The effect of gadolinium-based intravenous contrast in the initial characterization of musculoskeletal soft tissue tumors.

OBJECTIVE: To determine if gadolinium-based contrast agents increase the sensitivity, specificity or reader confidence of malignant potential in musculoskeletal soft tissue tumors. METHODS: Pre- and post-contrast MRI studies from 87 patients were read by three independent radiologists of different experience. Readers noted malignant potential and confidence in their diagnosis based on pre-contrast and post-contrast MRI studies. Statistical models assessed for agreement between MRI reader diagnosis and pathologic results as well as analyzing effects of contrast on reader confidence. Inter- and intra-observer variabilities of malignant potential were also calculated. RESULTS: 87 patients (48 benign and 39 malignant; mean [± SD] age 51 ± 17.9 and 57.1 ± 17.1, respectively) were evaluated. For all readers, pre-contrast and post-contrast sensitivities were 68.1 % and 70.6 % while pre-contrast and post-contrast specificities were 84.6 % and 83.8 %, respectively without significant change (p=0.88). There was not a significant association with the use of contrast and prediction of malignant potential with or without the resident reader (p=0.65 and p=0.82). Use of contrast was significantly associated with higher levels of reader confidence (p=0.02) for all readers. Inter- and intra-observer variabilities were in good agreement (W = 0.77 and 0.70). CONCLUSION: The addition of a post-contrast sequence increased reader confidence in their diagnosis without a corresponding significant increase in accurate prediction of malignant potential.

Combined Lateral Osseolabral Coverage Is Normal in Hips With Acetabular Dysplasia.

PURPOSE: To compare the lateral osseolabral coverage between groups of patients with different degrees of acetabular bony coverage using a magnetic resonance imaging parameter known as the combined lateral center-edge angle (cLCEA). METHODS: The cLCEA was measured among a consecutive series of patients presenting to a dedicated hip preservation surgeon with a magnetic resonance imaging scan. The cLCEA was measured using a coronal T1 or proton density image and was defined as the angle subtended by (1) a line through the center of the femoral head and orthogonal to the transverse line passing through the teardrops of both hips and (2) an oblique line drawn from the center of the femoral head to the free edge of the lateral acetabular labrum. The average difference between the lateral center-edge angle (LCEA) and the cLCEA was calculated and compared between groups based on acetabular bony coverage: dysplasia (LCEA <20°), borderline dysplasia (LCEA 20°-24.9°), normal coverage (LCEA 25°-39.9°), and overcoverage (LCEA ≥40°). RESULTS: In total, 341 patients (386 hips) were included. There were no significant differences in cLCEA between hips with normal acetabular coverage and dysplasia (P = .10) or borderline dysplasia (P = .46). Despite the large difference in mean LCEA between dysplasia (14.8° ± 3.9°) and acetabular overcoverage (43.1° ± 2.8°), the mean cLCEA values exhibited only a modest difference (44.7° ± 4.9° vs 52.7° ± 4.5°, respectively). Concordantly, hips with dysplasia exhibited the largest difference between mean LCEA and cLCEA (delta = 29.9° ± 4.7°) and hips with acetabular overcoverage had the smallest difference between measures (9.6° ± 5.2°). CONCLUSIONS: With decreasing acetabular bony coverage, there is increasing labral size such that the total osseolabral coverage, measured by the combined LCEA, remains equivalent between hips with normal acetabular coverage versus dysplasia. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Gymnast's wrist in a 12-year-old female with MRI correlation.

We describe a case of chronic overuse injury of the distal radial physis (gymnast's wrist). While the radiographic appearance of this entity has been reported, there are limited studies highlighting the MR appearance of this entity. This lesion is being seen with increasing frequency in young, elite gymnasts. If this injury goes unrecognized, there is potential for abnormal osseous development, with premature physeal fusion, abnormal joint inclination and even Madelung deformity.

Percutaneous renal artery revascularization after prolonged ischemia secondary to blunt trauma: pooled cohort analysis.

