Skin Antisepsis before Surgical Fixation of Extremity Fractures.

BACKGROUND: Studies evaluating surgical-site infection have had conflicting results with respect to the use of alcohol solutions containing iodine povacrylex or chlorhexidine gluconate as skin antisepsis before surgery to repair a fractured limb (i.e., an extremity fracture). METHODS: In a cluster-randomized, crossover trial at 25 hospitals in the United States and Canada, we randomly assigned hospitals to use a solution of 0.7% iodine povacrylex in 74% isopropyl alcohol (iodine group) or 2% chlorhexidine gluconate in 70% isopropyl alcohol (chlorhexidine group) as preoperative antisepsis for surgical procedures to repair extremity fractures. Every 2 months, the hospitals alternated interventions. Separate populations of patients with either open or closed fractures were enrolled and included in the analysis. The primary outcome was surgical-site infection, which included superficial incisional infection within 30 days or deep incisional or organ-space infection within 90 days. The secondary outcome was unplanned reoperation for fracture-healing complications. RESULTS: A total of 6785 patients with a closed fracture and 1700 patients with an open fracture were included in the trial. In the closed-fracture population, surgical-site infection occurred in 77 patients (2.4%) in the iodine group and in 108 patients (3.3%) in the chlorhexidine group (odds ratio, 0.74; 95% confidence interval [CI], 0.55 to 1.00; P = 0.049). In the open-fracture population, surgical-site infection occurred in 54 patients (6.5%) in the iodine group and in 60 patients (7.3%) in the chlorhexidine group (odd ratio, 0.86; 95% CI, 0.58 to 1.27; P = 0.45). The frequencies of unplanned reoperation, 1-year outcomes, and serious adverse events were similar in the two groups. CONCLUSIONS: Among patients with closed extremity fractures, skin antisepsis with iodine povacrylex in alcohol resulted in fewer surgical-site infections than antisepsis with chlorhexidine gluconate in alcohol. In patients with open fractures, the results were similar in the two groups. (Funded by the Patient-Centered Outcomes Research Institute and the Canadian Institutes of Health Research; PREPARE ClinicalTrials.gov number, NCT03523962.).

Pediatric Supracondylar Fractures: Variation in Fracture Patterns and the Biomechanical Effects of Pin Configuration.

BACKGROUND: Transverse pediatric supracondylar fractures through the midolecranon fossa are frequently encountered and modeled in biomechanical studies. Our objective is to investigate the optimal pin configurations for low, sagittal oblique, and high fracture varieties that have not been previously investigated. METHODS: A total of 100 synthetic composite pediatric humeri were tested. Three groups of 30 were used to simulate 1 of 3 fracture variations. Subgroups of 10 were stabilized with 2 lateral pins (2LP), 3 lateral pins (3LP), or cross K-wires (XP). The 90 fracture and 10 intact models were tested for anterior posterior (AP), medial lateral (ML), and rotational stiffness. RESULTS: In low fractures, AP, ML, and rotational stiffness of 2LP and 3LP were similar to intact. ML stiffness was less using XP. AP and ML stiffness of 2LP and 3LP were significantly greater than XP.In oblique fractures, AP, ML, and rotational stiffness of 2LP was similar to intact but 3LP was significantly less. AP and ML stiffness of XP was significantly less. 2LP demonstrated greater AP, ML, and rotational stiffness than 3LP and XP.In high fractures, all configurations demonstrated significantly less rotational stiffness than intact and AP stiffness similar to intact. Rotational stiffness of 3LP was greater than 2LP and XP. AP and ML stiffness were not different among configurations. CONCLUSIONS: 2LP are stiffer than 3LP and XP for sagittal oblique fractures. 2LP and 3LP stiffness were similar in low transverse fractures, and both constructs demonstrated greater stiffness than XP configuration. 3LP is preferable for high transverse fractures. XP were never stiffer than the lateral only constructs in any of the patterns tested. CLINICAL RELEVANCE: All-lateral pin constructs may provide adequate stiffness to maintain reduction of low transverse, sagittal oblique, and high transverse patterns of pediatric supracondylar humerus fractures without risk of injury to the ulnar nerve.

