Faculty Bibliography
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Feasibility of three-dimensional MRI of proximal femur microarchitecture at 3 tesla using 26 receive elements without and with parallel imaging
PURPOSE: High-resolution imaging of deeper anatomy such as the hip is challenging due to low signal-to-noise ratio (SNR), necessitating long scan times. Multi-element coils can increase SNR and reduce scan time through parallel imaging (PI). We assessed the feasibility of using a 26-element receive coil setup to perform 3 Tesla (T) MRI of proximal femur microarchitecture without and with PI. MATERIALS AND METHODS: This study had institutional review board approval. We scanned 13 subjects on a 3T scanner using 26 receive-elements and a three-dimensional fast low-angle shot (FLASH) sequence without and with PI (acceleration factors [AF] 2, 3, 4). We assessed SNR, depiction of individual trabeculae, PI performance (1/g-factor), and image quality with PI (1 = nonvisualization to 5 = excellent). RESULTS: SNR maps demonstrate higher SNR for the 26-element setup compared with a 12-element setup for hip MRI. Without PI, individual proximal femur trabeculae were well-depicted, including microarchitectural deterioration in osteoporotic subjects. With PI, 1/g values for the 26-element/12-element receive-setup were 0.71/0.45, 0.56/0.25, and 0.44/0.08 at AF2, AF3, and AF4, respectively. Image quality was: AF1, excellent (4.8 +/- 0.4); AF2, good (4.2 +/- 1.0); AF3, average (3.3 +/- 1.0); AF4, nonvisualization (1.4 +/- 0.9). CONCLUSION: A 26-element receive-setup permits 3T MRI of proximal femur microarchitecture with good image quality up to PI AF2. J. Magn. Reson. Imaging 2014;40:229-238. (c) 2013 Wiley Periodicals, Inc.
PMCID:4004721
PMID: 24711013
ISSN: 1053-1807
CID: 1042112
Hot topics in biomechanically directed fracture fixation
The evolution of locking plates and modern nail constructs provides the orthopaedic trauma surgeon with a myriad of options with regard to implant selection for common fractures. There is a significant amount of biomechanical literature comparing modern constructs with those conventionally used. A basic understanding of this literature is required to make informed decisions with regard to implant selection in the management of these injuries. This article reviews the most recent biomechanical literature regarding implant selection and application for a variety of commonly treated injuries, including fractures of the clavicle, proximal humerus, distal humerus, intertrochanteric hip region, distal femur, and bicondylar tibial plateau.
PMID: 24464098
ISSN: 1531-2291
CID: 991942
Scapula fractures: interobserver reliability of classification and treatment
OBJECTIVES: There is substantial variation in the classification and management of scapula fractures. The first purpose of this study was to analyze the interobserver reliability of the OTA/AO classification and the New International Classification for Scapula Fractures. The second purpose was to assess the proportion of agreement among orthopaedic surgeons on operative or nonoperative treatment. DESIGN: Web-based reliability study. SETTING: Independent orthopaedic surgeons from several countries were invited to classify scapular fractures in an online survey. PARTICIPANTS: One hundred three orthopaedic surgeons evaluated 35 movies of three-dimensional computerized tomography reconstruction of selected scapular fractures, representing a full spectrum of fracture patterns. MAIN OUTCOME MEASUREMENTS: Fleiss kappa (kappa) was used to assess the reliability of agreement between the surgeons. RESULTS: The overall agreement on the OTA/AO classification was moderate for the types (A, B, and C, kappa = 0.54) with a 71% proportion of rater agreement (PA) and for the 9 groups (A1 to C3, kappa = 0.47) with a 57% PA. For the New International Classification, the agreement about the intraarticular extension of the fracture (Fossa (F), kappa = 0.79) was substantial and the agreement about a fractured body (Body (B), kappa = 0.57) or process was moderate (Process (P), kappa = 0.53); however, PAs were more than 81%. The agreement on the treatment recommendation was moderate (kappa = 0.57) with a 73% PA. CONCLUSIONS: The New International Classification was more reliable. Body and process fractures generated more disagreement than intraarticular fractures and need further clear definitions.
