Imaging Characteristics of the Proximal Lateral Collateral Ligament of the Knee: Findings on Ultrasound and MRI With Histologic Correlation.

OBJECTIVES: Determine prevalence of increased signal intensity of the lateral collateral ligament (LCL) of the knee on MRI and decreased echogenicity on ultrasound, and compare with cadaveric histologic evaluation. METHODS: After IRB approval of this prospective study with informed consent, patients having knee MRI were additionally evaluated with ultrasound. Signal intensities of LCL on MRI (low, intermediate, high), echogenicity at ultrasound (hyperechoic, hypoechoic, anechoic), and extent of findings were assessed. Descriptive statistics, Wilcoxon signed ranked test, and intraclass correlation coefficient (ICC) were calculated. Two cadaveric knees were imaged with MRI and ultrasound, including histologic LCL evaluation. RESULTS: Seventy-three subjects were included (39 males, 34 females; mean age 48 ± 14 years) with 77 knee examinations. On MRI, low, intermediate, and high signals were present in 21% (16/77), 75% (58/77), and 4% (3/77), respectively. On ultrasound, echogenicity was assessed as hyperechoic, hypoechoic, and anechoic in 62% (48/77), 38% (29/77), and 0% (0/77), respectively. Mean length of increased signal was 8.6 mm (±4.9) on MRI, and 6.5 mm (±4.8) on ultrasound. The ICC showed a good to excellent intermodality reliability (0.735-0.899) without statistically significant difference for interreader measurements (P = .163-.795). Histology evaluation showed transition of ligament fibers to fibrocartilage at its insertion with increased connective tissue mucin corresponding to MRI and ultrasound findings. CONCLUSIONS: Increased signal intensity of the proximal LCL on ultrasound and MRI is common and corresponds to normal connective tissue mucin.

Medial Meniscal Extrusion Evaluation With Weight-Bearing Ultrasound: Correlation With MR Imaging Findings and Reported Symptoms: Correlation With MR Imaging Findings and Reported Symptoms.

OBJECTIVES: To compare medial meniscal extrusion on weight-bearing ultrasound (US) with supine US and magnetic resonance (MR) imaging correlating with meniscal pathology and reported symptoms. METHODS: IRB approved study with informed consent. Patients obtaining routine knee MR imaging for suspected knee pathology were prospectively evaluated with supine and weight-bearing US of the medial meniscus. Meniscal extrusion was measured independently by two fellowship-trained musculoskeletal radiologists. Correlation was made to presence or absence of meniscal degeneration or tear on MR imaging, as well as reported symptoms. Statistical significance was calculated via intraclass correlation coefficient (ICC) and analysis of variance (ANOVA). RESULTS: Ninety-nine knees from 95 subjects (50 males, 45 females; mean age 45 ± 15 years) were included. Mean medial meniscal extrusion measured at US for a normal meniscus (n = 36) was 0.8 mm when supine, increasing to 1.6 mm on weight-bearing. Mean meniscal extrusion in subjects with mucoid degeneration (n = 20) and those with meniscal tears (n = 43) was 1.6 mm, increasing to 2.3 mm with weight bearing. Inter-reader reliability showed ICC values of 0.853 to 0.940. There was a significant difference in medial meniscal extrusion comparing subjects with a normal medial meniscus at magnetic resonance imaging (MRI) and subjects with either meniscal degeneration or tear. There was no significant difference in degree of meniscal extrusion between subjects with meniscal degeneration or tear. There was trend of worsening symptoms and increasing functional limitations moving from normal meniscus to meniscal degeneration to meniscal tear. CONCLUSIONS: A normal meniscus shows lesser mobility between supine and upright position, than a pathologic meniscus. Both mucoid degeneration and meniscal tear demonstrate extrusion in the supine position, which increases with weight-bearing position.

MR imaging of the quadriceps femoris tendon: distal tear characterization and clinical significance of rupture types.

