Single-Plane 3-Dimensional Isotropic Spin-Echo Magnetic Resonance Imaging Reconstructions of Shoulder Exhibit Superior Correlation to Surgical Findings Than 2-Dimensional Dixon Multiplanar Magnetic Resonance Imaging.

OBJECTIVE: The aim of the study is to evaluate concordance of multiplanar 2-dimensional magnetic resonance imaging (2D-MRI) versus 3D isotropic MRI for rotator cuff and labral tears with the reference standard of arthroscopic surgical findings. METHODS: It was an institutional review board-approved retrospective single-center study of consecutive preoperative patients with isotropic 3D-MRI on 3-Tesla scanners, multiplanar 2D-MRI, and shoulder arthroscopy. Scapular plane-oriented contiguous multiplanar reconstructions of 3D-images were evaluated by 2 experienced fellowship-trained musculoskeletal radiologists. Variables included the following: labral tear presence and rotator-cuff tear Ellman grade, thickness, and width. Sensitivities (Sen) and specificities (Spe) were calculated for binary variables. Mean squared errors (MSE) were calculated for ordinal variables. Lower MSE indicated higher concordance. RESULTS: Seventy-two patients (43 female) with a mean age of 50.75 ± 9.76 years were evaluated. For infraspinatus-tear presence, 3D-MRI showed higher sensitivity (0.96) and specificity (0.68) than 2D-MRI (Sen = 0.85, Spe = 0.32) ( Psen = 0.005, Pspe = 0.002). For subscapularis-tear presence, 3D-MRI showed higher sensitivity (0.94) and specificity (0.73) compared with 2D-MRI (Sen = 0.83, Spe = 0.56) ( Psen = 0.02, Pspe = 0.04). For supraspinatus-tear presence, there was no significant difference between 3D-MRI (Sen =0.96, Spe = 0.67) compared with 2D-MRI (Sen = 0.98, Spe = 0.83) ( Psen = 0.43, Pspe = 0.63). For infraspinatus-tear thickness, 3D-MRI showed lower MSE (0.35) compared with 2D-MRI MSE (0.82) ( P = 0.01). For subscapularis-tear thickness, 3D-MRI had lower MSE (0.31) compared with 2D-MRI MSE (0.51) ( P = 0.007). However, no difference noted for supraspinatus-tear thickness when comparing 3D-MRI MSE (0.39) and 2D-MRI MSE (0.51) ( P = 0.49). For labral-tear presence, 3D-MRI had a lower MSE (0.20) compared with 2D-MRI MSE (0.57) ( P < 0.001). CONCLUSIONS: Three-dimensional MRI of the shoulder is time efficient with a shorter acquisition time and exhibits comparable with superior correlation to surgical findings than 2D-MRI for detection of labral tears and some rotator cuff tears. Three-dimensional MRI may be used in place of traditional 2D-MRI in detection of soft-tissue shoulder injury in centers equipped to do so.

Treatment of Delbet II/III Pediatric Femoral Neck Fractures With Proximal Femoral Locking Plate Versus Cannulated Screws.

