The Influence of Comminution and Posterior Ligamentous Complex Integrity on Treatment Decision Making in Thoracolumbar Burst Fractures Without Neurologic Deficit?

STUDY DESIGN

A prospective study.

OBJECTIVE

to evaluate the impact of vertebral body comminution and Posterior Ligamentous Complex (PLC) integrity on the treatment recommendations of thoracolumbar fractures among an expert panel of 22 spine surgeons.

METHODS

A review of 183 prospectively collected thoracolumbar burst fracture computed tomography (CT) scans by an expert panel of 22 trauma spine surgeons to assess vertebral body comminution and PLC integrity. This study is a sub-study of a prospective observational study of thoracolumbar burst fractures (Spine TL A3/A4). Each expert was asked to grade the degree of comminution and certainty about the PLC disruption from 0 to 100, with 0 representing the intact vertebral body or intact PLC and 100 representing complete comminution or complete PLC disruption, respectively.

RESULTS

≥45% comminution had a 74% chance of having surgery recommended, while <25% comminution had an 86.3% chance of non-surgical treatment. A comminution from 25 to 45% had a 57% chance of non-surgical management. ≥55% PLC injury certainity had a 97% chance of having surgery, and ≥45-55% PLC injury certainty had a 65%. <20% PLC injury had a 64% chance of having non-operative treatment. A 20 to 45% PLC injury certainity had a 56% chance of non-surgical management. There was fair inter-rater agreement on the degree of comminution (ICC .57 [95% CI 0.52-.63]) and the PLC integrity (ICC .42 [95% CI 0.37-.48]).

CONCLUSION

The study concludes that vetebral comminution and PLC integrity are major dterminant in decision making of thoracolumbar fractures without neurological deficit. However, more objective, reliable, and accurate methods of assessment of these variables are warranted.

Predictive Algorithm for Surgery Recommendation in Thoracolumbar Burst Fractures Without Neurological Deficits

STUDY DESIGN

Predictive algorithm via decision tree.

OBJECTIVES

Artificial intelligence (AI) remain an emerging field and have not previously been used to guide therapeutic decision making in thoracolumbar burst fractures. Building such models may reduce the variability in treatment recommendations. The goal of this study was to build a mathematical prediction rule based upon radiographic variables to guide treatment decisions.

METHODS

Twenty-two surgeons from the AO Knowledge Forum Trauma reviewed 183 cases from the Spine TL A3/A4 prospective study (classification, degree of certainty of posterior ligamentous complex (PLC) injury, use of M1 modifier, degree of comminution, treatment recommendation). Reviewers' regions were classified as Europe, North/South America and Asia. Classification and regression trees were used to create models that would predict the treatment recommendation based upon radiographic variables. We applied the decision tree model which accounts for the possibility of non-normal distributions of data. Cross-validation technique as used to validate the multivariable analyses.

RESULTS

The accuracy of the model was excellent at 82.4%. Variables included in the algorithm were certainty of PLC injury (%), degree of comminution (%), the use of M1 modifier and geographical regions. The algorithm showed that if a patient has a certainty of PLC injury over 57.5%, then there is a 97.0% chance of receiving surgery. If certainty of PLC injury was low and comminution was above 37.5%, a patient had 74.2% chance of receiving surgery in Europe and Asia vs 22.7% chance in North/South America. Throughout the algorithm, the use of the M1 modifier increased the probability of receiving surgery by 21.4% on average.

CONCLUSION

This study presents a predictive analytic algorithm to guide decision-making in the treatment of thoracolumbar burst fractures without neurological deficits. PLC injury assessment over 57.5% was highly predictive of receiving surgery (97.0%). A high degree of comminution resulted in a higher chance of receiving surgery in Europe or Asia vs North/South America. Future studies could include clinical and other variables to enhance predictive ability or use machine learning for outcomes prediction in thoracolumbar burst fractures.

Understanding Decision Making as It Influences Treatment in Thoracolumbar Burst Fractures Without Neurological Deficit: Conceptual Framework and Methodology

STUDY DESIGN

This paper presents a description of a conceptual framework and methodology that is applicable to the manuscripts that comprise this focus issue.

OBJECTIVES

Our goal is to present a conceptual framework which is relied upon to better understand the processes through which surgeons make therapeutic decisions around how to treat thoracolumbar burst fractures (TL) fractures.

METHODS

We will describe the methodology used in the AO Spine TL A3/4 Study prospective observational study and how the radiographs collected for this study were utilized to study the relationships between various variables that factor into surgeon decision making.

RESULTS

With 22 expert spine trauma surgeons analyzing the acute CT scans of 183 patients with TL fractures we were able to perform pairwise analyses, look at reliability and correlations between responses and develop frequency tables, and regression models to assess the relationships and interactions between variables. We also used machine learning to develop decision trees.

CONCLUSIONS

This paper outlines the overall methodological elements that are common to the subsequent papers in this focus issue.

Interobserver Reliability in the Classification of Thoracolumbar Fractures Using the AO Spine TL Injury Classification System Among 22 Clinical Experts in Spine Trauma Care

STUDY DESIGN

Reliability study utilizing 183 injury CT scans by 22 spine trauma experts with assessment of radiographic features, classification of injuries and treatment recommendations.

OBJECTIVES

To assess the reliability of the AOSpine TL Injury Classification System (TLICS) including the categories within the classification and the M1 modifier.

METHODS

Kappa and Intraclass correlation coefficients were produced. Associations of various imaging characteristics (comminution, PLC status) and treatment recommendations were analyzed through regression analysis. Multivariable logistic regression modeling was used for making predictive algorithms.

RESULTS

Reliability of the AO Spine TLICS at differentiating A3 and A4 injuries (N = 71) (K = .466; 95% CI .458 - .474; P < .001) demonstrated moderate agreement. Similarly, the average intraclass correlation coefficient (ICC) amongst A3 and A4 injuries was excellent (ICC = .934; 95% CI .919 - .947; P < .001) and the ICC between individual measures was moderate (ICC = .403; 95% CI .351 - .461; P < .001). The overall agreement on the utilization of the M1 modifier amongst A3 and A4 injuries was fair (K = .161; 95% CI .151 - .171; P < .001). The ICC for PLC status in A3 and A4 injuries averaged across all measures was excellent (ICC = .936; 95% CI .922 - .949; P < .001). The M1 modifier suggests respondents are nearly 40% more confident that the PLC is injured amongst all injuries. The M1 modifier was employed at a higher frequency as injuries were classified higher in the classification system.

