Do Hounsfield Units From Intraoperative CT Scans Correlate With Preoperative Values?

BACKGROUND: There is increasing interest in forecasting postoperative complications using bone density metrics. Vertebral Hounsfield unit measurements obtained from CT scans performed for surgical planning or other purposes, known as opportunistic CTs, have shown promise for their ease of measurement and the ability to target density measurement to a particular region of interest. Concomitant with the rising interest in prognostic bone density measurement use has been the increasing adoption of intraoperative advanced imaging techniques. Despite the interest in both outcome prognostication and intraoperative advanced imaging, there is little information regarding the use of CT-based intraoperative imaging as a means to measure bone density. QUESTIONS/PURPOSES: (1) Can vertebral Hounsfield units be reliably measured by physician reviewers from CT scans obtained intraoperatively? (2) Do Hounsfield units measured from intraoperative studies correlate with values measured from preoperative CT scans? METHODS: To be eligible for this retrospective study, patients had to have been treated with the use of an intraoperative CT scan for instrumented spinal fusion for either degenerative conditions or traumatic injuries between January 2015 and December 2022. Importantly, patients without a preoperative CT scan of the fused levels within 180 days before surgery or who were indicated for surgery because of infection, metastatic disease, or who were having revision surgery after prior instrumentation were excluded from the query. Of the 285 patients meeting these inclusion criteria, 53% (151) were initially excluded for the following reasons: 36% (102) had intraoperative CT scans obtained after placement of instrumentation, 16% (47) had undergone intraoperative CT scans but the studies were not accessible for Hounsfield unit measurement, and 0.7% (2) had prior kyphoplasty wherein the cement prevented Hounsfield unit measurement. Finally, an additional 19% (53) of patients were excluded because the preoperative CT and intraoperative CT were obtained at different peak voltages, which can influence Hounsfield unit measurement. This yielded a final population of 81 patients from whom 276 preoperative and 276 intraoperative vertebral Hounsfield unit measurements were taken. Hounsfield unit data were abstracted from the same vertebra(e) from both preoperative and intraoperative studies by two physician reviewers (one PGY3 and one PGY5 orthopaedic surgery resident, both pursuing spine surgery fellowships). For a small, representative subset of patients, measurements were taken by both reviewers. The feasibility and reliability of Hounsfield unit measurement were then assessed with interrater reliability of values measured from the same vertebra by the two different reviewers. To compare Hounsfield unit values from intraoperative CT scans with preoperative CT studies, an intraclass correlation using a two-way random effects, absolute agreement testing technique was employed. Because the data were formatted as multiple measurements from the same vertebra at different times, a repeated measures correlation was used to assess the relationship between preoperative and intraoperative Hounsfield unit values. Finally, a linear mixed model with patients handled as a random effect was used to control for different patient and clinical factors (age, BMI, use of bone density modifying agents, American Society of Anesthesiologists [ASA] classification, smoking status, and total Charlson comorbidity index [CCI] score). RESULTS: We found that Hounsfield units can be reliably measured from intraoperative CT scans by human raters with good concordance. Hounsfield unit measurements of 31 vertebrae from a representative sample of 10 patients, measured by both reviewers, demonstrated a correlation value of 0.82 (95% CI 0.66 to 0.91), indicating good correlation. With regard to the relationship between preoperative and intraoperative measurements of the same vertebra, repeated measures correlation testing demonstrated no correlation between preoperative and intraoperative measurements (r = 0.01 [95% CI -0.13 to 0.15]; p = 0.84). When controlling for patient and clinical factors, we continued to observe no relationship between preoperative and intraoperative Hounsfield unit measurements. CONCLUSION: As intraoperative CT and measurement of vertebral Hounsfield units both become increasingly popular, it would be a natural extension for spine surgeons to try to extract Hounsfield unit data from intraoperative CTs. However, we found that although it is feasible to measure Hounsfield data from intraoperative CT scans, the obtained values do not have any predictable relationship with values obtained from preoperative studies, and thus, these values should not be used interchangeably. With this knowledge, future studies should explore the prognostic value of intraoperative Hounsfield unit measurements as a distinct entity from preoperative measurements. LEVEL OF EVIDENCE: Level III, diagnostic study.

Preoperative Predictors of Arthroscopic Partial Meniscectomy Outcomes: The APM Index Score.

