Effects on pulmonary physiology of reamed femoral intramedullary nailing in an open-chest sheep model

Quantitative Evaluation of Embolic Load in Femoral and Tibial Shaft Fractures Treated With Reamed Intramedullary Fixation

OBJECTIVES

To compare the volume of embolic load during intramedullary fixation of femoral and tibial shaft fractures. Our hypothesis was that tibial intramedullary nails (IMNs) would be associated with less volume of intravasation of marrow than IM nailing of femur fractures.

DESIGN

Prospective observational study.

SETTING

Urban Level I trauma center.

PATIENTS/PARTICIPANTS

Twenty-three patients consented for the study: 14 with femoral shaft fractures and 9 with tibial shaft fractures.

INTERVENTION

All patients underwent continuous transesophageal echocardiography, and volume of embolic load was evaluated during 5 distinct stages: postinduction, initial guide wire, reaming (REAM), nail insertion, and postoperative.

MAIN OUTCOME MEASUREMENTS

Volume of embolic load was measured based on previously described luminosity scores. The embolic load based on fracture location and procedure stage was evaluated using a mixed effects model.

RESULTS

The IMN procedure increased the embolic load by 215% (-12% to 442%, P = 0.07) in femur patients relative to tibia patients after adjusting for baseline levels. Of the 5 steps measured, REAM was associated with the greatest increase in embolic load relative to the guide wire placement and controlling for fracture location (421%, 95% confidence interval: 169%-673%, P < 0.01).

CONCLUSIONS

Femoral shaft IMN fixation was associated with a 215% increase in embolic load in comparison with tibial shaft IMN fixation, with the greatest quantitative load during the REAM stage; however, both procedures produce embolic load.

LEVEL OF EVIDENCE

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

Does Intramedullary Nail Fixation of the Tibia Pose the Same Risk of Pulmonary Complications as Intramedullary Nail Fixation of the Femur? A Propensity Score-Matched Analysis

OBJECTIVES

To compare duration of mechanical ventilation and pulmonary outcomes in patients treated with intramedullary nail (IMN) fixation of the tibia versus the femur.

DESIGN

Retrospective cohort study.

SETTING

Level I trauma center.

PATIENTS

One thousand thirty patients were categorized based on treatment: those treated with IMN of the tibia (n = 515) and those treated with IMN of the femur (n = 515).

INTERVENTION

IMN fixation of tibial and femoral fractures.

OUTCOME MEASUREMENTS

The primary outcome was duration of mechanical ventilation. Secondary outcomes included length of intensive care unit (ICU) stay and risk of tracheostomy, pulmonary embolism (PE), acute respiratory distress syndrome (ARDS), and mortality.

RESULTS

In an unadjusted analysis, femoral fractures were associated with increase in ventilator days (mean difference, 1.4; P < 0.001), ICU days (mean difference, 1.8; P < 0.001), and odds of tracheostomy (odds ratio, 1.7; P < 0.01). No difference was shown in likelihood of PE, ARDS, or mortality (P > 0.2). Propensity score-matched estimates showed no differences in any measured outcomes (P > 0.40). In patients with Injury Severity Scores >17, we found no difference in length of ventilator or ICU days or likelihood of tracheostomy, PE, ARDS, or mortality in the unadjusted (P > 0.2) or propensity score-matched estimates (P > 0.3).

CONCLUSIONS

These findings suggest that IMN fixation of the tibia is associated with duration of mechanical ventilation and risk of poor pulmonary outcomes similar to those of femoral nailing, after adjustment for baseline characteristics.

LEVEL OF EVIDENCE

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

Non-osteotomy and osteotomy large animal fracture models in orthopedic trauma research

Large animal fracture models are important in the field of orthopedic trauma research. New implants are tested in animals before being implanted into humans. Large animals like sheep or swine often are more properly to simulate conditions in humans, e.g. biomechanical demands, compared to rodents. Cited articles mainly analyze shock or fracture healing. Both osteotomy and non-osteotomy fracture models have been used in the past. However, comparative studies are rare and clear recommendation when to use which model are missing. This review will summarize large animal fracture models putting special emphasis on non-osteotomy fracture models.

Prediction of pulmonary morbidity and mortality in patients with femur fracture

BACKGROUND

We aimed to determine the effect of femur fractures on mortality, pulmonary complications, and adult respiratory distress syndrome (ARDS). In addition, we aimed to compare the effect of femur fractures with other major musculoskeletal injuries and to determine the effect of timing to surgery on these complications.

