Reamed intramedullary femoral nailing after induction of an "ARDS-like" state in sheep: effect on clinically applicable markers of pulmonary function

Are the unreamed nails indicated in diaphyseal fractures of the lower extremity? A biomechanical study

INTRODUCTION

Intramedullary nailing is generally accepted as the first choice for the treatment of diaphyseal fractures of femur and tibia, with a gradual incease in the use of unreamed nails. Different studies during last years show controversial outcomes. Some authors strongly favor unreamed nailing, but most of the authors conclude that reamed nailing have proved to be more successful.

MATERIAL AND METHODS

This study simulates unreamed intramedullary nailing of four femoral and three tibial fracture types by means of Finite Element (FE) models, at early postoperative stages with a fraction of physiological loads, in order to determine whether sufficient stability is achieved, and if the extent of movements and strains at the fracture site may preclude proper consolidation.

RESULTS

The behavior observed in the different fracture models is very diverse. In the new biomechanical situation, loads are only transmitted through the intramedullary nail. Mean relative displacement values of fractures in the femoral bone range from 0.30 mm to 0.82 mm, depending on the fracture type. Mean relative displacement values of the tibial fractures lie between 0.18 and 0.62 mm, depending on the type of fracture. Concerning mean strains, for femoral fractures the maximum strains ranged between 12.7% and 42.3%. For tibial fractures the maximum strains ranged between 10.9% and 40.8%.

CONCLUSIONS

The results showed that unreamed nailing provides a very limited mechanical stability, taking into account that analyzed fracture patterns correspond to simple fracture without comminution. Therefore, unreamed nailing is not a correct indication in femoral fractures and should be an exceptional indication in open tibial fractures produced by high-energy mechanism.

Healing, nonunion, and re-operation after internal fixation of diaphyseal and distal femoral fractures: a systematic review and meta-analysis

PURPOSE

Nonunion is a highly morbid complication that exacerbates the pain, disability and financial burden of distal and diaphyseal femur fractures. This study examined the modern rates of healing, nonunion, and other complications requiring reoperation of different fixation methods for distal and diaphyseal femur fractures.

METHODS

A systematic review and meta-analysis of all records from PubMed, Embase and the Cochrane Review system was performed. Included studies had >20 acute, non-pathologic distal or diaphyseal femur fractures treated with primary internal fixation. Excluded were studies on abnormal patient/fracture populations, external fixation, or cement/bone graft use.

RESULTS

Thirty-eight studies with 2,829 femoral shaft fractures and 11 studies with 505 distal femur fractures were included. Distal fractures had a lower healing rate (86.6% vs. 93.7%) and a higher re-operation rate (13.4% vs 6.1%) than shaft fractures (p < 0.00001), primarily due to higher rates of mechanical failure (p < 0.00001). Nonunion was the most frequent complication, occurring in 4.7% of distal fractures and 2.8% of shaft fractures. There was no difference between plate and nail fixation of distal fractures in healing, nonunion, or other causes of re-operation. Shaft fractures developed nonunion in 6.6% of unreamed nails and 2.1% of reamed nails (p = 0.002). Nonunion occurred in 2.3% of antegrade nailed fractures and 1.5% of retrograde nailed fractures (p = 0.66).

CONCLUSIONS

Approximately one out of every eight distal fractures and one of every 16 shaft fractures requires re-operation. The most common cause of fixation failure is nonunion. Further research is needed to improve outcomes, particularly in distal femur fractures.

Two variants of fat embolism syndrome evolving in a young patient with multiple fractures

Fat embolism syndrome (FES) is a continuum of fat emboli. Variants of FES: acute fulminant form and classic FES are postulated to represent two different pathomechanisms. Acute fulminant FES occurs during the first 24 h. It is attributed to massive mechanical blockage pulmonary vasculature by the fat emboli. The classic FES typically has a latency period of 24-36 h manifestation of respiratory failure and other signs of fat embolism. Progression of asymptomatic fat embolism with FES frequently represents inadequate treatment of hypovolaemic shock. We present a rare case of two variants of FES evolving in a patient with multiple fractures to emphasis the importance of adequate and appropriate treatment of shock in preventing the development of FES. Since supportive therapy which is a ventilatory support remains as the treatment of FES, it is appropriate to treat FES in the intensive care unit setting.

