This is Dr. Jack Farr. I'll be discussing tibial tubercle osteotomies, indications, and techniques. I have financial disclosures, and these are on the AOS website. Tibial tubercle osteotomies are rarely performed as an isolated procedure, and therefore, the indications are based upon subsets, including pain, recurrent patellar instability, and pain with recurrent patellar instability. As we all know, patellofemoral pain is a complex and difficult problem. In fact, assigning pain to chondrosis is, by definition, a diagnosis by exclusion, as articular cartilage is a neural, and therefore, the pain must be coming from the bone, soft tissues, or nerves. Likewise, instability is often complex and multifactorial, and certainly, in 2020, an isolated tibial tubercle osteotomy is not indicated as a sole procedure for recurrent patellar instability. So the keys in helping these patients are to identify each risk factor that the patient has, assign the importance of each risk factor, and then normalize the risk factors as to affect a stable patella without chondral overload, as was experienced with the ill-fated Hauser procedure. This approach allows minimizing surgical morbidity, and we want to do the least possible to obtain an optimal result. The most common patellofemoral tibial tubercle osteotomies are straight medialization. This would be performed if there is chronic patellar oscillofixation, or Andrew Amos has shown us in the lab that it's very difficult to have the correct length changes if the TTTG is greater than 15. So that would be performed in conjunction with MPFL, knowing that straight medialization would only be performed if there is minimal or no chondrosis. Straight anteriorization was popularized in the past by McKay. Fulkerson has modified this, but they're both elevating the tibial tubercle straight anteriorly, and biomechanical studies, the most recent of which came out of Rush with first author Rue, demonstrated that the mechanics with a straight anteriorization of 15 millimeters allows for a decrease in patellofemoral loading at peak force between 20 and 30%. Distillation is popularized by Fulkerson, is optimal as an isolated procedure for a distal lateral or distal lesion, and if there are other areas of chondral damage, then cartilage restoration would need to be added. Finally, in certain cases, distillization is indicated for those with extremes of patellar alta, at least greater than 1.4 cation ratio, and proximalization is only suggested when the result of the patella infera is just because of scarring and not because of generalized arthrofibrosis. This is a chondral map that will aid in deciding when to add cartilage restoration to an anteriorization. P. Doriano and Fulkerson reported good and excellent results with distal and distal lateral lesions, but less optimal results with panpatellar, medial, proximal, or if the trochlea was concomitantly involved. And in those cases, we would now currently add cartilage restoration to the procedure. I'll go through these procedures, the actual technique. First, I'd like to mention that with medialization that is common to many of these, there will be increased tension within the lateral retinaculum. To decrease this tension and still maintain control, I would suggest evaluating a lateral lengthening. This is a step cut lengthening between the superficial oblique layer of the lateral retinaculum and the deep transverse layer. The deep transverse layer is entered between 1.5 and 2 centimeters posterior to the lateral border of the patella. You can see these two layers. They can then be sutured end to end, affecting a 1.5 to 2 centimeter lengthening. This compares anterior medialization to tibial tuberosity medialization. In this case, this is the steepest slope possible. It would be 60 degrees. With that, 15 millimeters of anteriorization yields 8.7 millimeters of medialization. This is an example of anterior medialization in a patient with chronic patellar subluxation. They do not have instability, but they do have chondrosis that we will unload with the anterior medialization. In this case, a guide is used to select the slope. Many advanced surgeons can perform this in a freehand manner or just using reference pins. In this case, the cutting block, after it's secured, allows use of an oscillating saw cooled with saline to affect the slope cut. This is an alternative AMZ jig system. Note that I was involved as a design surgeon for both of the commercially available devices. After completing the oblique osteotomy initially, that cut is then used as a quote, captured guide, end of quote, to affect completing the proximal and distal aspects of the slope cut. And then the proximal cuts are made with two osteotomes at different angles. The first connects the posterior cut to the lateral margin of the patellar tendon attachment to the tubercle. And then the angle is changed to a more lateral to medial to allow completion of the osteotomy. As you can see, the slope cut is now