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.

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.

Deep-vein thrombosis in high-energy skeletal trauma despite thromboprophylaxis

We report the incidence and location of deep-vein thrombosis in 312 patients who had sustained high-energy, skeletal trauma. They were investigated using magnetic resonance venography and Duplex ultrasound.

Despite thromboprophylaxis, 36 (11.5%) developed venous thromboembolic disease with an incidence of 10% in those with non-pelvic trauma and 12.2% in the group with pelvic trauma. Of patients who developed deep-vein thrombosis, 13 of 27 in the pelvic group (48%) and only one of nine in the non-pelvic group (11%) had a definite pelvic deep-vein thrombosis. When compared with magnetic resonance venography, ultrasound had a false-negative rate of 77% in diagnosing pelvic deep-vein thrombosis. Its value in the pelvis was limited, although it was more accurate than magnetic resonance venography in diagnosing clots in the lower limbs. Additional screening may be needed to detect pelvic deep-vein thrombosis in patients with pelvic or acetabular fractures.

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.

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.

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.

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.

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.

Early versus Delayed Fixation of Pelvic Ring Fractures

This retrospective study reports outcomes, after early and delayed surgical stabilization of fractures of the pelvic ring, in terms of pulmonary complications, length of hospital stay, and cost of hospitalization. The hospital course of 151 patients admitted to an academic teaching hospital who sustained acute fractures of the pelvic ring between June 1996 and December 2000 was reviewed. Patient demographics, Injury Severity Score (ISS), timing of operative fixation, and the incidence of pulmonary complications were analyzed. Radiographs were reviewed and fractures classified according to the modified Tile system. Tile fracture types B and C patients who underwent fixation within 1 week of injury (n = 71) were compared to those in whom surgery was delayed (n = 28). Adjusting for the ISS, early-repair patients had a lower risk of pulmonary complications (RR = 0.49, 95% CI = 0.25-0.96), a reduced length of hospital stay (12.2 vs. 20.5 days; P = 0.0005), and overall reduced cost of care ($57,084 vs. $158,625; P = 0.0317). Pelvic ring fixation within the first week of injury results in significantly reduced incidence of pulmonary complication, hospital stay, and cost of care regardless of injury severity. The coordinated team approach to insure prompt resuscitation, stabilization, and operative fixation results in more optimal patient outcomes.

Early versus delayed fixation of pelvic ring fractures

This retrospective study reports outcomes, after early and delayed surgical stabilization of fractures of the pelvic ring, in terms of pulmonary complications, length of hospital stay, and cost of hospitalization. The hospital course of 151 patients admitted to an academic teaching hospital who sustained acute fractures of the pelvic ring between June 1996 and December 2000 was reviewed. Patient demographics, Injury Severity Score (ISS), timing of operative fixation, and the incidence of pulmonary complications were analyzed. Radiographs were reviewed and fractures classified according to the modified Tile system. Tile fracture types B and C patients who underwent fixation within 1 week of injury (n = 71) were compared to those in whom surgery was delayed (n = 28). Adjusting for the ISS, early-repair patients had a lower risk of pulmonary complications (RR = 0.49, 95% CI = 0.25-0.96), a reduced length of hospital stay (12.2 vs. 20.5 days; P = 0.0005), and overall reduced cost of care (57,084 dollars vs. 158,625 dollars; P = 0.0317). Pelvic ring fixation within the first week of injury results in significantly reduced incidence of pulmonary complication, hospital stay, and cost of care regardless of injury severity. The coordinated team approach to insure prompt resuscitation, stabilization, and operative fixation results in more optimal patient outcomes.

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 <or=8 mm.

Fracture stabilization of proximal tibial fractures with the proximal tibial LISS: early experience in Birmingham, Alabama (USA)

This study is a prospective evaluation of the Less Invasive Stabilization System (LTSS) for the treatment of high-energy tibial plateau and proximal tibial fractures treated between November, 1998 and June, 2000. Thirty-two patients sustained thirty-five acute fractures of the tibial plateau (25) or proximal tibia (10). These patients were injured primarily in blunt trauma accidents, with eighteen having multiple fractures, fifteen having ipsilateral extremity fractures, and eleven having major knee ligament injuries. Seventeen patients had open fractures. Thirty-four patients healed their fractures, with one developing a nonunion. Two patients developed infections, both following Type III open fractures. Final range of motion averaged 2 to 116 degrees. Alignment was well maintained, with no patient losing the alignment that was obtained in the operating room. The tibial LISS system worked well at stabilizing difficult fractures of the tibial plateau and proximal tibia with a low incidence of complications in this preliminary study with short-term follow-up.

