Lateral Retinacular Lengthening Alongside Distalization TTO and Medial Ligamentous Complex Reconstruction: A Technical Note

Video Transcript

Hello, and welcome to our technique video on conducting a lateral retinacular lengthening alongside a distalizing tibial tubercle osteotomy (TTO) and medial ligamentous complex reconstruction.

Background

We will begin by discussing the indications for this case. This patient is a 19-year-old man who dislocated his right patella 2 months prior with a twisting injury while skateboarding. He trialed 1 month of physical therapy but continued to have anterior knee pain, instability, and apprehension. The following findings indicated the procedures performed:

Shown here are radiographs from this patient demonstrating patella alta as evidenced by an increased CDI and a wink sign.

Shown here are MRI slices demonstrating a mildly increased TT-TG distance, increased lateral patellar subluxation and tilt, trochlear dysplasia, and a knee effusion.

Indications

Before we begin, we will review the anatomy of the lateral patellar retinaculum, which provides soft tissue balance and allows for normal medial patellar excursion without causing lateral patellar laxity. It contains 2 layers, superficial and deep, both of which are located superficial to the joint capsule of the knee. The superficial layer is composed primarily of longitudinally and obliquely directed fibers of the iliotibial band. The deep layer is composed of deep fibers of the iliotibial (IT) band, the vastus lateralis, the lateral patellofemoral ligament, the lateral patellotibial ligament, and the lateral meniscal ligament. In a lateral retinacular lengthening procedure, these 2 layers are dissected away from each other, incised, and the free ends are stitched together to create a lengthening effect.^7,12,13

Technique Description

The procedure began with the patient placed in the supine position on the operating room table, a tourniquet applied to the operative thigh, and posts placed on the side of the bed to allow for positioning of the knee in 30° and 90° of flexion.

A clinical knee examination was conducted, demonstrating increased lateral patellar mobility in both flexion and extension. Then, the contralateral limb was secured to the table, and the operative extremity was prepped and draped using standard sterile technique.

The presence of important instruments was confirmed, as follows:

To begin, a diagnostic arthroscopy was performed via standard anterolateral and anteromedial portals, with a single foreign body located and removed from the lateral gutter in this case.

After the arthroscopy, a midline skin incision was marked and made from the quadriceps tendon to just distal and lateral of the tibial tuberosity. Full-thickness fasciocutaneous flaps were raised medially and laterally. An incision was then made adjacent to the patella through the superficial oblique fibers of the patellar retinaculum only and extended proximally to the level of the IT band.

A scalpel blade was then used to develop a plane approximately 2 cm in the posterior direction between the superficial oblique layer and the deep transverse layer of the retinaculum. The deep transverse fibers were then incised, preserving the joint capsule in the process.

Here, note the medial deep layer and the superficial lateral layer, with the joint capsule located underneath both. The 2 free ends of these layers were then approximated end-to-end with multiple interrupted No. 1 Vicryl sutures. This approximation affected the lateral lengthening and allowed centralization of the patella.

Here, one can note the 2 joined layers of the lengthened retinaculum.

Attention was then turned to the tibial tuberosity. Electrocautery was used to delineate the lateral border of the osteotomy, and the patellar tendon was then identified and isolated by medial and lateral incisions adjacent to the tendon. The tendon was then protected with retractor placement.

This picture demonstrates the isolated tendon.

An oblique cut resulting in a 6 to 8 cm pedicle and directed 30° to 45° to the sagittal plane was planned, with the cut directed more deeply in the anterior tibia at the proximal end and more distally at the superficial end. After measuring the cut length, electrocautery was again used to delineate the medial side of the TTO, with the markings visible here.

The osteotomy began using the 30-mm fan blade on the oscillating saw with cold irrigation, directed from medial to lateral. The precision thin blade and osteotomes were then used to complete the cut. When necessary, the saw blade was also used on the lateral side to complete the cut between the Gerdy tubercle and the tibial tuberosity pedicle. Remember to use caution when working behind the patellar tendon and use the small saw and osteotomes to avoid injury to the tendon itself.