Infection Rates and Surgical Procedures Associated With Isolated Open Talar Neck and Body Fractures.

BACKGROUND: Open fractures of the talar body and neck are uncommon. Previous reports of associated deep infection rates and resulting surgical requirements vary widely. The primary objective of this study is to report the incidence of deep infections for isolated open talar body and neck fractures, and secondarily the incidence and number of total surgeries performed (TSP), secondary salvage procedures (SSPs), and nonsalvage procedures (NSPs). METHODS: Retrospective case-control study of 32 consecutive isolated open talus fracture patients (22 neck, 10 body) were followed for an average of 39.2 months. RESULTS: Five (15.6%) fractures developed deep infections. Fifty percent of open body fractures became infected compared with 0% of neck fractures (P < .001). There was no difference between infected group (IG) and uninfected fracture group (UG) with respect to age, sex, body mass index, tobacco, diabetes, vascular disease, open fracture type, wound location, hours to irrigation and debridement, or definitive treatment. The majority (92.6%) of UG fractures used a dual incision with open wound extension. There were more single extensile approaches in the IG group (P = .04). The IG required 5.8 TSP per patient compared with 2.1 in the UG (P = .004). All (100%) of the IG required an SSP compared with 29.6% of the UG (P = .006). All (100%) of the IG required an NSP compared to 40.7% of the UG (P = .043). In the IG, 2.8 NSPs per patient were required after definitive surgery compared with 1.18 in the UG (P = .003). Of those followed 1 year, the incidence of SSP remained higher in the IG (P = .016). CONCLUSION: The incidence of deep infection following isolated open talar fractures is high and occurs disproportionally in body fractures. Infected fractures required nearly 6 surgeries, and all required SSP. LEVEL OF EVIDENCE: Level IV, prognostic.

A New Computed Tomography-Based Measure that Provides Insight Into Hip Stability in Patients With Posterior Wall Acetabular Fractures.

OBJECTIVES: To describe the technique and results of a new sagittal plane computed tomography (CT)-based angular measure for predicting stability after posterior wall acetabular fractures (PWF). DESIGN: Retrospective review. SETTING: Academic Level II trauma center. PATIENT SELECTION CRITERIA: Fifty-eight consecutive patients with PWF (AO/OTA class 62A.1), 98% were high-energy injuries. INTERVENTION: A new sagittal CT measure of PWF based on the angle subtending the joint center, cranial and caudal fracture exits. OUTCOME MEASURES AND COMPARISONS: Hip incongruity or dislocation demonstrated using gold standard test, examination under anesthesia (EUA), or instability on static images. Prediction of hip instability using a sagittal CT angular measure based on cranial and caudal fracture exits was compared with previous axial CT measures suggestive of increased risk for instability including posterior wall size >50%, and those with cranial exit within 5.0 mm of the acetabular dome. RESULTS: There were 32 operative and 26 nonoperatively treated fractures. Thirty fractures were determined to be unstable, and 28 were stable after EUA. Measurements of >70 degrees using the sagittal CT angular measure predicted instability in 28 of 28 patients, and ≤70 degrees predicted stability in 30 of 30 patients (sensitivity 100% and specificity 100%). Prevalence of EUA confirmed instability for subgroups with PWF based on prior axial CT measures were as follows: ≥50% wall involvement (11/16; sensitivity 67% and specificity 60%; 95% CI, 45%-89%/45%-75%), fracture within 5.0 mm of dome (5/18; sensitivity 86% and specificity 73%; 95% CI, 71%-100%/59%-87%), fracture within 5.0 mm of dome and ≥50% involvement (1/9; sensitivity 89% and specificity 56%; 95% CI, 69%-100%/24%-88%). CONCLUSIONS: In a sample of 58 mostly high energy posterior wall fractures all having had an EUA, a new sagittal angular CT measurement of ≤70 degrees predicted hip stability and >70 degrees predicted instability with 100% sensitivity and specificity. LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The Biomechanical Effects of Intramedullary Fixation to the Level of the Physeal Scar on Distal Tibia Fracture Stability.

