity (SSD) leads to improved postoperative alignment and clinical outcomes. Traditionally, surgeons relied on intraoperative measurements of lumbar lordosis (LL) correction. However, T-1 pelvic angle (TPA) and its component angles more reliably predict postoperative alignment. While TPA is readily measured on standing radiographs, intraoperative radiographs offer poor resolution of the bicoxofemoral axis. A method to recreate this radiographic landmark by extrapolating preoperative measurements has been described. The authors aimed to assess the reliability of measurements of global spinal alignment obtained via geometrical reconstitution of the bicoxofemoral axis on prone intraoperative radiographs. METHODS A retrospective review was performed. Twenty sets of preoperative standing full-length and intraoperative prone 36-inch lateral radiographs were analyzed. Pelvic incidence (PI) and sacral to bicoxofemoral axis distance (SBFD) were recorded on preoperative films. A perpendicular line was drawn on the intraoperative radiograph from the midpoint of the sacral endplate. This was used as one limb of the PI, and the second limb was digitally drawn at an angle that reproduced the preoperatively obtained PI, extending for a distance that matched the preoperative SBFD. This final point marked the obscured bicoxofemoral axis. These landmarks were used to measure the L-1, T-9, T-4, and T-1 pelvic angles (LPA, T9PA, T4PA, and TPA, respectively) and LL. Two spine fellows and 2 attending spine surgeons made independent measurements and repeated the process in 1 month. Mixed-model 2-way intraclass correlation coefficient (ICC) and Cronbach's α values were calculated to assess interobserver, intraobserver, and scale reliability. RESULTS Interobserver reliability was excellent for preoperative PI and intraoperative LPA, T9PA, and T4PA (ICC = 0.88, 0.84, 0.84, and 0.93, respectively), good for intraoperative TPA (ICC = 0.68), and fair for preoperative SBFD (ICC = 0.60) and intraoperative LL (ICC = 0.50). Cronbach's α was ≥ 0.80 for all measurements. Measuring PI on preoperative standing images had excellent intraobserver reliability for all raters (ICC = 0.89, range 0.80-0.93). All raters but one showed excellent reliability for measuring the SBFD. Reliability for measuring prone LL was good for all raters (ICC = 0.71, range 0.64-0.76). The LPA demonstrated good to excellent reliability for each rater (ICC = 0.76, range 0.65-0.81). The thoracic pelvic angles tended to be more reliable at more distal vertebrae (T9PA ICC = 0.71, range 0.49-0.81; T4PA ICC = 0.62, range 0.43-0.83; TPA ICC = 0.56, range 0.31-0.86). CONCLUSIONS Intraoperative assessment of global spinal alignment with TPA and component angles is more reliable than intraoperative measurements of LL. Reconstruction of preoperatively measured PI and SBFD on intraoperative radiographs effectively overcomes poor visualization of the bicoxofemoral axis. This method is easily adopted and produces accurate and reliable prone intraoperative measures of global spinal alignment.

Traumatic Fractures of the Cervical Spine: Analysis of Changes in Incidence, Cause, Concurrent Injuries, and Complications Among 488,262 Patients from 2005 to 2013.

OBJECTIVE: The causes and epidemiology of traumatic cervical spine fracture have not been described with sufficient power or recency. Our goal is to describe demographics, incidence, cause, spinal cord injuries (SCIs), concurrent injuries, treatments, and complications of traumatic cervical spine fractures. METHODS: A retrospective review was carried out of the Nationwide Inpatient Sample. International Classification of Disease, Ninth Revision E-codes identified trauma cases from 2005 to 2013. Patients with cervical fracture were isolated. Demographics, incidence, cause, fracture levels, concurrent injuries, surgical procedures, and complications were analyzed. t tests elucidated significance for continuous variables and χ2 for categorical variables. Level of significance was P < 0.05. RESULTS: A total of 488,262 patients were isolated (age, 55.96 years; male, 60.0%; white, 77.5%). Incidence (2005, 4.1% vs. 2013, 5.4%), Charlson Comorbidity Index (2005, 0.6150 vs. 2013, 1.1178), and total charges (2005, $71,228.60 vs. 2013, $108,119.29) have increased since 2005, whereas length of stay decreased (2005, 9.22 vs. 2013, 7.86) (all P < 0.05). The most common causes were motor vehicle accident (29.3%), falls (23.7%), and pedestrian accidents (15.7%). The most frequent fracture types were closed at C2 (32.0%) and C7 (20.9%). Concurrent injury rates have significantly increased since 2005 (2005, 62.3% vs. 2013, 67.6%). Common concurrent injuries included fractures to the rib/sternum/larynx/trachea (19.6%). Overall fusion rates have increased since 2005 (2005, 15.7% vs. 2013, 18.0%), whereas decompressions and halo insertion rates have decreased (all P < 0.05). SCIs have significantly decreased since 2005, except for upper cervical central cord syndrome. Complication rates have significantly increased since 2005 (2005, 31.6% vs. 2013, 36.2%). Common complications included anemia (7.7%), mortality (6.6%), and acute respiratory distress syndrome (6.6%). CONCLUSIONS: Incidence, complications, concurrent injuries, and fusions have increased since 2005. Length of stay, SCIs, decompressions, and halo insertions have decreased. Indicated trends should guide future research in management guidelines.

