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Repeat Tear of Postoperative Meniscus: Potential MR Imaging Signs

¹ Department of Radiology, Thomas Jefferson University Hospital, 132 S 10th St, 1096 Main Bldg, Philadelphia, PA 19107 (P.S.L., M.E.S., M.B., V.G., P.P.K., R.M.S., L.P.)
² Orthopedic Consultants, Lancaster, Pa (M.O.)
³ Orthopedic Associates, Langhorne, Pa (W.J., B.A.).

View larger version (10K): [in a new window]   Figure 1. Intrameniscal signal intensity conversion. Diagrams illustrate the potential of creating an intrasubstance grade 3 signal intensity abnormality after meniscectomy. A, torn meniscus. The dotted lines show the planned incision. The surgeon resects the torn portion of the virgin meniscus after probing it. This resected fragment usually does not contain the entire linear area of abnormal signal intensity (straight line) seen on the MR images. B, Untorn postoperative meniscus. A grade 3 signal intensity abnormality now extends to the articular surface and mimics a tear. (Modified, with permission, from reference 4.)

View larger version (10K): [in a new window]   Figure 2. Possible postoperative meniscal shapes of the posterior horn, as seen on sagittal images. A, Diagram shows meniscus after 0%–25% meniscal resection, with reshaping of the inner margin. The inner margin appears blunted. B, Diagram shows meniscus after approximately 50% meniscal resection. C, Diagram shows meniscus after approximately 75% meniscal resection. D, Diagram shows meniscal regrowth after partial resection. The meniscus has an irregular, wavy contour with a slightly higher signal intensity (stippling) than that of the virgin meniscus on images obtained with a proton-density–weighted MR sequence.

View larger version (143K): [in a new window]   Figure 3a. Proved repeat tear of the medial meniscus in a 46-year-old man. The tear is documented as an intrameniscal linear area of abnormal signal intensity extending to the articular surface and as fluid within the line (TP repeat meniscal tear). (a) Sagittal proton-density–weighted fat-suppressed image (1,133/20) shows an oblique linear area of abnormal signal intensity (arrow) extending to the undersurface of the meniscus. (b) Sagittal T2-weighted fast SE fat-suppressed image (4,500/80) shows fluid within the line (straight arrow) and a moderate joint effusion (curved arrow).

View larger version (179K): [in a new window]   Figure 3b. Proved repeat tear of the medial meniscus in a 46-year-old man. The tear is documented as an intrameniscal linear area of abnormal signal intensity extending to the articular surface and as fluid within the line (TP repeat meniscal tear). (a) Sagittal proton-density–weighted fat-suppressed image (1,133/20) shows an oblique linear area of abnormal signal intensity (arrow) extending to the undersurface of the meniscus. (b) Sagittal T2-weighted fast SE fat-suppressed image (4,500/80) shows fluid within the line (straight arrow) and a moderate joint effusion (curved arrow).

View larger version (180K): [in a new window]   Figure 4a. Proved repeat tear of the medial meniscus in a 49-year-old man. The tear is documented as an intrameniscal linear area of abnormal signal intensity extending to the articular surface and as fluid within the line (TP repeat meniscal tear). (a) Sagittal proton-density–weighted fat-suppressed image (1,133/20) shows a linear area of abnormal signal intensity extending from the superior (double arrows) to the inferior (single arrow) articular surfaces of the meniscus. (b) Sagittal T2-weighted fast SE fat-suppressed image (4,488/100) shows fluid within the line (straight arrows) and a small joint effusion. Subtle femoral cartilage loss (curved arrows) also is seen.

View larger version (173K): [in a new window]   Figure 4b. Proved repeat tear of the medial meniscus in a 49-year-old man. The tear is documented as an intrameniscal linear area of abnormal signal intensity extending to the articular surface and as fluid within the line (TP repeat meniscal tear). (a) Sagittal proton-density–weighted fat-suppressed image (1,133/20) shows a linear area of abnormal signal intensity extending from the superior (double arrows) to the inferior (single arrow) articular surfaces of the meniscus. (b) Sagittal T2-weighted fast SE fat-suppressed image (4,488/100) shows fluid within the line (straight arrows) and a small joint effusion. Subtle femoral cartilage loss (curved arrows) also is seen.

