To investigate if MRI findings of the thickness of synovitis could be used as criteria for the indications of knee replacement.

Thirty-one patients with end-stage knee osteoarthritis (OA) were selected and received the following examinations: (1) noninvasive MRI evaluation for grading the synovial thickness of the investigated sites (i.e., medial and lateral parapatellar recesses, and medial and lateral suprapatellar pouches; synovitis was categorized into grade zero to three on the basis of the thickness); (2) determination of knee-joint pain scores (visual analogue scale, VAS score) and functional scores Western Ontario and McMaster Univerisities Osteoarthrifis index, WOMAC) before total knee arthroplasty (TKA). Pearson’s linear test or Spearman rank test was used to analyze the correlation between synovial thickness and WOMAC OA index, and VAS score.

Statistical analysis revealed no significant differences in MRI synovial thickening grade across the different regions of the knee.No correlation existed between the grades of MRI-determined thickness for synovitis and knee joint function scores with pain score (rs=0.17, P>0.05; rs=0.32, P >0.05), as well as no correlation existed between the different regions of the knee and the above factors respectively.

The grade of MRI-determined thickness of synovitis shows no correlation with the subjective scores in the patients with end-stage knee OA, thus the grades of MRI-determined thickness cannot be used as criteria for knee joint replacement indications, and further study on the relation among MRI, VAS and WOMAC scores is still warranted.