Subchondral insufficiency fracture of the knee: grading, risk factors, and outcome
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To propose an magnetic resonance imaging (MRI) grading system for subchondral insufficiency fracture of the knee (SIFK) to predict outcome and assess risk factors.
Materials and methods
A total of 50 SIFK patients were retrospectively reviewed utilizing two MRI examinations approximately a year apart and compared them with 51 control subjects. A grading system was introduced that classifies lesions as low- vs high-grade. Lesion location 3D dimensions, extent of bone marrow edema (BME), location of meniscal tears and associated extrusion, degree of chondrosis and among other parameters were stratified according to lesion grade and compared with follow-up examinations. Statistical analyses were performed (Pearson’s correlation, binary logistic regression, and Chi-squared analysis).
The majority of SIFK lesions were low-grade (LG; 78%) and most of them (70%) were observed in the medial femoral condyle. Predictor variables comparing low-grade and high-grade SIFK lesions included meniscal tear (p = 0.01), degree of extrusion (p < 0.003), chondrosis (p = 0.01), medial chondrosis grade (p = 0.001), medial femoral condyle (p = 0.01), surface collapse (p < 0.0001), marrow edema improvement (p < 0.0001), first MRI anteroposterior dimension (p = 0.001), transverse dimension (p < 0.001), and ellipsoid volume (p = 0.02). Predictor variables found to be significantly different between controls and patients were meniscal tear (p = 0.024), location of the medial meniscal tear (p < 0.0001), degree of extrusion (p < 0.0001), chondrosis (p < 0.0001), joint effusion (p < 0.0001), Baker’s cyst (p < 0.0001), knee lock (p = 0.03) and buckle (p = 0.01), and history of trauma (p = 0.01).
A SIFK grading system for MRI is introduced. Surrogate markers of high-grade lesions include medial meniscus posterior root tears with associated moderate to severe extrusion, high-grade chondrosis, larger lesion sizes (anteroposterior/transverse), and articular surface collapse. Improvement of BME on follow-up was highly predictive of low-grade disease.
KeywordsInsufficiency fracture of the knee Meniscus Bone marrow edema Chondrosis Spontaneous osteonecrosis of the knee
Bone marrow edema
Medial meniscal tears at the posterior root attachment
Magnetic resonance imaging
Subchondral insufficiency fracture of the knee
Spontaneous osteonecrosis of the knee
- 12.International Cartilage Repair Society (ICRS). ICRS Cartilage Injury Evaluation Package. www.cartilage.org/_files/contentmanagement/ICRS_evaluation.pdf. Developed 27–30 January 2000. https://www.ajronline.org/doi/10.2214/AJR.15.14409.
- 15.Lotke PA, Abend JA, Ecker ML. The treatment of osteonecrosis of the medial femoral condyle. Clin Orthop Relat Res. 1982;(171):109–16.Google Scholar
- 18.Fujita S, Arai Y, Honjo K, Nakagawa S, Kubo TA. Case of spontaneous osteonecrosis of the knee with early and simultaneous involvement of the medial femoral condyle and medial tibial plateau. Case Rep Orthop. 2016;2016:2574975. https://doi.org/10.1155/2016/2574975.CrossRefPubMedPubMedCentralGoogle Scholar
- 30.Koshino T, Okamoto R, Takamura K, Tsuchiya K. Arthroscopy in spontaneous osteonecrosis of the knee. Orthop Clin N Am. 1979;10(3):609–18.Google Scholar