Fracture healing in tibia fractures with an associated vascular injury

Effect of cranial tibial artery laceration on radiographic bone healing and perioperative complications in dogs undergoing tibial plateau leveling osteotomy

During tibial plateau leveling osteotomy (TPLO), the laceration of the cranial tibial artery (LCTA) may occur, and the ligation of the cranial tibial artery might lead to impaired blood supply to the osteotomy site. The present case-control study aimed to evaluate the effect of LCTA on TPLO healing and the occurrence of perioperative complications. The incidence and predisposing factors to LCTA were also investigated. Fourteen cases experiencing LCTA were retrospectively enrolled from medical records of two veterinary teaching hospitals (LCTA group), whereas 28 randomly selected TPLOs that did not experience LCTA were included in the control group. Signalment data, proximal tibial epiphysis conformation, osteotomy features, perioperative complications, and bone healing were compared between the two groups. Bone healing was evaluated using the modified radiographic union scale for tibial fracture and the visual analog scale. The mean incidence was 9.6%. Bodyweight was significantly higher in the LCTA group compared to the control group (P = 0.009). Dogs belonging to the LCTA groups were significantly younger (P = 0.01). Intraoperative hypotension was significantly overreported in the LCTA group (P = 0.0001). None of the other variables differed significantly between the two groups. Dogs' size seems to be a predisposing factor, with dogs weighing >15 kg having 22 times more chance of experiencing LCTA. Due to the well-developed collateral blood supply of the canine hindlimb, LCTA and the closure of the cranial tibial artery did not appear to delay the radiographic bone healing or affect the incidence of perioperative complications.

Predicting Union, Osteomyelitis, and Amputation Outcomes of Gustilo IIIC Open Tibial Fractures: A Retrospective Study

OBJECTIVE

Open tibial fractures are frequently encountered in high-energy traumas and can result in significant complications such as nonunion, osteomyelitis, and even amputation. Among open tibial fractures, Gustilo type IIIC cases are particularly challenging due to the concomitant occurrence of neurovascular injuries and soft tissue defects. This study aimed to assess factors that affect union time and complications in Gustilo IIIC tibial fractures.

METHODS

Patients who presented at our center with IIIC open tibial fractures from January 2000 to October 2020 were eligible for this retrospective analysis. Patient demographics, fracture characteristics, and the timing, number, and type of surgical intervention were documented. Outcomes of interest included union time, occurrence of osteomyelitis, and amputation. We performed univariate analyses including chi-squared test, Fischer's exact test, analysis of variance, and Kruskal-Wallis test based on the normality of the data and multivariate analyses including Cox proportional hazards model and logistic regression analyses.

RESULTS

Fifty-eight patients were enrolled and grouped by fracture healing time; eight had timely union (13.8%); 27 had late union (46.6%); eight had delayed union (13.8%); three had nonunion (5.2%); and 12 underwent amputation (20.7%). Nine fractures (15.5%) were complicated by osteomyelitis. Union time was prolonged in cases of triple arterial injury, distal third fractures, multiple trauma with injury severity score (ISS) ≥ 16 points, and increased bone defect length. Additionally, a bone gap >50 mm, diabetes mellitus, low body mass index, and triple arterial injury in the lower leg were significant risk factors for amputation. A time from injury to definitive soft tissue coverage of more than 22 days was the major risk factor for osteomyelitis. A scoring system to predict union time was devised and the predicted probability of union within 2 years was stratified based on this score.

CONCLUSION

IIIC tibial fractures involving the distal third of the tibia, fractures with bone defects, triple arterial injury, and multiple trauma with ISS ≥16 points demonstrated delayed union, and an effective prediction system for union time was introduced in this study. Early soft tissue coverage can reduce the risk of osteomyelitis. Finally, diabetes and severe bone and soft tissue defects pose a higher risk of amputation.

Use of Computed Tomography Angiography to Predict Complications in Tibia Fractures: A Multicenter Retrospective Analysis

OBJECTIVES

To assess the ability of computed tomography angiography identified infrapopliteal vascular injury to predict complications in tibia fractures that do not require vascular surgical intervention.

DESIGN

Multicenter retrospective review.

SETTING

Six Level I trauma centers.

PATIENTS AND INTERVENTION

Two hundred seventy-four patients with tibia fractures (OTA/AO 42 or 43) who underwent computed tomography angiography maintained a clinically perfused foot not requiring vascular surgical intervention and were treated with an intramedullary nail. Patients were grouped by the number of vessels below the trifurcation that were injured.

MAIN OUTCOME MEASUREMENTS

Rates of superficial and deep infection, amputation, unplanned reoperation to promote bone healing (nonunion), and any unplanned reoperation.

RESULTS

There were 142 fractures in the control (no-injury) group, 87 in the one-vessel injury group, and 45 in the two-vessel injury group. Average follow-up was 2 years. Significantly higher rates of nerve injury and flap coverage after wound breakdown were observed in the two-vessel injury group. The two-vessel injury group had higher rates of deep infection (35.6% vs. 16.9%, P = 0.030) and unplanned reoperation to promote bone healing (44.4% vs. 23.9%, P = 0.019) compared with controls, as well as increased rates of any unplanned reoperation compared with control and one-vessel injury groups (71.1% vs. 39.4% and 51.7%, P < 0.001), respectively. There were no significant differences in rates of superficial infection or amputation.

CONCLUSIONS

Tibia fractures with two-vessel injuries were associated with higher rates of deep infection and unplanned reoperation to promote bone healing compared with those without vascular injury, as well as increased rates of any unplanned reoperation compared with controls and fractures with one-vessel injury.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Admission lactate concentration has predictive value for death or severe complications within 30 days after admission in cattle with long-bone fractures

OBJECTIVE

To determine the prognostic value of lactate concentration measurements at admission in cattle with long-bone fractures.

ANIMALS

43 cattle with long-bone fractures between July 2016 and Dec 2018.

PROCEDURES

In this prospective cohort study, lactate concentration was measured in systemic venous blood and locally in capillary blood sampled from the fractured and contralateral limbs of cattle and assessed for outcome prediction. The cutoff value was determined by maximizing the Youden index from receiver-operating characteristic curves. Multivariable logistic regression was employed to verify whether higher lactate concentrations compared with the cutoff value were an independent risk factor for poor outcomes at 30 days or 3 years after admission.

RESULTS

Poor outcome was associated with higher capillary lactate concentration in the fractured limb (P < .001) and greater difference with systemic blood (P = .005). A cutoff value of lactate difference ≥ 2.4 mmol/L (sensitivity = 0.80; specificity = 0.965) between capillary lactate in the fractured limb and systemic blood was the best predictor of death ≤ 30 days after admission (P < .001). Multivariable analysis revealed that this cutoff value was an independent risk factor for 30-day and 3-year outcomes (P < .001).

CLINICAL RELEVANCE

Admission blood lactate concentration difference ≥ 2.4 mmol/L between the fractured limb and systemic blood was a robust and independent predictor of outcome for cattle of the present report. Lactate metabolism is locally impaired in fractured limbs of nonsurviving or at higher complication risk cattle, which may help identify patients at high risk for poor outcomes.

Serology and Comorbidities in Patients With Fracture Nonunion: A Multicenter Evaluation of 640 Patients

INTRODUCTION

This multicenter cohort study investigated the association of serology and comorbid conditions with septic and aseptic nonunion.

METHODS

From January 1, 2011, to December 31, 2017, consecutive individuals surgically treated for nonunion were identified from seven centers. Nonunion-type, comorbid conditions and serology were assessed.

