United States

Background
Pedicle screw breach (PSB) is not uncommon following lumbar instrumentation, and in some instances, it may lead to vascular and/or neurologic complications. Previous literature suggested that screws crossing the vertebral midline on an anterior-posterior (AP) radiograph (or midsagittal on CT) are concerning for medial pedicle breach. 

Objective
Our primary aim was to map out the safe zones (SZ) of bilateral pedicle instrumentation and their relationship at each lumbar vertebral level. Our secondary aim was to evaluate the presence of SZs’ intersection at each lumbar level, denoting safe screw midline crossing not otherwise associated with medial pedicle breach.

Methodology
CT scans of 51 patients were randomly selected from “The Cancer Imaging Archive” (TCIA) online database for analysis. The Sectra 3D Spine software was used to create 3D renderings, place virtual screws, and make measurements. At each lumbar vertebra, the right and left pedicle corridors were mapped. At each pedicle, two screw positions were templated, the “medial limit screw” (MLS) and the “lateral limit screw” (LLS). Each limit screw was the most extreme position that the screw could exist in without causing a medial or lateral breach. The safe zone was defined as the zone between MLS and LLS (Figure 1). Measurements were taken for each level (between L1-L5) and side (Left, Right). 

Results
A total of 253 lumbar vertebrae from 51 patients (mean age 53.1, 56.9% male) were included. Two vertebrae from two patients were removed for poor image quality. Out of the 506 screw positions analyzed in our study, 97.4% had overlapping SZ and crossed the midplane without medial pedicle breach (Table 1). The significant factors (p &lt; 0.01) for safe midplane-crossing screws included: the screw length (L1-L5); the laterality of the screw entry point (L1-L4); and the pedicle diameter (L2 and L5). 

Conclusion
A midline crossing pedicle screw on a lumbar AP radiograph is not necessarily indicative of a medial pedicle screw breach. Anatomical (i.e. larger pedicle diameter) and technical (i.e. longer screws, and lateral entry points) factors allow for safety zone intersections and indicate safe midline crossing by pedicle screws.


2022 AMA Research Challenge

Evaluating the Safe Zone for Lumbar Pedicle Screws: Are Midline Crossing Screws Indicative of Pedicle Screw Breach?

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Ricardo Correa, MD, EdD
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Stuart M. Greenstein, MD
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Stephanie Strohbeen, MD
 
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Jessica Li, MD/PhD Candidate
![](https://assets.underline.io/uploads/markdown_image/1/image/9950ef2e0237f54cb3d8280334d42491.jpg)
Charles Lopresto, DO

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Welcome to the largest national, multi-specialty research event featuring research from 750 medical students, residents and fellows, and international medical graduates.


Background
Pedicle screw breach (PSB) is not uncommon following lumbar instrumentation, and in some instances, it may lead to vascular and/or neurologic complications. Previous literature suggested that screws crossing the vertebral midline on an anterior-posterior (AP) radiograph (or midsagittal on CT) are concerning for medial pedicle breach. 

Objective
Our primary aim was to map out the safe zones (SZ) of bilateral pedicle instrumentation and their relationship at each lumbar vertebral level. Our secondary aim was to evaluate the presence of SZs’ intersection at each lumbar level, denoting safe screw midline crossing not otherwise associated with medial pedicle breach.

Methodology
CT scans of 51 patients were randomly selected from “The Cancer Imaging Archive” (TCIA) online database for analysis. The Sectra 3D Spine software was used to create 3D renderings, place virtual screws, and make measurements. At each lumbar vertebra, the right and left pedicle corridors were mapped. At each pedicle, two screw positions were templated, the “medial limit screw” (MLS) and the “lateral limit screw” (LLS). Each limit screw was the most extreme position that the screw could exist in without causing a medial or lateral breach. The safe zone was defined as the zone between MLS and LLS (Figure 1). Measurements were taken for each level (between L1-L5) and side (Left, Right). 

Results
A total of 253 lumbar vertebrae from 51 patients (mean age 53.1, 56.9% male) were included. Two vertebrae from two patients were removed for poor image quality. Out of the 506 screw positions analyzed in our study, 97.4% had overlapping SZ and crossed the midplane without medial pedicle breach (Table 1). The significant factors (p < 0.01) for safe midplane-crossing screws included: the screw length (L1-L5); the laterality of the screw entry point (L1-L4); and the pedicle diameter (L2 and L5). 

