Notch impingement

The tissue impingement prevents the knee from fully extending.

What is the notch of the femur?

In the knee joint, the femur bone articuates with the tibia bone at two contact points (the rounded condyles). In this illustration the knee is bent, so it is easy to see the notch. When the knee is straightened, the condyles roll forwards and the notch disappears to the back of the knee,

The notch is the gap between the two condyles and it allows plenty of space for the two large cruciate ligaments.

There are also some smaller ligaments which pass through the notch.

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Notch impingement and the Cruciate Ligaments

Notch impingement is particularly relevant to the cruciate ligaments.

A naturally narrow notch may contribute to anterior cruciate ligament rupture, and also an 'over-bulky' graft reconstruction may impinge on the edges of the notch if the gap is not wide enough to accommodate the new graft construct. This may cause some shredding of the graft material, creating a 'cyclops lesion'.

This illustration shows a cyclops lesion filling the upper part of the notch.

Impingement may prevent the knee from straightening fully, and sometimes which can lead to a 'clunk' as the person forces the knee into extension (ie straight). Eventually it may become impossible to fully extend the knee.

• Quote from peer-reviewed paper:

  "....important anatomic risk factors in ACL tears are the morphometric parameters of the intercondylar notch....[and] the relative angular position of the tibia with respect to the femur"

  Citation: Fernández-Jaén T, López-Alcorocho JM, Rodriguez-Iñigo E, Castellán F, Hernández JC, Guillén-García P. The Importance of the Intercondylar Notch in Anterior Cruciate Ligament Tears. Orthop J Sports Med. 2015 Aug 5;3(8):2325967115597882. doi: 10.1177/2325967115597882. PMID: 26535388; PMCID: PMC4622305.

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Notch impingement and Osteoarthritis

The notch can become narrow when arthritis affects the joint. Cysts and spurs (osteophytes) may develop and cause issues.

• Quote from peer-reviewed paper:

  "....The existence of osteophyte will increase the risk of the complication of anterior cruciate ligament (ACL) injury....."

  Citation: Chen C, Ma Y, Geng B, Tan X, Zhang B, Jayswal CK, Khan MS, Meng H, Ding N, Jiang J, Wu M, Wang J, Xia Y. Intercondylar Notch Stenosis of Knee Osteoarthritis and Relationship between Stenosis and Osteoarthritis Complicated with Anterior Cruciate Ligament Injury: A Study in MRI. Medicine (Baltimore). 2016 Apr;95(17):e3439. doi: 10.1097/MD.0000000000003439. PMID: 27124033; PMCID: PMC4998696.

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What can be done about notch impingement?

The classical surgical management for notch impingement is a notchplasty.

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Forum discussions

• How to avoid another cyclops

  A patient develops a cyclops lesion after ACL replacement and meniscus repair.

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