Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Palpation of the extensor mechanism

This is performed on an extended knee.First the muscular structures are ascertained. Ask the patient to extend the slightly bent knee
and resist the movement.This movement usually outlines the vastus
medialis, vastus lateralis, rectus femoris and the patellar ligament.
Then the patellar border with its tendinous insertions are palpated. With the hip in flexion and the knee in full extension, the patella can be moved freely upwards and downwards in the patellar groove. Also side gliding and tilting is
possible.

The superoposterior border of the bone and the suprapatellar tendon can be palpated after the lower pole of the patella has been pressed
posteriorly and upwards by the web of the thumb of the other hand .
The medial and lateral edges of the patella together with the quadriceps expansions are palpated in the following way. With the thumb of one hand, the patella is tilted and pushed over to the other side. Place the ring finger of the
other hand under the projecting edge and press upwards, squeezing the tendinous fibres against the posterior aspect of the patella.

The inferior pole of the patella and the insertion of the infra patellar tendon (patellar ligament) are palpated in a similar way. Place one hand just above the patella, so that the web of the thumb can exert downwards pressure. This
stabilizes the patella and tilts the apex upwards, so it can be palpated with more accuracy .

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