INTRODUCTION: The purpose of this study was to evaluate whether intramedullary nail contact with physeal scar improves construct mechanics when treating distal tibial shaft fractures. METHODS: Axially unstable extra-articular distal tibia fractures were created in 30 fresh frozen cadaveric specimens (15 pairs, mean age 79 years). Specimens underwent intramedullary nailing to the level of the physeal scar locked with one or two interlocks or short of the physeal scar locked with two interlocks (reference group). Specimens were subjected to 800N of axial load for 25,000 cycles. Primary outcomes were stiffness before and after cyclic loading. Secondary outcomes were load to failure, load at 3 mm displacement, plastic deformation, and total deformation. RESULTS: The physeal scar with one interlock cohort demonstrated 3.8% greater stiffness before cycling ( P = 0.75) and 1.7% greater stiffness after cycling ( P = 0.86) compared with the reference group. The physeal scar with two interlocks group exhibited 0.3% greater stiffness before cycling ( P = 0.98) and 8.4% greater stiffness after cycling ( P = 0.41) in relation to the reference group. No differences were identified regarding load to failure or load at 3 mm displacement. In specimens with two interlocks, those in contact with the physeal scar demonstrated significantly less plastic ( P = 0.02) and total ( P = 0.04) deformation. CONCLUSIONS: Constructs ending at the physeal scar demonstrated stiffness and load to failure similar to those without physeal scar contact. Less plastic and total deformation was noted in two-interlock constructs with physeal scar contact, suggesting a possible protective effect provided by the physeal scar. These data argue that physeal scar contact may offer a small mechanical benefit in nailing distal tibia fractures, but clinical relevance remains unknown.

Patients With Cirrhosis Who Have a Model for End-stage Liver Disease Sodium Score of 8 or Greater Are at Increased Risk of Poor Outcomes in Operatively Treated Tibia Fractures.

The purpose of this study was to compare 30-day readmission rates for cirrhotic and non-cirrhotic patients after tibia fracture fixation by retrospectively identifying all surgically managed tibial plateau, tibial shaft, and pilon fractures from 2010 through 2018 in the National Surgical Quality Improvement Program database (N=14,028). The primary outcome measure was 30-day readmission rates. Secondary outcome measures included 30-day rates of reoperation, length of stay, pulmonary embolism, deep venous thrombosis, and wound complications, including deep or superficial infection. Cirrhotic patients (n=665) and non-cirrhotic patients (n=13,363) were identified using the aspartate aminotransferase to platelet ratio index test. Cirrhotic patients were more likely to have preoperative ascites, renal failure, bleeding disorders, and preoperative transfusions. No differences were reported between the two groups in readmission rate or any of the secondary outcome measures, except that cirrhotic patients' length of stay was longer by 0.5 day. Stratification of the cirrhotic cohort demonstrated that a Model for End-stage Liver Disease sodium (MELD-Na) score of 8 or greater was associated with a 4.1-fold increase in the rate of readmission (5.9% vs 1.5%; P<.01). No other differences were identified based on MELD-Na score stratification. Patients with advanced cirrhosis (MELD-Na score ≥8) have an increased risk of 30-day readmission after tibia fracture surgery. Cirrhosis associated with a lower MELD-Na score might not significantly increase the risk of 30-day complications in patients with tibia fractures. [Orthopedics. 2022;45(2):79-85.].

The impact of COVID-19 restrictions on participant enrollment in the PREPARE trial.

