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The kneecap visibly shifting — to the side, then often snapping back. A sudden “giving way” — with the knee buckling under load. Pain and rapid swelling — after a dislocation episode. Apprehension — and a fear that the kneecap will slip again.

A shallow trochlear groove (trochlear dysplasia). A kneecap that sits high or too far to the outer side. Generally loose ligaments and muscle imbalance. A previous dislocation, which raises recurrence risk.

Examination assesses how freely the kneecap can be pushed sideways and reproduces the patient’s apprehension. X-rays and an MRI then reveal the underlying anatomy — the depth of the groove, the position of the kneecap, and damage to the stabilising ligament (the MPFL) — which together guide whether surgery is needed.

Rehabilitation: A first dislocation without major damage is usually treated with strengthening and bracing to restore control of the kneecap. MPFL reconstruction: For recurrent instability, the key stabilising ligament is rebuilt with a graft to hold the kneecap in its groove. Bony realignment: Where anatomy is the driver, the attachment of the kneecap tendon or the groove itself may be reshaped.

After rehabilitation or surgery, a staged programme restores motion, then strength, then confidence in the knee. Most patients return to sport within three to six months. Modern stabilising surgery is highly effective at preventing further dislocations when the underlying cause is correctly addressed.