Risk of Infection Following Gunshot Wound Fractures to the Foot and Ankle: A Multicenter Retrospective Study.

The purpose of this multicenter retrospective chart review was to describe demographics, fracture and wound characteristics, and treatments for foot and/or ankle fractures caused by gunshot wounds (GSWs) and identify factors that increase risk of infection in adults treated at 5 urban level 1 trauma centers in South and Midwest regions of the United States. A total of 244 patients sustained GSW-related fractures of the foot/ankle during 2007-2017, of whom 179 had ≥30 days of follow-up data after the initial injury. Most patients were male (95.1%; 232/244) with an average age of 31.2 years. On average, patients sustained 1.3 GSWs (range 1-5) to the foot/ankle. Most GSWs were categorized as low energy (85.1%; 171/201) and the majority (58.2%; 142/244) had retained bullet fragments. Antibiotics were administered at initial presentation to 78.7% (192/244) of patients and 41.8% (102/244) were managed operatively at the time of initial injury. Nerve injury, vascular injury, and infection were documented in, respectively, 8.6% (21/243), 6.6% (16/243), and 17.2% (42/244) of all cases. Multivariable analysis revealed that high-energy injuries and retained bullet fragments increased the risk of infection by 3-fold (odds ratio 3.09, 95% confidence interval 1.16-8.27, p = .025) and 3.5-fold (OR 3.48, 95% CI1.40-8.67; p = .008), respectively. Side of injury, primary injury region, and vascular injury were not significant predictors of infection risk. Further research should examine whether retained bullet fragments are directly associated with infection risk and support the development of guidelines regarding the management of patients with GSW-related fractures to the ankle/foot.

Poor Outcomes After Anterior Impaction Pilon Fractures.

INTRODUCTION: Pilon fractures occur through high-energy axial-loading trauma and are frequently associated with complications. The goal of this study was to assess whether anterior impaction (AI) tibial pilon fractures are associated with increased rates of posttraumatic osteoarthritis (PTOA), secondary surgeries, and lower patient-reported outcomes compared with patients with non-AI pilon fractures. METHODS: In this retrospective cohort study, 52 pilon fractures in 50 patients were included. The average follow-up was 25 months (range, 12 to 62 in non-AI and 12 to 66 in AI). The Kellgren and Lawrence (KL) score for PTOA, tibiotalar ratio for anterior-posterior talar subluxation, coronal tibiotalar angle, Patient-Reported Outcomes Measurement Information System score, and rates of secondary surgeries and infection were assessed. RESULTS: The AI group showed radiographic evidence of more advanced PTOA at the final follow-up (KL score 3.1 vs. 2.5, P = 0.021) and a higher rate of implant removal for pain (39% vs. 13%, P = 0.030). AI also had greater anterior talar subluxation on preoperative (P < 0.001) and final follow-up radiographs (P = 0.026). A higher KL score was associated with greater anterior talar displacement on preoperative (r = -0.421, P = 0.003) and final follow-up radiographs (r = -0.359, P < 0.009). No differences were seen in 1-year Patient-Reported Outcomes Measurement Information System scores. DISCUSSION: AI pilon fractures are associated with recurrent anterior talar subluxation, more severe PTOA, and a higher rate of implant removal for pain compared with non-AI fractures.

Patient Age Is Inversely Associated with Injury Counts Caused by Motor Vehicle Crashes.

Associations between age and fracture incidence, total number of fractures, and total number of injuries per occupant occurring in motor vehicle crashes were evaluated. An observational study of the Crash Injury Research and Engineering Network was conducted. Multivariable logistic regression and negative binomial models were used to relate age (2064, 65+ years) to fracture incidence, total number of fractures per occupant, and total number of injuries, adjusting for sex and change in vehicle velocity (deltav). Over 90% of occupants had at least one fracture for a total of 5,846 fracture injuries. The older age group experienced a 15% increase in the incidence of total injuries sustained compared to the younger group (Incident Rate Ratio = 1.15, 95% Confidence Interval = 1.081.23, p 0.0001). Older patients should be considered for polytrauma evaluation even with a lower energy motor vehicle crash. (Journal of Surgical Orthopaedic Advances 29(1):3639, 2020).