METHODS

All patients were identified from the trauma registries of two Level I trauma centers. Outcomes were defined at mortality in hospital, pulmonary complications, and ARDS in hospital. Regression analysis was used to determine the effect of femur fractures, while controlling for age, Abbreviated Injury Scales, Glasgow Coma Scale, and systolic blood pressure at presentation. We compared femur fractures with other major musculoskeletal injuries in similar models. Within the patients with femur fracture, time to surgery (< 8 hours, 8 hours to 24 hours, and > 24 hours) was evaluated using similar regression analysis.

RESULTS

Of the total 90,510 patients, 3,938 (4.35%) died in the hospital, 2,055 (2.27%) had a pulmonary complication, and 285 (0.31%) developed ARDS. Femur fracture is statistically predictive of mortality (odds ratio [OR], 1.606; 95% confidence interval [CI], 1.288-2.002) and pulmonary complications (OR, 1.659; 95% CI, 1.329-2.070), when controlling for other injury factors. This was comparable with the effect of pelvic fracture and other major musculoskeletal injuries. Femur fracture had a strong relationship with ARDS (OR, 2.129; 95% CI, 1.382-3.278). Patients treated in the 8 hours to 24 hours window had the lowest mortality risk (OR, 0.140; 95% CI, 0.052-0.375), and there was a trend to increased risk of ARDS in a delay to surgery of > 24 hours.

CONCLUSIONS

Femur fractures are a major musculoskeletal injury and increase the risk of mortality and pulmonary complications as much as any other musculoskeletal injuries. There is a unique relationship between ARDS and femur fractures, and this must be considered carefully in treatment planning for these patients.

A cadaver model evaluating femoral intramedullary reaming: a comparison between new reamer design (Pressure Sentinel) and a novel suction/irrigation reamer (RIA)

OBJECTIVE

To compare the intramedullary pressures developed during reaming of cadaveric femurs with the Synthes Reamer/Irrigator/Aspirator (RIA) reamer and the Zimmer Pressure Sentinel (PS) reamer, controlling for the force and speed of reaming.

METHOD

Fifteen matched pairs of frozen unpreserved femurs were used in the study. Two pressure transducers and two thermocouples were screwed into holes drilled into the femoral shaft. The femurs were stabilized in the vertical position by mechanically attaching them to a custom jig equipped with a load cell to detect the vertical component of force applied to the reamer. Proximally a linear voltage displacement transducer (LVDT) was attached to the reamer to record the continuous position of the reamer. All femurs were reamed to a diameter 2 mm larger than the narrowest point of the canal. Proximal and distal pressures, proximal and distal temperatures, applied vertical force and displacement were measured continuously throughout the reaming process. Maximum and minimum, and average proximal and distal pressures for each reamer were obtained and compared using paired t-tests. Averages were also calculated and compared in the same manner. A p-value of <0.05 was considered statistically significant.

RESULTS

The maximum, minimum and average intramedullary pressures during reaming were significantly lower with the RIA system than the PS reamer. In general, the pressures produced by the RIA system were consistently below atmospheric pressure for the majority of the reaming time. This was not true for the PS system. No appreciable temperature changes were observed during any of the trials.

CONCLUSION

The RIA reaming system significantly reduces the intramedullary pressures produced during the reaming process compared to the PS reaming system.

Reaming does not add significant time to intramedullary nailing of diaphyseal fractures of the tibia and femur

BACKGROUND

Reamed intramedullary nailing is the current gold standard for the treatment of diaphyseal fractures of the femur and tibia. Current concepts of orthopedic damage control surgery for patients with multiple injuries have placed an emphasis on appropriate surgical timing, limiting blood loss, and the duration of the initial operative procedure(s). Proponents of unreamed nailing have stated that reaming places polytraumatized patients "at risk," in part because it adds to the length of the surgical procedure and may exacerbate the severity of a patient's pulmonary injury. The purpose of this study was to determine how many minutes reaming actually takes and what percentage of operative time reaming comprises during intramedullary nailing of femoral and tibial shaft fractures.

METHODS

Intraoperative timing data were collected prospectively on a total of 52 patients with 54 fractures (21 femoral and 33 tibial) who underwent reamed intramedullary nailing of acute closed or open femoral or tibial shaft fractures over a 10-month period. Total operating room, surgical, and reaming times were collected.