Background: At the initiation of the COVID-19 pandemic, restrictions forced researchers to decide whether to continue their ongoing clinical trials. The PREPARE (Pragmatic Randomized Trial Evaluating Pre-Operative Alcohol Skin Solutions in Fractured Extremities) trial is a pragmatic cluster-randomized crossover trial in patients with open and closed fractures. PREPARE was enrolling over 200 participants per month at the initiation of the pandemic. We aim to describe how the COVID-19 research restrictions affected participant enrollment. Methods: The PREPARE protocol permitted telephone consent, however, sites were obtaining consent in-person. To continue enrollment after the initiation of the restrictions participating sites obtained ethics approval for telephone consent scripts and the waiver of a signature on the consent form. We recorded the number of sites that switched to telephone consent, paused enrollment, and the length of the pause. We used t-tests to compare the differences in monthly enrollment between July 2019 and November 2020. Results: All 19 sites quickly implement telephone consent. Fourteen out of nineteen (73.6%) sites paused enrollment due to COVID-19 restrictions. The median length of enrollment pause was 46.5 days (range, 7-121 days; interquartile range, 61 days). The months immediately following the implementation of restrictions had significantly lower enrollment. Conclusion: A pragmatic design allowed sites to quickly adapt their procedures for obtaining informed consent via telephone and allowed for minimal interruptions to enrollment during the pandemic.

The effect of drill bit, pin, and wire tip design on drilling.

Successful penetration of bone is dependent on several factors, including bone quality, drill bit and pin design, and drilling technique. Wires are also used in bone drilling, and the tip configuration can affect the efficiency of bone penetration. Incorrect use of drill bits, pins, and wires may result in complications such as thermal necrosis and hardware breakage.

Medial sided articular impaction in tibial plateau fractures.

INTRODUCTION: Tibial plateau fractures are a heterogenous group of injuries with a variable amount of articular injury and are commonly associated with lateral sided articular impaction. Previous work has focused on describing the morphology of tibial plateau fractures, but has neglected description of medial sided articular impaction. The aim of this investigation was to assess the morphology of medial sided articular impaction in tibial plateau fractures, with specific attention directed toward the frequency, location, size, and associated fracture patterns. METHODS: Skeletally mature patients presenting to a Level I trauma center from 2008-2018 with a tibial plateau fracture (AO/OTA 41B-C) were identified retrospectively. Fractures were classified by AO/OTA and Schatzker type. Radiographs and computed tomography (CT) scans were reviewed to identify and localize medial sided articular impaction. The location and surface area of impaction was characterized by creating frequency diagram heat maps from axial CT scans. Descriptive statistics were performed using standard measures. RESULTS: Of the 1032 tibial plateau fractures included, 82 (7.9%) were noted to have medial sided articular impaction. Rate of impaction varied by fracture type (p = 0.03): Schatzker II, 2% (7 of 381); Schatzker IV, 21% (19 of 96); and Schatzker VI, 11% (56 of 524). Average total surface area of impaction was 9% of the total and 19% of the medial plateau area. Area of impaction varied by fracture type (p = 0.004): Schatzker II, 6% (95% confidence interval [CI], 4%-7%); Schatzker IV, 11% (95% CI, 9%-13%), and Schatzker VI, 9% (95% CI, 7%-11%). The area of impaction occurred primarily along the lateral aspect of the medial plateau in Schatzker II fractures, in the anteromedial quadrant of Schatzker IV fractures, and was evenly distributed across the medial plateau in Schatzker VI fractures. CONCLUSIONS: Surgeons should be aware that medial articular impaction is present in approximately 8% of tibial plateau fractures. Schatzker IV fractures are most likely to have medial impaction and a larger proportion of the joint surface involved in these injuries.

Do Fully Threaded Transiliac-Transsacral Screws Improve Mechanical Stability of Vertically Unstable Pelvic Fractures? A Cadaveric Biomechanical Analysis.