OBJECTIVE: To characterize quadriceps femoris tendon tears on magnetic resonance (MR) imaging regarding tear extent, location, and presence of bony avulsion. MATERIALS AND METHODS: IRB approval was obtained and informed consent was waived for this retrospective case series. Electronic medical records from all patients in our hospital system were searched for keywords: knee MR imaging, and quadriceps tendon rupture or tear. MRI studies were randomized and independently evaluated by two fellowship-trained musculoskeletal radiologists. MR imaging was used to characterize each individual quadriceps tendon as having tendinosis, tear (location, partial versus complete, size, and retraction distance), and bony avulsion. Knee radiographs were reviewed for presence or absence of bony avulsion. Descriptive statistics and inter-reader reliability (Cohen's Kappa and Wilcoxon-signed-rank test) were calculated. RESULTS: Fifty-two patients with 53 quadriceps tears were evaluated (45 males, 7 females; mean age: 51 ± 13 years). The vastus intermedius (VI) tendon more often incurred a partial rather than a complete tear (39.6% vs. 37.7%), while the rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL) incurred complete tears more commonly (64.2-66%). Subjects with bony avulsion on radiographs had higher-grade tears of the RF, VM, and VL tears (p = 0.020-0.043) but not the VI. Most tendons tore at or immediately proximal to the patella (84.8-93.6%). Gaps in retracted torn tendons measured between 2.3 and 2.7 cm. Inter-reader reliability was substantial to almost perfect (κ = 0.624-0.953). CONCLUSION: Quadriceps femoris tendon tears most commonly involve the RF or VL/VM layers usually in proximity to the patella. A bony avulsion correlates with a more extensive tear. KEY POINTS: • Quadriceps femoris tendon tears most commonly involve the rectus femoris or vastus lateralis/vastus medialis layers. • A rupture of the quadriceps femoris tendon usually occurs in proximity to the patella. • A bony avulsion of the patella correlates with a more extensive tear of the superficial and middle layers of the quadriceps tendon.

Ultra-high resolution 3D MRI for chondrocalcinosis detection in the knee-a prospective diagnostic accuracy study comparing 7-tesla and 3-tesla MRI with CT.

OBJECTIVES: To test the diagnostic accuracy of a 3D dual-echo steady-state (DESS) sequence at 7-T MRI regarding the detection of chondral calcific deposits of the knee in comparison to 3-T MRI, using CT as cross-sectional imaging reference standard. METHODS: CT and 7-T MRI (DESS) of knee joints in 42 patients with radiographically known chondrocalcinosis (13 of 42 bilateral) were prospectively acquired for all included patients (n = 55 knee joints). Additionally, 3-T MRI (DESS) was performed for 20 of these 55 knee joints. Two fellowship-trained musculoskeletal radiologists scored eight cartilage regions of each knee joint separately regarding presence of cartilage calcification, diagnostic confidence level, and sharpness of calcific deposits. In an explorative subanalysis, micro-CT of the menisci was evaluated after knee arthroplasty in one patient. Diagnostic performance metrics and nonparametric tests were used to compare between modalities. p values < 0.05 were considered to represent statistical significance. RESULTS: Sensitivity for chondrocalcinosis detection was significantly higher for 7-T MRI (100%) compared to 3-T MRI (reader 1: 95.9%, p = 0.03; reader 2: 93.2%, p = 0.002). The diagnostic confidence was significantly higher for both readers at 7 T compared to both 3-T MRI (p < 0.001) and to CT (p = 0.03). The delineation of chondral calcifications was significantly sharper for 7-T compared to both 3-T MRI and CT (p < 0.001, both readers). Micro-CT in one patient suggested that 7-T MRI may potentially outperform standard CT in diagnosing chondral calcifications. CONCLUSION: 3D-DESS imaging at 7-T MRI offers a significantly higher sensitivity in detection of chondral calcific deposits compared to 3-T MRI. KEY POINTS: • 3D dual-echo steady-state (DESS) MRI at 7 T has a higher sensitivity in detection of chondral calcific deposits compared to 3-T MRI (p ≤ 0.03). • 3D DESS MRI at 7 T yields no false-negative cases regarding presence of chondral calcific deposits. • 3D DESS MRI at 7 T offers better delineation and higher diagnostic confidence in detection of chondral calcific deposits compared to 3-T MRI (p < 0.001).

In vivo 3D tomography of the lumbar spine using a twin robotic X-ray system: quantitative and qualitative evaluation of the lumbar neural foramina in supine and upright position.

