Republication of "A Novel Casting Technique for Tongue-Type Calcaneus Fractures With Soft Tissue Compromise".

Displaced calcaneal fractures encompass a spectrum of fracture patterns, many of which are associated with soft tissue complications. Displaced tongue-type calcaneal fractures often cause pressure on the posterior heel skin, particularly when treatment is delayed. Resultant partial- or full-thickness skin necrosis presents significant challenges to the treating surgeon. In this article, the authors report on a case of full-thickness skin necrosis associated with a displaced tongue-type calcaneus fracture. The authors describe the use of a specialized heel window casting technique, which eliminates posterior heel pressure and greatly facilitates soft tissue surveillance and local wound care. The article also reviews the literature on soft tissue complications associated with displaced calcaneus fractures.

Factors influencing management of bilateral femur fractures: A multicenter retrospective cohort of early versus delayed definitive Fixation.

INTRODUCTION: The purpose of our study was to evaluate the factors that influence the timing of definitive fixation in the management of bilateral femoral shaft fractures and the outcomes for patients with these injuries. METHODS: Patients with bilateral femur fractures treated between 1998 to 2019 at ten level-1 trauma centers were retrospectively reviewed. Patients were grouped into early or delayed fixation, which was defined as definitive fixation of both femurs within or greater than 24 hours from injury, respectively. Statistical analysis included reversed logistic odds regression to predict which variable(s) was most likely to determine timing to definitive fixation. The outcomes included age, sex, high-volume institution, ISS, GCS, admission lactate, and admission base deficit. RESULTS: Three hundred twenty-eight patients were included; 164 patients were included in the early fixation group and 164 patients in the delayed fixation group. Patients managed with delayed fixation had a higher Injury Severity Score (26.8 vs 22.4; p<0.01), higher admission lactate (4.4 and 3.0; p<0.01), and a lower Glasgow Coma Scale (10.7 vs 13; p<0.01). High-volume institution was the most reliable influencer for time to definitive fixation, successfully determining 78.6% of patients, followed by admission lactate, 64.4%. When all variables were evaluated in conjunction, high-volume institution remained the strongest contributor (X2 statistic: institution: 45.6, ISS: 8.83, lactate: 6.77, GCS: 0.94). CONCLUSION: In this study, high-volume institution was the strongest predictor of timing to definitive fixation in patients with bilateral femur fractures. This study demonstrates an opportunity to create a standardized care pathway for patients with these injuries. LEVEL OF EVIDENCE: Level III.

Single-Stage Versus 2-Stage Bilateral Intramedullary Nail Fixation in Patients With Bilateral Femur Fractures: A Multicenter Retrospective Review.

OBJECTIVE: To evaluate rates of complications in patients with bilateral femur fractures treated with intramedullary nailing (IMN) during either 1 single procedure or 2 separate procedures. DESIGN: A multicenter retrospective review of patients sustaining bilateral femur fractures, treated with IMN in single or 2-stage procedure, from 1998 to 2018 was performed at 10 Level-1 trauma centers. SETTING: Ten Level-1 trauma centers. PATIENTS/PARTICIPANTS: Two hundred forty-six patients with bilateral femur fractures. INTERVENTIONS: Intramedullary nailing. MAIN OUTCOME MEASURES: Incidence of complications. RESULTS: A total of 246 patients were included, with 188 single-stage and 58 two-stage patients. Gender, age, injury severity score, abbreviated injury score, secondary injuries, Glasgow coma scale, and proportion of open fractures were similar between both groups. Acute respiratory distress syndrome (ARDS) occurred at higher rates in the 2-stage group (13.8% vs. 5.9%; P value = 0.05). When further adjusted for age, gender, injury severity score, abbreviated injury score, Glasgow coma scale, and admission lactate, the single-stage group had a 78% reduced risk for ARDS. In-hospital mortality was higher in the single-stage cohort (2.7% compared with 0%), although this did not meet statistical significance (P = 0.22). CONCLUSIONS: This is the largest multicenter study to date evaluating the outcomes between single- and 2-stage IMN fixation for bilateral femoral shaft fractures. Single-stage bilateral femur IMN may decrease rates of ARDS in polytrauma patients who are able to undergo simultaneous definitive fixation. However, a future prospective study with standardized protocols in place will be required to discern whether single- versus 2-stage fixation has an effect on mortality and to identify those individuals at risk. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Association of Perioperative Computed Tomography Hounsfield Units and Failure of Femoral Neck Fracture Fixation.