Conclusion
A midline crossing pedicle screw on a lumbar AP radiograph is not necessarily indicative of a medial pedicle screw breach. Anatomical (i.e. larger pedicle diameter) and technical (i.e. longer screws, and lateral entry points) factors allow for safety zone intersections and indicate safe midline crossing by pedicle screws.

poster

Fibular Displacement Predicts Tibial Malrotation in Simulated Tibia-Fibula Fractures

Gray Scale and Power Doppler Ultrasound Findings Predictive of Cubital Tunnel Syndrome Severity

Background Context: In the United States, the prevalence of inflammatory bowel disease (IBD) has increased concurrently with an aging population with degenerative disc changes. In these patients, primary 1- to 2-lumbar fusion (1-2LF) is a common procedure to resolve serious complications of the spine. Studies comparing these patient demographics to hospital lengths of stay, post-operative complications, readmission rates, and costs of care is limited in the literature.

Purpose: The purpose of this study was to determine whether IBD in patients with degenerative disc changes undergoing primary 1-2LF is associated with higher rates of: 1) in-hospital length of stay; 2) medical complications; 3) readmissions; and 4) costs of care.

Study Design/Setting: Retrospective Cohort Study

Patient Sample: The PearlDiver database was queried from 2010 to 2022 to identify patients who underwent primary 1- to 2- level lumbar fusion operations using International Classification of Diseases, Ninth and Tenth Revision, Clinical Modification (ICD-9-CM, ICD-10-CM) coding. Current Procedural Terminology (CPT) codes were also utilized to identify the patient cohort isolated.

Methods: A retrospective study using the PearlDiver database from the years 2010 to 2020 was performed to isolate IBD patients with degenerative disc disease undergoing primary 1-2LF. The inclusion criteria consisted of patients with IBD who underwent 1-2LF, using a 90-day surveillance period, post-operatively. This 90-day surveillance period was used to measure length of hospital stay, rates of medical complications, rates of readmissions, and overall costs of care. The IBD cohort was matched against a case-matched cohort group. The study yielded 20,640 patients, overall, with 3,446 IBD patients and 17,194 non-IBD patients. Baseline demographics were compared. Chi-Square Analyses were performed to properly match the two cohorts. Welch’s t-tests were used to test for significance for the length of stay and reimbursement data between both groups. Logistic regression analyses were utilized to calculate the odds-ratios (OR) and 95% confidence intervals (95%CI) to further analyze the association between IBD on post-operative outcomes after 1-2LF. Bonferroni adjustments were made and yielded an alpha value less than 0.001 as statistically significant. Finally, a p-value less than 0.05 was considered statistically significant.

Results: Patients in the study group had significantly longer in-hospital lengths of stay (4- vs. 3-days, p < 0.001). Additionally, patients in the study group had significantly higher incidence and odds of developing post-operative medical complications within 90 days (42.3% vs. 25.7%; OR: 1.73, p < 0.0001). Also, study group patients had significantly higher readmission rates (11.32% vs. 9.44%; OR: 1.22, p = 0.0007). Finally, patients in the study group had significantly higher costs of care than their case-matched cohort ($60,412.83 vs. $59,331.94, p < 0.0001).

Conclusions: This study demonstrated that patients with IBD and degenerative disc disease are burdened with longer in-hospital lengths of stay, rates of post-operative medical complications, rates of readmission, and costs of care after undergoing primary 1-2LF. Spine surgeons and other orthopaedic professionals would benefit from providing adequate counseling to this patient demographic so patients are fully aware of the potential post-operative burdens they may accrue.

Keywords: Lumbar Fusion; Inflammatory Bowel Disease; Degenerative Disc Disease

How Does Inflammatory Bowel Disease Impact Outcomes and Costs of CareFollowing Primary 1- to 2- Level Lumbar Fusion for Degenerative Disc Disease?

How Has COVID-19 Affected Rates of Musculoskeletal Pain and Digital Media Use in Children?