OBJECTIVES: Supine lumbar spine examinations underestimate body weight effects on neuroforaminal size. Therefore, our purpose was to evaluate size changes of the lumbar neuroforamina using supine and upright 3D tomography and to initially assess image quality compared with computed tomography (CT). METHODS: The lumbar spines were prospectively scanned in 48 patients in upright (3D tomographic twin robotic X-ray) and supine (30 with 3D tomography, 18 with CT) position. Cross-sectional area (CSA), cranio-caudal (CC), and ventro-dorsal (VD) diameters of foramina were measured by two readers and additionally graded in relation to the intervertebral disc height. Visibility of bone/soft tissue structures and image quality were assessed independently on a 5-point Likert scale for the 18 patients scanned with both modalities. Descriptive statistics, Wilcoxon's signed-rank test (p < 0.05), and interreader reliability were calculated. RESULTS: Neuroforaminal size significantly decreased at all levels for both readers from the supine (normal intervertebral disc height; CSA 1.25 ± 0.32 cm2; CC 1.84 ± 0.24 cm2; VD 0.88 ± 0.16 cm2) to upright position (CSA 1.12 ± 0.34 cm2; CC 1.78 ± 0.24 cm2; VD 0.83 ± 0.16 cm2; each p < 0.001). Decrease in intervertebral disc height correlated with decrease in foraminal size (supine: CSA 0.88 ± 0.34 cm2; CC 1.39 ± 0.33 cm2; VD 0.87 ± 0.26 cm2; upright: CSA 0.83 ± 0.37 cm2, p = 0.010; CC 1.32 ± 0.33 cm2, p = 0.015; VD 0.80 ± 0.21 cm2, p = 0.021). Interreader reliability for area was fair to excellent (0.51-0.89) with a wide range for cranio-caudal (0.32-0.74) and ventro-dorsal (0.03-0.70) distances. Image quality was superior for CT compared with that for 3D tomography (p < 0.001; κ, CT = 0.66-0.92/3D tomography = 0.51-1.00). CONCLUSIONS: The size of the lumbar foramina is smaller in the upright weight-bearing position compared with that in the supine position. Image quality, especially nerve root delineation, is inferior using 3D tomography compared to CT. KEY POINTS: • Weight-bearing examination demonstrates a decrease of the neuroforaminal size. • Patients with higher decrease in intervertebral disc showed a narrower foraminal size. • Image quality is superior with CT compared to 3D tomographic twin robotic X-ray at the lumbar spine.

Comparison of 3D X-ray tomography with computed tomography in patients with distal extremity fractures.

OBJECTIVE: To compare fracture detection, image quality, and radiation dose in patients with distal extremity fractures using 3D tomography and computed tomography (CT). MATERIALS AND METHODS: IRB approval was obtained including informed consent for this prospective study from June to December 2016. Patients diagnosed with an acute fracture at CT were consecutively scanned on the same day using 3D tomography. Anatomical location (effected bone and location within the bone) and morphological characteristics of fractures (avulsion, articular involvement, mono- vs. multifragmented, displacement), visibility of bone/soft tissue structures, and image quality were assessed independently by two blinded readers on a 5-point Likert scale. Dose-length-product (DLP; mGy*cm) was compared between both modalities. Descriptive statistics, Wilcoxon signed rank test (P < 0.05), Student's t test (P < 0.05), and Cohen's kappa (κ) for interreader reliability were calculated. RESULTS: In 46 patients (28 males; 18 females; mean age, 53 ± 20 years) with 28 hand/wrist and 18 foot/ankle examinations, 86 out of 92 fractures were diagnosed with 3D tomography compared with CT. No false-positive finding occurred at 3D tomography. The six missed fractures on 3D tomography were five avulsion fractures of the carpals/metacarpals or tarsals/metatarsals, respectively, and one nondisplaced fracture of the capitate. Interreader agreement of anatomical location and morphological characteristics was substantial to almost perfect for upper (κ = 0.80-0.96) and lower (κ = 0.70-0.97) extremity fractures. Visibility of bone and soft tissue structures and image quality were slightly inferior using 3D tomography compared with CT (upper extremity P < 0.001-0.038 and lower extremity P < 0.001-0.035). DLP of a comparable scan coverage was significantly lower for 3D tomography (P < 0.001) for both upper (3D mean, 19.4 ± 5.9 mGy*cm; estimated CT mean, 336.5 ± 52.2 mGy*cm) and lower extremities (3D mean, 24.1 ± 11.1 mGy*cm; estimated CT mean, 182.9 ± 6.5 mGy*cm). Even the highest DLP with 3D tomography was < 30% of the mean estimated CT dose of a comparable area of coverage. CONCLUSION: Fracture assessment of peripheral extremities is reliable utilizing a low-dose 3D tomography X-ray system, with slightly reduced image quality.

Sonography of Wrist Ganglion Cysts: Which Location Is Most Common?

