Patellofemoral Instability: Video Presentation of MPFL Reconstruction and TTO Distalization Part 2—Lateral Lengthening and MPFL Reconstruction

Abstract

Background:

Patellofemoral instability is a common problem that requires personalized treatment for each patient based on the relevant pathoanatomy. There are many ways to perform soft tissue and osteotomy procedures, and here we present our lead author's treatment algorithm, operative technique, and postoperative protocol.

Indications:

Medial patellofemoral ligament (MPFL) reconstruction, vastus medialis obliquus (VMO) advancement, and MPFL repair are indicated in patients with unsuccessful nonsurgical treatment after primary dislocation, those with significant osteochondral fracture, and patients with excessively high-risk factors after primary dislocation. Osteotomy is a consideration in those with elevated tibial tuberosity–trochlear groove (TT-TG) or patellar alta, while lateral retinacular lengthening is indicated for those with lateral patellar tilt.

Technique Description:

In part 2 of this 2-part series, we demonstrate the soft tissue components of this case, including lateral retinacular lengthening, MPFL reconstruction, VMO advancement, and MPFL repair. Lateral retinacular lengthening is shown to correct patellar tilt and allow for eversion of the patella. Once adequately lengthened, MPFL reconstruction is performed to enable a checkrein to resist lateral translation, particularly in 0° to 30° of flexion, before the patella engages the trochlea. Native MPFL imbrication is performed to further reinforce the reconstruction, and VMO advancement allows for dynamic medialization force.

Results:

Patients can expect improved clinical and functional outcomes with tibial tubercle osteotomy (TTO) when appropriately indicated, with reliable patellar stability and low rates of complications.

Discussion/Conclusion:

In patients with an elevated Caton-Deschamps Index >1.4 or TT-TG >20, TTO can lead to very high patient satisfaction, improved clinical outcomes, and low re-dislocation rates. Even in patients with a “gray” zone TT-TG of 17 to 20 mm, Level II evidence has shown improved patient-reported outcomes with the addition of TTO.

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

Background

This is a case presentation on a patient with patellofemoral instability with a video technique guide on medial patellofemoral ligament (MPFL) reconstruction and tibial tubercle osteotomy (TTO) with medialization and distalization. This video comprises part 2 of a 2-part series.

In this video, we will show the surgical video technique of lateral retinacular lengthening, MPFL reconstruction, and vastus medialis obliquus (VMO) advancement with MPFL repair. We will discuss our postoperative protocol, expected outcomes from this procedure, and final outcome for this patient.

There are no relevant disclosures in this technique presentation and those listed here related to the primary author.

Indications

To review, we have a 15-year-old girl with recurrent patellofemoral instability that is worse in the left knee than the right. She also has severe patellar alta, an elevated tibial tuberosity–trochlear groove (TT-TG), and unsuccessful nonoperative treatment.

The plan is for left knee diagnostic arthroscopy with lateral retinacular lengthening, MPFL reconstruction using an autograft hamstring, VMO muscle advancement with MPFL repair, and TTO with distalization of 2 cm and medialization of 1 cm.

Diagnostic arthroscopy and TTO have been completed, and now we will turn our attention to the soft tissue procedures.

Technique Description

The patient's lateral retinaculum is exposed through a 4-cm incision, which is carried in line proximally from the inferolateral portal incision until roughly 1 cm proximal to the superior border of the patella.

Two Army-Navy retractors are placed laterally, with proximal to distal spread. A sharp Senn retractor with teeth is placed on the medial side of the patella. This allows for good tension on the tissues. The lateral retinaculum is then dissected out and exposed with the use of Metz scissors, and blunt dissection is utilized via a Ray-Tec and rat tooth to complete exposure.

The superficial retinaculum layer is divided just lateral to the patellar attachment, and the layer is separated from the underlying capsule, a thin grayish membrane. There can be some potential suprascapular adipose overlying the capsule. Dissecting these layers is all about tension with an Army-Navy retractor toeing into the retinaculum to pull the retinaculum away from the capsule to enable blunt and Mayo dissection between the 2 layers.

