Posterolateral corner injuries of the knee

Ross Hauser, MD

The knee is a complex joint of many parts. The posterolateral corner (PLC) of the knee is one such complex area. However a complex area can be described simply: (postero) back (lateral) outside – the back and outer side of the knee. It can also be treated in many cases more simply than with aggressive reconstructive surgery.

Numerous research studies cite that the three major anatomical structures that have been described as the primary stabilizers of the PLC of the knee are:

lateral collateral ligament,
popliteus tendon, and
popliteofibular ligament.

Research lead by the Steadman Philippon Research Institute suggest:

These injuries most commonly occur concurrent with cruciate ligament tears. These static stabilizers (the lateral collateral ligament, popliteus tendon, and popliteofibular ligament function to prevent increased varus (bowleggedness) and excessive rotation or hypermobility of the knee.

Let’s note that stabilizers prevent knee instability. When stabilizer are unstable, injured, worn, knee instability ensues.

Bones:

the shin bone, (tibia)
the fibula or “calf bone”
the lower outside of the thigh bone or lateral femur

Connective tissue:

lateral collateral ligament (LCL), connecting thigh and calf bone.
iliotibial band (IT band),
biceps femoris muscle of the hamstring – tendon heads or attachments
the popliteus tendon, (which supports small muscles in the back of the knee).
the popliteofibular ligament
the lateral gastrocnemius tendon (affecting the calf muscle)
and the fabellofibular ligament.1

In new research for the University of Utah and University of Michigan, doctors suggest that because anterior cruciate ligament (ACL) and posterior cruciate ligament injuries rarely occur in isolation and are often associated with injuries to the secondary or supporting structures that provide stability against rotational forces. Doctors should examine the posterolateral and posteromedial corner ligaments and tendons, as well as the anterolateral ligament.

If injuries to these secondary structures are not appreciated at the time of cruciate ligament reconstruction, an isolated cruciate ligament reconstruction may be predisposed to early failure.2

1 Kennedy NI, LaPrade CM, LaPrade RF. Surgical Management and Treatment of the Anterior Cruciate Ligament/Posterolateral Corner Injured Knee. Clin Sports Med. 2017 Jan;36(1):105-117. [Pubmed]

2 Hansford BG, Yablon CM. Multiligamentous Injury of the Knee: MRI Diagnosis and Injury Patterns. Semin Musculoskelet Radiol. 2017 Apr;21(2):63-74. doi: 10.1055/s-0037-1599208. Epub 2017 Mar 29. [Pubmed]