Posterolateral Corner Injuries: Causes, Symptoms, and Treatment

Individuals who have sustained trauma to the knee area from work, physical activity, or a motor vehicle collision can experience significant pain and mobility impairment. Can physical therapy help heal and strengthen the PLC?

Posterolateral Corner Knee Injury

The posterolateral corner, or PLC, comprises muscles, tendons, and ligaments in the back of the knee that help support and stabilize the outside region. The primary role of the PLC is to prevent the knee from excessive amounts of rotation or bowing/turning outward. (Chahla J. et al., 2016) Posterolateral corner injuries can cause significant pain and can dramatically impact an individual’s ability to walk, work, or maintain independence. Treatment options will depend on the severity of the injury.

The Posterolateral Corner

The posterolateral corner comprises multiple structures that support and stabilize the outside of the knee. The structures are subdivided into primary and secondary stabilizers. The primary group includes:

• Lateral collateral ligament- LCL
• Popliteofibular ligament – PFL
• Popliteus tendon

The secondary stabilizers include:

• The lateral capsule of the knee.
• Coronary ligament.
• Fabellofibular ligament.
• Lateral gastrocneumius tendon.
• The long head of the biceps femoris.
• Iliotibial/IT band (Chahla J. et al., 2016)

The primary role is to prevent the knee from excessively turning outward, so the grouping provides secondary assistance in preventing the lower leg bone/tibia from shifting forward or backward on the thighbone/femur. Occasionally, one or several posterolateral corner structures can be sprained, strained, or torn.

How Injury Occurs

An injury occurs when a direct blow to the inner portion of the front of the knee causes the leg to bow outward. A posterolateral corner injury may also be sustained without contact, for example, if the knee hyperextends or buckles away from the other leg into a varus/bow leg position. Because the knee usually moves during a PLC, concurrent sprains or tears to the anterior cruciate ligament/ACL or posterior cruciate ligament/PCL are also common. (Chahla J. et al., 2016) Other situations that can also cause PLC injuries include automobile crashes and falls from elevated surfaces. (Shon O. J. et al., 2017) When this type of trauma causes a posterolateral corner injury, bone fractures are also common.

Symptoms

Depending on the severity of the injury, multiple symptoms may be present, including:

• Difficulty walking or climbing stairs due to instability. (Shon O. J. et al., 2017)
• Numbness or tingling in the lower leg.
• Pain, swelling, bruising, and hardening in the knee and surrounding area.
• Outward bowing position of the affected knee when standing.
• Foot drop presents on the injured side. (Chahla J. et al., 2016)

For individuals who suspect that they have sustained a PLC injury or have any of the symptoms listed, it is critical to be seen by an orthopedic specialist or emergency room physician. A healthcare provider will properly evaluate the leg and develop the appropriate treatment.

Diagnosis

Diagnosis begins with a comprehensive examination. In addition to looking for the symptoms noted, a healthcare provider will move the legs in different directions to assess for any instability. The dial test may be performed, which involves having the patient lie on their stomach while the healthcare professional assesses the side-to-side rotation in the leg to check for excessive motion. (Shon O. J. et al., 2017) Imaging is frequently ordered to determine which anatomical structures are affected more accurately. X-rays can help rule out concurrent fractures and check for excessive laxity in the knee area. MRIs are also useful for visualizing the various tendons and ligaments, helping the healthcare provider look closely at any sprains or tears that may have occurred. However, MRIs may be less accurate in diagnosing PLC injuries after 12 weeks, so they should be obtained as soon as possible. Based on this evaluation, the injury may be classified using the following system (Shon O. J. et al., 2017)

Grade 1

• 0 to 5 degrees of rotational or varus/bowing instability.
• Incompletely torn posterolateral corner.

Grade 2

• 6 to 10 degrees of rotational or varus/bowing instability.
• Incompletely torn posterolateral corner.

Grade 3

• Eleven or more degrees of rotational or varus/bowing instability.
• Completely torn posterolateral corner.

Treatment

The care received after a posterolateral corner injury can vary depending on the structures involved and the overall severity.

Nonsurgical

Nonsurgical treatment is typically reserved for isolated grade 1 or 2 PLC injuries. (Shon O. J. et al., 2017) Depending on which structures are affected, a stabilizing brace may be worn, and crutches are often needed to decrease the strain on the knee. Physical therapy is also commonly prescribed and focuses on the following goals:

• Gradually reducing crutch use.
• Improving balance and stability.
• Improving walking patterns.
• Regaining the range of motion in the knee.
• Strengthening the leg muscles.
• Gradually reintroducing specific movements like running and jumping.

Surgery

Non-surgical treatment tends not to work with grade 3 injuries. If surgery is not performed, individuals may also suffer from chronic knee instability or develop long-term osteoarthritis. (Chahla J. et al., 2019) Surgical treatment is often recommended for grade 3 injuries. The damaged primary stabilizers are surgically reconstructed using a graft from another body region. Surgical repairs may also be performed on any secondary stabilizers to improve stability. (Chahla J. et al., 2019) Any other ligament injuries, such as ACL, PCL, or concurrent fractures, will also be addressed. Following the procedure, individuals immobilize their knee with a brace and do not place weight on the affected leg to protect the surgical area. Depending on the surgeon’s recommendations, this can last six weeks or more. Physical therapy is also initiated after a surgical procedure. Though rehabilitation progresses slowly, the goals are often the same as when treating milder PLC injuries. Returning to work, sports, and/or physical activity after surgery may take six months of therapy or more. (Shon O. J. et al., 2017)

Injury Medical Chiropractic and Functional Medicine Clinic works with primary healthcare providers and specialists to develop a personalized treatment program through an integrated approach to treat injuries and chronic pain syndromes, improve flexibility, mobility, and agility, relieve pain, and help individuals return to normal activities. If other treatments are needed, Dr. Jimenez has teamed up with top surgeons, clinical specialists, medical researchers, and rehabilitation providers to provide the most effective treatments.

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Knee Injury Rehabilitation

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References

Chahla, J., Moatshe, G., Dean, C. S., & LaPrade, R. F. (2016). Posterolateral Corner of the Knee: Current Concepts. The archives of bone and joint surgery, 4(2), 97–103.

Shon, O. J., Park, J. W., & Kim, B. J. (2017). Current Concepts of Posterolateral Corner Injuries of the Knee. Knee surgery & related research, 29(4), 256–268. doi.org/10.5792/ksrr.16.029

Chahla, J., Murray, I. R., Robinson, J., Lagae, K., Margheritini, F., Fritsch, B., Leyes, M., Barenius, B., Pujol, N., Engebretsen, L., Lind, M., Cohen, M., Maestu, R., Getgood, A., Ferrer, G., Villascusa, S., Uchida, S., Levy, B. A., Von Bormann, R., Brown, C., … Gelber, P. E. (2019). Posterolateral corner of the knee: an expert consensus statement on diagnosis, classification, treatment, and rehabilitation. Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 27(8), 2520–2529. doi.org/10.1007/s00167-018-5260-4