Abstract
Many techniques have been described for the reconstruction of the medial patellofemoral ligament (MPFL) in patients with acute or recurrent instability. Most commonly, an MPFL hamstring tendon auto- or allograft is used, attached to the patella and medial femoral condyle using bone tunnels and various fixation implants to ensure stable fixation and graft healing. We describe a surgical technique in which an MPFL semitendinosus graft is inserted in a partial-width transverse patellar bone tunnel (typically 6-6.5 mm in diameter and 15-20 mm in length) and stabilized using adjustable loop cortical button fixation. In the femur, a tunnel is drilled in an oblique superolateral direction (typically 6-6.5 mm in diameter and 30 mm in length), and the graft is inserted and stabilized using an absorbable interference screw. The graft is tightened at 60° of knee flexion and retensioned after knee cycling as necessary, with the adjustable loop button. The described technique affords sufficient initial graft fixation strength, thereby eliminating the need for postoperative immobilization.
Technique Video
The medial patellofemoral ligament (MPFL) is a checkrein, opposing lateral patella subluxation or dislocation during the first 20° of knee flexion.1, 2, 3 It is the main passive stabilizer of the patellofemoral joint, has a mean tensile strength of 208 N, and can resist 12 to 18 mm of elongation before failure.1 Patellar dislocation is accompanied by a tear or plastic deformation of the MPFL, leading to lateral patellar subluxation, delayed trochlea engagement, and an increased risk of new dislocation.2
MPFL reconstruction is a universally accepted surgical technique for restoring patellofemoral stability in patients with acute or chronic patellar dislocation. Numerous techniques have been reported using various graft types and fixation methods, with or without implants, all attempting to restore normal MPFL anatomy at both the femoral and patellar insertion sites.
MPFL reconstruction using a fixed-loop cortical button has been previously described with good results and a low complication rate.3,4 The looped graft can be stabilized with a cortical button in the patella5,6 or femur.7, 8, 9, 10
We describe a surgical MPFL reconstruction technique using a partial-width transverse patellar tunnel in which the tendon graft is inserted and stabilized using an adjustable-loop cortical suspension button. An oblique tunnel is created at the femoral insertion site, and graft fixation is accomplished using an interference screw.11 Strong MPFL graft fixation allows early mobilization and potentially faster recovery after surgery.
Surgical Technique
The surgical technique is shown in Video 1 and Fig 1, Fig 2, Fig 3, Fig 4, Fig 5, Fig 6, Fig 7, Fig 8, Fig 9, Fig 10, Fig 11, Fig 12, Fig 13, Fig 14, Fig 15, Fig 16.
Fig 1.
The patient is placed in the supine position on the operating table. A tourniquet is placed in the proximal thigh, and the right knee is positioned at 90° of flexion using a proximal lateral support at the level of the greater trochanter. A second support is used to stabilize the foot.
Fig 2.
Positioning of the C-arm fluoroscopy device to provide anteroposterior (A) and lateral knee projections (B) is crucial for the success of the procedure.
Fig 3.
Hamstring tendons are harvested using a standard anteromedial or posteromedial skin incision. In the posteromedial technique for the right knee, the semitendinosus is exposed (A), all fascial attachments are released, and the tendon is harvested (B) using a tendon stripper.
Fig 4.
With the right knee in extension, a 3- to 5-cm long medial parapatellar skin incision was made along the superomedial border of the patella to expose the medial patellar surface.
Fig 5.
Using a tunnel-aiming device (A) or most commonly with a free-hand technique (B), under fluoroscopic guidance, a 2.5-mm guide pin is inserted at the center of the anatomic footprint of the medial patellofemoral ligament in the patella, at its proximal third, exiting the lateral patellar border (C) in the right knee.
Fig 6.
The 2.5-mm guide pin is inserted at the center of the anatomic footprint of the medial patellofemoral ligament in the patella (A) in the right knee. A cannulated reamer is used to drill a partial-width patellar socket (B). Star, patella
Fig 7.
Fluoroscopic verification of patellar bone socket drilling in the right knee. A tunnel guide can be used (A), although the freehand technique is the most common method (B). A guide pin is inserted, and a 4.5-mm canulated reamer is used to create a tunnel for the passage of the cortical suspension button (C). Finally, a 6- to 7-mm canulated reamer creates a 15- to 20-mm long patellar bone socket that accommodates the tendon graft (D).
Fig 8.
A looped free suture was passed through the patella, exiting at the lateral patellar surface (A, B) in the right knee, and was used to shuttle the graft into the patellar socket. A soft-tissue tunnel is then created between layers II and II, connecting the patella to the medial patellofemoral ligament anatomic insertion site posterior and proximal to the medial femoral epicondyle (C).
Fig 9.
The adjustable-loop cortical suspension button (A, arrow) was shuttled through the patella (B) in the right knee and finally inserted into the patellar bone socket (C).
Fig 10.
With the right knee in 90° of flexion, the anatomic insertion site of the medial patellofemoral ligament is located using fluoroscopy in the true lateral projection. A guide pin assists in localizing the correct insertion point in the medial femoral condyle.