CONCLUSIONS

The reliability of surgeons differentiating between A3 and A4 injuries in the AOSpine TLICS is substantial and the utilization of the M1 modifier occurs more frequently with higher grades in the system.

Using Equipoise to Determine the Radiographic Characteristics Leading to Agreement on Best Treatment for Thoracolumbar Burst Fractures Without Neurologic Deficits

STUDY DESIGN

Retrospective analysis of prospectively collected data.

OBJECTIVES

Our goal was to assess radiographic characteristics associated with agreement and disagreement in treatment recommendation in thoracolumbar (TL) burst fractures.

METHODS

A panel of 22 AO Spine Knowledge Forum Trauma experts reviewed 183 cases and were asked to: (1) classify the fracture; (2) assess degree of certainty of PLC disruption; (3) assess degree of comminution; and (4) make a treatment recommendation. Equipoise threshold used was 77% (77:23 distribution of uncertainty or 17 vs 5 experts). Two groups were created: consensus vs equipoise.

RESULTS

Of the 183 cases reviewed, the experts reached full consensus in only 8 cases (4.4%). Eighty-one cases (44.3%) were included in the agreement group and 102 cases (55.7%) in the equipoise group. A3/A4 fractures were more common in the equipoise group (92.0% vs 83.7%, P < .001). The agreement group had higher degree of certainty of PLC disruption [35.8% (SD 34.2) vs 27.6 (SD 27.3), P < .001] and more common use of the M1 modifier (44.3% vs 38.3%, P < .001). Overall, the degree of comminution was slightly higher in the equipoise group [47.8 (SD 20.5) vs 45.7 (SD 23.4), P < .001].

CONCLUSIONS

The agreement group had a higher degree of certainty of PLC injury and more common use of M1 modifier (more type B fractures). The equipoise group had more A3/A4 type fractures. Future studies are required to identify the role of comminution in decision making as degree of comminution was slightly higher in the equipoise group.

Expert Opinion, Real-World Classification, and Decision-Making in Thoracolumbar Burst Fractures Without Neurologic Deficits?

STUDY DESIGN

Retrospective analysis of prospectively collected data.

OBJECTIVES

To compare decision-making between an expert panel and real-world spine surgeons in thoracolumbar burst fractures (TLBFs) without neurological deficits and analyze which factors influence surgical decision-making.

METHODS

This study is a sub-analysis of a prospective observational study in TL fractures. Twenty two experts were asked to review 183 CT scans and recommend treatment for each fracture. The expert recommendation was based on radiographic review.

RESULTS

Overall agreement between the expert panel and real-world surgeons regarding surgery was 63.2%. In 36.8% of cases, the expert panel recommended surgery that was not performed in real-world scenarios. Conversely, in cases where the expert panel recommended non-surgical treatment, only 38.6% received non-surgical treatment, while 61.4% underwent surgery. A separate analysis of A3 and A4 fractures revealed that expert panel recommended surgery for 30% of A3 injuries and 68% of A4 injuries. However, 61% of patients with both A3 and A4 fractures received surgery in the real world. Multivariate analysis demonstrated that a 1% increase in certainty of PLC injury led to a 4% increase in surgery recommendation among the expert panel, while a .2% increase in the likelihood of receiving surgery in the real world.

CONCLUSION

Surgical decision-making varied between the expert panel and real-world treating surgeons. Differences appear to be less evident in A3/A4 burst fractures making this specific group of fractures a real challenge independent of the level of expertise.

The AO Spine Thoracolumbar Injury Classification System and Treatment Algorithm in Decision Making for Thoracolumbar Burst Fractures Without Neurologic Deficit

STUDY DESIGN

Prospective Observational Study.

OBJECTIVE

To determine the alignment of the AO Spine Thoracolumbar Injury Classification system and treatment algorithm with contemporary surgical decision making.

METHODS

183 cases of thoracolumbar burst fractures were reviewed by 22 AO Spine Knowledge Forum Trauma experts. These experienced clinicians classified the fracture morphology, integrity of the posterior ligamentous complex and degree of comminution. Management recommendations were collected.

RESULTS

There was a statistically significant stepwise increase in rates of operative management with escalating category of injury (P < .001). An excellent correlation existed between recommended expert management and the actual treatment of each injury category: A0/A1/A2 (OR 1.09, 95% CI 0.70-1.69, P = .71), A3/4 (OR 1.62, 95% CI 0.98-2.66, P = .58) and B1/B2/C (1.00, 95% CI 0.87-1.14, P = .99). Thoracolumbar A4 fractures were more likely to be surgically stabilized than A3 fractures (68.2% vs 30.9%, P < .001). A modifier indicating indeterminate ligamentous injury increased the rate of operative management when comparing type B and C injuries to type A3/A4 injuries (OR 39.19, 95% CI 20.84-73.69, P < .01 vs OR 27.72, 95% CI 14.68-52.33, P < .01).

CONCLUSIONS

The AO Spine Thoracolumbar Injury Classification system introduces fracture morphology in a rational and hierarchical manner of escalating severity. Thoracolumbar A4 complete burst fractures were more likely to be operatively managed than A3 fractures. Flexion-distraction type B injuries and translational type C injuries were much more likely to have surgery recommended than type A fractures regardless of the M1 modifier. A suspected posterior ligamentous injury increased the likelihood of surgeons favoring surgical stabilization.

The Diagnostic Process of Spinal Post-traumatic Deformity: An Expert Survey of 7 Cases, Consensus on Clinical Relevance Does Exist

STUDY DESIGN

Survey of cases.

OBJECTIVE

To evaluate the opinion of experts in the diagnostic process of clinically relevant Spinal Post-traumatic Deformity (SPTD).

SUMMARY OF BACKGROUND DATA

SPTD is a potential complication of spine trauma that can cause decreased function and quality of life impairment. The question of when SPTD becomes clinically relevant is yet to be resolved.

METHODS

The survey of 7 cases was sent to 31 experts. The case presentation was medical history, diagnostic assessment, evaluation of diagnostic assessment, diagnosis, and treatment options. Means, ranges, percentages of participants, and descriptive statistics were calculated.

RESULTS

Seventeen spinal surgeons reviewed the presented cases. The items' fracture type and complaints were rated by the participants as more important, but no agreement existed on the items of medical history. In patients with possible SPTD in the cervical spine (C) area, participants requested a conventional radiograph (CR) (76%-83%), a flexion/extension CR (61%-71%), a computed tomography (CT)-scan (76%-89%), and a magnetic resonance (MR)-scan (89%-94%). In thoracolumbar spine (ThL) cases, full spine CR (89%-100%), CT scan (72%-94%), and MR scan (65%-94%) were requested most often. There was a consensus on 5 out of 7 cases with clinically relevant SPTD (82%-100%). When consensus existed on the diagnosis of SPTD, there was a consensus on the case being compensated or decompensated and being symptomatic or asymptomatic.

