Background on Tibial Tubercle Transfer
The tibial tubercle is the bony prominence on the anterior medial aspect of the tibia (shin bone). It acts as an attachment for the patellar tendon and serves as a fulcrum for knee extension. In the context of patellar instability or patellar dislocation, the tibial tubercle is often positioned too far lateral (toward the outside of the knee). This can cause the knee cap to dislocate outside the lateral edge of the trochlea.
- Background on Tibial Tubercle Transfer
- History of Tibial Tubercle Osteotomy
- Video of Arthrex Tubercle Osteotomy
- Preoperative Planning
- How is Tibial Tubercle Osteotomy Performed
- Recovery after Tibial Tubercle Transfer
- FAQ. Frequently Asked Questions
Tibial tubercle transfer (TTT), also known as tibial tubercle osteotomy (TTO), or Fulkerson osteotomy, is a surgical procedure that is performed to correct lateral displacement of the tibial tubercle. The goal of the surgery is to improve patellar tracking and stability, alleviate pain, and take pressure off of the cartilage.
TTT was first described in the early 1900s as a treatment for patellar instability. It has since become a commonly-performed orthopedic procedure, with several different techniques being developed over the years. The most common indications for TTT nowadays are recurrent patellar dislocation or subluxation, chronic patellofemoral pain, and patellar instability secondary to a lateralized tibial tubercle.
The surgical technique involves transfer of the tibial tubercle from its original location to a new site on the tibia, depending on the specific pathology that is being treated. The new attachment site for the patellar tendon is usually placed just medial, and somewhat anterior, to the original location.
History of Tibial Tubercle Osteotomy
The first description of a tibial tubercle osteotomy was by Fulkerson in 1909, who used the procedure to treat patellar instability. Since then, many different surgeons have developed additional variations of techniques for performing the surgery. The basic principles remain the same, however, and involve transfer of the tibial tubercle to a new location on the tibia.
Video of Arthrex Tubercle Osteotomy
Indications for Tibial Tubercle Transfer
Patellofemoral instability is a very complex condition and occurs when the patella slides off the lateral aspect of the femur. Orthopaedic surgeons assess the entire picture and don’t make surgical decisions on just one parameter. The most common indications for tibial tubercle transfer are recurrent patellar dislocation or subluxation, chronic patellofemoral pain, and patellar instability secondary to a lateralized tibial tubercle.
Lateralization of the tibial tubercle is most often measured using the tibial tubercle-trochlear groove distance (TTTG). Normal TTTG values range from 10-12mm, while anything higher than 20mm is considered for TTT.
Other less common indications include:
* Patella alta – when the patella is positioned too high on the femur – on patients with recurrent patellar instability
* Patellofemoral cartilage loss with or without cartilage restoration procedure
* Trochlear dysplasia – when the groove that the kneecap glides in is too shallow
When considering surgery, your orthopedic surgeon will obtain a detailed history of your symptoms and previous treatments. He or she will also perform a physical examination, paying close attention to the alignment of your knee joint and the position of your patella.
Imaging studies, such as x-rays, lower extremity alignment films, CT scan, and MRI, may also be ordered to further evaluate the patellar instability or patellofemoral pain.
How is Tibial Tubercle Osteotomy Performed
There are several different types of TTT, which vary based on the specific location of the tibial tubercle transfer. Medialization TTT is the most common type of procedure and involves transfer of the tibial tubercle to a more medial position on the tibia. This is done in order to increase patellar contact with the femoral trochlea, and decrease lateral patellar tracking. Lateral release and medial patellofemoral ligament (MPFL) reconstruction is often performed in conjunction with medialization TTT, in order to further improve patellar tracking.
Tibial Tubercle Anteromedialization
Tibial tubercle anteromedialization (AMZ) is another type of TTT, which involves transfer of the tibial tubercle to a more anterior and medial position on the tibia. This procedure is typically performed in patients with lateral patellar instability who have evidence of chondral wear on the patella or trochlea. Adding anteriorization to a standard medialization procedure allows unloading of the cartilage and can help improve knee pain and less cartilage contact pressures. This helps take stress off of the patellofemoral joint.
Tibial Tubercle Distalization
Distalization is a less common type of TTT, which involves transfer of the tibial tubercle to a more distal position on the tibia. This procedure is typically performed in patients with patellar instability secondary to a high-riding patella, also known as patella alta. Patellar height is measured by using the Caton-Descamps Index or the Insall-Salvati ratio. Values higher than 1.2 indicate increased patellar height that may contribute to patellar instability and patella dislocation.
The specific surgical technique that is used will depend on the underlying causes of patellar maltracking and dislocation, as well as the surgeon’s preference. However, there are some common steps that are involved in all types of TTT.
Tibial Tubercle Transfer Technique
First, the patient is placed under general anesthesia and an incision is made over the front of the knee. The insertion of the patellar tendon onto the tibia is exposed. Next, guide pins are used to mark out the planned bone cuts (osteotomy).
A saw is then used to make an osteotomy (bone cut) along the guide pins. The tibial tubercle is then detached from its current attachment site and moved to the new position. It is important to ensure that the patellar tendon remains attached to the tibial tubercle during this process. Once the tibial tubercle is in its new position, it is typically secured with screws and/or a plate and screws. Most often 2-3 screws are placed from the anterior aspect of the tibial tuberosity into the posterior tibial cortex. These screws help to compress the bone osteotomy site.
