Consecutive Knee Magnetic Resonance Imaging Research Articles

Association Between MRI-Based Tibial Slope Measurements and Mucoid Degeneration of the Anterior Cruciate Ligament: A Propensity Score-Matched Case-Control Study.

Background:The cause of mucoid degeneration (MD) of the anterior cruciate ligament (ACL), which is commonly observed on magnetic resonance imaging (MRI) of patients with knee pain, has yet to be elucidated. Despite the limited evidence on the relationship between ACL lesions (injury and MD) and tibial morphologic features (ie, posterior tibial slope), the potential association between the presence of ACL MD and medial and lateral tibial slope (MTS and LTS) has not been well-established.Purpose:To investigate whether MTS and LTS measurements are associated with the presence of ACL MD.Study Design:Cross-sectional study; Level of evidence, 3.Methods:Consecutive knee MRI examinations of patients referred by an orthopaedic surgeon for potential internal joint derangements were identified within a 4-year period. The presence of ACL MD and the MTS/LTS values were assessed by independent expert observers in consensus in a blinded fashion. From 413 consecutive knee MRI scans, a sample of 80 knees, including 32 knees with ACL MD (cases) and 48 knees with normal ACL (controls), were selected using propensity score matching method for age, sex, body mass index, and presence of severe medial tibiofemoral compartment cartilage damage. The association between ACL MD and MTS/LTS was evaluated using conditional regression models.Results:Knees with ACL MD had higher values of LTS (mean ± SD, 7.18° ± 3.58°) in comparison with control knees (5.32° ± 3.35°). Conditional regression analysis revealed a significant association between LTS measurements (not MTS) and ACL MD; every 1° increase in LTS was associated with a 17% (95% CI, 1%-35%) higher probability of having ACL MD.Conclusion:Excessive LTS was associated with the presence of ACL MD, independent of participants’ age, sex, BMI, and cartilage damage severity.

MRI analysis of extra-capsular ganglia at the gastrocnemius origin and their association with osteoarthritis

To evaluate the prevalence, clinical relevance, and magnetic resonance imaging (MRI) features of extra-capsular ganglia at the gastrocnemius origin and to assess their association with internal derangement and osteoarthritis of the knee. One hundred consecutive knee MRI examinations, obtained within a 6-month period from patients with no history of recent knee trauma, recent injections, inflammatory arthritis, infection, or tumours, were evaluated retrospectively for the presence of ganglia at the gastrocnemius origin. The lesions were divided into two groups: an intra-capsular and an extra-capsular group. Cyst morphology (size, shape, and internal septa), internal derangement of the knee (cartilage lesion, cruciate ligament injury, meniscal tear, and corner injury on MRI, and osteoarthritis of the knee on radiographs) were evaluated. The chi-square, Fisher's exact, and t-tests were used to compare the two groups, in addition to multivariate stepwise logistic regression analysis. Thirty-nine ganglia with an extra-capsular location were identified on 100 knee MRI (39 %). Rounded shape and internal septa were more common in the extra-capsular than in the intra-capsular group (p<0.001). Frequencies of high-grade cartilage, meniscal tear, and high-grade osteoarthritis significantly differed between the groups (p≤0.038). In multivariate analysis, the only significant association was between high-grade osteoarthritis and the extra-capsular group. Extra-capsular ganglia at the gastrocnemius origin were not uncommon on knee MRI and had features typical of ganglia found at other sites. High-grade osteoarthritis was significantly associated with extra-capsular ganglia.

Patellofemoral joint is an under reported joint in MRI knee - A retrospective, cross-sectional study.

BackgroundPatellofemoral joint (PFJ) pathology accounts for upto 40% of cases of knee pain. It has been suggested that PFJ pathology may be underreported in Magnetic Resonance Imaging (MRI) Knee reports. The objective of this study was to elucidate whether PFJ was reported in MRI knee reports at our institution.Materials and methodsA retrospective review of 103 consecutive Knee MRIs over a 2-month period was performed by an author, blinded to the reports, at our institution. We analysed whether PFJ was mentioned in MRI knee reports and whether any significant PFJ pathology was present in the scans of this cohort. Images were also reviewed for any underlying causes of PFJ pathology such as trochlear dysplasia (TD) that can result in patellar instability or maltracking.ResultsPFJ was not mentioned in 79/103 cases (77%). 24 cases had trochlear dysplasia. There was no association between PFJ reporting and trochlear dysplasia (p value = 0.50).ConclusionPFJ is not mentioned in the majority of Knee MRI reports. PFJ pathology is an important cause of anterior knee and should be reported.

Physician provider type influences utilization and diagnostic utility of magnetic resonance imaging of the knee.

