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[Can MRI determine whether acute or chronic processes predisposing conditions are present in spontaneous
M F Cegarra Navarro1, M Martínez Fernández, A Blanco Barrio
1Servicio de Radiodiagnóstico, Hospital General Universitario Morales Meseguer, Murcia, España. paquicegarra@hotmail.com
Objective:
To analyze possible underlying causes of spontaneous osteonecrosis of the knee in adults in function of the lesion's behavior on magnetic resonance imaging (MRI): acute lesion (insufficiency fractures) or chronic lesion (osteoarthritic degeneration).
Material And Methods:
We retrospectively evaluated knee MRI studies in 48 patients who fulfilled criteria for spontaneous osteonecrosis. A total of 51 subchondral lesions were included and classified in two groups: those in which linear images were present (Group A) and those in which linear images were not present (Group B). We recorded the location and size of the lesions, their signal intensity, their relation with bone edema, ipsilateral meniscal tear and abnormalities in the adjacent cartilage, as well as the presence of osteoarthritis.
Results:
We studied 28 men and 20 women (mean age, 55.1+/-18.0 years). Linear images were present in 58.5% of lesions (group A) and absent in 41.2% (group B). The most common location in both groups was the internal femoral condyle (56.7% in group A and 52.4% in group B), and 88.2% of lesions were hypointense on T1-weighted and fat suppressed proton density sequences. The mean size of the anteroposterior and transversal diameters was 11.9+/-3.6 x 9.4+/-3.9 mm in group A and 10.9+/-5.1 x 10.5+/-4.5 mm in group B. The predominant bone edema was severe (grade 2-3) in group A and mild (grade 0-1) in group B (p=0.033). Defects in the cartilage ipsilateral to the subchondral lesion were more common in group B than in group A, although this difference was not significant (76.2% and 56.7%, respectively; p=0.33). The frequency of ipsilateral meniscal tear was similar in the two groups (56.7% in group A and 57.1% in group B; p=0.97).
Conclusion:
Knowing the MRI findings for spontaneous osteonecrosis and evaluating other data (type of lesion, bone edema, meniscal tear, and ipsilateral cartilage defects) can help determine the primary predisposing process. Linear lesions might be related to an acute process (insufficiency fractures) and non-linear lesions might be related to a chronic process (osteoarthritis).
Insights
Magnetic resonance imaging (MRI) can differentiate spontaneous osteonecrosis of the knee by identifying linear lesions as acute insufficiency fractures and non-linear lesions as chronic osteoarthritis. This distinction aids in determining the primary cause of knee osteonecrosis.
Area of Science:
- Orthopedic imaging
- Radiology
- Knee joint pathology
Context:
- Spontaneous osteonecrosis of the knee (SONK) is a debilitating condition.
- Differentiating between acute insufficiency fractures and chronic osteoarthritis is crucial for effective treatment.
- Magnetic resonance imaging (MRI) is a key diagnostic tool in evaluating knee pathologies.
Purpose:
- To analyze the underlying causes of spontaneous osteonecrosis of the knee based on MRI findings.
- To correlate lesion characteristics on MRI with acute (insufficiency fractures) versus chronic (osteoarthritic degeneration) processes.
- To investigate the relationship between MRI features, bone edema, meniscal tears, and cartilage defects in SONK.
Summary:
- A retrospective analysis of 51 knee MRI studies in 48 patients with spontaneous osteonecrosis was conducted.
- Lesions were classified into Group A (linear images present) and Group B (linear images absent).
- Linear lesions (Group A) were associated with more severe bone edema, suggesting an acute process (insufficiency fractures), while non-linear lesions (Group B) showed less edema and were potentially linked to chronic osteoarthritis.
Impact:
- MRI findings, including lesion morphology and associated bone edema, can help differentiate between acute insufficiency fractures and chronic osteoarthritis in spontaneous osteonecrosis of the knee.
- This differentiation aids clinicians in identifying the primary predisposing process for SONK.
- Improved diagnostic accuracy can lead to more targeted and effective treatment strategies for patients with knee osteonecrosis.
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