Association between cervical fracture patterns and blunt cerebrovascular injury when screened with computed tomographic angiography.

BACKGROUND CONTEXT: Prior studies have demonstrated a close association between cervical spine fractures and blunt cerebrovascular injuries (BCVI). Undiagnosed BCVI is a feared complication because of the potentially catastrophic outcomes in a missed posterior circulation stroke. Computed tomography angiography (CTA) is commonly used to screen BCVI in the trauma setting. However, determining which cervical fracture patterns mandate screening is still not clearly known. PURPOSE: The aim of this retrospective review is to further elucidate which fracture patterns are associated with BCVI when using CTA and may mandate screening. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: All patients that presented to our trauma and emergency departments with a blunt cervical spine fracture from January 2018 to December 2021. Inclusion criteria included blunt cervical trauma and the use of CTA for BCVI screening. Exclusion criteria included patients under the age of 18, penetrating cervical trauma, and use any imaging modality besides CTA for BCVI screening. OUTCOME MEASURES: Patient demographics (age, gender, Glasgow coma scale, hospital length of stay (LOS), intensive care unit LOS, mechanism of energy of injury, polytrauma status), fracture location, fracture pattern (anterior arch, dens, dislocations/subluxations, facet, hangman, Jefferson, lamina, lateral mass, occipital condyle dissociation, occipital condyle, pedicle, posterior arch, spinous process, transverse process, transverse foramen, and vertebral body), and whether the patient sustained a BCVI or CVA. METHODS: If a patient had multiple fracture levels or fracture patterns, each level and pattern was counted as a separate BCVI. Multilevel fractures were defined as any patient with fractures at two distinct cervical levels. Differences between the patients who had a BCVI and those who did not were analyzed using independent sample t-tests for continuous variables and the chi-square or Fisher exact test for categorical variables. Odds ratios and 95% confidence intervals were calculated to assess likelihood between patient characteristics/fracture characteristics and BCVI. RESULTS: A total of 690 patients were identified as having a blunt cervical spine injury. A total of 453 patients (66%) underwent screening for BCVI with CTA. Among patients who underwent CTA, BCVI was diagnosed in 138 patients (30%), VAI in 119 patients (26%), CAI in 30 patients (7%), and 11 patients were diagnosed with both a VAI and CAI (2%). Overall, among all patients there were 9 strokes, all in patients identified with a BCVI (1%). No individual cervical level was associated with increased risk of BCVI, but when combined, OC-C3 fractures were associated with an increased risk (OR: 1.4, 95% CI: 1.0-1.9, p-value: .006). Multilevel fractures were also associated with an increased risk (OR: 1.7, 95% CI: 1.1-2.3, p-value: .01). The only fracture pattern associated with increased risk of BCVI were fractures associated with a dislocation/subluxation (OR: 3.8, 95% CI: 1.9-7.8, p-value = .0001). CONCLUSIONS: The only fracture pattern associated with an increased risk of BCVI were fractures associated with dislocation/subluxation. The only fracture levels associated with BCVI were combined OC-C3 and multilevel fractures. We recommend that any upper cervical fracture (OC-C3), multilevel fracture, or fracture with dislocation/subluxation undergo screening for BCVI.

Cervical fracture patterns associated with blunt cerebrovascular injures when utilizing computed tomographic angiography: a systematic review and meta-analysis.