Hip dislocations and concurrent injuries in motor vehicle collisions.

INTRODUCTION: Motor Vehicle Collisions (MVC) can cause high energy hip dislocations associated with serious injury profiles impacting triage. Changes in safety and regulation of restraint devices have likely lowered serious injuries from what was previously reported in the 1990s. This study aims to describe modern-day injury profile of patients with traumatic hip dislocations, with special attention to aortic injury. METHODS: Retrospective review of a prospectively maintained trauma database at an urban level 1 trauma center was conducted. Patients with hip dislocation following MVC between January 2005 and December 2015 were grouped based on seatbelt use and airbag deployment. Patients with unknown restraint use were excluded. Multiple logistic regression was used to identify risk of injury profile between groups. RESULTS: Of 204 patients with hip dislocation after MVC, nearly 57% were unrestrained. Seatbelt alone was used in 36 (17.7%), airbag deployed in 14 (6.9%), and 38 (18.6%) with both. Gender and number of injuries were similar between groups. The most common concomitant injury was acetabular fracture (53.92%) and the abdominopelvic region was the most injured. Use of a seatbelt with airbag deployment was protective of concomitant pelvic ring injury (OR = 0.22). Airbag deployment was significantly protective of lumbar fracture (OR = 0.15) while increasing the likelihood of radial and ulnar fracture or dislocation (OR = 3.27), acetabular fracture (OR = 5.19), and abdominopelvic injury (OR = 5.07). The no restraint group had one patient (0.80%) with an intimal tear of the thoracic aorta identified on CT chest that was successfully medically managed. DISCUSSION AND CONCLUSION: Hip dislocations are high energy injuries with severe associated injuries despite upgrades in restraint devices. These patients require careful examination and heightened awareness when evaluating for concomitant injuries.

A Retrospective Analysis of Complications Associated With Bone Morphogenetic Protein 2 in Anterior Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective review. OBJECTIVE: The aim of our study was to quantify the frequency of complications associated with recombinant human bone morphogenetic protein 2 (rhBMP-2) use in anterior lumbar interbody fusion (ALIF). METHODS: The orthopedic subset of the Medicare database (PearlDiver) was queried for this retrospective cohort study using International Statistical Classification of Diseases 9 (ICD-9) and Current Procedure Terminology (CPT) codes for ALIF procedures with and without rhBMP-2 between 2005 and 2010. Frequencies of complications and reoperations were then identified within 1 year from the index procedure. Complications included reoperations, pulmonary embolus, deep vein thrombosis, myocardial infarction, nerve-related complications, incision and drainage procedures, wound, sepsis, pneumonia, urinary tract infections, respiratory, heterotopic ossification, retrograde ejaculation, radiculopathy, and other medical complications. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the statistical significance. RESULTS: We identified a total of 41 865 patients who had an ALIF procedure. A total of 14 384 patients received rhBMP-2 while 27 481 did not. Overall, 6016 (41.8%) complications within 1 year from surgery were noted within the group who received rhBMP-2 and 12 950 (47.1%) complications within 1 year from surgery were recorded in those who did not receive rhBMP-2 (OR = 0.81, CI = 0.77-0.84). Overall, exposure to rhBMP-2 was associated with significantly decreased odds of complications with exception to reoperation rates (0.9% rhBMP-2 vs 1.0% no rhBMP-2; OR = 0.88, CI = 0.71-1.09) and radiculopathy (4.4% rhBMP-2 vs 4.3% no rhBMP-2; OR = 1.02, CI = 0.93-1.13). CONCLUSIONS: The use of rhBMP-2 in patients undergoing ALIF procedure was associated with a significantly decreased rate of complications. Further studies are needed to elucidate a true incidence of complication.

Return of motor evoked potentials after knee flexion in the setting of high-grade spondylolisthesis.

