Fat embolus in femur fractures: a comparison of two reaming systems.

OBJECTIVE: To measure the amount of fat presented to the right heart during reaming and nail placement using two different reamer systems. DESIGN: Prospective, randomized clinical trial. SETTING: University-based Level I Trauma Center. PATIENTS: 20 patients with femur fractures. INTERVENTION: Patients with femur fractures were treated with intramedullary nailing using either reamer-irrigator-aspirator or a conventional reamer. MAIN OUTCOME MEASURE: four-chamber trans-esophageal echocardiogram was used to quantify the amount of fat presented to the right atrium. RESULTS: There were 2 female and 18 male patients enrolled, 10 in each group. There was no significant difference (p = 0.10) between reaming systems on the opening reamer, which was expected since both trial limbs used the same opening reamer. However, during the first pass of the reamer, the RIA showed a nearly-significant decrease in the volume of fat in the right atrium (p = 0.06). During passage of the nail, there was a significant difference with Group B having less fat embolus than Group A (p = 0.01). The power of this study is 0.81. The mean ISS was not significantly different between the two groups, nor was the sex, age or race. There was one death from cardiac complications in a patient who showed no fat during any phase of the procedure. This patient had significant mitral and aortic regurgitation pre-operatively. There was one patient with clinical fat embolism syndrome and one patient with a nonunion. CONCLUSIONS: There is a statistically significant difference in the amount of fat presented to the lungs using a RIA versus conventional reamer.

Negative pressure wound therapy after severe open fractures: a prospective randomized study.

OBJECTIVES: To evaluate the impact of negative pressure wound therapy (NPWT) after severe open fractures on deep infection. DESIGN: Prospective randomized study. SETTING: Academic level I trauma center. PATIENTS/PARTICIPANTS: Fifty-nine patients with 63 severe high-energy open fractures were enrolled in this study, with data available on 58 patients with 62 open fractures. INTERVENTION: Twenty-three patients with 25 fractures randomized to the control group and underwent initial irrigation and debridement followed by standard fine mesh gauze dressing, with repeat irrigation and debridement every 48-72 hours until wound closure. Thirty-five patients randomized to the NPWT group and had identical treatment except that NPWT was applied to the wounds between irrigation and debridement procedures until closure. MAIN OUTCOME MEASUREMENTS: The presence or absence of deep wound infection or osteomyelitis, wound dehiscence, and fracture union were primary outcome measures. RESULTS AND CONCLUSIONS: Control patients developed 2 acute infections (8%) and 5 delayed infections (20%), for a total of 7 deep infections (28%), whereas NPWT patients developed 0 acute infections, 2 delayed infections (5.4%), for a total of 2 deep infections (5.4%). There is a significant difference between the groups for total infections (P = 0.024). The relative risk ratio is 0.199 (95% confidence interval: 0.045-0.874), suggesting that patients treated with NPWT were only one-fifth as likely to have an infection compared with patients randomized to the control group. NPWT represents a promising new therapy for severe open fractures after high-energy trauma.

Biomechanical response of the pubic symphysis in lateral pelvic impacts: a finite element study.

Automotive side impacts are a leading cause of injuries to the pubic symphysis, yet the mechanisms of those injuries have not been clearly established. Previous mechanical testing of isolated symphyses revealed increased joint laxity following drop tower lateral impacts to isolated pelvic bone structures, which suggested that the joints were damaged by excessive stresses and/or deformations during the impact tests. In the present study, a finite element (FE) model of a female pelvis including a previously validated symphysis sub-model was developed from computed tomography data. The full pelvis model was validated against measured force-time impact responses from drop tower experiments and then used to study the biomechanical response of the symphysis during the experimental impacts. The FE models predicted that the joint underwent a combination of lateral compression, posterior bending, anterior/posterior and superior/inferior shear that exceeded normal physiological levels prior to the onset of bony fractures. Large strains occurred concurrently within the pubic ligaments. Removal of the contralateral constraints to better approximate the boundary conditions of a seated motor vehicle occupant reduced cortical stresses and deformations of the pubic symphysis; however, ligament strains, compressive and shear stresses in the interpubic disc, as well as posterior bending of the joint structure remained as potential sources of joint damage during automotive side impacts.

Three-dimensional finite element models of the human pubic symphysis with viscohyperelastic soft tissues.

