Faculty Bibliography

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.

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.

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.

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.

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.

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.

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.

OBJECTIVES:: The purpose of this study is to characterize the presentation, size, treatment, and complications of pulmonary embolism (PE) in a large series of orthopaedic trauma patients who developed PE after injury. METHODS:: We reviewed the records of orthopaedic trauma patients who developed a PE within 6 months of injury at 9 trauma centers and 2 tertiary care facilities. RESULTS:: There were 312 patients, 186 men and 126 women, avg age 58. Average BMI was 29.6, avg ISS was 18. 17% received anticoagulation prior to injury, and 5% had a prior history of PE. After injury, 87% were placed on prophylactic anticoagulation; 68% with low molecular weight heparin. 53% of patients exhibited shortness of breath or chest pain. Average heart rate and O2 saturation prior to PE diagnosis were 110 and 94, respectively. 39% had abnormal ABG and 30% had abnormal EKG findings. 89% had CTPA for diagnosis. Most clots were segmental (63%), followed by subsegmental (21%), lobar (9%), and central (7%). The most common treatment was unfractionated heparin and Coumadin (25%). Complications of anticoagulation were common: 10% had bleeding at the surgical site. Other complications of anticoagulation included GI bleed, anemia, wound complications, death, and compartment syndrome. PE recurred in 1%. 4% died of PE within 6 months. CONCLUSIONS:: This is the first large data set to evaluate the course of PE in an orthopaedic trauma population. The complications of anticoagulation are significant and were as common in the patients with lower risk clots as those with higher risk clots. LEVEL OF EVIDENCE:: III (retrospective).

BACKGROUND: Prior studies have suggested that Asian patients and women may be more likely to sustain atypical femoral fractures in association with bisphosphonate use. However, they do not account for confounders such as asymptomatic patients who are long-term bisphosphonate users or patients sustaining osteoporotic fractures. QUESTIONS/PURPOSES: The purpose of this study was to determine the differences in sex and racial association with atypical femoral fractures by comparing demographic characteristics of patients who sustained an atypical bisphosphonate-associated fracture with patients on long-term bisphosphonates without fractures and with patients who sustained osteoporotic fractures. METHODS: Three groups from prospective registries were identified: (1) patients with atypical femur fractures associated with long-term bisphosphonate use (BFF) (n = 54); (2) patients on long-term bisphosphonates but with no associated fractures (BNF) (n = 119); and (3) patients with osteoporotic proximal femur fractures not associated with bisphosphonates (PFF) (n = 216). Age, sex, and self-reported race/ethnicity were documented and compared. Multivariate and univariate analyses were done as well as age- and sex-stratified analyses. RESULTS: Age and sex distributions of the BFF and BNF patients were similar. There was a higher percentage of Asian patients in the BFF group (17%) than in the BNF group (3%; p = 0.004) as well as Hispanics (13% versus 3% in BNF; p = 0.011). Patients in the BFF group were younger than those in the PFF group (67.5 versus 78.4 years; p < 0.001) and had fewer males (7% versus 14%; p < 0.001). CONCLUSIONS: These data suggest that Asians are at higher risk for atypical bisphosphonate-associated fractures. We recommend closer followup in Asian patients who are taking bisphosphonates. LEVEL OF EVIDENCE: Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

BACKGROUND: We investigated the radiographic parameters that may predict distal radial ulnar joint (DRUJ) instability in surgically treated radial shaft fractures. In our clinical experience, there are no previously reported radiographic parameters that are universally predictive of DRUJ instability following radial shaft fracture. MATERIALS AND METHODS: Fifty consecutive patients, ages 20-79 years, with unilateral radial shaft fractures and possible associated DRUJ injury were retrospectively identified over a 5-year period. Distance from radial carpal joint (RCJ) to fracture proportional to radial shaft length, ulnar variance, and ulnar styloid fractures were correlated with DRUJ instability after surgical treatment. RESULTS: Twenty patients had persistent DRUJ incongruence/instability following fracture fixation. As a proportion of radial length, the distance from the RCJ to the fracture line did not significantly differ between those with persistent DRUJ instability and those without (p = 0.34). The average initial ulnar variance was 5.5 mm (range 2-12 mm, SD = 3.2) in patients with DRUJ instability and 3.8 mm (range 0-11 mm, SD = 3.5) in patients without. Only 4/20 patients (20 %) with DRUJ instability had normal ulnar variance (-2 to +2 mm) versus 15/30 (50 %) patients without (p = 0.041). CONCLUSION: In the setting of a radial shaft fracture, ulnar variance greater or less than 2 mm was associated with a greater likelihood of DRUJ incongruence/instability following fracture fixation.