CONCLUSIONS

There was strong agreement in 5 out of 7 cases on the presence of the diagnosis of clinically relevant SPTD. Among spine experts, there is a strong consensus to use CT scan and MR scan, a cervical CR for C-cases, and a full spine CR for ThL-cases. The lack of agreement on items of the medical history suggests that a Delphi study can help us reach a consensus on the essential items of clinically relevant SPTD.

LEVEL OF EVIDENCE

Level V.

Preoperative pain sensitivity predicts postoperative pain severity and analgesics requirement in lumbar fusion surgery - a prospective observational study

BACKGROUND CONTENT

The goal of postoperative pain management is to facilitate the patient's return to normal activity and decrease the detrimental effects of acute postsurgical pain. In order to provide more tailored and successful pain treatment, it is necessary to identify individuals who are at a high risk of experiencing severe postoperative pain. The most precise way to assess pain sensitivity is by determining the pressure pain threshold and heat pain threshold by objective methods using a digital algometer and neurotouch respectively.

PURPOSE

The primary aim of the study is to assess the preoperative pain threshold and its influence on postoperative pain severity and analgesics requirements in patients undergoing lumbar fusion surgeries.

STUDY DESIGN

Prospective, observational study.

PATIENT SAMPLE

Sixty patients requiring a single-level lumbar fusion surgery.

OUTCOME MEASURES

Postoperative pain intensity and the amount of postoperative analgesics consumption.

METHODS

In our patients, preoperative pain sensitivity was assessed by pressure pain threshold measurements with the help of a digital algometer, and heat pain threshold using a neurotouch instrument. In addition, pain sensitivity questionnaires (PSQ) were used in all our patients to determine pain sensitivity. Preoperative psychosocial and functional assessments were performed by Hospital anxiety-depression scores (HADS), and Oswestry disability index (ODI) respectively. Preoperative visual analog scale (VAS) score was determined at three instances of needle prick (phlebotomy, glucometer blood sugar, and intradermal antibiotic test dose) and during the range of movements of the lumbar spine region. Postoperative VAS score and postoperative breakthrough analgesic requirements were recorded in all of these patients from day 0 to day 3.

RESULTS

The average age of the patients was 51.11±13.467 years and 70% were females. Females had lower mean algometry values (72.14±7.56) compared to males (77.34±6.33). Patients with higher HADS (p<.0016), higher PSQ (p<.001), higher ODI scores(p<.001), and female gender significantly correlated with a lower algometer average indicating high pain sensitivity. Patients with lower preoperative VAS scores and with higher neurotouch scores showed lower postoperative VAS scores at different time periods. Preoperative VAS scores, algometer average scores, neurotouch scores, and HADS scores were considered as independent variables (predictors) for postoperative VAS at 6 hours period. By the multivariate analysis, factors like preoperative VAS scores, algometer average scores, and HADS scores were statistically significant (p<.05). There was a significant correlation between algometer average scores (p<.001) with the breakthrough analgesics.

CONCLUSION

Preoperative assessment of pain sensitivity can predict postoperative analgesic requirements and aid in recovery. Patients with a lower pain threshold should be counseled preoperatively and also receive a better titration of analgesics perioperatively.

"Satellite pedicle screws" - A novel technique of pedicle screw insertion in obese patients undergoing lumbar fusion

The presence of thick sub-cutaneous fat and bulky paraspinal musculature mandates extensive surgical dissection in obese patients undergoing open Transforaminal lumbar interbody fusion surgery. Securing a 'converging' pedicle screw trajectory becomes difficult by the counterforces of the erector spinae muscles and thick sub-cutaneous fat in obese patients, especially at the L5-S1 level. We describe the use of a limited standard posterior midline exposure and a separate, far lateral 'satellite' incision to insert pedicle screws in an optimal trajectory in obese patients. Through proper pre-operative planning of the axial and sagittal MRI, the appropriate entry site is determined which is executed intra-operatively to insert pedicle screws freehand. Through a single 1.5 cm incision, both L5-S1 screws were inserted. Fourteen obese patients (mean BMI was 30.5 ± 1.1) received 56 satellite pedicle screws for TLIF at L5-S1 level. The mean age was 48.3 ± 9.7 years. The mean blood loss was 244.8 ± 114 ml and the mean operative time was 126.7 ± 82.8 min. In all patients, the screws were inserted as per pre-operative planning without any difficulties. All wounds healed well without wound complications. There were no screw related complications, and in the antero-posterior and lateral radiographs, there were no screw breaches. Satellite free-hand pedicle screws are safe and easily reproducible. They enable limited dissection of the main surgical wound and well-medialised converging pedicle screws in obese patients.

Spinal Post-traumatic Deformity: An International Expert Survey Among AO Spine Knowledge Forum Members

STUDY DESIGN

Survey among spine experts.

OBJECTIVE

To investigate the different views and opinions of clinically relevant spinal post-traumatic deformity (SPTD).

SUMMARY OF BACKGROUND DATA

There is no clear definition of clinically relevant SPTD. This leads to a wide variation in characteristics used for diagnosis and treatment indications of SPTD. To understand the current concepts of SPTD a survey was conducted among spine trauma surgeons.

METHODS

Members of the AO Spine Knowledge Forum Trauma participated in an online survey. The survey was divided in 4 domains: Demographics, criteria to define SPTD, risk factors, and management. The data were collected anonymously and analyzed using descriptive statistics, absolute, and relative frequencies. Consensus on dichotomous outcomes was set to 80% of agreement.

RESULTS

Fifteen members with extensive experience in treatment of spinal trauma participated, representing the 5 AO Spine Regions. Back pain was the only criterion for definition of SPTD with complete agreement. Consensus (≥80%) was reached for kyphotic angulation outside normative ranges and impaired function. Eighty-seven percent and 100% agreed that a full-spine conventional radiograph was necessary in diagnosing and treating SPTD, respectively. The "missed B-type injury" was rated at most important by all but 1 participant. There was no agreement on other risk factors leading to clinically relevant SPTD. Concerning the management, all participants agreed that an asymptomatic patient should not undergo surgical treatment and that neurological deficit is an absolute surgical indication. For most of the participants the preferred surgical treatment of acute injury in all spine regions but the subaxial region is posterior fixation.