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.

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.

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.

Heterotopic ossification associated with knee dislocation

PURPOSE

The purpose of this study was to determine the prevalence of heterotopic ossification following knee dislocation.

TYPE OF STUDY

Prospective clinical evaluation and a retrospective chart review.

METHODS

This study evaluated 57 knees in 55 patients who sustained high-energy blunt trauma with resultant knee dislocations. Radiographs were reviewed by 2 of the authors (J.P.S., T.C.W.), and the incidence of heterotopic ossification (HO) was documented. Additionally, patients were classified regarding the degree of HO on a scale from 0 to 4. One is punctate calcification, 2 is HO involving less than 50% of the joint space; 3 is HO involving more than 50%; and 4 is ankylosis of the joint.

RESULTS

Thirteen patients with 15 knee dislocations developed HO. The incidence of HO was 26%. Seven knees demonstrated severe HO (grade 3 or 4) which represented an incidence of 12% of all knee dislocations. Injury severity score for both groups was 18, documenting that the patients in this study represent multiple trauma patients. There was no significant difference in the incidence of HO based on mechanism of injury with the current number enrolled in the study. However, 60% (3 of 5) of patients involved in a motor vehicle versus pedestrian accident developed HO. There was a significant increase in the incidence of arthrofibrosis in patients with severe HO (P <.05). Patients with significant HO had a mean flexion of 97 degrees, compared with flexion of 117 degrees in patients with no or mild HO. This difference was borderline significant (P =.058). There was no difference between the groups in mean extension. There was a significant increase in knee HO in patients with HO at another anatomic site (P =.01).

CONCLUSIONS

HO is a common problem following knee dislocation. Of the 7 knees with severe HO, 5 developed HO medially, 4 developed HO posteriorly, 3 developed HO laterally, and only 1 had involvement anteriorly. A similar distribution was present in the patients with mild HO, with posterior and medial ossification being the most common. Five of the 7 severe HO cases involved at least 3 of the 4 sides (anterior, posterior, medial, or lateral) of the knee. Patients were evaluated for the presence of head injury and any relationship to the development of HO around the knee. There was no increased incidence of HO around the knee in our 10 patients with severe head injuries when compared with those with no head injury. There was also no increased incidence of HO in knee dislocations associated with periarticular fractures.

Analysis of the incidence of pelvic trauma in fatal automobile accidents

Pelvic fractures are frequent complications of motor vehicle accidents, and motor vehicle accidents are the most common cause of pelvic fracture. Although pelvic fractures are associated with considerable morbidity and mortality, there has traditionally been no attempt to grade or classify pelvic fractures during postmortem examination. The authors performed a retrospective study of cases examined at the Jefferson County Coroner/Medical Examiner Office from 1994 to 1996, reviewing investigative reports and autopsy findings. Radiographs were examined for the presence and Tile type of pelvic fracture. Pelvic fractures were identified in 88 of 392 cases (23%). In most (89%), the pelvic fracture was readily classified according to Tile type on the basis of radiographs and the inferred mechanism of injury. This study indicates that current estimates of the mortality of pelvic fractures are low because of the exclusion of individuals who do not survive to hospitalization. Furthermore, pelvic fractures in rapidly fatal motor vehicle accidents tend to be more severe than fractures in individuals who have a significant interval of survival. The presence and classification of pelvic fractures may be readily determined by radiographs in most cases. The Tile classification scheme is easy to apply and has important implications in the comparison of study groups.

Fixation failure in femoral neck fractures

Fixation of femoral neck fractures is associated with a higher incidence of complications than any other fracture. The rates of nonunion and avascular necrosis with open reduction and internal fixation continue to be unacceptably high. These complications are the main reason for resorting to primary endoprosthetic replacement of the femoral head in the presence of displaced fractures in elderly patients. However, with the increasing life span of the patients with these prostheses, late complications of endoprosthetic replacement of the femoral head are becoming significant. With these complications, it may be argued that the most cost-effective solution to the femoral neck fracture in the majority of patients is open reduction and internal fixation, with elective conversion, when necessary, to total hip arthroplasty in patients who have a complication. Because the literature does not contain a systematic review of reasons for failure of internal fixation, the authors will attempt to review the common means of failure of internal fixation in young and older patients in an attempt to better understand and prevent these complications.