PMID: 23629469
ISSN: 1531-2291
CID: 991952
Finite Element Analysis Applied to 3-T MR Imaging of Proximal Femur Microarchitecture: Lower Bone Strength in Patients with Fragility Fractures Compared with Control Subjects
Purpose To determine the feasibility of using finite element analysis applied to 3-T magnetic resonance (MR) images of proximal femur microarchitecture for detection of lower bone strength in subjects with fragility fractures compared with control subjects without fractures. Materials and Methods This prospective study was institutional review board approved and HIPAA compliant. Written informed consent was obtained. Postmenopausal women with (n = 22) and without (n = 22) fragility fractures were matched for age and body mass index. All subjects underwent standard dual-energy x-ray absorptiometry. Images of proximal femur microarchitecture were obtained by using a high-spatial-resolution three-dimensional fast low-angle shot sequence at 3 T. Finite element analysis was applied to compute elastic modulus as a measure of strength in the femoral head and neck, Ward triangle, greater trochanter, and intertrochanteric region. The Mann-Whitney test was used to compare bone mineral density T scores and elastic moduli between the groups. The relationship (R2) between elastic moduli and bone mineral density T scores was assessed. Results Patients with fractures showed lower elastic modulus than did control subjects in all proximal femur regions (femoral head, 8.51-8.73 GPa vs 9.32-9.67 GPa; P = .04; femoral neck, 3.11-3.72 GPa vs 4.39-4.82 GPa; P = .04; Ward triangle, 1.85-2.21 GPa vs 3.98-4.13 GPa; P = .04; intertrochanteric region, 1.62-2.18 GPa vs 3.86-4.47 GPa; P = .006-.007; greater trochanter, 0.65-1.21 GPa vs 1.96-2.62 GPa; P = .01-.02), but no differences in bone mineral density T scores. There were weak relationships between elastic moduli and bone mineral density T scores in patients with fractures (R2 = 0.25-0.31, P = .02-.04), but not in control subjects. Conclusion Finite element analysis applied to high-spatial-resolution 3-T MR images of proximal femur microarchitecture can allow detection of lower elastic modulus, a marker of bone strength, in subjects with fragility fractures compared with control subjects. MR assessment of proximal femur strength may provide information about bone quality that is not provided by dual-energy x-ray absorptiometry. (c) RSNA, 2014.
PMCID:4263634
PMID: 24689884
ISSN: 0033-8419
CID: 895822
Do elderly patients fare worse following operative treatment of distal femur fractures using modern techniques?
BACKGROUND: The purpose of this study was to compare the functional outcomes and quality of life of older and younger patients with similarly treated distal femur fractures. METHODS: We conducted an assessment of 57 patients who sustained distal femur fractures (Orthopaedic Trauma Association Type 33B, C) and underwent surgical treatment at our academic medical center. Patients were divided into 2 groups for analysis: an elderly cohort of patients aged 65 or older and a comparison cohort of patients younger than age of 65. A retrospective review of demographics, preoperative ambulatory status, radiographic data, and physical examination data was collected from the medical records. Follow-up functional data were collected via telephone at a mean of 2.5 years (range 6 months-8 years) using a Short Musculoskeletal Functional Assessment (SMFA). All patients underwent standard operative treatment of either nail or plate fixation. RESULTS: There was no statistical difference in gender, fracture type, surgical technique, surgeon, or institution where the surgery was performed. The percentage of patients with healed fractures at 6-months follow-up was not significantly different between the cohorts. The elderly cohort had slightly worse knee range of motion at 3, 6, and 12 months postoperatively but there was not a statistically significant difference between the groups. The SMFA Daily Activity, Functional, and Bother indices were significantly worse in the older cohort (P < .01, P = .01, P = .02, respectively). However, there was no significant difference in the SMFA Emotional or Mobility indices. CONCLUSION: Despite lower quality of life and functional scores, this study suggests that relatively good clinical outcomes can be achieved with surgical fixation of distal femoral fractures in the elderly patients. Age should not be used as a determinate in deciding against operative treatment of distal femur fractures in the elderly patients.
