Proximal Patellar Realignment: Medial Patellofemoral Ligament Reconstruction & Retinacular Plication Masterclass

Welcome, fellows, to the operating theater. Today, we're addressing a challenging yet rewarding pathology: patellofemoral instability. This condition, often presenting as pain and dysfunction in children and young adults, can significantly impact quality of life. It’s crucial to understand that instability, rather than mere pain, is the primary indication for the procedures we'll perform today: a medial retinacular plication and, if warranted, a medial patellofemoral ligament (MPFL) reconstruction.

Patellofemoral instability manifests across a spectrum, from subtle subluxation to frank dislocation. While some individuals may exhibit generalized ligamentous laxity, others, particularly athletes, experience instability due to acute traumatic events or underlying anatomical predispositions. A deficient lateral femoral slope of the trochlear groove, for instance, significantly reduces the inherent bony constraint, lowering the force required for lateral patellar translation or dislocation.

The Natural History and Rationale for Intervention

Injuries to the medial aspect of the patellofemoral joint frequently involve disruption of the MPFL, often accompanied by stretching or tearing of the medial retinaculum. This can lead to persistent pain and, more importantly, recurrent instability. Patients with an atraumatic onset of instability tend to have a higher likelihood of repeat episodes, even despite aggressive non-operative measures.

Our key to surgical intervention is the persistent complaint of instability, corroborated by examination findings consistent with patellar instability, with or without pain. It is imperative, fellows, that we avoid realignment surgery solely for pain. While a traumatic event may cause a fracture or loose body, necessitating surgical removal, the primary goal of realignment is to restore stability.

The debate surrounding acute surgical intervention for first-time dislocators, especially young athletes without generalized ligamentous laxity, remains active. However, for those with recurrent instability despite diligent non-operative management, or those with significant bony pathology like large, displaced avulsion fractures or loose bodies, surgical stabilization is clearly indicated.

Comprehensive Surgical Anatomy of the Patellofemoral Joint

Before we make our incision, let's meticulously review the anatomy. A thorough understanding is paramount to safe and effective surgery.

Osteology and Articular Surfaces

The patellofemoral joint comprises the patella, a sesamoid bone embedded within the quadriceps tendon, and the trochlear groove of the distal femur.
* Patella: Its posterior surface features medial and lateral articular facets, which articulate with the femoral trochlea. The size and congruence of these facets are critical for smooth tracking.
* Femoral Trochlea: This V-shaped groove guides the patella. Its morphology is key to stability. A shallow trochlea, or one with a hypoplastic lateral condyle, significantly predisposes to lateral instability (trochlear dysplasia, often classified by Dejour). The medial epicondyle is a crucial landmark, serving as the femoral attachment site for the native MPFL. The adductor tubercle, just superior to the medial epicondyle, is a common anatomical reference for MPFL reconstruction, though the true isometric point is slightly more distal and anterior.
* Tibial Tuberosity: The insertion point of the patellar tendon. Its position relative to the trochlear groove (measured as the Tibial Tubercle-Trochlear Groove, or TT-TG distance) is a critical factor in patellar tracking. Excessive lateralization increases the lateral pull on the patella.

Ligamentous and Retinacular Structures

The primary medial restraints of the patellofemoral joint are the medial retinaculum and, most crucially, the medial patellofemoral ligament (MPFL).
* Medial Patellofemoral Ligament (MPFL): This ligament provides 40% to 60% of the resistance to lateral patellar translation. It is approximately 15 mm wide and originates from the medial aspect of the patella, typically 10 to 15 mm distal to the superior pole, near its widest portion. It courses obliquely to insert into the medial epicondylar area of the femur, just proximal and anterior to the origin of the superficial medial collateral ligament (MCL). It is intimately associated with the vastus medialis obliquus (VMO) insertion.
* Medial Retinaculum: A broader fascial layer reinforcing the medial capsule, blending with the VMO and MPFL. It contributes to overall medial stability.
* Vastus Medialis Obliquus (VMO): The most distal and oblique fibers of the vastus medialis, inserting into the superomedial aspect of the patella. It acts as a dynamic medial stabilizer. Its insertion is typically distal to the superior pole of the patella and anterior to the medial intermuscular septum.
* Lateral Retinaculum: Composed of transverse and oblique fibers, often taut in instability, contributing to lateral patellar tilt and excessive lateral translation. It blends with the iliotibial band.