Mechanical prophylaxis against deep-vein thrombosis after pelvic and acetabular fractures

BACKGROUND

Deep-vein thrombosis is a common complication following pelvic and acetabular fractures. The hypothesis of this study was that pulsatile mechanical compression is superior to standard sequential mechanical compression for decreasing the prevalence of deep-vein thrombosis in patients with pelvic or acetabular fracture.

METHODS

A prospective, randomized, blinded study of two methods of mechanical prophylaxis against deep-vein thrombosis was conducted. One hundred and seven patients were randomized into either Group A (fifty-four patients), in which a thigh-calf low-pressure sequential-compression device was used, or Group B (fifty-three patients), in which a calf-foot high-pressure pulsatile-compression pump was used. All patients underwent duplex ultrasonography and magnetic resonance venography. The two groups were comparable with regard to demographics, fracture type, fracture treatment, time from the injury to the prophylaxis, and patient compliance.

RESULTS

Deep-vein thrombosis developed in ten patients (19%) in Group A, with seven (13%) having a large or occlusive clot and one (2%) having a documented pulmonary embolism. Deep-vein thrombosis developed in five patients (9%) in Group B, with two (4%) having a large or occlusive clot and none having a documented pulmonary embolism. Nine of the nineteen detected thromboses were in the deep pelvic veins. The difference in the prevalence of large or occlusive clots between the two groups demonstrated a trend but, with the numbers available, was not significant (p = 0.16). Increased patient age and the time elapsed from the injury to the surgery were found to be associated with higher rates of thrombosis.

CONCLUSIONS

Pulsatile compression was associated with fewer deep-vein thromboses than was standard compression, with the difference representing a trend but not reaching significance with the number of patients studied.

Elastic and viscoelastic properties of the human pubic symphysis joint: effects of lateral impact joint loading

The human pelvis is susceptible to severe injury in vehicle side impacts owing to its close proximity to the intruding door and unnatural loading through the greater trochanter. Whereas fractures of the pelvic bones are diagnosed with routine radiographs (x-rays) and computerized tomography (CT scans), non-displaced damage to the soft tissues of pubic symphysis joints may go undetected. If present, trauma-induced joint laxity may cause pelvic instability, which has been associated with pelvic pain in non-traumatic cases. In this study, mechanical properties of cadaveric pubic symphysis joints from twelve normal and eight laterally impacted pelves were compared. Axial stiffness and creep responses of these isolated symphyses were measured in tension and compression (perpendicular to the joint). Bending stiffness was determined in four primary directions followed by a tension-to-failure test. Loading rate and direction correlated significantly (p<0.05) with stiffness and tensile strength of the unimpacted joints, more so than donor age or gender. The impacted joints had significantly lower stiffness in tension (p <0.04), compression (p<0.003), and posterior bending (p<0.03), and more creep under a compressive step load (p<0.008) than the unimpacted specimens. Tensile strength was reduced following impact, however, not significantly. We concluded that the symphysis joints from the impacted pelves had greater laxity, which may correlate with post-traumatic pelvic pain in some motor vehicle crash occupants.

Functional outcome of patients with femoral head fractures associated with hip dislocations

Fracture of the femoral head after hip dislocation is a relatively rare injury often associated with a poor functional outcome. Twenty-six patients who sustained femoral head fractures were evaluated using radiographs, clinical examinations, and a validated outcome scoring system. The Short Form-12 was used to assess functional outcome. Patients whose fractures were stabilized with 3-mm cannulated screws and washers had a poor functional outcome. When evaluated with an odds ratio analysis, the use of Kocher-Langenbeck posterior approach was associated with a 3.2 times higher incidence of the patients having avascular necrosis develop when compared with the Smith-Petersen approach. A literature review combined with the current series confirms that the principles of early reduction of hip dislocation, early stabilization, anatomic reduction of the fracture, and rigid fixation are critical principles to attain good results. The Brumback classification system provides superior differentiation of different fracture types when compared with the Pipkin classification. The Smith-Petersen anterior surgical approach is recommended for the majority of patients with femoral head fractures. Three-millimeter cannulated screws with threaded washers are contraindicated for use in stabilizing femoral head fractures, and should not be used in any joint because of dissociation between the screw and the washer.