OBJECTIVES: The literature states that wrist ganglion cysts are most commonly dorsal; however, our experience suggests a volar location is more common. The purpose of this study was to identify the locations of ganglion cysts of the wrist as imaged with sonography. METHODS: After Institutional Review Board approval with informed consent waived, retrospective review of wrist sonography reports from January to April 2016 was completed. Only patients who had a comprehensive evaluation that included the dorsal and volar wrist were included. Ultrasound images were reviewed to characterize wrist ganglion cysts. RESULTS: The study group consisted of 98 subjects (78% female, 22% male) (median age, 51 years; range 13-79) with 124 wrist ganglion cysts, where 69% (86 of 124) were volar and 31% (38 of 124) were dorsal. Ganglion cysts were located between the radial artery and flexor carpi radialis in 63% (78 of 124), followed by a dorsal location superficial to the scapholunate ligament in 20% (25 of 124), other dorsal locations in 11% (13 of 124), and other volar locations in 6% (8 of 124). With dorsal ganglion cysts, the scapholunate ligament when imaged appeared normal in 91% (20 of 22). Ganglion cysts were multilocular/multilobular in all subjects. CONCLUSIONS: The most common location for wrist ganglion cysts is in the volar wrist, particularly between the radial artery and flexor carpi radialis tendon, appearing multilocular or multilobular with a mean largest dimension of 1.0 cm. Given the propensity of ganglion cysts to occur at this site, attention to this area when imaging the wrist with sonography or magnetic resonance imaging should be considered.

Meniscal pathologies on MRI correlate with increased bone tracer uptake in SPECT/CT.

OBJECTIVES: To assess the relationship of subchondral bone tracer uptake (BTU) on SPECT/CT and meniscal pathologies on MRI in patients with painful knees. METHODS: Twenty-five patients who had MRI and SPECT/CT within 3 months without knee surgery or grade ≥3 cartilage lesions were prospectively included. Maximum values of each subchondral femorotibial area were quantified and a ratio was calculated in relation to a femoral shaft reference region, which represented the BTU background activity. Meniscal lesions were graded (intact/degeneration/tear) and meniscal extrusion (no/yes) was assessed using MRI by two musculoskeletal radiologists blinded to the SPECT/CT findings. One-tailed Spearman correlations served for statistics (p < 0.05). RESULTS: Knees with meniscal degeneration or tear showed a significantly higher BTU in the medial femorotibial compartment (p = 0.045) when compared to intact menisci. Meniscal degeneration was associated with an increased BTU in the lateral femorotibial compartment; however, this was not statistically significant (p = 0.143). Patients with an extruded meniscus showed significantly higher BTU compared to a non-extruded meniscus (p < 0.020). CONCLUSIONS: Medial femorotibial BTU in SPECT/CT was associated with meniscal pathologies. Highest BTU was found in patients with meniscal tears. SPECT/CT appears to be a useful imaging modality to identify patients with overloading or early osteoarthritis. KEY POINTS: • Meniscal degeneration and tears correlate significantly with increased BTU using SPECT/CT. • Medial meniscus extrusion is associated with an increased BTU in SPECT/CT. • SPECT/CT allows detection of overloading and early osteoarthritis.

Comparison of image quality and radiation dose between split-filter dual-energy images and single-energy images in single-source abdominal CT.

OBJECTIVES: To compare image quality and radiation dose of abdominal split-filter dual-energy CT (SF-DECT) combined with monoenergetic imaging to single-energy CT (SECT) with automatic tube voltage selection (ATVS). METHODS: Two-hundred single-source abdominal CT scans were performed as SECT with ATVS (n = 100) and SF-DECT (n = 100). SF-DECT scans were reconstructed and subdivided into composed images (SF-CI) and monoenergetic images at 55 keV (SF-MI). Objective and subjective image quality were compared among single-energy images (SEI), SF-CI and SF-MI. CNR and FOM were separately calculated for the liver (e.g. CNRliv) and the portal vein (CNRpv). Radiation dose was compared using size-specific dose estimate (SSDE). Results of the three groups were compared using non-parametric tests. RESULTS: Image noise of SF-CI was 18% lower compared to SEI and 48% lower compared to SF-MI (p < 0.001). Composed images yielded higher CNRliv over single-energy images (23.4 vs. 20.9; p < 0.001), whereas CNRpv was significantly lower (3.5 vs. 5.2; p < 0.001). Monoenergetic images overcame this inferiority in CNRpv and achieved similar results compared to single-energy images (5.1 vs. 5.2; p > 0.628). Subjective sharpness was equal between single-energy and monoenergetic images and diagnostic confidence was equal between single-energy and composed images. FOMliv was highest for SF-CI. FOMpv was equal for SEI and SF-MI (p = 0.78). SSDE was significant lower for SF-DECT compared to SECT (p < 0.022). CONCLUSIONS: The combined use of split-filter dual-energy CT images provides comparable objective and subjective image quality at lower radiation dose compared to single-energy CT with ATVS. KEY POINTS: • Split-filter dual-energy results in 18% lower noise compared to single-energy with ATVS. • Split-filter dual-energy results in 11% lower SSDE compared to single-energy with ATVS. • Spectral shaping of split-filter dual-energy leads to an increased dose-efficiency.