Amnion epithelial and mesenchymal cells have been shown in vitro to contain a variety of regulatory mediators that result in the promotion of cellular proliferation, differentiation, epithelialization, and the inhibition of fibrosis, immune rejection, inflammation, and bacterial invasion. Amniotic membrane products are approved for use as human cells, tissues, and cellular and tissue-based products (HCT/Ps) under the 361 or 351 pathways of the Food and Drug Administration (FDA). Previously reported clinical applications of human amniotic membrane (hAM) include nerve repair, tendon injury, joint and cartilage damage, and wound management. Although there is some evidence regarding the use of amniotic allografts in animals, there is a paucity of literature regarding their use to treat pathology of the hand and wrist. Further investigation is necessary to determine their effectiveness and therapeutic value in the upper extremity.

Human Amniotic Allograft in Hand Surgery

Abstract Title: In vitro Murine Bioassay of IL-12-loaded PLGA Nanoparticles

Background: The cytokine Interleukin (IL)-12 has been shown to have significant anti-tumor effects through its impact on the differentiation of T helper cells and M1 activation of macrophages. While intravenous (i.v.) IL-12 has shown anti-tumor effects in murine models, in human clinical trials, research has been halted due to limited efficacy and serious side effects. These side effects are believed to be due to peripheral immune exhaustion associated i.v. IL-12 delivery. Nanoparticle encapsulation of IL-12 (nIL- 12) with Poly(D,L-lactide-co-glycolide) acid (PLGA) shows the potential to retain anti-tumor effects while mitigating dose-limiting toxicity. After injection, these PLGA nanospheres distribute systemically, deposit into tissues (limiting immune stimulation in the peripheral blood), and then slowly release encapsulated IL-12. Development of an in vitro bioassay is particularly important to ensure that the bioactivity of IL-12 is not altered following nanoparticle synthesis and encapsulation.

Methods: Following an in vitro study of nIL-12 elution, nIL-12 was used to stimulate male C57BL/6 murine splenocytes. Cultured splenocytes were exposed to five 10-fold serial dilutions of nIL-12, concentration-matched stock (unencapsulated) IL-12 (sIL-12), or unloaded nanoparticles. Production of IFN-γ was evaluated via ELISA; an ED-50 curve (IL-12 concentration vs IFN-γ production) was generated.

Results: nIL-12 and sIL-12 were diluted to an average of 18257.93, 1825.79, 182.57, 18.25, and 1.82 pg of IL-12. nIL-12 produced an average of 32652.26, 98022.06, 52440.92, 17883.45, and 991.26 pg of IFN- γ, respectively, yielding an ED50 of 40.4 ± 16.45 pg/mL. sIL-12 produced an average of 59404.67, 101668.97, 67137.01, 23587.61, and 7255.68 pg of IFN-γ, respectively, yielding an ED50 of 119.0±35.04 pg/mL. There was no statistically significant difference in ED50 between nIL-12 and sIL-12 (p = 0.1477). Thus, PLGA encapsulation was not found to alter cytokine bioactivity.

Conclusion: Successful validation of IL-12 bioactivity post-encapsulation is a critical quality control measure that shows IL-12 can be loaded into PLGA nanoparticles. These results support an in vitro dose- dependent IFN-γ response to nIL-12. Further experiments will evaluate in vivo immunological response in a murine model of metastatic osteosarcoma.

In vitro Murine Bioassay of IL-12-loaded PLGA Nanoparticles

Intraoperative Full-Length Radiographs after Long Bone Nailing Increase Anesthesia Time and Costs, But Do Not Lead to Revision
Patrick Ryan, M21, Michael Beltran, MD2, Nihar Shah, MD2
1: University of Cincinnati College of Medicine, Cincinnati, Ohio
2: Department of Orthopaedic Surgery, University of Cincinnati College of Medicine

