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.

Opioid-Sparing Nonsteroid Anti-inflammatory Drugs Protocol in Patients Undergoing Intramedullary Nailing of Tibial Shaft Fractures: A Randomized Control Trial.

INTRODUCTION: Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective analgesics commonly used in fracture management. Although previously associated with delayed fracture healing, multiple studies have demonstrated their safety, with minimal risks of fracture healing. Given the current opioid crisis in the United States, alternate pain control modalities are essential to reduce opioid consumption. This study aims to determine whether the combination of oral acetaminophen and intravenous ketorolac is a viable alternative to opioid-based pain management in closed tibial shaft fractures treated with intramedullary nailing. METHODS: We conducted a randomized controlled trial evaluating postoperative pain control and opioid consumption in patients with closed tibial shaft fractures who underwent intramedullary nailing. Patients were randomized into an NSAID-based pain control group (52 patients) and an opioid-based pain control group (44 patients). Visual analog scale (VAS) scores and morphine milligram equivalents (MMEs) were evaluated at 12-hour postoperative intervals during the first 48 hours after surgery. Nonunion and delayed healing rates were recorded for both groups. RESULTS: A statistically significant decrease in MMEs was noted at every measured interval (12, 24, 36, and 48 hours) in the NSAID group compared with the opioid group ( P -value 0.001, 0.001, 0.040, 0.024, respectively). No significant change in visual analog scale scores was observed at 12, 36, and 48 hours between both groups ( P -value 0.215, 0.12, and 0.083, respectively). A significant decrease in VAS scores was observed at the 24-hour interval in the NSAID group compared with the opioid group ( P -value 0.041). No significant differences in union rates were observed between groups ( P -value 0.820). DISCUSSION: Using an NSAID-based postoperative pain protocol led to a decrease in opioid consumption without affecting pain scores or union rates. Owing to the minimal risk of short-term NSAID use, their role in the perioperative management of tibia shaft fractures is justified, especially when they reduce opioid consumption markedly. LEVEL OF EVIDENCE: Therapeutic Level I.

Predictors of Outcomes After Lumbar Intra-Articular Facet Joint Injections and Medial Branch Blocks: A Scoping Review.

STUDY DESIGN: A scoping review. OBJECTIVE: We aimed to identify and describe the factors associated with the patient-reported response after lumbar intra-articular facet joint (FJ) injections or medial branch blocks (MBBs). SUMMARY OF BACKGROUND DATA: FJ osteoarthritis is among the most common causes of chronic low back pain. Management often includes FJ intra-articular injection and MBBs (which may be followed by radiofrequency ablation of the nerves innervating these joints). However, the success of these approaches is variable, prompting interest in identifying patient characteristics (imaging features, clinical signs, and among others) associated with response to these types of facet injections. MATERIALS AND METHODS: We performed a literature search on factors associated with patient-reported outcomes after lumbar FJ intra-articular injections or MBBs for patients with low back pain published in English or Spanish between 2000 and 2023. We excluded duplicate papers that did not describe factors associated with outcomes or those describing other interventions. We collected data on the association of these factors with patient-reported outcomes. RESULTS: Thirty-seven studies met the inclusion criteria and were analyzed. These studies evaluated factors, such as age, depression, and single photon emission computed tomography (SPECT), and among variables. Age and imaging findings of facet arthropathy were the most frequently described factors. Imaging findings of FJ arthropathy and positive SPECT were often associated with positive results after intra-articular FJ injections or MBBs. In contrast, younger age and smoking were frequently associated with less favorable clinical outcomes. CONCLUSION: Numerous factors were considered in the 37 studies included in this review. Imaging findings of facet arthropathy, duration of pain, and positive SPECT were consistently associated with favorable results after facet interventions.

Associated factors of patients with spinal stenosis who undergo reoperation after a posterior lumbar spinal fusion in a Hispanic-American population.

PURPOSE: The aim of this study was to evaluate the associated factors of patients with LSS who undergo reoperation after a PLSF in a Hispanic-American population. METHODS: A retrospective single-center review was performed from all non-age-related Hispanic-Americans with LSS who underwent one or two-level PLSF from 2008 to 2018. Baseline characteristics were analyzed between the reoperation and no-reoperation group using a bivariate and multivariate analyses. RESULTS: Out of 425 patients who underwent PLSF, 38 patients underwent reoperation. At a two-year follow-up, the reoperation rate was 6.1% (26/425), mostly due to pseudoarthrosis (39.5%), recurrent stenosis (26.3%), new condition (15.8%), infection (10.5%), hematoma (5.3%), and dural tear (2.6%). Patients who underwent reoperation were more likely to have a preoperative history of epidural steroid injection (ESI) (OR 5.18, P = 0.009), four or more comorbidities (OR 2.69, P = 0.028), and operated only with a posterolateral fusion without intervertebral fusion (OR 2.15, P = 0.032). Finally, the multivariable analysis showed that ESI was the only independent associated factor in patients who underwent reoperation after a PLSF in our group. CONCLUSION: Among this population who underwent surgery, a reoperation rate at two years of follow-up was less than ten percent. Our study did not find any associated factor inherent to Hispanic-Americans, as ethnic group, who were reoperated after LSS.