Increased bone tracer uptake in symptomatic patients with ACL graft insufficiency: a correlation of MRI and SPECT/CT findings.

PURPOSE: Magnetic resonance imaging (MRI) and single-photon emission computerised tomography/computerised tomography (SPECT/CT) are used as diagnostic tools in symptomatic patients after reconstruction of the anterior cruciate ligament (ACL). The benefit of SPECT/CT in comparison with MRI is under debate. The purpose of this study was to investigate whether and how bone tracer uptake (BTU) intensity and distribution in SPECT/CT correlate with MRI findings in symptomatic patients after ACL reconstruction. METHODS: Twenty-nine patients (male:female = 22:7, mean age ± SD 26 ± 10 years) with symptoms of pain and instability after ACL reconstruction were retrospectively investigated using prospectively acquired SPECT/CT and MRI. On MRI graft tear, graft signal intensity, bone marrow oedema, tunnel cyst formation, roof impingement, roof osteophytes, local arthrofibrosis, joint effusion and synovial thickness were analysed by two readers blinded to the BTU results. BTU was anatomically localised and volumetrically quantified. Spearman's rho test was used for correlation of BTU in SPECT/CT and MRI findings (p < 0.05). RESULTS: SPECT/CT showed increased femoral and tibial BTU in patients with MRI-confirmed graft tear, signal hyperintensity of the intraarticular graft section, joint effusion, synovial thickening, roof osteophytes and bone marrow oedema. Cyst formation in the femoral tunnel results in significantly reduced BTU in femur and tibia. No correlation of increased BTU was found for graft impingement and graft arthrofibrosis. CONCLUSIONS: Bone tracer uptake in SPECT/CT and defined MRI findings in symptomatic patients after ACL reconstruction were correlated. Both imaging modalities have a definite role in post-operative diagnostic and have established their value in those patients. This study provides a better understanding of the clinical value of SPECT/CT versus MRI in the clinical decision-making process. SPECT/CT provides a window into the in vivo loading of the joint as well as bone remodelling and graft incorporation process. In addition, ACL graft insufficiency can be detected by increased BTU. LEVEL OF EVIDENCE: Retrospective cohort study, Level III.

Organ-based tube current modulation in a clinical context: Dose reduction may be largely overestimated in breast tissue.

OBJECTIVES: Organ-based tube current modulation aims to reduce exposure to radiosensitive organs like the breasts by considering their anatomical location and altering tube current during rotation. Former phantom studies demonstrated a dose reduction of 20-37 %. Our study aimed to estimate the potential of dose reduction with this technique in relation to the actual location of breast tissue in a large clinical cohort. METHODS: A 1-year cohort of chest CTs of females (N=1,263) was retrospectively evaluated. To estimate the relative dose effect, breast location was analysed by measuring the angle range of glandular tissue within the different dose zones. Relative exposure compared with constant tube current was calculated. Descriptive statistics and Wilcoxon-test were applied. RESULTS: Only 63 % of angle range of glandular breast tissue was found inside the reduced dose zone. The estimated mean relative dose reduction was lower than observed in former phantom studies(16 % vs. 20-37 %) but still significant compared to constant tube current (p<0.0001). CONCLUSIONS: Although organ-based tube current modulation results in a significant reduction of breast exposure compared to non-modulated irradiation, the technique cannot unfold its full potential, because breast tissue is often located outside the reduced dose zone, resulting in significantly lower dose reduction than expected. KEY POINTS: • OBTCM results in significant dose reduction compared to constant tube current scans. • A substantial portion of glandular tissue lies outside the reduced dose zone. • Potential dose reduction using organ-based tube current modulation may be overestimated.

Musculoskeletal imaging in preventive medicine.

