Bucket Handle Tear
A bucket handle tear is a type of vertical longitudinal tear of the meniscus, with displacement of the inner fragment into the intercondylar notch. In other words, the tear widens or gaps. The medial meniscus is more often involved than the lateral meniscus. This type of tear is typically associated with trauma, and is often found in conjunction with ACL tear or insufficiency when medial meniscus is involved, but can occur in isolation.
Bucket Handle Tear: MRI Appearances and Signs
- Decreased meniscal height
- Abnormal or bizarre meniscal shape
- Abrupt meniscal truncation in the coronal projection
- Separation or discontiguity of the meniscus in the coronal projection
- Hypointense fragment within the intercondylar notch in the coronal projection
- Absence of the normal hypointense meniscal triangle in the sagittal projection
- The "double ACL or PCL" sign has been described as a sign of bucket handle tear with a hypointense meniscal fragment lying at the base or underneath the anterior or posterior cruciate ligaments simulating loose body 1
- Double anterior meniscus sign
Bucket handle tears are also described by:
- Vertical longitudinal tear or split, more common in the medial meniscus with a gap usually in meniscus middle one-third
- Decreased meniscal height or volume when "meniscal ghost sign" profound
- "Duplication and meniscus double horn sign"
- Anterior horn "too big" and posterior horn "too small" or meniscus inversion sign 1
Bucket Handle Tear: Treatment
Bucket handle tears are inherently unstable and can cause profound mechanical locking and instability. They are typically addressed through arthroscopy, and can be amenable to repair in younger patients, especially those with concomitant ACL tear. Repair is easier and more feasible when the outer rim is more substantive or wider. Therefore, whenever possible, comment on such width. In cases where the tear cannot be successfully repaired, meniscectomy is performed. Repair of bucket handle tears should be prompt and without delay to ensure likelihood of successful repair.
Bucket Handle Tear: Pitfall: Truncation Tear
A truncation tear involves blunting of the free edge or tip of the meniscus in either the sagittal or, more commonly, the coronal projection [probably just a large radial tear or bucket handle tear].
Bucket Handle Tear: Pearls: Truncation Tear
Truncated meniscus appearance is most typically associated with post-meniscectomy, where the inner edge (white-white zone) is resected during arthroscopy, removing portions of the torn meniscus. This will result in a sharply, clearly delineated blunted appearance of the meniscus posterior/anterior horn or body. In many cases, the entire tear is not debrided or resected, allowing for the outer ⅓ - ⅔ to be left as a remnant, but for these cases there will still be some residual signal in the remnant. Typically, after partial meniscectomy, the meniscus will demonstrate diminished size in addition to the blunted inner edge.
On imaging, this may be mistaken for a complex radial-flap or radial-cleavage tear; history is important to differentiate post-operative changes versus traumatic injury. However, the presence of post-operative arthroscopic artifact, such as scarring in the medial Hoffa’s fat pad, may give clues to suggest arthroscopy in the event that surgical history is not available or provided. Mild truncation from small meniscal resection may be mistaken for traumatic or non-traumatic blunting of the inner edge or meniscal flounce.
Prior imaging is also helpful to determine new tear versus post-operative changes, as the original tear or meniscus appearance can be compared to current imaging for interval changes. It may also be helpful to determine if a new tear of the remnant is present, or if conversion signal from the original tear has worsened or widened to become new pathology.
Bucket Handle Tear: Treatment: Truncation Tear
Truncated menisci typically do not require treatment, as they are remnants of partially resected or debrided menisci from prior injury and stable. However, if a new tear of the remnant is present, intervention may be required for stability of the remnant, usually additional resection or debridement.
Bucket Handle Tear: References
- Pomeranz SJ. Gamuts & Pearls in MRI & Orthopedics. Ohio, The Merten Company, 1997.
Bucket Handle Tear: Example
This 20-year-old male presents with a soccer injury two weeks prior, when he collided with another player. The patient had prior ACL repair. He reports medial pain, swelling and grinding in the knee. MRI study is consistent with bucket handle tear of the medial meniscus.
There are several key findings on MRI. One is the "double PCL sign," which results from the displaced fragment moving into the intercondylar notch, and appears like a second PCL anteroinferior to the PCL; indicated with an arrow on image 1.
Such displacements are often associated with clinical knee locking. Be aware that many patients, especially young ones, confuse locking with catching. We call this catching sensation "pseudolocking." The most common cause of "pseudolocking" is patellofemoral maltracking in a younger patient. True locking, where the knee is actually stuck or "fixed" in partial flexion can also be caused by:
- Trapped, folded or torn cruciate
- Loose cartilage or osseous body (large)
- Unstable cartilage flap
- Severe notch impingement
- Articular fractures
- Massive effusion or hemarthrosis
- Severe hypertrophy fat pad impingement syndrome
Image 1 - T2 FSE Thin Sagittal
The double PCL sign can be mistaken for the anterior meniscofemoral ligament (ligament of Humphrey); it can be differentiated with correlating findings for meniscal pathology or by following the course of the ligament. “Double PCLs” are thicker than Humphrey ligaments.
Another key to the diagnosis is the diminished substance or volume of the outer peripheral one third of the meniscus with truncation of the inner edge on coronal images. Small size of the anterior and posterior horns on sagittal images is the third key finding. There will be meniscal-like signal as a fragment in the intercondylar notch. If the fragment flips or displaces more anteriorly an increase in size may be seen in the anterior horn and appears as "double anterior horn" or "double meniscus sign". The duplicated or "double" meniscus sign is more common lateral than medial. In this case, the native anterior horn is actually displaced anteriorly (image 2, arrow one) and the fragment is in the usual location of the anterior horn (image 2, arrow two). The posterior horn is diminished in size (image 2, arrow three). A third key sign for the most common type of bucket handle tear is separation of the meniscus coronally into "two pieces". (image 3, arrows 4 and 5). This is known as the "split meniscus sign".
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Image 2 - T2 Sagittal Fat Sat Image 3 - T2 Coronal Fat Sat
Bucket handle tears can be correlated on axial imaging as well; meniscal signal will be present along the intercondylar notch (will look like a circular rather than C-shaped meniscus), or clearly defined fragment may be present. However, due to variations in slice thickness, it may not always be visualized. Finally, on a sagittal view, the anterior horn medially and laterally should never be shorter or “less tall” than the posterior meniscus. If it is, in an unoperated knee, consider "meniscus inversion sign" of a bucket handle tear. However, the most common cause of the “meniscus inversion sign” is meniscectomy.
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