CONCLUSION

Some consensus exists among leading experts in the field of spine trauma care concerning the definition, diagnosis, risk factors, and management of SPTD. This study acts as the foundation for a Delphi study among the global spine community.

Perioperative analgesic efficacy and safety of erector spinae plane block in posterior cervical spine surgery-a double blinded, randomized controlled study

BACKGROUND CONTENT

Posterior cervical spine surgery (PCSS) are typically open surgeries and entail significant postoperative pain. Current perioperative pain management in PCSS is reliant on multimodal analgesia. While perioperative epidural anesthetic infusion can be used in lumbar surgeries, this is not an option in the cervical spine. Pre-emptive regional analgesia through erector spinae plane block (ESPB) has shown significant perioperative analgesic benefits in lumbar spine surgeries. There are no such clinical studies in PCSS.

PURPOSE

To assess the safety and efficacy of ultrasound-guided ESPB for perioperative analgesia in PCSS.

STUDY DESIGN

Prospective, randomized controlled, double-blinded study.

PATIENT SAMPLE

Eighty-six patients requiring sub-axial PCSS with or without instrumentation were randomized into two groups, those who underwent ESPB with multimodal analgesia (case) and those with only multimodal analgesia (control).

OUTCOME MEASURES

Demographic and surgical data (blood loss, duration of surgery, perioperative total opioid consumption, muscle relaxants used) were assessed. Postoperatively, the surgical site pain, alertness scale, satisfaction score, time to mobilization and complications were recorded.

METHODS

After anesthesia and prone position, case patients received ultrasound-guided ESPB at the T1 level using 15 ml of 0.25% bupivacaine and 8 mg Dexamethasone bilaterally while the control patients received only standard postoperative multimodal analgesia.

RESULTS

There were 43 patients in each group; the two groups were identical in demographic and surgical profile. The intraoperative opioid consumption (119.53±40.35 vs. 308.6±189.78; p<.001) in mcg), muscle relaxant usage (50.00±0.00 mg vs. 59.53±3.75 mg, p<.001), surgical duration (124.77±26.63/ 156.74±37.01 min; p<.01) and intraoperative blood loss (310.47±130.73 ml vs. 429.77±148.50 ml; p<.05) were significantly less in the ESPB group. In the postoperative period, the control group's pain score was significantly higher (p<.001). The Modified Observer Alertness/Sedation Score (MOASS) score and satisfaction scores also showed significant differences between the case and control groups (p<.001). The mean time required to ambulate (sitting/walking) was statistically less in cases (15.81±6.15/20.72±4.02 h) when compared to controls (16.86±6.18/ 23.05±8.88 h; p<.001).

CONCLUSION

In patients undergoing PCSS, ESPB is a safe and effective technique with better outcomes than standard multimodal analgesia alone, in terms of reduced intraoperative opioid requirements and blood loss, better postoperative analgesia and early mobilization.

AO Spine upper cervical injury classification system: a description and reliability study

BACKGROUND CONTEXT

Prior upper cervical spine injury classification systems have focused on injuries to the craniocervical junction (CCJ), atlas, and dens independently. However, no previous system has classified upper cervical spine injuries using a comprehensive system incorporating all injuries from the occiput to the C2-3 joint.

PURPOSE

To (1) determine the accuracy of experts at correctly classifying upper cervical spine injuries based on the recently proposed AO Spine Upper Cervical Injury Classification System (2) to determine their interobserver reliability and (3) identify the intraobserver reproducibility of the experts.

STUDY DESIGN/SETTING

International Multi-Center Survey.

PATIENT SAMPLE

A survey of international spine surgeons on 29 unique upper cervical spine injuries.

OUTCOME MEASURES

Classification accuracy, interobserver reliability, intraobserver reproducibility.

METHODS

Thirteen international AO Spine Knowledge Forum Trauma members participated in two live webinar-based classifications of 29 upper cervical spine injuries presented in random order, four weeks apart. Percent agreement with the gold-standard and kappa coefficients (ƙ) were calculated to determine the interobserver reliability and intraobserver reproducibility.

RESULTS

Raters demonstrated 80.8% and 82.7% accuracy with identification of the injury classification (combined location and type) on the first and second assessment, respectively. Injury classification intraobserver reproducibility was excellent (mean, [range] ƙ=0.82 [0.58-1.00]). Excellent interobserver reliability was found for injury location (ƙ = 0.922 and ƙ=0.912) on both assessments, while injury type was substantial (ƙ=0.689 and 0.699) on both assessments. This correlated to a substantial overall interobserver reliability (ƙ=0.729 and 0.732).

CONCLUSIONS

Early phase validation demonstrated classification of upper cervical spine injuries using the AO Spine Upper Cervical Injury Classification System to be accurate, reliable, and reproducible. Greater than 80% accuracy was detected for injury classification. The intraobserver reproducibility was excellent, while the interobserver reliability was substantial.

Lumbo-sacral Junction Instability by Traumatic Sacral Fractures: Isler's Classification Revisited - A Narrative Review

STUDY DESIGN

Narrative review.

OBJECTIVES

Multiple classifications have been proposed for sacral fractures since the last century. While initial classifications focussed on vertical and transverse fractures, the recent fracture classifications encompass all injury patterns. In 1990, Isler classified unilateral vertical sacral fractures based on its potential influence on lumbo-sacral joint (LSJ) stability.

METHODS

We re-visited the original description of Isler's classification of sacral fractures and subsequent studies that have cited it. We will further describe basic LSJ anatomy, evolution of sacral classification systems and the use of Isler's classification system as it relates to LSJ instability and chronic low back pain.

RESULTS

Isler described a subset of unilateral vertical sacral fractures where the fracture line exited medial or through the L5-S1 facet joint, based on radiographic review of 193 sacral fractures (incidence -3.5%). He stated that such a fracture should be recognised as it can impede hemi-pelvis reduction and can result in late LSJ instability. The article has been cited in 106 studies and only a few studies have described the incidence of this variant. Nevertheless, the injury is considered as an indication for surgical fixation.

CONCLUSION

A review of various classifications indicates that sacral fractures have three important bio-mechanical implications, namely, pelvic ring continuity (vertical fractures), spino-pelvic alignment (high transverse fractures) and lumbo-sacral joint integrity (Isler's fractures). Though there is a universal recognition of Isler's fractures and its impact on LSJ integrity, there is a lack of clinical and bio-mechanical evidence regarding the concept of instability caused by a unilateral Isler fracture.