The aim is to review the modalities in musculoskeletal imaging with view on the prognostic impact for the patient's and for social outcome and with view on three major fields of preventive medicine: nutrition and metabolism, sports, and patient education. The added value provided by preventive imaging is (1) to monitor bone health and body composition with a broad spectrum of biomarkers, (2) to detect and quantify variants or abnormalities of nerves, muscles, tendons, bones, and joints with a risk of overuse, rupture, or fracture, and (3) to develop radiology reports from the widely used narrative format to structured text and multimedia datasets. The awareness problem is a term for describing the underreporting and the underdiagnosis of fragility fractures in osteoporosis.

4D-SPECT/CT in orthopaedics: a new method of combined quantitative volumetric 3D analysis of SPECT/CT tracer uptake and component position measurements in patients after total knee arthroplasty.

OBJECTIVE: The purpose was to evaluate the intra- and inter-observer reliability of combined quantitative 3D-volumetric single-photon emission computed tomography (SPECT)/CT analysis including size, intensity and localisation of tracer uptake regions and total knee arthroplasty (TKA) position. MATERIALS AND METHODS: Tc-99m-HDP-SPECT/CT of 100 knees after TKA were prospectively analysed. The anatomical areas represented by a previously validated localisation scheme were 3D-volumetrically analysed. The maximum intensity was recorded for each anatomical area. Ratios between the respective value and the mid-shaft of the femur as the reference were calculated. Femoral and tibial TKA position (varus-valgus, flexion-extension, internal rotation- external rotation) were determined on 3D-CT. Two consultant radiologists/nuclear medicine physicians interpreted the SPECT/CTs twice with a 2-week interval. The inter- and intra-observer reliability was determined (ICCs). Kappa values were calculated for the area with the highest tracer uptake between the observers. RESULTS: The measurements of tracer uptake intensity showed excellent inter- and intra-observer reliabilities for all regions (tibia, femur and patella). Only the tibial shaft area showed ICCs <0.89. The kappa values were almost perfect (0.856, p < 0.001; 95 % CI 0.778, 0.922). For measurements of the TKA position, there was strong agreement within and between the readings of the two observers; the ICCs for the orientation of TKA components for inter- and intra-observer reliability were nearly perfect (ICCs >0.84). CONCLUSION: This combined 3D-volumetric standardised method of analysing the location, size and the intensity of SPECT/CT tracer uptake regions ("hotspots") and the determination of the TKA position was highly reliable and represents a novel promising approach to biomechanics.

The biomechanical consequence of posterior interventions at the thoracolumbar spine on the passively stabilized flexed posture.

In the flexed end-of-range position (e.g., during slumped sitting), the trunk is passively stabilized. Little is known about the biomechanical consequence of posterior approaches on passive stabilization. The aim of this study is to investigate the effect of posterior surgical interventions on local and distant spinal regions. While being fixed at the pelvis, five human torsos were passively flexed. The change in spinal angulation at Th4, Th12, L4 and S1 was measured after level-wise longitudinal incisions of the thoracolumbar fascia, the paraspinal muscles, horizontal incisions of the inter- & supraspinous ligaments (ISL/SSL) and horizontal incision of the thoracolumbar fascia and the paraspinal muscles. Lumbar angulation (Th12-S1) was increased by 0.3° for fascia, 0.5° for muscle and 0.8° for ISL/SSL-incisions per lumbar level. The effect of level-wise incisions at the lumbar spine was 1.4, 3.5 and 2.6 times greater compared to thoracic interventions for fascia, muscle and ISL/SSL respectively. The combined midline interventions at the lumbar spine were associated with 2.2° extension of the thoracic spine. Horizontal incision of the fascia increased spinal angulation by 0.3°, while horizontal muscle incision resulted in a collapse of 4/5 specimens. The thoracolumbar fascia, the paraspinal muscle and the ISL/SSL are important passive stabilizers for the trunk in the flexed end-of-range position. Lumbar interventions needed for approaches to the spine have a larger effect on spinal posture than thoracic interventions and the increase of spinal angulation at the level of the intervention is partially compensated at the neighboring spinal regions.

Biomechanical considerations of the posterior surgical approach to the lumbar spine.

