Abstract
Background:
Patellofemoral instability is a common condition that is associated with significant long-term morbidity.
Indications:
Persistent patellofemoral instability following a trial of nonoperative management.
Technique Description:
Combined medial patellofemoral ligament and medial quadriceps tendon femoral ligament (MPFL/MQTFL) reconstruction with double-bundle semitendinosus allograft.
Results:
In a consecutive series of 142 patients with a minimum 2-year follow-up, failure rate was 7.7%. Patients had improved functional outcomes, as compared to those who underwent nonoperative management.
Discussion/Conclusion:
MPFL/MQTFL reconstruction is an operative solution to patellofemoral instability, which yields decreased rates of re-dislocation and improved patient functional outcomes. This technique also has the capacity to restore native anatomy and prevent the development of osteoarthritis over time.
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.
This is a visual representation of the abstract.
Keywords
Video Transcript
This technique describes a medial patellofemoral ligament and medial quadriceps tendon femoral ligament (MPFL/MQTFL) using a double-bundle semitendinosus allograft.
The authors have nothing to disclose.
In this video, we will discuss the background of patellofemoral instability, review the surgical indications for a combined MPFL/MQTFL reconstruction, walk through the technique, and finally discuss the outcomes and clinical significance of this approach to patellofemoral instability.
Background
Patellofemoral Instability
Patellofemoral instability is a continuum of pathology, ranging from partial subluxation to frank dislocation of the patella in relation to the trochlea.
Epidemiology
This condition is relatively common, with an estimated incidence of 42 per 100,000 person-years. 1 It is associated with significant morbidity, including anterior knee pain and a high rate of recurrent instability following initial dislocation.3,4
Presentation
History
Patellofemoral instability most commonly affects pediatric and adolescent patients and is associated with risk factors such as prior instability, anatomic susceptibility—includingpatella alta and trochlear dysplasia—with a potential contribution from ligamentous laxity. It often results from noncontact rotational or pivoting injuries, although it may also occur during contact sports, particularly in adolescent and adult patients. Patients typically report symptoms of subjective instability, anterior knee pain, and/or episodes of frank dislocation.
Clinical Significance
Recurrent instability and maltracking can, over time, lead to progressive structural damage and an increased risk of developing patellofemoral osteoarthritis. 2 This is a particularly important consideration in younger patient populations.
Evaluation
History and Exam
Evaluation begins with a thorough history and physical examination. This includes documenting current patient symptoms, such as anterior knee pain, the patient’s personal history of instability or dislocation events, and assessing whether or not mechanical symptoms are present. A standard bilateral knee examination is then performed, with particular attention to patellar translation and apprehension.
Imaging
Radiographs are essential for evaluation of patient anatomy and to rule out fractures or loose bodies. Magnetic resonance imaging can confirm MPFL injury and characterize osteochondral lesions.
Nonoperative Management
An initial trial of nonoperative management should be attempted in this patient population, consisting of physical therapy with an emphasis on quadriceps strengthening, patellofemoral bracing, and activity modification, guided by symptoms and pain.
Surgical Management
Indications
Surgical intervention is indicated for recurrent patellofemoral instability, for patients initially presenting with an associated osteochondral injury, and for those who have unsuccessful nonoperative management after a first-time dislocation, as MPFL/MQTFL reconstruction has been shown to yield superior functional outcomes, as compared to nonoperative management in this cohort. 6
Contraindications
MPFL/MQTFL reconstruction is contraindicated in patients who are not medical candidates for surgery. Multiple techniques for the management of patellar instability have been described, including MPFL reconstruction, MQTFL reconstruction, and combined MPFL/MQTFL reconstruction. Alternative procedures, such as medial plication, lateral release, trochleoplasty, and tibial osteotomy, have also been extensively described, although they have lost favor in recent years.
The heterogeneity in management options reflects the complex anatomic balance of the patellofemoral joint and argues that there may not be a “one-size-fits-all” solution to patellofemoral instability. Ultimately, a patient’s particular anatomy and risk factors for patellofemoral instability should be considered when planning operative intervention. 8
With regard to reconstruction of the ligament itself, biomechanical studies have shown double-bundled MPFL reconstruction to potentially contribute to overconstraint of the patella, with the inclusion of an MQTFL limb offering a more anatomic repair. 1
Preoperative Planning
Risks and Benefits
A comprehensive discussion of the risks and benefits of surgery should be performed with the patient and family. This discussion should address operative risks, such as infection, deep vein thrombosis, damage to surrounding structures, and arthrofibrosis. The goals of surgery are to restore stability and decrease the subsequent chance of redislocation, use the MPFL/MQTFL construct to restore native anatomy, and improve patient functional outcomes.
Imaging Review
Before surgery, physicians should review relevant patient imaging, with particular attention to the potential need for additional procedures, and for that patient’s specific anatomy.
Technique Description
Let’s take a closer look at the specific steps of the procedure.
Patient Positioning
Patients are positioned supine. Following induction, a regional adductor canal block is performed. A tourniquet can then be inflated on the operative thigh, per surgeon preference.
Diagnostic Arthroscopy
Complete diagnostic arthroscopy is then performed through standard anteromedial and anterolateral portals. At this time, consideration and execution of any additional required procedures, such as lateral release, loose body removal, or cartilage restoration, are made.