Neurovascular Risks

During our medial approach, we must be acutely aware of vital structures:
* Saphenous Nerve: The infrapatellar branch of the saphenous nerve crosses the operative field, particularly during medial parapatellar incision and subcutaneous dissection. It typically courses obliquely across the medial aspect of the knee. Careful, layered dissection and the use of subcutaneous flaps can help protect it, minimizing the risk of postoperative numbness or neuroma formation.
* Medial Superior Genicular Artery: This vessel can be encountered during deeper dissection, especially when identifying the femoral attachment site for the MPFL. Meticulous hemostasis is essential.

Preoperative Planning: The Blueprint for Success

Effective preoperative planning is the cornerstone of a successful outcome. We meticulously review every piece of information to tailor our approach.

Patient History and Physical Findings

A thorough history will reveal the mechanism of injury (traumatic vs. atraumatic), frequency of instability episodes, and impact on daily activities.
* Associated Injuries: Always consider the differential diagnosis, including meniscal tears (joint-line tenderness, painful popping with provocative maneuvers like McMurray or Apley compression tests, potential loss of extension), medial collateral ligament (MCL) tears, chondral injuries or bruises, anterior cruciate ligament (ACL) tears, tendinitis, and even conditions like Osgood-Schlatter or Sinding-Larsen-Johansson disease in younger patients.
* Effusion: Presence and size of joint effusion.
* Patellar Stability Testing: This is critical. With the knee in 30 degrees of flexion (relaxing the patellar tendon), we assess medial and lateral translation.
* Increased laxity (25% to 50% of patellar width): Suggests increased laxity but a still-competent retinaculum and MPFL.
* Insufficiency (>50% of patellar width): Indicates significant compromise of both the MPFL and medial retinaculum, making reconstruction more likely.
* Lateral Retinaculum Tightness: Assessed by medial patellar translation. Less than 12 mm of medial translation suggests a tight lateral retinaculum, which may warrant a concomitant lateral release.
* Bony Anatomy and Alignment:
* Quadriceps Angle (Q-angle): Measure this angle, as a greater-than-average Q-angle increases the lateral translational force on the patella.
* Femoral Rotation: Average is external rotation greater than or equal to internal motion. Excessive femoral anteversion can contribute to patellar maltracking.
* Tibial Alignment: Average axis is 10 to 15 degrees of external tibial torsion.
* "Miserable Malalignment Syndrome": This describes a constellation of malalignments, including excessive femoral anteversion with or without increased external tibial torsion, which cumulatively contribute to patellofemoral instability.
* Dynamic Observation: Observe and palpate the patella for lateral subluxation, the "J sign," during active range of motion. This is a visible lateral shift of the patella as the knee extends from flexion, resembling the shape of a "J."

Imaging and Other Diagnostic Studies

• Radiographs: Standard anteroposterior (AP), lateral, and Merchant (sunrise) views are essential. We evaluate for fractures, loose fragments, patellar height (Insall-Salvati or Caton-Deschamps index), and trochlear morphology.
• Magnetic Resonance Imaging (MRI): Provides detailed information on soft tissue injuries (MPFL tears, meniscal pathology, chondral lesions), bone bruising (often seen on the lateral femoral condyle and medial patella after dislocation), and loose bodies.
• Computed Tomography (CT) Scan: Crucial for assessing axial alignment, femoral and tibial rotation, and, most importantly, the TT-TG distance. An elevated TT-TG (typically >20mm) indicates excessive lateralization of the tibial tubercle, which might necessitate a tibial tubercle osteotomy in addition to soft tissue procedures.

Nonoperative Management Considerations

While we're here for surgery, remember that over 80% of patients respond well to nonoperative treatment initially. This typically includes:
* RICE (Rest, Ice, Compression, Elevation) and NSAIDs.
* Immobilization: For approximately 6 weeks following an acute dislocation.
* Physical Therapy: Immediate initiation to strengthen the quadriceps (especially VMO), hip flexors, and abductors (which are routinely weak in this patient population). A patellar protection program is key.
* Bracing: A lateral patellar restraint type of brace for return to activity.