PURPOSE: To present a case of loss of motor-evoked potentials (MEPs) to the left foot in the supine position after a partial reduction and instrumented fusion from L4 to pelvis which was managed successfully without revision or removal of implants. METHODS: We report a patient with high-grade spondylolisthesis who demonstrated loss of motor-evoked potentials after posterior spinal fusion and transfer to supine position. The patient's knees were flexed to 90° and signals were immediately restored. Systemic steroids were administered and circumferential fusion was delayed 21 days. Anterior-interbody cage was placed without complication. RESULTS: She was discharged on post-operative day 2. At 7 months, she is pain free and doing well with plans to return to gymnastics completely. CONCLUSIONS: Knee flexion can be instituted when encountering a neuromonitoring signal change following posterior spinal fusion for spondylolisthesis as a means to alleviate acute nerve stretch injury and may in some cases prevent the need to lessen the correction. LEVEL OF EVIDENCE: IV.

The biomechanical effect of increased valgus on total knee arthroplasty: a cadaveric study.

The effects of valgus load on cadaveric knees following total knee arthroplasty (TKA) were investigated using a custom testing system. TKAs were performed on 8 cadaveric knees and tested at 0°, 30°, and 60° knee flexion in both neutral and 5° valgus. Fuji pressure sensitive film was used to quantify contact areas and pressures and MCL strain was determined using a Microscribe digitizing system. Lateral tibiofemoral pressures increased (P < 0.05) at all knee flexion angles with valgus loading. Patellofemoral contact characteristics did not change significantly (P > 0.05). Significant increases in strain were observed along the anterior and posterior border of the MCL at all knee flexion angles. These findings suggest that valgus loading increases TKA joint contact pressures and MCL strain with increasing knee flexion which may increase implant instability.

A new murine model of stress-induced complex atherosclerotic lesions.

The primary purpose of this investigation was to determine whether ApoE(-/-) mice, when subjected to chronic stress, exhibit lesions characteristic of human vulnerable plaque and, if so, to determine the time course of such changes. We found that the lesions were remarkably similar to human vulnerable plaque, and that the time course of lesion progression raised interesting insights into the process of plaque development. Lard-fed mixed-background ApoE(-/-) mice exposed to chronic stress develop lesions with large necrotic core, thin fibrous cap and a high degree of inflammation. Neovascularization and intraplaque hemorrhage are observed in over 80% of stressed animals at 20 weeks of age. Previously described models report a prevalence of only 13% for neovascularization observed at a much later time point, between 36 and 60 weeks of age. Thus, our new stress-induced model of advanced atherosclerotic plaque provides an improvement over what is currently available. This model offers a tool to further investigate progression of plaque phenotype to a more vulnerable phenotype in humans. Our findings also suggest a possible use of this stress-induced model to determine whether therapeutic interventions have effects not only on plaque burden, but also, and importantly, on plaque vulnerability.

Biomechanical effect of latissimus dorsi tendon transfer for irreparable massive cuff tear.

BACKGROUND: The purpose of this study was to determine the biomechanical effects of latissimus dorsi transfer in a cadaveric model of massive posterosuperior rotator cuff tear. METHODS: Eight cadaveric shoulders were tested at 0°, 30°, and 60° of abduction in the scapular plane with anatomically based muscle loading. Humeral rotational range of motion and the amount of humeral rotation due to muscle loading were measured. Glenohumeral kinematics and contact characteristics were measured throughout the range of motion. After testing in the intact condition, the supraspinatus and infraspinatus were resected. The cuff tear was then repaired by latissimus dorsi transfer. Two muscle loading conditions were applied after latissimus transfer to simulate increased tension that may occur due to limited muscle excursion. A repeated-measures analysis of variance was used for statistical analysis. RESULTS: The amount of internal rotation due to muscle loading and maximum internal rotation increased with massive cuff tear and was restored with latissimus transfer (P < .05). At maximum internal rotation, the humeral head apex shifted anteriorly, superiorly, and laterally at 0° of abduction after massive cuff tear (P < .05); this abnormal shift was corrected with latissimus transfer (P < .05). However, at 30° and 60° of abduction, latissimus transfer significantly altered kinematics (P < .05) and latissimus transfer with increased muscle loading increased contact pressure, especially at 60° of abduction. CONCLUSION: Latissimus dorsi transfer is beneficial in restoring humeral internal/external rotational range of motion, the internal/external rotational balance of the humerus, and glenohumeral kinematics at 0° of abduction. However, latissimus dorsi transfer with simulated limited excursion may lead to an overcompensation that can further deteriorate normal biomechanics, especially at higher abduction angles.