Three-dimensional finite element (FE) models of human pubic symphyses were constructed from computed tomography image data of one male and one female cadaver pelvis. The pubic bones, interpubic fibrocartilaginous disc and four pubic ligaments were segmented semi-automatically and meshed with hexahedral elements using automatic mesh generation schemes. A two-term viscoelastic Prony series, determined by curve fitting results of compressive creep experiments, was used to model the rate-dependent effects of the interpubic disc and the pubic ligaments. Three-parameter Mooney-Rivlin material coefficients were calculated for the discs using a heuristic FE approach based on average experimental joint compression data. Similarly, a transversely isotropic hyperelastic material model was applied to the ligaments to capture average tensile responses. Linear elastic isotropic properties were assigned to bone. The applicability of the resulting models was tested in bending simulations in four directions and in tensile tests of varying load rates. The model-predicted results correlated reasonably with the joint bending stiffnesses and rate-dependent tensile responses measured in experiments, supporting the validity of the estimated material coefficients and overall modeling approach. This study represents an important and necessary step in the eventual development of biofidelic pelvis models to investigate symphysis response under high-energy impact conditions, such as motor vehicle collisions.

Negative pressure wound therapy to treat hematomas and surgical incisions following high-energy trauma.

PURPOSE: To evaluate the use of negative pressure wound therapy (NPWT) to augment healing of surgical incisions and hematomas after high-energy trauma. MATERIALS: This study is a prospective randomized evaluation of NPWT in trauma patients, randomizing patients with draining hematomas to either a pressure dressing (group A) or a VAC (group B). Additionally, patients with calcaneus, pilon, and high-energy tibial plateau fractures were randomized to either a standard postoperative dressing or a VAC over the sutures. RESULTS: There were 44 patients randomized into the hematoma study. Group A drained a mean of 3.1 days, compared with only 1.6 days for group B. This difference was significant (p=0.03). The infection rate for group A was 16%, compared with 8% in group B. An additional 44 patients have been randomized into the fracture study. Again, a significant difference (p=0.02) was present when comparing drainage in group A (4.8 days) and group B (1.8 days). No significant difference was present at current enrollment for infection or wound breakdown. DISCUSSION: NPWT has been used on many complex traumatic wounds. Potential mechanisms of action include angiogenesis, increased blood flow, and decreased interstitial fluid. This ongoing randomized study has demonstrated decreased drainage and improved wound healing following both hematomas and severe fractures.

Prophylaxis against deep-vein thrombosis following trauma: a prospective, randomized comparison of mechanical and pharmacologic prophylaxis.

BACKGROUND: Deep-vein thrombosis following skeletal trauma is an important yet poorly studied issue. The purpose of the present study was to evaluate the efficacy of two different strategies for prophylaxis against deep-vein thrombosis and pulmonary embolus following blunt skeletal trauma. METHODS: Two hundred and twenty-four inpatients were enrolled in a prospective, randomized study investigating venous thromboembolic disease following trauma. Two hundred patients completed the study, which compared two different regimens of prophylaxis. The patients in Group A received enoxaparin (30 mg, administered subcutaneously twice a day) starting twenty-four to forty-eight hours after blunt trauma. The patients in Group B were managed with pulsatile foot pumps at the time of admission combined with enoxaparin on a delayed basis. All patients were screened with magnetic resonance venography and ultrasonography before discharge. RESULTS: There were ninety-seven patients in Group A and 103 patients in Group B. Twenty-two patients (including thirteen in Group A and nine in Group B) had development of deep-vein thrombosis, with two (both in Group A) also having development of pulmonary embolism. The prevalence of deep-vein thrombosis was 11% for the whole series, 13.4% for Group A, and 8.7% for Group B; the difference between Groups A and B was not significant. There were eleven large or occlusive clots (prevalence, 11.3%) in Group A, compared with only three (prevalence, 2.9%) in Group B (p = 0.025). The prevalence of pulmonary embolism was 2.1% in Group A and 0% in Group B. Wound complications occurred in twenty-one patients in Group A, compared with twenty patients in Group B. Patients who had development of deep-vein thrombosis during the inpatient portion of the study required a mean of 7.4 units of blood during hospitalization, compared with 3.9 units of blood for those who did not (p < 0.05). CONCLUSIONS: Our results indicate that early mechanical prophylaxis with foot pumps and the addition of enoxaparin on a delayed basis is a very successful strategy for prophylaxis against venous thromboembolic disease following serious musculoskeletal injury. The prevalence of large or occlusive deep-vein thromboses among patients who had been managed with this protocol was significantly less than that among patients who had been managed with enoxaparin alone.