RESULTS

The average reaming time for femur and tibia fractures was 6.9 minutes and 7 minutes, respectively. On average, reaming accounted for 4.9% of the surgical time and 3.2% of the total operating room time for femur fractures and 4.9% of the surgical time and 3.4% of the total operating room for tibia fractures.

CONCLUSION

Our results show that reaming comprises a small percentage of the operative time and the total time a patient spends in the operating room.

Delayed internal fixation of femoral shaft fracture reduces mortality among patients with multisystem trauma

BACKGROUND

Fractures of the femoral shaft are common and have potentially serious consequences in patients with multiple injuries. The appropriate timing of fracture repair is controversial. The purpose of the present study was to assess the effect of timing of internal fixation on mortality in patients with multisystem trauma.

METHODS

We performed a retrospective cohort study with use of data from public and private trauma centers throughout the United States that were reported to the National Trauma Data Bank (version 5.0 for 2000 through 2004). The study included 3069 patients with multisystem trauma (Injury Severity Score, > or =15) who underwent internal fixation of a femoral shaft fracture. The time to treatment was defined in categories as the time from admission to internal fixation: t(0) (twelve hours or less), t(1) (more than twelve hours to twenty-four hours), t(2) (more than twenty-four hours to forty-eight hours), t(3) (more than forty-eight hours to 120 hours), and t(4) (more than 120 hours). The relative risk of in-hospital mortality when the four later periods were compared with the earliest one was estimated with inverse probability of treatment-weighted analysis. Subgroups with serious head or neck, chest, abdominal, and additional extremity injury were investigated.

RESULTS

When compared with that during the first twelve hours after admission, the estimated mortality risk was significantly lower in three time categories: t(1) (relative risk, 0.45; 95% confidence interval, 0.15 to 0.98; p = 0.03), t(3) (relative risk, 0.58; 95% confidence interval, 0.28 to 0.93; p = 0.03), and t(4) (relative risk, 0.43; 95% confidence interval, 0.10 to 0.94; p = 0.03). Patients with serious abdominal trauma (Abbreviated Injury Score, > or =3) experienced the greatest benefit from a delay of internal fixation beyond twelve hours (relative risk, 0.82 [95% confidence interval, 0.54 to 1.35] for patients with an Abbreviated Injury Score of <3, compared with 0.36 [95% confidence interval, 0.13 to 0.87] for those with an Abbreviated Injury Score of > or =3) (p value for effect modification, 0.09).

CONCLUSIONS

Delayed repair of femoral shaft fracture beyond twelve hours in patients with multisystem trauma, which may allow time for appropriate resuscitation, reduces mortality by approximately 50%. Patients with serious abdominal injury benefit most from delayed treatment. These results support delaying definitive treatment of long-bone injuries in patients with multisystem trauma as a means of so-called damage-control in order to reduce adverse outcomes.

Intramedullary nailing of the lower extremity: biomechanics and biology

The intramedullary nail or rod is commonly used for long-bone fracture fixation and has become the standard treatment of most long-bone diaphyseal and selected metaphyseal fractures. To best understand use of the intramedullary nail, a general knowledge of nail biomechanics and biology is helpful. These implants are introduced into the bone remote to the fracture site and share compressive, bending, and torsional loads with the surrounding osseous structures. Intramedullary nails function as internal splints that allow for secondary fracture healing. Like other metallic fracture fixation implants, a nail is subject to fatigue and can eventually break if bone healing does not occur. Intrinsic characteristics that affect nail biomechanics include its material properties, cross-sectional shape, anterior bow, and diameter. Extrinsic factors, such as reaming of the medullary canal, fracture stability (comminution), and the use and location of locking bolts also affect fixation biomechanics. Although reaming and the insertion of intramedullary nails can have early deleterious effects on endosteal and cortical blood flow, canal reaming appears to have several positive effects on the fracture site, such as increasing extraosseous circulation, which is important for bone healing.

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.

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.

Use of veterinary interlocking nails for diaphyseal fractures in dogs and cats: 121 cases

OBJECTIVE

To report clinical outcome after use of an interlocking nail (veterinary interlocking nail [VIN]) for stabilization of diaphyseal fractures in dogs and cats.

