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Clinically measured Quadriceps angle (Q-angle) has low reliability. Measurement of angle between femoral shaft and patellar tendon (FSPT angle) on routine knee MRI was described in this study to represent the lateral vector forces of quadriceps mechanism. The cross-sectional study was designed to compare this angle between subjects with objective patellofemoral instability (PFI) versus those without PFI, to assess its reliability, and to assess its validity in terms of its ability to differentiate between PFI and non-PFI subjects using the “Receiver Operating Characteristic” (ROC) curve. MRI scans of 20 subjects with PFI and 20 without PFI were obtained. FSPT angle was measured in each MRI by three different raters. In addition, the clinical Q-angle was also measured in the control group. The FSPT angle was significantly higher in PFI group as compared with the non-PFI group (p

To compare diagnostic performance of a 5-min knee MRI protocol to that of a standard knee MRI. One hundred 3 T (100 patients, mean 38.8 years) and 50 1.5 T (46 patients, mean 46.4 years) MRIs, consisting of 5 fast, 2D multi-planar fast-spin-echo (FSE) sequences and five standard multiplanar FSE sequences, from two academic centers (1/2015–1/2016), were retrospectively reviewed by four musculoskeletal radiologists. Agreement between fast and standard (interprotocol agreement) and between standard (intraprotocol agreement) readings for meniscal, ligamentous, chondral, and bone pathology was compared for interchangeability. Frequency of major findings, sensitivity, and specificity was also tested for each protocol. Interprotocol agreement using fast MRI was similar to intraprotocol agreement with standard MRI (83.0–99.5%), with no excess disagreement (≤ 1.2; 95% CI, −4.2 to 3.8%), across all structures. Frequency of major findings (1.1–22.4% across structures) on fast and standard MRI was not significantly different (p ≥ 0.215), except more ACL tears on fast MRI (p = 0.021) and more cartilage defects on standard MRI (p

To compare knee MRI performed with the integrated parallel acquisition technique (PAT) and simultaneous multislice (SMS) turbo spin echo (TSE) T2-weighted (T2w) sequences with conventional TSE sequences in pediatric patients. This was a retrospective IRB-approved study. Seventy-four subjects (26 male, 48 female, mean age 15.3 years, range 8–20) underwent 3-T MRI of the knee with a T2w TSE pulse sequence prototype with four-fold PAT and SMS acceleration as well as the standard PAT-only accelerated sequences. Images were anonymized and two study folders were created: one examination with only T2w PAT2 images (conventional examination) and one examination with only T2w SMS2/PAT2 sequences (SMS examination). Two readers rated examinations for 15 specific imaging findings and 5 quality metrics. Interreader agreement was measured. Signal to noise (SNR) and contrast to noise (CNR) were measured for SMS and conventional T2w sequences. Consensus review demonstrated diagnostic quality performance of SMS examinations with respect to all 15 structures. Average area under the curve (AROC) was 0.95 and 0.97 for readers 1 and 2, respectively. The conventional sequence was favored over SMS for four out of five quality metrics (p

To define the number and distribution of osteophytes (OPs) in bilateral knee MRI (magnetic resonance imaging) of patients with unilateral anterior cruciate ligament (ACL) rupture.Bilateral knee MRIs of 20 patients with unilateral ACL rupture and reconstruction were retrospectively analyzed for OPs. OPs were graded following the KOSS (knee OA scoring system) classification and their compartmental distribution was assessed following the WORMS (Whole-Organ Magnetic Resonance Imaging Score) classification.All examined knees revealed OPs. Knees with ACL rupture showed significant (p 0.001) higher total numbers of OPs (mean 11.6; SD ± 4.4) than knees with intact ACL (mean 5.1; SD ± 2.3). Knees with ACL rupture showed increased OP formation in all knee compartments with predominance of marginal OPs in the lateral femorotibial compartment especially on the tibia.Our results show that after knee injury with ACL rupture and reconstruction, all knee compartments were involved in post-traumatic increase of OP formation. The most affected compartment was the lateral femorotibial compartment on the tibial side.