Improving visual estimates of cervical spine range of motion.

Cervical spine range of motion (ROM) is a common measure of cervical conditions, surgical outcomes, and functional impairment. Although ROM is routinely assessed by visual estimation in clinical practice, visual estimates have been shown to be unreliable and inaccurate. Reliable goniometers can be used for assessments, but the associated costs and logistics generally limit their clinical acceptance. To investigate whether training can improve visual estimates of cervical spine ROM, we asked attending surgeons, residents, and medical students at our institution to visually estimate the cervical spine ROM of healthy subjects before and after a training session. This training session included review of normal cervical spine ROM in 3 planes and demonstration of partial and full motion in 3 planes by multiple subjects. Estimates before, immediately after, and 1 month after this training session were compared to assess reliability and accuracy. Immediately after training, errors decreased by 11.9° (flexion-extension), 3.8° (lateral bending), and 2.9° (axial rotation). These improvements were statistically significant. One month after training, visual estimates remained improved, by 9.5°, 1.6°, and 3.1°, respectively, but were statistically significant only in flexion-extension. Although the accuracy of visual estimates can be improved, clinicians should be aware of the limitations of visual estimates of cervical spine ROM. Our study results support scrutiny of visual assessment of ROM as a criterion for diagnosing permanent impairment or disability.

Case reviews of infections of the spine in patients with a history of solid organ transplantation.

STUDY DESIGN: Retrospective clinical case series. OBJECTIVE: To report on the epidemiological, microbiological, and clinical characteristics of spinal infections in patients who have undergone solid organ transplantation. SUMMARY OF BACKGROUND DATA: Spine infections remain a therapeutic challenge, particularly in patients who are immunocompromised. Solid organ transplant patients represent a growing population of immunocompromised hosts. To our knowledge, no previous reports have examined the clinical characteristics spinal infections in this at-risk population in a systematic fashion. METHODS: The records of patients with a history of solid organ transplantation from January 2007 through December 2012 were identified using Current Procedural Terminology procedure codes. Patients with spine infections who have received transplants were then identified using International Classification of Diseases, Ninth Revision codes for spine infection. In addition to demographic data, we recorded medical comorbidities, immunosuppressant medications, laboratory results, culture data, treatment received, and short-term results. RESULTS: During this 6-year period, 2764 solid organ transplants were performed at our institution. Of this cohort, 6 patients (0.22%) were treated for a spinal infection. Patient's age ranged from 51 to 80 years (mean, 63 yr). All spine infections occurred within 1 year after organ transplantation. All patients had an elevated erythrocyte sedimentation rate. Only 1 patient had an elevated white blood cell count. The most common organisms were Escherichia coli and Staphylococcus. Four patients required surgical treatment. All patients had complete resolution of symptoms. CONCLUSION: Our data suggest that patients with a history of solid organ transplantation may be more susceptible to developing spine infections than the general population. The most common organisms in our cohort were E. coli and Staphylococcus. Spine infections caused by atypical organisms do also occur in the organ transplant population, as is the case in other immunocompromised patients. The identification of these organisms and timely institution of treatment remains critical in the management of this at-risk population. LEVEL OF EVIDENCE: 4.

Surgical management of lumbar degenerative spondylolisthesis.

Lumbar degenerative spondylolisthesis (DS) is a common cause of low back pain, radiculopathy, and/or neurogenic claudication. Treatment begins with a trial of nonsurgical methods, including physical therapy, NSAIDs, and epidural corticosteroid injections. Surgical treatment with decompression and fusion is recommended for patients who do not respond to this initial regimen. Although much has been published in the past two decades on the surgical management of DS, the optimal method remains controversial. Interbody fusion may improve arthrodesis rates and can be performed via numerous surgical approaches. Minimally invasive techniques continue to be developed. Particular attention to surgical management of DS in the elderly is warranted given the increasing numbers of elderly persons. Healthcare utilization in the future must take into account evidence-based medicine that establishes clinically effective practices while simultaneously being cost effective.

A radiographic study of the ossification of the posterior wall of the acetabulum: implications for the diagnosis of pediatric and adolescent hip disorders.

