Lateral collateral ligament injury and related posterolateral corner injuries of the knee
- Sean N Martin, DO
Sean N Martin, DO
- Eglin Air Force base Family Medicine Residency
- Kevin deWeber, MD, FAAFP, FACSM
Kevin deWeber, MD, FAAFP, FACSM
- Family Medicine of SW Washington Residency
- PeaceHealth SW Medical Center
- Affiliate Associate Professor of Family Medicine
- Oregon Health and Science University
- Clinical Instructor of Family Medicine
- University of Washington School of Medicine
- Section Editor
- Karl B Fields, MD
Karl B Fields, MD
- Editor-in-Chief — Primary Care Sports Medicine (Adolescents and Adults)
- Section Editor — Biomechanics, Rehabilitation, and Recovery; Sports-Related Injuries; Symptom Assessment and Physical Examination
- Professor of Family Medicine and Sports Medicine
- University of North Carolina at Chapel Hill
Isolated injuries of the lateral collateral ligament (LCL) are among the least common knee injuries but can occur when the joint is struck from the inside (varus stress). More commonly, the LCL is injured along with other structures, often including those of the posterolateral corner of the knee but also possibly the anterior or posterior cruciate ligaments, during more significant trauma. The care of uncomplicated, minor LCL injuries can be supervised by primary care clinicians, but more severe injuries warrant orthopedic referral.
The presentation, evaluation, diagnosis, and nonoperative management of LCL injuries are reviewed here. Other knee injuries and an overall approach to knee complaints in active adults are discussed separately. (See "Approach to the athlete or active adult with knee pain" and "Anterior cruciate ligament injury" and "Meniscal injury of the knee" and "Medial collateral ligament injury of the knee" and "Patellofemoral pain".)
The lateral collateral ligament (LCL) works in concert with the other soft tissue structures of the arcuate ligament complex to provide posterolateral stability to the knee . The primary posterolateral stabilizing structures are commonly considered to be the LCL, popliteus tendon, and the popliteofibular ligament (PFL). Other stabilizing structures include the biceps femoris and lateral gastrocnemius muscles and tendons; and the popliteal meniscal, fabellofibular, oblique popliteal, and arcuate ligaments .
In addition, as an independent structure, the LCL acts as a barrier to varus instability at all angles of knee flexion . The LCL may also act with the other primary posterolateral structures to prevent posterior translation  and external rotation of the tibia on the femur during early knee flexion (0 to 30 degrees) [5,6]. As knee angles increase beyond 60 degrees, the LCL provides less restraint against external rotation compared to the PFL , and beyond 70 degrees, it does not provide significant resistance to external rotation .
Injury to the lateral collateral ligament (LCL) represents approximately 8 percent of all knee injuries, making it the second least commonly injured knee ligament, the posterior cruciate ligament being the least injured . Of the knee injuries treated in this study, the LCL was involved in 2.5 percent of cases. In one large retrospective study, approximately 48.9 percent of cases involving LCL injuries were treated with surgery, but half of these cases involved multiple injuries . Data pertaining to the epidemiology of posterolateral corner knee injuries are extremely limited, but such injuries are often associated with injuries to other knee ligaments [10,11].
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- RISK FACTORS
- CLINICAL ANATOMY
- MECHANISM OF INJURY
- CLINICAL PRESENTATION AND EXAMINATION
- Common presentations
- Examination findings
- Associated injuries
- Classification of LCL injury
- Approach to imaging
- Varus stress radiographs
- Magnetic resonance imaging
- Musculoskeletal ultrasound
- INDICATIONS FOR ORTHOPEDIC CONSULT OR REFERRAL
- DIFFERENTIAL DIAGNOSIS
- Acute injuries
- - Lateral meniscus tear
- - ACL tear
- - PCL tear
- - Popliteus injury
- - Physeal injury
- - Bone contusion
- - Proximal tibiofibular syndesmosis injury
- Chronic injuries
- INITIAL TREATMENT
- FOLLOW-UP AND DEFINITIVE CARE
- Unrecognized posterolateral corner injury
- Functional instability
- Peroneal nerve injury
- RETURN TO SPORT OR WORK
- SUMMARY AND RECOMMENDATIONS