How dimensions can guide surgical planning and training: a systematic review of Kambin's triangle.

OBJECTIVE: The authors sought to analyze the current literature to determine dimensional trends across the lumbar levels of Kambin's triangle, clarify the role of imaging techniques for preoperative planning, and understand the effect of inclusion of the superior articular process (SAP). This compiled knowledge of the triangle is needed to perform successful procedures, reduce nerve root injuries, and help guide surgeons in training. METHODS: The authors performed a search of multiple databases using combinations of keywords: Kambin's triangle, size, measurement, safe triangle, and bony triangle. Articles were included if their main findings included measurement of Kambin's triangle. The PubMed, Scopus, Ovid, Cochrane, Embase, and Medline databases were systematically searched for English-language articles with no time frame restrictions through July 2022. RESULTS: Eight studies comprising 132 patients or cadavers were included in the study. The mean ± SD age was 66.69 ± 9.6 years, and 53% of patients were male. Overall, the size of Kambin's triangle increased in area moving down vertebral levels, with L5-S1 being the largest (133.59 ± 4.36 mm2). This trend followed a linear regression model when SAP was kept (p = 0.008) and removed (p = 0.003). There was also a considerable increase in the size of Kambin's triangle if the SAP was removed. CONCLUSIONS: Here, the authors have provided the first reported systematic review of the literature of Kambin's triangle, its measurements at each lumbar level, and key areas of debate related to the definition of the working safe zone. These findings indicate that CT is heavily utilized for imaging of the safe zone, the area of Kambin's triangle tends to increase caudally, and variation exists between patients. Future studies should focus on using advanced imaging techniques for preoperative planning and establishing guidelines for surgeons.

"The eye sees only what the mind is prepared to comprehend": Unrecognized incidental findings on intraoperative computed tomography during spine instrumentation surgery.

BACKGROUND: Intraoperative computed tomography (CT) is becoming more widely utilized in spine fusion surgeries. The use of CT-based image guidance has been shown to increase the accuracy in instrumentation placement and to reduce the rate of reoperation. However, incidental findings that are obvious in retrospect are still missed in spinal fusion surgeries due to the concept of inattentional blindness and surgeons' preoccupation with the main objective of intraoperative CT (i.e. instrumentation accuracy). CASE DESCRIPTION: The first case describes a 60-year-old male who underwent posterior spinal laminectomy and interbody fusions from L2-L5. Intraoperative CT confirmed appropriate placement of hardware. However, when he was transferred out to the care unit and extubated, he developed a severe headache for which the source was confirmed to be a pneumocephalus from durotomy and cerebrospinal fluid leakage on repeat CT. A retrospective review of his intraoperative CT demonstrated the intrathecal air at L5-S1 interlaminar space that was missed on evaluation during surgery. The second case describes a 68-year-old female who was treated with a successful T4 to pelvis instrumentation and fusion with vertebral column resection at T10 confirmed with imaging. Postoperatively, she developed rapidly progressive oxygen desaturation and was found to have a pneumothorax which had been present on the intraoperative imaging. CONCLUSION: This case report of two patients with missed intraoperative findings demonstrates the importance of looking beyond instrumentation placement and evaluating the entire intraoperative CT imaging to find abnormalities that could complicate the patients' postoperative recovery and overall hospital stay.

Incidence of Congenital Spinal Abnormalities Among Pediatric Patients and Their Association With Scoliosis and Systemic Anomalies.