RESULTS

A total of 640 individuals were included. 57% were male with a mean age of 49 years. Nonunion sites included tibia (35.2%), femur (25.6%), humerus (20.3%), and other less frequent bones (18.9%). The type of nonunion included septic (17.7%) and aseptic (82.3%). Within aseptic, nonvascular (86.5%) and vascular (13.5%) nonunion were seen. Rates of smoking, alcohol abuse, and diabetes mellitus were higher in our nonunion cohort compared with population norms. Coronary artery disease and tobacco use were associated with septic nonunion (P < 0.05). Diphosphonates were associated with vascular nonunion (P < 0.05). Serologically, increased erythrocyte sedimentation rate, C-reactive protein, parathyroid hormone, red cell distribution width, mean platelet volume (MPV), and platelets and decreased absolute lymphocyte count, hemoglobin, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and albumin were associated with septic nonunion while lower calcium was associated with nonvascular nonunion (P < 0.05). The presence of four or more of increased erythrocyte sedimentation rate, C-reactive protein, or red cell distribution width; decreased albumin; and age younger than 65 years carried an 89% positive predictive value for infection. Hypovitaminosis D was seen less frequently than reported in the general population, whereas anemia was more common. However, aside from hematologic and inflammatory indices, no other serology was abnormal more than 25% of the time.

DISCUSSION

Abnormal serology and comorbid conditions, including smoking, alcohol abuse, and diabetes mellitus, are seen in nonunion; however, serologic abnormalities may be less common than previously thought. Septic nonunion is associated with inflammation, younger age, and malnourishment. Based on the observed frequency of abnormality, routine laboratory work is not recommended for nonunion assessment; however, specific focused serology may help determine the presence of septic nonunion.

Risk of peripheral artery occlusive disease in patients with lower leg fracture who received fixation and non-fixation treatments: A population cohort study

Background

The risk of peripheral artery occlusive disease (PAOD) in patients with lower leg fracture who underwent fixation procedures is not yet completely understood. Therefore, the current study aimed to examine the risk of subsequent PAOD in patients with lower leg fracture who received fixation and non-fixation treatments.

Methods

We included 6538 patients with lower leg fracture who received non-fixation treatment and a matched cohort comprising 26152 patients who received fixation treatment from the National Health Insurance Database. Patients were frequency matched according to age, sex, and index year. The incidence and risk of PAOD in patients with lower leg fracture who received fixation and non-fixation treatments were evaluated via the stratification of different characteristics and comorbidities.

Results

Non-fixation treatment, male sex, older age (≥ 50 years old), diabetes mellitus, and gout were associated with a significantly higher risk of lower extremity PAOD compare to each comparison group, respectively. Moreover, there was a significant correlation between fixation treatment and a lower risk of lower extremity PAOD in women (adjusted hazard ratio [aHR] = 0.58, 95% confidence interval [CI] = 0.38–0.90), women aged > 50 years (aHR = 0.61, 95% CI = 0.38–0.96), and patients with coronary artery disease (aHR = 0.43, 95% CI = (0.23–0.81). Further, patients with fixation treatment had a significantly lower risk of lower extremity PAOD within 2 years after trauma (aHR = 0.57, 95% CI = 0.34–0.97). The Kaplan–Meier analysis showed that the cumulative incidence of PAOD was significantly higher in the non-fixation treatment group than in the fixation treatment group at the end of the 10-year follow-up period (log-rank test: P = 0.022).

Conclusion

Patients with lower leg fracture who received non-fixation treatment had a significantly higher risk of PAOD than those who received fixation treatment. Moreover, the risk of PAOD was higher in women aged > 50 years, as well as in coronary artery disease patients who received non-fixation treatment than in those who received fixation treatment. Therefore, regular assessment of vessel patency are recommended for these patients. Nevertheless, further studies must be conducted to validate the results of our study.

Femur Fracture With Arterial Injury in an 11-Year-Old Boy: A Case Report of a Rare Association

Post-traumatic vascular lesions of the lower extremity in children are uncommon and present some particularities in their management in comparison to those that occur in adults. Here, we report the case of an 11-year-old boy who presented with a diaphyseal fracture of the right femur associated with an injury of the homolateral superficial femoral artery after blunt trauma of the lower limb. The bone and the arterial injuries were surgically and successfully treated by an elastic stable centromedullary nailing and a venous bypass, respectively, with a good clinical and radiological evolution. The management of vascular injuries in childhood can be challenging and requires some special measures to avoid undesirable complications. Functional prognosis is generally described to be good if a rapid and adequate treatment is performed.

Base Deficit ≥ 6 within 24 h of Injury is a risk factor for fracture nonunion in the polytraumatized patient

BACKGROUND

Polytrauma patients are at risk for fracture nonunion, but the reasons are poorly understood. Increased base deficit (BD) is associated with hypovolemic shock. Although shock delays bone healing in animal models, there have been no clinical studies evaluating the impact of BD on nonunion risk.

MATERIALS AND METHODS

Patients age ≥ 16 with injury severity score > 16 that presented to an academic Level One trauma center with an operative femur or tibia fracture were reviewed. Clinical notes and radiographs were assessed to determine fracture healing status. Patient demographics, injury characteristics, BD, and number of packed red blood cell transfusions were recorded. Bivariate and multivariate analyses of multiple risk factors associated with nonunion were conducted to investigate the association of BD with nonunion.

RESULTS

The union group was comprised of 243 fractures; there were 36 fractures in the nonunion group. The following predictors were associated with nonunion: smoking (p = 0.009), alcohol use (p < 0.001), open fracture (p < 0.001), and treatment for deep infection at fracture site (p = 0.016). Additionally, worst BD over 24 h ≥ 6 (p = 0.031) was significant for nonunion development. A multivariate logistic regression analysis revealed worst BD ≥6 over 24 h remained significantly associated with the development of nonunion (odds ratio 3.02, p = 0.011) when adjusting for other risk factors.

CONCLUSIONS

A BD ≥ 6 within 24 h of admission was associated with a significantly increased risk of developing lower extremity fracture nonunion in polytrauma patients, even after adjusting for multiple other risk factors. Acute post-traumatic acidosis may have effects on long-term fracture healing.

A Case of Reconstruction of a Type IIIc Open Tibial Fracture with Bone Loss and Warm Ischemia Time of 13 Hours: Quality of Life and Review of the Literature

BACKGROUND The management of open Gustilo IIIC fractures can be challenging even for experienced orthopedic surgeons. The decision between limb salvage and amputation is extremely difficult and the scoring systems do not seem to affect it significantly. Although ischemic time has been proven to be a major factor, attempts at reconstruction of limbs with ischemic time over 6 hours have been made in past decades. A simultaneous management of skeletal, soft-tissues, and vascular injury should be performed. This requires an orthoplastic surgeon who is capable of doing all the necessary operations by him/herself with hand-surgery and microsurgery expertise. CASE REPORT We present a case of a 49-year-old man with a type IIIC open tibial fracture with bone loss and warm ischemia time of 13 hours, who underwent revascularization and reconstruction with good radiological and functional results after a follow-up of 3 years. A few similar cases have been presented in the literature but none of them had a combination of bone loss, severe soft tissue injury, and complete vascular disruption after a crush injury. CONCLUSIONS The treatment of type IIIC open fractures of the tibia can be a demanding and time-consuming process. Detailed information about the necessity of multiple surgical interventions must be explained and fully understood by the patient in order to have realistic expectations.

