The knee becomes 'locked' when the 'bucket-handle' suddenly flips over, trapping the condyle from moving freely.
How do 'bucket-handle' tears occur?
A twisting incident may cause the initial longitudinal tear of the meniscus.
If the tear is long, or if the initial tear is ignored and slowly lengthens, any awkward movement may cause the separated part of the meniscus to flip over and get stuck under the rounded condyle of the femur, locking the joint.
Sometimes such a bucket-handle tear can spontaneously reduce, with motion suddenly restored.
Natural history of the 'bucket-handle'
With each episode the meniscus tear may extend and the 'handle' bit may flip over more easily.
Eventually the 'handle' may break and its free end may flap in the joint, causing periodic catching or locking. Eventually the torn bit may break off altogether, to float in the joint as a 'loose body', also causing intermittent catching or locking.
How are bucket-handle tears managed?
A patient may find that the displaced portion flips back on its own, with immediate relief of locking - but the locking may recur, and each episode may cause the tear to extend.
A locking episode can often be temporarily resolved with a manual manipulation, but this only relieves the immediate symptoms and does not fix the underlying problem.
In most cases of bucket-handle tear, today's surgeon will generally attempt a repair procedure, but in some cases the surgeon may decide that the damage is too great and it is best to cut away the 'handle' (partial meniscectomy) rather than attempt a repair. A tricky consideration is that immediate rehabilitation is easier for the partial meniscectomy.
"As the menisci are critical for load transmission, stabilization, lubrication, and proprioception of the knee joint, preservation of meniscal tissue is of great clinical importance...."
"....few complications occur after arthroscopic repair of bucket-handle meniscus tears, and the results are relatively durable....given the young, athletic population that is affected by this injury pattern—surgeons should attempt meniscal repair at the index surgery...."
"Although repair is attempted whenever possible, meniscus resection [is] usually performed for a tear that cannot be repaired or less likely to heal afterwards, for example: bucket handle tear in the avascular zone.... "
"....removal of meniscal tissue results in cartilage degeneration, premature development of osteoarthritis, and poor long-term outcomes"
Other relevant links -
Locking, Longitudinal tear, Torn meniscus, Meniscal repair augmentation, Loose body, Catching, Locked knee, Meniscal repair, Partial meniscectomy
Forum discussions
- My Meniscus & Its Repair-- Was It Supposed to Be This Bad? - A post-op diary of the early days of meniscal repair after a bucket-handle tear.
- Lateral Meniscus Tear - To Scope or Not to Scope??!? - A personal story that illustrates how a bucket-handle tear can 'self-reduce'.