Bucket handle tear

A bucket-handle tear of the knee is a specific type of meniscal injury characterized by a longitudinal tear of the medial or lateral meniscus, where a displaced inner fragment resembles the appearance of a "bucket handle". This displaced meniscal fragment often remains attached at the anterior and posterior horns but dislocates into the intercondylar notch of the knee joint. Such injuries can cause mechanical symptoms, including locking and restricted movement of the knee.

Anatomy

The knee joint contains two crescent-shaped fibrocartilaginous structures, the menisci (medial and lateral), which serve as shock absorbers and stabilize the joint during movement. Each meniscus has an outer vascular zone (red-red zone), which has a good blood supply and healing potential as well as a central avascular zone (white-white zone), which has limited healing capability.

The medial meniscus is more prone to injury due to its firm attachment to the joint capsule and limited mobility. The lateral meniscus is more mobile and less frequently injured.

Pathophysiology

A bucket-handle tear occurs when a significant longitudinal tear develops, often as a result of trauma or excessive twisting forces applied to the knee. The displaced fragment can flip into the intercondylar notch, impeding normal joint motion. The injury is most commonly seen in:

• Young, active individuals: Especially those engaged in sports like soccer, basketball, or skiing.
• Traumatic events: Sudden twisting or pivoting movements with the knee in flexion and rotation.
• Degenerative knees: Less commonly, a bucket-handle tear can occur in older individuals with preexisting meniscal degeneration.

The injury frequently occurs in conjunction with anterior cruciate ligament (ACL) tears.

Clinical presentation

Patients with a bucket-handle tear typically present with the following symptoms:

• Knee locking: A classic symptom where the displaced fragment physically blocks full extension of the knee
• Pain: Sudden, sharp pain localized to the joint line
• Swelling: Acute hemarthrosis (blood in the joint) due to associated trauma
• Mechanical symptoms: Popping, clicking, or catching during movement
• Reduced range of motion: Especially inability to fully extend the knee (extension block)

The patient may report a history of a twisting injury or sports-related trauma

Diagnosis

Diagnosis of a bucket-handle tear is based on a combination of clinical examination and imaging studies:

Physical examination

• Joint line tenderness (medial or lateral, depending on the location of the tear)
• Positive McMurray test: Pain or clicking when the knee is rotated while flexed
• Loss of knee extension (locked knee)

Imaging

• Magnetic Resonance Imaging (MRI): The gold standard for diagnosing bucket-handle tears. Key findings on MRI include:
• Double PCL sign: The displaced meniscal fragment mimics the appearance of a second posterior cruciate ligament (PCL) on sagittal images.
• Flipped meniscus appearance: The displaced fragment creates an abnormal signal within the joint in sagittal view.

Plain Radiographs (X-rays): While X-rays cannot visualize meniscal tears, they may rule out bony injuries. Occasionally, a joint effusion may be observed.

Treatment

Management of bucket-handle tears is primarily surgical, as these tears often cause mechanical symptoms and are unlikely to heal on their own due to the displacement of the meniscal fragment. Treatment approaches include:

Arthroscopic Surgery

• Meniscal repair: Preferred for young patients or those with tears in the vascular (red-red) zone, which has healing potential. Arthroscopic sutures are used to repair the torn meniscus.
• Partial meniscectomy: If the tear is in a non-repairable location (white-white zone) or the meniscal tissue is extensively damaged, the displaced fragment may be excised.

Rehabilitation

Postoperative care includes:

• Physical therapy: To restore range of motion, strength, and stability.
• Weight-bearing restrictions: Gradual progression of weight-bearing activities based on surgical repair.

Return to sports is usually permitted after 4–6 months, depending on the success of meniscus repair and concomitant injuries (e.g., ACL tear).

References