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.

Region: Knee

Biomechanics

Function & Actions

Provides the posterior knee joint containment, resists posterior tibial translation supplementing the PCL, limits knee hyperextension, and defines the posterior boundary between the joint and the popliteal neurovascular structures.

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.