Hitting the dashboard with your knee can tear the PCL
An orthopedic knee surgeon and a physical therapist explain PCL injuries
When a bent knee strikes the dashboard, it can tear the posterior cruciate ligament, or PCL. This ligament helps stop the shinbone from sliding too far backward. Swelling, pain and a sense that the knee might give way can follow. [1]
A PCL tear can also happen along with a broken bone or damage to other ligaments. So the treatment plan has to account for the whole knee, beyond the name of one torn ligament. [1]
Ask about the rest of the knee
Tell your doctor where your knee hit and whether it now buckles or feels unstable. Ask what the exam showed about the PCL and your other ligaments. An X ray can show a broken bone or a small chip of bone pulled off by a ligament. An MRI can show soft tissue. Ask whether your images and your exam agree, especially if your symptoms continue. [1]
Stick to the plan for a stable knee
A PCL injury with no other damage may get better with a brace, supervised rehab and a stretch of protected walking. If other parts are hurt too, or the knee stays unstable, you and your surgeon may discuss surgery. [1]
Ask whether you must wear the brace while you sleep or walk. Find out how much weight you can put on the leg. A therapist can teach you how to move safely between sitting, standing and lying down. They can also show you exercises that build thigh strength without straining the injured ligament. [1]
When the knee isn't moving forward
Call your knee team if the knee keeps buckling, the swelling grows or you can’t reach your planned movement goals. Get urgent care for a cold or pale foot or severe pain that keeps climbing. New, marked numbness or weakness also needs urgent care. Don’t test the knee by twisting it or walking without the support you were prescribed. [1]
Questions for your knee team
- Is the PCL the only injury, or are other parts damaged?
- What exactly are my rules for the brace and putting weight on the leg?
- What finding would change the decision about surgery?
Log each time the knee gives way
Write down every time your knee gives way. Bring that list to your next knee checkup. [1]
Sources and further reading
Use this as general background from orthopedic knee surgery and physical therapy. Hitting the dashboard can hurt more than one part of the knee. Follow the brace and walking plan made for your full set of injuries.
Keep learning
Safe Driving Resource Center
Guides, self-checks and articles for drivers, parents of new drivers, and families recovering after a crash.