BACKGROUND CONTEXT: The effect of the posterior midline approach to the lumbar spine, relevance of inter- and supraspinous ligament (ISL&SSL) sparing, and potential of different wound closure techniques are largely unknown despite their common use. PURPOSE: The aim of this study was to quantify the effect of the posterior approach, ISL&SSL resection, and different suture techniques. STUDY DESIGN: Biomechanical cadaveric study. METHODS: Five fresh frozen human torsi were stabilized at the pelvis in the erect position. The torsi were passively loaded into the forward bending position and the sagittal angulation of the sacrum, L4 and T12 were measured after a level-wise posterior surgical approach from L5/S1 to T12/L1 and after a level-wise ISL&SSL dissection of the same sequence. The measurements were repeated after the surgical closure of the thoracolumbar fascia with and without suturing the fascia to the spinous processes. RESULTS: Passive spinal flexion was increased by 0.8±0.3° with every spinal level accessed by the posterior approach. With each additional ISL&SSL resection, a total increase of 1.6±0.4° was recorded. Suturing of the thoracolumbar fascia reduced this loss of resistance against lumbar flexion by 70%. If the ISL&SSL were resected, fascial closure reduced the lumbar flexion by 40% only. In both settings, suturing the fascia to the spinous processes did not result in a significantly different result (p=.523 and p=.730 respectively). CONCLUSION: Each level accessed by a posterior midline approach is directly related to a loss of resistance against passive spinal flexion. Additional resection of ISL&SSL multiplies it by a factor of two. CLINICAL SIGNIFICANCE: The surgical closure of the thoracolumbar fascia can reduce the above mentioned loss of resistance partially. Suturing the fascia to the spinal processes does not result in improved passive stability.

Basic and Advanced Metal-Artifact Reduction Techniques at Ultra-High Field 7-T Magnetic Resonance Imaging-Phantom Study Investigating Feasibility and Efficacy.

OBJECTIVES: The aim of this study was to demonstrate the feasibility and efficacy of basic (increased receive bandwidth) and advanced (view-angle tilting [VAT] and slice-encoding for metal artifact correction [SEMAC]) techniques for metal-artifact reduction in ultra-high field 7-T magnetic resonance imaging (MRI). MATERIALS AND METHODS: In this experimental study, we performed 7-T MRI of titanium alloy phantom models composed of a spinal pedicle screw (phantom 1) and an intervertebral cage (phantom 2) centered in a rectangular LEGO frame, embedded in deionized-water-gadolinium (0.1 mmol/L) solution. The following turbo spin-echo sequences were acquired: (1) nonoptimized standard sequence; (2) optimized, that is, increased receive bandwidth sequence (oBW); (3) VAT; (4) combination of oBW and VAT (oBW-VAT); and (5) SEMAC. Two fellowship-trained musculoskeletal radiologists independently evaluated images regarding peri-implant signal void and geometric distortion (a, angle measurement and b, presence of circular shape loss). Statistics included Friedman test and Cochran Q test with Bonferroni correction for multiple comparisons. P values <0.05 were considered to represent statistical significance. RESULTS: All metal-artifact reduction techniques reduced peri-implant signal voids and diminished geometric distortions, with oBW-VAT and SEMAC being most efficient. Compared with nonoptimized sequences, oBW-VAT and SEMAC produced significantly smaller peri-implant signal voids (all P ≤ 0.008) and significantly smaller distortion angles (P ≤ 0.001). Only SEMAC could significantly reduce distortions of circular shapes in the peri-implant frame (P ≤ 0.006). Notably, increasing the number of slice-encoding steps in SEMAC sequences did not lead to a significantly better metal-artifact reduction (all P ≥ 0.257). CONCLUSIONS: The use of basic and advanced methods for metal-artifact reduction at 7-T MRI is feasible and effective. Both a combination of increased receive bandwidth and VAT as well as SEMAC significantly reduce the peri-implant signal void and geometric distortion around metal implants.

Hand-Held Portable Versus Conventional Cart-Based Ultrasound in Musculoskeletal Imaging.

BACKGROUND: Portable ultrasound machines are now common, used for point-of-care applications and needle guidance for percutaneous procedures; however, the effectiveness of portable ultrasound in evaluation of the musculoskeletal system has not been fully assessed. PURPOSE: To prospectively evaluate the use of portable hand-held ultrasound in comparison with conventional cart-based ultrasound in evaluation of the musculoskeletal system. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: In this institutional review board-approved, prospective study, 100 consecutive patients with informed consent were imaged through use of both portable and cart-based ultrasound equipment using 12-5 MHz linear transducers. Agreement in ultrasound diagnosis was documented along with expected clinical changes in management if there was disagreement (definitely no, probably no, uncertain, probably yes, definitely yes). Imaging details of disagreement cases were recorded, and descriptive statistics were calculated. RESULTS: There were 42 male and 58 female patients (mean ± SD age, 53 ± 13 years) imaged over a time period of 20 months. Anatomic areas scanned were the shoulder (n = 30), elbow (n = 11), hand and wrist (n = 15), hip (n = 10), knee (n = 11), foot and ankle (n = 12), and others (n = 11). Scanning with conventional ultrasound revealed abnormality in 92% of patients. Agreement in diagnosis made between portable versus cart-based ultrasound was found in 65% of patients. In the 35% of patients with discordant results, the change in diagnosis resulted in no change in clinical management in 46%, probably no change in 29%, uncertain change in 14%, probable change in 11%, and definite change in 0%. The diagnoses changing management (4%; 4/100) included nondetection of a satellite nodule (n = 1), ganglion cyst (n = 1), hernia (n = 1), and underestimated tendon tear (n = 1). CONCLUSION: When compared with conventional cart-based ultrasound, a musculoskeletal diagnosis using portable hand-held ultrasound was concordant or was discordant without clinical relevance in 96% (96/100) of patients. Knowledge of benefits and limitations of portable hand-held ultrasound will help determine areas where specific types of ultrasound equipment can be used.

