Lateral Patellofemoral Ligament Reconstruction With Semitendinosus Allograft for Chronic Medial Patellar Subluxation

Abstract

Background:

The lateral patellofemoral ligament (LPFL) is a key stabilizing structure that prevents medial patellar subluxation. LPFL insufficiency may result from iatrogenic injury, particularly after lateral retinacular release in patients with patellofemoral pain and maltracking. Various surgical techniques have been described for LPFL reconstruction (LPFLR), with soft tissue fixation allowing greater medial translation compared with osseous fixation. This study outlines an LPFLR, performed in a looped fashion, using a semitendinosus allograft for the treatment of chronic medial patellar subluxation.

Indications:

Surgical reconstruction is indicated in patients with chronic medial patellar subluxation due to LPFL insufficiency and is commonly secondary to prior lateral retinacular release, particularly in cases refractory to conservative management. A semitendinosus allograft is utilized for its durability, availability, and ability to restore patellar stability while minimizing donor site morbidity.

Technique Description:

The procedure involves harvesting a semitendinosus allograft, securing its midpoint at the femoral LPFL attachment, and reconstructing the LPFL in a loop passage. Longitudinal incisions are made in the patellar retinaculum, through which the graft is passed deep from the lateral to medial window and then passed laterally in the superficial tissue, creating a loop graft configuration. The graft is tensioned appropriately and fixed using a high-tensile nonabsorbable suture to reestablish lateral constraint while allowing controlled patellar mobility. The construct is designed to optimize biomechanics and reduce the risk of recurrent instability.

Results:

At 2 weeks postoperatively, the patient reports reduced pain and improved knee stability. She continues to attend physical therapy twice weekly, achieving 68° of knee flexion with a slight tight sensation. Full recovery is anticipated within 6 to 12 months, provided continued rehabilitation is maintained, as is typically expected with the LPFL recovery protocol.

Discussion/Conclusion:

This study presents the surgical management of chronic medial patellar subluxation in a 36-year-old woman via an LPFLR with a semitendinosus allograft. The optimal LPFLR technique remains unclear, necessitating further research to establish best practices and long-term outcomes in the management of patellar instability. However, this looped technique has shown beneficial results in procedural outcomes and improved stability with range of motion.

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 our technique for lateral patellofemoral ligament reconstruction using a semitendinosus allograft for the treatment of chronic medial patellar subluxation.

Background

The lateral patellofemoral ligament (LPFL) is a palpable thickening of the joint capsule between the lateral patella and epicondyle.^4,6,10 It serves an important role in preventing medial patellar subluxation, which may commonly present as a result of iatrogenic injury after lateral retinacular release in the setting of patellofemoral pain and maltracking. ⁸ Surgery is recommended only when LPFL insufficiency is seen, and all other common patellofemoral disorders are ruled out via comprehensive evaluation. Multiple techniques are described for LPFL reconstruction (LPFLR), with soft tissue fixation allowing greater medial translation than osseous fixation, which provides insight into the optimal treatment for restoring stability.^2,8 Additionally, a range of allografts have been described.^1,2,5 Ultimately, the optimal LPFLR technique has not been determined.

Indications

Case

In this case, LPFLR was performed using a semitendinosus allograft, which was restructured using knotless femoral fixation and all soft tissue patellar fixation in a looped configuration.

The patient is a 36-year-old woman who presented to our clinic with a chief complaint of left knee pain for >20 years. She describes her pain as constant and severe, associated with significant swelling with prolonged standing or sitting, leading to a limp in her gait and occasional near falls. Additionally, she reports a sharp pain in the center of her kneecap as well as a grinding sensation during squats. She has had multiple previous surgeries on her left knee, including plica band removal, meniscal debridement and repair, as well as lysis of adhesions and arthroscopic lateral release. Her last knee arthroscopy was performed in 2018 without any subsequent injuries.

Preoperative planning included physical examination of the left knee in the office. The patient demonstrated a full range of motion of the knee, both passive and active, with a positive patellofemoral grind test, a subtle reverse J sign, and apprehension with medial translation. The patient otherwise had full strength and a stable ligamentous examination, with no additional positive provocative tests.

Preoperative Imaging and Positioning

Radiographic imaging of the knee demonstrated preserved joint space. The magnetic resonance imaging scan showed a mild effusion, as well as low-grade patellar chondrosis with a subtle medial patellar tilt. For this procedure, the patient was placed in the supine position with a lateral post and a "speedbump" to allow for both extended and 90° flexed positioning of the knee.

The intraoperative examination shows excessive patellar translation and medial subluxation with manipulation. Arthroscopic evaluation demonstrated grade 2 or 3 patellar chondromalacia as well as scarred/patulous lateral capsule consistent with previous arthroscopic release.