Injury of the Tibial Nutrient Artery Canal during External Fixation for Lower Extremity Fractures: A Computed Tomography Study

The tibial nutrient artery (TNA) is the major diaphyseal artery of the tibia supplying two thirds of the inner osseous cortex. Hence, iatrogenic injury of the TNA endangers the integrity of the tibial blood supply and may compromise fracture healing. The incidence of its injury in the setting of external fixation for lower limb fractures has not been previously investigated. The aim of this study was to evaluate the incidence of TNA injury in the context of external fixation and to characterize the topography of the fixator pins in relation to the TNA canal (TNAC). Patients who underwent external fixation for distal femoral fractures and for tibial (proximal, shaft, and distal) fractures and had a postoperative computed tomography study were retrospectively included. The following parameters were retrieved: 1) Pin characteristics (orientation and cortical position of the pins), 2) The anatomic relationship between the TNAC and external fixation pin (topography above/below and at the level of the TNAC, and the distance between the pin and medial tibial plateau and/or the medial malleolus), and 3) The incidence of TNAC injury (complete/partial disruption of TNA lumen). A total of 105 patients with 214 tibial pins were analyzed. In 27 patients (26%), the TNAC was completely injured by the pins of the external fixator. In 13 patients (12%), the TNAC was partially injured. Of the 214 analyzed pins, 85 pins (40%) were located at the level of the TNAC (the TNAC and the pin are seen on the same axial slice). Most pins that were applied at the level of the TNAC belonged to a knee-bridging external fixator. Of those, ninety-three percent of the pins were anteromedially applied according to published surgical guidelines. Six percent of the pins were applied through the tibial crest and 1% anterolaterally. Of those 85 pins, 42 pins (49%) injured the TNAC at least partially. Based on the analyzed pins and the incidence of partial and complete injury of the TNAC, we observed that the tibial segment at which the tibial nutrient artery is endangered was located approximately (95% CI: 13–15 cm) from the medial tibia plateau and (95% CI: 22–25 cm) from the medial malleolus. Thus, TNAC injury by external fixation pins in the context of lower limb fractures can be considered common. Almost half of the pins applied at the middle third of the tibia injured the TNA, despite adherence to published surgical guidelines for external fixation. When possible, pin application at the middle third of tibia should be avoided to circumvent iatrogenic injury of the TNA and to safeguard tibial blood supply.

The Effects of Cross-Border Transport on Patients With Tibia Fractures

BACKGROUND

Tibia fractures are common after trauma. Prior studies have shown that delays in treatment are associated with poor outcomes. A subpopulation of our patients are transported from Mexico, adding barriers to prompt care. We hypothesized that patients with tibia fractures crossing from Mexico would have delays in treatment and subsequently worse outcomes.

METHODS

The trauma registry of an American College of Surgeons-verified level 1 trauma center was retrospectively reviewed for all tibia fractures admitted from 2010 to 2015. Data collection included demographics, country of injury, characterization of injuries, interventions, complications, and outcomes. Patients were subdivided into those injured in the United States and in Mexico, and the two groups were compared.

RESULTS

A total of 498 patients were identified, 440 from the United States and 58 from Mexico. Mexico patients were more severely injured overall, with higher injury severity scores and a higher percentage of patients with abbreviated injury scale scores ≥3 for both head and chest regions. Mexico patients had longer times from injury to admission, as well as increased times to both debridement of open fractures and operative fixation after admission. On subgroup analysis of patients with isolated tibia fractures (other system abbreviated injury scale < 3), times from arrival to treatment and injury severity score were no longer statistically different.

CONCLUSIONS

Patients crossing the border from Mexico with tibia fractures have delays in time to admission and from admission to operative management, although this is primarily due to other severe injuries. Ongoing systems development is required to minimize delays in care and optimize outcomes.

How common are vascular injuries in open tibial fractures? A prospective longitudinal cohort study

BACKGROUND

Tibial fractures have an incidence of 15% of all adult fractures. They have been shown to have the highest incidence of non-union in long bone fractures and the highest incidence of vascular injury. Evidence from the literature suggests that a good vascular supply is important to ensure bone union. The aim of our study was to prospectively assess the incidence of vascular injuries in open tibial fractures and determine whether they were associated with an increased risk of non-union.

METHODS

We performed a prospective study to investigate the incidence of arterial injuries with computed tomography angiography (CTA) in patients with Gustilo-Anderson grade I-III open tibial fractures between 2013 and 2015. CTA was performed with the trauma series at acute admission and reported by two independent musculoskeletal radiologists. Patients were followed up with clinical and radiographic assessment for 1 year.

RESULTS

We recruited 77 patients into the study, and 56 patients (47 males, 9 females) were available for the final analysis, between 16 and 90 years of age. At the initial assessment, 29% had signs of arterial injury with active extravasation in 5%. The most common site of injury was in the diaphysis (87.5%), and the commonest mechanism was a road traffic accident. We found no significant relation between occult vascular injury and non-union (p > 0.05).

CONCLUSION

The incidence of vascular injury in open tibial fractures is 29%, and CTA is therefore a useful test in identifying vascular injuries that may require vascular intervention.

Tendon healing in the context of complex fractures

Tendons connect muscle to bone and play an integral role in bone and joint alignment and loading. Tendons act as pulleys that provide anchorage of muscle forces for joint motion and stability, as well as for fracture reduction and realignment. Patients that experience complex fractures also have concomitant soft tissue injuries, such as tendon damage or rupture. Tendon injuries that occur at the time of bone fracture have long-term ramifications on musculoskeletal health, yet these injuries are often disregarded in clinical treatment and diagnosis for patients with bone fractures as well as in basic science approaches for understanding bone repair processes. Delayed assessment of soft tissue injuries during evaluation of trauma can lead to chronic pain, dysfunction, and delayed bone healing even following successful fracture repair, highlighting the importance of identifying and treating damaged tendons early. Treatment strategies for bone repair, such as mechanical stabilization and biological therapeutics, can impact tendon healing and function. Because poor tendon healing following complex fracture can significantly impact the function of tendon during bone fracture healing, a need exists to understand the healing process of complex fractures more broadly, beyond the healing of bone. In this review, we explored the mechanical and biological interaction of bone and tendon in the context of complex fracture, as well as the relevance and potential ramifications of tendon damage following bone fracture, which has particular impact on patients that experience complex fractures, such as from combat, automobile accidents, and other trauma.

Prediction of tibial nonunion at the 6-week time point

INTRODUCTION

Intramedullary (IM) nail fixation is a common operative treatment, yet concerns regarding the frequency of complications, such as nonunion, remain. Treatment of tibial shaft fractures remains a challenge, and little evidence of prognostic factors that increase risk of nonunion is available. The aim of this study was to develop a predictive model of tibial shaft fracture nonunion 6 weeks after reamed intramedullary (IM) nail fixation based on commonly collected clinical variables and the radiographic union score for tibial fractures (RUST).

METHODS

A retrospective case-control study was conducted. All tibial shaft fractures treated at our level I trauma center from 2007 to 2014 were retrospectively reviewed. Only patients with follow-up until fracture healing or secondary operation for nonunion were included. Fracture gaps ≥3 mm were excluded. A total of 323 patients were included for study.

RESULTS

Infection within 6 weeks of operation, standard RUST, and the Nonunion Risk Determination (NURD) score had statistically significant associations with nonunion (odds ratio > or < 1.0; p < 0.01). The NURD score was increasingly predictive of nonunion with decreasing RUST. All patients in the high RUST group (RUST ≥ 10), achieved union regardless of NURD score. In the medium RUST group (RUST 6-9), 25% of patients with a NURD score ≥7 experienced nonunion. In the low RUST group (RUST <6 or infection within 6 weeks), 69% of patients with a NURD score ≥7 experienced nonunion.

CONCLUSION

Three variables predicted nonunion. Based on these variables, we created a clinical prediction tool of nonunion that could aid in clinical decision making and discussing prognosis with patients.

Risk Factors for Failure of Bone Grafting of Tibia Nonunions and Segmental Bone Defects: A New Preoperative Risk Assessment Score

OBJECTIVE

To develop a clinically useful prediction model of success at the time of surgery to promote bone healing for established tibial nonunion or traumatic bone defects.

DESIGN

Retrospective case controlled.

SETTING

Level 1 trauma center.

PATIENTS

Adult patients treated with surgery for established tibia fracture nonunion or traumatic bone defects from 2007 to 2016. Two hundred three patients met the inclusion criteria and were available for final analysis.