Second hit phenomenon: existing evidence of clinical implications

The last two decades extensive research evidence has been accumulated regarding the pathophysiology of trauma and the sequelae of interventions that follow. Aim of this analysis has been to collect and categorise the existing data on the so-called "second hit" phenomenon that includes the biochemical and physiologic alterations occurring in patients having surgery after major trauma. Articles were extracted from the PubMed database and the retrieved reports were included in the study only if pre-specified eligibility criteria were fulfilled. Moreover, a constructed questionnaire was utilised for quality assessment of the outcomes. Twenty-six articles were eligible for the final analysis, referring to a total of 8262 patients that underwent surgery after major trauma. Sixteen retrospective clinical studies including 7322 patients and 10 prospective ones, including 940 patients were evaluated. Several variables able to reproduce a post-operative second hit were identified; mostly related to pulmonary dysfunction, coagulopathy, fat or pulmonary embolism, and the inflammatory immune system. Indicative conclusions were extracted, as well as the need for further prospective randomised trials. Suggestions on the content and the rationale of future studies are provided.

Intramedullary nailing as a 'second hit' phenomenon in experimental research: lessons learned and future directions

BACKGROUND

The 'second hit' phenomenon is based on the fundamental concept that sequential insults, which are individually innocuous, can lead to overwhelming physiologic reactions. This response can be expressed in several organic systems and can be examined by measurement of several parameters.

PURPOSES

The purpose of this study was to evaluate the incidence of systemic effects of intramedullary nailing and the role of concurrent head and thoracic injuries as they have been recorded in vivo. We also wanted to determine what would be the optimal animal model for future research and what variables should be investigated.

METHODS

We reviewed the available literature of animal studies that used surgery, and particularly nailing, as a second hit. The reviewed studies were retrieved through an electronic search of the MEDLINE database. We analyzed the methods of creating the first and second hits (nailing), the characteristics of the animal models, the variables examined, and the pathophysiologic responses, which appeared after the second hit.

RESULTS

Second hit reamed intramedullary nailing was found to provoke consumption of coagulation factors, whereas the effect of unreamed nailing on coagulation factors appears inconsistent. Hemodynamic factors were affected only transiently by the second hit, whereas the pulmonary function was affected only when the first hit included lung injury.

CONCLUSIONS

Thoracic and head injuries predispose to an aggravated second hit. Primate animal models are considered to be closer to clinical reality and should be preferred for future studies. Future studies should include measurements of proinflammatory and antiinflammatory markers.

Resuscitation before stabilization of femoral fractures limits acute respiratory distress syndrome in patients with multiple traumatic injuries despite low use of damage control orthopedics

BACKGROUND

Femoral shaft fractures are associated with acute respiratory distress syndrome (ARDS). The idea that primary intramedullary nailing increases the incidence of ARDS has theoretical support. Our approach to treating femoral fractures in patients with multiple traumatic injuries is to perform reamed nailing after adequate resuscitation has been shown by normalizing lactate plus optimized ventilatory and hemodynamic parameters. Damage control orthopedics (DCO) with primary external fixation usually is reserved for those rare patients who do not respond to resuscitation. Our hypothesis was that this approach yields a low rate of ARDS.

METHODS

A prospective trauma database was searched for all femoral shaft fractures treated at a Level I trauma center during a 3-year period, yielding 582 patients. Exclusion criteria included death before treatment (n = 9), age younger than 16 years (n = 16), age older than 65 years (n = 35), fractures that were not amenable to nail fixation (n = 31), shaft fractures treated with a plate (n = 3), patients with bilateral femoral shaft fractures who had a primary nail placed in one femur and an external fixator on the other limb (n = 1), and patients with an Injury Severity Score (ISS) <or=17 (n = 260), leaving 227 patients in the final study group. We defined ARDS as a mean partial pressure of oxygen/fraction of inspired oxygen <200 for 5 or more consecutive days. We compared our results with the results of a similar design in the literature.