PMCID:3962055
PMID: 24660097
ISSN: 2151-4585
CID: 897232
Symptomatic atypical femoral fractures are related to underlying hip geometry
The benefits of bisphosphonates are well documented, but prolonged use has been associated with atypical femur fractures. Radiographic markers for fracture predisposition could potentially aid in safer medication use. In this case-control designed study, we compared hip radiographic parameters and the demographic characteristics of chronic bisphosphonate users who sustained an atypical femoral fracture with a group of chronic bisphosphonate users who did not sustain an atypical femur fracture and also a group who sustained an intertrochanteric hip fracture. Radiographic parameters included were neck-shaft angle (NSA), hip-axis length (HAL) and center-edge angle (CE). Multivariate regression was used to evaluate the relationship between radiographic measures and femur fracture. Receiver-operating characteristic analysis determined cut-off points for neck-shaft angle and risk of atypical femur fracture. Ultimately, pre-fracture radiographs of 53 bisphosphonate users who developed atypical fracture were compared with 43 asymptomatic chronic bisphosphonate users and 64 intertrochanteric fracture patients. Duration of bisphosphonate use did not statistically differ between users sustaining atypical fracture and those without fracture (7.9 [+/-3.5] vs. 7.7 [+/-3.3] years, p=0.7). Bisphosphonate users who fractured had acute/varus pre-fracture neck-shaft angles (p<0.001), shorter hip-axis length (p<0.01), and narrower center-edge angles (p<0.01). Regression analysis revealed associations between neck-shaft angle (OR=0.89 [95% CI=0.81-0.97; p=0.01), center edge angle (OR=0.89 [95% CI=0.80-0.99]; p=0.03), and BMI (OR=1.15 [95% CI=1.02-1.31; p=0.03) with fracture development. ROC curve analysis (AUC=0.67 [95% CI=0.56-0.79]) determined that a cut-off point for neck-shaft angle <128.3 degrees yielded 69% sensitivity and 63% specificity for development of atypical femoral fracture. Ultimately, an acute/varus angle of the femoral neck, high BMI, and narrow center-edge angle were associated with development of atypical femur fracture in long-term bisphosphonate users. Patients on long-term bisphosphonates should be regularly radiographically evaluated in order to assess for potential risk of atypical fracture.
PMID: 24565751
ISSN: 1873-2763
CID: 881722
The association of education level on outcome after distal radius fracture
BACKGROUND: Socioeconomic factors have been found to be predictors of outcome for other ailments. The purpose of this study was to evaluate the association of patient education level on pain and disability after distal radius fracture. METHODS: A series of patients with distal radius fractures (n = 335) were enrolled into a prospective research registry. Standard demographic information was obtained from patients, including a five-value categorical education variable. After treatment with closed reduction, external fixation, or internal fixation patients were evaluated for pain, function (Disability of the Arm, Shoulder, and Hand score [DASH]), range of motion (ROM), and grip strength at standard intervals until 12 months post-injury. A series of linear mixed effects models were developed to evaluate the relationship between time from injury and education level with each of the outcomes measured. RESULTS: Complete demographic and 12-month follow-up data were available on 227 patients (75 %). There were neither group differences in mode of injury, severity, nor treatment modality after stratification by education level. Mixed effects model analyses revealed a significant linear association between level of education and measured outcomes at each follow-up point. Overall, each increase in education level demonstrated a doubling of improvement in pain, ROM, grip strength, and DASH score. CONCLUSIONS: Outcome of distal radius fracture depends on acute care and follow-up rehabilitation; however, patient-related factors indicative of socioeconomic status are becoming increasingly relevant as predictors of outcome and should be considered by the orthopaedist.