Background:
The treatment of long bone fractures places a large socioeconomic burden on the workforce of the USA. Plate fixation, external fixation, and intramedullary nailing are the most common treatment options for these fractures. Surgeons performing intramedullary nailing of lone bone fractures often employ intraoperative full-length radiographs prior to reversal of general anesthesia—even after utilizing intraoperative fluoroscopy, but it is unknown if this alters patient care. The purpose of this study is to determine if intraoperative full-length ‘check radiographs’ alter patient care. We theorized that these radiographs rarely alter care and are associated with increased costs and anesthesia time.
Methods:
Medical records of patients undergoing fluoroscopy-guided tibial and femoral nailing operations at the University of Cincinnati Medical Center between June 2018 and June 2021 were reviewed. Data about the patient demographics, fracture characteristics, operative details, and reintervention status were collected from 734 procedures. Standard statistical techniques were utilized to compare reintervention rates.
Results:
Of the 734 procedures reviewed, five were excluded because the status of intraoperative check radiograph imaging was not included in the chart. The remaining 729 procedures included 673 cases where check radiographs were taken (with a median of four images captured per procedure) and 56 cases where surgeons used only intraoperative fluoroscopic images to assess for proper nail placement. Only two of the 673 check radiographs (0.29% [0%, 0.7%]) led to intraoperative revision nailing during the same anesthetic event, and 36 check radiographs (5.3% [3.6%, 7.0%]) resulted in reintervention surgeries at later dates. In the cohort not receiving check radiographs, five patients (8.9% [1.5%, 16.4%]) required reintervention surgery at a later date. No significant difference in overall reintervention rate was found between procedures which did not use check radiographs and those procedures which did (odds ratio = 1.64 [0.62, 4.34]; p=0.317).
Conclusion:
Intraoperative full-length radiographs after tibial and femoral nailing rarely lead to revision surgery during the same anesthetic event. We found no difference in reintervention for tibial and femoral nailing procedures with and without check radiographs. The increased anesthesia time, costs, and surgical delays associated with obtaining these radiographs do not appear to be justified.


Intraoperative Full-Length Radiographs after Long Bone Nailing Increase Anesthesia Time and Costs, But Do Not Lead to Revision

Abstract Title: Minimally Invasive Approach to Bicondylar Tibial Plateau Fractures: The Hopscotch Incision
Background
Bicondylar tibial plateau fractures represent a complex subset of fractures that are often difficult to treat and associated with high rates of infection. Open reduction and internal fixation (ORIF) was historically performed through a single midline incision; however, due to unacceptable rates of complications, technique has shifted to the use of a single anterolateral or dual anterolateral and medial incisions. With the goal of further improving rates of complication we present a minimally invasive alternative: the “hopscotch” approach.
Methods
Two adult males who sustained bicondylar tibial plateau fractures were treated with ORIF using the hopscotch approach. This approach segments either or both the anterolateral and medial incisions into proximal and distal components. The anterolateral incision is made 2 to 3 cm proximal to the joint line and continued distally over the Gerdy’s tubercle while remaining 1 cm lateral to the tibial crest. The medial incision is made 1 to 2 cm proximal to the joint in line and extended over the pes anserinus insertion and posteromedial border of the tibia. However, instead of completing the full length of the incisions, the proximal portions are extended only as far as needed for visualization and reduction of the fracture. Chosen implants are then inserted proximally and slid distally under the skin. Secondary incisions are then made distally for exposure and fixation of the chosen implant, leaving intervening bridges of skin and subcutaneous tissue intact.
Results
No complications were noted at two week and three month follow-up visits for either patient. Incisions were well healed with no evidence of infection or radiographic abnormality.
Conclusion
This study showcases two examples of bicondylar tibial plateau fractures treated operatively via the hopscotch approach. In theory, minimizing total incisional length, soft tissue manipulation, and disruption of vascular supply should decrease rates of infection and skin necrosis; however, prospective studies are required to fully evaluate the benefits of this approach.

Minimally Invasive Approach to Bicondylar Tibial Plateau Fractures: The Hopscotch Incision

Abstract Title: Mortality and Complications in Patients with Chronic Kidney Disease (CKD) Following Lower Extremity Trauma
Authors: Margaret Fisher MS, Jason McCartney BS, Kristin A Toy MD, MS, Beau White MD, Di Hu MS, Feng-Chang Lin PhD, Judith Siegel MD, Robert Ostrum MD, Andrew Chen MD, MPH

Background: Moderate-to-severe chronic kidney disease (CKD) and end-stage renal disease (ESRD) are independent risk factors for sustaining a fragility fracture due to abnormalities within bone structure and metabolism. This study aims to assess complications in these patients following surgical management of all lower extremity fractures, as previous studies have largely focused on only hip fractures. 