Technique Description

Exposure of the Lateral Patellofemoral Origin

The open procedure begins with an incision made approximately 1 cm distal and 1 cm proximal to the inferior and superior poles of the patella, respectively. Dissection is carried down to the iliotibial (IT) band. The layer superficial to the lateral capsule and deep to the IT band is described as layer 2 and is home to the native LPFL. The lateral epicondyle is used to localize the femoral LPFL insertion, which lies approximately 13 mm anterior and distal to this landmark. A FiberTak knotless all-suture anchor (Arthrex) is subsequently placed at the femoral LPFL attachment. Next, 2 sets of parallel, longitudinal incisions of approximately 1.5 cm length are made.

Patellar Tunneling

The medial incisions follow the native LPFL insertion at the lateral patellar border, and the lateral incisions are made in line just 1.5 cm lateral. The goal is to create 2 layers, 1 deep and 1 superficial to the IT band, for graft passage—1 deep and 1 superficial to the patellar retinaculum. Hemostats are inserted to define the layers and facilitate the passage of the graft. A semitendinosus allograft of approximately 25 cm length is prepared in sterile fashion at the back table by whipstitching both ends with a No. 2 Fiber loop suture (Arthrex). The midpoint of the graft is marked and secured using the knotless FiberTak anchor previously placed at the femoral LPFL insertion.

Allograft Passage

Next, the distal and proximal limbs of the graft are each passed up through the lateral soft tissue windows, staying deep to the IT band. The graft is then shuttled from the lateral window, up and out the medial window, in the lower layer, deep to the patellar retinaculum.

Before the final graft passage step, an attempt is made to imbricate the patulous capsule and retinaculum using No. 1 Vicryl suture (Ethicon). The graft is now passed back laterally, down through the medial and out the lateral window, in the superficial layer, creating a sling around the retinaculum. Tension of the construct is assessed through the full active range of motion of the knee.

Construct Design

The cadaveric dissection illustrates the native LPFL, which is located deep to the IT band and reflected laterally. The anatomic depiction, adapted from Kerzner et al, ⁵ highlights the soft tissue windows for this technique. All incisions are made through the IT band, with the initial graft passage being deep to it. However, our method positions the graft superficially when doubled medially to laterally. Additionally, our technique incorporates the distal quadriceps and proximal patellar tendons. This literature confirms that soft tissue graft reconstruction restores stability in a greater range of flexion than osseous fixation in the setting of a lateral retinacular release.

Assessment and Securing of the Allograft

The graft tension is examined to ensure that 2 quadrants of translation are achieved medially and laterally. With the desired tension achieved, the graft tails are trimmed and reinforced with a high-tensile, nonabsorbable suture, with the knee fully extended. The arthroscope is subsequently reintroduced to assess patellar tracking from proximomedial and distal-lateral portals. Final images are taken arthroscopically, which demonstrate the visible limbs of the graft superficial to the capsule without undue tension. Lastly, the wounds are closed in layers with nonabsorbable suture, and the skin is closed with Monocryl in standard fashion.

Results

After this procedure, the patient was placed in a hinged knee brace for immobilization. From weeks 0 to 6, the patient was allowed weightbearing as tolerated with a hinged knee brace locked in extension. Full motion is permitted when the patient is not bearing weight, with minimum increases of 15° per week. Progressive strengthening begins at 6 weeks, with a goal of return to sport by 4 months. Between 3 and 6 months, goals include achieving full knee range of motion and engaging in pain-free activities of daily living. Patients are encouraged to continue with physical therapy until a full return to sport.

At 2 weeks postoperatively, the patient reports reduced pain and improved knee stability, with no complications— including incision site infection, fever, or deep vein thrombosis. Full recovery is anticipated within 6 to 12 months, with continued rehabilitation.

Discussion/Conclusion

This technique has an unknown overall complication rate but may include issues such as misidentification of the LPFL femoral attachment site, infection, neurological complaints, graft over-tensioning, or graft failure.^2,7 However, patient-reported outcomes show significantly decreased knee pain, improved function, and higher Knee injury and Osteoarthritis Outcome Scores.^1,3,5 Functionally, the procedure enhances medial stability, and patient satisfaction is high, with studies reporting 100% effectiveness in treating medial apprehension.^1,9 Overall, LPFLR with a soft tissue graft should be considered in cases of instability after lateral retinacular release. Further studies should compare graft reinforcement paths with patient functional scores.

For optimal LPFLR, first, identify the lateral epicondyle to ensure precise femoral insertion. When passing the graft, position it deep to the IT band in layer 2 laterally and transition superficially in layer 1 medially for proper anatomical alignment. Enhance patellar fixation by incorporating the lateral proximal patellar and distal quadriceps tendons. Before final fixation, confirm proper graft tension to prevent instability, and address any capsular or retinacular defects to reinforce stability and reduce the risk of recurrence.