Anteromedial Tibial Tubercle Osteotomy for Recurrent Patella Subluxation

Abstract

Background:

Patellofemoral pathology resulting from improper biomechanics is difficult to treat, and lateral patellar instability requires individualized treatment, which may include tibial tubercle osteotomy (TTO) with anteromedial repositioning.

Indications:

Symptomatic patellofemoral instability with maltracking, particularly in cases with a tibial tuberosity-trochlear groove distance >16 mm.

Technique Description:

We describe an oblique osteotomy from medial to lateral. A careful completion of the osteotomy is made with an osteotome, and the resulting fragment is mobilized to achieve anteromedial repositioning—as well as distalization in cases of patella alta. Two bicortical screws with a washer are used for fixation of the tibial tubercle following anteromedialization.

Results:

Systematic reviews demonstrated that the treatment of the lateral patellar instability requires an individual treatment and the anteromedial TTO is a very important procedure alone or in association with medial patellofemoral ligament.

Discussion/Conclusion:

Recurrent lateral patellar instability is a challenging condition with complex causes and various treatment options, but anteromedial TTO provides an effective way to improve clinical outcomes and correct patellar maltracking, with relatively low complication rates.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This is a video case presentation of Tibial Tubercle Osteotomy (TTO) for Recurrent Patella Subluxation. Our conflicts of interest can be seen here.

Patellofemoral pathology resulting from improper biomechanics of the patellofemoral joint is rather difficult to successfully treat and ultimately results in considerable anterior knee pain and instability of the joint. ⁵

Given the many potential sources of patellar instability, proper treatment of lateral patellar instability differs on a patient-to-patient basis. Various treatment methods, ranging from nonoperative to minimally invasive to aggressive in nature, have been described. However, in cases of chronic instability with a lateralized tibial tubercle, medial patellofemoral ligament reconstruction (MPFLR) will not suffice and correction of patellofemoral alignment is necessary. ¹²

The MPFLR alone produces no improvement in patellar tilt or shift. ² As demonstrated in this study, 10 patients with patellofemoral instability referred to isolated MPFLR surgery were selected and subjected to dynamic computed tomography before and ≥6 months after surgery. ⁶

Furthermore, malalignment may be attributed to trochlear dysplasia, quadriceps insufficiency, patella alta, or excessive tibial tubercle-trochlear groove (TT-TG) distance. ⁵ TTO is a well-described surgical option for treatment of a variety of patellofemoral disorders. ¹ A TTO with anteromedial repositioning, more popularly known as Fulkerson osteotomy, is a popular technique undertaken to correct patellofemoral malalignment. And these are the classic indications and treatment options: you must medialize TT-TG higher than 20 mm, distalize patella alta—Caton-Deschamps index higher than 1.2, and anteriorize focal chondral lesions. ³

Here are some benefits of Fulkerson in relation to Elmslie-Trillat technique: (1) enhances the extensor mechanism increasing its lever arm, (2) decreases total patellofemoral contact pressure, (3) changes the area of patellofemoral contact and decreases overload on the lateral and distal part of the patella. ¹⁰

Case presentation: A 22-year-old woman presented with a history of recurrent patellar dislocation since the age of 7. She reported multiple subluxations of her right knee over the years and complained of ongoing anterior knee pain. Physical examination revealed positive ligamentous laxity and a Beighton score of 5. However, her knee alignment was normal and there were no femoral or tibial rotational disorders.

Imaging studies showed a Caton-Deschamps index of 1.15. The TT-TG distance was 22 mm. The trochlear groove was classified as Dejour type C. In addition, there was a patellar distal-lateral chondral lesion, graded as Outerbridge 2. In this video, we note the “J sign” of this patient in her right knee.

Here we visualize a sawbone model for planning technique. With the use of a ruler, the site of the osteotomy is measured. From medial to lateral, three 4.5-mm K-wires are placed in the proximal aspect of the tibia in an oblique position parallel to one another. A small oscillatory saw is used to perform the osteotomy. In the sawbone models, we can see a proximal and transverse osteotomy—completed with an osteotome. In this case, we simulated 10 mm of anteromedialization. ¹⁴

That is the final aspect of the Fulkerson TTO. If anteromedialization is performed, the angle of osteotomy and amount of translation can be calculated using right-triangle trigonometry as demonstrated.^11,14 If the surgeon performs a >55° osteotomy, a “step cut” is needed. This is an illustration of the “step cup” and a second case example where this technique was performed. ¹¹

Surgical technique: Here, a longitudinal incision approximately 8 to 10 cm in length just lateral to the tendon was performed to adequately expose the patellar tendon.