PURPOSE: We aimed to identify factors related to technical and clinical success of percutaneous revascularization for blunt renal arterial trauma. METHODS: All cases of percutaneous revascularization for blunt renal arterial trauma were searched in the available literature. We included a case of iatrogenic renal artery occlusion at our institution treated by percutaneous stenting 20 hours after injury. A pooled cohort analysis of percutaneous revascularization for blunt renal artery injury was then performed to analyze factors related to technical and clinical success. Clinical failure was defined as development of new hypertension, serum creatinine rise, or significant asymmetry in split renal function. RESULTS: A total of 53 cases have been reported, and 54 cases were analyzed including our case. Median follow-up was 6 months. Technical success was 88.9% and clinical success was 75%. Of 12 treatment failures (25%), 66.7% occurred during the first postprocedure month. Time from injury to revascularization was not a predictor of clinical success (OR=1.00, P = 0.681). Renal artery occlusion was significantly associated with clinical failure (OR=7.50, P = 0.017) and postintervention antiplatelet therapy was significantly associated with treatment success (OR=0.16, P = 0.043). At 37-month follow-up, the stented renal artery in our case remained patent and the patient was normotensive with preserved glomerular filtration rate. CONCLUSION: Percutaneous revascularization for blunt renal arterial injury resulted in relatively high technical and clinical success. Time-to-revascularization was independent of successful outcomes. Clinical success was significantly associated with a patent renal artery at the time of intervention and with postprocedure antiplatelet therapy.

The Iliofemoral Line: A Radiographic Sign of Acetabular Dysplasia in the Adult Hip.

BACKGROUND: Several radiographic parameters utilized for the diagnosis of acetabular dysplasia in adults suffer from poor reproducibility and reliability. PURPOSE: To define and validate a novel radiographic parameter (the iliofemoral line [IFL]) for the detection of frank and borderline hip dysplasia and to compare the sensitivity and specificity of this radiographic marker to those of previously validated qualitative parameters. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: A consecutive cohort of 222 adult patients (436 hips) undergoing hip preservation surgery was included. The IFL, which extends from the lateral femoral neck through the inner cortical lip of the iliac crest, intersects the femoral head in cases of dysplasia. Percent medialization of the IFL was defined as the horizontal distance of the exposed femoral head lateral to the IFL, relative to the horizontal femoral head width at the center of the femoral head. RESULTS: Percent medialization of the IFL was strongly correlated to the lateral center edge angle ( P < .0001). Values of percent medialization ranging from 15% to 22% predicted the presence of borderline hip dysplasia with a sensitivity of 62% and specificity of 89%, while values exceeding 22% predicted the presence of frank acetabular dysplasia with a sensitivity of 77% and specificity of 94%. By comparison, abnormality of the Shenton line demonstrated a sensitivity of 3.7% and specificity of 97% for the detection of borderline dysplasia and a sensitivity of 16% and specificity of 99% for the detection of frank acetabular dysplasia. Compared with the Shenton line, percent medialization of the IFL was significantly more sensitive for the detection of both borderline and frank acetabular dysplasia (both P < .0001). The intraobserver and interobserver reproducibility of the horizontal difference outside the IFL were 0.99 and 0.96, respectively. CONCLUSION: Percent medialization of the IFL is a reliable and accurate radiographic marker of frank acetabular dysplasia and, to a lesser extent, borderline dysplasia. The use of this radiographic parameter as an additional tool may enable the earlier detection of borderline and frank hip dysplasia in young adults presenting with hip pain.

Lateral Acetabular Coverage Predicts the Size of the Hip Labrum.

BACKGROUND: Bony morphological abnormalities of the hip joint are often accompanied by adaptive soft tissue changes. These adaptive changes, if better understood and characterized, may serve to inform clinical decision making. PURPOSE: To investigate the correlation between the size of the hip labrum and lateral acetabular coverage in patients at our hip preservation clinic. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A cohort of 236 patients seen at a dedicated hip preservation service between June 2013 and June 2015 were retrospectively analyzed. Patients were grouped according to the degree of acetabular coverage, as measured by the lateral center-edge angle (LCEA): normal acetabular coverage (25°-39.9°), acetabular overcoverage (≥40°), borderline dysplasia (20°-24.9°), and frank dysplasia (<20°). Preoperative magnetic resonance imaging was utilized to measure the length of the labrum at 3 locations: laterally, anteriorly, and anteroinferiorly. RESULTS: Frankly dysplastic and borderline dysplastic hips exhibited larger values of labral length at all locations when compared with hips with normal acetabular coverage (P < .001) or acetabular overcoverage (P < .001). Interestingly, mean labral length values in frank dysplasia were statistically similar to corresponding measurements in borderline dysplasia. In hips with frank dysplasia, borderline dysplasia, or normal acetabular coverage, labral length was consistently greatest at the lateral labrum and correspondingly lowest at the anteroinferior labrum (P < .001). In hips with acetabular overcoverage, labral length did not vary significantly between the lateral, anterior, and anteroinferior locations. Multivariate analyses confirmed LCEA to be the strongest predictor of labral length, irrespective of measurement location. CONCLUSION: Patients with borderline dysplasia and frank dysplasia exhibited increased values of labral length in the weightbearing zone, potentially indicating a compensatory reaction to the lack of bony coverage. Labral length may serve as an instability marker and inform clinical decision making for patients with borderline dysplasia.

