Bucket-Handle Meniscal Tear

Bucket handle meniscal tear is a large longitudinal vertical tear of the meniscus in which the inner fragment (the handle) displaces into the intercondylar notch while the peripheral rim stays attached at the anterior and posterior horns. It accounts for about 10% of meniscal tears and is more common on the medial side (about 3 to 1).

It follows a twisting injury of the flexed, weight bearing knee, usually in young active men, and is common with anterior cruciate ligament rupture (up to 30 to 50%). Degenerative bucket handle tears occur in older adults after minor trauma.

The displaced fragment blocks full extension and produces a locked knee. Complications are persistent locking, osteoarthritis (accelerated by loss of meniscus), chondral injury, recurrent tear, and, after repair, failure to heal (about 15 to 25%).

Pathophysiology.

A rotational force with axial load across the flexed knee traps the meniscus between the femoral condyle and tibial plateau and tears it longitudinally. The peripheral third of the meniscus (the red zone) has a blood supply and can heal after repair, the middle third (red white zone) has a variable supply, and the inner third (white zone) is avascular. Bucket handle tears often involve the red red or red white zones, so they are repairable.

Acute knee pain and swelling (haemarthrosis if the red zone is torn, or effusion within hours), and a mechanically locked knee with loss of full extension (a springy block with a 10 to 30 degree extension deficit). Pain on the joint line, particularly with flexion and rotation.

• Joint line tenderness.
• McMurray test (pain and click on flexion and rotation), Thessaly test (weight bearing rotation at 20 degrees of flexion), and Apley test, though these are often limited by the locked knee.
• Examine for associated ligament injury (Lachman, anterior and posterior drawer, varus and valgus stress, pivot shift).

• Radiographs: weight bearing anteroposterior, lateral, skyline and Rosenberg views. These exclude fracture, loose bodies and osteoarthritis.
• MRI (sensitivity over 90%) is the investigation of choice.
• Signs on MRI: the double PCL sign (the displaced fragment lying beneath the posterior cruciate ligament), the absent bow tie sign (fewer than two bow tie slices on sagittal images), the flipped meniscus sign, the fragment in the notch sign, and a truncated meniscal body on the coronal image.
• MRI also shows the associated anterior cruciate ligament injury, bone bruising and chondral injury.
• Diagnostic arthroscopy confirms the tear and is the treatment.

Differential diagnosis.

• Anterior cruciate ligament tear with a pseudo locked knee.
• Loose body and osteochondral fracture.
• Patellar dislocation and plica syndrome.
• Discoid meniscus and other meniscal tear patterns (radial, flap, root).

Initial management. Rest, ice, elevation and analgesia. A locked knee is an indication for early surgery. Aspiration of a tense haemarthrosis relieves pain. Gentle manipulation under anaesthesia may unlock the knee but does not treat the tear.

Surgery (arthroscopy), ideally within 2 to 6 weeks of injury while the fragment is mobile and the tissue is healthy.

• Repair is preferred in young patients, with a peripheral red red or red white zone tear, a reducible fragment and good tissue quality.
• Reduce the fragment and repair with inside out, outside in or all-inside sutures every 4 to 5 mm on both surfaces. Add a trephination or fibrin clot.
• When the anterior cruciate ligament is torn, reconstruct it in the same sitting, which improves healing.
• Partial meniscectomy: for an irreparable, degenerate, complex or chronic displaced tear, removing only the damaged part (preserve as much rim as possible).
• Meniscal allograft transplantation is an option for young patients with symptomatic subtotal meniscectomy.

Rehabilitation after repair.

• Protected weight bearing (touch to partial) for 4 to 6 weeks, with a hinged brace limiting flexion to 90 degrees for 4 to 6 weeks, avoiding deep squatting and rotation for 4 to 6 months.
• Full range of motion by 6 to 8 weeks, then strengthening; return to running at 4 to 5 months and sport at 6 to 9 months.
• After partial meniscectomy: weight bearing as tolerated, with return to sport in 4 to 8 weeks.

Operative antibiotic prophylaxis. Cefazolin 2 g intravenously (3 g when weight is 120 kg or over) within 60 minutes before incision as a single dose (repeat after 4 hours or blood loss over 1500 mL).

With severe penicillin allergy, give vancomycin 15 mg/kg intravenously starting 90 to 120 minutes before incision as a single dose, with levels and creatinine checked in prolonged cases.

Thromboprophylaxis. Enoxaparin 40 mg subcutaneously once daily for 7 to 14 days (until the patient is fully weight bearing and mobile) in patients with a lower limb brace and restricted weight bearing or with extra risk factors after arthroscopy.

Use 20 mg once daily at creatinine clearance under 30 mL/min. Adjust by anti-Xa level in obesity and renal impairment. Check the platelet count on days 5 to 14 for heparin induced thrombocytopenia. Routine prophylaxis is not needed after simple arthroscopy in low risk patients.

Analgesia.

• Paracetamol 1 g orally every 6 hours as needed for up to 5 to 7 days (maximum 4 g daily; 3 g daily when weight is under 50 kg, with chronic alcohol use or hepatic impairment).
• Ibuprofen 400 mg orally every 8 hours with food for up to 5 days (maximum 1200 mg daily); avoid with eGFR under 30 mL/min/1.73 m2, peptic ulcer, heart failure or anticoagulant use.
• Oral morphine 5 to 10 mg every 4 hours as needed for severe pain for up to 3 days (start 2.5 to 5 mg with age over 75 or eGFR under 30 mL/min/1.73 m2; avoid exceeding 60 mg in 24 hours without senior review).
• Monitor sedation and respiration and prescribe a laxative.

Monitoring. Wound and neurovascular check at 2 weeks. Range of motion and quadriceps strength at 6 weeks, 3 months and 6 months. Locking, swelling and joint line pain at each visit. MRI at 6 to 12 months or when symptoms recur after repair. Osteoarthritis on weight bearing radiographs at 1 year and later.

Referral and escalation. Refer every locked knee to orthopaedics or sports medicine within 24 to 72 hours. Same day referral for a hot swollen joint (septic arthritis), a vascular deficit or a dislocated knee.

Special groups.

• Children and adolescents: repair is strongly preferred because meniscal loss has a high lifetime cost; discoid menisci tear easily.
• Older adults: degenerative bucket handle tears usually do not heal; partial meniscectomy is considered after physiotherapy.
• Anterior cruciate ligament deficiency: reconstruct in the same sitting to protect the repair.
• Kidney impairment: avoid ibuprofen and reduce morphine doses.