BACKGROUND: Preoperative risk factors contributing to poor outcomes after arthroscopic partial meniscectomy (APM) have not yet been consolidated and codified into an index scoring system used to predict APM success. PURPOSE: To create an index score using available preoperative factors to predict the likelihood of favorable postoperative outcomes after APM. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A consecutive cohort of patients undergoing primary APM were enrolled in this study. Patients completed pre- and postoperative patient-reported outcome measure (PROM) questionnaires that included the Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS) for pain, Veterans RAND 12-Item Health Survey (VR-12 Physical and Mental), and Marx Activity Rating Scale (MARS). Multivariable logistic regression models were performed to evaluate independent predictors of KOOS Pain, Symptoms, and Activities of Daily Living scores and achievement of the minimal clinically important difference (MCID) and substantial clinical benefit (SCB). The authors assigned points to each variable proportional to its odds ratio, rounded to the nearest integer, to generate the index score. RESULTS: In total, 468 patients (mean age, 49 years [SD, 10.4 years; range, 19-81 years]) were included in this study. In the univariate analysis, shorter symptom duration, lower Kellgren-Lawrence (KL) grade, lower preoperative KOOS Pain value, and lower VR-12 Physical score were associated with a higher likelihood of clinical improvement at 1 year. In the multivariable model for clinical improvement with MCID, symptom duration (<3 months: OR, 3.00 [95% CI, 1.45-6.19]; 3-6 months: OR, 2.03 [95% CI, 1.10-3.72], compared with >6 months), KL grade (grade 0: OR, 3.54 [95% CI, 1.66-7.54]; grade 1: OR, 3.04 [95% CI, 1.48-6.26]; grade 2: OR, 2.31 [95% CI, 1.02-5.27], compared with grade 3), and preoperative KOOS Pain value (score <45: OR, 3.00 [95% CI, 1.57-5.76]; score of 45-60: OR, 2.80 [95% CI, 1.47-5.35], compared with score >60) were independent significant predictors for clinical improvement. The scoring algorithm demonstrated that a higher total score predicted a higher likelihood of achieving the MCID: 0 = 40%, 1 = 68%, 2 = 80%, 3 = 89%, and 4 = 96%. CONCLUSION: Using this model, the authors developed an index score that, using preoperative factors, can help identify which patients will achieve clinical improvement after APM. Longer symptom duration and higher KL grade were associated with a decreased likelihood of clinical improvement as measured by KOOS Pain at 1 year postoperatively.

Increased cage angle effects on radiographic outcomes after stand-alone anterior lumbar interbody fusion.

OBJECTIVE: Anterior lumbar interbody fusion (ALIF) is a well-accepted surgical technique used to treat various lumbar degenerative pathologies. Recently, hyperlordotic cages have been introduced to create higher degrees of lordosis to the lumbar spine. There are little data currently available to define the radiographic benefits that these cages provide with stand-alone ALIF. The goal of the present study was to assess the effect of increasing cage angles on postoperative subsidence, sagittal alignment, and foraminal and disc height in patients who underwent single-level stand-alone ALIF surgery. METHODS: A retrospective cohort study was performed of consecutive patients who underwent single-level ALIF by a single spine surgeon. Radiographic analysis included global lordosis, operative level of segmental lordosis, cage subsidence, sacral slope, pelvic tilt, pelvic incidence, pelvic incidence-lumbar lordosis mismatch, edge loading, foraminal height, posterior disc height, anterior disc height, and adjacent-level lordosis. Multivariate linear and logistic regressions were performed to analyze the relationship between cage angle and radiographic outcomes. RESULTS: Seventy-two patients were included in the study and divided into three groups based on cage angle: < 10° (n = 17), 10°-15° (n = 36), and > 15° (n = 19). Within the entire study cohort, there were significant improvements in disc and foraminal height, as well as segmental and global lordosis, at the final follow-up after single-level ALIF. However, when stratified by cage angle groups, patients with > 15° cages did not have any additional significant changes in global or segmental lordosis compared with those patients with smaller cage angles, but patients with > 15° cages showed greater risk of subsidence while also having significantly less improvements in foraminal height, posterior disc height, and average disc height compared with the other groups. CONCLUSIONS: Patients with < 15° stand-alone ALIF cages showed improved average foraminal and disc (posterior, anterior, and average) height without sacrificing improvements in sagittal parameters or increasing risk of subsidence when compared to patients with hyperlordotic cages. The use of hyperlordotic cages > 15° did not provide spinal lordosis commensurate with the lordotic angle of the cage and had a greater risk of subsidence. Although this study was limited by a lack of patient-reported outcomes to correlate with radiographic results, these findings support the judicious use of hyperlordotic cages in stand-alone ALIF.

Physician Decision-making in Return to Play After Cervical Spine Injury: A Descriptive Analysis of Survey Data.