Contact pressures in the flexed hip joint during lateral trochanteric loading.

Acetabular fractures are an especially problematic outcome of motor vehicle side impacts. While fracture type has been correlated with impact direction and femoral orientation, actual contact pressures in the hip joint have not been quantified for lateral loading conditions. In the present study, we used pressure sensitive film to measure contact areas and pressures in seven hip joints from four cadavers under quasi-static lateral loading through the greater trochanter. The aim was to quantify the interactions of the femoral head with the acetabulum associated with variations in femoral orientation. Three angles of hip flexion (80 degrees , 90 degrees , 100 degrees ) and hip abduction (-10 degrees , 0 degrees , 10 degrees ) were tested, producing nine test orientations for each joint. We observed that contact areas, pressures, and forces varied significantly with femoral orientation for the adducted hip. The principal locations of load transmission were in the anterior and posterior regions of the acetabulum. For the abducted femur, contact pressures were concentrated anteriorly, and with increased adduction, anterior contact pressures diminished while posterior and superior pressures increased. The movement of pressure sites was consistent with mechanisms of acetabular fractures described by Letournel and Judet and provides new data for validation of finite element models of the pelvis in side impact.

Effects of trochanteric soft tissues and bone density on fracture of the female pelvis in experimental side impacts.

Pelvic fractures continue to be a source of morbidity and mortality for occupants in motor vehicle side impacts, especially among women. Previous studies have produced fracture tolerances for the female pelvis, yet the roles of soft tissues and bone quality remain unclear. Presently, we studied the influence of trochanteric soft tissue thickness (T) and total hip bone mineral density (BMD) on pelvic fracture of 10 female human pelves subject to lateral impact centered over the greater trochanter. Multiple impacts of increasing severity were performed and impact force, energy, impulse, compression, and viscous criteria were quantified. BMD and T were found to be additive predictors of the fracture force. For a given BMD, the force to fracture was significantly higher than that found previously using isolated pelvic bones. Impulse was found to positively correlate with T; however, maximum compression, viscous criterion, and energy to fracture were independent of BMD and T. The force tolerance at 25% probability of fracture found presently (3.16 kN) is substantially below previously reported values. The results suggest that the trochanteric soft tissue thickness and total hip BMD have a significant bearing on fracture outcome for the female pelvis in automotive side impact.

Current orthopaedic treatment of ballistic injuries.

The purpose of this review is to examine current orthopaedic treatment of gunshot wounds. Surgeons are increasingly confronted by gunshot wounds that occur in both military and civilian settings. Much of the published work has been from military settings. In the United States, low-energy gunshot wounds are very common, and their incidence is increasing elsewhere in the world. Current treatment and its rationale is reviewed and a systematic approach to the assessment and treatment of these injuries is offered, taking into account the entirety of the injury, rather than simply the velocity of the missile.

Ballistics: a primer for the surgeon.

The purpose of this paper is to review the literature on ballistics and to sort through the plethora of myth and popular opinion. The trauma surgeon is increasingly faced with gunshot wounds. Knowledge of ballistics is important to help in assessing the patterns of wounds that are seen. There are many factors that affect the flight of a bullet to its target. Many of these factors also affect the behaviour of the bullet after it strikes the target. It is primarily these factors that interest the surgeon.

Sternal approximation for bilateral anterolateral transsternal thoracotomy for lung transplantation.

The traditional incision for bilateral sequential lung transplantation is the bilateral anterolateral transsternal thoracotomy with approximation of the sternal fragments with interrupted stainless steel wire loops; this technique may be associated with an unacceptable incidence of postoperative sternal disruption causing chronic pain and deformity. Approximation of the sternal ends was achieved with peristernal cables that passed behind the sternum two intercostal spaces above and below the sternal division, which were then passed through metal sleeves in front of the sternum, the cables tensioned, and the sleeves then crimped. Forty-seven patients underwent sternal closure with this method, and satisfactory bone union occurred in all patients. Six patients underwent removal of the peristernal cables: 1 for infection (with satisfactory bone union after the removal of the cables), 3 for cosmetic reasons, 1 during the performance of a median sternotomy for an aortic valve replacement, and 1 in a patient who requested removal before commencing participation in football. This technique of peristernal cable approximation of sternal ends has successfully eliminated the problem of sternal disruption associated with this incision and is a useful alternative for preventing this complication after bilateral lung transplantation.