OBJECTIVE: To determine whether fully threaded transiliac-transsacral (TI-TS) fixation is biomechanically superior to partially threaded TI-TS fixation of vertically unstable transforaminal sacral fractures. METHODS: Vertically unstable zone 2 sacral fractures were created in 20 human cadaveric pelves with a unilateral osteotomy and resection of 1 cm of bone through the foramen of the sacrum to represent comminution. Ten specimens received either 2 7.3-mm fully threaded or 2 7.3-mm partially threaded TI-TS screw fixation at the S1 and S2 body, and every specimen received standard 3.5-mm 8-hole parasymphyseal plating anteriorly. Each pelvis was loaded to 250 N at 3 Hz for 100,000 cycles and then loaded to failure. The primary outcome was fracture displacement at the S1 foramen, which was measured at 25,000, 50,000, 75,000, and 100,000 cycles. Secondary outcomes were simulated clinical failure of ≥1 cm displacement at the S1 foramen to determine occurrence probability of failure, and load at failure was defined as 2.5 cm of the linear loading system displacement. Specimens in the fully threaded and partially threaded cohorts were otherwise respectively comparable in regards to age, gender, and bone density. RESULTS: Five of the 10 TI-TS partially threaded specimens experienced simulated clinical failure with >1 cm displacement at the S1 foramen compared with 0 of the 10 TI-TS fully threaded cohort (50% vs. 0%, P = 0.03). The mean maximal displacement at the S1 foramen was greater in the partially threaded cohort (9.3 mm) compared with the fully threaded cohort (3.6 mm; P = 0.004). Fully threaded specimens also demonstrated greater mean force to failure than the partially threaded specimens (461 N vs. 288 N; P = 0.0001). CONCLUSIONS: Fully threaded TI-TS screw fixation seems to be mechanically superior to partially threaded fixation in a cadaveric vertically unstable transforaminal sacral fracture model with significantly less displacement of the posterior pelvic ring and greater load to failure.

Polymethylmethacrylate: properties and contemporary uses in orthopaedics.

Polymethylmethacrylate (PMMA) has been used in orthopaedics since the 1940s. Despite the development and popularity of new biomaterials, PMMA remains popular. Although its basic components remain the same, small proprietary and environmental changes create variations in its properties. PMMA can serve as a spacer and as a delivery vehicle for antibiotics, and it can be placed to eliminate dead space. Endogenous and exogenous variables that affect its performance include component variables, air, temperature, and handling and mixing. PMMA is used in hip arthroplasty and vertebral augmentation, notably, vertebroplasty and kyphoplasty. Cardiopulmonary complications have been reported.

Ambulatory assistive devices in orthopaedics: uses and modifications.

Ambulatory assistive devices (eg, canes, crutches, walkers) provide advantages such as stability, augmentation of muscle action, and reduction of weight-bearing load. Although they are often prescribed, a detailed understanding of these devices is often lacking, which can lead to detrimental consequences. Comprehension of normal gait cadence, as well as the gait patterns used in both reciprocating and swinging gait, allows the orthopaedic surgeon to understand the limitations of the patient with gait abnormalities. Appreciating the types of assistive devices, their modifications, associated gait patterns, physiologic demand, proper fitting, and indications for use is essential in prescribing the proper device.

Pressure ulcers in orthopaedics.

Pressure ulcers can be a devastating complication in the care of orthopaedic patients. Their presence leads to increased morbidity, mortality, and cost of care. Therapy and rehabilitation cannot progress on a normal postoperative course in the patient with a pressure ulcer. Risk factors for the development of pressure ulcers include spinal cord injury, advanced age, and cognitive impairment. Several grading scales have been developed for the assessment of pressure ulcer. Frequent patient turning, close monitoring, and frequent skin checks are important factors in the prevention of pressure ulcer.

Waist-Hip Ratio Surrogate Is More Predictive Than Body Mass Index of Wound Complications After Pelvic and Acetabulum Surgery.