Nonoperative treatment is particularly appropriate for multiple dislocators or subluxators with generalized ligamentous laxity or an atraumatic presentation. However, for recurrent dislocators who fail therapy, dislocate in a brace during activities, or have significant loose bodies/fractures, surgical intervention is the next logical step.

Preoperative Setup and Patient Positioning

Alright team, let's get our patient ready.

1. Pre-Positioning Examination Under Anesthesia (EUA): Before positioning and prepping, we'll perform a comprehensive EUA. This is paramount. We'll assess ligamentous stability (Lachman, pivot shift, varus-valgus stress, anterior-posterior drawer) and, critically, medial and lateral patellar stability at 45 degrees of knee flexion. Compare these findings to the opposite, unaffected knee. Remember, translation of the patella over 50% of its width laterally confirms incompetency of both the MPFL and medial retinaculum, necessitating both structures to be addressed during surgery.

2. Patient Positioning:

   • The patient is placed in the supine position on the operating table.
   • The operative leg is kept free, allowing full range of motion throughout the procedure.
   • A tourniquet is applied to the proximal thigh of the operative leg.
   • The foot of the table is flexed about 30 to 45 degrees to optimize visualization of the medial compartment and allow for tensioning of the medial structures.
   • A lateral post is used just proximal to the knee to create a valgus moment, further opening the medial compartment.
   • The opposite leg can be positioned per surgeon's preference—either flexed 90 degrees in a well-padded stirrup or kept flat on the table with appropriate padding.
   • Fluoroscopy Setup: The C-arm will be positioned to allow for easy acquisition of AP, lateral, and Merchant (sunrise) views to confirm patellar tracking and hardware placement, especially if a femoral tunnel is used for MPFL reconstruction.

3. Sterile Prep and Drape: A standard sterile prep and drape of the entire lower extremity, from the iliac crest to the foot, ensuring the knee can be moved freely. The tourniquet is then inflated to 300 mmHg.

Step-by-Step Intraoperative Execution: The Surgeon's View

Alright, fellows, scalpel in hand. Let’s begin.

I. Initial Incision and Dissection: Medial Retinacular Plication Approach

"We'll start with a generous medial parapatellar incision. I'm making it curvilinear, centered over the widest portion of the patella, extending proximally about 3-4 cm above the superior pole and distally about 3-4 cm below the inferior pole. This provides ample exposure for both the retinacular plication and potential MPFL reconstruction."

"Now, using electrocautery, we meticulously dissect the subcutaneous tissues. We're elevating subcutaneous flaps both anteriorly and posteriorly. This is crucial, fellows, for two reasons: first, it allows for excellent mobility of the prepatellar skin, minimizing the length of our external incision. Second, and perhaps more importantly, it helps protect the infrapatellar branch of the saphenous nerve, which often courses superficially in this area. We want to keep our dissection superficial to the retinaculum until we are ready to open it."

"Once our flaps are developed, we expose the underlying quadriceps tendon, the VMO, the medial retinaculum, and the patella itself. We can clearly see the fibers of the VMO inserting into the superomedial aspect of the patella."

"Next, we make our incision into the tendon and retinaculum. I'm making this incision from approximately 3 to 4 cm above the superior pole of the patella, extending distally to 3 to 4 cm distal to the inferior pole. Critically, we are making this incision medial to the tendon, leaving about 2 mm of tendon with the VMO. This ensures we have a robust edge on the VMO side for our imbrication sutures. We incise the entire depth of the retinaculum and tendon down to the joint capsule."

Here, you can see the initial medial parapatellar incision, with subcutaneous flaps being developed to expose the underlying retinaculum and VMO.

Note how the medial parapatellar incision is made, leaving a 2-3 mm cuff of quadriceps tendon attached to the vastus medialis obliquus for later imbrication.

II. Medial Retinacular Plication (Modified Insall Technique)

"Now, we'll proceed with the medial retinacular plication. Assistant, please hold the knee in 45 degrees of flexion. This is our critical angle for tensioning. I'm also asking you to gently hold the patella in a reduced position, centered within the trochlear groove. This allows us to assess the amount of laxity we need to correct and set our baseline tension."

