Biomechanical Analysis of Retrograde Flexible Intramedullary Nail Constructs in a Simulated Pediatric Femur Fracture Model.

BACKGROUND: Various flexible intramedullary nail (FIMN) constructs for pediatric femur fractures are described; however, no biomechanical study has compared stability of medial-lateral entry versus all-lateral entry retrograde nailing. Our purpose is to compare the rotational and bending stiffness of 2 different FIMN constructs and 2 different materials in a simulated pediatric femur fracture model. METHODS: Eighty adolescent-sized composite femurs were used to simulate transverse (40 femurs) and oblique (40 femurs) mid-diaphyseal fractures. Retrograde FIMN of the femurs was performed using either 3.5 mm titanium (Ti) or 3.5 mm stainless-steel (SS) flexible nails in 2 configurations: 2 "C"-shaped nails (CC) placed through medial and lateral entry sites or 1 "C"-shaped nail and 1 "S"-shaped nail (CS) placed through a single lateral entry site. Models were first tested in 10 cycles of axial rotation to ±1 N m of torque at a rate of 0.5 degrees/s under 36 kg of compression. Axial compression was performed and bending stiffness defined as the force required to achieve 10 degrees varus at the fracture site. RESULTS: No differences were noted in rotational stiffness comparing Ti and SS nails regardless of nail configuration or fracture pattern. Comparable rotational stability was found for CC and CS configurations with SS implants for both fracture patterns. The CS construct (0.60 N m/degree) was stiffer in rotation than the CC construct (0.41 N m/degree) with Ti implants in the transverse fracture model (P<0.005). SS nails provided greater bending stiffness than Ti nails in both oblique and transverse fracture patterns, regardless of nail construct. The all-lateral entry (CS) construct demonstrated statistically significant greater bending stiffness regardless of implant material or fracture pattern (P<0.03). CONCLUSIONS: An all-lateral entry (CS) FIMN construct demonstrated greater bending stiffness in both fracture patterns and materials. Ti and SS implants have comparable rotational stiffness in all fracture patterns and materials; however, SS nails were superior at resisting bending forces in both fracture patterns. CS nail configuration and SS implants demonstrated superior bending stiffness and rotational stiffness when compared with the more commonly used CC construct and Ti implants. LEVEL OF EVIDENCE: NA (biomechanical study).

Distal Femoral Valgus and Recurrent Traumatic Patellar Instability: Is an Isolated Varus Producing Distal Femoral Osteotomy a Treatment Option?

BACKGROUND: Genu valgum, a risk factor for recurrent patellofemoral instability, can be addressed with a varus producing distal femoral osteotomy (DFO). The purpose of this study is to report 3-year clinical and radiographic outcomes on a series of skeletally mature adolescents with traumatic patellofemoral instability and genu valgum who underwent a varus producing DFO. METHODS: Consecutive patients (n=11) who underwent an isolated DFO for recurrent traumatic patellar instability over a 4-year study period (2009 to 2012) were reviewed. All patients were below 19 years of age, skeletally mature, had ≥2 patellar dislocations, genu valgum (≥ zone II mechanical axis) and failed nonoperative treatment. Exclusion criteria included less than three-year follow-up, congenital or habitual patellar instability, osteotomy indicated for pathology other than patellar instability, or biplanar osteotomies. Demographic, clinical, and radiographic data were retrospectively analyzed. Recurrence of instability and outcome measures (Kujala and Tegner Activity Scale) were collected at final followed-up prospectively. RESULTS: Ten of 11 patients (average age, 16 y; range, 14 to 18 y; 4 male individuals: 7 female individuals) with an average follow-up of 4.25 years (range, 3.2 to 6.0 y) met inclusion criteria. The average body mass index (BMI) of all patients was 31.3 (range, 19.7 to 46.8) with 91% considered overweight (BMI>25) and 55% obese (BMI>30). The average preoperative lateral distal femoral angle was 75.4 degrees with an average correction of 10.4 degrees (range, 7 to 12 degrees) (P<0.001). Mean patellar height ratios were reduced; with Caton-Deschamps Index significantly reduced to 1.08 (range, 0.86 to 1.30) (P<0.005). The average postoperative Kujala score was 83.6 (range, 49 to 99) with 7 subjects (70%) reporting good to excellent function (Kujala > 80) and 8 (80%) having no further episodes of instability. The mean postoperative Tegner activity score was 5.5 (range, 3 to 7). CONCLUSIONS: A distal femoral varus producing osteotomy may change radiographic parameters associated with patellar instability and improve clinical outcomes by reducing symptomatic patellofemoral instability in this patient population. LEVEL OF EVIDENCE: Level IV.