BACKGROUND CONTEXT: Prior studies have demonstrated an association between cervical spine fractures and blunt cerebrovascular injuries (BCVI) due to the intimate anatomic relationship between the cervical spine and the vertebral arteries. Digital subtraction angiography (DSA) has historically been the gold standard, but computed tomography angiography (CTA) is commonly used to screen for BCVI in the trauma setting. However, there is no consensus regarding which fracture patterns mandate screening. Over aggressive screening may lead to increased radiation, increased false positives, and overtreatment of patients which can cause unnecessary patient harm, and increased healthcare costs. PURPOSE: The aim of this meta-analysis is to analyze which cervical spine fracture patterns are most predictive of BCVI when utilizing CTA. STUDY DESIGN/SETTING: Systematic review and meta-analysis. OUTCOME MEASURES: Odds ratios for specific cervical fracture patterns and risk of developing a BCVI. METHODS: A systematic literature review of all English language studies from 2000-2020 was conducted. The year 2000 was chosen as the cut-off because use of CTA prior to 2000 was rare. Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Scopus, Global Index Medicus, and ClinicalTrials.gov were queried. Studies were included if they met the following criteria: (1) the diagnostic imaging modality was CTA; (2) investigated blunt cervical trauma; (3) noted specific cervical spine fracture patterns associated with BCVI; (4) odds ratios for specific cervical spine fracture patterns or the odds ratio could be calculated; (5) subjects were 18 years old or older. Studies were excluded if they: (1) included DSA or magnetic resonance imaging; (2) included penetrating cervical trauma; (3) included pediatric patients less than 18 years of age; (4) were not written in English. All statistical analysis was performed using R Studio (RStudio, Boston, MA, USA). RESULTS: The initial search, after duplicates were removed, resulted in 10,940 articles for independent review. Six studies met the criteria for inclusion in the meta-analysis. Specific fracture patterns mentioned are isolated C1, C2, C3 fractures, any C1-C3 fracture, any C4-C7 fracture, two-level fractures, subluxation/dislocations, and transverse foramen (TF) fractures. Three studies were included in the meta-analysis for C1, C2, C1-C3, subluxations/dislocations, and TF fractures. Two studies were included in the meta-analysis for C3, C4-C7, and two-level fractures. The pooled odds ratio with 95% confidence interval for: C1 fractures and BCVI is 1.3 (0.8-2.1); C2: 1.6 (0.9-2.8); C3: 1.8 (0.9-3.6); C1-C3: 2.2 (1.1-4.2); C4-C7: 0.7 (0.3-1.7); Two-level: 2.5 (1.4-4.6); Subluxation/Dislocation: 2.9 (1.8-4.5); TF: 3.6 (1.4-8.9). DISCUSSION/CONCLUSION: This study found that when utilizing CTA for screening of BCVI only fractures in the C1-C3 region, two-level fractures, subluxations/dislocations, and transverse foramen fractures were associated with increased incidence of a BCVI. Further refinement of protocols for CTA in the setting of blunt cervical trauma may help limit unnecessary patient harm from overtreatment and reduce healthcare costs.

Changes in knee kinematics from applied external Tibial torque: Implications for stabilizing an anterior cruciate ligament deficient knee.

BACKGROUND: Changes in knee kinematics from internal tibial torque under tibiofemoral compression force have been studied, but the potentially stabilizing effects of external tibial torque have not been reported. We hypothesized that for a given knee flexion angle, 1) external torque would significantly reduce anterior tibial translation, internal tibial rotation, and valgus tibial rotation before and after sectioning the anterior cruciate ligament and 2) changes in kinematics from applied external torque would be significantly greater with the cruciate cut. METHODS: A robotic test system was used to flex intact human knees continuously from 0° to 50° under 200 N compression, without and with 5 Nm external torque. Tests were repeated after cruciate section. FINDINGS: With the cruciate intact, external torque had no significant effect on anterior translation, and significantly reduced internal and valgus rotations at all flexion angles. With the cruciate cut, external torque significantly reduced anterior translation beyond 25° flexion, significantly reduced internal rotation at all flexion angles, and significantly reduced valgus rotation beyond 15° flexion. Although external torque had no significant effect on anterior translation with the ACL intact, external torque produced relatively large decreases in anterior translation with the cruciate sectioned (-11.6 mm at 50° flexion). Reductions in valgus rotation from applied external torque were significantly greater for cruciate deficient knees beyond 25° flexion. INTERPRETATION: We conclude that external tibial torque may be important for controlling the abnormal kinematics associated with an anterior cruciate ligament deficient knee, and possibly help stabilize the knee during in vivo activities.

Website evaluation for shoulder and elbow fellowships in the United States: an evaluation of accessibility and content.

HYPOTHESIS AND/OR BACKGROUND: When examining the access and content related to shoulder and elbow fellowship websites, only 64% of programs had individual websites in a query performed 5 years earlier. The purpose of this study was to re-evaluate content about individual programs listed on the American Shoulder and Elbow Surgeons (ASES) website and on individual program websites and compare the results to prior data. METHODS: The ASES website was accessed to determine both the number of ASES-recognized shoulder and elbow fellowships and the number of direct links to fellowship program websites. A Google search was also performed to determine the ease of access to fellowship program websites. Each website was then evaluated for content in regard to their recruitment and educational program. RESULTS: The ASES website includes contact information and a brief description for 29 programs with 40 reported positions. When trying to identify links to program websites, there were functioning links to 6 programs (21%) and absent/nonfunctioning links for the remaining 23 (79%). Through a Google search, there were functioning links to 22 (76%) and absent/nonfunctioning links for 7 (24%) programs. All 29 program websites had faculty listing and program contact info whereas 28 (97%) had a description of their program. In terms of educational content, 17 (59%) included description of operative cases and 18 (62%) had descriptions of rotations/curriculum. DISCUSSION AND/OR CONCLUSION: Individual shoulder and elbow fellowship program websites provide varied content and accessibility. In the intervening 5 years, there has been minimal improvement in the accessibility of individual fellowship websites from the ASES website.

Femoral Contact Forces in the Anterior Cruciate Ligament Deficient Knee: A Robotic Study.