RESULTS

Of the 227 patients with ISS >17, only 12% were initially treated with DCO, and 88% were treated with primary reamed nailing. The 227 patients achieved successful early resuscitation as shown by lactate values that decreased significantly on the operative day compared with presenting values (p < 0.05). ARDS rates were low, including rates for the subgroup of patients with lung injury (thoracic Abbreviated Injury Scale score >2, n = 175) who were treated with nailing and had an ARDS rate of 2.0% and a death rate of 2.0%. The ARDS rate for the most severely injured patients who underwent nailing (ISS >28, thoracic Abbreviated Injury Scale score >2, n = 78) was only 3.3%, and 1.7% died.

CONCLUSIONS

In the context of resuscitation before reamed intramedullary nailing of femoral shaft fractures, our rate of ARDS was lower (p < 0.001) than that of a similar study reported in the literature in which the DCO approach was used in up to 36% of patients (p < 0.001) and was more in keeping with previously reported rates of ARDS. This remained true despite frequent use of early reamed femoral nailing and infrequent use of DCO. An explanation for the discrepancy between the centers might be differences in preoperative resuscitation or medical care provided to treat shock.

Fat extravasation due to unreamed and experimentally reamed intramedullary nailing of the sheep femur

AIM

To compare systemic fat extravasation in unreamed and experimentally reamed nailing.

METHODS

An osteotomy was created in the proximal third of the femoral shaft in 16 sheep, and intramedullary pressure increase and fat extravasation were monitored for the two nailing techniques.

RESULTS

The highest intramedullary pressures, median 2700 mm Hg, and highest percentages of fat extravasation, peaking at almost 90% of fat, were found for the unreamed nailing technique. The values for the reamed group were significantly lower.

CONCLUSIONS

The extravasation of intramedullary fat can be attributed to the great increase in intramedullary pressure that occurs during unreamed nailing. Correctly performed intramedullary reaming with the new reaming system produces lower pressures and much less systemic fat extravasation, reducing the risk for fat embolism.

Intramedullary nailing of the femur: current concepts concerning reaming

Intramedullary fixation has advanced to the standard of care for fractures of the femoral shaft. Current controversies center on whether to prepare the intramedullary canal by reaming, particularly in certain subsets of patients. As understanding of the local and systemic effects of reaming deepens, there is a role for maximizing the benefits of intramedullary preparation before nail fixation, while attempting to minimize the major disadvantages of this technique. Several treatment strategies have emerged to address the downsides of intramedullary reaming. The purpose of this review is to discuss the history and current knowledge of intramedullary reaming with respect to problems associated with its use and the evolution of treatment modalities and their clinical applicability for orthopaedic trauma care.

Physical and technical aspects of intramedullary reaming

Intramedullary pressure during reaming is influenced by various factors, including those of the patient, such as bone morphology and location and type of fracture, and those related to reaming technique and instruments. Through intensive research, technical developments and the use of modern materials, intramedullary pressure caused by modern reaming systems can be reduced to a minimum and, perhaps, completely avoided through use of the reaming-irrigation-aspiration system.

Experimental background--review of animal studies

Most of the research on the physiological effects of intramedullary nailing is technically difficult or ethically impossible to perform in humans. A substantial range of factors apply in clinical cases, which means that the data obtained from this source may lack the control needed to reveal the basic mechanisms of pathophysiology associated with this surgical procedure. Consequently, animal studies have been relied upon to provide answers that would otherwise be unavailable. This review manuscript summarizes the available literature on animal studies dealing with the local and systemic effects of intramedullary nailing. It focuses on whether these studies have contributed to our clinical knowledge of the procedure's impact on perfusion and fracture healing, as well as the medical relevance of coincident systemic effects.

DATA SOURCES

Medline, personal library of the first author and of the Department of Trauma Surgery, University of Pittsburgh Medical Center.