Redefining Optimal Nail to Medullary Canal Diameter Ratio in Stainless Steel Flexible Intramedullary Nailing of Pediatric Femur Fractures.

PURPOSE: The ideal canal fill for flexible intramedullary fixation of pediatric femoral shaft fractures is considered to be 80% based upon relatively few clinical studies. The purpose of this study is to assess the relationship between the summed nail to intramedullary canal diameter (ND/MCD) ratio and alignment at radiographic union following flexible intramedullary nailing (FIMN) of pediatric femoral shaft fractures. METHODS: An Internal Review Board approved, retrospective review of a consecutive series of patients who sustained a femoral shaft fracture treated by retrograde, stainless steel FIMN was performed at a single level 1 pediatric trauma center from 2005 to 2012. Preoperative radiographs were analyzed to determine fracture pattern, location, and isthmic canal diameter. ND/MCD ratio was calculated using the sum of the known nail diameters and the measured isthmic diameter. Radiographs at bony union were reviewed to measure shortening, coronal angulation, and sagittal angulation. ND/MCD ratio was analyzed to determine correlative factors with final radiographic outcomes. RESULTS: In total, 261 children underwent retrograde FIMN at an average age of 8.2 years (range, 2.2 to 17.0 y). ND/MCD ratio of ≥80% was seen in 108 (41.4%) patients. When compared with those with <80% ND/MCD ratio, there were no significant differences in age (8.8 vs. 8.0 y), sex (76.9% vs. 71.0% males), or body mass index (18.5 vs. 17.2 kg/m). There were significantly more length unstable fractures in the <80% ND/MCD ratio group (49.4% vs. 29.7%; P<0.01). Radiographic outcome was no different with respect to coronal angulation (2.7 vs. 3.0 degrees), sagittal angulation (3.0 vs. 3.2 degrees), or shortening (2.5 vs. 4.1 mm). ND/MCD ratio of ≥70% was seen in 176 (67.4%) patients and, when compared with the <70% ND/MCD ratio group, there were no differences in shortening (3.3 vs. 3.9 mm), coronal angulation (2.8 vs. 3.0 degrees), or sagittal angulation (3.0 vs. 3.4 degrees). Finally, 6.9% of the population (18 patients) had ND/MCD ratios <60% and did not demonstrate a significant increase in shortening, coronal, or sagittal angulation compared with groups with higher ND/MCD ratios. No group had an increased rate of infection, implant removal, nonunion, or need for reoperation. CONCLUSIONS: In a large series of consecutive patients treated with retrograde stainless steel FIMN there does not appear to be any correlation between the ND/MCD ratio and radiographic outcome. Stainless steel flexible IM nails seem to maintain fracture alignment without an increase in complications at lower ND/MCD ratios than previously reported as "optimal." LEVEL OF EVIDENCE: Level III.

Two Techniques for Retrograde Flexible Intramedullary Fixation of Pediatric Femur Fractures: All-Lateral Entry Versus Medial and Lateral Entry Point.