OF BACKGROUND DATA: Cervical spine injuries commonly occur during athletic play, and such injuries carry significant risk for adverse sequelae if not properly managed. Although guidelines for managing return to play exist, adherence among spine surgeons has not been thoroughly examined. STUDY DESIGN: Prospective analysis of survey data collected from surgeon members of the Cervical Spine Research Society (CSRS) and the International Society for the Advancement of Spine Surgery (ISASS). OBJECTIVE: The objective of this study was to characterize consensus among spine surgeons regarding decision-making on return to competitive sports and level of impact following significant cervical spine injuries from real-life scenarios. MATERIALS AND METHODS: Return to play decisions for 15 clinical cervical spine injury scenarios were compared with current guidelines. Surgeon demographic information such as orthopedic board certification status and years in practice were also analyzed. Weighted kappa analysis was utilized to determine interrater reliability in survey responses. RESULTS: Survey respondents had a poor agreement with both Watkins and Torg guidelines (average weighted κ of 0.027 and 0.066, respectively). Additional kappa analysis of surgeon agreement regarding the "Types of Play" and "Level of Play" for return was still remained poor (Kendall W of 0.312 and 0.200, respectively). Responses were also significantly influenced by surgeon demographics. CONCLUSIONS: There is poor consensus among spine surgeons for return to play following cervical spine injury. These results support the concept that given the gravity of cervical spine injuries, a more standardized approach to decision-making regarding return to play after cervical spine injury is necessary.

Paternal contribution to embryonic competence.

INTRODUCTION: The effect of paternal characteristics on embryo development and the outcome of preimplantation genetic testing for aneuploidy have not been extensively explored. This study investigates the association of sperm parameters, insemination, and extraction techniques, with the rate of embryo aneuploidy. This study sought to evaluate the association between male factor infertility and embryo aneuploidy. MATERIAL AND METHODS: Patients underwent in vitro fertilization using intracytoplasmic sperm injection, with preimplantation genetic testing for aneuploidy. Patients were divided into four groups by sperm parameters: Group A: oligozoospermia (sperm concentration <10 million, morphology > 4%); Group B: teratozoospermia (sperm concentration >10 million, morphology <4%); Group C: oligozoospermia and teratozoospermia (sperm concentration <10 million, morphology <4%); Group D: controls. Additionally, couples were divided into three categories by days of abstinence: Group A: <2; Group B: 2-7; and Group C: >7. RESULTS: A total of 4108 in vitro fertilization cycles with preimplantation genetic testing for aneuploidy were analyzed. After controlling for parental age and follicle count, the rate of embryo aneuploidy was not affected by duration of abstinence, sperm parameters, or the source of the sperm sample. CONCLUSIONS: Numerous factors related to sperm source and quality were evaluated, and a minimal influence on the rate of embryo aneuploidy was observed.

Thirty-Day Perioperative Complications, Prolonged Length of Stay, and Readmission Following Elective Posterior Lumbar Fusion Associated With Poor Nutritional Status.

STUDY DESIGN: Retrospective study. OBJECTIVE: To determine the rates of early postoperative mortality and morbidity in adults with hypoalbuminemia undergoing elective posterior lumbar fusion (PLF). METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) was examined from 2005 to 2012. Current Procedural Terminology (CPT) codes were used to query the database for adults (≥18 years) who underwent PLF and/or posterior/transforaminal lumbar interbody fusion (PLIF/TLIF). Patients were divided into those with normal albumin concentration (≥3.5g/dL) and those with hypoalbuminemia (<3.5 g/dL). Both univariate and multivariate analyses were performed. RESULTS: A total of 2410 patients were included, of whom 2251 (93.4%) were normoalbuminemic and 159 (6.6%) were hypoalbuminemic. Patients with preoperative serum albumin levels <3.5 g/dL were older with a higher American Society of Anesthesiologists (ASA) score, and more comorbidities, including anemia, diabetes, dependent functional status, and preoperative history of chronic steroid therapy. Hypoalbuminemic patients had higher rates of any 30-day perioperative complication (P < .001), unplanned readmission (P = .019), and prolonged length of stay (LOS) >5 days (P < .001). However, hypoalbuminemia was not significantly associated with any specific perioperative complication. On multivariate analysis, preoperative hypoalbuminemia was found to be an independent predictor of prolonged LOS (OR 2.4, 95% CI 1.7-3.5; P < .001) and unplanned readmission (OR 2.7, 95% CI 1.1-6.3; P = .023). CONCLUSION: Hypoalbuminemia was found to be an important predictor of patient outcomes in this population. This study suggests that clinicians should consider nutritional screening and optimization as part of the preoperative risk assessment algorithm. LEVEL OF EVIDENCE: III.

