The knee has 4 primary stabilizing ligaments. The medial collateral ligament (on the inside) provides side to side stability. The lateral collateral ligament (on the outside) provides side to side stability. The anterior cruciate ligament in the center of the knee provides stability by not allowing the tibia to slide forward on the femur. The posterior cruciate ligament provides stability by not allowing the tibia to slide backwards on the femur.
As a team physician for professional teams as well as high school teams we commonly see significant ligament injuries to the knee. One of the less common injuries which can occur is a tear of the posterior cruciate ligament, and a pulled to do intact, and other knee ligament injuries. Patients with posterior cruciate ligament injuries experience knee pain and swelling immediately after an injury. There is likely to be instability in the knee joint and the knee stiffens with walking. This injury is often the result of a backwards force on the front of the tibia. The posterior cruciate ligament cannot be directly repaired, but can be treated operatively with a reconstruction or non-operatively with bracing and rehab.
Arthroscopic surgery helps to provide for a more anatomic type of reconstruction for this ligament. The reconstruction choices for donor grafts are either a cadaver graft or a persons own hamstring tendons or bone tendon patella tendon.
The procedure begins with an exam under anesthesia followed by a diagnostic arthroscopy. During the diagnostic portion of the arthroscopy, injuries to the meniscus and or articular cartilage can be handled with either repair or resection of the meniscus with possible transfer or articular cartilage from a non-weight bearing area to a damaged weight bearing area.
If the posterior cruciate ligament is torn, depending on the age of the patient and the activity level to be achieved, choices of the ligament donor grafts would either include autografts from the patient or allografts from a cadaver.
Position of the tunnels can be enhanced with instrumentation such as the flip cutter which will allow a pin to be drilled from the outside of the knee to the inside to a set point, and then it will become a reaming instrument by flipping a blade to form a drill for tunnel creation.
Enhanced interference fixation of the graft can be established with screws made of bioabsorbable material including bone substitute. The screws actually become bone over a period of time once put in place.
Injuries to the knee ligaments should be evaluated as soon as possible. A history and physical exam with x-rays are the beginning of the workup which may also include MRI study for further evaluation of the damage. A successful ACL reconstruction will allow your need to function more normally. It will also reduce your risk for further injury.