A review of the treatment of hip dislocations associated with acetabular fractures

Traumatic dislocation of the hip is an extremely severe injury. Although previously considered an uncommon lesion, it now is seen more often as a result of motor vehicle accidents. In most cases, dislocation of the hip is associated with fractures of the acetabulum, which ultimately can result in a higher incidence of complications than the complications observed in pure simple dislocations. Early recognition and prompt closed reduction of the dislocated hip constitute the cornerstone of proper treatment of this injury. Once the dislocation is reduced, definitive treatment of the acetabular fracture can be delayed to obtain a precise diagnostic evaluation. If surgical reconstruction of the acetabular fracture is indicated, it is done best in the first 10 days after the injury. A few patients in whom nonconcentric reduction, failed closed reduction, or impaired neurologic status occurs after reduction will require early open reduction and internal fixation of the fracture. Complications can be caused by the initial injury or by the treatment. Avascular necrosis of the femoral head, degenerative osteoarthritis, and heterotopic ossification are the main complications encountered in patients with unsatisfactory final results. Despite a perfect reduction of the hip dislocation and anatomic reduction of the acetabular fracture, a significant degenerative process of the hip is expected when the patient is assessed at long-term followup.

A prospective evaluation of the timing of postoperative radiotherapy for preventing heterotopic ossification following traumatic acetabular fractures

PURPOSE

Preoperative and immediate postoperative irradiation of traumatic acetabular fractures (TAF), although known to reduce heterotopic ossification (HO), can cause significant organizational and logistic difficulties. We sought to determine an acceptable time interval between surgery and radiation without compromising control, as well as to update our large experience and to further validate our treatment philosophy.

METHODS AND MATERIALS

Beginning in June 1995, we began a prospective study, irradiating 152 patients on postoperative days 1, 2, or 3. There were also 17 patients delayed further secondary to medical difficulties.

RESULTS

All patients treated since June 1995 received 700 cGy/1 fx. Fifty-eight patients received radiation within 24 hours of surgery, 41 within 2 days, 53 within 3 days, 13 within 4 days, and 4 were delayed further. Delaying irradiation for up to 4 days postoperatively caused no statistical increase in HO (p = 0.625). Of 263 patients in our retrospective cohort, HO occurred in 5.3% of patients who received irradiation versus 60% of patients who did not.

CONCLUSION

In our prospective study, we noted no perceptible increase in HO with up to a 3-day interval between surgery and radiotherapy. This allows a more structured treatment schedule and allows the patient more time to heal and recover. Updated results from our overall series continue to demonstrate that adjuvant radiation decreases the incidence and severity of HO after TAF.

Acetabular fracture patterns: associations with motor vehicle crash information

BACKGROUND

Motor vehicle crashes are the most common cause of acetabular fractures, which have been associated with significant morbidity and mortality.

METHODS

To date, medical and collision information has been collected on 83 acetabular fracture patients treated at the University of Alabama at Birmingham's Level I trauma center. The fractures were grouped according to the Judet-Letournel classification scheme and investigated for correlation with age, sex, vehicle type, impact direction, and seat-belt use.

RESULTS

The database included 41 women and 42 men with a combined average age of 32.8 years. Femoral shaft axis loading fractures correlated significantly with male sex, trucks, and frontal impacts. Greater trochanter loading fractures occurred statistically more frequently in side impacts. Women received a significant higher percentage of off-axis loading fractures, which were associated more in angled frontal impacts.

CONCLUSION

Acetabular fracture type strongly correlated with impact direction, supporting the fracture mechanisms proposed by Judet and Letournel.

Controversies in acetabular fractures

Open reduction and internal fixation has become the standard of care for the treatment of most displaced acetabular fractures. As surgical techniques have become refined, long term results of surgical fixation have improved. During the past 10 to 15 years, several controversies have surfaced in the orthopaedic literature regarding the treatment of acetabular fractures. The recent literature regarding acetabular fixation was reviewed. Controversies include the most efficacious surgical approach for complex acetabular fractures; the effectiveness of intraoperative sciatic nerve monitoring; the most effective method of prophylaxis against deep vein thrombosis; and the indications for and method of prophylaxis against heterotopic bone formation.

