Medial Patellofemoral Ligament Reconstruction With a Single-Limb Allograft: A Reproducible and Effective Technique

Abstract

Background:

Medial patellofemoral ligament (MPFL) injury occurs in up 96% of lateral patellar dislocations, commonly affecting those less than 20 years old. The MPFL can be reconstructed using either a double-limb or single-limb technique. While both techniques achieve similar patient outcomes, a single-limb technique may require less operative time.

Indications:

The MPFL reconstruction is indicated in patients with recurrent patellar subluxations, dislocations, or unresolved apprehension. Care should be exercised in identifying whether patients require additional procedures in addition to MPFL reconstruction such as tibial tubercle osteotomy or trochleoplasty. These considerations include TT-TG >17 to 20 mm and Dejour B/D trochlear dysplasia.

Technique Description:

Following diagnostic arthroscopy, a medial peripatellar incision is made. Layers 1 and 2 are sharply dissected over the patellar periosteum, and tissue planes are subsequently developed using Metzenbaum scissors. A plane between layers 2 and 3 extending from the medial patella to the medial femoral epicondyle is developed. Using fluoroscopy, Schöttle point is identified, and a femoral tunnel is drilled. Two PEEK anchors are placed at the junction of the proximal one-third and distal two-thirds of the patella. In parallel, a tibialis anterior graft is sized, whipstitched, and tensioned on the back table. One end of the prepared graft is secured in the femoral tunnel with a PEEK tenodesis screw. The graft is then shuttled between layers 2 and 3, followed by fixation on the patellar side using the previously placed suture anchors. Isometry of the graft is confirmed under direct and arthroscopic visualization.

Results:

In multiple systematic reviews of single-limb versus double-limb MPFL reconstruction, no differences were observed in terms of patient-reported outcome scores, repeat dislocation, and reoperation. Furthermore, a recent meta-analysis suggests a trend toward less postoperative stiffness (1.2% vs 3.5%, P = .09) for single-bundle techniques.

Discussion/Conclusion:

Single-limb MPFL reconstruction is reproducible and effective, with clinically satisfactory outcomes and low failure rates. Single-limb MPFL reconstruction demonstrates similar outcomes as double-limb reconstruction, with a potential decrease in surgical time and postoperative stiffness.

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

The following is a video on medial patellofemoral ligament (MPFL) reconstruction with a single-limb allograft, providing a reproducible and effective technique.

We have no relevant disclosures.

In this presentation, we will discuss the background of MPFL injury, go over a brief patient case presentation, describe our preferred surgical technique, discuss tips and tricks, postoperative management, and conclude with published patient outcomes.

The MPFL injury is common and occurs in up to 96% of lateral patellar dislocations. ³ In particular, this injury often occurs in young and active patients, less than 20 years of age. The MPFL reconstruction recreates the native medial restraint of the patella and has been described using 2 main techniques: single limb and double limb.^1,5

We believe that a single-limb reconstruction technique can be advantageous as it provides similar outcomes but may require less operating room time.

Our patient case revolves around a 23-year-old woman with chronic right patellar instability. She had an index, noncontact dislocation 10 years ago, which was followed by greater than 5 subsequent repeat instability events. She has trialed nonsteroidal anti-inflammatory medications, physical therapy, and bracing but continues to rate her pain at a 5 out of 10 and have apprehension. She rates herself at 25% to 30% of normal function.

In terms of physical examination, her range of motion (ROM) is 0° to 80°, and is limited by apprehension. She has 2 quadrants of medial and 3+ quadrants of lateral patellar translation with no firm endpoint. She has a positive J-sign, no retropatellar crepitus, and 5/5 quadriceps and hamstring strength. Her knee is otherwise stable.

Plain anteroposterior, lateral, and sunrise view radiographs demonstrate no fracture or osteoarthritis. Imaging is notable for a Caton-Deschamps index of 1.2 and no trochlear dysplasia.

Magnetic resonance imaging demonstrates a torn and attenuated MPFL and lateral patellar subluxation. There is no evident loose osteochondral fragment and her TT-TG is measured to be 16 mm.

In terms of surgical decision-making, we believe indications for MPFL reconstruction include recurrent patellar subluxations, dislocations, or unresolved apprehension. The need for reconstruction of the MPFL is highlighted by the fact that it is torn in greater than 95% of primary dislocation events.

Additional considerations include tibial tubercle osteotomy for patients with TT-TGs greater than 17 to 20 mm, trochleoplasty for Dejour B or D dysplasia with a bump height ≥ 9 mm, and patellofemoral arthroplasty for bipolar chondral defects and post traumatic isolated patellofemoral osteoarthritis.

The patient is positioned supine and prepped and draped in standard surgical fashion. Diagnostic arthroscopy demonstrates a laterally subluxed patella and otherwise well-preserved chondral surfaces and intact menisci and ligaments.

Our attention is then turned to open MPFL reconstruction. We make a 2.5-cm incision at the junction of the proximal one-third and distal two-thirds of the medial border of the patella. We then dissect skin and subcutaneous tissues and establish medial and lateral soft tissue flaps.