After the cut was completed, the tuberosity pedicle was directly distalized approximately 8 mm, and the patellar height was checked with fluoroscopy.

Three K-wires were then placed to provisionally fix the tuberosity pedicle to the tibia, with these placed in the order of middle, proximal, and distal for maximal stability. These K-wires were also directed anterolateral to posteromedial to optimize compression and protect posterior neurovascular structures.

After taking the knee through a full range of motion to ensure patellar stability in all degrees of flexion, three 5-mm compression screws were placed. The depth of each K-wire was measured, and a starting drill bit was placed over the K-wire and used to penetrate the first cortex. Then, a standard drill bit was swapped out and used to complete the drilling. Screws were placed beginning under power and then completed using hand turns. Care was taken during this step to avoid damaging posterior neurovascular structures when drilling the posterior cortex.

Here, we confirm that the tibial tuberosity does not lie medial to the patella. This step is necessary because the tibial crest becomes more medial as one travels distally along the tibia, and so aligning the osteotomy with the medial border of the crest automatically medializes the tuberosity.

The knee was again taken through a full range of motion with confirmation of central patellar tracking and stable fixation. Finally, the proximal gap of the osteotomy created by distalization was filled with calcium phosphate substrate.

After the distalizing osteotomy was complete, the MPFL, MPTL, and MQTFL were reconstructed using previously described techniques using a frozen tibialis anterior allograft and suture anchors.

Results

Outcomes for this combined and multistep procedure can be improved by following the proper technique.

For the lateral retinaculum (LR) lengthening, anatomy is critical, as previously mentioned. Careful identification and differentiation of the superficial and deep layers of the LR, as well as avoiding entry into the joint capsule, helps ensure joining of the proper layers and improves outcomes. ¹⁶

During the TTO, a tapered cut decreases the risk of tibia fracture, increases safety for the patient, and improves healing.

Tapered cuts also allow for intraoperative adjustment of patellar height by adjusting the position of the tuberosity, while a step cut limits where the osteotomy can be placed. Distalization by 6 to 10 mm is typically ideal to normalize the CDI. Finally, filling the proximal gap of the osteotomy with calcium phosphate serves to buttress the osteotomy against proximal forces, maintaining the reduction and reducing stress on the screws. ¹⁰

Screw placement is also very important during the TTO. An oblique cut angled at 30° to 45° improves healing rates and allows for optimal screw placement. These screws should be placed in the anterolateral to posteromedial direction, perpendicular to the cut. This provides strong compression for healing and protects posterior neurovascular structures, as seen in the computed tomography image in the figure. ⁴

Additionally, placing the K-wires and subsequent screws in the order of middle, proximal, and distal provides maximum stability during placement. Three screw constructs protect against retraction of the strong patellar tendon and tuberosity.

Discussion/Conclusion

Ultimately, a well-considered postoperative plan, combined with effective physical therapy, is crucial. ⁸ We place our patients in a hinged knee immobilizer locked in 10° of flexion for 24 hours a day for the first 4 weeks, with crutches for 50% weightbearing. Physical therapy or a continuous passive motion machine can be used for the knee range of motion up to 90° of flexion (L Niemuth, E Arendt, unpublished guidelines, January 2025).

At around 4 weeks, patients can gradually increase their weightbearing while in the brace until they no longer need crutches, while also progressively unlocking the brace to increase their flexion. The brace can be removed while sleeping.

By 8 weeks, patients should exhibit radiographic signs of early union, along with increased quadriceps strength, and their brace can be exchanged for a knee sleeve. They can continue full range of motion of the knee and engage in low-impact exercises, such as biking.

At 3 months postoperatively, patients should be working to restore normal joint mechanics. Strengthening is key at this stage, especially with quadriceps and core exercises to help prevent future patellar dislocations.^7,11

Most patients return to their activities or sports around 4.5 to 6 months postoperatively, depending on their individual recovery progress.