OBJECTIVES: To determine whether a novel surrogate of waist-hip ratio (WHR) is more predictive of wound complications after pelvis or acetabulum stabilization than body mass index (BMI) and describe the method of measuring a WHR proxy (WHRp). DESIGN: Retrospective review. SETTING: One Level 1 Trauma Center. PATIENTS: One hundred sixty-one patients after operative repair of pelvis and acetabulum fractures. INTERVENTION: Operative stabilization of a pelvic ring injury or acetabular fracture. MAIN OUTCOME MEASUREMENTS: Infection (pin, superficial, and deep) and wound healing complication. METHODS: We retrospectively reviewed 161 subjects after operative repair of pelvic and acetabular fractures. Primary outcome was any wound complication. BMI was acquired from medical records. WHRp was derived from anteroposterior and lateral computed tomography scout images. BMI and WHRp results were analyzed as continuous and categorical variables. BMI was grouped into high-risk categories of ≥30 and ≥40. WHRp data were grouped utilizing the WHO's high-risk profile for females (>0.85) and males (>0.90). An alternative optimal WHR was also assessed. Covariate analysis included demographic data, Injury Severity Score, mechanism, tobacco use, presence and types of open approach, injury type, associated injuries and comorbidities, failure of fixation, and thromboembolism. RESULTS: The mean follow-up was 15.9 months. Twenty-four (15%) patients developed wound complications. Increasing BMI (P < 0.007) and WHRp (P < 0.001) as continuous variables and female sex (P < 0.009) were associated with wound complications. Applying unadjusted continuous data to a receiver operating characteristic curve revealed a greater area under the curve for WHRp than for BMI (P < 0.001). The optimal predictive WHRp was ≥1.0 (P < 0.001, odds ratio 43.11). The receiver operating characteristic curve from adjusted data demonstrated a greater area under the curve for WHRp ≥1.0 (0.93) compared with BMI ≥30 (0.78) or ≥40 (0.75) and WHO WHRp (0.82). Computed tomography generated WHRp demonstrated excellent interrater reliability (0.99). CONCLUSION: The WHRp of ≥1.0 was more predictive than BMI of wound complications after operative treatment of pelvis and acetabulum fractures. In our series, WHRp calculated using scout images performed sufficiently well to predict wound complications. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Notch activation enhances mesenchymal stem cell sheet osteogenic potential by inhibition of cellular senescence.

Our previous studies have confirmed the therapeutic effects of mesenchymal stem cell (MSC) monolayer sheet transplantation on allograft repair. A limiting factor in their application is the loss of MSC multi-potency as a result of high density sheet culture-induced senescence. In the study reported in this article, we tested whether Notch activation could be used to prevent or delay sheet culture-induced cell aging. Our results showed that, during in vitro long-term (5-day) cell sheet culture, MSCs progressively lose their progenitor characteristics. In contrast, Notch activation by Jagged1 in MSC sheet culture showed reduced cellular senescence and cell cycle arrest compared with control MSCs without Notch activation. Importantly, knockdown of Notch target gene Hes1 totally blocked the inhibition effect of Jagged1 on cellular senescence. Finally, the in vivo allograft transplantation data showed a significant enhanced callus formation and biomechanical properties in Notch activation cultured long-term sheet groups when compared with long-term cultured sheet without Notch activation. Our results suggest that Notch activation by Jagged1 could be used to overcome the stem cell aging caused by high density sheet culture, thereby increasing the therapeutic potential of MSC sheets for tissue regeneration.

Improving Pain Management and Long-Term Outcomes Following High-Energy Orthopaedic Trauma (Pain Study).

Poor pain control after orthopaedic trauma is a predictor of physical disability and numerous negative long-term outcomes. Despite increased awareness of the negative consequences of poorly controlled pain, analgesic therapy among hospitalized patients after orthopaedic trauma remains inconsistent and often inadequate. The Pain study is a 3 armed, prospective, double-blind, multicenter randomized trial designed to evaluate the effect of standard pain management versus standard pain management plus perioperative nonsteroidal anti-inflammatory drugs or pregabalin in patients of ages 18-85 with extremity fractures. The primary outcomes are chronic pain, opioid utilization during the 48 hours after definitive fixation and surgery for nonunion in the year after fixation. Secondary outcomes include preoperative and postoperative pain intensity, adverse events and complications, physical function, depression, and post-traumatic stress disorder. One year treatment costs are also compared between the groups.

Residual Hole Orientation After Plate Removal: Effect on the Clavicle.