Magnetic resonance imaging of the knee is expensive and is neither needed nor useful for all patients presenting with knee pain. Our objective was to determine the completeness of evaluation prior to ordering magnetic resonance imaging of the knee correlated to the ordering providers' postgraduate medical training and the rate of positive findings on the subsequent magnetic resonance imaging. Six hundred consecutive knee magnetic resonance images were reviewed, including 200 consecutive knee magnetic resonance imaging examinations from each of three provider types: orthopaedic surgeons, non-surgical physicians with sports medicine training, and primary care providers. Positive findings on magnetic resonance imaging were recorded as well as a history of present illness, a physical examination, and radiographs made prior to ordering magnetic resonance imaging of the knee. Patient and injury factors were recorded. Differences in patient factors, evaluation before magnetic resonance imaging, and positive findings were examined. A modified Poisson regression approach was used to determine predictors of a proper evaluation before magnetic resonance imaging and positive findings on knee magnetic resonance imaging. Orthopaedists and non-surgical sports physicians were significantly more likely to document a physical examination, to evaluate radiographs made prior to ordering a magnetic resonance image, and to identify positive findings on the magnetic resonance image (all p < 0.001). In multivariate models, orthopaedists were more likely to document a history of present illness (relative risk, 1.05; p = 0.043). Compared with primary care physicians, a physical examination was more likely to be documented by both non-surgical sports medicine physicians (relative risk, 1.61; p < 0.001) and orthopaedists (relative risk, 1.60; p < 0.001) and positive magnetic resonance imaging findings were more likely to be found by non-surgical sports medicine physicians (relative risk, 1.41; p = 0.012) and by orthopaedists (relative risk, 1.44, p = 0.009). Other independent predictors of a magnetic resonance imaging study with positive findings were the presence of an acute injury by history (relative risk, 2.04; p < 0.001) and younger age (relative risk, 0.99; p = 0.021). Orthopaedists and non-surgical sports physicians are more likely to perform and to document a complete evaluation prior to ordering a knee magnetic resonance image with a positive finding. More musculoskeletal training may be useful to enable primary care physicians to use magnetic resonance imaging of the knee in a more efficient manner.

The Aberrant Anterior Tibial Artery

Background Injury of a popliteal fossa artery during orthopaedic knee surgery is very rare but has serious consequences. The risk of vascular trauma during orthopaedic procedures may be increased when there is abnormal branching of the popliteal artery with an aberrant anterior tibial artery originating above the popliteus muscle and coursing between the posterior tibial cortex and ventral margin of the popliteus muscle. Preoperative identification of this anatomical variant may help avoid these injuries. Hypothesis The aberrant anterior tibial artery is present in a substantial portion of the population and can be visualized by magnetic resonance imaging. Study Design Cross-sectional study; Level of evidence, 3. Methods Retrospective review of 1116 consecutive knee magnetic resonance imaging studies was performed to evaluate the prevalence of an aberrant anterior tibial artery. Images were reviewed by 3 musculoskeletal radiologists. Results The aberrant anterior tibial artery was present in 23 of 1116 extremities for a prevalence of 2.1 %. The aberrant artery was most easily identified on axial and sagittal magnetic resonance imaging scans. Conclusion The aberrant anterior tibial artery is a relatively common normal variant, and magnetic resonance is an excellent modality for detection of the artery close to the posterior joint capsule and tibial cortex. Clinical Relevance The anatomy suggests the aberrant anterior tibial artery may be at greater risk of injury in orthopaedic procedures such as high tibial osteotomy, revision total knee arthroplasty, lateral meniscal repair, posterior cruciate ligament reconstruction, and screw fixation for tibial tubercle osteotomy. Careful inspection of preoperative magnetic resonance imaging studies may alert the surgeon to the presence of this anatomical variant.

MRI findings in bipartite patella

Bipartite patella is a known cause of anterior knee pain. Our purpose was to detail the magnetic resonance imaging (MRI) features of bipartite patella in a retrospective cohort of patients imaged at our institution. MRI exams from 53 patients with findings of bipartite patella were evaluated to assess for the presence of bone marrow edema within the bipartite fragment and for the presence of abnormal signal across the synchondrosis or pseudarthrosis. Any other significant knee pathology seen at MRI was also recorded. We also reviewed 400 consecutive knee MRI studies to determine the MRI prevalence of bipartite patella. Of the 53 patients with bipartite patella 40 (75%) were male; 35 (66%) had edema within the bipartite fragment. Of the 18 with no edema an alternative explanation for knee pain was found in 13 (72%). Edema within the bipartite fragment was the sole finding in 26 of 53 (49%) patients. Bipartite patella was seen in 3 (0.7%) of 400 patients. In patients with bipartite patella at knee MRI, bone marrow edema within the bipartite fragment was the sole finding on knee MRI in almost half of the patients in our series.

The clinical significance of anterior horn meniscal tears diagnosed on magnetic resonance images.

We assessed the accuracy of magnetic resonance imaging in detecting clinically significant lesions of the anterior horn of the meniscus by reviewing 947 consecutive knee magnetic resonance imaging reports. Of these, 76 (8%) indicated a tear of the anterior horn of the medial or lateral meniscus. Thirty-one of these 76 patients underwent a subsequent arthroscopic examination, and their operative reports were reviewed. The 45 patients who were not examined arthroscopically were contacted and interviewed for clinical follow-up. Among the 31 patients who underwent arthroscopic examination, 8 anterior horn tears were noted in the predicted area (26% true-positive results), 23 patients had intact anterior horns (74% false-positive results), and 18 had normal intact menisci in all zones. Of the 45 patients who did not undergo arthroscopic surgery, 6 had isolated anterior horn tears reported on magnetic resonance imaging, and 5 of the 6 were asymptomatic at follow-up. The other 39 patients had multiple pathologic conditions noted on the magnetic resonance imaging report and continued to report knee pain at the follow-up interview. Increased signal intensity at the anterior horn of the meniscus seen on magnetic resonance imaging commonly does not represent a clinically significant lesion. We recommend correlation with the physical examination when interpreting this "positive" finding on knee magnetic resonance imaging examinations.