INTERVENTION

Surgery to promote bone healing of established tibia fracture nonunion or segmental defect with plate and screw construct, intramedullary nail fixation, or multiplanar external fixation.

MAIN OUTCOME MEASURES

Failure of the surgery to promote bone healing that was defined as unplanned revision surgery for lack of bone healing or deep infection. No patients were excluded who had a primary outcome event.

RESULTS

Multivariate logistic modeling identified 5 significant (P < 0.05) risk factors for failure of the surgery to promote bone healing: (1) mechanism of injury, (2) Increasing body mass index, (3) cortical defect size (mm), (4) flap size (cm), and (5) insurance status. A prediction model was created based on these factors and awarded 0 points for fall, 17 points for high energy blunt trauma (OR = 17; 95% CI, 1-286, P = 0.05), 22 points for industrial/other (OR = 22; 95% CI, 1-4, P = 0.04), and 28 points for ballistic injuries (OR = 28; 95% CI, 1-605, P = 0.04). One point is given for every 10 cm of flap size (OR = 1; 95% CI, 1-1.1, P < 0.001), 10 mm of mean cortical gap distance (OR = 1; 95% CI, 1-2, P = 0.004), and 10 units BMI, respectively (OR = 1.5; 95% CI, 1-3, P = 0.16). Two points are awarded for Medicaid or no insurance (OR = 2; 95% CI, 1-5, P = 0.035) and 3 points for Medicare (3; 95% CI, 1-9, P = 0.033). Each 1-point increase in risk score was associated with a 6% increased chance of requiring at least 1 revision surgery (P < 0.001).

CONCLUSIONS

This study presents a clinical score that predicts the likelihood of success after surgery for tibia fracture nonunions or traumatic bone defects and may help clinicians better determine which patients are likely to fail these procedures and require further surgery.

miR-628-3p regulates osteoblast differentiation by targeting RUNX2: Possible role in atrophic non-union

Atrophic non-union is a serious complication of fractures. The underlying biological mechanisms involved in its pathogenesis are not yet completely understood. MicroRNAs (miRNAs or miRs) are a type of endogenous small non-coding RNA, which participate in various physiological and pathophysiological processes. In this study, differentially expressed miRNAs were screened in patients with atrophic nonunion. In total, 4 miRNAs (miR-149^*, miR-221, miR-628-3p and miR-654-5p) were upregulated and 7 miRNAs (let-7b^*, miR-220b, miR-513a-3p, miR-551a, miR-576-5p, miR-1236 and kshv-miR-K12-6-5p) were downregulated at the fracture sites in patients with atrophic non-union. Among the upregulated miRNAs, miR-628-3p and miR-654-5p expression was found to be persistently decreased during osteoblast differentiation, indicating their possible inhibitory effect on osteogenesis. Gain-of-function experiment demonstrated that miR-628-3p, but not miR-654-5p, attenuated osteoblast differentiation. Further, in silico analysis revealed that runt-related transcription factor 2 (RUNX2), the master transcript factor for osteoblast differentiation, was the target of miR-628-3p, which had two binding site-condense regions in the 3′ untranslated region. The exact binding site of miR-628-3p was further identified with luciferase reporter assay. In addition, the overexpression of miR-628-3p appeared to be associated with the suppression of RUNX2 expression at both the mRNA and protein level, suggesting that miR-628-3p inhibits osteoblast differentiation via RUNX2. On the whole, the findings of this study provide evidence of the upregulation of miR-628-3p in patients with atrophic non-union and that miR-628-3p may exert an inhibitory effect on osteogenesis via the suppression of its target gene, RUNX2. The study provides valuable insight into the pathogenesis of atrophic non-union and suggests new potential therapeutic targets for the treatment of this disorder.

Targeting the hypoxic response in bone tissue engineering: A balance between supply and consumption to improve bone regeneration

Bone tissue engineering is a promising therapeutic alternative for bone grafting of large skeletal defects. It generally comprises an ex vivo engineered combination of a carrier structure, stem/progenitor cells and growth factors. However, the success of these regenerative implants largely depends on how well implanted cells will adapt to the hostile and hypoxic host environment they encounter after implantation. In this review, we will discuss how hypoxia signalling may be used to improve bone regeneration in a tissue-engineered construct. First, hypoxia signalling induces angiogenesis which increases the survival of the implanted cells as well as stimulates bone formation. Second, hypoxia signalling has also angiogenesis-independent effects on mesenchymal cells in vitro, offering exciting new possibilities to improve tissue-engineered bone regeneration in vivo. In addition, studies in other fields have shown that benefits of modulating hypoxia signalling include enhanced cell survival, proliferation and differentiation, culminating in a more potent regenerative implant. Finally, the stimulation of endochondral bone formation as a physiological pathway to circumvent the harmful effects of hypoxia will be briefly touched upon. Thus, angiogenic dependent and independent processes may counteract the deleterious hypoxic effects and we will discuss several therapeutic strategies that may be combined to withstand the hypoxia upon implantation and improve bone regeneration.

Prognostic Factors of Leg Amputation in Patients With Vascular Injury: A Systematic Review

Individual studies on the prognostic factors of leg amputation, due to vascular injury, have been small, and they have produced conflicting results. Reliable data are necessary so that surgery can be targeted more effectively. The authors carried out a systematic review from 1990 to 2002 to identify the high risk of patients to amputation. Meta-analysis was carried out. The authors found that patients with preoperative hypotension, popliteal artery injury, and associated bone and nerve injury had a significantly higher risk of leg amputation than those without these risk factors. Also, patients with postoperative infection had a higher chance of amputation than those without infection. This information is essential for an appropriate evaluation and the treatment of such patients.

Will My Tibial Fracture Heal? Predicting Nonunion at the Time of Definitive Fixation Based on Commonly Available Variables

BACKGROUND

Accurate prediction of tibial nonunions has eluded researchers. Reliably predicting tibial nonunions at the time of fixation could change management strategies and stimulate further research.

QUESTIONS/PURPOSES

We asked (1) whether data from medical records, fracture characteristics, and radiographs obtained at the time of fixation would identify features predictive of tibial fracture nonunion; and (2) whether this information could be used to create a model to assess the chance of nonunion at the time of intramedullary (IM) nail fixation of the tibia.

METHODS

We retrospectively reviewed all tibial shaft fractures treated at our center from 2007 to 2014. We conducted a literature review and collected data on 35 factors theorized to contribute to delayed bone healing. Patients were followed to fracture healing or surgery for nonunion. Patients with planned prophylactic nonunion surgery were excluded because their nonunions were anticipated and our focus was on unanticipated nonunions. Our cohort consisted of 382 patients treated with IM nails for tibial shaft fractures (nonunion, 56; healed, 326). Bivariate and multivariate regression techniques and stepwise modeling approaches examined the relationship between variables available at definitive fixation. Factors were included in our model if they were identified as having a modest to large effect size (odds ratio > 2) at the p < 0.05 level.

RESULTS

A multiple variable logistic regression model was developed, including seven factors (p < 0.05; odds ratio > 2.0). With these factors, we created the Nonunion Risk Determination (NURD) score. The NURD score assigns 5 points for flaps, 4 points for compartment syndrome, 3 points for chronic condition(s), 2 points for open fractures, 1 point for male gender, and 1 point per grade of American Society of Anesthesiologists Physical Status and percent cortical contact. One point each is subtracted for spiral fractures and for low-energy injuries, which were found to be predictive of union. A NURD score of 0 to 5 had a 2% chance of nonunion; 6 to 8, 22%; 9 to 11, 42%; and > 12, 61%.