Lateral acetabular coverage as a predictor of femoroacetabular cartilage thickness.

To investigate the correlation between femoroacetabular cartilage thickness and lateral acetabular coverage in patients undergoing hip arthroscopy for a variety of indications. Articular cartilage at the hip is hypothesized to undergo adaptive change secondary to unique patterns of pathomechanical loading which results in a direct relationship between acetabular coverage and femoroacetabular cartilage thickness. A cohort of 252 patients presenting to our dedicated hip preservation service between June 2013 and June 2015 were retrospectively analysed. Preoperative radiographs and MRI studies were obtained for all symptomatic hips and classified according to radiographic lateral center edge angle (LCEA) as follows: normal acetabular coverage (25-40°), acetabular overcoverage (≥40°), borderline dysplasia (20-24.9°) and frank dysplasia (<20°). Femoroacetabular cartilage thickness was measured on a preoperative MRI-scan at the fovea, middle sourcil, and lateral sourcil. In all groups, cartilage thickness was maximized at the lateral sourcil relative to the middle sourcil or fovea (P < 0.001). Furthermore, articular cartilage thickness was significantly increased when comparing one group to successive groups with diminished lateral acetabular coverage. Indeed, multivariate analyses confirmed LCEA to be the strongest determinant of femoroacetabular cartilage thickness compared with age, gender, body-mass index or presence of cam/pincer lesions. Patients with borderline and frank dysplasia exhibit increased values of femoroacetabular cartilage thickness in the weight-bearing zone, potentially indicating a compensatory reaction to the lack of bony coverage. Articular cartilage thickness may serve as an instability marker and inform clinical decision-making for patients with borderline dysplasia.

Real-time magnetic resonance imaging (MRI) during active wrist motion--initial observations.

BACKGROUND: Non-invasive imaging techniques such as magnetic resonance imaging (MRI) provide the ability to evaluate the complex anatomy of bone and soft tissues of the wrist without the use of ionizing radiation. Dynamic instability of wrist--occurring during joint motion--is a complex condition that has assumed increased importance in musculoskeletal medicine. The objective of this study was to develop an MRI protocol for evaluating the wrist during continuous active motion, to show that dynamic imaging of the wrist is realizable, and to demonstrate that the resulting anatomical images enable the measurement of metrics commonly evaluated for dynamic wrist instability. METHODS: A 3-Tesla "active-MRI" protocol was developed using a bSSFP sequence with 475 ms temporal resolution for continuous imaging of the moving wrist. Fifteen wrists of 10 asymptomatic volunteers were scanned during active supination/pronation, radial/ulnar deviation, "clenched-fist", and volarflexion/dorsiflexion maneuvers. Two physicians evaluated distal radioulnar joint (DRUJ) congruity, extensor carpi ulnaris (ECU) tendon translation, the scapholunate (SL) interval, and the SL, radiolunate (RL) and capitolunate (CL) angles from the resulting images. RESULTS: The mean DRUJ subluxation ratio was 0.04 in supination, 0.10 in neutral, and 0.14 in pronation. The ECU tendon was subluxated or translated out of its groove in 3 wrists in pronation, 9 wrists in neutral, and 11 wrists in supination. The mean SL interval was 1.43 mm for neutral, ulnar deviation, radial deviation positions, and increased to 1.64 mm during the clenched-fist maneuver. Measurement of SL, RL and CL angles in neutral and dorsiflexion was also accomplished. CONCLUSION: This study demonstrates the initial performance of active-MRI, which may be useful in the investigation of dynamic wrist instability in vivo.

Derivation of a clinical risk score for traumatic orbital fracture.