BACKGROUND: Congenital abnormalities when present, according to VACTERL theory, occur nonrandomly with other congenital anomalies. This study estimates the prevalence of congenital spinal anomalies, and their concurrence with other systemic anomalies. METHODS: A retrospective cohort analysis on Health care Cost and Utilization Project's Kids Inpatient Database (KID), years 2000, 2003, 2006, 2009 was performed. ICD-9 coding identified congenital anomalies of the spine and other body systems. OUTCOME MEASURES: Overall incidence of congenital spinal abnormalities in pediatric patients, and the concurrence of spinal anomaly diagnoses with other organ system anomalies. Frequencies of congenital spine anomalies were estimated using KID hospital-and-year-adjusted weights. Poisson distribution in contingency tables tabulated concurrence of other congenital anomalies, grouped by body system. RESULTS: Of 12,039,432 patients, rates per 100,000 cases were: 9.1 hemivertebra, 4.3 Klippel-Fiel, 56.3 Chiari malformation, 52.6 tethered cord, 83.4 spina bifida, 1.2 absence of vertebra, and 6.2 diastematomyelia. Diastematomyelia had the highest concurrence of other anomalies: 70.1% of diastematomyelia patients had at least one other congenital anomaly. Next, 63.2% of hemivertebra, and 35.2% of Klippel-Fiel patients had concurrent anomalies. Of the other systems deformities cooccuring, cardiac system had the highest concurrent incidence (6.5% overall). In light of VACTERL's definition of a patient being diagnosed with at least 3 VACTERL anomalies, hemivertebra patients had the highest cooccurrence of ≥3 anomalies (31.3%). With detailed analysis of hemivertebra patients, secundum ASD (14.49%), atresia of large intestine (10.2%), renal agenesis (7.43%) frequently cooccured. CONCLUSIONS: Congenital abnormalities of the spine are associated with serious systemic anomalies that may have delayed presentations. These patients continue to be at a very high, and maybe higher than previously thought, risk for comorbidities that can cause devastating perioperative complications if not detected preoperatively, and full MRI workups should be considered in all patients with spinal abnormalities. LEVEL OF EVIDENCE: Level III.

Comparison of helicopter versus ground transport for the interfacility transport of isolated spinal injury.

BACKGROUND CONTEXT: The use and need of helicopter aeromedical transport systems (HEMSs) in health care today is based on the basic belief that early definitive care improves outcomes. Helicopter aeromedical transport system is perceived to be safer than ground transport (GT) for the interfacility transfer of patients who have sustained spinal injury because of the concern for deterioration of neurologic function if there is a delay in reaching a higher level of care. However, the use of HEMS is facing increasing public scrutiny because of its significantly greater cost and unique risk profile. PURPOSE: The aim of the study was to determine whether GT for interfacility transfer of patients with spinal injury resulted in less favorable clinical outcomes compared with HEMS. STUDY DESIGN/SETTING: Retrospective review of all patients transferred to a Level 1 trauma center. PATIENT SAMPLE: Patients identified from the State Trauma Registry who were initially seen at another hospital with an isolated diagnosis of injury to the spine and then transferred to a Level 1 trauma center over a 2-year period. OUTCOME MEASURES: Neurologic deterioration, disposition from the emergency department, in-hospital mortality, interfacility transfer time, hospital length of stay, nonroutine discharge, and radiographic evidence of worsening spinal injury. METHODS: Patients with International Classification of Diseases, Ninth Revision (ICD-9) codes for injury to the spine were selected and records were reviewed for demographics and injury details. All available spine radiographs were reviewed by an orthopedic surgeon blinded to clinical data and transport type. Chi-square and t tests and multivariate linear and logistic regression models were done using STATA version 10. RESULTS: A total of 274 spine injury patients were included in our analysis, 84 (31%) of whom were transported by HEMS and 190 (69%) by GT. None of the GT patients had any deterioration in neurologic examination nor any detectable alteration in the radiographic appearance of their spine injury attributable to the transportation process. Helicopter aeromedical transport system resulted in significantly less transfer time with an average time of 80 minutes compared with 112 minutes with GT (p<.001). Ultimate disposition included 175 (64%) patients discharged to home, 15 (5%) expired patients, and 84 (31%) discharged to extended care facilities. After adjusting for patient age and Injury Severity Score, the use of GT was not a significant predictor of in-hospital mortality (odds ratio, 1.4; 95% confidence interval, 0.3-5), hospital length of stay (11.2+1.3 vs. 9.5+0.8 days, p=.3), or nonroutine discharge (odds ratio, 1.1; 95% confidence interval, 0.5-2.2). CONCLUSIONS: Ground transport for interfacility transfer of patients with spinal injury appears to be safe and suitable for patients who lack other compelling reasons for HEMS. A prospective analysis of transportation mode in a larger cohort of patients is needed to verify our findings.