Now we demonstrate how the anterior compartment musculature is dissected exposing the posterolateral margin of the tibia. In this medial view with the use of an electrocautery, the site of the osteotomy is delimited.

Then, three 4.5-mm K-wires are placed in the proximal aspect of the tibia in an oblique position (45° angle) with care taken to carefully place the K-wires parallel to one another. The degree of obliquity can be modified, depending on the amount of anteromedialization required. ¹⁸

The 3 K-wires are snapped off to allow the surgeon to hold the saw closer to the bone and a lateral protector in place to the neurovascular structures. A half-inch osteotome is then carefully used to complete the osteotomy while a potential fracture of the proximal tibia or portion of the tibial tubercle to be translated is avoided. The amount of medialization is confirmed with the use of a ruler, in this case, 10 mm. The degree of anteromedialization is achieved and held in place with provisional K-wires and a good tracking position is confirmed before the fixation.

After this, two 4.5-mm screws are then fixed into the tibial tubercle in a bicortical fashion for better fixation, and a washer is used to avoid fractures. Using OEC imaging, the position of the screws is confirmed. After the end of the operation, a knee flexion-extension is performed to confirm the ideal patellofemoral tracking, noting the absence of J sign.

Here is an OEC imaging to show the amount of anteriorization. Now, the operative pearls are exposed: define borders of patellar tendon, subperiosteal dissection of the anterolateral compartment, draw the medial cut with electrocautery, use at least 3 K-wires to guide the osteotomy with saw blade (and cut them short for easier use of the saw blade), protect the neurovascular structures while cutting the lateral tibia (they are just anterior to the interosseous membrane), and complete the transverse proximal osteotomy with an osteotome using a retractor to protect the patellar tendon.

Proper postoperative rehabilitation is crucial following TTO. Here are some key factors to consider during the recovery process:

Weightbearing is limited to toe-touch or no weight during the first 6 weeks; after that weightbearing as tolerated is progressed until crutches are discontinued by 8 weeks or when adequate gait control is achieved.

Range of motion (ROM): Exercises focused on restoring ROM can be started immediately after surgery 0° to 90° for 4 weeks and unrestricted after that. ⁹

From the first postoperative day, exercises focused on patella mobilization, quadriceps, and hamstring muscle reactivation should be encouraged. Progressive strength and proprioceptive training can be allowed after 8 weeks. ⁹

The TTO is associated with a 1% to 3% rate of tibial fracture—only with early full-weightbearing less than 6 weeks, and 1% rate of nonunion. ⁷ Early weightbearing and complete detachment of the distal tuberosity may increase these risks. Painful screws requiring removal occur in 3% to 14%. ¹⁷ Recurrent instability occurs in ±5% of cases at least 5 years. ¹³

This prospective comparative study was conducted to compare the functional outcomes and patellar tracking of patients with recurrent patellar instability and a TT-TG distance of 17 to 20 mm who underwent either TTO+MPFLR or MPFLR alone (MPFLRa). A total of 42 patients were included in the study, with a mean follow-up of 40.86 months. The results indicated that TTO+MPFLR resulted in better functional outcomes scores and patellar kinematics compared with MPFLRa. ⁴

Another retrospective, comparative, and prognostic trial with the purpose to compare postoperative complication rates between patients who underwent MPFLR and those who underwent MPFLR with TTO was conducted. Patients who underwent MPFLR (n = 3480) or MPFLR-TTO (n = 615) were compared and results with an MPFLR cohort exhibiting higher rates of revision surgery at 2 years (1.9% vs 0.8%; odds ratio, 0.33; 95% confidence interval, 0.10-0.80; P = .036) were compared with the MPFLR-TTO cohort. ¹⁶

Furthermore, this systematic review and this cohort study indicate that MPFLR+TTO outcomes and risk profiles are similar to those of isolated MPFLR. Also these 3 systematic reviews demonstrate the benefits of the TTO with better outcome measures for patellofemoral instability, ¹⁷ good outcomes for patellofemoral malalignment and chondral disease, and good results for patella distalization in patella alta cases.^8,15

Recurrent lateral patellar instability is a challenging condition to treat because of the variety of causes and complex biomechanics inherent to the patellofemoral joint. Chronic maltracking leads to lateral and inferior patella cartilage lesions. Anteromedial TTO corrects maltracking, enhances extensor mechanism increasing its lever arm, decreases patellofemoral contact pressure, and unloads lateral and inferior patella regions. In conclusion, this technique improves patellar instability treatment, especially in patients with increased TT-TG, high patella, and patellofemoral cartilage lesion secondary to maltracking.

Here are our references. Thank you.