Knee pain in young patients is a common indication for knee MRI. Many static and dynamic internal derangements of the patellofemoral joint in these patients lead to various secondary MRI findings. This article focuses on how to systematically approach, detect, and emphasize the importance of these findings in the diagnosis of patellofemoral tracking and impingement syndromes with relevant case examples.

Purpose The purpose of the study was to relate magnetic resonance imaging (MRI) features at baseline with radiographically determined joint space narrowing (JSN) in the medial compartment of the knee after 2 years in a group of patients with symptomatic osteoarthritis at multiple joint sites. Materials and methods MRI of the knee and standardized radiographs were obtained at baseline and after 2 years in 186 patients (81% female; aged 43–76 years; mean 60 years). MRI was analyzed for bone marrow lesions, cysts, osteophytes, hyaline cartilage defects, joint effusion, and meniscal pathology in the medial compartment. Radiographs were scored semiquantitatively for JSN in the medial tibiofemoral joint using the Osteoarthritis Research Society International (OARSI) atlas. Radiological progression was defined as ≥1 grade increase. Associations between baseline magnetic resonance (MR) parameters and subsequent radiographic JSN changes were assessed using logistic regression. Relative risk (RR) was then calculated. Results Radiographic progression of JSN was observed in 17 (9.1%) of 186 patients. Eleven patients had a Kellgren and Lawrence (KL) score of ≥2. A significant association was observed between all patients and meniscal tears (RR 3.57; confidence interval (CI) 1.08–10.0) and meniscal subluxation (RR 2.73; CI 1.20–5.41), between KL

To describe MRI features of an entity consisting of medial knee pain and edema between the posteromedial femoral condyle (PMFC), sartorius and/or gracilis tendons and determine whether reduced tendon-bone distances may account for these findings. We retrospectively identified MRI cases of edema between the PMFC, sartorius and/or gracilis tendons (25 subjects, 26 knees). Two musculoskeletal radiologists independently graded edema and measured the sartorius- and gracilis-PMFC distances and knee flexion angle. Age- and gender-matched subjects with normal knee MRIs (27 subjects, 27 knees) served as controls for measurements. Statistical analyses compared abnormal to control subjects. Sartorius-PMFC and gracilis-PMFC spaces were narrower in abnormal compared to control subjects (1.6 ± 1.0 vs. 2.1 ± 1.2 mm, P = 0.04; 2.3 ± 2.0 vs. 4.6 ± 3.0 mm, P = 0.002, respectively). The knee flexion angle was similar between groups (P > 0.05). In subjects with clinical information, medial knee pain was the main complaint in 58 % (15/26) of abnormal subjects, with 42 % (11/26) having clinical suspicion of medial meniscal tear. Edema between the PMFC, sartorius and/or gracilis was mild in 54 % (14/26), moderate in 35 % (9/26) and severe in 12 % (3/26), and it was most frequent deep to both the sartorius and gracilis (50 %, 13/26). Edema between the PMFC, sartorius and/or gracilis tendons identified on knee MRI may be associated with medial knee pain and may represent a friction syndrome.

Bioabsorbable interference screws are commonly used to secure the graft during anterior cruciate ligament (ACL) reconstruction, in part because they result in less image degradation on subsequent magnetic resonance imaging (MRI). However, some bioabsorbable screws are associated with abnormalities on MRI examination not reported with metallic interference screws. We describe a finding on knee MRI examination after ACL reconstruction using a polylactide carbonate (PLC) bioabsorbable screw that we believe to be previously unreported with any other bioabsorbable screws. The finding raised suspicion of hemorrhage or infection, neither of which were present clinically. Analysis of tissue from the tibial tunnel suggested an explanation for the MRI finding: calcite crystals. An additional five patients with knee MRI examinations after ACL reconstruction using a PLC screw were reviewed and correlated with clinical findings with four having similar imaging abnormalities present. The PLC (Calaxo screw, Smith and Nephew, Andover, MA) screw used in these patients has been recalled in the United States and Europe by the manufacturer after a greater than expected incidence of adverse reactions, and legal action may be pending.