STUDY SELECTION

All animal studies on intramedullary stabilization published in English, German, and French.

CONCLUSIONS

The relevance of animal studies investigating the impact of a surgical procedure and its influence on concomitant injuries depends on the design and the type of the animal model. If this fact is considered, and if a model is selected that simulates a systemic impact comparable with the clinical situation, then animal studies may provide a valuable source of otherwise unobtainable information. Such an example is the study of fat embolization associated with intramedullary nailing. Animal subjects enable assessment of the intervention's additive surgical impact, measurement of side effects that may have adverse results, and influence of cofactors (eg, thoracic trauma, severe shock, polytrauma) that predispose the individual to postoperative complications.

Bone marrow fat in the circulation: clinical entities and pathophysiological mechanisms

Fat embolism (FE) and fat embolism syndrome (FES) are controversial topics, particularly regarding their clinical relevance and their independency as a clinical syndrome. FE describes the presence of fat globules within the microcirculation. FES on the other hand, is a clinical syndrome characterized by the presence of FE with the manifestation of an identifiable clinical pattern of signs and symptoms. Both experimental and clinical studies have demonstrated the occurrence and the possible harmful effects of FE. For instance, FE involving the lungs can result in adult respiratory distress syndrome (ARDS). The effects of FE are certainly mechanical, leading to capillary congestion, but are also highly likely to be of a proinflammatory and prothrombotic nature. The demarcation of FES against ARDS is mainly demonstrated by the single organ involvement of ARDS, exclusively influencing the lungs, whereas FES has a multiorgan effect with pulmonary, skin and, neurological manifestations. This article is a review of the pathophysiological mechanisms of FE and the clinical occurrence and influence of FE and FES.

Fat embolism: the reaming controversy

Intramedullary nailing is the preferred treatment method for stabilizing femoral diaphyseal fractures. Despite its superior biomechanical advantages over other implants, its use, particularly in selected groups of patients, has been questioned because of the possible harmful systemic effects of intramedullary reaming. The increase in intramedullary canal pressure during intramedullary nailing can result in intravasation of bone marrow and fat into the venous blood system. The subsequent consequences can be fat embolism syndrome (FES), adult respiratory distress syndrome (ARDS), and multiple organ failure. The lung seems to be the primary target for fat embolization and for the mediated effects primed by inflammatory reactions. In laboratory studies, both reamed and unreamed intramedullary nailing has been shown to alter selected pulmonary variables. Although transient, this effect appears to be more prominent with reamed than unreamed techniques. Additional studies are required to determine whether a subgroup of trauma patients is adversely affected by intramedullary reaming, thus necessitating other fixation techniques.

Evolving trends in the care of polytrauma patients

Management of polytrauma patients has changed considerably in recent years. This is in keeping with the developments that have occurred in the fields of fracture fixation techniques and intensive care. Prior to the 1970s, patients with multiple injuries were treated non-operatively, as it was believed that they were too ill to withstand surgery. Around this time, literature appeared to suggest that these patients had high rates of complications as a result of prolonged recumbency. Fracture fixation techniques were also developing rapidly, and these events led to the advent of early fracture stabilisation of multiply injured patients, known as early total care. In the following decade, the surgical world came to recognise that early stabilisation of skeletal injuries produced poor results in certain patients. The concept of 'damage control' surgery was introduced for multiply injured patients. The current era may give way to new methods as our understanding of the pathophysiology of polytrauma improves.

Pulmonary aspects of treatment of long bone fractures in the polytrauma patient

During the past decade, there have been significant advances in the treatment of long bone fractures in the polytraumatized patient. The major controversy in this area is whether definitive long bone stabilization needs to be done emergently. In general, definitive fixation should be done early in the patient's hospital course after it is determined that the patient is hemodynamically stable and is resuscitated adequately. The major benefits of fixation are: (1). improve mobilization to enhance pulmonary function; (2). decreased narcotic requirements with improved pain control after fixation; and (3). early aggressive fluid resuscitation associated with operative intervention. Patients with multisystem injury who are underresuscitated or are unstable should have early external fixation because temporizing skeletal stabilization until definitive fixation can be done.