The capsule is then marked out and can be incised vertically between 1 and 2 cm lateral to the patellar border. The amount of lengthening is dependent upon the degree of tilt and the degree of tightness. For this patient, we chose 2 cm. The superior extent of the capsulotomy is the vastus lateralis to prevent hematoma, and the inferior extent is limited by the meniscus. After this release, you should now be able to successfully evert the patella. If not, you can release the vastus lateralis fascia over the muscle fibers and release the meniscal patellar ligaments by using Mayo scissors to clip between the meniscus and capsule within the fat pad distally and medially while putting medial pressure on the patella to place these ligaments under tension. The deep medial capsule edge and the superficial lateral retinacular edge are then repaired end-to-end with a running suture, 0 Vicryl (Ethicon). Small bites are used to prevent shortening.

Next, we proceed with MPFL reconstruction. The medial flap of the lateral parapatellar incision is evaluated to expose to 3 cm beyond the medial border of the patella. This should expose all the way down to where the medial epicondyle and Schottle's point are estimated to be.

Next, we work to expose the medial retinaculum and VMO. Two sharp Senn retractors are used medially to lift the medial flap, and Metz scissors are used to spread on top of the patella and arrive at the medial border just superficial to the retinacular layer.

The Senn retractors are switched out to 2 Army-Navy retractors medially and a sharp Senn retracting the patella laterally. The medial retinaculum is incised and exposed roughly from the superior pole of the patella to just distal to the midpoint of the patella. This retinaculum is undermined medially with Metz scissors and a Kelly clamp.

Next, we dissect out the native MPFL. An incision is carried through the retinaculum from medial inferior to lateral superior on top of the distal extent of the VMO to the medial border of the patella at the superior pole. This is the upper extent of a flap that contains the retinaculum with the MPFL and the medial quadriceps tendon femoral ligament (MQTFL). The leading edge of VMO fascia is tagged with a No. 1 Vicryl double pass for later VMO advancement.

Now, roughly 2 cm distal, another incision is carried in the same orientation, parallel to the first. The tissue attachment is then elevated off the medial border of the patella via the prior split in the retinaculum and lifted, containing the MPFL, overlying retinaculum and the MQTFL as a rectangular flap of retinaculum. The capsule remains intact underneath. This retinacular flap with the MPFL is then Krakow stitched from lateral to medial along the superior border and from medial to lateral along the inferior border with a 2-0 Ethibond (Ethicon).

Here you can see that the remnant MPFL has enough excursion to reach the midpoint of the patella, indicating the significant attenuation and incompetence of the tissue. This will be addressed with imbrication of this tissue later on in the case.

A bump is placed under the knee to aid in fluoroscopic imaging. Next, the anatomic femoral attachment of the MPFL on the femur is identified using fluoroscopy. A perfect lateral is obtained, showing as much of the distal femur as possible to allow for better assessment of the posterior femoral cortical line. The femoral origin of the MPFL is distal to the physis, but given the undulation of the physis, on the lateral radiograph, Schottle's point will appear proximal to the physeal reflection. This is demonstrated in these images from a different case. A Kelly clamp is used to identify Schottle's point in this patient.

A sharp incision is made at Schottle's point. A Beath pin is placed at this site, and a tunnel is drilled exiting the femur superior and anteriorly. For pediatric patients with open physes, this procedure can be performed distally and anteriorly under fluoroscopy to avoid the distal femoral physis.

Once drilled, a Kocher clamp is placed against the bone to show where the aperture is. This is confirmed one last time on fluoroscopy. Next, a blind socket is reamed to about 25 to 30 mm through the soft tissue guide, with a size that correlates with the folded diameter of the graft. Fluoroscopy is utilized during reaming to ensure adequate socket depth and avoid damaging the physis in skeletally immature patients.

Our preference is to use hamstring autograft for MPFL reconstruction. The semitendinosus is harvested using a standard technique at the outset of the procedure and has already been prepped on the back table, as shown here.

A long interference screw guide pin is then inserted into this tunnel to aid the eventual use of the interference screw once the graft is placed. The passing stitch on the femoral side of the graft is passed through the Beath pin and shuttled into the femur using a vice grip on the Beath pin and a mallet. A 7 × 23-mm interference screw is then placed in the femoral tunnel on the folded end of the autograft. The graft is then passed to the medial patella.