INTRODUCTION: Complications following operative treatment of pediatric femoral neck fractures include nonunion, coxa vara, and avascular necrosis (AVN). Proximal femoral locking plates (PFLPs) provide a fixed-angle construct that may reduce the rates of coxa vara, but their use in pediatric femoral neck fractures has not been studied. The purpose of this study was to evaluate rates of union, coxa vara, and AVN in traumatic pediatric femoral neck fractures treated with PFLP or cannulated screws (CS). METHODS: We retrospectively reviewed all traumatic, nonpathologic Delbet II/III femoral neck fractures in patients below 18 years of age treated with PFLP or CS. All cases had ≥6 months of radiographic follow-up to evaluate for osseous union and AVN. Changes in proximal femoral alignment were determined by measuring injured and contralateral femoral neck-shaft angle and articulotrochanteric distance (ATD) between 6 and 12 months postoperatively. RESULTS: Forty-two patients were identified with mean age at surgery of 10.7±2.9 years (range 3.3 to 16.3 years) and mean follow-up of 36±27 months. Sixteen patients (38%) underwent PFLP fixation, whereas 26 patients (62%) underwent CS fixation. When compared with the CS cohort, the PFLP cohort had a greater proportion of males (87.5% vs. 50%, P =0.02) and Delbet III fractures (68.8% vs. 15.4%, P <0.001). There was no difference between PFLP and CS cohorts with respect to rates of union (81% vs. 88%, respectively, P =0.66), AVN (25% vs. 35%, respectively, P =0.73), or secondary surgery (62% vs 62%, P =0.95). There was no significant difference in neck-shaft angle between injured and contralateral hips in those patients treated with PFLP ( P =0.93) or CS ( P =0.16). However, the ATD was significantly decreased in hips treated with CS compared with the contralateral hip (18.4±4.6 vs. 23.3±4.2 mm, P =0.001), with no significant difference in the PFLP group ( P =0.57). CONCLUSIONS: This study suggests that the use of a PFLP in Delbet II/III femoral neck fractures does not appear to significantly increase nonunion rates or AVN and maintains anatomic ATD when compared with screw fixation. LEVEL OF EVIDENCE: Level III-therapeutic study.

Extent of bone marrow edema on dual-energy CT aids in differentiation of acute from post-acute fractures of lower legs.

OBJECTIVES: Bone marrow edema (BME) from dual-energy CT is useful to direct attention to radiographically occult fractures. The aim was to characterize utility of BME of lower extremity (LE) fractures with the hypothesis that stabilized and post-acute fractures exhibit decreased extent and frequency of BME than non-stabilized and acute fractures, respectively. METHODS: An IRB-approved retrospective review of known LE fractures. A total of 141 cases met inclusion criteria, including 82 fractures without splint/cast stabilization, and 59 cases with stabilization. Two readers independently recorded BME, and its multiplicity and area (mm2). A separate reader assessed fracture location, comminution, and chronicity. Wilcoxon rank sum test, multiple regression, intraclass correlation (ICC), kappa statistics, and chi-square tests were used. RESULTS: BME was significantly larger in non-stabilized (859.3 mm2 (420.6-1451.8)) than stabilized fractures (493.5 mm2 (288.8-883.2)), p = .011). Comminuted (p = 0.006), non-stabilized (p = 0.0004), and acute fractures (p = 0.036) were all associated with larger BME area. BME presence had excellent results for both stabilized (Cohen's Kappa = 0.81) and non-stabilized fractures (Cohen's Kappa = 0.84). ICC for BME area showed excellent correlation for both stabilized (ICC = 0.78) and non-stabilized groups (ICC = 0.86). BME multiplicity showed excellent agreement for stabilized (ICC = 0.81) and good agreement for non-stabilized (ICC = 0.67) fractures. Lastly, stabilized cases showed increased multiplicity of BME compared to non-stabilized fractures (p < 0.001). CONCLUSIONS: BME evaluation can assist in differentiation of acute versus post-acute fractures. Extent of BME is reduced with splint/cast stabilization, which may limit its accuracy in detection of lower extremity fractures. KEY POINTS: • Evaluation of bone marrow edema on dual-energy CT aids in differentiation of acute versus post-acute fracture. • Bone marrow edema evaluation is limited in the setting of post-acute or stabilized fractures. • There is decreased frequency and extent of bone marrow edema in post-acute, non-comminuted, and stabilized fractures.

Anterior cruciate ligament foot plate anatomy: 3-dimensional and 2-dimensional MRI evaluation with arthroscopy assessment in a subset of patients.