OBJECTIVE: To identify the commonly occurring patterns of small displaced tears of the menisci of the knee on magnetic resonance imaging (MRI). MATERIALS AND METHODS: A retrospective review of knee MRI scans over 16 months at two hospitals provided 70 studies with 73 displaced meniscal fragments for analysis. Fragment position was recorded. RESULTS: Two common positions were identified for medial fragments. For the medial meniscus, 93% of fragments were positioned medially or posterolaterally. The medially displaced fragments were positioned in either the superior or inferior recesses. Lateral meniscal fragments were more evenly dispersed. CONCLUSION: The pattern of small displaced tears of the medial meniscus is highly predictable. Awareness of the typical locations of these fragments should aid the reporter in identifying these lesions on MRI.

To test the hypothesis that in symptomatic patients, knees in which MRI examinations demonstrate no significant effusion will also be free of internal derangement. One hundred and fifteen knee MRI examinations performed between March 2002 and June 2002 at our institution were retrospectively reviewed, evaluating for both the presence of knee effusions and concurrent internal derangement. The amount of joint fluid was measured quantitatively by obtaining anteroposterior measurements in the midline and lateral aspects of the suprapatellar pouch using sagittal MR images. These measurements were then correlated with presence or absence of MRI-demonstrated internal derangement and statistical analysis was performed. Of the 115 knee MRI examinations evaluated, 47 (41%) were negative for internal derangement and 68 (59%) were positive for internal derangement. Thirty-six of 115 (31%) examinations showed joint fluid with anteroposterior measurement of 10 mm or less in the lateral aspect of the suprapatellar pouch. Of these, 31 (86%) showed no concurrent internal derangement. Statistical analysis was also performed using other lateral suprapatellar pouch cutoff values. While knees in which MRI examinations demonstrate no significant effusion are most often free of internal derangement, there remain a significant number which will exhibit internal derangement. An anteroposterior measurement of 10 mm or less in the lateral aspect of the suprapatellar pouch is a reasonable threshold value for distinguishing a physiologic from a pathologic amount of joint fluid.

Although the popliteomeniscal fascicles are important stabilizers of the lateral meniscus, there have been few studies of their MR appearance. We wished to determine: (1) whether the fascicles are normally seen on MR imaging, and (2) whether certain imaging factors influenced their visualization.We reviewed the sagittal MR images of 66 consecutive patients who had no evidence of injury to the lateral compartment. We determined the frequencies of MR visualization of the superior and inferior popliteomeniscal fascicles, and whether visualization was affected by the weighting of spin echo sequences, the presence of a joint effusion, slice placement relative to the fascicles, and windowing of the images.Both popliteomeniscal fascicles were seen in 64 of the 66 patients. The fascicles were better seen on T2-weighted images than on proton-density weighted images (P0.01). On the T2-weighted images, fascicle visualization was not significantly affected by the presence or absence of an effusion, slice placement or image windowing (P=0.2 to 1.0). On proton-density weighted images, fascicle visualization was significantly improved when high-contrast windowing was used (P=0.04). In conclusion, we found that the popliteomeniscal fascicles are normally seen on MR imaging of the knee when there are no lateral compartment injuries. The fascicles are significantly better visualized on T2-weighted than on proton-density weighted images. Visualization is not significantly affected by the presence of an effusion or slice placement.

The findings in two patients with histologically proven synovial hemangioma of the knee are described. Both cases emphasize the typical appearance of this unusual tumor on magnetic resonance imaging. Additional radiologic findings, such as adjacent osseous involvement, are discussed.