Efficacy of Non-Fusion Surgeries in the Management of AO Type C Injuries of the Thoracic and Thoracolumbar Spine: A Retrospective Study

BACKGROUND

The initial descriptions of successful management of non-fusion surgeries in the management of unstable burst injuries of the thoracic and thoracolumbar spine (TTLS) were published by Osti in 1987 and Sanderson in 1999. These were further supported by prospective studies and meta-analyses establishing comparable results between fusion and non-fusion surgeries. However, there is a paucity of literature regarding the efficacy of non-fusion surgeries in the management of AO type C injuries.

OBJECTIVE, MATERIALS AND METHODS

The study aims to determine the efficacy of open posterior instrumented stabilization without fusion in AO type C injuries of the TTLS. Patients with AO type C injuries of the TTLS (T4-L2 levels) with normal neurology who underwent open, posterior, long segment instrumented stabilization without fusion between January 2015 and June 2018 were included. The regional kyphotic angle, local kyphotic angle, AP (anterior and posterior wall) ratio, and cumulative loss of disc space angle were assessed on radiographs. Functional outcome was assessed using Oswestry Disability Index (ODI) and the AO Spine patient-reported outcome spine trauma (PROST) instrument.

RESULTS AND CONCLUSION

The study included 35 patients with AO type C injury of the TTLS and a normal neurology who underwent open posterior instrumented stabilization and had a mean follow-up of 43.2 months (range 24-60 months). The mean preoperative regional kyphotic angle decreased from 19.8 ± 13.7° to 6.6 ± 11.3° after surgery but showed an increase to 9.21 ± 10.5° at final follow-up (P = 0.003). The cumulative loss of disc space angle was significant at final follow-up (2.4 ± 5° [P = 0.002]). Twenty-eight out of 35 patients had minimal while seven had moderate disability on the ODI score. The AO Spine PROST revealed that patients regained 95.7 ± 4.2% of their pre-injury functional status at final follow-up. Posterior instrumented stabilization without fusion in the management of AO type C injuries of the TTLS gives satisfactory results with acceptable functional and radiological outcomes.

Patterns of Traumatic Spinal Injuries in the Developing World: A Five-Year Longitudinal Review

Study Design

Retrospective review.

Purpose

A 5-year longitudinal study documenting and comparing patterns of traumatic spinal injuries (TSIs) observed in developing countries.

Overview of Literature

Current knowledge of the patterns and epidemiology of TSI are based on evidence from developed countries and there is a lack of data from developing countries to enable a comparison of information to formulate healthcare policies.

Methods

A review of case records of all patients treated at a tertiary level trauma center over a 5-year period (2015-2019) was performed. Epidemiological, clinical, and radiological data were analyzed.

Results

The incidence of spinal trauma was 6.2% (2,065/33,072) among all trauma patients. Among these 2,065 patients, the mean age was 43.4±16.3 years and 77.3% (n=1,596) were aged 21-60 years. The major cause of injury was falls (52.1%, n=1,069) and 49.8% were high-energy falls (>10 feet [=3.048 m]). In patients with TSI due to falls, injuries occurred at the workplace (n=376), home (n=309), trees (n=151), wells (n=77), and electric poles (n=57). Road traffic accidents contributed to 42% (n=862) of TSIs and predominantly affected motorcyclists (52%, n=467). Around half (53.5%, n=1,005) of all patients were in the lower socioeconomic strata. The most common injury level was thoracic region (37.2%, n=769). Spinal cord injury (SCI) occurred in 49% (n=1,011) of patients and 49.7% (n=1,028) had injuries associated with other organs.

Conclusions

Our study indicated different demographic patterns and epidemiological features of TSI compared with the Western literature, including a preponderance of young male patients, falls from heights, motorcycle accidents, and a larger percentage of SCI. The high number of falls at workplace indicates a lack of knowledge among the public and policy makers about safety measures.

Advanced disc degeneration, bi-planar instability and pathways of peri-discal gas suffusion contribute to pathogenesis of intradiscal vacuum phenomenon

PURPOSE

Intradiscal vacuum phenomenon (IDVP), despite being ubiquitous, is poorly understood. The dynamic passage of peri-discal gases into the degenerated disc is a commonly accepted theory. But the reasons behind its selective appearance in some discs are unevaluated.

METHODS

721 patients with chronic low back pain ± radiculopathy, were evaluated with AP and flexion-extension lateral radiographs and MRI. IDVP was classified based on its morphology and location. Radiographic parameters including sagittal translation, sagittal angulation, lateral listhesis, eccentric disc collapse, Pfirrmann's grade, disc height, Modic changes, anterior longitudinal ligament status, and primary spinal disease at the level of IDVP was analyzed.

RESULTS

IDVP was present in 342 patients, and they had a higher mean age (57.2 ± 12.5 years) than controls (p < 0.001). Eccentric disc space narrowing (26.5% vs 1.3%, p < 0.01), coronal listhesis (7.83% vs 1.1%, p < 0.001), sagittal angular motion difference (11.3 ± 4.6°, p < 0.001), higher mean disc degeneration (4.36 ± 0.69, p < 0.001), ALL disruption (30.3% vs 2.2%, p < 0.001) and Modic changes (88.6% vs 17.5%, p < 0.001) were significantly higher in IDVP discs (vs. non-IDVP). Binary logistic regression analysis indicated sagittal angular motion difference was the most predictive factor. IDVP was classified into three types-dense type (47.5%), linear (29.5%), dot type (23%). Dense type matched radiological correlations of IDVP while dot types behaved like non-IDVP discs.

CONCLUSION

Modic disc-endplate contacts, ALL disruption and coronal translation could be pathways for the passage of peri-discal gases into the degenerated disc. In the pathogenesis of IDVP, advanced disc degeneration, the presence of pathways of gas transfer and angular/coronal instability seem to play complementary roles.

Macrodystrophia Lipomatosa of Thoracic Spine Causing Progressive Neurodeficit: A Case Report and Review of Literature

CASE

We report the first case of a 21-year-old male patient with macrodystrophia lipomatosa (MDL), with local gigantism involving the thoracic spine and progressively worsening neurodeficit. Imaging studies revealed fatty infiltration and hypertrophied intercostal nerves, dextroscoliosis, osseous hypertrophy between C4 and T2, and severe canal stenosis at the T4 to T5 level secondary to lamino-facetal hypertrophy. He underwent debulking of the lesion and posterior instrumented decompression in a staged manner. His neurodeficit improved postoperatively and was ambulant without support at the end of the 2-year follow-up.

CONCLUSION

Surgery in patients with MDL is technically challenging and fraught with complications such as neurological deficit and significant blood loss.

