Glossary
Trochlear dysplasia
Quick answer
Trochlear dysplasia means the groove at the end of the thigh bone, where the kneecap glides, is shallow, flat or even bumped instead of a deep V. With less bony guidance the kneecap can slip out more easily, explains Doha knee surgeon Dr. Pablo Gelber, who treats kneecap instability at Aman Hospital.
What it means
The trochlea is the V-shaped groove on the front of the femur. Dysplasia means abnormal development. The groove forms before birth and in childhood, so trochlear dysplasia is something you grow up with rather than an injury.
Radiologists may grade it, often A to D in the Dejour system, from a slightly shallow groove to a flat or convex one with a prominent bump at the top. Signs such as the crossing sign or a supratrochlear spur may be mentioned.
Why it matters
Trochlear dysplasia is the most common anatomical factor in people whose kneecap dislocates more than once. It often sits alongside patella alta and a torn medial patellofemoral ligament.
Mild forms may cause no trouble. Severe forms, especially with a large bump, can cause pain at the front of the knee and make simple soft-tissue surgery less reliable.
How it is treated
Physiotherapy to improve hip and quadriceps control is the starting point. For recurrent dislocations, MPFL reconstruction is the core operation and works for most degrees of dysplasia. In severe high-grade cases with repeated failure, a trochleoplasty, which deepens the groove, may be considered by surgeons experienced in the technique.
Frequently asked questions
Was I born with trochlear dysplasia?
Usually yes. The shape of the groove develops in childhood. It may only become noticeable when the kneecap first dislocates, often in the teenage years.
Does every person with trochlear dysplasia need surgery?
No. Many never dislocate. Surgery is considered for repeated dislocations or persistent instability despite rehabilitation.
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