Simultaneous Reconstruction of Medial Patellofemoral and Medial Patellotibial Ligaments

Abstract

Background:

Medial patellofemoral ligament (MPFL) reconstruction (MPFLR) is the gold standard for treatment of recurrent patellofemoral dislocation; the medial patellotibial ligament (MPTL) may be added in certain patients.

Indications:

Habitual patellar dislocation in flexion; recurrent patellar dislocation associated with knee hyperextension; mild patella alta; low-grade trochlear dysplasia; patients with open physis who have contraindication for bony procedures; apprehension in deep flexion; and recurrent patellar dislocators without obvious risk factors but marked apprehension.

Technique Description:

MPFLR and MPTLR using a single peroneal tendon allograft. The patellar fixation includes a tunnel and one anchor, the tibia one anchor, while the femur does not use implants but a sling around the adductor magnus tendon.

Results:

This is a safe procedure with a preliminary low rate of complications and good functional results.

Discussion/Conclusion:

We recommend MPFLR plus MPTLR with a single graft to add extra stability. It is a surgical technique that can be used in both children and adults, but is particularly useful in patients with open physes.

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 video demonstrates a technique for reconstructing the medial patellofemoral ligament (MPFL) and the medial patellotibial ligament (MPTL) using a peroneal tendon allograft. The procedure involves creating a tunnel and placing an anchor in the patella, utilizing a sling around the adductor magnus tendon in the femur, and fixing with an anchor in the proximal tibia. This investigation was conducted at the Fundación Valle del Lili Hospital in Cali, Colombia. The authors report no conflicts of interest. The video content includes the rationale for treating recurrent patellar dislocation, indications for MPFL reconstruction (MPFLR) and MPTL reconstruction (MPTLR), a case presentation with demonstration of the technique, the rehabilitation protocol, tips and tricks, and conclusions.

Background

The MPFL is the primary restraint against lateral patellar translation, while the MPTL is a secondary restraint. ⁵ Although the MPFL primarily functions between 0° and 30° of knee flexion, the MPTL becomes increasingly crucial during deeper flexion, serving as the main stabilizer from 60° to 90° for patellar shift, tilt, and rotation. It is also useful in terminal extension, as it directly counteracts quadriceps contraction.^6,12 The MPTL inserts in the medial edge of the distal patella and in the proximal anteromedial tibia. The reconstruction of the MPFL is considered the gold standard for the surgical treatment of recurrent patellofemoral dislocation. However, patients may require additional interventions, including bony procedures. In cases of patella alta, distalization of the tibial tuberosity may be necessary. For increased tibial tuberosity-trochlear groove (TT-TG) distance, medialization of the tibial tuberosity is indicated; trochleoplasty is recommended for high-grade trochlear dysplasia; lateral lengthening may be performed if there is lateral tightness; and derotation may be required for torsional issues in the femur or tibia.^9,11

Indications

While the use of the adductor tendon as a sling for femoral fixation of the MPFL has been described in previous studies,^3,10 this paper presents a technique that utilizes the same allograft to reconstruct the MPTL. This additional procedure may be indicated in specific circumstances, such as habitual flexion dislocation, knee hyperextension, medial laxity or apprehension in deeper knee flexion, mild patella alta, low-grade trochlear dysplasia, and pediatric patients where bony procedures cannot be offered.

This case involves a 19-year-old male patient with recurrent patellar dislocation in his left knee. The examination revealed medial laxity of 2.5 quadrants, a positive apprehension test between 0° and 45°, no lateral tightness, and no J sign. There were no clinical signs of torsional issues in the femur or tibia. Imaging studies demonstrated no trochlear dysplasia, no alterations in the TT-TG distance, and mild patella alta with an Insall-Salvati index of 1.27.