Mid-term results after in situ pinning and hip arthroscopy for mild slipped capital femoral epiphysis: a minimum five-year follow-up.

PURPOSE: In situ pinning of mild slipped capital femoral epiphysis (SCFE) results in an aspherical head-neck junction and arthroscopic osteochondroplasty can successfully correct the head-neck junction. However, whether the correction stays stable over at least five years remains unknown. METHODS: In a retrospective and consecutive series, 11 patients with a mean age of 12 years (range, 10 years to 15 years) were included. All patients were treated for mild SCFE with in situ pinning and staged hip arthroscopy correcting the head-neck junction. All patients were assessed clinically and radiographically (radiograph and magnetic resonance imaging (MRI)) pre-operatively, 12 weeks and at least five years' post-operatively. RESULTS: The mean range of motion (ROM) for flexion and internal rotation was stable over time with 100° (sd 4) and 21° (sd 6), respectively at the last follow-up. The mean alpha angle decreased from pre-operative 64° (range 61° to 68°) to 12 weeks post-operative 49° (range 46° to 52°; p = 0.001) and stayed stable over time. New superficial cartilage damage on either the acetabular or femoral side was seen in each three patients. Progressive labral degeneration was present in two patients. CONCLUSION: In situ pinning and staged hip arthroscopy for the correction of mild SCFE is safe, restores normal alpha angles and reveals stable morphological correction at mid-term follow-up. Furthermore, the clinical results were excellent with almost normalized internal hip rotation at mid-term follow-up in patients who had reached adulthood. However, there was some joint deterioration, but without negative impact on subjective and clinical outcome after at least five years. LEVEL OF EVIDENCE: IV.

Cartilage icing and chondrocalcinosis on knee radiographs in the differentiation between gout and calcium pyrophosphate deposition.

OBJECTIVE: To determine if findings of "cartilage icing" and chondrocalcinosis on knee radiography can differentiate between gout and calcium pyrophosphate deposition (CPPD). METHODS: IRB-approval was obtained and informed consent was waived for this retrospective study. Electronic medical records from over 2.3 million patients were searched for keywords to identify subjects with knee aspiration-proven cases of gout or CPPD. Radiographs were reviewed by two fellowship-trained musculoskeletal radiologists in randomized order, blinded to the patients' diagnoses. Images were evaluated regarding the presence or absence of cartilage icing, chondrocalcinosis, tophi, gastrocnemius tendon calcification, and joint effusion. Descriptive statistics, sensitivity, specificity, positive and negative predictive values, and accuracy were calculated. RESULTS: From 49 knee radiographic studies in 46 subjects (31 males and 15 females; mean age 66±13 years), 39% (19/49) showed gout and 61% (30/49) CPPD on aspiration. On knee radiographs, cartilage icing showed a higher sensitivity for CPPD than gout (53-67% and 26%, respectively). Chondrocalcinosis also showed a higher sensitivity for CPPD than gout (50-57% versus 5%), with 95% specificity and 94% positive predictive value for diagnosis of CPPD versus gout. Soft tissue tophus-like opacities were present in gout at the patellar tendon (5%, 1/19) and at the popliteus groove in CPPD (15%, 4/27). Gastrocnemius tendon calcification was present in 30% (8/27) of subjects with CPPD, and 5% (1/19) of gout. CONCLUSION: In subjects with joint aspiration-proven crystal disease of the knee, the radiographic finding of cartilage icing was seen in both gout and CPPD. Chondrocalcinosis (overall and hyaline cartilage) as well as gastrocnemius tendon calcification positively correlated with the diagnosis of CPPD over gout.