The knee is now flexed 30° over a bolster to engage the trochlea. A groove is created at the patellar attachment of the MPFL, deep to the overlying retinaculum, with the Bovie down to the bone edge. Next, a large tenaculum is used with teeth medial to lateral and a handle from proximal to distal to stabilize the patella. Two double-loaded all-suture anchors are placed on the medial side of the proximal patella, separated by about 1 cm to form an adequate bone bridge.

Each limb is then passed over the suture anchor with 2 high-tension sutures, one of each color exiting superior and one of each color exiting inferior to the overlying graft. The graft is then held out, and the patella is placed into the appropriate zone for tracking, with roughly 1 quadrant of lateral translation from midline as the appropriate laxity. We mark with a marking pen where the graft is passing the anchor at this tension. A free needle is used to pass both of the sutures from 1 side, 1 of each color, through the graft, in a locking configuration. The sliding side of each suture is then pulled to shuttle the sutured graft down and then tied to the same color. This is repeated for the second suture and then replicated for the inferior graft limb. The MPFL is now reconstructed.

Roughly 1 cm lateral to the medial border of the patella, the retinacular tissue on top of the patella is sharply incised from proximal to distal, creating a retinacular bridge under which to pass the limbs of the MPFL autograft as well as the native MPFL retinacular flap. Next, we work on the MPFL repair and VMO advancement. The 2 limbs of the MPFL, as well as the retinacular flap, are pulled underneath the retinacular window created anterior to the patella. No. 2 Ethibond sutures are then used to begin to close the vertical retinacular incision overlying the patella, and sutures are utilized to capture and reef together the MPFL and medial retinacular flap in a figure-of-8 fashion.

Next, the VMO advancement is performed. The VMO fascia is advanced more inferiorly along the medial border of the patella, and No. 2 Ethibond is used in a figure-of-8 fashion to tie the confluence of the MPFL graft and the retinaculum to the leading edge of the VMO fascia, thereby completing this advancement.

Finally, the arthroscope is inserted into the knee via the superior medial portal and taken through a range of motion 0° to 90° over the side of the bed. Here we show the improved tracking of the patella.

Our full postoperative protocol is copied here, but in brief, patients are allowed partial weightbearing with crutches with the brace locked in extension. Nonweightbearing flexion is limited to 0° to 50° and advanced 10°/wk to 0° to 90° by 1 month.

From months 1 to 3, patients progress toward full weightbearing and focus on gait training. The brace is weaned off. From months 3 to 7, patients work toward quad strengthening with closed-chain exercises, jogging, and then functional recovery.

Results and Discussion

For a brief outcome review with regard to TTO and MPFL, this comparative study looked at 3 groups of MPFL reconstruction alone, MPFL reconstruction with medializing TTO, and MPFL reconstruction with medializing and distalizing TTO. ² Medialization was performed for TT-TG >20 and distalization for the Caton-Deschamps Index (CDI) >1.4. They found that for these common indications, combined medial and distal realignment does well for patients when appropriately indicated for elevated CDI and TT-TG. ²

Regarding the addition of TTO, multiple studies have compared MPFL reconstruction with TTO versus MPFL reconstruction alone. This Level II study looked at prospective cohorts with patients who had a “gray” zone TT-TG of 17 to 20 mm. ¹ They found that there were better improvements in the combined group without recurrent instability in either group. There was better function and knee kinematics with the combined group. Their take-home point was that with a higher TT-TG, combined MPFL reconstruction, and TTO was superior to MPFL alone. ¹

Regarding complication rates, our group has looked at early complications after MPFL reconstruction and TTO, and there is a low risk of major complications, even with distalization.^4,5 In a mid-term follow-up, we did find a higher 7% risk of major complications with a 12% progression of tibiofemoral osteoarthritis but an overall very low re-dislocation rate. ³

Results

At 7 months postoperatively, follow-up images of 2-view left knee radiographs showed a healed TTO and improved patellar height. These follow-up videos show full painless motion without extensor lag and stable patellar tracking. Thank you for your time.