OBJECTIVES: To determine whether Hounsfield units (HUs) measured on perioperative computed tomographic scans are associated with radiographic outcomes and reoperations after femoral neck fracture fixation. DESIGN: Retrospective cohort study. SETTING: Level I trauma center. PATIENTS: One hundred fourteen patients age ≥18 years, who presented to a Level I trauma center, and who underwent surgical fixation of intracapsular femoral neck fracture and had perioperative computed tomographic scans and adequate follow-up. INTERVENTION: None. MAIN OUTCOME MEASUREMENTS: Screw penetration, femoral neck shortening >5 mm, and revision surgery. RESULTS: A median follow-up was 23 months. An HU measurement of the femoral head was significantly associated with screw penetration and femoral neck shortening but not revision surgery. Patients with middle femoral head HU measurements <146 had 17 times (95% confidence interval: 4.32-78.9, P < 0.001) increased odds of screw penetration. Greater than 5 mm shortening was seen in patients with HUs <212.5 in the low head section by an odds ratio of 7.8 (95% confidence interval: 2.15-33.0, P = 0.014). CONCLUSION: Outcome differences regarding screw penetration and femoral neck shortening related to the HU or densities of femoral head and neck at the time of fracture are significant. These findings can help the clinician with developing a treatment plan for either arthroplasty or fixation of a femoral neck fracture based on objective bone quality measurements rather than relying on an arbitrary age recommendation. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

A Reliable and Reproducible Critical-Sized Segmental Femoral Defect Model in Rats Stabilized with a Custom External Fixator.

Orthopedic research relies heavily on animal models to study mechanisms of bone healing in vivo as well as investigate the new treatment techniques. Critical-sized segmental defects are challenging to treat clinically, and research efforts could benefit from a reliable, ambulatory small animal model of a segmental femoral defect. In this study, we present an optimized surgical protocol for the consistent and reproducible creation of a 5 mm critical diaphyseal defect in a rat femur stabilized with an external fixator. The diaphyseal ostectomy was performed using a custom jig to place 4 Kirschner wires bicortically, which were stabilized with an adapted external fixator device. An oscillating bone saw was used to create the defect. Either a collagen sponge alone or a collagen sponge soaked in rhBMP-2 was implanted into the defect, and the bone healing was monitored over 12 weeks using radiographs. After 12 weeks, rats were sacrificed, and histological analysis was performed on the excised control and treated femurs. Bone defects containing only collagen sponge resulted in non-union, while rhBMP-2 treatment yielded the formation of a periosteal callous and new bone remodeling. Animals recovered well after implantation, and external fixation proved successful in stabilizing the femoral defects over 12 weeks. This streamlined surgical model could be readily applied to study bone healing and test new orthopedic biomaterials and regenerative therapies in vivo.

A role for MEIS1 in MLL-fusion gene leukemia.

Leukemias with MLL rearrangements are characterized by high expression of the homeobox gene MEIS1. In these studies, we knocked down Meis1 expression by shRNA lentivirus transduction in murine Mll-AF9 leukemia cells. Meis1 knockdown resulted in decreased proliferation and survival of murine Mll-AF9 leukemia cells. We also observed reduced clonogenic capacity and increased monocytic differentiation. The establishment of leukemia in transplantation recipients was significantly delayed by Meis1 knockdown. Gene expression profiling of cells transduced with Meis1 shRNA showed reduced expression of genes associated with cell cycle entry and progression. shRNA-mediated knockdown of MEIS1 in human MLL-fusion gene leukemia cell lines resulted in reduced cell growth. These results show that MEIS1 expression is important for MLL-rearranged leukemias and suggest that MEIS1 promotes cell-cycle entry. Targeting MEIS1 may have therapeutic potential for treating leukemias expressing this transcription factor.

Malignant transformation initiated by Mll-AF9: gene dosage and critical target cells.

The pathways by which oncogenes, such as MLL-AF9, initiate transformation and leukemia in humans and mice are incompletely defined. In a study of target cells and oncogene dosage, we found that Mll-AF9, when under endogenous regulatory control, efficiently transformed LSK (Lin(-)Sca1(+)c-kit(+)) stem cells, while committed granulocyte-monocyte progenitors (GMPs) were transformation resistant and did not cause leukemia. Mll-AF9 was expressed at higher levels in hematopoietic stem (HSC) than GMP cells. Mll-AF9 gene dosage effects were directly shown in experiments where GMPs were efficiently transformed by the high dosage of Mll-AF9 resulting from retroviral transduction. Mll-AF9 upregulated expression of 192 genes in both LSK and progenitor cells, but to higher levels in LSKs than in committed myeloid progenitors.