BACKGROUND: Multiple techniques for flexible intramedullary nailing (FIMN) of pediatric femur fractures have been described. To our knowledge, no study has compared combined medial-lateral (ML) entry versus all-lateral (AL) entry retrograde nailing. This study compares surgical outcomes, radiographic outcomes, and complication rates between these 2 techniques. METHODS: A retrospective review of a consecutive series of patients treated by retrograde, dual FIMN of femur fractures was performed from 2005 to 2012. Demographics and operative data were recorded. Radiographs were analyzed for fracture pattern, fracture location, percent canal fill by the nails, as well as shortening and angulation at the time of osseous union. Rates of symptomatic implants and their removal were noted. Data were compared between patients treated with medial and lateral entry (ML group) nailing and those treated with all-lateral entry (AL group) nailing using the Student t test and correlation statistics. RESULTS: Of the 244 children with femoral shaft fractures treated with retrograde FIMN using Ender stainless steel nails, 156 were in the ML group and 88 were in the AL group. There were no statistical differences in sex (74% vs. 82% males), age (8.0 vs. 8.6 y), weight (29.4 vs. 31.1 kg), or fracture pattern between the 2 groups. The average total anesthesia time was less in the AL group (133 vs. 103 min) (P<0.0001). There was no difference between the techniques in shortening (3.9 vs. 3.0 mm), coronal angulation (2.9 vs. 2.6 degrees), or sagittal angulation (3.3 vs. 2.7 degrees) at union. In the AL group, there was a correlation between canal fill and reduced shortening at union. No differences were found in the presence or degree of varus alignment, procurvatum deformity, or recurvatum angulation between the constructs. There were 5 malunions in the AL group and 9 malunions in the ML group (5.7% vs. 5.8%, P=1). The incidence of having a healed femur fracture with >10 degrees of valgus was higher in the AL group (0% vs. 3.4%) (P=0.04). There were no differences between the groups in the rate of symptomatic implant removal or surgical complications. CONCLUSIONS: The AL entry technique for FIMN of pediatric femur fractures is 30 minutes faster without worse final fracture alignment, additional complications, or increased rates of symptomatic implants. When using the AL technique, specific attention should be paid to percentage of canal fill and ensuring that the fracture is not reduced in a valgus position. LEVEL OF EVIDENCE: Level III-therapeutic.

Comparison of Ligament Isometry and Patellofemoral Contact Pressures for Medial Patellofemoral Ligament Reconstruction Techniques in Skeletally Immature Patients.

BACKGROUND: Adult medial patellofemoral ligament (MPFL) reconstruction techniques are not appropriate for the skeletally immature patient given the proximity of the distal femoral physis. Biomechanical consequences of reconstructions aimed at avoiding the physis have not been adequately studied. PURPOSE: To quantify the biomechanical effects of MPFL reconstruction techniques intended for skeletally immature patients. STUDY DESIGN: Controlled laboratory study. METHODS: Four MPFL reconstruction techniques were evaluated using a computationally augmented cadaveric model: (1) Schoettle point: adult-type reconstruction; (2) epiphyseal: socket distal to the femoral physis; (3) adductor sling: graft wrapped around the adductor tendon; (4) adductor transfer: adductor tendon transferred to patella. A custom testing frame was used to cycle 8 knees for each technique from 10° to 110° of flexion. Patellofemoral kinematics were recorded using a motion camera system, contact stresses were recorded using Tekscan pressure sensors, and MPFL length was computed using an inverse kinematics computational model. Change in MPFL length, patellar facet forces, and patellar kinematics were compared using generalized estimating equation modeling. RESULTS: Schoettle point reconstruction was the most isometric, demonstrating isometry from 10° to 100°. The epiphyseal technique was isometric until 60°, after which the graft loosened with increasing flexion. The adductor sling and adductor transfer techniques were significantly more anisometric from 40° to 110°. Both grafts tightened with knee flexion and resulted in significantly more lateral patellar tilt versus the intact state in early flexion and significantly higher contact forces on the medial facet versus the epiphyseal technique in late flexion. CONCLUSION: In this cadaveric simulation, the epiphyseal technique allowed for a more isometric ligament until midflexion, when the patella engaged within the trochlear groove. The adductor sling and adductor transfer grafts became tighter in flexion, resulting in potential loss of motion, pain, graft stretching, and failure. Marginal between-condition differences in patellofemoral contact mechanics and patellar kinematics were observed in late flexion. CLINICAL RELEVANCE: In the skeletally immature patient, using an epiphyseal type MPFL reconstruction with the femoral attachment site distal to the physis results in a more isometric graft compared with techniques with attachment sites proximal to the physis.