OBJECTIVES: ACL reconstruction tunnel location is an important predictor for outcomes after surgery. The aim was to establish 3D and 2D MRI radiological measurements for native ACL tibial footprint that can provide information to facilitate pre-operative planning for anatomical graft placement. The measurements were also correlated in a subset of patients on arthroscopy. METHODS: Retrospective evaluation of a consecutive series of knee MRIs with both 2D and 3D MR imaging was performed in 101 patients with 43 men and 66 women and ages 39.5 ± 11.9 years. Two measurements were obtained, tibial to ACL and intermeniscal ligament to ACL (T-ACL) and (IM-ACL), respectively. In a cohort of 18 patients who underwent knee arthroscopy, the T-ACL and IML-ACL distances were also determined by an orthopedic surgeon using a standard scale. ICC, Pearson correlation, and Bland-Altman plot were generated. RESULTS: For readers 1 and 2, the mean differences between 2D and 3D measurements of T-ACL and IM-ACL were 1.17 and 1.03 mm and 0.65 and 0.65 mm, respectively. The 2D measurements of T-ACL and IM-ACL were larger than the 3D measurements for both readers. The inter-reader reliability was excellent on 2D (0.81-0.96) and fair to excellent on 3D MRI (0.59-0.90). The mean arthroscopic IML-ACL was closer to that of 3D MRI compared to 2D MRI. The mean arthroscopic T-ACL was closer to 2D MRI than 3D MRI. CONCLUSIONS: Both 2D and 3D MRI show inter-reader reliability with small inter-modality mean differences in the measurements from the tibial or inter-meniscal ligament margins. KEY POINTS: • The mean differences between 2D and 3D measurements of tibia-ACL and intermeniscal ligament-ACL are small (< 1.2 mm). • As compared to arthroscopy, the mean T-ACL and IML-ACL were closer to measurements from 2D and 3D MRI, respectively. • Both 2D and 3D MRI can be reliably used to delineate ACL foot plate anatomy.

Scoliosis in Neurofibromatosis Type 1 on Whole-Body Magnetic Resonance Imaging: Frequency and Association With Intraspinal and Paraspinal Tumors.

OBJECTIVES: Scoliosis is a common orthopedic problem in patients with neurofibromatosis 1 (NF1). Spinal deformities are found in 77% of all NF1 cases, with no widely accepted etiology. This study aimed to evaluate the frequency and types of scoliosis in NF1 patients using whole-body magnetic resonance imaging and to assess the association of intraspinal and paraspinal tumors with the imaging findings of scoliosis. METHODS: A total of 122 NF1 patients with whole-body magnetic resonance imaging were found from the electronic medical records. Ninety-seven cases that met the inclusion criteria were identified. All patients underwent 3-T magnetic resonance imaging with automated software fusion of the 3 sets of short TI inversion recovery and 3-dimensional T1-weighted coronal images. Frequency and location of scoliosis and intraspinal and paraspinal tumors were recorded. Patients with severe dystrophic-type scoliosis were separately identified, and Cobb angles were measured for all such cases. Association analysis was performed. A P value less than 0.05 was considered statistically significant. RESULTS: Ninety-seven patients with NF1 were evaluated. Two had prior spinal surgery and were excluded. The final sample of 95 patients included 33 (35%) men and 62 (65%) women with a mean ± SD body mass index of 25.82 (4.96) kg/m2. Of the 95 patients, 43 (45.3%) had scoliosis, 13 of 43 (30.2%) of which were severely angled. Of the 95 patients, 25 (26.3%) had locoregional tumor presence. Intraclass correlation for Cobb angles measured 0.99 (confidence interval, 0.98-1.0). Fisher exact test determined no association between scoliosis and presence of either paraspinal or intraspinal tumors (P = 0.485). There was also no association between the tumors and severe dystrophic scoliosis (P = 1.0). CONCLUSIONS: This study found no association between the presence of locoregional spinal tumors and scoliosis in NF1 patients. This work adds to the body of knowledge of scoliosis in NF1 patients and infers that presence of scoliosis should not mandate immediate search for locoregional spinal tumors.