Elevated glycohemoglobin HbA1c is associated with low back pain in nonoverweight diabetics.

BACKGROUND CONTEXT: Low back pain (LBP) is a common complaint in clinical practice of multifactorial origin. Although obesity has been thought to contribute to LBP primarily by altering the distribution of mechanical loads on the spine, the additional contribution of obesity-related conditions such as diabetes mellitus (DM) to LBP has not been thoroughly examined. PURPOSE: To determine if there is a relationship between DM and LBP that is independent of body mass index (BMI) in a large cohort of adult survey participants. STUDY DESIGN: Retrospective analysis of prospectively collected National Health and Nutrition Examination Survey (NHANES) data to characterize associations between LBP, DM, and BMI in adults subdivided into 6 subpopulations: normal weight (BMI 18.5-25), overweight (BMI 25-30), and obese (BMI >30) diabetics and nondiabetics. Diabetes was defined with glycohemoglobin A1c (HbA1c) ≥6.5%. PATIENT SAMPLE: 11,756 participants from NHANES cohort. OUTCOME MEASURES: Percentage of LBP reported. METHODS: LBP reported in the 1999-2004 miscellaneous pain NHANES questionnaire was the dependent variable examined. Covariates included HbA1c, BMI, age, and family income ratio to poverty as continuous variables as well as race, gender, and smoking as binary variables. Individuals were further subdivided by weight class and diabetes status. Regression and graphical analyses were performed on the study population as a whole and also on subpopulations. RESULTS: Increasing HbA1c did not increase the odds of reporting LBP in the full cohort. However, multivariate logistic regression of the 6 subpopulations revealed that the odds of LBP significantly increased with increasing HbA1c levels in normal weight diabetics. No other subpopulations reported significant relationships between LBP and HbA1c. LBP was also significantly associated with BMI for normal weight diabetics and also for obese subjects regardless of their DM status. CONCLUSIONS: LBP is significantly related to DM status, but this relationship is complex and may interact with BMI. These results support the concept that LBP may be improved in normal weight diabetic subjects with improved glycemic control and weight loss, and that all obese LBP subjects may benefit from improved weight loss alone.

Risk Factors for Perioperative Complications in Morbidly Obese Patients Undergoing Elective Posterior Lumbar Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: The prevalence of obesity-related low back pain and degenerative disc disease is on the rise. Past studies have demonstrated that obesity is associated with higher perioperative complication rates, but there remains a gap in the literature regarding additional risk factors that further predispose this already high-risk patient population to poor surgical outcomes following elective posterior lumbar fusion (PLF). The aim of the study is to identify independent risk factors for poor 30-day perioperative outcomes in morbidly obese patients undergoing elective PLF. METHODS: We identified 22 909 patients in the American College of Surgeons National Surgical Quality Improvement Program database who underwent elective PLF. There were 1861 morbidly obese patients. Baseline patient demographics and medical comorbidities were collected. Univariate analysis was performed to compare perioperative complication rates between non-morbidly obese and morbidly obese patients. The 5 most common complications in the morbidly obese group were then selected for multivariate regression analysis to identify independent risk factors for poor 30-day outcomes. RESULTS: Morbidly obese patients had a higher perioperative complication rate. The 5 most common complications were prolonged hospitalization, blood transfusion, readmission, wound complications, and reoperation. Independent risk factors for these complications were age ≥65 years, super obesity (ie, BMI > 48.6), chronic steroid use, American Society of Anesthesiology classification ≥3, poor functional status, long length of fusion ≥4 levels, and extended operative time (ie, operative time ≥318 minutes). CONCLUSIONS: Morbidly obese patients are at higher risk of perioperative complications following elective PLF. Modifiable risk factors for the most common complications are obesity and preoperative steroid use.

Preoperative Nutritional Status as a Risk Factor for Major Postoperative Complications Following Anterior Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective study. OBJECTIVES: To determine rates of medical and surgical postoperative complications in adults with hypoalbuminemia undergoing anterior lumbar interbody fusion (ALIF). METHODS: This was a retrospective analysis of prospectively collected data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database of patients (≥18 years old) undergoing ALIF procedures, identified by CPT (Current Procedural Terminology) code from 2011 to 2014. Poor nutritional status was defined by a preoperative serum albumin level <3.5 g/dL, and albumin levels above this were considered normal. Multivariate logistic regression models were utilized to assess preoperative risk factors including nutritional status as predictors of specific postoperative complications. Significance was defined as P < .05 and odds ratios (ORs) were calculated with a 95% confidence interval (CI). This model was used to determine the strength of nutritional status as an adjusted predictor of adverse postoperative events. RESULTS: There were 3184 ALIF cases, including 1,275 (40%) of which had preoperative serum albumin levels. 53 (4.15%) patients were classified as having poor nutrition status. Poor preoperative nutritional status was shown to be a strong independent predictor of length of stay ≥5 days (OR = 2.56, 95% CI 1.43-4.59, P = .002), urinary tract infection (OR = 5.93, 95% CI 2.11-16.68, P = .001), and sepsis (OR = 5.35, 95% CI 1.13-25.42, P = .035) compared to patients with normal preoperative serum albumin levels. CONCLUSIONS: Our analysis shows that patients with poor nutritional status before ALIF are independently at risk for sepsis as well as increased length of stay and urinary tract infection.