A Simple Method of Measuring the Distance From the Schöttle Point to the Medial Distal Femoral Physis With MRI.

BACKGROUND: Medial patellofemoral ligament (MPFL) reconstruction is the treatment of choice for recurrent patellar instability in the skeletally immature patient. Avoiding the open physes during anatomic MPFL reconstruction is a challenge in this population. PURPOSE: To describe a novel method using magnetic resonance imaging (MRI) to determine the distance from the Schöttle point to the medial distal femoral physis among skeletally immature individuals with patellar instability. STUDY DESIGN: Descriptive laboratory study. METHODS: Preoperative MRI scans were analyzed from 34 patients with open distal femoral physes and lateral patellar instability. With the multiplanar reconstruction mode on a picture archiving and communication system (PACS), the location of the Schöttle point was determined according to previously reported distances from the posterior femoral cortical line and the posterior origin of the medial femoral condyle. This location was then extrapolated to the most medial sagittal slice on MRI showing the medial distal femoral physis. The distance was measured from this point to the most distal aspect of the physis. RESULTS: The mean age of the study cohort was 13.6 years (range, 10.6-15.7 years); there were 13 males and 21 females. The mean distance from the medial distal femoral physis to the Schöttle point was 7.27 ± 1.78 mm. The Schöttle point was distal to the medial distal femoral physis in all cases. There was no significant correlation between age and mean distance in either the overall study population (r = 0.046, P = .798) or when stratified by sex (females, P = .629; males, P = .089). The distance between the Schöttle point and the medial distal femoral physis was shorter for females than for males (6.51 vs 7.71 mm, P = .043). After adjustment for age, females on average were 1.31 mm closer to the Schöttle point than were males (B = -1.31, P = .041). CONCLUSION: This technique can be used to determine the distance between the medial distal femoral physis and the Schöttle point. The Schöttle point was distal to the physis in all patients, and it was closer to the physis in skeletally immature females compared with age-matched males. CLINICAL RELEVANCE: The long-term repercussions of improperly placed MPFL reconstruction include recurrent patellar instability, increased patellofemoral contact pressures and overtensioning of the ligament, and possibly patellofemoral arthritis. The current technique can be used preoperatively to determine the appropriate safe distance for drilling a socket distal to the physis.

Return to Sport and Reoperation Rates in Patients Under the Age of 20 After Primary Anterior Cruciate Ligament Reconstruction: Risk Profile Comparing 3 Patient Groups Predicated Upon Skeletal Age.

BACKGROUND: With sports specialization and level of competition on the rise, anterior cruciate ligament reconstruction (ACLR) in athletes under the age of 20 has increased significantly in recent years. Reports have demonstrated that the revision ACLR rate is higher and return to sport (RTS) rate is lower in this population. PURPOSE: To evaluate the 2-year clinical outcomes of 3 cohorts of primary ACLR in pediatric and adolescent athletes under the age of 20 based on skeletal age with a focus on RTS and the incidence of second surgery. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: This is a prospective evaluation of 324 athletes younger than 20 years of age who underwent ACLR with minimum 2-year follow-up. The surgical technique was selected predicated on skeletal age, which includes the all-epiphyseal technique with hamstring autograft in the youngest cohort in elementary and middle school (group 1), the partial transphyseal and complete transphyseal with hamstring autograft performed for athletes in the middle cohort (group 2), and bone-tendon-bone autograft in the skeletally mature high school athletes (group 3). RESULTS: The mean chronological age of the entire cohort was 15 years (range, 8-19 years) with 55% males. The 3 cohorts included 49 patients (15%) in group 1 (mean age, 12 years), 66 (20%) in group 2 (mean age, 14.3 years), and 209 (65%) in group 3 (mean age, 16.2 years). Group 2 athletes had a significantly higher revision ACLR rate (20%) compared with group 1 (6%; P = .039) and group 3 (6%; P = .001). Similarly, group 2 athletes had significantly lower RTS rates (85%) compared with group 1 (100%) and group 3 (94%). CONCLUSION: The rate of revision ACLR was significantly higher and the RTS rates significantly lower in group 2 compared with groups 1 and 3. This age-related risk profile may be used to counsel athletes and parents preoperatively regarding the expectations of surgery with respect to revision ACLR and RTS rates.