Methods: This was a single-center, retrospective study of patients with CKD/ESRD who underwent operative management of lower extremity fractures between 2008-2019. Patients were stratified into three cohorts by CKD stages using estimated glomerulus filtration rate (GFR) at the time of surgery (mild (stages 1-2); GFR ≥ 60, moderate-severe (stages 3-4); GFR 15-59, ESRD (stage 5); GFR <15 or dialysis). Charlson Comorbidity Index (CCI) and fracture characteristics were collected. Outcomes of interest including minor complications (DVT, cellulitis, delayed wound healing), major complications (hardware failure, nonunion/malunion, deep infection, peri-implant fracture), and 2-year mortality were compared between cohorts using Chi-squared, ANOVA, and Fisher’s exact tests. A multivariable logistic regression assessed independent associations of moderate-severe CKD/ESRD on mortality and complications. 

Results: 356 patients with fractures of the pelvis/acetabulum (4.6%), hip (28.0%), femoral/tibial shafts (18.0%), peri-articular (22.4%), ankle (25.1%) and patella (1.9%) were included. Demographics were similar between cohorts except for age, race, and CCI. Mortality rates were significantly different between ESRD and mild CKD groups at 90 days (15.7% vs. 5.5%; p=.033), 1 year (27.1% vs. 10.5%; p=.005), and 2 years (47.1% vs. 17.0%; p<.0001). Overall complications and major complications were higher with increasing CKD severity (14.8%, 31.0%, 40.7%, p<0.0001 and 13.3%, 22.5%, 33.9%, p<0.001). After adjusting for CCI, multivariate analysis demonstrated a positive association between ESRD and mortality at 90 days (OR 4.5, 95%CI 1.3, 15.1), 1 year (OR 2.7, 95%CI 1.1, 6.5) and 2 years (OR 5.2, 95%CI 2.3, 11.6). Complications were associated with moderate/severe CKD (OR 2.2, 95% CI 1.1, 4.3, p=.0004) and ESRD (OR 4.1, 95%CI 1.8, 9.4, p<.0001). 

Conclusion: This study demonstrates high mortality and complication rates for patients with moderate-to-severe CKD who undergo operative fixation of a lower extremity fracture. These findings can be used to counsel patients regarding realistic expectations of complications.

Mortality and Complications in Patients with Chronic Kidney Disease Following Lower Extremity Trauma

Background
Distal femur fractures (DFFs) represent approximately 1% of all fractures and 3-6% of femur fractures. Management of DFFs can be challenging, particularly in the aged female population due to predisposition to osteoporosis and osteopenia and higher risk of other comorbidities. This retrospective study aims to analyze the surgical outcomes of aged female patients with non-periprosthetic DFFs treated with a locking plate (LP).

Methods
Fifty-five female patients (mean age of 71 years) with non-periprosthetic DFF underwent open reduction internal fixation using a LP from 2005 to 2019. The mean follow-up time was 67 weeks from the date of injury. Criteria used for diagnosis of nonunion included one or more of the following: (1) three consecutive months without progression of healing on postoperative radiographs, (2) a total of nine months without complete healing, or (3) physician-diagnosed nonunion using clinical judgement. Outcome data was analyzed and compared amongst patients with and without obesity or diabetes. Statistical analysis was performed with a standard statistically significant p-value of < 0.05.

Results
Thirty-two patients (58%) with DFF achieved union after initial treatment while 23 patients (42%) resulted with nonunion. 14 patients (61%) underwent revision with nine of these patients (64%) achieving union while five patients (36%) had persistent nonunion. Average healing time from initial treatment was 29 weeks, while average time from definitive treatment to union was 22 weeks. Obese (BMI >30) and non-obese patients had a nonunion rate of 65% and 28%, respectively (p = 0.008). Patients with diabetes had a nonunion rate of 65%, while patients without diabetes had a nonunion rate of 28% (p = 0.008).

Conclusion
Union can be successfully achieved in aged female patients with distal femur fractures treated with locking plate. However, the risks for nonunion and revision remain high and patients with obesity and diabetes appear to be at an increased risk. Further research should be conducted with a prospective study or multivariate analysis and increased number of patients to reaffirm this data.

Evaluating the Safe Zone for Lumbar Pedicle Screws: Are Midline Crossing Screws Indicative of Pedicle Screw Breach?

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Fibular Displacement Predicts Tibial Malrotation in Simulated Tibia-Fibula Fractures

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