completed and the pedicle is free. This allows for cancellous to cancellous healing. It is typically fixed with interfragmentary screw fixation, and in this case, seven millimeters of medialization was associated with 15 millimeters of anteriorization. Post-operative radiographs demonstrate adequate position of the tubercle and centralization of the patella. This is an example of straight medialization. Prior to planning surgery, the patient underwent an axial CT to be sure there was not excessive lateral position of the tubercle on the basis of femoral antiversion or tibial torsion. In this case, it was isolated tuberosity position lateral. In the open procedure, you can certainly appreciate the amount of lateral position of the tubercle. An incision is made along the lateral border of the patellar tendon and then along the patellar tendon as it is on the tubercle and crest. An incision is made at the anterior border of the anterior cabarma musculature, which is then elevated for approximately 1 to 1.5 centimeters. The first cut is in the axial plane, just proximal to the patellar tendon attachment to the tubercle. The second cut is approximately 1.5 centimeters posterior to the anterior aspect of the tubercle and courses from lateral to medial in the coronal plane. The distal aspect remains intact. With osteoclasis, it's possible to rotate the tubercle medially, where it is then fixed with interfragmentary screw fixation. In this case, it was medialized approximately 10 millimeters. Distalization is indicated for treating extremes of patellar alta. That is typically with ketone ratio of greater than 1.4. In this case, a V-shaped cut is made. Measurement is completed to affect normalization. Certainly, we do not want to over-distalize. The cut is made, taking into account loss of bone with the kerf of the saw. It is then replaced into the cancellous bed and fixed with interfragmentary screw fixation. Some surgeons will perform a proximal tenodesis in the region of the original site of the tendon to decrease the potential, quote, window washer effect. Other surgeons will add bone proximal to this in an effort to decrease the stress on the screws. This is an example of a patient with 1.4 ketone ratio initially, and then distalized to a more normal ketone ratio of 1.0. Proximalization of the tubercle is indicated when there is patella infra that is not a result of patella infracontraction syndrome. That is, there's not generalized arthrofibrosis. In this case, an intermedialization pedicle has been performed and there is skeletalization of the proximal aspect for 1.5 to 2 centimeters. This will allow proximalization of the tubercle, but without creating the tubercle being too close to the joint line, which would complicate future arthroplasty surgeries. This is an example of post-fracture distalization of the patella. To the right, you can see after the proximalization, the ketone ratio is more normalized and the patient's function improved. Finally, we'll discuss straight enterization with Fulkerson's modification of the MacKay. The lateral wall is exposed and the posterior nervosclerostructures are protected with a retractor. A mark is made on the saw so that you are able to complete the osteotomy to, but not through, the posterior cortex of the tibia. It's important to correct rotation. Most patients will be slightly external or rotated when relaxed under anesthetic. So they're brought to neutral and then with the saw held perpendicular to the table, an anterior to posterior cut is completed, cooling it with saline. Once again, it is to, but not through, the posterior cortex. The lateral wall is then cut with a 90 degree saw. This is five millimeters anterior to the posterior cortex. The saw is also used to make the distal cut. The proximal cuts are made in the same manner as for an anterior medialization. This frees the pedicle. And as you can see, the posterior cortex does remain intact. There is a straight enterization, which is then fixed with interfragmentary screws, typically two or three running from lateral to medial. And in this case, there was 1.5 centimeters of straight enterization. Post-operative radiographs demonstrate adequate enterization and healing. Post-operative rehabilitation is extremely important. Patients need to understand the rationale for adhering to weight bearing status. With a completed osteotomy, such as anterior medialization or straight anteriorization, it is necessary to be minimal weight bearing with two crutches for six weeks. The straight medialization with the osteoclasis allows earlier weight bearing as tolerated, and typically they can exit crutches within four weeks. Early range of motion is important throughout, as is early core to floor rehabilitation. With this attention to detail, it's possible to have good and excellent results from each of these procedures. Thank you.

tibial tubercle osteotomy

patellar instability

patellofemoral pain

surgical techniques

post-operative rehabilitation