PMCID:3928390
PMID: 24570641
ISSN: 1558-9447
CID: 820742
Low velocity gunshot wounds result in significant contamination regardless of ballistic characteristics
Controversy exists among the orthopedic community regarding the treatment of gunshot injuries. No consistent treatment algorithm exists for treatment of low energy gunshot wound (GSW) trauma. The purpose of this study was to critically examine the wound contamination following low velocity GSW based upon bullet caliber and clothing fiber type found within the injury track. Four types of handguns were fired at ballistic gel from a 10-foot distance. Various clothing materials were applied (denim, cotton, polyester, and wool) circumferentially around the tissue agar in a loose manor. A total of 32 specimens were examined. Each caliber handgun was fired a minimum of 5 times into a gel. Regardless of bullet caliber there was gross contamination of the entire bullet track in 100% of specimens in all scenarios and for all fiber types. Furthermore, as would be expected, the degree of contamination appeared to increase as the size of the bullet increased. Low velocity GSWs result in significant contamination regardless of bullet caliber and jacket type. Based upon our results further investigation of low velocity GSW tracks is warranted. Further clinical investigation should focus on the degree to which debridement should be undertaken.
PMID: 24490188
ISSN: 1078-4519
CID: 800122
The effect of two different trochanteric nail lag-screw designs on fixation stability of four-part intertrochanteric fractures: a clinical and biomechanical study
OBJECTIVES: To compare lag-screw sliding characteristics and fixation stability of two cephalomedullary nails (CMN) with different lag-screw designs (solid and telescopic), we conducted a biomechanical study and an analysis of clinical results. METHODS: Six pairs of cadaver femurs with simulated intertrochanteric fractures were randomly assigned to one of two CMN fixations. Femur constructs were statically then cyclically loaded on an MTS machine. Lag-screw sliding and inferior and lateral femoral head displacements were measured, following which failure strength of the construct was determined. Forty-five patients with intertrochanteric fractures treated with these CMN were identified. Medical records and radiographs were reviewed and analyzed using Fisher's exact test and Student's t test to determine lag-screw sliding. RESULTS: No difference was seen with cycling in inferior femoral head displacement between the two screw designs. The solid screw had an average inferior head displacement of 1.75 mm compared with 1.59 mm for the telescoping screw (p = 0.772). The solid lag screws slid an average of 2.79 mm lateral from the nail, whereas the telescoping screws slid an average of 0.27 mm (p = 0.003). In our clinical review, the average lateral sliding of the telescoping screw was 0.5 mm and of the solid screw was 3.7 mm (p < 0.001). Despite differences in lateral sliding, there were no reoperations for prominent or painful hardware in either group. CONCLUSIONS: Both designs are acceptable devices for stabilization of intertrochanteric fractures. Clinical and biomechanical data demonstrate greater lateral sliding in the solid lag-screw group, making for greater potential for lateral-sided hip pain in CMNs with solid lag screws as opposed to telescoping lag screws.
PMID: 24248549
ISSN: 0949-2658
CID: 777992
Atypical Femur Fractures
Osteoporosis (OP) results from an imbalance between bone production and absorption that results in decreased bone mass as well as microstructural deterioration of the bone trabeculae, leading to diminished bone quality and fragility fractures. It is synonymous with decreased bone strength and affects millions of people worldwide.The most commonly prescribed drugs for the treatment of OP are the bisphosphonates (BPs). Long-term BP use may be associated with stress fractures of the subtrochanteric and shaft regions of the femur known as atypical femur fractures (AFFs). Although AFFs can be devastating, BPs have decreased the number of low-energy hip fractures as well as the number of vertebral and non-vertebral fractures that occur each year.Many trials and population-based studies have assessed the association between AFF and BP, and several studies have attempted to establish AFF's true incidence. We will summarize a few of the major studies and discuss their strengths and limitations. The findings of an association between BPs and AFFs have been variable and may reflect sample selection and measurement bias.AFFs are uncommon; the increase in risk associated with BP use is very small and does not outweigh the benefit of fracture prevention in patients with OP. Evidence for the efficacy of BPs for the prevention of fractures in postmenopausal women with OP is very strong, and the current clinical practice of using BPs as first-line therapy for these patients should be continued. Further information is required to determine the appropriate duration and time of discontinuation of BP therapy.
PMID: 24476604
ISSN: 0890-5339
CID: 779582