Subsequently, we identify the superomedial patella and, directly over the patella, sharply incise layers 1 and 2 over the patellar periosteum. By sharply incising through these layers, we can then readily appreciate each tissue plane and dissect between layers 1 and 2 as well as 2 and 3 using Metzenbaum scissors. To better highlight the utility of this facile approach, we have provided a broader exposed dissection on a cadaveric specimen. All layers are sharply incised over the superomedial patella. Subsequently, the space between layers 1 and 2 and the space between layers 2 and 3 can be readily developed. In this dissection image, we again highlight the ready distinction between layers 1 and 2, and the native anatomic relationship of the MPFL on the undersurface of layer 2.

Using a curved clamp, we tunnel down to the medial epicondyle to Schöttle point. We find that it can be helpful here to tag layers 1 and 2 with a suture so that this can be readily retracted at the time of future graft passage.

We then make a 2-cm incision just posterior to the medial epicondyle and, with a lateral C-arm view, we advanced a guide pin at Schöttle point, docking it in but not through the lateral cortex and drill a 7-mm tunnel to the depth of 20 mm.

On the patellar side, at the junction of the proximal one-third and distal two-thirds of the medial patella, we place two 2.4-mm PEEK anchors (SutureTak, Arthrex, Naples, Florida) loaded with #2 ultra-high-molecular-weight polyethylene suture, approximately 8 mm apart.

In parallel with exposure, on the back table, we prepare the tibialis anterior allograft construct. We ensure the tibialis anterior allograft can be passed through a 6-mm graft sizer and both ends of the graft are whipstitched with #2 ultra-high-molecular-weight polyethylene suture. The graft is placed on 15 lbs of tension for 15 minutes.

Following satisfactory graft preparation, we implant the allograft first on the femoral side. We load one end of the whipstitched suture into a 6.25 mm × 15 mm PEEK tenodesis screw and in such a way, are able to insert the graft and provide interference fixation with the screw without having to pass a pin in a bicortical fashion and without having to pull a pin through the lateral soft tissues. Stable purchase is achieved.

We then shuttle the graft between layers 2 and 3, using a curved clamp passed from our patellar incision, under the previously tagged layers, and pulling on the tag stitches on the other end of the graft.

On the patellar side, we drape the graft over the previously placed patellar anchors in 30° of knee flexion and neutral rotation. This is marked on the graft with a marker. Gentle ROM under direct visualization is used to confirmed isometry of the graft. With the knee in 30° of flexion and neutral rotation, the graft is then fixated to the superomedial border of the patella, passing the 4 suture limbs from the 2 anchors through the allograft and tying them as 2 mattress knots. Excess graft is then trimmed distal to the mattress knots. We then close layers 1 and 2 over the graft and gently imbricate using a 0 Vicryl suture.

Arthroscopic visualization confirms that the patella is now centered in the trochlear groove, without over constraint medially.

The wound is then copiously irrigated, and the subcutaneous layers are closed with 2-0 Vicryl and the skin with 3-0 Monocryl. Steri-Strips were applied as well as a dry sterile dressing. A hinged knee brace was placed locked in extension.

In terms of tips and tricks, we recommend that surgeons incise directly over the superomedial patella, bringing the incision down to periosteum, as this allows for facile separation of the anatomic layers. We also use fluoroscopy and anatomic landmarks for femoral tunnel positioning. Proximal drilling may limit flexion, whereas distal tunnels may limit extension. We also recommend drilling distal to the physis in skeletally immature individuals.

Prior to graft passage, one should ensure that the plane between layers 2 and 3 is clear of any adhesions as tissue bridges may lead to catching and graft anisometry. Finally, surgeons should ensure appropriate graft tension after fixation, using a trial of full ROM under direct and arthroscopic visualization.

For postoperative rehabilitation, patients may weight bear as tolerated immediately with crutches and a brace locked in extension. The brace is unlocked at 2 weeks and physical therapy is begun. At 6 weeks, the brace is discontinued, jogging is begun at 12 weeks, and consideration for return to sport is begun at 24 weeks pending full pain-free ROM, no apprehension, and return of symmetric quadriceps strength.

In terms of published outcomes, Kang et al ² compared 254 single-limb and 819 double-limb reconstructions. No significant differences were observed in postoperative Kujala score. Single-limb patients had a higher rate of apprehension, but double-limb patients trended toward an almost 3-fold increased risk of postoperative stiffness.

Migliorini et al ⁴ compared 899 single-limb and 1035 double-limb reconstructions with similar age and time to surgery. There were no differences in complications, reoperations, or re-dislocations noted, and there was a trend toward decreased apprehension in the single-bundle cohort.

In conclusion, single-limb MPFL reconstruction is effective and reproducible, demonstrating satisfactory outcomes and low failure rates. Compared with double-limb reconstruction, similar outcomes, reoperation, and repeat dislocation rates can be expected. However, a single-limb technique does provide potentially less surgical time and postoperative stiffness.

The following are our references.

Thank you for your time and attention.