View larger version (110K): [in a new window]   Figure 5a. Proved repeat meniscal tear at the site of initial surgery in a 52-year-old man (TP repeat meniscal tear). (a) Initial sagittal proton-density–weighted fat-suppressed image (1,033/20) shows a mild irregularity (arrow) at the undersurface of the meniscus that was a tear at surgery. (b) Initial sagittal T2-weighted fast SE fat-suppressed image (4,233/105) shows mild irregularity at the undersurface but no fluid within the line. (c) Sagittal proton-density–weighted fat-suppressed image (1,183/20) and (d) corresponding sagittal T2-weighted fast SE fat-suppressed image (4,233/100) obtained 24 months after a and b. c shows a linear area of abnormal signal intensity (arrow) extending to the undersurface of the meniscus. d shows fluid within the line (arrow), indicating a tear that has extended from the initial meniscal surgical site.

View larger version (112K): [in a new window]   Figure 5b. Proved repeat meniscal tear at the site of initial surgery in a 52-year-old man (TP repeat meniscal tear). (a) Initial sagittal proton-density–weighted fat-suppressed image (1,033/20) shows a mild irregularity (arrow) at the undersurface of the meniscus that was a tear at surgery. (b) Initial sagittal T2-weighted fast SE fat-suppressed image (4,233/105) shows mild irregularity at the undersurface but no fluid within the line. (c) Sagittal proton-density–weighted fat-suppressed image (1,183/20) and (d) corresponding sagittal T2-weighted fast SE fat-suppressed image (4,233/100) obtained 24 months after a and b. c shows a linear area of abnormal signal intensity (arrow) extending to the undersurface of the meniscus. d shows fluid within the line (arrow), indicating a tear that has extended from the initial meniscal surgical site.

View larger version (87K): [in a new window]   Figure 5c. Proved repeat meniscal tear at the site of initial surgery in a 52-year-old man (TP repeat meniscal tear). (a) Initial sagittal proton-density–weighted fat-suppressed image (1,033/20) shows a mild irregularity (arrow) at the undersurface of the meniscus that was a tear at surgery. (b) Initial sagittal T2-weighted fast SE fat-suppressed image (4,233/105) shows mild irregularity at the undersurface but no fluid within the line. (c) Sagittal proton-density–weighted fat-suppressed image (1,183/20) and (d) corresponding sagittal T2-weighted fast SE fat-suppressed image (4,233/100) obtained 24 months after a and b. c shows a linear area of abnormal signal intensity (arrow) extending to the undersurface of the meniscus. d shows fluid within the line (arrow), indicating a tear that has extended from the initial meniscal surgical site.

View larger version (94K): [in a new window]   Figure 5d. Proved repeat meniscal tear at the site of initial surgery in a 52-year-old man (TP repeat meniscal tear). (a) Initial sagittal proton-density–weighted fat-suppressed image (1,033/20) shows a mild irregularity (arrow) at the undersurface of the meniscus that was a tear at surgery. (b) Initial sagittal T2-weighted fast SE fat-suppressed image (4,233/105) shows mild irregularity at the undersurface but no fluid within the line. (c) Sagittal proton-density–weighted fat-suppressed image (1,183/20) and (d) corresponding sagittal T2-weighted fast SE fat-suppressed image (4,233/100) obtained 24 months after a and b. c shows a linear area of abnormal signal intensity (arrow) extending to the undersurface of the meniscus. d shows fluid within the line (arrow), indicating a tear that has extended from the initial meniscal surgical site.

View larger version (80K): [in a new window]   Figure 6. Abnormal meniscal morphology in a 34-year-old woman with intractable knee pain due to severe tricompartmental osteoarthritis; the patient had not undergone prior meniscal resection (FP finding). Sagittal proton-density–weighted fat-suppressed image (1,000/20) shows that the anterior horn of the medial meniscus (arrow) is diminutive.

View larger version (63K): [in a new window]   Figure 7a. Proved meniscal repeat tear at the anterior horn of the lateral meniscus in a 30-year-old man (FN finding). (a) Sagittal proton-density–weighted fat-suppressed image (1,183/20) shows an abnormal shape of the anterior horn and a likely postoperative appearance but no linear area of abnormal signal intensity. The linear area of abnormal signal intensity extending to the articular surface of the posterior horn (arrow) was due to prior meniscal resection, but no repeat tear was seen at second surgery. (b) Coronal proton-density–weighted fat-suppressed image (1,000/20) shows an abnormal shape of the anterior horn of the lateral meniscus (arrow).

