Revisiting Fulkerson's Original Technique for Tibial Tubercle Transfer: Easing Technical Demand and Improving Versatility

Abstract

Tibial tubercle osteotomy is a well-described treatment option for a variety of patellofemoral disorders. Many techniques have evolved since its inception, including combinations of anteriorization, medialization, and distalization of the tibial tubercle. Although differing in their indications and end goal destination of the tubercle, these techniques share the challenging technical demands of achieving successful correction based off preoperative planning and prevention of intraoperative complications. We present our technique using osteotomy guide pins in a medial to lateral direction, originally described by Fulkerson in 1982. The advantages of our technique include better visualization for angle of osteotomy confirmation; versatility that provides options for any combination of anteriorization, medialization, or distalization; and the opportunity to maintain a distal cortical hinge if so desired.

Abnormalities of patellofemoral alignment and patellar tracking may result in patellar instability or pain. Malalignment may be attributed to trochlear dysplasia, quadriceps insufficiency, patella alta, or excessive tibial tuberosity–trochlear groove distance. Tibial tubercle osteotomy (TTO) is a well-described surgical option for treatment of a variety of patellofemoral disorders. The tubercle may be moved anterior, medial, distal, or in a combination of these directions in an attempt to normalize patellofemoral biomechanics (Table 1). Over the years, this technique has been modified to reduce the patellofemoral joint reaction forces experienced resulting in the Elmslie-Trillat direct medialization and Maquet anteriorization techniques.¹ Most recently, Fulkerson et al.² popularized anteromedialization of the tibial tuberosity. Although well described and widely used, complications of TTO continue to be reported. Minor complications described include superficial wound infections, skin irritation, and symptomatic hardware, whereas major complications include tubercle fracture, osteotomy nonunion, overcorrection, and deep infection.3, 4 Our technique, adapted from Fulkerson's original technique, provides the versatility to use any combination of tubercle medialization, anteriorization and distalization to address patellofemoral instability, maltracking, patellar height abnormality, or patellofemoral joint stresses leading to focal patella or trochlear chondral defects. In addition, this technique provides the option to maintain a distal cortical hinge.

Table 1.

Osteotomy Indications¹

Indication	Treatment
• TT-TG >20 mm	Medialize tibial tubercle
• Patella alta (CD ratio >1.2)	Distalize tibial tubercle
• Focal chondral lesion	Anteriorize tibial tubercle

NOTE. Treatments may be combined for those with multiple indications.

CD, Caton-Deschamps; TT-TG, tibial tuberosity–trochlear groove.

Surgical Technique

The patient is positioned supine on the operating table with the operative knee resting on a radiolucent triangle at approximately 30° of flexion (Table 2). A tourniquet is applied to the ipsilateral proximal thigh, although with careful dissection, inflation of the tourniquet is often not required. A single dose of prophylactic antibiotic is administered within 1 hour of skin incision. The surgical field is prepped and draped in standard surgical fashion (Fig 1A). The skin is incised in a longitudinal fashion directly over the tibial tubercle (TT), initiated 1 cm proximal and finishing 6 cm distal to the TT (Video 1). Full-thickness subcutaneous flaps are elevated to expose the medial and lateral borders of the patella tendon and identify its insertion on the TT. An electrocautery device is used to mark the medial and lateral fascial borders of the patellar tendon, with plans for an osteotomy approximately 6 cm in length (Fig 1B). Next, the muscles of the anterior compartment are elevated off the anterolateral cortex of the tibia and a retractor is placed to protect these structures. Three 2.4-mm osteotomy guide pins (Arthrex, Naples, FL) are placed colinearly in a medial to lateral direction at the desired osteotomy angle. The angle of the proposed osteotomy can now be visualized, and adjusted as needed. Again, it is important to place these guide pins colinearly, which can be confirmed using an osteotome or other flat object (Fig 1C). The near medial cortex is then scored with an oscillating saw and Stryker Sagittal Blade, narrow (Stryker, Kalamazoo, MI), along the previously set guide pins and the osteotomy is completed in a medial to lateral fashion after guide pin removal (Fig 2A). Irrigation should be used to cool the saw blade and prevent thermal injury at the osteotomy site. Here, it is the surgeon's choice to carry the osteotomy distally through the periosteum, or to leave this portion intact allowing for a distal cortical hinge. An osteotome is used to complete the osteotomy with manual elevation of the tuberosity fragment (Fig 2B). If a distalization is desired, the tuberosity fragment is removed completely and the amount of distalization in millimeters is removed from the distal aspect of the tuberosity fragment. The tuberosity fragment is then replaced flushed within the tibial bed, medially translating and/or distalizing the fragment. Replacement of the tuberosity fragment to the desired position is held in position with two 0.062 K-wires (Fig 3A). Definitive fixation of the translated tubercle is accomplished with a 3.5-mm fully threaded cortical screw on compression, using a countersink method to prevent hardware prominence (Fig 3B). The previously placed K-wires are replaced with 2 additional 3.5 mm screws in a similar fashion. The surgical field is thoroughly irrigated and a layered closure is performed in the standard fashion.

