Patella alta

Written by Dr Sheila Strover on March 14, 2025

In patella alta the kneecap rides too high up on the femur (thigh bone). This may make it liable to sublux or even dislocate.

Illustration of a high-riding patella (patella alta) subluxing to the outer (lateral) side during knee extension. Because the underlying trochlear groove is flatter at its upper end, it is easier for the patella to slide over the edge of the groove when the knee is in extension (straight).

Illustration of front of the knee, to show the position of a high-riding patella compared to the normal position.

What is the cause of patella alta?

Patients with primary patella alta are generally born that way. It may cause no problem, or they may suffer from anterior knee pain and/or patellar instability.

In cases of rupture or avulsion of the patellar tendon, the quads muscle may pull the patella into an abnormally high position.

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How does the surgeon evaluate patellar height?

Surgeons use different indices to evaluate patellar height, such as the Insall-Salvati ratio and the Caton-Deschamps index.

The surgeon will also take other parameters into consideration before discussing surgery with the patient.

There are "....many variations in patella alta definitions and descriptions, measurement methods, cutoff values, and treatment options...."

Roland M Biedert et al

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How serious is patella alta?

Patella alta may simply be a finding on X-ray or examination. But if the patient complains that the patella is unstable, tending to sublux or even dislocate, that the surgeon would be prompted to investigate further and consider surgical intervention.

"Patella alta is a major contributor to recurrent patellar instability....in young athletes...."

Paige Hinkley et al

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Can a knee brace fix patella alta?

A 'do-nut' brace, with a cutout to accommodate the patella, may be helpful in reducing incidence of subluxation or dislocation, but it not likely to change the anatomy itself.

Physiotherapy taping may also be helpful, together with exercise of the VMO part of the quadriceps muscle.

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Surgery for patellar instability

Surgery may be undertaken in patients where instability is very problematic. Surgery may be proximal (above the kneecap), distal, or a combination, and include:

"Distalizing tibial tubercle osteotomy has been used for the correction of patella alta and patellar instability, but this procedure is contraindicated in the skeletally immature patient population, as it could lead to growth arrest of the proximal tibial physes."

Paige Hinkley et al

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A-Z Keywords

Anterior knee pain, Patellar instability, Patellar tendon rupture, Insall-Salvati ratio, Caton-Deschamps Index, Patellar instability, Patellofemoral dislocation,Patellar instability, J sign, Patellar brace, Patellar dislocation, Patellar subluxation, Trochlear dysplasia, TT-TG Distance

Contributions by Experts -

Dr Ronald Grelsamer - Patellofemoral pain

Forum discussions

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