The Impact of COVID-19 on Future Orthopaedic Practice

No single event hitherto has stumped the world more significantly than the present Corona pandemic. In a short span of a few months, the world economy, healthcare, livelihood, and human survival have been direly threatened by the rapid increase in the number of COVID-19 cases and fatalities. While dispensations across the world are finding ways to tackle the pestilence, the medical fraternity faces a unique conundrum. On the one side, the health care team is at the forefront fighting the disease and saving patients from the grip of death. On the other side, the healthcare industry is facing a crisis in terms of safety of healthcare personnel, difficulties in online tele-healthcare, economic sustainability, challenges in healthcare education and other problems in safe health care delivery. The authors provide a broad perspective at the current pandemic and its implications on orthopaedic practice in the near future.

Description and Reliability of the AOSpine Sacral Classification System

BACKGROUND

Several classification systems exist for sacral fractures; however, these systems are primarily descriptive, are not uniformly used, have not been validated, and have not been associated with a treatment algorithm or prognosis. The goal of the present study was to demonstrate the reliability of the AOSpine Sacral Classification System among a group of international spine and trauma surgeons.

METHODS

A total of 38 sacral fractures were reviewed independently by 18 surgeons selected from an expert panel of AOSpine and AOTrauma members. Each case was graded by each surgeon on 2 separate occasions, 4 weeks apart. Intrarater reproducibility and interrater agreement were analyzed with use of the kappa statistic (κ) for fracture severity (i.e., A, B, and C) and fracture subtype (e.g., A1, A2, and A3).

RESULTS

Seventeen reviewers were included in the final analysis, and a total of 1,292 assessments were performed (646 assessments performed twice). Overall intrarater reproducibility was excellent (κ = 0.83) for fracture severity and substantial (κ = 0.71) for all fracture subtypes. When comparing fracture severity, overall interrater agreement was substantial (κ = 0.75), with the highest agreement for type-A fractures (κ = 0.95) and the lowest for type-C fractures (κ = 0.70). Overall interrater agreement was moderate (κ = 0.58) when comparing fracture subtype, with the highest agreement seen for A2 subtypes (κ = 0.81) and the lowest for A1 subtypes (κ = 0.20).

CONCLUSIONS

To our knowledge, the present study is the first to describe the reliability of the AOSpine Sacral Classification System among a worldwide group of expert spine and trauma surgeons, with substantial to excellent intrarater reproducibility and moderate to substantial interrater agreement for the majority of fracture subtypes. These results suggest that this classification system can be reliably applied to sacral injuries, providing an important step toward standardization of treatment.

Predictors of Successful Outcomes of Selective Nerve Root Blocks for Acute Lumbar Disc Herniation

STUDY DESIGN

Prospective, observational cohort study.

OBJECTIVE

Selective nerve root block (SNRB) is an effective, standard interventional procedure for failed medical management in lumbar disc herniation (LDH). However, the factors that would predict successful outcomes in patients undergoing SNRB have not been clearly studied.

METHODS

Patients with failed conservative treatment for acute LDH, treated with SNRB were periodically followed till 1 year. Patients who failed to have pain relief or had recurrent pain after SNRB, underwent surgery. The pattern of radiculogram during SNRB was classified into 4 types-"arm," "arrow," "linear," and "splash." Various clinical factors, radiological factors, and radiculograms were compared between patients who had consistent pain relief (group A) and those patients who did not (group B).

RESULTS

A total of 91 patients underwent SNRB. Sixty-nine had good pain relief maintained till 1 year (75.8% success). Twenty-two patients underwent surgery after failed NRB at a mean of 6.3 weeks. Patients with sensory symptoms (P = .01), higher mean preinjection Oswestry Disability Index (ODI) score (P = .02), higher mean postinjection ODI score at 3 weeks (P = .004), nonmanual job (P = .01), lumbosacral transitional segment (P = .00 005), and splash pattern of radiculogram (P = .005) were predictive of failed NRB. Logistic regression analysis showed that lumbosacral transitional segment at the level of LDH is the most significant factor predicting poor outcome.

CONCLUSIONS

SNRB is an effective technique to provide consistent symptom relief at least till 1 year in patients with acute LDH. The study identified several factors that predicted poor outcomes of SNRB and such patients can be forewarned about need for later surgery.

INFIX/EXFIX: Innovation managing pelvic fractures in difficult scenarios

Pelvic fractures complicated by the presence of visceral injuries, open fractures and urethral or bladder injuries pose a significant challenge to treat. In these conditions internal fixation is usually contraindicated. External fixators, though a potential solution, have disadvantages like loss of reduction, pin tract infection and loosening. INFIX, a novel technique has been effective in managing anterior ring fractures and can be used as a substitute for internal fixation. We describe use of INFIX as EXFIX in three case scenarios where passing INFIX rod internally was precluded with favorable outcomes.

Diagnostic accuracy of whole spine magnetic resonance imaging in spinal tuberculosis validated through tissue studies

INTRODUCTION

Conventional diagnosis of spinal tuberculosis (TB) is based on a combination of clinical features, laboratory tests and imaging studies, since none of these individual diagnostic features are confirmatory. Despite the high sensitivity of MRI findings in evaluating spinal infections, its efficacy in diagnosing spinal TB is less emphasized and remains unvalidated through tissue studies.

METHODOLOGY

We reviewed consecutive patients evaluated for spondylodiscitis with documented clinical findings, MRI spine, and tissue analysis for histopathology, TB culture and genetic TB PCR. MRI features documented include location, contiguous/non-contiguous skip lesions, para/intraosseous abscess, subligamentous spread, vertebral collapse, abscess size/wall, disc involvement, end plate erosion and epidural abscess. Based on the results, patients were divided into two groups-CONFIRMED TB with positive culture/histopathology and NON-TB. The efficacy of MRI findings in accurately diagnosing spinal TB was compared between the two groups.

RESULTS

Among 150 patients, 79 patients were TB positive, and 71 were TB negative. Three MRI parameters showed significant differences (p < 0.001), namely subligamentous spread (67/79, 84.8%), vertebral collapse > 50% (55/79, 69.6%) and large abscess collection with thin abscess wall (72/79, 91.1%) being strongly predictive of TB. Combination of MRI findings had a higher predictive value. 97.5% of TB positive patients had at least one of these three MRI features, 89.8% patients had any two and 58.2% had all three.

CONCLUSION

Our study validated different MRI findings with tissue studies and showed spinal infections with large abscess with thin wall, subligamentous spread of abscess and vertebral collapse were highly suggestive of spinal tuberculosis. These slides can be retrieved under Electronic Supplementary Material.