Central versus lower body obesity distribution and the association with lower limb physical function and disability.

OBJECTIVE: To determine whether fat distribution in obese adults is significantly associated with decreased function and increased disability. DESIGN: Cross-sectional epidemiologic analysis. SETTING: Multicenter, community-based study. PARTICIPANTS: Multicenter Osteoarthritis Study participants included adults ages 50-79 years at high risk of developing or already possessing knee osteoarthritis. A total of 549 men and 892 women from the Multicenter Osteoarthritis Study who had a body mass index ≥ 30 kg/m² and who underwent dual energy x-ray absorptiometry (DEXA) scans were included in these analyses. Exclusion criteria included bilateral knee replacements, cancer, or other rheumatologic disease. METHODS: Body fat distribution was determined using baseline DEXA scan data. A ratio of abdominal fat in grams compared with lower limb fat in grams (trunk:lower limb fat ratio) was calculated. Participants were divided into quartiles of trunk:lower limb fat ratio, with highest and lowest quartiles representing central and lower body obesity, respectively. Backward elimination linear regression models stratified by gender were used to analyze statistical differences in function and disability between central and lower body obesity groups. MAIN OUTCOME MEASURES: Lower limb physical function measures included 20-meter walk time, chair stand time, and peak knee flexion and extension strength. Disability was assessed using the Late Life Function and Disability Index. RESULTS: Trunk:lower limb fat ratio was not significantly associated with physical function or disability in women or men (P value .167-.972). Total percent body fat (standardized ß = -0.1533 and -0.1970 in men and women, respectively) was a better predictor of disability when compared with trunk:lower limb fat ratio (standardized ß = 0.0309 and 0.0072). CONCLUSIONS: Although fat distribution patterns may affect clinical outcomes in other areas, lower limb physical function and disability do not appear to be significantly influenced by the distribution of fat in obese older adults with, or at risk for, knee osteoarthritis. These data do not support differential treatment of functional limitations based on fat distribution.

Effects of concurrent use of an ankle support with a laterally wedged insole for medial knee osteoarthritis.

OBJECTIVE: To determine the biomechanical and symptomatic effects of concurrent use of an ankle support and a laterally wedged insole on adults with symptomatic medial compartment knee osteoarthritis. DESIGN: Randomized, crossover clinical trial. SETTING: Outpatient gait analysis laboratory. PARTICIPANTS: Fourteen adults, mean age 51.9 +/- 8.3 years, with symptomatic medial compartment knee osteoarthritis and no previous lower-limb surgeries or history of wedged insole use were recruited through a radiology database and phone screen. INTERVENTIONS: Subjects were randomized to use a laterally wedged insole before (n = 8) or after (n = 6) use of the insole with an ankle support for 2 weeks. MAIN OUTCOME MEASURES: Lower-limb alignment by radiographic hip-knee-ankle angle, talocalcaneal, and talar tilt angles; medial compartment loading by the external knee adduction moment; and pain by visual analog scale and the Knee Osteoarthritis Outcome Score pain subscale. RESULTS: There were no differences between groups for age, gender, body mass index, baseline knee pain, or alignment. Augmentation of the wedged insole with the ankle supporter did not result in any significant changes in lower-limb alignment or external knee adduction moment. Intergroup crossover comparisons demonstrated a 10.5-point greater average improvement in Knee Osteoarthritis Outcome Score pain subscale (P < .011) and a trend towards a 10.2-point improvement in the Activities of Daily Living subscale (P < .055) with the wedged insole alone in comparison with concurrent use of the ankle support with the wedged insole. CONCLUSION: Concurrent use of an ankle support did not appear to improve the effects of a laterally wedged insole on lower-limb mechanical alignment or medial compartment loading. Improved pain and activities of daily living with use of the wedged insole alone suggests that use of an ankle support may attenuate clinical benefit.