BACKGROUND: Given that orbital fractures are found in only one of every eight patients receiving computed tomography for acute orbital trauma, we sought to prospectively identify clinical predictors of orbital fracture that may obviate the need for exposing low-risk patients to ionizing radiation. METHODS: Prospective cohort study conducted from July 2007 through October 2009 at two urban emergency departments. Consecutive patients undergoing computed tomography for acute blunt orbital trauma were evaluated on 15 clinical findings before imaging. The primary outcome of interest was presence of any acute orbital fracture. The secondary outcome was a fracture requiring emergent operative intervention. Multivariable logistic regression analysis with multiple imputation was used to derive a predictive risk score. RESULTS: A total of 2,262 patients with acute orbital trauma were enrolled. Median age was 38 years with male predominance (68.3%). Acute orbital fractures were found in 360 patients (15.9%). The derived risk score included orbital rim tenderness, periorbital emphysema, subconjunctival hemorrhage, pain with extraocular movement, impaired extraocular movement, and epistaxis. Across 10 multiply imputed data sets, a mean of 660 patients (29.2%) lacked all six equally weighted predictors, of which 6.3% (95% confidence interval, 4.3-8.2) experienced an acute orbital fracture and only 0.5% (95% confidence interval, 0.0-1.0) required emergent operative intervention. CONCLUSION: Six clinical predictors identify patients with blunt orbital trauma at increased risk for acute orbital fracture. A risk score of 0 identifies patients at very low risk for emergent operative intervention. Multicenter studies are needed to validate these findings and derive a clinical decision instrument to reduce orbital imaging without compromising patient safety. LEVEL OF EVIDENCE: Diagnostic study, level II.

The epidemiology of mountain bike park injuries at the Whistler Bike Park, British Columbia (BC), Canada.

OBJECTIVE: To describe the epidemiology of injuries sustained during the 2009 season at Whistler Mountain Bike Park. METHODS: A retrospective chart review was performed of injured bike park cyclists presenting to the Whistler Health Clinic between May 16 and October 12, 2009. RESULTS: Of 898 cases, 86% were male (median age, 26 years), 68.7% were Canadian, 19.4% required transport by the Whistler Bike Patrol, and 8.4% arrived by emergency medical services. Identification of 1759 specific injury diagnoses was made, including 420 fractures in 382 patients (42.5%). Upper extremity fractures predominated (75.4%), 11.2% had a traumatic brain injury, and 8.5% were transferred to a higher level of care: 7 by helicopter, 62 by ground, and 5 by personal vehicle. Two patients refused transfer. CONCLUSIONS: Mountain bikers incurred many injuries with significant morbidity while riding in the Whistler Mountain Bike Park in 2009. Although exposure information is unavailable, these findings demonstrate serious risks associated with this sport and highlight the need for continued research into appropriate safety equipment and risk avoidance measures.

Upper-limb joint power and its distribution in spinal cord injured wheelchair users: steady-state self-selected speed versus maximal acceleration trials.

OBJECTIVE: To compare upper-limb joint power magnitude and distribution between the shoulder, elbow, and wrist during maximal acceleration (MAC) versus steady-state, self-selected speed (SSS) manual wheelchair propulsion. DESIGN: Cross-sectional biomechanic study. SETTING: Research university and teaching hospital. PARTICIPANTS: Volunteer sample of 13 manual wheelchair users with spinal cord injury below T1. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Propulsive joint power magnitude and fractional distribution among upper-limb joints. RESULTS: Wilcoxon signed-rank testing revealed shoulder power was larger for MAC versus SSS (median peak, 101.5W; interquartile range [IQR], 74.6; median peak, 37.7W; IQR, 22.9; respectively) (P<.01). Elbow and wrist power were unchanged. Peak shoulder power fraction was larger for MAC versus SSS (median peak, 1.055; IQR, .110 vs peak, .870; IQR, .252) (P<.01). Peak elbow power fraction was smaller for MAC versus SSS (median peak, -.012; IQR, .144 vs peak, .146; IQR, .206) (P<.05). Peak wrist power fraction was smaller for MAC versus SSS (median peak, -.058; IQR, .057 vs peak, -.010; IQR, .150) (P<.05). CONCLUSIONS: Power at the shoulder was larger than at other joints. Peak shoulder joint power and power fraction was larger during MAC versus SSS propulsion. Elbow and wrist power fractions were smaller for MAC versus SSS propulsion. Higher joint power, present under MAC, may predispose manual wheelchair users to injury, particularly at the shoulder.