Allograft Preparation
The semitendinosus allograft is then prepared at a back table with a graft preparation system of the surgeon’s choosing.
Patellar Anchor Placement
The procedure begins with the patellar anchor placement at the medial patellar border. With the knee in 30° to 40° of flexion, a 3-cm longitudinal incision is made at the medial border of the patella. A 1.8-mm suture anchor is then placed at the junction of the proximal and central third of the patella. This will later serve as the attachment site for the graft’s patellar limb.
MPFL/MQTFL Femoral Attachment
Next, we move to the femoral attachment. With the knee in extension, a 2-cm longitudinal incision is made at the level of the medial epicondyle. The Schöttle point is then identified through palpation and fluoroscopy. A K-wire can be placed to confirm positional accuracy. Isometry is then performed prior to K-wire removal and bioabsorbable polyether ether ketone anchor placement.
Here we see a knee in which the medial incision has been made, a Schöttle point has been identified, and a K-wire has been placed, with its position confirmed with fluoroscopy. A snap can be placed on the K-wire to aid in this fluoroscopic confirmation. The anchor is then placed.
The graft’s midpoint is then identified and marked. The graft is placed through the free anchor loop and then tightened and secured. Sutures are placed through both limbs, securing the graft to the adjacent periosteum.
Here we see the midpoint being identified and marked, the excess graft being excised, and the graft being placed through the suture loop. The loop is then tightened and tied down. Security is tested. Both limbs of the graft are then secured to the surrounding periosteum.
MPFL Patellar Attachment
Attention is then turned to the patellar origin, where the MPFL limb will be attached. Both graft limbs are initially retrieved through the patellar incision. With the knee in 30° to 40° of flexion, the patella is centralized to the trochlea. The distal graft limb is then tensioned and secured to the previously placed suture anchor. The knee is ranged under gross and arthroscopic evaluation to confirm alignment, tensioning, isometry, tracking, and centralization.
Demonstrated here is the retrieval of both graft limbs through the patellar incision. The patella centralization is manually performed, with distal graft limb tensioning and securing. Tracking and isometry are confirmed as the knee is ranged. This evaluation is performed both with and without arthroscopy.
MQTFL Reconstruction
Finally, the MQTFL reconstruction is performed, attaching the proximal graft limb to the vastus medialis oblique (VMO) at the level of the proximal patella.
With the knee in 30° to 40° of flexion, this point is initially identified through the patellar incision. The allograft limb is then tensioned, and suture fixation is used to secure the limb. Arthroscopy is again used to confirm proper tensioning, normal tilt, and normal tracking of the patella.
Here we can see the MQTFL limb being tensioned and secured to the VMO.
Both limbs are now secured, and final alignment is confirmed with arthroscopy before excess graft removal.
Closure
Attention is then turned to closure. Excess fluid is removed, and the incisions are closed with 2-0 Vicryl (Ethicon) and 3-0 Monocryl (Ethicon) in a buried interrupted fashion. Steri-strips, a sterile dressing, and an Ace wrap are applied. The patient is then placed in a hinged knee brace for postoperative use.
Postoperative Examination
Restoration of proper alignment and patellar stability is demonstrated here and should be confirmed postoperatively.
Postoperative Protocol
Postoperative management includes twice-weekly physical therapy with an emphasis on quadriceps strengthening. Weightbearing progresses from touch-down weightbearing during the first 2 weeks with a gradual increase of 25% per week thereafter. Range of motion is initially limited to 30° or 60°, depending on cartilage damage. This is increased 30° every 2 weeks thereafter.
Results
Return to impact training typically begins at 12 weeks, with progression to pivoting and twisting between 16 and 20 weeks. Return to sport can occur as early as 4.5 months, depending on strength recovery.
Complications
Potential complications, as discussed preoperatively, include infection, deep vein thrombosis, structural damage, and arthrofibrosis.
Patient Outcomes
Literature
There is significant heterogeneity in the literature due to the wide range of currently used techniques for MPFL reconstruction. Small cohorts describing similar MPFL/MQTFL operative techniques have resulted in favorable patient-reported functional outcomes postoperatively. Namely, Spang et al 7 have described a cohort of 19 knees, with strong functional outcome scores and a 77% return-to-sport rate at 2 years after intervention. 6
Failure
Outcomes associated with this procedure have been described in our consecutive cohort of 142 patients with a minimum 2-year follow-up. Among this group, we observed a failure rate of 7.7%, defined as subsequent redislocation of the patella. This was significantly less than the failure rate assessed for patients undergoing nonoperative management. 5
Functional outcomes
This cohort also demonstrated superior functional outcome scores compared to patients who were managed nonoperatively, as measured by the Kujala and Pediatric International Knee Documentation Committee scores. They also had a higher return-to-sport rate, at 88%. 5
Discussion/Conclusion
This technique provides a reliable operative solution for patellofemoral instability, particularly in the pediatric and adolescent populations. By restoring native anatomy and improving functional outcomes, this approach can significantly reduce the long-term morbidity associated with recurrent dislocation, including the development of osteoarthritis.
Thank you for your time and attention.
Footnotes
The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