A rare cause of late onset neurological deficit in post tuberculous kyphotic deformity-case report

Late onset neurological deficit is a rare complication of spinal tuberculosis. Reactivation of the disease and compression by internal gibbus are the common causes for late onset neurological deficit. We report a rare cause of late onset paraplegia in a patient with post tubercular kyphotic deformity. The late onset neurological deficit was due to the adjacent segment degeneration proximal to the kyphotic deformity. Posterior hypertrophied ligamentum flavum and anterior disc osteophyte complex caused the cord compression. The increased stress for prolonged period at the end of the deformity was the reason for the accelerated degeneration. Patient underwent posterior decompression, posterolateral and interbody fusion. Deformity correction was not done. To our best knowledge, this is only the second report of this unusual cause of late onset paraplegia.

Modified anterior-only reduction and fixation for traumatic cervical facet dislocation (AO type C injuries)

PURPOSE

Surgical reduction of uni and bi-facetal dislocations of the cervical spine (AO type C injuries) can be performed by posterior, anterior or combined approaches. Ease of access, low infection rates and less risks of neurological worsening has popularized anterior approach. However, the reduction of locked cervical facets can be intricate through anterior approach. We analyzed the safety, efficacy and outcomes at a minimum 1 year, of a novel anterior reduction technique for consecutively treated cervical facet dislocations.

MATERIALS AND METHODS

Patients with single level traumatic sub-axial cervical dislocation (n = 39) treated by this modified anterior technique were studied. The technique involved standard Smith-Robinson approach, discectomy beyond PLL, use of inter-laminar distracter to distract while Caspar pins were used as "joysticks" (either flexion-extension or lateral rotation moments are provided), to reduce the sub-luxed facets. Among 51 patients with cervical type C injury treated during the study period, 4 patients who had spontaneous reduction and 8 treated by planned global fusion were excluded.

RESULTS

39 patients of mean age 49.9 years were studied. The levels of injury included (C3-4 = 2, C4-5 = 5, C5-6 = 20, C6-7 = 12). 18 were bi-facetal and 21 were uni-facetal dislocation. One facet was fractured in 17 and both in 5 patients. 30% (n = 13) had a concomitant disc prolapse. The neurological status was as follows: 9 ASIA A, 9 ASIA C, 13 ASIA D and 8 ASIA E. All the patients were successfully reduced by this technique and fixed with anterior locking cervical locking plates. No supplemental posterior surgery was performed. 22 patients with incomplete deficit showed recovery. The mean follow-up was 14.3 months and there was no implant failure except one patient who had partial loss of the reduction.

CONCLUSION

Patients with traumatic sub-axial cervical dislocation (AO type C injuries) can be safely and effectively reduced by this technique. Other advantages include minimal blood loss, less risks of infection, shorted fusion zone, good fusion rate and neurological recovery.

A rare cause of recalcitrant coccydynia: benign dermoid cyst masquerading as coccygeal pain

PURPOSE

Coccydynia is a common entity in orthopedic practice, and various etiologies have been described for it. However, benign dermoid cyst causing coccydynia has not yet been reported.

METHODS

A 20-year-old male presented with typical symptoms of coccydynia recalcitrant to conservative treatment for 2 years. Since pain interfered with his daily activities, magnetic resonance imaging was performed which showed a circumscribed precoccygeal cystic lesion.

RESULTS

The patient underwent coccygectomy along with cyst excision. Histological examination revealed features of benign dermoid cyst. After surgery, the patient had excellent relief of his symptoms.

CONCLUSION

The case report identifies that the treating surgeon should be aware of benign dermoid cyst as one of the treatable but rare causes of intractable coccydynia, and MRI should be performed in patients with persistent coccygeal pain.

Posterior fixation including the fractured vertebra for severe unstable thoracolumbar fractures

BACKGROUND CONTEXT

Traditional short-segment fixation of unstable thoracolumbar injuries can be associated with progressive kyphosis and implant failure. Load sharing classification (LSC) recommends supplemental anterior reconstruction for fractures of score 7 or greater. Posterior fixation including the fractured vertebra (PFFV) has biomechanical advantages over conventional short-segment fixation. However, its efficacy in severe thoracolumbar injuries (LSC≥7) has not been studied.

PURPOSE

To study the clinical, functional, and radiologic results of PFFV for severe, unstable thoracolumbar injuries (LSC≥7) at a minimum of 2 years.

STUDY DESIGN

A retrospective review of case records.

PATIENT SAMPLE

Thirty-two patients with an unstable burst fracture of LSC≥7 treated with PFFV were included.

OUTCOME MEASURES

They included clinical outcomes: American Spinal Injury Association grade, visual analog scale (VAS), Oswestry Disability Index (ODI); and radiologic measures: segmental kyphosis angle, vertebral wedge angle, and percentage loss of anterior and posterior vertebral height.

METHODS

Thirty-two patients with LSC≥7 who had undergone PFFV, with a minimum follow-up of 2 years were studied for demographic, injury, and surgical details. Clinical and radiologic outcomes were measured before surgery and at 6, 12, and 24 months postoperatively. The presence of screw breakage, screw pullout, peri-implant loosening, and rod breakage were considered as criteria for implant failure.

RESULTS

None of the patients had postoperative implant failure at the final follow-up. The mean preoperative kyphosis angle was 22.9°±7.6°. This improved significantly to 9.2°±6.6° after surgery (p=.000). There was a loss of mean 2.4° (mean kyphosis angle of 11.6°±6.3°) at the final follow-up. The mean preoperative wedge angle was 23.0°±8.1°. This was corrected to 9.7°±6.2° (p=.000). There was a loss of kyphosis (mean 1.2°) in the follow-up period. The mean anterior and posterior vertebral height also showed significant improvements postoperatively, which were maintained at the final follow-up. The mean ODI and VAS scores at the end of 2 years were 17.5% and 1.6, respectively.

CONCLUSIONS

Reduction of unstable thoracolumbar injuries even with LSC≥7 can be achieved and maintained with the use of short-segment pedicle screw fixation including the fractured vertebra, avoiding the need for anterior reconstruction. In the current era of evolving concepts of fracture fixation, the relevance of LSC in the management of unstable burst fractures is questionable.