PURPOSE: To measure contact forces (CFs) at standardized locations representative of clinical articular cartilage defects on the medial and lateral femoral condyles during robotic tests with simulated weightbearing knee flexion. METHODS: Eleven human knees had 20-mm-diameter cylinders of native bone/cartilage cored from both femoral condyles at standardized locations, with each cylinder attached to a custom-built load cell that maintained the plug in its precise anatomic position. A robotic test system was used to flex the knee from 0° to 50° under 200-N tibiofemoral compression without and with a 2 Nm internal tibial torque, 5 Nm external tibial torque, and 45 N anterior tibial force (AF). CFs and knee kinematics were recorded before and after cutting the anterior cruciate ligament (ACL). RESULTS: ACL sectioning did not significantly increase medial or lateral CFs for any loading condition, with the exception of AF, in which increases in medial CF ranged from 38 N (at 15° flexion, P < .01) to 77 N (at 50° flexion, P < .002). Compared with the intact condition, ACL sectioning significantly increased anterior tibial translation by 12.33 mm (at 15° flexion, P < .001) and 17.4 mm (at 50° flexion, P < .001), and increased valgus rotation by 2.4° (at 15° flexion, P < .001) and 3.8° (at 50° flexion, P < .001). CONCLUSIONS: Our hypothesis that CF would increase after ACL section was confirmed for the AF test condition only, and only for the medial condyle beyond 10° flexion. With the ACL sectioned, it appeared that the increased CF was owing to the medial condyle riding up over the posterior tibial plateau resulting from the large anterior tibial displacements. CLINICAL RELEVANCE: Aside from our limited finding with AF, we concluded that CFs were generally unaffected by ACL section.

Contact force between the tibial spine and medial femoral condyle: A biomechanical study.

BACKGROUND: Contact between the tibial spine and medial femoral condyle with internal tibial rotation (ITR) has been proposed as a factor for the development of osteochondritis dissecans lesions. We hypothesized that tibial spine contact force (CF) would increase significantly with applied internal tibial torque (IT). METHODS: A 20 mm diameter cylinder of bone encompassing the tibial spine was cored and attached to a load cell. The isolated bone cylinder included the tibial attachments of the anterior cruciate ligament (ACL) and anterior horn of the lateral meniscus (AHLM). Eleven human cadaveric knees were flexed from 0°-50° under 200 N of tibiofemoral compression (TFC), without and with 2 N-m IT. Tests were repeated with the AHLM cut, and again with both AHLM and ACL cut, where the load cell recorded CF alone without contributions from any ligamentous attachments. FINDINGS: There were no significant differences in CF, ITR, or valgus tibial rotation (VTR) after sectioning the AHLM, without or with applied IT. With no tibial torque, mean CFs were less than 20 N throughout the flexion range. Addition of IT significantly increased 1) mean CF by 44.4 N(SD 15.8 N) at 0°(+240%) and 27.2 N(SD 5.0 N) at 20°(+675%), 2), mean ITR by 10.2°(SD 0.8°) at 0° flexion and 18.6°(SD 2.0°) at 20° flexion, and 3) mean VTR by 1.3°(SD 0.4°) at 0° flexion and 4.4°(SD 0.8°) at 20° flexion. INTERPRETATION: Our hypothesis was confirmed only between 0° and 20° of knee flexion, where the intercondylar separation distance is relatively small and the possibility of tibial spine contact with ITR is greater.

Differences in the Radius of Curvature Between Femoral Condyles: Implications for Osteochondral Allograft Matching.

BACKGROUND: The radius of curvature (ROC) is an important variable related to potential cartilage incongruities in the transplantation of a large femoral osteochondral allograft. The anterior-posterior length (APL) of a condyle is used as a criterion for donor-graft acceptance. We hypothesized that there would be a linear correlation between the ROC and APL of a condyle, that the ROC and APL would differ significantly between the medial femoral condyle (MFC) and the lateral femoral condyle (LFC), and that a donor graft from the LFC would be suitable for an MFC defect. METHODS: Knee magnetic resonance imaging scans of 147 patients with no cartilage defects were analyzed. Best-fit circles in the sagittal plane were determined at standardized locations on each condyle. Assuming the use of a 20-mm graft that was flush to the edges of the native cartilage, the central graft prominence was calculated for potential donor-host differences in the ROC. RESULTS: There was a linear correlation between the ROC and APL. There were significant differences in the mean ROC and APL between the MFC and LFC. Based on calculations of the central graft prominence among all ROC combinations within the patient group, 100% of potential medial-to-medial, 97.8% of lateral-to-lateral, and 92.5% of lateral-to-medial transplantations would produce a central graft prominence of <1 mm. On average, an allograft harvested from an LFC (mean ROC, 25.7 mm; mean APL, 69.8 mm) implanted into an MFC defect site (mean ROC, 31.9 mm; mean APL, 66.6 mm) would have a central graft prominence of 0.4 ± 0.3 mm. CONCLUSIONS: Assuming a maximum central graft prominence tolerance of +1 mm, our findings demonstrate that matching the ROC or APL would not be necessary for potential medial-to-medial or lateral-to-lateral allograft transplants within this patient group. Implantation of an LFC donor allograft into an MFC defect is also supported by our findings.