BACKGROUND: Subtle variations in acetabular morphology have been implicated in several pathologic hip conditions. Although it is understood that the acetabulum forms at the junction of the ilium, ischium, and pubis at the triradiate cartilage, the ossification and development pattern of the posterior wall of the acetabulum is unknown. Standard radiographs and computed tomographic scans used in evaluation of the adolescent hip do not allow a complete assessment of the non-ossified portions of the developing acetabulum. The purpose of this study was to define the currently unknown ossification pattern and development of the posterior wall of the acetabulum and to determine when conventional imaging, with use of computed tomography and radiographs, is appropriate. METHODS: One hundred and eighty magnetic resonance imaging examinations in patients who were four to fifteen years old were evaluated by a musculoskeletal radiologist for ossification patterns of the posterior wall of the acetabulum and triradiate cartilage. Correlations were made with available radiographs. RESULTS: Posterior acetabular wall ossification lags behind anterior wall ossification throughout development. On average, the posterior wall of the acetabulum began to ossify at the chronological age of eight years, followed by a discrete rim of posterior calcification (posterior rim sign) at the patient age of twelve years, just prior to the fusion of the posterior acetabular wall elements to the pelvis. This preceded the closure of the triradiate cartilage in all subjects. On average, male patients had fusion of the posterior wall of the acetabulum one to 1.5 years after female patients. CONCLUSIONS: The ossification of the posterior wall of the acetabulum is completed in a predictable manner prior to closure of the triradiate cartilage.

The effect of therapies for osteoporosis on spine fusion: a systematic review.

BACKGROUND CONTEXT: Fusion of the spine requires de novo bone formation and remodeling, processes that rely heavily on the action of the osteoblast and osteoclast. Bisphosphonate drugs and intermittent parathyroid hormone (PTH) therapy are widely prescribed to treat osteoporosis and act on the osteoblast/osteoclast complex. The impact of these medications on spine fusion is not known. PURPOSE: To evaluate the available evidence on the potential impact of bisphosphonates and PTH on fusion rate and fusion quality in spinal arthrodesis. STUDY DESIGN: A systematic review of the literature. PATIENT SAMPLE: All available literature regarding the impact of bisphosphonates and PTH on spinal fusion. OUTCOME MEASURES: Fusion rate and histologic, microstructural, or biomechanical measures of fusion quality. METHODS: A systematic review of the literature published between 1980 and 2011 was conducted using major electronic databases. The results of studies meeting criteria for inclusion were then aggregated and examined for consensus on the effect of these medications on spine fusion. RESULTS: The literature contained 18 animal studies and one clinical trial investigating the impact of these medications on spine fusion. Most animal studies evaluating the impact of bisphosphonates on fusion rate have not found statistically significant changes with treatment, although this fact may be attributable to low statistical power. The animal literature does suggest that bisphosphonate therapy results in a less histologically mature fusion mass; however, the impact of these changes on fusion mass biomechanics is unclear. The only available human study suggests that these bisphosphonates may increase the radiographically defined fusion rate but did not demonstrate an impact on clinical outcome. In animals, PTH improves the fusion rate and fusion mass microstructure, but data on its effect on fusion mass biomechanics are lacking. No studies have evaluated the impact of PTH on spine fusion in humans. CONCLUSIONS: In animals, bisphosphonate therapy appears to impede maturation of the fusion mass, with an unclear effect on mechanical strength. This effect was not seen in the lone human study, which suggested that these medications improved the radiographically defined fusion rate. The available animal studies on intermittent PTH treatment suggest that it may improve fusion rate and fusion mass microstructure. Given the widespread use of these agents, further investigation into their impact on human spine fusion is necessary to inform the care of patients with osteoporosis who are undergoing spine surgery.

Mild intraoperative hypothermia reduces free tissue transfer thrombosis.

Patients undergoing free tissue transfer are particularly susceptible to hypothermia. The goal was to investigate the impact of intraoperative core body temperature on free flap thrombosis. Two hundred twelve cases of free flap reconstruction at Yale-New Haven Hospital between 1992 and 2008 were reviewed. Free flap thrombosis was defined by complete flap necrosis or direct visualization of arterial or venous thrombosis. Temperature measurements were calibrated to bladder temperatures as measured by Foley catheter sensor. Through logistic regression analysis, maximum and minimum intraoperative temperatures were determined to be statistically significant predictors of free flap thrombosis. The optimal temperature was calculated to be 36.2 °C, and maximum intraoperative temperatures between 36.0 °C and 36.4 °C showed lower thrombosis rates than super-warmed patients ( P < 0.03). Therefore, free flap patients should be mildly hypothermic at 36.0 °C to 36.4 °C, compared with normothermia at 37.5 °C, as measured in the bladder. A prospective randomized trial investigating thrombosis rates and intraoperative temperature should be undertaken.