Toward a More Robust Prediction of Pulmonary Embolism in Trauma Patients: A Risk Assessment Model Based on 38,000 Patients.

OBJECTIVES: Pulmonary embolism (PE) is a rare but sometimes fatal complication of trauma. Risk stratification models identify patients at increased risk of PE; however, they are often complex and difficult to use. This research aims to develop a model, based on a large sample of trauma patients, which can be easily and quickly used at the time of admission to predict PE. METHODS: This study used trauma registry data from 38,597 trauma patients. Of these, 239 (0.619%) developed a PE. We targeted demographic and injury data, prehospital information, and data on treatments and events during hospitalization. A multivariate binary logistic regression model was developed to predict the odds of developing a PE during hospitalization. The model was developed using a 50% randomly selected development subsample and then tested for accuracy using the remaining 50% validation sample. RESULTS: We found 7 statistically significant predictors of PE, including (1) age [odds ratio (OR) = 1.01; 95% CI, 1.00-1.02; P = 0.05], (2) obesity (OR = 2.54; 95% CI, 1.29-4.99; P < 0.01), (3) injury from motorcycle accident (OR = 2.01; 95% CI, 1.25-3.22; P < 0.01), (4) arrival by helicopter (OR = 2.91; 95% CI, 1.16-7.27; P = 0.02), (5) emergency department admission pulse rate (OR = 1.01; 95% CI, 1.0-1.02; P = 0.06), (6) admission to intensive care unit (OR = 5.03; 95% CI, 3.12-8.12; P < 0.01), and (7) injury location, including thorax (OR = 1.57; 95% CI, 1.04-2.37; P = 0.03), abdomen (OR = 1.56; 95% CI, 1.04-2.33; P = 0.03), and lower extremity injuries (OR = 2.85; 95% CI, 3.12-8.12; P < 0.01). Our model was able to discriminate between predicted and actual PE events with a receiver operating characteristic area under the curve of 0.87. By identifying the top 25% high-risk patients, we were able to predict 80%-84% of pulmonary emboli. CONCLUSIONS: This knowledge allows us to focus stronger thromboprophylactic efforts on patients at highest risk. This model can be used to rapidly identify trauma patients at high risk for PE. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Improved Survival After Pelvic Fracture: 13-Year Experience at a Single Trauma Center Using a Multidisciplinary Institutional Protocol.

OBJECTIVES: To analyze pelvic fracture mortality rates before and after initiation of a multidisciplinary pelvic fracture protocol. DESIGN: Retrospective database analysis. SETTING: Prospective data from our Level-I National Trauma Registry of The American College of Surgeons (NTRACS) database. PATIENTS/PARTICIPANTS: A total of 1682 trauma patients with pelvic fractures from 2000 to 2013 were compared with a control group of 42,629 without pelvic fractures. INTERVENTION: Initiation of a multidisciplinary institutional protocol to guide the initial management of trauma patients with pelvic fractures. MAIN OUTCOME MEASUREMENTS: Patients were grouped into 3 periods (group 1: 2000-2003, group 2: 2004-2007, group 3: 2008-2013). Multivariate logistic regression analysis was conducted to assess associations between mortality and age, shock (systolic blood pressure less than or equal to 90 mm Hg), head injury (Glasgow Coma Scale less than or equal to 8), Injury Severity Score (ISS), and time period. RESULTS: Unadjusted mortality rates decreased [12.5%-11.0% (P = 0.72)]; however, ISS increased [19.1-22.7 (P < 0.01)]. Age, shock, head injury, increasing ISS, and earlier period were significantly associated with mortality. Adjusted mortality decreased over time [odds ratio for 2000-2003 vs. 2008-2013: 2.05, 95% confidence interval = (1.26, 3.33) and odds ratio for 2004-2007 vs. 2008-2013: 1.71, 95% confidence interval = (1.09, 2.67)]. From 2000 to 2003, an unstable fracture pattern in the healthiest cohort significantly increased mortality compared with the stable fracture pattern cohort (8.6% and 0.0%, P < 0.01). In subsequent intervals, there was no statistically significant association between stable versus unstable fracture patterns and mortality. CONCLUSIONS: Adjusted pelvic fracture mortality rates have significantly decreased over time. In the healthiest patients with unstable pelvic fractures, the mortality rate is now similar to that of patients with stable fracture patterns. With sustained institutional effort to address pelvic fractures, mortality rates can be diminished. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Lack of Acute Hand Care in the Southwest United States.

