Tibial tubercle transfer, also called bony realignment or osteotomy, is a surgical treatment option for instability, arthritis or cartilage defects affecting the patellofemoral joint (kneecap and femur). During the operation, the orthopedic surgeon moves a small portion of bone where the patella tendon and repositions or transfers it to a location on the tibia (shinbone) in order to correct the underlying problem.
Candidates for tibial tubercle transfer include:
Symptoms of these conditions include a distinct type of stiffness and pain in the front of the knee that is experienced after prolonged periods of sitting, such as on airplane flights or at the theater, or when transitioning from a sit to stand position. Exercises involving squats and lunges, as well as stair climbing and specifically descending can also provoke these symptoms and women may find wearing high heels painful.
At the Patellofemoral Center at the Hospital for Special Surgery (HSS), patients with pain and/or instability undergo a thorough assessment that includes a physical examination and patient history. Magnetic resonance imaging (MRI) is also a part of this evaluation, as it provides critical information on the condition of the cartilage in the patellofemoral joint and helps determine whether the patient is a candidate for tibial tubercle transfer. Often, these images can be obtained on the same day as the initial visit.
Patients undergoing tibial tubercle transfer are given regional anesthesia—a spinal block that numbs the lower half of the body—and sedation. During the operation, the surgeon ensures that the transfer will allow the tendon to guide the patella effectively into the groove on the femur, where the two bones meet in the patellofemoral joint, and that pressure has been decreased from any area where cartilage damage has occurred. In order to maintain the new position of the bone, two screws are placed to secure the bone; screws may be removed at a later point if they are bothersome to the patient. The incision required to perform the operation is approximately 3 inches in length and the entire surgery lasts about an hour.
While recovering from tibial tubercle transfer, it’s essential that the bone heal before the patient bears any weight, and patients must use crutches for the first six weeks following surgery. A continuous passive motion machine (CPM) is used at home to help prevent stiffness from developing in the joint and to minimize the development of scar tissue, it moves the knee without involving the patient’s muscles. The affected leg remains in a brace except when the CPM is in use. Adhering to these guidelines is critical to the success of the surgery.
Four weeks after the operation, an experienced physical therapist at the Patellofemoral Center at HSS evaluates the patient’s progress. Provided that the healing is progressing as anticipated and the quadriceps muscle is sufficiently strong, physical therapy and weight bearing begins at six weeks. Other measures that can help speed recovery from tibial tubercle transfer include devices that provide electric stimulation to the quadricep muscle, a bone stimulator, and Game Ready®, a machine that compresses and cools the leg, thereby reducing swelling and pain. (Insurance does not presently cover the cost of these devices.)
While recovery rates vary, most patients are able to return to work or school by two weeks, resume most forms of exercise between four and five months, and can participate in sports at nine months after surgery.
Tibial tubercle transfer has a proven record of success in appropriately selected candidates and is generally safe and well-tolerated. Rare complications include potential risk of blood clot, infection and fracture or delayed bone healing. In order to minimize risk, patients are taken off birth control pills in advance of the surgery, and smoking must be avoided for a month prior to the operation and for the duration of recovery.
Summary by Nancy Novick