The less invasive stabilization system in the treatment of complex fractures of the tibial plateau: short-term results.

OBJECTIVES: To report on the use of a new plating system in the treatment of high-energy tibial plateau fractures using minimally invasive stabilization techniques. DESIGN: Prospective, consecutive patient series. SETTING: University Level I trauma center. PATIENTS: Thirty-seven patients with 39 fractures of the tibial plateau were treated using specialty plates. All fractures were OTA class 41C. Ten of the fractures were open, including eight Gustilo and Anderson Type IIIA and two Type IIIB. Thirty-three patients with 34 fractures had follow-up of at least 12 months. INTERVENTION: Internal fixation with the Less Invasive Stabilization System (LISS, Synthes USA, Paoli, PA) using minimally invasive techniques. MAIN OUTCOME MANAGEMENT: To determine clinical outcome, time to union, fracture alignment, articular step-off, incidence of complications, Short Form-36 outcome scores, and Lysholm knee scores in patients with associated ligament injuries. RESULTS: All 34 of the fractures healed without additional surgical intervention or bone grafting. The mean follow-up in our series was 21 months, with a range of 12 to 38 months. Twenty-nine patients with 30 fractures had follow-up of greater than 1 year. The average time to radiographic callus was 6.1 weeks, and the average time to complete union was 15.6 weeks. The articular step-off average was 0.8 mm, with a range of 0 to 5 mm. The postoperative alignment demonstrated 1 patient with a malalignment of 5 degrees procurvatum and 1 patient with 4 degrees of valgus. There were two superficial wound infections and no cases of deep infection or osteomyelitis. CONCLUSIONS: The use of LISS plates appears to stabilize complex fractures of the tibial plateau with a low incidence of complications. The LISS system functioned well in maintaining alignment and obtaining union in these high-energy fractures.

Restraint use and lower extremity fractures in frontal motor vehicle collisions.

BACKGROUND: Seat belts and air bags have been shown to significantly reduce morbidity and mortality following MVCs. Research suggests that restraint use does not protect against lower extremity fracture; however, no population-based studies of this association exist. The purpose of this study is to compare the effectiveness of combined seat belt and airbag restraint systems with airbag alone, seat belt alone, and no restraints with respect to incidence and location of lower extremity fractures. METHODS: A retrospective analysis of front seat occupants involved in police-reported, tow-away frontal MVCs was conducted using data from the 1995 through 2000 National Automotive Sampling System (NASS). Incidence and relative risk (RR) of fracture to specific bony regions were measured according to seat belt use and airbag deployment. RESULTS: Compared with unrestrained occupants, occupants restrained with airbag only had significantly higher risk for all types of lower extremity fractures whereas those occupants restrained with either seat belt only or seat belt and airbag had lower risk of fracture. The greatest difference was seen with tibia/fibula fractures in airbag only (RR, 2.14) but this trend continued to be significant with femur and pelvic fractures (RR, 1.13 and 1.23, respectively). CONCLUSION: While airbags may reduce the risk of death when used alone or in combination with seat belts, the results of this study demonstrate that air bags increase the risk of lower extremity fractures when used as the sole method of passenger protection. Also, they may do so differentially according to skeletal region. This data strongly support the consideration of developing accessory knee bolster airbags to prevent the "submarining" or sliding under the airbag that may be responsible for this finding.

Nonunions of the humerus.

Humerus fractures comprise 5% to 8% of all fractures. Nonunions are uncommon, but when they occur, they present a challenge to the orthopaedic surgeon and often are debilitating to patients. There are risk factors that may predispose patients to nonunion. Many methods of treating these nonunions have been described with varying degrees of success. We review the literature concerning the treatment of proximal, midshaft, and distal humeral nonunions and describe our treatment protocol based on the literature.

Intramedullary nailing of humeral shaft fractures with a locking flexible nail.