OBJECTIVES: To describe the epidemiology of acute hand injuries and hand infections and to describe the factors associated with the transfer of these patients to a level 1 trauma center. In addition, we sought to understand management before transfer. DESIGN: Retrospective review of patients with hand trauma or hand infection transferred to our level 1 trauma center from May 2009 to August 2011. We also identified hospitals with emergency departments (EDs) in our region and surveyed ED providers in these hospitals with regard to acute hand care. SETTING: A level 1 trauma center in the United States. PATIENTS: Four hundred sixty consecutive transfers for acute hand care. RESULTS: The average patient age was 38. Most were male (84%), uninsured (51%), and from another county (59%). The average distance of transfer was 51 miles, and 80% were transferred by ground ambulance. The most common reasons for transfer were amputations (24%), infections (21%), lacerations (17%), and fractures/dislocations (16%). Of the 345 hospitals with an ED surveyed, 71% never had hand surgery coverage. CONCLUSIONS: Patients transferred for acute hand care were young and male, and traveled an average 51 miles to get to our center. More than half of these patients were treated and discharged from our ED. This indicates that a majority may have been managed in a clinic setting. Most EDs in our region do not have a hand surgeon available. Most emergency physicians surveyed had received little training in management of acute hand injuries and hand infections. Further research is needed to identify methods to remove barriers to provision of care for patients with hand trauma. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Lengthening in Congenital Femoral Deficiency: A Comparison of Circular External Fixation and a Motorized Intramedullary Nail.

BACKGROUND: Circular external fixation for limb-lengthening is associated with frequent and numerous complications. Intramedullary lengthening devices represent a potential advance in limb-lengthening. The purpose of this study was to compare the outcomes of femoral lengthening in pediatric patients treated by either circular external fixation or a motorized intramedullary nail. METHODS: All patients with a diagnosis of congenital femoral deficiency who had undergone femoral lengthening with either circular external fixation or a motorized intramedullary nail were identified. The motorized intramedullary nail (FITBONE) was used with approval of the U.S. Food and Drug Administration on an individual compassionate-use basis. RESULTS: Fourteen skeletally mature patients underwent fourteen femoral lengthening sessions using circular external fixation, and thirteen patients underwent fifteen lengthening sessions using the motorized nail. The amount lengthened was similar, with a mean of 4.8 cm (range, 1.0 to 7.4 cm) in the circular fixation group and 4.4 cm (range, 1.5 to 7.0 cm) in the motorized nail group. Complications occurred in all lengthening sessions in all fourteen patients managed with the circular external fixation and in 73% of fifteen lengthening sessions in the thirteen patients managed with the motorized nail. The circular external fixation group averaged 2.36 complications per lengthening session compared with 1.2 per session in the motorized nail group. Twenty-nine percent of the circular fixation group failed to achieve a lengthening goal of at least 4 cm compared with 27% of the motorized nail group who failed to reach the goal. Eight patients had undergone eleven femoral lengthening sessions with circular external fixation prior to undergoing ten lengthening sessions by motorized nail. These patients had a comparable rate of complications with both types of lengthening, but the total number of complications averaged 2.6 per lengthening session with circular external fixation compared with 1.6 per lengthening session with the motorized nail. CONCLUSIONS: A decreased number of complications was noted with use of a motorized intramedullary nail compared with circular external fixation in pediatric patients undergoing femoral lengthening for congenital femoral deficiency. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.