Effects of aging on time course of neovascularization-related gene expression following acute hindlimb ischemia in mice.

BACKGROUND: Molecular analysis of neovascularization related genes by time course in response to ischemia has not been described in the context of aging. We aimed to provide a progressively deeper understanding of how aging compromises neovascularization. METHODS: Young (3-month) and old (18-month) C57Bl mice were subjected to left hindlimb ischemia. Necrosis score was evaluated in calf muscles. Calf muscles, peripheral blood, bone marrow were harvested at different time points. The expressions of matrix metalloproteiniase-9 (MMP9), endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF), stromal derived growth factor-1 (SDF1), hypoxia inducible factor-1α (HIF1α), VEGF receptor-1 (Flt1), VEGF receptor-2 (Flk1), angiopoietin-1 (Ang1), CD133, CD26 were detected by RT-PCR or Western blotting. White blood cells were counted in the peripheral blood. Gene expression data were compared by two-way analysis of variance. RESULTS: MMP9, HIF-1α and SDF-1 were more upregulated during acute ischemia in old vs. young mice, reflecting increased ischemia in aging mice. However VEGF and eNOS exhibited lower expression in old vs. young mice, despite greater ischemia intensity. Ang1 and Flk1 showed similar expression in old vs. young mice. MMP9 peaked earlier in peripheral blood in young vs. old mice. Concurrent decreasing CD26 and increasing CD133 expression in aging bone marrow suggest aging impairs progenitor cell mobilization, CONCLUSIONS: Our results indicate that a complex array of defects occur with aging that interfere with optimal neovascularization. These include potential impaired mobilization of progenitor cells to ischemic tissue, decreased levels of eNOS and VEGF and delayed responses to ischemia.

Metallothionein enhances angiogenesis and arteriogenesis by modulating smooth muscle cell and macrophage function.

OBJECTIVE: In a previous study we identified metallothionein (MT) as a candidate gene potentially influencing collaterogenesis. In this investigation, we determined the effect of MT on collaterogenesis and examined the mechanisms contributing to the effects we found. METHODS AND RESULTS: Collateral blood flow recovery was assessed using laser Doppler perfusion imaging, and angiogenesis was measured using a Matrigel plug assay. Smooth muscle cells were isolated from MT knockout (KO) mice for functional assays. Gene expression of matrix metalloproteinase-9, platelet-derived growth factor, vascular endothelial growth factor, and Fat cadherin in smooth muscle cells was measured by real-time polymerase chain reaction, and protein levels of vascular endothelial growth factor and matrix metalloproteinase-9 were determined using enzyme-linked immunosorbent assay and Western blot. CD11b(+) macrophages were tested for invasiveness using a real-time impedance assay. Both flow recovery and angiogenesis were impaired in MT KO mice. Proliferation, migration, and invasion were decreased in MT KO smooth muscle cells, and matrix metalloproteinase-9, platelet-derived growth factor, and vascular endothelial growth factor expression were also decreased, whereas FAT-1 cadherin expression was elevated. MT KO CD11b(+) cells were more invasive than wild-type cells. CONCLUSIONS: MT plays an important role in collateral flow recovery and angiogenesis, an activity that appears to be mediated, in part, by the effects of MT on the functionality of 3 cell types essential for these processes: endothelial cells, smooth muscle cells, and macrophages.