View larger version (55K): [in a new window]   Figure 7b. Proved meniscal repeat tear at the anterior horn of the lateral meniscus in a 30-year-old man (FN finding). (a) Sagittal proton-density–weighted fat-suppressed image (1,183/20) shows an abnormal shape of the anterior horn and a likely postoperative appearance but no linear area of abnormal signal intensity. The linear area of abnormal signal intensity extending to the articular surface of the posterior horn (arrow) was due to prior meniscal resection, but no repeat tear was seen at second surgery. (b) Coronal proton-density–weighted fat-suppressed image (1,000/20) shows an abnormal shape of the anterior horn of the lateral meniscus (arrow).

View larger version (125K): [in a new window]   Figure 8a. Proved meniscal fraying rather than repeat tear in a 22-year-old woman (FP meniscal tear at site of original surgery). (a) Initial sagittal proton-density–weighted fat-suppressed image (1,066/20) shows an oblique linear area of abnormal signal intensity (arrows) extending to the undersurface of the meniscus. (b) Initial sagittal T2-weighted fast SE fat-suppressed image (4,233/100) shows no fluid within the line. (c) Sagittal proton-density–weighted fat-suppressed image (1,133/20) obtained 7 months after a shows a more extensive linear area of abnormal signal intensity (arrows) extending to the superior and inferior articular surfaces of the meniscus. (d) Corresponding sagittal T2-weighted fast SE fat-suppressed image (4,233/100) shows faint fluid within the line (arrow) extending to the superior articular surface of the meniscus that was not present on the initial MR study. At surgery, only meniscal fraying was seen.

View larger version (138K): [in a new window]   Figure 8b. Proved meniscal fraying rather than repeat tear in a 22-year-old woman (FP meniscal tear at site of original surgery). (a) Initial sagittal proton-density–weighted fat-suppressed image (1,066/20) shows an oblique linear area of abnormal signal intensity (arrows) extending to the undersurface of the meniscus. (b) Initial sagittal T2-weighted fast SE fat-suppressed image (4,233/100) shows no fluid within the line. (c) Sagittal proton-density–weighted fat-suppressed image (1,133/20) obtained 7 months after a shows a more extensive linear area of abnormal signal intensity (arrows) extending to the superior and inferior articular surfaces of the meniscus. (d) Corresponding sagittal T2-weighted fast SE fat-suppressed image (4,233/100) shows faint fluid within the line (arrow) extending to the superior articular surface of the meniscus that was not present on the initial MR study. At surgery, only meniscal fraying was seen.

View larger version (131K): [in a new window]   Figure 8c. Proved meniscal fraying rather than repeat tear in a 22-year-old woman (FP meniscal tear at site of original surgery). (a) Initial sagittal proton-density–weighted fat-suppressed image (1,066/20) shows an oblique linear area of abnormal signal intensity (arrows) extending to the undersurface of the meniscus. (b) Initial sagittal T2-weighted fast SE fat-suppressed image (4,233/100) shows no fluid within the line. (c) Sagittal proton-density–weighted fat-suppressed image (1,133/20) obtained 7 months after a shows a more extensive linear area of abnormal signal intensity (arrows) extending to the superior and inferior articular surfaces of the meniscus. (d) Corresponding sagittal T2-weighted fast SE fat-suppressed image (4,233/100) shows faint fluid within the line (arrow) extending to the superior articular surface of the meniscus that was not present on the initial MR study. At surgery, only meniscal fraying was seen.

View larger version (124K): [in a new window]   Figure 8d. Proved meniscal fraying rather than repeat tear in a 22-year-old woman (FP meniscal tear at site of original surgery). (a) Initial sagittal proton-density–weighted fat-suppressed image (1,066/20) shows an oblique linear area of abnormal signal intensity (arrows) extending to the undersurface of the meniscus. (b) Initial sagittal T2-weighted fast SE fat-suppressed image (4,233/100) shows no fluid within the line. (c) Sagittal proton-density–weighted fat-suppressed image (1,133/20) obtained 7 months after a shows a more extensive linear area of abnormal signal intensity (arrows) extending to the superior and inferior articular surfaces of the meniscus. (d) Corresponding sagittal T2-weighted fast SE fat-suppressed image (4,233/100) shows faint fluid within the line (arrow) extending to the superior articular surface of the meniscus that was not present on the initial MR study. At surgery, only meniscal fraying was seen.