STUDY DESIGN

Retrospective study.

ANIMALS

Seventy-eight dogs and 43 cats with diaphyseal fractures of the femur (n = 96), tibia (n = 14), or humerus (n = 11).

METHODS

Interlocking nails (4 mm diameter [n = 72], 6 mm [n = 25] or 8 mm [n = 24]), were used in static (n = 106) or dynamic (n = 15) fixation mode. Cerclage wires also were used in 63 (52%) cases. Data about the patient (species, breed, weight, age), characteristics of the fracture, and details of the surgery and perioperative complications were recorded. The surgeon evaluated functional outcome, and fracture healing was quantified 6 weeks (W6) and 3 months (M3) after surgery with a radiographic index.

RESULTS

Twelve cases had been unsuccessfully treated by another technique. Of 106 comminuted fractures, 60 were classified as unstable. Only 112 animals were evaluated at W6; 86 (77%) healed without complication and had a functional outcome considered excellent (n = 80, 93%), good (n = 5, 4%), or fair (n = 1). Twenty-six complications were noted: 16 (14%) patients did not require additional surgery and had a good or excellent outcome, whereas 10 (8%) patients needed surgical intervention to

CONCLUSIONS

VINs can be used to repair diaphyseal fractures of the femur, tibia, and humerus in dogs and cats provided the implants are appropriately sized for the fractured bone. The high healing rate (even with unstable fractures), associated with a functional outcome, and low complication rate support the use of VINs for these fracture types. However, a period of training and the application of basic principles are necessary to ensure successful results.

CLINICAL RELEVANCE

VINs should be considered as alternative technique for management of selected diaphyseal fractures of the femur, tibia, and humerus in dogs and cats.

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.

Timing of femur fracture fixation: effect on outcome in patients with thoracic and head injuries

BACKGROUND

Optimal timing of femur fracture fixation remains controversial. This study examines the association between the timing of femur fracture fixation and outcome in patients with concomitant chest and head injuries.

METHODS

A retrospective review of registry data from a Level I trauma center identified 1362 patients with a femoral shaft fracture over a 12-year period. Patients were categorized into five groups by timing of femur fracture fixation: Group 1, within 24 hours; Group 2, 24 to 48 hours; Group 3, 48 to 120 hours; Group 4, > 120 hours; and Group 5, patients with no operative fixation. Primary outcome measures included morbidity (specifically, pulmonary complications) and mortality. Secondary outcome measures were hospital length of stay, intensive care unit length of stay, and discharge Glasgow Coma Scale score. Subsets of patients were examined including all patients with multiple injuries (Injury Severity Score > 15), chest trauma (Chest Abbreviated Injury Scale score > or = 2), and head trauma (Head Abbreviated Injury Scale score > or = 2).

RESULTS

Acute respiratory distress syndrome, pneumonia, hospital length of stay, and intensive care unit length of stay were lowest in the group fixed within 24 hours, even in patients with concomitant head or chest trauma. Fixation between 2 and 5 days was associated with a significantly increased incidence of acute respiratory distress syndrome, pneumonia, and fat embolization syndrome in patients with concurrent chest trauma (p < 0.0001). In head-injured patients, discharge Glasgow Coma Scale score was highest in the group fixed within 24 hours. Timing of operative fixation did not affect mortality.

CONCLUSION

Our data show that early femur fracture fixation (< 24 hours) is associated with an improved outcome, even in patients with coexistent head and/or chest trauma. Fixation of femur fractures at 2 to 5 days was associated with a significant increase in pulmonary complications, particularly with concomitant head or chest trauma, and length of stay. Chest and head trauma are not contraindications to early fixation with reamed intramedullary nailing.

Healing of closed femoral shaft fractures treated with the AO unreamed femoral nail. A comparative study with the AO reamed femoral nail

Out of a hundred and seven closed femoral fractures, fifty-three were treated with the unreamed femoral nail and fifty-four with the reamed femoral nail. There were four delayed unions in the Unreamed Femoral Nail group (UFN) and three in the Reamed Femoral Nail group (RFN). There were no cases of infection or malunion. Implant failure was the cause of implant conversion in one patient of the UFN group. Healing time of the femoral fractures was 19.2 weeks in the UFN group and 19.6 weeks in the RFN group. Due to the significant decrease in operating time with the UFN (70 min) in comparison with the RFN (125 min) and the possible risk of posttraumatic pulmonary oedema (ARDS) with reaming techniques, the authors recommend the UFN for the treatment of acute closed femoral shaft fractures.