CONCLUSIONS

The proposed nonunion prediction model (NURDS) seems to have potential to allow clinicians to better determine which patients have a higher risk of nonunion. Future work should be directed at prospectively validating and enhancing this model.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Risk factors for long bone fracture non-union: a stratification approach based on the level of the existing scientific evidence

Non-union continues to be the most devastating complication after fracture fixation. Its treatment can be prolonged and often unpredictable. The burden to the patient, surgeon and health care system can be immense. Strategies to prevent it and or identify early its development are desirable in order to improve the clinical course of the affected patients and their outcomes. We undertook a systematic review of the literature in order to identify the most common and important risk factors based on the hierarchy of level of evidence. Accordingly, a stratification scale was formed which highlighted 10 risk factors including; an open method of fracture reduction, open fracture, presence of post-surgical fracture gap, smoking, infection, wedge or comminuted types of fracture, high degree of initial fracture displacement, lack of adequate mechanical stability provided by the implant used, fracture location in the poor zone of vascularity of the affected bone, and the presence of the fracture in the tibia. Clinicians should take in to account these findings when managing patients with long bone fractures, particularly the femur and tibia in order to minimise the risk of non-union.

HIF-1α-induced microRNA-210 reduces hypoxia-induced osteoblast MG-63 cell apoptosis

To better understand the ischemic-hypoxia-induced fracture healing impairment, we determined in this study the microRNA-210 expression in broken bone specimens and in osteoblasts under hypoxia and then determined the influence of microRNA-210 overexpression on the osteoblast cell proliferation and apoptosis. Results demonstrated that microRNA-210 expression was upregulated with an association with HIF-1α overexpression in clinical human catagmatic tissues and was upregulated HIF-1α-dependently in response to hypoxia in osteoblast MG-63 cells. CCK-8 assay indicated that microRNA-210 upregulation by microRNA-210 mimics reduced the chemotherapeutic 5-FU-induced osteoblast cell death, and colony formation assay demonstrated that microRNA-210 mimics promoted osteoblast cells growth. Moreover, the microRNA-210 mimics transfection inhibited the hypoxia-induced MG-63 cell apoptosis via inhibiting the activation of caspase 3 and caspase 9. Therefore, our research indicated a protective role of microRNA-210 in response to hypoxia. And microRNA-210 might serve as a protective role in bone fracture healing.

Location of civilian ballistic femoral fracture indicates likelihood of arterial injury

BACKGROUND

We evaluated whether the location of a ballistic femoral fracture helps predict the presence of arterial injury. We hypothesized that fractures located in the distal third of the femur are associated with a higher rate of arterial injury.

METHODS

We conducted a retrospective review of electronic medical records at our level I trauma centre and found 133 consecutive patients with femoral fractures from civilian gunshots from 2002 to 2007, 14 of whom sustained arterial injury. Fracture extent was measured with computerized viewing software and recorded with a standard technique, calculating proximal, distal, and central locations of the fracture as a function of overall length of the bone. Analyses were conducted with Student's t, Chi-squared, and Fisher's exact tests.

RESULTS

The location of any fracture line in the distal third of the femur was associated with increased risk of arterial injury (P<0.05). The odds ratio for the presence of arterial injury when the proximal fracture line was in the distal third of the femur was 5.63 (95% confidence interval, 1.7-18.6; P<0.05) and when the distal fracture line was in the distal third of the femur was 6.72 (95% confidence interval, 1.78-25.44; P<0.05).

CONCLUSIONS

A fracture line in the distal third of the femur after ballistic injury is six times more likely to be associated with arterial injury and warrants careful evaluation. Our data show that fracture location can help alert clinicians to possible arterial injury after ballistic femoral fracture.

Cigarette smoking and its impact on fracture healing

In this review, we discuss current knowledge and studies concerning the pathophysiology of cigarette smoking and its impact on fracture healing. We include studies on the biology of fracture healing and more specifically how smoking affects oxygenation in tissues, serum concentrations of important growth factors, collagen synthesis, and bone mineralization. Also mentioned are clinical studies showing that smoking impacts soft tissue regeneration and the healing of tibial fractures and open fractures, as well as articles discussing the apparent benefits and limitations of presurgical smoking cessation. Our review of the current literature suggests that it is necessary to inform smokers with fractures about their increased risk for impaired fracture healing. They should be closely monitored and additional therapies such as the use of BMP-7, BMP-2, or low-intensity ultrasound should be considered in early stages after trauma.

Recovery from hind limb ischemia enhances rhBMP-2-mediated segmental bone defect repair in a rat composite injury model

Although severe extremity trauma is often inclusive of skeletal and vascular damage in combination, segmental bone defect repair with concomitant vascular injury has yet to be experimentally investigated. To this end, we developed a novel rat composite limb injury model by combining a critically-sized segmental bone defect with surgically-induced hind limb ischemia (HLI). Unilateral 8mm femoral defects were created alone (BD) or in combination with HLI (BD + HLI), and all defects were treated with rhBMP-2 via a hybrid biomaterial delivery system. Based on reported clinical and experimental observations on the importance of vascular networks in bone repair, we hypothesized that HLI would impair bone regeneration. Interestingly, the BD+HLI group displayed improved radiographic bridging, and quantitative micro-CT analysis revealed enhanced bone regeneration as early as week 4 (p < 0.01) that was sustained through week 12 (p < 0.001) and confirmed histologically. This effect was observed in two independent studies and at two different doses of rhBMP-2. Micro-CT angiography was used to quantitatively evaluate vascular networks at week 12 in both the thigh and the regenerated bone defect. No differences were found between groups in total blood vessel volume in the thigh, but clear differences in morphology were present as the BD+HLI group possessed a more interconnected network of smaller diameter vessels (p < 0.001). Accordingly, while the overall thigh vessel volume was comparable between groups, the contributions to vessel volume based on vessel diameter differed significantly. Despite this evidence of a robust neovascular response in the thigh of the BD + HLI group, differences were not observed between groups for bone defect blood vessel volume or morphology. In total, our results demonstrate that a transient ischemic insult and the subsequent recovery response to HLI significantly enhanced BMP-2-mediated segmental bone defect repair, providing additional complexity to the relationship between vascular tissue networks and bone healing. Ultimately, a better understanding of the coupling mechanisms may reveal important new strategies for promoting bone healing in challenging clinical scenarios.

Disruption of thrombospondin-2 accelerates ischemic fracture healing

Thrombospondin-2 (TSP2) is a matricellular protein that is highly up-regulated during fracture healing. TSP2 negatively regulates vascularity, vascular reperfusion following ischemia, and cutaneous wound healing. As well, TSP2-null mice show increased endocortical bone formation due to an enhanced number of mesenchymal progenitor cells and show increased cortical thickness. Mice deficient in TSP2 (TSP2-null) show an alteration in fracture healing, that is unrelated to their cortical bone phenotype, which is characterized by enhanced vascularization with a shift towards an intramembranous healing phenotype; thus, we hypothesized that there would be enhanced ischemic fracture healing in the absence of TSP2. We investigated whether an absence of TSP2 would enhance ischemic fracture healing utilizing Laser doppler, µCT and histological analysis. Ischemic tibial fractures were created in wildtype (WT) and TSP2-null mice and harvested 10, 20, or 40 days post-fracture. TSP2-null mice show enhanced vascular perfusion following ischemic fracture. At day 10 post-fracture, TSP2-null mice have 115% greater bone volume than WT mice. This is associated with a 122% increase in vessel density, 20% increase in cell proliferation, and 15% decrease in apoptosis compared to WT. At day 20, TSP2-null mice have 34% more bone volume, 51% greater bone volume fraction, and 37% more bone tissue mineral density than WT. By 40 days after fracture the TSP2-null mice have a 24% increase in bone volume fraction, but other parameters show no significant differences. These findings indicate TSP2 is a negative regulator of ischemic fracture healing and that in the absence of TSP2 bone regeneration is enhanced.