The management of complex orthopedic injuries

As advancements are made in the prevention of automobile fatalities, an increase in the incidence of pelvic and lower extremity injuries has occurred. These remain the leading causes of impairment and loss of years of productive life. Pelvic trauma has a high initial mortality rate when severe. However, with early resuscitation and transport, more survivors arrive in our trauma centers harboring these injuries. Owing to early stabilization and mobilization of the traumatized patient, a decrease in complications in these patients has been noted. Both the trauma surgeon and the orthopedic trauma surgeon should work as a team and remain in continuous communication during the treatment of these patients. Open fractures are among the most difficult problems to manage; early and aggressive decisions can prevent a lifetime of complications and physical impairment. As previously stated, to obtain good outcomes, open fractures must be treated initially at the accident scene followed by timely transport to the trauma center for definitive care. It must be remembered that the golden time to prevent major complications is 6 hours. Intra-articular fractures of the lower extremity involve a major weight bearing joint. Post-traumatic arthritis and impairment develop in joints where joint congruity is not achieved. To preserve normal function, there should be articular congruity, stable fixation, axial alignment with the rest of the extremity, and restoration of full range of motion. Immediate stabilization of long bone fractures has many advantages in the multiply injured patient, such as improved long-term function, prevention of deep venous thrombosis and decubitus ulcer, decreased need for analgesia, and reduction in the incidence of adult respiratory distress syndrome and fat emboli. Patients with femoral shaft fractures should undergo immediate stabilization of the fracture within 24 hours of injury. We have presented a series of orthopedic injuries that have high mortality and high morbidity which, if not treated expediently, yield a high degree of impairment.

Lawn mower injuries in children: a preventable impairment

Every year there are seven million new lawn mowers purchased in the United States, each of which is capable of injuring young children, especially those > 14 years of age. A total of 33 children injured by a lawn mower were reviewed to identify the mechanism of injury, to determine the factors responsible for the accident, to determine an effective treatment regime, and to evaluate the permanent impairment for these patients. Classified according to their mechanism of injury, 14 children were injured as bystanders, 13 injured as riders, and six injured as operators. Categorized according to the anatomical location of injury, there were eight head and eye injuries, 12 upper extremity injuries, and 13 lower extremity injuries. There were 13 amputations (39.3%). The treatment management was satisfactory, but 23 children had an impairment > 40% of the whole person. We believe that the incidence of these injuries can be reduced by public awareness. Each orthopaedic surgeon should take on the task of educating the public about the dangers and wounding capacity of these machines and instructing the proper safety precautions that should be taken when mowing the lawn, especially when children are involved. The bottom line is that children should not be allowed in the yard while the lawn is being mowed nor should they be allowed to mow the lawn until they are > or = 15 years of age.

Improved treatment of femoral shaft fractures in children utilizing the pontoon spica cast: a long-term follow-up

This prospective study looked at 91 pediatric femur fractures. Patients were randomized into two groups: (a) A traditional group treated with 3 weeks in traction followed by spica; and (b) a pontoon spica group in which patients were treated first with only a few days in traction and then with a 90-90 pins-in-plastic spica. The pontoon spica provides excellent short- and long-term results. These include (a) providing substantial cost savings; (b) causing much less inconvenience to the family and child; (c) reducing the number of inpatient days, thereby freeing hospital beds; (d) permitting early motion; (e) reducing the number of short-term complications; and (f) preventing excessive shortening while controlling rotation.

Extended iliofemoral versus triradiate approaches in management of associated acetabular fractures

From July 1988 to June 1991, 110 complex acetabular fractures were operatively treated. A triradiate approach was used in 38 patients and an extended iliofemoral approach in 21. The mean patient age was 32 years (range, 15-80 years). These 59 patients were followed for a minimum of 36 months postoperatively. The postoperative function state was evaluated according to D'Aubigne/Postel, and the results were: Excellent, 32 patients (54%); Very Good, 10 (17%); Good, 5 (8%); Fair, 4 (7%); and Poor, 8 (14%). Adequacy of acetabular reconstruction was evaluated from the anteroposterior, obturator oblique, and iliac oblique radiographs. All patients had excellent or good radiographic results (< 2 mm step off or gap). Iatrogenic sciatic nerve injury was seen in two patients with the triradiate and one with the extended iliofemoral approach. Deep infection was seen in one patient in the extended iliofemoral group and two in the triradiate group. Eight patients developed heterotopic ossification of Brooker Grade III or IV despite prophylactic treatment with indomethacin. Both approaches provided good visualization of complex acetabular fractures.

