Eric Young, MD
Phone: 970-766-3222 Fax: 970-776-3226
COLORADO ORTHOPEDIC 3830 N. Grant Avenue | Loveland, CO 80538
& HAND SURGERY
Knee Ligaments by Dr. Eric younG
There are four principle ligaments in the knee; the anterior cruciate ligament(ACL), posterior cruciate ligament(PCL), medial
collateral ligament(MCL), and the lateral collateral ligament(LCL). Any of these ligaments may be injured, and combined
injuries are common. Injuries to the collateral ligaments present as pain along the inner(medial) or outer(lateral) side of the
knee. Pain can be mild to severe. The ligament can be partially or completely torn. Treatment of isolated collateral ligament
tears rarely requires surgery. Bracing, use of crutches, and physical therapy are treatment options. It may take several months
to regain normal, pain-free knee function after this type of injury.
Injuries of the anterior cruciate ligament (ACL) can range from a sprain to a complete tear. These injuries are often the result
of a twisting or hyperextension motion in sports. Frequently there is a “pop” heard or felt at the time of injury. There is often
significant swelling of the knee shortly after the injury. Sometimes it is possible to walk relatively well following the injury,
but pivoting on the injured leg may be difficult.
This ligament prevents forward sliding of the tibia in relationship to the end of the femur. It also plays a role in controlling
rotation of the knee. When the ligament is completely torn the knee moves in an abnormal fashion and may be unstable.
Diagnosis can often be made by physical examination, but in cases where there is doubt; MRI of the knee is very helpful.
Associated injuries to the meniscal cartilages, collateral ligaments, and joint surfaces are common. MRI can be very helpful
in identifying these associated injuries.
Nonsurgical treatment of ACL tears includes rehabilitation of the knee to recover movement and strength. Bracing may
be needed for everyday activities or for sports. Surgical reconstruction of the ligament is usually recommended in active
individuals, athletes, and those who have physically demanding jobs. Some pre-existing conditions, such as severe arthritis,
may preclude the possibility of successful surgery.
ACL reconstruction is performed arthroscopically. At the time of the surgery other problems in the joint such as meniscus
tears can be addressed. It is necessary to replace the torn ligament with a new piece of tissue as the injured ligament is not
repairable. Sources for this replacement tissue include a portion of the patellar tendon, part of the hamstrings tendons, or
tendon from a cadaver donor. Currently there are no artificial replacement ligaments available. The surgery is performed
using general or spinal anesthesia and usually takes less than 2 hours.
Following surgery a brace is applied to the knee. Initially the brace is locked in an extended position. As strength and
movement in the leg improve the hinges of the brace are unlocked to allow increasing movement. Use of a continuous
passive motion machine(CPM) may be helpful in regaining movement in the knee. Physical therapy can be very helpful in
restoring function to the knee. Rehabilitation usually takes about 6 months following surgery, and it often is 1 year or longer
before one can return to unrestricted sports activities. Protective bracing for sports may also be recommended after surgery.
Posterior cruciate ligament tears are much less frequent than ACL tears. PCL tears can occur from a fall onto the flexed knee,
an automobile accident, or some types of sports activities. Diagnosis of PCL tears can be made by physical examination, but
sometimes an MRI is required to identify or confirm the diagnosis. In most cases an isolated PCL tear can be treated with
rehabilitation and bracing. Surgical reconstruction is not usually necessary, but may be required for some athletes and in
cases where the instability is not well controlled with rehabilitation and bracing.