Posteromedian corner knee MRI

7/24/2019 Posteromedian corner knee MRI

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POSTEROMEDIAL

CORNER OF THEKNEE


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Introduction

Posteromedial corner - Posterior thirdof the medial aspect of the knee.

Structures between posterior borderof the supercial medial collateralligament and the medial border ofthe posterior cruciate ligament.

Has dynamic stabilizing eect.


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Components of thePosteromedial

CornerComplex

Suggested ImagingPlanes for MRI

Visualization

POL Axial

Distalsemimemranosusm!otendinous com"lex

Sa#ittal and axial

OPL Axial and sa#ittal

Meniscotiial li#ament Coronal

Posterior $orn o%medial

meniscus

Sa#ittal


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Posterioroli&ueli#ament

PO arisesfrom adductortubercle.

Has branchinginsertion with! arms.

Supercial"

tibial"capsulararms.


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POL insertion

Supercial arm blends with thesheath of the direct insertion ofsemimembranosus tendon.

#ibial arm inserts into the medialmeniscus close to the articularmargin of the posterior tibia.

$apsular arm blends with theposterior capsule and OP.


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Semimemranosis m!otendinouscom"lex

$onsists of %arms.

&nterior 'tibial

or re(ected) *irect

+nferior'popliteal)

$apsular arms OP

e,pansion


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Semimemranosis m!otendinouscom"lex

&nterior arm e,tends anteriorly" under thePO to attach to medial aspect of pro,imaltibia.

*irect arm inserts at the tibial tubercle onthe posterior aspect of the medial tibialcondyle.

+nferior arm traels more distally than the

direct and anterior arms" to attach ustaboe the tibial attachment of the /$.

$apsular arm coalesces with the capsular

portion of the obli0ue popliteal ligament.


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Semimemranosistendon''

Pulls PH// out ofthe oint during(e,ion.

&ct as a dynamicrestraint to alguswith the knee

e,tended. +n knee (e,ion the

muscle acts to

restrict e,ternal


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Oli&ue "o"litealli#ament &rises from the con(uence of the

lateral e,pansion ofsemimembranosis and the capsular

arm of PO.

$ourses superolaterally along theposterior oint capsule to the arcuate

ligament and lateral head of thegastrocnemius.


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OPL


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PHMM( Meniscotiialli#ament

*eep medialcollateral ligament-made up ofmeniscofemoral andmeniscotibial bres.

Separated from the

supercial /$ bythe /$ bursa.


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Clinical si#ni)cance

*isruption of the posteromedial corner can resultin anteromedial rotatory instability of the knee.

Strong association between P/$ and &$ inury.

+solated &$ deciency" P/$ compensates to

maintain stability. P/$ inury with a ruptured &$ - ariable

postoperatie outcome after &$ reconstruction.

+solated inury to the /$ - $onseratie

Presence of associated posteromedial cornerinury - surgery


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POL in*uries

$omprise sprains" partial tears" andcomplete tears.

+rade Imicrosco"ic

tear

Li#ament o% normal t$ic,ness and intact(-it$ edema .T/ $i#$ si#nal0 surroundin#

t$e li#ament

1rade ++partial tear

#hickening of ligament with partialdisruption of bres and increased amountof surrounding edema2hemorrhage

1rade +++complete tear

$omplete disruption of the ligament" withsurrounding edema2hemorrhage


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POL In*uries


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POL In*uries


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In*uries to distalsemimemranosis insertion

Occur in up to 345 of posteromedialcorner inuries.

&ulsion fractures- usually occur atinsertion of the direct arm.

Partial tears and strains- usuallyinole the capsular arm.

$omplete tears" tendinosis.


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In*ur! to t$e semimemranosisinsertion


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Medial meniscoca"sularlesions

Posterior third of medial meniscus hasintimate anatomic relations with the deepstructures.

6irm attachment to the tibia- by the

meniscotibial portion 'coronary ligament) ofthe deep /$.

+nuries- disruption" thickening" or bonyaulsion 'reerse Segond fracture).

/eniscocapsular separation- (uid betweenthe periphery of the meniscus and knee ointcapsule with discontinuous or irregularheterogeneous meniscal attachments.


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Medial meniscoca"sularlesions


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In*uries to OPL

Primary ligamentousrestraint to kneehypere,tension.

+nuries may manifestas irregularity of thefascia like structure"

with edema in thedeep posteromedialaspect of the knee.


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Conclusion

P/$ 7 conned in a narrow space" anatomydoes not follow classical imaging planes.

As long as the semimembranosus corner

functions eciently as a stabilizer, even aweak or damaged cruciate ligament canfunction in a compensated fashion. But ifthis stabilizing eect is lost, the anterior

cruciate ligament alone is incapable ofcompensating and becomes increasinglyinsucient.! /uller 8" 9:;!

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Posteromedian corner knee MRI