Predicting Surgical Complications in Patients Undergoing Elective Adult Spinal Deformity Procedures Using Machine Learning.

STUDY DESIGN: Cross-sectional database study. OBJECTIVE: To train and validate machine learning models to identify risk factors for complications following surgery for adult spinal deformity (ASD). SUMMARY OF BACKGROUND DATA: Machine learning models such as logistic regression (LR) and artificial neural networks (ANNs) are valuable tools for analyzing and interpreting large and complex data sets. ANNs have yet to be used for risk factor analysis in orthopedic surgery. METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried for patients who underwent surgery for ASD. This query returned 4,073 patients, which data were used to train and evaluate our models. The predictive variables used included sex, age, ethnicity, diabetes, smoking, steroid use, coagulopathy, functional status, American Society of Anesthesiologists (ASA) class >3, body mass index (BMI), pulmonary comorbidities, and cardiac comorbidities. The models were used to predict cardiac complications, wound complications, venous thromboembolism (VTE), and mortality. Using ASA class as a benchmark for prediction, area under receiver operating characteristic curves (AUC) was used to determine the accuracy of our machine learning models. RESULTS: The mean age of patients was 59.5 years. Forty-one percent of patients were male whereas 59.0% of patients were female. ANN and LR outperformed ASA scoring in predicting every complication (p<.05). The ANN outperformed LR in predicting cardiac complication, wound complication, and mortality (p<.05). CONCLUSIONS: Machine learning algorithms outperform ASA scoring for predicting individual risk prognosis. These algorithms also outperform LR in predicting individual risk for all complications except VTE. With the growing size of medical data, the training of machine learning on these large data sets promises to improve risk prognostication, with the ability of continuously learning making them excellent tools in complex clinical scenarios. LEVEL OF EVIDENCE: Level III.

The Seven-Year Cost-Effectiveness of Anterior Cervical Discectomy and Fusion Versus Cervical Disc Arthroplasty: A Markov Analysis.

STUDY DESIGN: Markov model analysis. OBJECTIVE: The aim of this study was to determine the 7-year cost-effectiveness of single-level anterior cervical discectomy and fusion (ACDF) versus cervical disc replacement (CDR) for the treatment of cervical disc degeneration. SUMMARY OF BACKGROUND DATA: Both ACDF and CDR are acceptable surgical options for the treatment of symptomatic cervical disc degeneration. Past studies have demonstrated at least equal effectiveness of CDR when compared with ACDF in large randomized Investigational Device Exemption (IDE) studies. Short-term cost-effectiveness analyses at 5 years have suggested that CDR may be the preferred treatment option. However, adjacent segment disease and other postoperative complications may occur after 5 years following surgery. METHODS: A Markov model analysis was used to evaluate data from the LDR Mobi-C IDE study, incorporating five Markov transition states and seven cycles with each cycle set to a length of 1 year. Transition state probabilities were determined from complication rates, as well as index and adjacent segment reoperation rates from the IDE study. Raw SF-12 data were converted to health state utility values using the SF-6D algorithm for 174 CDR patients and 79 ACDF patients. RESULTS: Assuming an ideal operative candidate who is 40-years-old and failed appropriate conservative care, the 7-year cost was $103,924 for ACDF and $105,637 for CDR. CDR resulted in the generation of 5.33 quality-adjusted life-years (QALYs), while ACDF generated 5.16 QALYs. Both ACDF and CDR were cost-effective, but the incremental cost-effectiveness ratio (ICER) was $10,076/QALY in favor of CDR, which was less than the willingness-to-pay (WTP) threshold of $50,000/QALY. CONCLUSION: ACDF and CDR are both cost-effective strategies for the treatment of cervical disc degeneration. However, CDR is the more cost-effective procedure at 7 years following surgery. Further long-term studies are needed to validate the findings of this model. LEVEL OF EVIDENCE: 1.