Technique Description

Surgery is performed with the patient in a supine position. Lateral and medial laxity are assessed under anesthesia. Anatomical landmarks, such as the adductor tubercle, patella, joint line, and patellar tendon, are identified. The peroneus longus allograft is prepared on an accessory table, mixed with saline solution and vancomycin. We recommend a graft of at least 20 cm in length. First, an arthroscopy is conducted through conventional portals, primarily to evaluate the articular cartilage. Then, it continues as an open surgery. The goal is to achieve a double-bundle MPFLR using a socket tunnel and an anchor in the patella, a sling beneath the adductor magnus tendon for the femur, and an anchor for the proximal tibia.

A medial approach should be utilized to access the upper and medial thirds of the medial border of the patella. In the upper third, a guide pin is inserted from the medial to the lateral side of the patella, followed by the creation of a tunnel using a 4.5-mm cannulated drill to a depth of 10 to 15 mm. A Prolene 1 suture is then placed here to later pass the first bundle of the graft into the tunnel. Next, a 2.8-mm titanium FASTak suture anchor is placed in the middle third of the medial patella to fix the second bundle of the MPFL, which also serves as the patellar attachment for the MPTL, as it is the same graft that subsequently extends to the tibia. The tibial insertion point for the MPTL is selected 1 cm below the joint line and at an angle of 15° to 30° divergent from the patellar tendon; a 2.8-mm titanium FASTak suture anchor is positioned at this site.

A 2-3 cm incision is made on the medial side of the knee at the site of the adductor tubercle, where the insertion of the adductor magnus tendon is located. Next, the second layer of the medial retinaculum is identified at the patellar incision. A Rochester clamp can be utilized to create a tunnel through the second layer, connecting the patella to the adductor magnus tendon. The adductor tendon should be clearly identified, as it will be used to form a loop with the allograft around it. Two Prolene 1 sutures will be employed to pass the graft toward the adductor tendon and back to the patella. The graft is then pulled into the patellar tunnel to reconstruct the first bundle of the MPFL. This bundle is sutured to the periosteum at the entrance of the tunnel. The graft is passed through the tunnel, around the adductor tendon, and back to the patella. The first bundle is fixed at 40° of flexion with a Vicryl 1 suture to the adductor tendon. The lateral displacement of the patella is assessed after fixing each bundle, ensuring that it remains with 0.5 to 1 quadrant of movement, to prevent increased pressure on the medial patellofemoral joint. Next, the second bundle is sutured to the patellar anchor at 30° of knee flexion. Finally, the remaining free allograft is utilized to reconstruct the MPTL. It is passed through layer 2 using a Rochester clamp and sutured to the tibial anchor while the knee is flexed at 90°. The final stability of the patella is assessed, and the wounds are closed.

Potential complications include compromising the articular cartilage of the patella with the anchor or the tunnel, as well as in the proximal tibia with the anchor. To prevent this, it is recommended to use fluoroscopy to assess the position of the anchors and the guide pin. Fluoroscopy is always necessary to position the tibial anchor in open physis patients. To identify the adductor tendon more easily, first, localize the medial epicondyle, which is the most prominent of the medial bony structures; then, identify the adductor tubercle, which is slightly posterior and proximal. The adductor magnus tendon is the structure that inserts into this tubercle.

Results

In the postoperative treatment, patients do not require a knee brace. Immediate partial weightbearing is permitted to achieve full weightbearing by 4 weeks after surgery. Isometric strengthening exercises begin on the first day, and the range of motion aims for 0° to 90° during the first 2 weeks, progressing to a full range of movement in the next 2 to 4 weeks. Return to sports is a progressive process that depends on individual goals. Typically, it includes indoor cycling at 6 weeks, jogging or running at 10 weeks, sport-specific exercises at 12 weeks, and a return to sports practice between 4 and 6 months.

Discussion/Conclusion

A combination of MPFLR and MPTLR has shown good functional results and a low rate of complications. ¹⁴ A case-series found less patellar apprehension and less subluxation in extension with MPFLR plus MPTLR compared with isolated MPFLR. ⁷ Techniques using the adductor tendon as a sling have also shown good biomechanical results in basic studies, and have been safe and effective in clinical studies.^1,2,3,4,8,13 This paper presents a novel way of reconstructing both ligaments in recurrent patellar dislocation, especially useful in open physis scenarios.