Intramedullary nailing of multiple long-bone fractures of the lower extremity at the same surgery: a single-center experience

We evaluated the outcome of multiple intramedullary nailing at the same surgery for traumatic long-bone fractures. All but 2 of 27 patients (average age 40) had been involved in motor vehicle accidents, and 17 of them presented with other associated nonorthopedic injuries. Ten patients had open fractures. Sixty-one nails were used. The average time from accident to fixation was 8.16 h, and the average time in the operating room was 5.4 h. No patients died; all required blood transfusion; and eight patients were admitted for at least 24 h to the intensive care unit. The average hospital stay was 27 days, the mean time to full weight-bearing was 4 months, and the average time to radiographic healing was 7.5 months. Three patients required dynamization to achieve fracture union; three underwent exchange nailing for nonunion and one for nail breakage. Thus, early fixation of multiple long-bone fractures by intramedullary nailing in polytrauma patients is an acceptable treatment method.

Bone formation following intramedullary femoral reaming is decreased by indomethacin and antibodies to insulin-like growth factors

OBJECTIVE

We aimed to: 1). compare rates of in vitro bone formation following reamed and nonreamed intramedullary fixation in a murine model of femoral fracture healing; and 2). examine whether antibodies to insulin-like growth factor (IGF) I, IGF II, or indomethacin (an inhibitor of the inflammatory process) affect bone formation following intramedullary reaming.

DESIGN

Experimental study.

PARTICIPANTS

Twenty-four C57 black mice were randomized to two groups: reamed ( = 12), and nonreamed intramedullary nail insertion ( = 12).

INTERVENTION

In the reamed group, the femoral canals were successively reamed with 30-, 27-, 25-, and 23-gauge stainless steel pins and stabilized with a 27-gauge pin. In mice randomized to the nonreamed group, a 27-gauge pin was inserted. An external three-point bending force created a midshaft transverse femoral fracture. Seven days postsurgery, each mouse was killed, and the right femur was removed. Following pin removal, the callus was minced, the bone marrow was removed, and both were ultracentrifuged at 1200 rpm for 5 minutes. The supernatent was cocultured with 3-day-old murine calvarial cells in culture media. At day 5 of culture, reamed plasma and calvarial cell cocultures were exposed to either 1.0 micro g/mL of anti-IGF I, 1.0 micro g/mL of anti-IGF II, 2 micro M indomethacin, or served as controls (calvarial cells only). The cells were cultured for a total of 21 days.

MAIN OUTCOME MEASUREMENTS

The number of bone nodules was quantified by light microscopy.

RESULTS

Reamed pin insertion resulted in 4.1-fold and 8.9-fold increases in the mean number of bone nodules compared to pins inserted without reaming and controls, respectively (399 +/- 40.0 vs. 97.0 +/- 21.0, < 0.001). The positive effect of intramedullary reaming on bone nodule formation was reversed with the administration of antibodies to IGF I and IGF II. The addition of anti-IGF I or anti-IGF II to calvarial, or osteoblastlike, cells treated with supernatent from the callus and bone marrow of mice with prior intramedullary reaming resulted in significant declines in the mean number of bone nodules ( < 0.001). Specifically, treatment of osteoblastlike cells with anti-IGF I or anti-IGF II resulted in 7.0-fold and 5.4-fold declines in mean bone nodule formation compared to cells without such treatment.

CONCLUSIONS

Intramedullary reaming prior to pin insertion resulted in a significantly greater number of bone nodules than pin insertion only. Antibodies to IGF I, IGF II, and indomethacin reversed the stimulatory effect of reaming on bone nodule formation, suggesting their role in modulating the course of fracture healing following intramedullary reaming.

Effects of intramedullary femoral fracture fixation: what is the impact of experimental studies in regards to the clinical knowledge?