The effect of reamed and nonreamed intramedullary nailing on fracture healing

Intramedullary nailing has revolutionized the treatment of fractures. It is important to be aware of the biological and mechanical effects of reaming and nailing on bone. Most nails are substantially stiffer than bone, but because of their location in the medullary canal do not have nearly as adverse an effect on callus strength as plates. Reaming and nailing embolizes marrow contents into the systemic circulation and reduces blood flow to the total bone and cortex by 30% to 80%. This results in a hyperemic reaction that revascularizes the cortex depending on the type of nail used. Preservation of the soft tissue envelope around the fracture enhances this response resulting in fracture healing ratio of 98% when closed nailing techniques are used. The primary advantage of nonreamed nailing is better preservation of the blood supply to the cortex whereas the major advantage of reamed nailing is a more rigid construction, stronger implants, and earlier fracture union.

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

OBJECTIVES/HYPOTHESIS

At present, the optimal treatment for appropriately resuscitated, multiply injured patients includes fixation of long bone fractures within twenty-four hours of injury. This management approach has been shown to decrease the incidence of pulmonary complications, multiple organ failure, and death. Some investigators have hypothesized that acute reamed intramedullary nailing of the femur (RIMNF) may result in pulmonary dysfunction as a result of the pulmonary fat embolization generated during this procedure. Patients with concomitant thoracic trauma may be at particular risk for this potentially severe complication. In an attempt to determine whether RIMNF can be safely carried out regardless of the severity of a pulmonary injury, we monitored the pulmonary effects of RIMNF in sheep in which an acute respiratory disorder (ARDS)-like state had been induced. Our hypothesis was that, if the pulmonary fat embolization that occurs as a result of RIMNF has a clinically significant effect, it would be detectable in an animal model in which a severe lung injury had been induced prior to the start of RIMNF.

STUDY DESIGN

This was an acute experimental procedure performed on yearling sheep.

METHODS

Reamed intramedullary nailing of the femur was performed in two groups of instrumented sheep. The first group had no pulmonary injuries. The second group had an ARDS-like state induced by intravenous infusion of perilla ketone prior to RIMNF. Perilla ketone increases pulmonary microvascular permeability without changing filling pressures and is used to induce a model of human ARDS. Hemodynamic and oximetric parameters were measured or calculated, as was pulmonary dynamic compliance during the experiment.

RESULTS

Infusion of perilla ketone caused a significant pulmonary injury. RIMNF caused no additional significant effect on intrapulmonary shunt, mixed venous oxygen saturation, or dynamic compliance, which are clinically used to assess the severity of pulmonary dysfunction in injured patients.

CONCLUSIONS

The fat embolization that occurs during RIMNF in an appropriately resuscitated sheep has no clinically significant effect on pulmonary function, even in the setting of a severe pulmonary dysfunction.

Thoracic trauma and early intramedullary nailing of femur fractures: are we doing harm?

INTRODUCTION

It has been reported that early intramedullary nailing (IMN) of a femur fracture in the presence of thoracic injury increases morbidity and mortality. The purpose of the present study was to determine if IMN < or = 24 hours after multisystem injury (Injury Severity Score (ISS) > 16) is associated with a poor hospital outcome in the presence of blunt thoracic trauma (Abbreviated Injury Scale (AIS) thorax score > or = 2).

METHODS

Retrospective cohort study at a single adult trauma center.

RESULTS

In a 6-year period, 149 blunt trauma patients had both an ISS > 16 and a femur fracture managed by IMN. These 149 patients were divided into four groups based on thoracic injury (T = AIS thorax score > or = 2; N = AIS thorax score < 2) and the timing of IMN (E = < or = 24 hours; L = > 24 hours). There were 68 TE, 57 NE, 15 TL, and 9 NL patients. The TE and NE groups were similar in age and ISS. TE and NE groups had similar durations of ventilation, critical care, hospital stay, and mortality. Furthermore, TE patients were no more likely to be intubated after IMN than NE patients. TE patients were matched with similar patients without a femur fracture and found to have similar hospital outcomes.

CONCLUSIONS

This study has not demonstrated an increased morbidity or mortality associated with early IMN in the presence of thoracic trauma.