Table 2.

Surgical Steps for Tibial Tubercle Transfer

1. Position patient supine with the operative knee resting on a radiolucent triangle.

2. Make a vertical skin incision directly over the tibial tubercle (TT) from 1 cm proximal to 6 cm distal.

3. Identify and mark medial and lateral fascial borders of the patellar tendon.

4. Retract muscles of anterior compartment to expose the anterolateral cortex of the tibia.

5. Place osteotomy guide pins from medial to lateral at the angle of desired osteotomy. Ensure pins are placed colinearly.

6. Score medial cortex with oscillating saw along guide pins. Remove pins, and complete osteotomy with the oscillating saw exiting the lateral cortex.

7. The distal cortex may be completed or left intact as a hinge.

8. Elevate the tuberosity fragment with an osteotome.

9. Translate tuberosity fragment to desired position and hold into place with 0.062 K-wires.

10. Fix fragment in position with 3.5-mm fully threaded cortical screws on compression, using a countersink to prevent hardware prominence.

11. Layered closure in standard fashion.

12. Place patient into a hinged-knee brace.

Fig 1.

(A) Setup for right-sided tibial tubercle osteotomy. Patient is positioned supine on the operating table with the operative knee resting on a radiolucent triangle at approximately 30° of flexion. The surgical field is prepped and draped in standard surgical fashion. The skin is incised in a longitudinal fashion directly over the tibial tubercle, initiated 1 cm proximal and finishing 6 cm distal to the tibial tubercle. Patient supine, right leg, head to the left of the image. (B) An electrocautery device is used to mark the medial and lateral fascial borders of the patellar tendon, with plans for an osteotomy approximately 6 cm in length. Patient supine, right leg, head to the left of the image. (C) Three osteotomy guide pins are placed colinearly in a medial to lateral direction at the desired osteotomy angle, and the angle of the proposed osteotomy can now be visualized. Patient supine, right leg, head to the left of the image. (TT, tibial tubercle.)

Fig 2.

(A) The near medial cortex is then scored with an oscillating saw along the previously set guide pins, and the osteotomy is completed in a medial to lateral fashion. Patient supine, right leg, head to the top of the image. (B) An osteotome is used to complete the osteotomy with manual elevation of the tuberosity fragment. Here, it is the surgeon's choice to carry the osteotomy distally through the periosteum, or to leave this portion intact, allowing for a distal cortical hinge. Patient supine, right leg, head to the top of the image. (TT, tibial tubercle.)

Fig 3.

(A) The tuberosity fragment is then replaced flush within the tibial bed, medially translating and distalizing the fragment. Patient supine, right leg, head to the top of the image. (B) Definitive fixation of the translated tubercle is accomplished with a 3.5-mm fully threaded cortical screw on compression, using a countersink method to prevent hardware prominence. Patient supine, right leg, head to the right of the image. (TT, tibial tubercle.)

