Working Diagnosis:
Grade 2 LCL Sprain with Avulsion Fracture of Fibular Head and Posterolateral Corner Injury
Outcome:
Office visits completed at 2,3,4,6,and 9 weeks
Therapy: Patient completed 17 total sessions of PT and daily treatment with ATC with emphasis on range of motion and strengthening of quadriceps and hamstrings
Hinged knee brace ordered at 9 weeks following injury and patient cleared for participation in sport at that time
Editor's Comments:
Isolated lateral collateral ligament (LCL) injuries are rare. LCL injuries account for approximately 8% of all knee injuries. The LCL is the second least injured knee ligament, with the PCL being the least injured. LCL injuries often result from varus stress with hyperextension to the knee. Other knee structures are commonly injured with the LCL including underlying injuries to the posterolateral corner, lateral meniscus, and sometimes the cruciate ligaments (both the ACL and PCL). Studies show that up to 49% of LCL injuries are treated with surgery. This is the result of LCL injuries often being part of multiligamentous knee injuries.
On imaging, a small avulsion fracture of the proximal fibular head <1cm, known as the arcuate sign, is pathognomonic for a posterolateral corner injury (PLC). If present, an LCL injury should also be considered. MRI should be considered in these situations to assess for other associated soft tissue injuries that cannot be seen on plain xray. Varus stress xrays can be useful if MRI or ultrasound is not readily available. Musculoskeletal ultrasound is useful for both static and dynamic exam of the LCL to assess ligament integrity.
Consultation with an orthopedic surgeon should be considered with acute LCL tear with signs of function instability and when associated posterolateral corner injury is present, as these injuries often require surgery. Isolated Grade 1 and Grade 2 LCL injuries without functional instability can be treated conservatively with bracing, modified weightbearing, and physical therapy.
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