The role of oxygen during fracture healing

Oxygen affects the activity of multiple skeletogenic cells and is involved in many processes that are important for fracture healing. However, the role of oxygen in fracture healing has not been fully studied. Here we systematically examine the effects of oxygen tension on fracture healing and test the ability of hyperoxia to rescue healing defects in a mouse model of ischemic fracture healing. Mice with tibia fracture were housed in custom-built gas chambers and groups breathed a constant atmosphere of 13% oxygen (hypoxia), 21% oxygen (normoxia), or 50% oxygen (hyperoxia). The influx of inflammatory cells to the fracture site, stem cell differentiation, tissue vascularization, and fracture healing were analyzed. In addition, the efficacy of hyperoxia (50% oxygen) as a treatment regimen for fracture nonunion was tested. Hypoxic animals had decreased tissue vascularity, decreased bone formation, and delayed callus remodeling. Hyperoxia increased tissue vascularization, altered fracture healing in un-complicated fractures, and improved bone repair in ischemia-induced delayed fracture union. However, neither hypoxia nor hyperoxia significantly altered chondrogenesis or osteogenesis during early stages of fracture healing, and infiltration of macrophages and neutrophils was not affected by environmental oxygen after bone injury. In conclusion, our results indicate that environmental oxygen levels affect tissue vascularization and fracture healing, and that providing oxygen when fractures are accompanied by ischemia may be beneficial.

Gustilo IIIC fractures in the lower limb: our 15-year experience

Controversy continues to surround the management of patients with an open fracture of the lower limb and an associated vascular injury (Gustilo type IIIC). This study reports our 15-year experience with these fractures and their outcome in 18 patients (15 male and three female). Their mean age was 30.7 years (8 to 54) and mean Mangled Extremity Severity Score (MESS) at presentation was 6.9 (3 to 10). A total of 15 lower limbs were salvaged and three underwent amputation (two immediate and one delayed). Four patients underwent stabilisation of the fracture by external fixation and 12 with an internal device. A total of 11 patients had damage to multiple arteries and eight had a vein graft. Wound cover was achieved with a pedicled flap in three and a free flap in six. Seven patients developed a wound infection and four developed nonunion requiring further surgery. At a mean follow-up of five years (4.1 to 6.6) the mean visual analogue scale for pain was 64 (10 to 90). Depression and anxiety were common. Activities were limited mainly because of pain, and the MESS was a valid predictor of the functional outcome. Distal tibial fractures had an increased rate of nonunion when associated with posterior tibial artery damage, and seven patients (39%) were not able to return to their previous occupation.

Is non-union of tibial shaft fractures due to nonculturable bacterial pathogens? A clinical investigation using PCR and culture techniques

BACKGROUND

Non-union continues to be one of the orthopedist's greatest challenges. Despite effective culture methods, the detection of low-grade infection in patients with non-union following tibial fracture still presents a challenge. We investigated whether "aseptic" tibial non-union can be the result of an unrecognized infection.

METHODS

A total of 23 patients with non-union following tibial shaft fractures without clinical signs of infection were investigated. Intraoperative biopsy samples obtained from the non-union site were examined by means of routine culture methods and by polymerase chain reaction (PCR) for the detection of 16 S ribosomal RNA (rRNA). Control subjects included 12 patients with tibial shaft fractures.

RESULTS

23 patients (8 women and 15 men; mean age: 47.4 years) were included into this study. Preoperative C-reactive protein levels (mean: 20.8 mg/l) and WBC counts (mean: 8,359/μl) in the study group were not significantly higher than in the control group. None of the samples of non-union routine cultures yielded microorganism growth. Bacterial isolates were found by conventional culturing methods in only 1 case of an open fracture from the control group. In this case, PCR yielded negative results. 16 S rRNA was detected in tissue specimens from 2 patients (8.7%) with non-union. The analysis of these variable species-specific sequences enabled the identification of specific microorganisms (1x Methylobacterium species, 1x Staphylococcus species). Both PCR-positive patients were culture-negative.

CONCLUSIONS

The combination of microbiological culture and broad-range PCR seems to substantially add to the number of microbiological diagnoses obtained and may improve the clinician's ability to tailor therapy to the individual patient's needs.

The anaphylatoxin receptor C5aR is present during fracture healing in rats and mediates osteoblast migration in vitro

BACKGROUND

There is evidence that complement components regulate cytokine production in osteoblastic cells, induce cell migration in mesenchymal stem cells, and play a regulatory role in normal enchondral bone formation. We proved the hypothesis that complement might be involved in bone healing after fracture.

METHODS

We investigated the expression of the key anaphylatoxin receptor C5aR during fracture healing in rats by immunostaining after 1, 3, 7, 14, and 28 days. C5aR expression was additionally analyzed in human mesenchymal stem cells (hMSC) during osteogenic differentiation, in human primary osteoblasts, and osteoclasts by reverse transcriptase polymerase chain reaction and immunostaining. Receptor functionality was proven by the migratory response of cells to C5a in a Boyden chamber.

RESULTS

C5aR was expressed in a distinct spatial and temporal pattern in the fracture callus by differentiated osteoblast, chondroblast-like cells in cartilaginous regions, and osteoclasts. In vitro C5aR was expressed by osteoblasts, osteoclasts, and hMSC undergoing osteogenic differentiation. C5aR was barely expressed by undifferentiated hMSC but was significantly induced after osteogenic differentiation. C5aR activation by C5a induced strong chemotactic activity in osteoblasts, and in hMSC, which had undergone osteogenic differentiation, being abolished by a specific C5aR antagonist. In hMSC, C5a induced less migration reflecting their low level of C5aR expression.

CONCLUSIONS

Our in vitro and in vivo results demonstrated the presence of C5aR in bone forming osteoblasts and bone resorbing osteoclasts. It is suggested that C5aR might play a regulatory role in fracture healing in intramembranous and in enchondral ossification, one possible function being the regulation of cell recruitment.

Blast-induced lower extremity fractures with arterial injury: prevalence and risk factors for amputation after initial limb-preserving treatment

OBJECTIVES

The purpose of this study is to determine the rate of late (secondary) amputation and to identify risk factors for amputation in injuries that were initially treated with limb preservation on the battlefield.

METHODS

A retrospective review at our institution identified 24 consecutive patients with 26 blast-induced open fractures distal to the joint that had associated arterial injuries. All injuries were initially cared for on the battlefield and during the evacuation chain of care with limb preservation protocols. All definitive orthopaedic care was provided by a single fellowship-trained orthopaedic trauma surgeon at a tertiary care stateside facility. Injury factors were analyzed based on radiographic and chart review to determine associations with amputation.

RESULTS

Twenty of 26 injured limbs received an amputation for a total amputation rate of 76.9% (95% confidence interval, 57.9-88.9%). Fourteen limbs received early amputation before limb salvage attempts. Six of the 12 limbs that received limb salvage underwent late amputation.

CONCLUSIONS

The rate of amputation in severe blast-induced extremity fractures combined with an arterial injury initially treated with limb preservation on the battlefield and before transfer to the definitive military treatment facility is extremely high. Blast-injured lower limbs with a combined severe bony and soft tissue injury should be carefully assessed when arterial injury is present because they may require early amputation during initial surgical care on the battlefield.

Vascular injury associated with extremity trauma: initial diagnosis and management

Vascular injury associated with extremity trauma occurs in <1% of patients with long bone fracture, although vascular injury may be seen in up to 16% of patients with knee dislocation. In the absence of obvious signs of vascular compromise, limb-threatening injuries are easily missed, with potentially devastating consequences. A thorough vascular assessment is essential; an arterial pressure index <0.90 is indicative of potential vascular compromise. Advances in CT and duplex ultrasonography are sensitive and specific in screening for vascular injury. Communication between the orthopaedic surgeon and the vascular or general trauma surgeon is essential in determining whether to address the vascular lesion or the orthopaedic injury first. Quality evidence regarding the optimal fixation method is scarce. Open vascular repair, such as direct repair with or without arteriorrhaphy, interposition replacement, and bypass graft with an autologous vein or polytetrafluoroethylene, remains the standard of care in managing vascular injury associated with extremity trauma. Although surgical technique affects outcome, results are primarily dependent on early detection of vascular injury followed by immediate treatment.