Patterns of lumbar disc degeneration are different in degenerative disc disease and disc prolapse magnetic resonance imaging analysis of 224 patients

BACKGROUND CONTEXT

Existing research on lumbar disc degeneration has remained inconclusive regarding its etiology, pathogenesis, symptomatology, prevention, and management. Degenerative disc disease (DDD) and disc prolapse (DP) are common diseases affecting the lumbar discs. Although they manifest clinically differently, existing studies on disc degeneration have included patients with both these features, leading to wide variations in observations. The possible relationship or disaffect between DDD and DP is not fully evaluated.

PURPOSE

To analyze the patterns of lumbar disc degeneration in patients with chronic back pain and DDD and those with acute DP.

STUDY DESIGN

Prospective, magnetic resonance imaging-based radiological study.

METHODS

Two groups of patients (aged 20-50 years) were prospectively studied. Group 1 included patients requiring a single level microdiscectomy for acute DP. Group 2 included patients with chronic low back pain and DDD. Discs were assessed by magnetic resonance imaging through Pfirmann grading, Schmorl nodes, Modic changes, and the total end-plate damage score for all the five lumbar discs.

RESULTS

Group 1 (DP) had 91 patients and group 2 (DDD) had 133 patients. DP and DDD patients differed significantly in the number, extent, and severity of degeneration. DDD patients had a significantly higher number of degenerated discs than DP patients (p<.000). The incidence of multilevel and pan-lumbar degeneration was also significantly higher in DDD group. The pattern of degeneration also differed in both the groups. DDD patients had predominant upper lumbar involvement, whereas DP patients had mainly lower lumbar degeneration. Modic changes were more common in DP patients, especially at the prolapsed level. Modic changes were present in 37% of prolapsed levels compared with 9.9% of normal discs (p<.00). The total end-plate damage score had a positive correlation with disc degeneration in both the groups. Further the mean total end-plate damage score at prolapsed level was also significantly higher.

CONCLUSION

The results suggest that patients with disc prolapse, and those with back pain with DDD are clinically and radiologically different groups of patients with varying patterns, severity, and extent of disc degeneration. This is the first study in literature to compare and identify significant differences in these two commonly encountered patient groups. In patients with single-level DP, the majority of the other discs are nondegenerate, the lower lumbar spine is predominantly involved and the end-plate damage is higher. Patients with back pain and DDD have larger number of degenerate discs, early multilevel degeneration, and predominant upper lumbar degeneration. The knowledge that these two groups of patients are different clinically and radiologically is critical for our improved understanding of the disease and for future studies on disc degeneration and disc prolapse.

Efficacy of diffusion tensor anisotropy indices and tractography in assessing the extent of severity of spinal cord injury: an in vitro analytical study in calf spinal cords

BACKGROUND CONTEXT

Signal intensity changes observed in magnetic resonance imaging (MRI) do not reveal the actual severity of axonal damage incurred in spinal cord injuries. Diffusion tensor imaging (DTI) is an imaging technique with a potential to track individual nerve fiber tracts.

PURPOSE

We explored the use of DTI in quantifying the extent of spinal cord injury and differentiated areas of injured spinal cord from regions with intact fiber tracts in a cadaveric animal model.

STUDY DESIGN

Radiological study on cadaveric calf spinal cord specimens.

METHODS

Diffusion tensor imaging was performed in six freshly acquired spinal cord specimens of Indian calves (Bos primigenius indicus). An axial single-shot echo planar parallel diffusion-weighted imaging sequence was done with a 1.5-tesla MRI. Through fixed seed points, tracking of white matter tracts was done. Diffusion tensor imaging anisotropy indices, fractional anisotropy (FA), apparent diffusion coefficient (ADC), relative anisotropy (RA), volume ratio (VR), and eigenvector (E1) values were acquired at each region of interest. Various injuries were then inflicted in the spinal cord, and DTI was repeated. The tractography images and DTI anisotropy indices were compared with those of the uninjured specimens.

RESULTS

The mean FA, ADC, VR, RA, and E1 values of normal spinal cord were 0.849±0.025, 0.52±0.073 μm(2)/ms, 0.250±0.04 μm(2)/ms, 0.889±0.027, and 1.178±0.22 μm(2)/ms, respectively. The average FA and RA of injured spinal cord regions were significantly decreased being 0.651±0.024 and 0.704±0.041, respectively, at the sites of mild compression. The mean VR values showed significant increase being 0.502±0.027 and 0.628±0.031 μm(2)/ms at the sites of mild and severe compression. Fractional anisotrophy, RA, and VR values showed a progressive alteration as the severity of compression increased. In contrast, the ADC and E1 values did not show significant changes at the sites of pathology. Tractography of injured spinal cord revealed that the white matter was disrupted at the injury site but preserved on the intact regions clearly differentiating regions of partial and complete transection and varying degrees of compression from normal spinal cord.

CONCLUSION

The study shows that DTI tractography is useful for structural imaging of the spinal cord. Fractional anisotrophy, RA, and VR parameters were found to be more sensitive than ADC and E1 values in assessing the severity of compression.

Diffusion tensor imaging of the spinal cord and its clinical applications

The identification of the extent of neural damage in patients with acute or chronic spinal cord injury is imperative for the accurate prediction of neurological recovery. The changes in signal intensity shown on routine MRI sequences are of limited value for predicting functional outcome. Diffusion tensor imaging (DTI) is a novel radiological imaging technique which has the potential to identify intact nerve fibre tracts, and has been used to image the brain for a variety of conditions. DTI imaging of the spinal cord is currently only a research tool, but preliminary studies have shown that it holds considerable promise in predicting the severity of spinal cord injury. This paper briefly reviews our current knowledge of this technique.

Sensitivity studies of pediatric material properties on juvenile lumbar spine responses using finite element analysis

The objective of the study was to determine the sensitivity of material properties of the juvenile spine to its external and internal responses using a finite element model under compression, and flexion-extension bending moments. The methodology included exercising the 8-year-old juvenile lumbar spine using parametric procedures. The model included the vertebral centrum, growth plates, laminae, pedicles, transverse processes and spinous processes; disc annulus and nucleus; and various ligaments. The sensitivity analysis was conducted by varying the modulus of elasticity for various components. The first simulation was done using mean material properties. Additional simulations were done for each component corresponding to low and high material property variations. External displacement/rotation and internal stress-strain responses were determined under compression and flexion-extension bending. Results indicated that, under compression, disc properties were more sensitive than bone properties, implying an elevated role of the disc under this mode. Under flexion-extension moments, ligament properties were more dominant than the other components, suggesting that various ligaments of the juvenile spine play a key role in modulating bending behaviors. Changes in the growth plate stress associated with ligament properties explained the importance of the growth plate in the pediatric spine with potential implications in progressive deformities.