Clavicle fractures account for 2.6% to 4% of all fractures. Surgical stabilization of this type of injury is becoming more common. Anterior inferior plating and superior plating are 2 popular approaches to open reduction and internal fixation. Reports of plate removal have raised concerns about reinjury. The goal of the current study was to determine whether the orientation of screw holes in clavicles after removal of an anterior inferior plate vs a superior plate have different biomechanical effects on stiffness and load to failure. The medial and lateral ends of 28 matched pairs of fresh clavicles were potted. Pilot holes, 2.5 mm in diameter, were drilled and oriented anterior inferiorly or superiorly, simulating those left after removal of a plate for a middle-third fracture. The clavicles underwent dynamic axial compression and 3-point load to failure, replicating forces associated with reinjury. Clavicles with anterior inferior holes had a statistically significant higher median maximal load difference of 139 N compared with those with superior holes (P=.013). Anterior inferior holes showed a statistically significant median increase in stiffness of 16.3 N/mm compared with superior holes (P=.036). Clavicles with anterior inferior holes had a statistically significant increase in median maximal load to failure and an increase in median stiffness compared with those with superior holes. This finding is relevant for patients who undergo hardware removal and return to activities that put them at risk for repeat high-impact injuries to the clavicle.

Deletion of RBPJK in Mesenchymal Stem Cells Enhances Osteogenic Activity by Up-Regulation of BMP Signaling.

Recently we have demonstrated the importance of RBPjk-dependent Notch signaling in the regulation of mesenchymal stem cell (MSC) differentiation during skeletogenesis both in vivo and in vitro. Here we further performed RBPJK loss-of-function experiments to demonstrate for the first time that RBPJK deficient MSC shows enhanced differentiation and osteogenesis acts via up-regulation of the BMP signaling. In the present study, we first compared the spontaneous and osteogenic differentiation in normal and recombination signal binding protein for immunoglobulin kappa J region (RBPJK) deficient human bone marrow-derived mesenchymal stem cells (MSCs). It was found that RBPJK highly expressed in fresh isolated MSCs and its expression was progressing down-regulated during spontaneous differentiation and even greater in osteogenic media inducted differentiation. Deletion of RBPJK in MSCs not only enhances cell spontaneous differentiation, but also significantly accelerates condition media inducted osteogenic differentiation by showing enhanced alkaline phosphatase (ALP) activity, Alizarin red staining, gene expression of Runx2, Osteopontin (OPN), Type I collagen (COL1a1) in culture. Additionally, BMP signaling responsive reporter activity and phosphor-smad1/5/8 expression were also significantly increased upon removal of RBPJK in MSCs. These data proved that inhibition of Notch signaling in MSCs promotes cell osteogenic differentiation by up-regulation of BMP signaling, and RBPJK deficient MSC maybe a better cell population for cell-based bone tissue engineering.

A case of ipsilateral both bone forearm fracture and acute distal biceps rupture.

There have been no reports in the English literature of an acute distal biceps rupture with a diaphyseal forearm fracture. This report describes a case of the combined injuries associated with a compartment syndrome.

Anatomic relationships after instrumentation of the midshaft clavicle with 3.5-mm reconstruction plating: an anatomic study.

OBJECTIVES: To examine the anatomic relationships of the major neurovascular structures at the midshaft clavicle region as they pertain to plate osteosynthesis in the treatment of midshaft clavicle fractures. METHODS: Fifteen fresh cadaveric specimens were dissected at the clavicle region. The shortest distances from the midshaft clavicular fracture lines to the subclavian artery and vein and brachial plexus were measured with a digital caliper with the limb in anatomic position and at 90° of abduction. The mean and range distance values were recorded. The clavicles were then instrumented with eight-hole, 3.5-mm reconstruction plates and screws (Synthes, Paoli PA) placed in superior and anteroinferior positions. The shortest distances from the screw tips to the neurovascular structures were measured at variable plate positions, fracture zones, and limb positions. The incidence of screw tip contact was reported. RESULTS: In 20% (three of 15) of the specimens, screw tip contact with a major neurovascular structure occurred. In these three specimens, two screw tip contacts occurred with the plate in a superior position and two occurred with the plate in an anteroinferior position. In one specimen, screw tip contact occurred with both plate positions. Limb abduction to 90° consistently increased the distance of the neurovascular structures from the clavicle. There was no observable trend in screw contact frequency in respect to limb position or fracture zone. CONCLUSION: Caution must be exercised when instrumenting midshaft clavicle fractures regardless of chosen plate position. Limb abduction to 90° provides an added measure of safety during clavicle instrumentation.