We recommend preoperative planning to calculate patellar height with Caton-Deschamps ratio and patellofemoral tracking with tibial tuberosity–trochlear groove distance. The amount of desired distalization is calculated to decrease the Caton-Deschamps ratio to 1.1 and medialization is calculated to decrease tibial tuberosity–trochlear groove distance to 12 mm (Table 3). If anteromedilization is performed, the angle of osteotomy and amount of translation can be calculated using right-triangle trigonometry (Fig 4).

Table 3.

Pearls and Pitfalls

Pearls	Pitfalls
• Preoperative planning with goal correction of Caton-Deschamps ratio to 1.1 and TT-TG to 12 mm	• Failing to define borders of patellar tendon
• Specific patient positioning	• Small, thin TT fragments increase fracture risk of the tubercle fragment
• Use of properly placed Raytec surgical sponges and electrocautery in the lateral and medial subcutaneous flaps rather than a tourniquet for hemostasis control	• Thermal injury at osteotomy site may lead to delayed or nonunion
• Use of large, broad retractor along the lateral tibia for soft tissue protection from the surgical saw	• Failing to line up guide pins will lead to uneven cut and irregular surface at osteotomy site
• Confirm the angle of the prepared osteotomy prior to cutting by visual inspection with an osteotome balanced on the colinear guide pins (Fig 1C)	• Failing to countersink screws may lead to prominent and painful hardware, though these can be removed after definitive union
• Use of an oscillating saw to minimize the risk of tubercle or proximal tibial fracture5
• Completion of the lateral osteotomy compartment with a curved osteotome
• Use of an Army-Navy retractor to protect the patellar tendon during osteotome completion of the proximal osteotomy
• Use of countersinking 3.5-mm fully threaded cortical screws to reduce the risk of prominent symptomatic hardware

TT, tibial tubercle; TT-TG, tibial tuberosity–trochlear groove.

Fig 4.

The angle of osteotomy and amount of translation can be calculated using right-triangle trigonometry. Axial illustration of left tibia. (TT, tibial tubercle.)

Discussion

TTO is a well-described procedure used for realignment of the extensor mechanism. The development of varying techniques, including medialization, anteriorization, and distalization of the TT have provided opportunities to reduce joint reaction forces and realign problematic contact areas in the setting of patellofemoral joint disorders.²

Clinical studies have shown excellent long-term outcomes with TTO for a variety of patellofemoral maladies.⁶ In their study of recurrent patellar instability, Nakagawa et al.⁵ found that 91% of knees treated with direct medialization of TT reported good or excellent Fulkerson knee scores at 45 months postoperatively. Deterioration of scores after 10 years was due to progressing joint pain, rather than recurrent instability. Diks et al.⁷ found that 81% of knees with patellar maltracking treated with medialization, with or without distalization, had good pain relief at an average of 37 months postoperatively. Patients with patellar articular cartilage lesions have also demonstrated significant pain relief after anteromedialization of the TT, with 100% reporting they would repeat the procedure.⁸ Using a novel, self-centering technique in patients with either maltracking or instability, Tigchelaar et al.⁶ reported maintenance of good results with regard to functional outcomes and decreased pain scores 10 years postoperatively, without statistically significant increases in the development of osteoarthritis. However, TTO is not without risk of complications. Via systematic review, Payne et al.⁴ found that the overall risk of osteotomy site nonunion was 0.8%, the overall risk of tibial fracture was 1.0%, and that the risks of these poor outcomes more than doubled when the TT was completely detached.

Our technique is advantageous for both the surgeon and patient. Unobstructed visualization with the described approach allows the surgeon to easily plan and appropriately adjust for the desired osteotomy angle. Additionally, this technique empowers the surgeon with the versatility to achieve virtually any combination of previously described TT transfers, including medialization, anteriorization, and distalization. Once an angle and transfer destination has been chosen, the resultant large, flat cortical tubercle segment allows for satisfactory compression along the osteotomy site and rapid healing of the apposed cancellous surfaces. This technique also provides the option for maintenance of the distal cortical hinge, thereby reducing the risk of osteotomy site nonunion and tibial fracture described by Payne et al.⁴

Supplementary Data

Video 1

Tibial tubercle transfer in a right knee, with the patient lying supine, with osteotome guide pins in a medial to lateral direction used to determine angle of osteotomy.