Effects of Proud Large Osteochondral Plugs on Contact Forces and Knee Kinematics: A Robotic Study.

BACKGROUND: Osteochondral allograft (OCA) transplantation is used to treat large focal femoral condylar articular cartilage defects. A proud plug could affect graft survival by altering contact forces (CFs) and knee kinematics. HYPOTHESIS: A proud OCA plug will significantly increase CF and significantly alter knee kinematics throughout controlled knee flexion. STUDY DESIGN: Controlled laboratory study. METHODS: Human cadaver knees had miniature load cells, each with a 20-mm-diameter cylinder of native bone/cartilage attached at its exact anatomic position, installed in both femoral condyles at standardized locations representative of clinical defects. Spacers were inserted to create proud plug conditions of +0.5, +1.0, and +1.5 mm. CFs and knee kinematics were recorded as a robot flexed the knee continuously from 0° to 50° under 1000 N of tibiofemoral compression. RESULTS: CFs were increased significantly (vs flush) for all proudness conditions between 0° and 45° of flexion (medial) and 0° to 50° of flexion (lateral). At 20°, the average increases in medial CF for +0.5-mm, +1-mm, and +1.5-mm proudness were +80 N (+36%), +155 N (+70%), and +193 N (+87%), respectively. Corresponding increases with proud lateral plugs were +44 N (+14%), +90 N (+29%), and +118 N (+38%). CF increases for medial plugs at 20° of flexion were significantly greater than those for lateral plugs at all proudness conditions. At 50°, a 1-mm proud lateral plug significantly decreased internal tibial rotation by 15.4° and decreased valgus rotation by 2.5°. CONCLUSION: A proud medial or lateral plug significantly increased CF between 0° and 45° of flexion. Our results suggest that a medial plug at 20° may be more sensitive to graft incongruity than a lateral plug. The changes in rotational kinematics with proud lateral plugs were attributed to earlier contact between the proud plug's surface and the lateral meniscus, leading to rim impingement with decreased tibial rotation. CLINICAL RELEVANCE: Increased CF and altered knee kinematics from a proud femoral plug could affect graft viability. Plug proudness of only 0.5 mm produced significant changes in CF and knee kinematics, and the clinically accepted 1-mm tolerance may need to be reexamined in view of our findings.

Contact Forces Acting on Large Femoral Osteochondral Allografts During Forced Knee Extension.

BACKGROUND: A single cylindrical graft plug is commonly used for large focal femoral defects during osteochondral allograft (OCA) transplantation. Excessive contact force (CF) on a proud plug could compromise initial healing. CFs during forced knee extension are of particular interest because this maneuver is used by therapists to restore early postoperative range of motion. HYPOTHESIS: A proud OCA plug will significantly increase the CF and significantly decrease the knee extension angle (KEA). STUDY DESIGN: Controlled laboratory study. METHODS: Eleven human knee specimens had miniature load cells installed in both femoral condyles at standardized locations representative of clinical defects. Each load cell had a 20-mm-diameter cylinder of native bone/cartilage attached at its precise anatomic location. Four spacers, 0.5 mm in thickness, were inserted sequentially between each load cell and its mounting bracket to create proud plug conditions of 0.5 to 2 mm. Measurements of the CF and KEA were recorded at extension moment levels up to 8 N·m. RESULTS: At 8 N·m, the mean CFs for flush plugs were 149 ± 18 N (lateral) and 34 ± 13 N (medial). The mean increases in the medial CF (compared with flush) for 0.5-mm, 1-mm, 1.5-mm, and 2-mm proud conditions were 31 N (+91%), 64 N (+188%), 111 N (+325%), and 154 N (+451%), respectively. Corresponding increases for lateral proud plugs were 55 N (+37%), 120 N (+81%), 162 N (+109%), and 210 N (+141%), respectively. The CFs (and CF increases) for lateral grafts were significantly ( P < .05) higher than corresponding values for medial grafts at each proudness condition. Medial plug proudness had no consistent effect on the KEA. A 1-mm proud lateral plug significantly reduced the KEA by -1.6° (0 N·m) and -0.9° (2 N·m). CONCLUSION: Graft proudness of only 0.5 mm significantly increased CFs during forced knee extension, emphasizing the surgical precision necessary to achieve normal CF levels. CLINICAL RELEVANCE: It is believed that some amount of CF is beneficial in the early stages of graft healing, and our findings suggest that forced knee extension may be well suited for this purpose. However, the surgeon should be aware that large extension moments can also generate relatively high CFs, especially if the plug is proud.