Fracture consolidation in a tibial nonunion after revascularization: a case report

Poor vascularity can be a potential contributor in the development of fracture nonunion. There is little evidence in orthopaedic literature suggesting that poor vascularity alone may lead to the development of nonunion. Experimental models addressing the effects of ischemia on fracture healing have yielded conflicting views. The case presented here describes a patient who sustained a Type IIIC tibial shaft fracture requiring vascular repair and soft tissue coverage. The patient developed an aseptic, atrophic nonunion. In preparation for operative management of her nonunion, the patient underwent angioplasty in the lower extremity for stenotic vessels. Shortly thereafter, the patient's nonunion went on to unite with no additional intervention, suggesting that revascularization alone resulted in this dramatic progress to union. Further prospective clinical studies may reveal a role for the use of vascular evaluation and intervention in the diagnosis and treatment of nonunion.

Issues in revascularization of the ischemic foot and ankle war injury

The battlefield has provided a multitude of advancements in the management of hemorrhage and vascular repair. Basic understanding of the anatomy and exposures of lower extremity injuries is essential to any surgeon caring for these patients. The techniques of repair and potential adjunctive measures (eg, shunts) available should always be considered when approaching a vascular injury. The most important concept from a vascular standpoint is the fact that a multidisciplinary approach to these complex patients is required with maximal tissue preservation when feasible and safe.

Clinical application of BMP 7 in long bone non-unions

BACKGROUND

Non-unions of long bone fractures are a therapeutic and economic problem of increasing frequency. Aside from conservative treatment options such as ultrasound, impulse waves, and casts, the basic surgical options are autogenous cancellous bone grafting, rod dynamization, reamed nailing, plate fixation, and bone transport techniques. If these methods fail to work, there is a need for alternative treatment options.

METHODS

Since May 2001, treatment with recombinant human bone morphogenic protein 7 (BMP 7 or osteogenic protein 1) in combination with a type-one collagen carrier has been the subject of increasing interest. BMP 7 induces the formation of new bone by stem cell differentiation, thereby initiating the reaction cascade of osteogenesis. Non-unions over 9 months and unsuccessful bone grafting constitute the indication for this treatment.

RESULTS

We report our experience with 54 patients who had atrophic non-union of long bone fractures. Between May 2002 and May 2006, 57 units of BMP 7 were used. The localization of the non-unions included 21 in the femur, 26 in the tibia, 3 in the humerus and 7 in the forearm. In 36 cases, BMP 7 was used in combination with osteosynthesis revision and bone grafting; in 9 additional patients, BMP 7 was used with bone grafting alone. In 12 patients, BMP 7 was applied as a single procedure without any bone grafting or any change in osteosynthesis.

CONCLUSIONS

There were no perioperative or postoperative complications. Follow-up was obtained for a minimum of 6 months. 47 of the 57 (82%) implantations were successful, with bony healing confirmed by clinical and radiological evaluation. In summary, our results support BMP 7 as an additional innovative therapy for long bone non-unions.

Revascularisation during fracture healing with soft tissue injury

INTRODUCTION

The purpose of our study was to quantitatively assess changes in the revascularisation process in the fracture gap and in adjacent regions during the course of healing of diaphyseal fractures with and without closed soft tissue injury.

METHODS

In a rat model (fracture n = 26; fracture with closed soft tissue crush n = 26) revascularisation was assessed in a long-term study with regional mapping by laser Doppler flowmetry, the healing outcome being mechanically tested after 4 weeks. Fracture and soft tissue crush were performed by modified controlled impact device.

RESULTS

No differences in blood circulation were observed at the fracture gap between the study groups up to day 28. In the proximal region of the fracture, the blood circulation in the group with additional soft tissue trauma was down to the baseline throughout the investigation period while the values in the fracture group led to a hyperperfusion after 3 and 7 days. In the distal part at day 1, the blood flow was strongly depressed after fracture, while microcirculation with an additional soft tissue trauma showed only a moderate decline. The reduction of blood circulation in the soft tissue corresponded to the extent of trauma. Mechanical testing demonstrated no significant difference in failure load or in flexural rigidity.

CONCLUSION

Our results indicate that damage severe soft tissue does not adversely affect the fracture healing process. Furthermore, the present findings suggest that a partly destroyed bone-soft tissue interaction resulting in only a temporary and slight reduction of the extraosseous blood supply might have no deteriorating effect on fracture healing outcome. A possible delay in healing is not observed during the first 4 weeks. Therefore, soft tissue damage without destruction of the bone-soft tissue interface is likely to have only a limited effect on fracture healing.

LMP-1 retroviral gene therapy influences osteoblast differentiation and fracture repair: a preliminary study

LIM mineralization protein-1 (LMP-1) is a novel intracellular osteogenic factor associated with bone development that has been implicated in the bone morphogenetic protein (BMP) pathway. This preliminary study evaluated the possibility of LMP-1-based retroviral gene therapy to stimulate osteoblast differentiation in vitro and fracture repair in vivo. A Moloney leukemia virus (MLV)-based retroviral vector to express LMP-1 with a hemagglutinin (HA) tag was developed, and its effects were evaluated on MC3T3-E1 cell differentiation and in the rat femur fracture model. MC3T3-E1 osteoblasts transduced with the MLV-HA-LMP-1 vector demonstrated significantly increased osteoblast marker gene expression (P < 0.05) and mineral deposition compared to control transduced cells. Femoral midshaft fractures were produced in Fischer 344 rats by the three-point bending technique. The MLV-HA-LMP-1 or control vector was applied at the fracture site through percutaneous injections 1 day postfracture. Analysis of fracture healing of 10 MLV-HA-LMP-1-treated and 10 control MLV-beta-galactosidase (beta-gal)-treated animals was completed at 3 weeks by X-ray, peripheral quantitative computed tomography, and histology. MLV-HA-LMP-1-treated animals had 63% more bone mineral content at the fracture site (P < 0.01), 34% greater total hard callus area (P < 0.05), and 45% less cartilage in the fracture callus (P < 0.05) compared to MLV-beta-gal-treated animals. There was no effect of LMP-1 treatment on the density of the hard callus. Immunohistochemistry revealed expression of the LMP-1 transgene in the fracture callus at 21 days postfracture. Immunohistochemistry also revealed that LMP-1 transgene expression did not result in an increase in BMP-4 expression in the fracture callus. Compared to MLV-BMP-4 gene therapy studies, MLV-HA-LMP-1 gene therapy improved bony union of the fracture gap to a greater extent and did not cause heterotopic bone formation. This suggests that LMP-1 may be a better potential candidate for gene therapy for fracture repair than BMP-4. These exciting, albeit preliminary, findings indicate that LMP-1-based gene therapy may potentially be a simple and effective means to enhance fracture repair that warrants further investigation.

[Therapeutic outcome in tibial pseudarthrosis: bone morphogenetic protein 7 (BMP-7) versus autologous bone grafting for tibial fractures]

Depending on the type and localisation, nonunions of tibial fractures will occur in 10-40% of cases. Bone morphogenetic protein 7 (BMP-7; Osigraft), a recombinant bone growth factor, can be implanted locally as an alternative to autologous bone grafting. The objective of our study was to compare the efficiency of the two procedures. From January 1995 to December 2002, 82 patients (group 1) with delayed union of a tibial fracture received autologous bone grafting as their first procedure. To compare their results with the efficiency of BMP-7, between May 2002 and June 2005 we followed up on 26 patients (group 2) who had local implantation of BMP-7 after having had, on average, four surgical procedures. Healing was considered successful if x-rays showed bony consolidation and if no further procedure was necessary. Group 1 had no signs of consolidation in 24 cases (28%), whereas group 2 had only two (8%) such patients (p=0.025). The BMP-7 group showed a significantly higher success rate compared with patients with autologous bone grafting, despite the fact that the BMP-7 group contained more complicated cases.