This review manuscript summarizes the available literature on animal studies dealing with the local and systemic effects of intramedullary (IM) reamed and unreamed nailing. It focuses on the question of whether the large numbers of studies have contributed to our clinical knowledge about its impact on perfusion, fracture healing, and about the clinical relevance of systemic side effects. The effects of IM contents that are squeezed out of the medullary canal into the venous and the systemic circulation due to reaming and nailing has been a major issue. In addition, the impact of the surgical procedure and the timing of such a major operation as femoral fractures surgery has been a major source of debate within the last decade. The compilation of relevant studies investigating the degree of impact of a surgical procedure and the influence of concomitant injuries depends on the design and the type of the animal model. If this fact is considered and if a model is selected that reflects the systemic impact comparable with the clinical situation, animal studies represent a valuable source of information. In this respect, fat embolization represents an additive surgical impact and can cause clinically relevant side effects if cofactors (e.g., thoracic trauma, severe shock, and polytrauma) are present that set the individual up for postoperative complications.

Fat embolism and related effects during reamed and unreamed intramedullary nailing in a pig model

OBJECTIVES

To determine whether reamed or unreamed femoral intramedullary nailing is more adverse to pulmonary function, the authors compared three populations of healthy pigs, analyzing the biochemical and hemodynamic effects related to fat embolism. Likewise, the authors histologically evaluated the presence of bone marrow fat embolism in lungs, heart, kidney, brain, and retina.

DESIGN

Randomized, experimental model.

SETTING

Laboratory.

PARTICIPANTS

Twenty-five male Duroc Jersey adult healthy pigs divided in three groups.

INTERVENTION

Reamed and unreamed intramedullary nailing.

OUTCOME MEASUREMENTS

Biochemical, hemodinamical, and histologic analysis.

METHODS

In the first group of ten pigs, a reamed nail was inserted; in the second group of ten specimens, the authors placed an unreamed nail; and in the third group of five animals (control), only the surgical approach was made without opening the medullary cavity.

RESULTS

The authors did not find statistically significant differences in pulmonary function between the reamed and unreamed group in the hemodynamic, biochemical, and histopathologic parameters evaluated. The histologic analysis of the lung tissue revealed a statistically significant difference between the nailed groups and the control (P < 0.04).

CONCLUSIONS

In this animal model, the results indicate that pulmonary changes and fat embolization during intramedullary nailing occur to the same degree in reamed and in unreamed femurs.

How risky is early intramedullary nailing of femoral fractures in polytraumatized patients?

There is controversy over both the time of intervention and the technique of surgical stabilisation of femoral fractures in polytraumatized patients. Retrospective analysis of data on 55 such patients revealed that stabilisation within the first 24 h using locked, unreamed nails had no negative impact on the rate of pulmonary complications. The frequency of complications was assessed by comparing immediate intramedullary (IM) osteosynthesis with extramedullary stabilisation in patients with or without concomitant blunt thoracic trauma. Due to the small study population and discrepancies the size of subgroups, no definite statistical conclusions were possible. However, our results suggest that the frequency of complications is determined by the overall severity of injury rather than by the type of acute surgical treatment.

Intramedullary nailing of the femur: reamed versus nonreamed

All intramedullary nailing creates some loss of endosteal blood supply and an increase in intramedullary pressure, resulting in marrow embolization. In laboratory studies, both reamed and nonreamed intramedullary nailing have led to alteration in selected pulmonary variables. This effect, although transient, appeared more pronounced with reamed techniques than with nonreamed techniques. Concern about the systemic pulmonary effects of reamed intramedullary nailing has led to an increase in the use of nonreamed nailing. The authors of most clinical studies have reported that reamed intramedullary nailing has not been associated with a concomitant increase in pulmonary complications in multiply injured patients, although this point is still controversial. Femoral shaft fractures treated with nonreamed nailing have been shown to have slightly higher rates of delayed union and nonunion compared with those treated with reamed nails. Reamed interlocking intramedullary fixation remains the treatment of choice for femoral shaft fractures in adults. Further study is required to determine whether an identifiable subgroup of trauma patients is adversely affected by intramedullary reaming, which would suggest the need for alternative fixation techniques.