Bridging bone gaps with the Ilizarov technique. Biologic principles

For the treatment of bone gaps of less than 4 cm, cancellous autografting remains the treatment of choice. But for gaps exceeding 4 cm, the distraction osteogenesis is a viable option. The following conditions should be satisfied: (1) patient selection; (2) stable fixation; (3) osteotomy by corticotomy; (4) 7- to 14-day latency period before initiating distraction; and (5) a controlled rate and rhythm of distraction of 1 mm per day (0.25 mm, four times a day). This type of treatment leaves the pathologic focus alone, and bone healing occurs on the healthy bone. The quality of bone regenerate may be improved by a motorized unit and by better soft-tissue coverage using early grafts and flaps. Interface healing is probably improved by cancellous grafting and internal fixation after the transport period, thus decreasing the fixator time.

The use of the Ilizarov concept with the AO/ASIF tubular fixateur in the treatment of segmental defects

For the treatment of segmental defects of less than 4 cm, cancellous autografting remains the treatment of choice. Pedicled or free cortical grafts (fibula, ribs, iliac crest) often are not strong enough, particularly when used in the femur. Allografts, especially appealing because of the theoretic unlimited supply, should not be considered for segmental diaphyseal defects because they remain dead spacers, remodelled only very slowly and incompletely, and are often complicated by late infection. The technique of distraction histogenesis used by Putti and Anderson, improved and further differentiated towards corticotomy and fragment transport by Ilizarov, is a further possibility of treating long, segmental bone defects. Already clinical and experimental data clearly show that the effect of distraction histogenesis can be obtained using many different types of external fixators. Therefore, we should use as simple a fixator construction as possible. The standard unilateral sagittal frame we suggest is derived from a two-tube AO fixator using only a few additional elements. The majority of cases with segmental defects and minor additional axial or rotational deformities (which can be corrected primarily) can be treated with such a fixator. The quality of the regenerate may be improved with a motorized, continuous transport system and by better soft-tissue coverage using early flaps. Interface healing is very probably improved by cancellous grafting and internal fixation after the transport period, thus decreasing the fixator time.

Use of the AO/ASIF external fixator in children

Sixteen children with 20 fractures were treated with the AO/ASIF tubular fixator (Synthes, Ltd., Paoli, PA). Most of the fractures were open, but the fixator was also used in closed fractures in children with head injuries or other forms of trauma. There were 10 fractures of the tibia, 5 of the femur, 3 of the pelvis, and 2 involving the humerus. Average follow-up was 26 months, with the fixators in place for an average of 7 weeks. Fracture union occurred after an average of 16 weeks. This system is easier to apply, less complicated, and lighter than other types of fixators.

The etiology of valgus angulation after metaphyseal fractures of the tibia in children

We conducted a retrospective study of proximal metaphyseal fractures of the tibia in children who developed valgus deformities. We reviewed the cases in an effort to determine the most likely etiology of post-fracture tibia valga, which occurs despite careful treatment and follow-up. We reviewed seven major theories presented in the literature regarding the etiology of this problem. Our conclusion was that all the theories were not prerequisites for the development of valgus angulation, but rather may be secondary mechanisms. We suggest that the most likely primary mechanism is an increased vascular response causing an asymmetric growth stimulation of the medial metaphysis of the proximal tibia.

Closed interlocking nailing of the femur complicated by an intramedullary calcified lesion

The interlocking intramedullary nail has greatly expanded the indications for closed intramedullary nailing of the femur. We describe a complication caused by the presence of a calcified lesion located at the proximal metaphyseal-diaphyseal junction of the femur. This lesion could not be penetrated by hand reamers. We used a long 3.5-mm drill bit to place a hole in the infarct, which then allowed passage of the hand reamer. The operation then proceeded in the standard fashion without complications.

The Altdorf hip clamp

Forty-one osteotomies internally fixed with the Altdorf hip clamp were reviewed at Nemours Children's Hospital (Jacksonville, FL). They were divided according to pathology: cerebral palsy, 19 patients; congenital dislocated hip, 2 patients; Legg-Calvé-Perthes disease, 8 patients; and other, 2 patients. There were 15 boys and 18 girls, with an average age of 6.9 years (range 2.6-12 years). No intraoperative complications have been reported. Long-term complications are as follows: nonunion, one patient; superficial wound infection, one patient; and loss of position of greater than 15 degrees, two patients.