Inhibition of fracture healing

This paper reviews the current literature concerning the main clinical factors which can impair the healing of fractures and makes recommendations on avoiding or minimising these in order to optimise the outcome for patients. The clinical implications are described.

Vascular abnormalities as assessed with CT angiography in high-energy tibial plafond fractures

OBJECTIVE

The purpose of this study was to examine the results of computed tomography angiography (CTA) obtained in patients with high-energy tibial plafond fractures and assess if the information gleaned from CTA could be useful to the treating orthopedic surgeon.

DESIGN

Consecutive patient series.

SETTING

Level 2 trauma center.

PATIENTS

Consecutive patients treated between October 1, 2004 and June 31, 2006 for high-energy injury of the tibial plafond according to a protocol of early temporizing external fixation, CT, and elevation, followed by delayed reconstruction of the tibial plafond.

INTERVENTION

Addition of angiography to CT scan (CTA) in treatment protocol.

MAIN OUTCOME MEASUREMENTS

CTA abnormalities were identified and categorized to define the pattern of arterial lesions present. Characteristics of patients, injuries, treatments, and complications were evaluated and related to CTA findings.

RESULTS

CTA was performed at an average of 3 days postinjury in 25 consecutive patients treated for high-energy tibial plafond fractures. Abnormalities of the arterial tree of the leg were seen in 13 of 25 (52%) patients. One patient had 2 of 3 vessels notably injured. Fourteen arteries showed acute changes at the level of injury and 1 showed significant chronic atherosclerotic disease at the trifurcation. Acute arterial abnormalities included 7 arteries with complete occlusion, 2 with partial occlusion/diminished flow, and 5 with normal flow but with anatomic disturbances (4 tenting over and 1 entrapped by fracture fragments). Open fractures were associated with arterial abnormalities (P<0.05), but no other characteristics correlated with arterial injury. No patients had dye reactions or other problems relating to CTA. Patients with CTA-diagnosed vascular abnormalities were treated with more minimally invasive surgery than those without at the discretion of the surgeon, and no patients with vascular abnormalities had wound problems or infection.

CONCLUSIONS

In more than half of high-energy tibial plafond fractures, CTA identified significant abnormalities to the arterial tree of the distal leg. These injuries most commonly involved the anterior tibial artery and included a variety of lesions. CTA appears to be a safe and potentially useful tool for the assessment and preoperative planning of high-energy tibial plafond fractures.

Klinische Erfahrungen mit Bone Morphogenetic Protein 7 (BMP 7) bei Pseudarthrosen langer Röhrenknochen

BACKGROUND

Nonunions of long bone fractures are considerable therapeutic and economic problems with increasing tendency. Basic surgical options are autogenous cancellous bone grafting, rod dynamization, reamed nailing, plate fixation with compression, and bone transport techniques. If these methods fail to work, alternative treatment options are needed.

MATERIAL AND METHODS

Since May 2001 treatment with recombinant human (rh) bone morphogenic protein 7 [BMP-7 or osteogenic protein 1 (OP-1)] in combination with a type one collagen carrier has gained interest. BMP 7 induces the formation of new bone by differentiation of stem cells, thereby initiating the reaction cascade of osteogenesis. Nonunions over 9 months and unsuccessful bone grafting delineate the indication.

RESULTS

We report our experience with 21 patients and nonunion of long bone fractures. Between July 2002 and June 2004, 23 units of BMP 7 were implanted. The implantation sites were 7 femora, 12 tibias, 2 humeri, and 2 forearms. In ten cases BMP 7 was combined with a new osteosynthesis and bone grafting and in five patients with bone grafting alone. In contrast in eight patients BMP 7 was applied as a single procedure without any bone grafting or any change of the osteosynthesis.

CONCLUSION

There were no peri- or postoperative complications. Follow-up was obtained for a minimum of 6 months. Of 23 implantations, 22 were successful with bony healing revealed by clinical and radiological evaluation. In one patient no bony consolidation of the nonunion has been seen so far. In summary, based on our results we propose BMP 7 as an additional innovative therapy of long bone nonunions.

Tibial nonunion

Nonunions of the tibia represent challenging orthopedic problems, which require the surgeon to analyze numerous factors and choose an appropriate treatment. Tibial nonunion treatment requires establishing its existence and cause. The treatment algorithm necessitates consideration of a wide variety of factors: the location of the nonunion, the presence or absence of infection, and any angular or rotational deformity. Given advances in implant design and biologic agents, a wide variety of management options exist for the treatment of tibial nonunions. This article reviews surgical treatments for tibial nonunions.

Tibial shaft fractures in children and adolescents

Tibial shaft fractures are among the most common pediatric injuries managed by orthopaedic surgeons. Treatment is individualized based on patient age, concomitant injuries, fracture pattern, associated soft-tissue and neurovascular injury, and surgeon experience. Closed reduction and casting is the mainstay of treatment for diaphyseal tibial fractures. Careful clinical and radiographic follow-up with remanipulation as necessary is effective for most patients. Surgical management options include external fixation, locked intramedullary nail fixation in the older adolescent with closed physis, Kirschner wire fixation, and flexible intramedullary nailing. Union of pediatric diaphyseal tibial fractures occurs in approximately 10 weeks; nonunion occurs in <2% of cases. Some clinicians consider sagittal deformity angulation >10 degrees to be malunion and indicate that 10 degrees of valgus and 5 degrees of varus may not reliably remodel. Compartment syndromes associated with tibial shaft fractures occur less frequently in children and adolescents than in adults. Diagnosis may be difficult in a young child or one with altered mental status. Although the toddler fracture of the tibia is one of the most common in children younger than age 2 years, child abuse must be considered in the young child with an inconsistent history or with suspicious concomitant injuries.

Path analysis of factors for delayed healing and nonunion in 416 operatively treated tibial shaft fractures

A prospective observational study was done in 41 trauma centers. Four hundred sixteen patients with tibial shaft fractures were treated operatively and followed up for at least 6 months. Fifty-two (13%) cases of delayed healing or nonunion were reported. In such nonrandomized observational studies, multiple interrelationships exist between prognostic factors and patient outcomes. We used path analyses to investigate prognostic factors associated with the occurrence of delayed healing or nonunion. The most important factors were identified using multivariate regression analyses, and interrelationships between factors were illustrated using a path diagram. Fractures with open injuries less than and greater than 5 cm were 3.6 and 5.7 times as likely, respectively, to have delayed healing or nonunion as fractures with no skin injuries. The Müller-AO classification of fractures did not provide additional prognostic information. The risk of healing problems was doubled for fractures of the distal shaft and for fractures showing a postoperative diastasis. Treatment options showed an indirect effect on outcome with the occurrence of diastasis. A model for predicting delayed healing or nonunion is proposed. We encourage the use of path analysis in orthopaedics as a powerful visual technique to interpret data from observational studies.

LEVEL OF EVIDENCE

Prognostic study, Level II-1 (retrospective study). See the Guidelines for Authors for a complete description of levels of evidence.

Emergency care in facial trauma--a maxillofacial and ophthalmic perspective

Facial trauma, with or without life- and sight-threatening complications, may arise following isolated injury, or it may be associated with significant injuries elsewhere. Assessment needs to be both systematic and repeated, with the establishment of clearly stated priorities in overall care. Although the American College of Surgeons Advanced Trauma Life Support (ATLS) system of care is generally accepted as the gold standard in trauma care, it has potential pitfalls when managing maxillofacial injuries, which are discussed. Management of facial trauma can arguably be regarded as "facial orthopaedics", as both specialities share common management principles. This review outlines a working approach to the identification and management of life- and sight-threatening conditions following significant facial trauma.