"We'll use three nonabsorbable sutures, typically No. 1 or No. 2, placed in a horizontal mattress fashion. I'm placing these sutures to imbricate the edge of the VMO tendon and the retinaculum distally and laterally. Each suture is placed approximately 25% to 40% across the width of the patella from medial to lateral. We're essentially taking a bite of the more lateral, deeper retinaculum and plicating it underneath the more medial, superficial VMO-retinacular flap. We want to gather and tighten that medial laxity."

"I'm placing these sutures now, but we're not tying them yet. This allows us to dynamically assess our tension. Assistant, please hold these sutures taut. Now, I'll take the knee through a full range of motion, from full extension to 90 degrees of flexion. I'm carefully observing the patellar tracking. We want to ensure that with the sutures held tight, the patella tracks smoothly without excessive medial translation or overtightening. We're looking for stable tracking without a 'C-sign' (patella catching on the medial trochlea) or excessive resistance to flexion. If there's still too much lateral laxity, we can adjust our suture placement or take a larger bite."

"Satisfied with the tracking and tension, we'll now tie these three nonabsorbable sutures. Tie them securely, but avoid excessive tension that could lead to patella baja or restricted range of motion. Once these are tied, we'll use a 0 absorbable suture to reinforce the tension set by these primary sutures, placing it above and below the imbrication. This helps distribute the load and provides additional strength."

"Finally, I'll run a continuous, locking 0 absorbable suture over the entire imbrication line. This not only further reinforces our plication but also helps to lower its profile, reducing the risk of palpable knots or irritation postoperatively."

III. Medial Patellofemoral Ligament Reconstruction (If Indicated)

"In this patient, based on our preoperative imaging and EUA, the MPFL is frankly incompetent, and a plication alone would be insufficient. Therefore, we will proceed with an MPFL reconstruction using a quadriceps tendon autograft. This is often the case when the lateral patellar translation exceeds 50% of the patellar width on EUA."

"First, let's prepare our graft. I'm taking the medial 6 to 8 mm of full-thickness quadriceps tendon as a 50 to 60 mm long graft. Crucially, it remains attached to the superior pole of the patella. This preserves the blood supply and allows for a strong anchor point."

Here, we are harvesting the medial quadriceps tendon graft, ensuring it remains attached to the superior pole of the patella at its widest portion. Note the length needed for reconstruction.

"Now, I'll subperiosteally reflect the graft distally about 10 to 12 mm from the superior pole of the patella. I'm being careful to reflect slightly more distally on the lateral aspect of the graft's patellar attachment. This subtle maneuver allows the graft to fold over on itself more naturally during fixation and tensioning, preventing kinking."

"Once the graft is harvested, I'll place a nonabsorbable suture, typically a No. 1 or No. 2, in the free end of the graft using a whipstitch or Krakow stitch technique. This provides a strong, secure handle for passing and tensioning the graft."

"Next, we need to prepare the recipient site. We'll dissect the retinaculum from the subcutaneous tissue superficially, working our way back towards the medial intermuscular septum. Simultaneously, we dissect the retinaculum from the synovium deep

Additional Intraoperative Imaging & Surgical Steps

REFERENCES

1. Insall JN. Disorders of the patella. In Insall JN, ed. Surgery of the knee. New York: Churchill Livingstone, 1984:191.

2. Insall JN, Bullough PG, Burstein AH. Proximal “tube” realignment of the patella for chondromalacia patellae. Clin Orthop Relat Res 1979; 144:63–69.

3. Mountney J, Senavongse W, Amis AA, et al. Tensile strength of the medial patellofemoral ligament before and after repair or reconstruction. J Bone Joint Surg Br 2005;87B:36–40.

4. Noyes FR, Albright JC. Reconstruction of the medial patellofemoral ligament with autologous quadriceps tendon. Arthroscopy 2006;22: 904.e1–7.

5. Late fixation failure is uncommon but can happen if flexion beyond 90 degrees is started too soon postoperatively.

6. Arthrofibrosis should be treated aggressively with manipulation under anesthesia if greater than 90 degrees of flexion is not obtained by 6 weeks.

7. Continued pain may occur, especially if not enough or too aggressive of a lateral release was performed, leading to either increased pressure on the patella or medial pressure and instability.