MR Assessment of Distribution and Amount of Joint Effusion in Patients with Traumatic Knee Joint Disorders

PURPOSE: To clarify the distribution of joint effusion, and the relationship between type of injury andamount of joint effusion seen in traumatic knee joint magnetic resonance imaging (MRI). MATERIALS AND METHODS: Weretrospectively reviewed the MR images of 400 patients with traumatic knee joint effusion. The knee joint spacewas divided into four compartments: central portion (para-ACL, para-PCL), suprapatellar pouch, posterior femoralrecess, and subpopliteal recess, and we then compared the amount and distribution of effusion. For statisticalanalysis, the chi-square test was used. RESULTS: Among 400 MRI examinations of joint effusion, 383 knees (96%)showed homogeneous low intensity on T1-weighted images, and - except for ten cases of fluid-fluid levels-homogeneous high intensity on T2-weighted images. Knee joint effusion was clearly shown to be distributed mainlyin the suprapatellar pouch (345, 86%), followed by the central posterior femoral recess, and the subpoplitealrecess (p<0.001). Extensive joint effusion was less frequently found in the normal group, but was occasionallyfound in the combined injury group (p<0.001). The relationship between amount of joint effusion and type ofinjury was statistically significant (p<0.001), except in the case of medial and lateral collateral ligamentinjury. CONCLUSIONS: The distribution of joint effusion in patients with traumatic knee disorders is a reflectionof anatomic communication, and whether the amount of joint effusion was small or large depended on the anatomicallocation and type of injury.

A Relationship Between Amount of Joint Effusion, Disk Displacement and Presence of Pain in theTemporomandibular Joint: MR Imaging

PURPOSE: To correlate MR findings of amount of temporomandibular joint effusion with joint pain and disk displacement. MATERIALS AND METHODS: In 57 patients, 114 temporomandibular joints with symptoms of disorder(presence of clinical pain) were imaged. Closed and open mouth sagittal spin echo (SE) T1-weighted images (WI) and fast spin echo (FSE) T2-WI were obtained. We classified the amount of joint effusion into grades. Joint effusion was classified as either Grade I, II or III, as follours : in sagittal FSE T2-WI, a long diameter of joint effusion shorter than 1/3 of the diameter of the convex margin of temporal eminence was grade I; longer than 2/3 was grade III; between grade I and III was grade II. Disk displacement was classified as either with or without reduction in the open mouth position. These findings were correlated with one another and statistically analyzed. RESULTS: In 29 cases with joint pain (37%) and in 34 cases without pain (63%) there was no evidence of joint effusion; there were, however, more grade I joint effusion cases with pain (14 ; 60.9%) than without pain (9 : 39.1%). Cases of joint pain increased in proportion to grade of joint effusion, which was statistically significant (p<0.05). In joints without disk displacement, the largest grouping was that which showed no effusion (39 ; 72.2%) ; no joints showed grade III effusion. Cases of joint effusion decreased in proportion to grade of effusion. In joints with disk displacement, cases of joint effusion tended to increase in proportion to the grade of effusion. CONCLUSION: MR findings of amount of temporomandibular joint effusion correlate with joint pain and anterior disk displacement.