Other soft tissue procedures may be performed at the same time as a TTT. These procedures include knee arthroscopy, lateral release, MPFL reconstruction, and cartilage restoration procedures such as MACI.
The incision is then closed with sutures and the patient is placed in a knee immobilizer. The procedure is sometimes performed as an outpatient procedure, but patients are sometimes kept in the hospital overnight for observation. Physical therapy will be started soon after surgery, and the knee immobilizer is typically worn for 4-6 weeks. Most patients are able to return to full activity within 3-4 months.
Recovery after Tibial Tubercle Transfer
The bones must heal before they can bear weight after tibial tubercle transfer. Physical therapy that focuses on knee movement is critical to avoiding stiffness and reducing scar tissue, as well as moving the knee without early after surgery. You might use a continuous passive motion machine at home for several hours each day, or your physiotherapist may help perform this movement for you. The stationary bike is started soon after surgery to help achieve knee range of motion.
Patients undergoing TTT will be sent home with crutches after surgery. Most people can put weight on their operated leg 4 to 6 weeks after surgery but won’t have full range of motion for 3 to 4 months. It can take up to a year for the MPFL graft to fully attach to the bone.
You might be able to return to your previous level of activity within 3 to 6 months, depending on what that activity is and what other surgical procedures were performed. Running and other high-impact activities will take longer, sometimes up to a year. Full recovery from any type of surgery takes time and includes regaining strength and flexibility as well as addressing any residual pain.
Return to Sports after TTT
Research studies have shown that approximately 83% of patients are able to return to sports, and somewhere between 60-77.5% of patients are able to return to the same level of sports activity after surgery.
FAQ. Frequently Asked Questions
What is a tibial tubercle transfer?
A tibial tubercle transfer is a surgical procedure used to treat malalignment of the patella, or dislocated patella. The patella, or kneecap, is a small bone at the front of the knee that helps in the movement and function of the joint. Patellar instability occurs when the patella is not properly aligned with the femur, or thighbone. This can result in pain, instability, and dislocation of the patella.
A tibial tubercle transfer is a procedure in which the tibial tubercle, a small bony prominence below the kneecap, is moved to a new position. This helps to realign the patella and improve joint function. The procedure is typically performed through an incision on the front of the knee.
How long does it take to recover from tibial tubercle osteotomy?
Most patients report excellent pain relief and functional improvement after tibial tubercle transfer. Recovery times vary from individual to individual, but most patients are kept non-weight bearing for 6 weeks. It may be 4-6 months before the bone heals enough to withstand the substantial stress that accompanies high impact activities, heavy lifting, and running.
Some may experience minor discomfort and swelling for a prolonged period of several months. It is important to follow your surgeon’s instructions during the recovery period to ensure proper healing.
What are the risks and complications associated with Tibial Tubercle Transfer?
As with any surgical procedure, there are some risks and complications associated with TTT. Research studies have shown the rate of complications to be less than 15%.
These include, but are not limited to:
Loosening or breakage of implants
Failure of the bone to heal properly
While very rare, infection can occur at the surgical site. This is more common in patients who are smokers or have diabetes.
Bleeding is also a potential complication.
Nerve injury is another potential complication, and can occur if the nerve is stretched or damaged during the surgical procedure. This typically resolves on its own within a few weeks, but may require physical therapy or other interventions.
Blood clots are a more serious complication. Blood clots can be very dangerous, and can even be life-threatening if they travel to the lungs. Patients who are at risk for blood clots (such as those who smoke or have diabetes) may be placed on blood thinners.
How painful is a tibial tubercle osteotomy?
Tibial tubercle osteotomy (TTTO) is an open procedure used to treat patellofemoral instability. This type of surgery is typically performed as an outpatient procedure, which means that the patient can go home the same day or the next day.
The TTTO procedure involves making small incisions in the knee joint and using special instruments to detach the tibial tubercle from its current attachment site. The tibial tubercle is then moved to a new position and secured with screws or a plate and screws.
Most patients report moderate to severe pain after TTTO surgery. This usually starts improving after the first week. However, every patient experiences pain differently, and some may experience more discomfort than others. Pain medication can be used to help manage any pain that does occur. Physical therapy and other holistic methods may be used to help with the pain.
From along term standpoint, knee pain typically improves dramatically. One study demonstrated an improvement in Kujala pain scores from 51.2 to 82.6 postoperatively.
Dr. Jeremy Burnham is an orthopedic surgeon in Louisiana who is specialty-trained in complex knee surgeries to address patellofemoral instability, such as transfers and osteotomies of the tibial tubercle. His main office is located in Baton Rouge and he treats patients in the Gonzales, Prairieville, St. Amant, Walker, Denham Springs, Livingston, Hammond, Brusly, Port Allen, Plaquemine, New Roads, Zachary, St. Francisville, and Lafayette areas.
- Burnham JM, Howard JS, Hayes CB, Lattermann C. Medial Patellofemoral Ligament Reconstruction With Concomitant Tibial Tubercle Transfer: A Systematic Review of Outcomes and Complications. Arthroscopy. 2016 Jun;32(6):1185-95. doi: 10.1016/j.arthro.2015.11.039. Epub 2016 Feb 13. PMID: 26882966.
- Return to Sport after Tibial Tubercle Osteotomy for Patellofemoral Pain and Osteoarthritis