BACKGROUND: Studies on intramedullary nailing of humeral shaft fractures in the orthopaedic literature have shown mixed results. The purpose of this investigation was to document the clinical outcome and complications associated with the use of a new flexible, locking intramedullary nail that can be implanted in the humerus in either a retrograde or an antegrade manner without violating the rotator cuff mechanism or damaging the articular surface of the humeral head. METHODS: Fifty consecutive patients with fifty-one humeral shaft fractures were entered into our prospective clinical outcome study. The fracture was classified on the basis of the anatomic location and pattern. Implant positioning and fracture alignment were assessed postoperatively. Complications were recorded, and the time to union was measured. Shoulder function was evaluated with use of a combination of the Constant shoulder score, Short Form-36 (SF-36) clinical outcome data, range-of-motion measurements, and a subjective pain-rating scale. RESULTS: Forty-one patients with forty-two fractures had an adequate duration of clinical follow-up (a mean of twenty-two months) for analysis. Thirty-nine fractures healed, with a mean time to clinical union of twelve weeks (range, four to fifty weeks). Thirty-eight of the forty-two shoulders had minimal or no pain. Thirty-six shoulders had a full range of motion. The mean Constant shoulder score was 90 points. Four patients had five complications, which included two nonunions, two hardware failures, and one wound infection. All four patients had been managed with a 7.5-mm nail. A multivariate analysis demonstrated that an age of more than fifty years was associated with a lower Constant score and that the occurrence of a complication was associated with a lower physical component score on the SF-36. CONCLUSIONS: The flexible humeral nail allows both retrograde and antegrade implantation and static locking. Nail insertion can be accomplished without violating the rotator cuff or damaging the articular surface of the humeral head. Although the nail functioned well in most of our patients, the use of a small-diameter (7.5-mm) nail was associated with a higher complication rate. This implant should be used with caution in any patient with a medullary canal diameter of

Use of a hinged external knee fixator after surgery for knee dislocation.

PURPOSE: This study documents short-term clinical outcomes in patients with knee dislocations after blunt trauma and evaluates the compass knee hinge (CKH) external fixator for their treatment. TYPE OF STUDY: Nonrandomized prospective functional outcome study. METHODS: Forty patients with 43 knee dislocations were evaluated. Twelve knees underwent ligament reconstruction followed by placement of a CKH; this was group A. Group B included 27 knees that underwent the same treatment and rehabilitation protocol except that an external brace was used rather than a CKH. RESULTS: Thirty-six patients with 39 knee dislocations underwent follow-up ranging from 14 to 41 months (mean, 24). Four patients with 4 knee dislocations were lost to follow-up (1 group A, 3 group B). Group A underwent 27 knee ligament procedures with 2 (7%) failures based on clinical examination. Group B underwent 102 ligament procedures with 30 (29%) failures (P <.05). Anterior cruciate ligament (ACL) reconstruction revealed that 7 group A patients experienced 1 (14%) failure and 25 Group B patients experienced 7 (28%) failures. Posterior cruciate ligament (PCL) reconstruction in 7 group A patients included no failures, and 20 PCL reconstructions in group B included 1 failure. Reconstruction of the posterolateral corner (PLC) yielded no failures in 2 group A patients and 5 (25%) of 20 in group B. Repair of 8 PLCs in group A yielded 1 (12.5%) failure and 26 PLC repairs in group B had 14 (54%; P =.05). SF-36 data revealed low mean values with no significant differences between groups with current enrollment. CONCLUSIONS: Knee dislocation after blunt trauma requires aggressive surgical treatment and physical therapy. In the short-term evaluation, the CKH allows aggressive physical therapy without placing repaired or reconstructed ligaments under high stresses that can result in failure.

Pelvic trauma in rapidly fatal motor vehicle accidents.

