Posterior Knee Capsule Detail

capsula articularis posterior genus detail

The posterior knee capsule is the posterior fibrous sleeve of the knee joint, reinforced by the oblique popliteal ligament (semimembranosus expansion), the arcuate ligament complex, and the posterior meniscotibial ligaments. It forms the posterior boundary of the popliteal space.

Anatomical Data

Boundaries & Contents

Location	Posterior aspect of the knee joint, deep to the popliteal vessels and tibial nerve
Boundaries	Femoral attachment: posterior margins of both femoral condyles and the intercondylar line Tibial attachment: posterior margins of the medial and lateral tibial condyles Thickened by the oblique popliteal ligament medially and the arcuate popliteal ligament laterally Posterior meniscotibial fibres link it to the menisci
Contents	Posterior recesses of the knee joint cavity Synovial membrane and synovial fluid

Biomechanics

Function & Actions

Encloses the back of the knee joint, tightens as the knee straightens to limit hyperextension, and backs up the PCL against posterior tibial translation.

Clinical Relevance

Clinical Notes

Posterior capsule rupture in knee dislocation allows popliteal artery injury, the posterior capsule protects the popliteal vessels, and its disruption is a risk marker for vascular injury. Baker's cyst (popliteal cyst) communicates with the joint through a posterior capsular defect at the posteromedial margin.

Pathology

Common Injuries & Conditions

Baker's Cyst, Posterior Capsular Communication

Synovial fluid herniation through a posterior knee capsular defect producing a popliteal cyst, managed by arthroscopic treatment of the underlying joint pathology rather than direct cyst excision.

Posterior Capsule Disruption in Knee Dislocation

Posterior capsular rupture accompanying knee dislocation exposing the popliteal vessels to injury, vascular assessment (ABI or CT angiography) is mandatory after knee dislocation.

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