OBJECTIVE: To study the incidence and nature of pelvic fractures in rapidly fatal automobile accidents. DESIGN: Retrospective. SETTING: County Medical Examiner's Office. PATIENTS: The files of 255 consecutive motor vehicle accident fatalities examined at the Jefferson County Coroner/Medical Examiner's office (study period 1996-1998) were reviewed. We correlated this information with our previous findings, derived from a review of 392 such cases (study period 1994-1996). RESULTS: Approximately 25% of decedents involved in rapidly fatal automobile accidents sustained pelvic fractures. In 93% of the cases, postmortem radiographs were available and suitable for scoring according to the Orthopaedic Trauma Association nomenclature. The distribution of pelvic fractures by type was type A, 16%; type B, 32%; and type C, 52%, with the most common pelvic fracture being type C1 (26%). Additionally, pedestrians and motorcyclists were twice as likely to sustain a pelvic fracture, and the severity of pelvic fracture type seemed to correlate with increasing speed of the automobile. No correlation between drug use or direction of impact and incidence or type of pelvic fracture was observed. Compared with published studies on survivors of automobile accidents, our data suggest that pelvic injuries may tend to be more severe in victims who do not survive to hospitalization. CONCLUSIONS: Our data indicate that current estimates about the mortality of pelvic fractures may be faulty due to exclusion of victims who fail to survive to hospitalization. This series suggests that an appreciation of the full spectrum of pelvic ring disruptions requires collaboration between orthopaedic surgeons and forensic pathologists.

The association between occupant restraint systems and risk of injury in frontal motor vehicle collisions.

BACKGROUND: An evaluation of seat belt use and airbag deployment, either alone or in combination, on risk of injury to specific body regions has yet to be completed. METHODS: A retrospective cohort study of front seat occupants involved in police-reported, tow-away, frontal motor vehicle collisions using data from the 1995 through 2000 National Automotive Sampling System was conducted. Only vehicles with a change in velocity (delta-V) of >/= 15 km/h were included. Risk of injury (Abbreviated Injury Scale score >/= 2) to specific body regions was compared according to seat belt use and airbag deployment. RESULTS: Compared with completely unrestrained occupants, those using a seat belt alone or in combination with an airbag had a reduced overall risk of injury (relative risk, 0.42 and 0.71, respectively); no association was observed for those restrained with an airbag only (relative risk, 0.98). This pattern of results was similar for specific body regions with the exception of the lower extremity, wherein a significantly increased risk was observed for airbag deployment alone. CONCLUSION: Airbag deployment does not appear to significantly reduce the risk of injury either alone or in combination with seat belts. Airbag deployment without associated seat belt use may increase the risk of lower extremity injury.

Relationship between age and lower extremity fractures in frontal motor vehicle collisions.

BACKGROUND: Older adults (aged > or = 65 years) represent the single fastest growing segment of the United States population and will comprise one in five Americans during the third decade of this century. As this population segment rapidly expands, lower extremity fractures (LE Fx) and their associated disability will become a greater public health concern. The purpose of this study was to quantify the risk for LE Fx from motor vehicle collisions (MVCs) according to age. METHODS: The 1995 to 2000 National Automotive Sampling System data files were used. Study entry was limited to front-seat occupants involved in frontal MVCs. Risk ratios for LE Fx and age were adjusted for gender, driver versus passenger, seat belt use, airbag deployment, delta-V, intrusion, and vehicle type. RESULTS: Beginning in the fourth decade, there was a trend of higher relative risk for LE Fx with age that reached statistical significance in the seventh decade of life. CONCLUSION: This study documented an increased risk of LE Fx in older MVC occupants. Efforts to prevent these disabling injuries and to better protect occupants' lower extremities in MVCs should include improved vehicle design and reevaluation of the existing federal motor vehicle safety standards.

Bone mineral density correlates with fracture load in experimental side impacts of the pelvis.

Pelvic fractures resulting from automotive side impacts are associated with high mortality and morbidity, as well as substantial economic costs. Previous experimental studies have produced varying results regarding the tolerance of the pelvis to lateral force and compression. While bone mineral density (BMD) has been shown to correlate with fracture loads in the proximal femur, no such correlation has been established for the pelvis. Presently, we studied the relationships between total hip BMD and impact response parameters in lateral impacts of twelve isolated human pelves. The results indicated that total hip BMD significantly correlated with fracture force, Fmax, and maximum ring compression, Cmax, of the fractured pelves. These findings are evidence that BMD may be useful in assessing the risk of pelvic fracture in automotive side impacts. Poor correlation was observed between total hip BMD and maximum viscous response, (VC)max, energy at fracture, Epeak, and time to fracture, tpeak. Mean Fmax and calculated tolerances for Cmax and (VC)max were lower than those established in previous studies using full cadavers, likely a result of our removal of soft tissues from the pelves prior to impact.