Fig 11.
In the right knee, a 2.5-mm guide pin is inserted in the proximal-lateral direction (A, B) and a 6- to 7-mm canulated reamer is used to create the femoral tunnel, which will accommodate the free ends of the tendon graft.
Fig 12.
Fluoroscopic verification of guide pin insertion (A, B) and drilling of the femoral tunnel (C).
Fig 13.
A suture loop (A) is used to shuttle the tendon graft into the femoral tunnel (B) in the right knee.
Fig 14.
The tendon graft is inserted into the femoral tunnel (A), and an interference screw is used to stabilize the graft (B) in the right knee.
Fig 15.
Fluoroscopic image of MPFL reconstruction in the right knee. Anteroposterior (A) and lateral (B) knee projections.
Fig 16.
Fluoroscopic image of inadequate cortical button flipping (arrow) in the right knee. Soft-tissue interposition is observed between the button (arrow) and lateral patellar border (dashed line). This complication can be avoided by using fluoroscopic verification.
Anesthesia and Patient Positioning
Surgery is performed after the induction of general or regional anesthesia, with the patient positioned supine on the operative table and the operative lower limb prepped and draped. Vancomycin antibiotic prophylaxis is administered 1 hour before the skin incision, and a second-generation cephalosporin is administered at the time of anesthesia induction. A tourniquet is placed at the proximal thigh, and the knee is positioned at 90° flexion. The lower limb is stabilized with a proximal lateral support at the level of the greater trochanter, and a second support is used to stabilize the foot (Fig 1). A fluoroscopy device is used to facilitate knee imaging in the anteroposterior and lateral projections (Fig 2). Bilateral evaluation of patellar mobility is performed via manual examination, translating the patella in the medial and lateral directions to evaluate the degree of patellar instability. In patients with secondary intra-articular injuries, knee arthroscopy is performed before MPFL reconstruction to assess the extent of intra-articular cartilage lesions and guide the subsequent steps of reconstruction. The condition of the patellar and femoral cartilage is evaluated, loose bodies are removed, and treatment of the cartilage injury is performed. The MPFL reconstruction technique uses transverse patellar and oblique femoral tunnels to secure the semitendinosus tendon graft, with the primary goal of recreating the anatomy of the native MPFL.
Hamstring Graft Harvesting and Preparation
A tendon graft, typically the gracilis or preferably the semitendinosus autograft, is harvested, or an allograft is prepared. A semitendinosus autograft is preferred over the commonly used gracilis autograft for MPFL reconstruction because it is a more robust and longer tendon. The semitendinosus autograft is harvested using a longitudinal or transverse incision or a posteromedial 3- to 4-cm-long skin incision centered over the pes anserinus (Fig 3). An endoscopic-assisted graft harvesting technique may be used to minimize graft harvesting morbidity,12 and the graft is harvested using a closed tendon stripper to avoid graft amputation. Occasionally, if the harvested graft is insufficient, both hamstring tendons can be harvested and used for reconstruction. The tendon graft is prepared by tapering its ends, whip-stitching them with No. 2 nonabsorbable sutures, and passing them through the loops of an adjustable-loop cortical button (ULTRABUTTON [Smith & Nephew] or ProCinch [Stryker]). Graft trimming is usually unnecessary. The graft is sized to determine its diameter and then wrapped in vancomycin-soaked gauze until ready for implantation. After careful hemostasis, the wound is closed in layers and infiltrated with 10 mL of ropivacaine.
Patellar Exposure and Tunnel Creation
The patellar bone tunnel is created first, and the graft is secured using an adjustable-loop cortical button. The borders of the patella and medial femoral condyle are marked on the skin. With the knee in extension, a 3- to 5-cm long medial parapatellar skin incision is made along the superomedial border of the patella, starting at the proximal pole of the patella (Fig 4). The superficial and deep retinaculum (layers I and II) are sharply incised, and the proximal one third of the medial patellar border is exposed. The retinaculum is sharply peeled off the patella to expose the patellar footprint of the MPFL. The vastus medialis obliquus (VMO) muscle typically inserts on the proximal third of the patella, and the MPFL runs parallel to it and inserts along the superomedial corner of the patella. Cutting through the muscle fibers of the VMO should be avoided to prevent muscle atrophy. The underlying knee joint capsule (layer III) can be easily identified and preserved, although we prefer to expose the patellar articular surface and measure the anteroposterior diameter of the patella using a ruler. A transverse patellar tunnel is created in the mediolateral direction at the midpoint of the anteroposterior diameter to avoid creating a shallow, anteriorly located patellar tunnel. Accurate anteroposterior positioning of the patellar tunnel is essential because anterior tunnel placement places the patella at risk of fracture, whereas posterior patellar tunnel placement may violate the patellar cartilage. The entry point for the patellar tunnel is located between the equator and proximal pole of the patella.
A trough is created on the medial patellar border using a curette or rasp, producing a bleeding surface to facilitate the healing of the knee capsule and tendon graft. Using an anterior cruciate ligament knee guide or a freehand technique, a 2.5-mm guide pin is driven transversely through the patella, exiting at its lateral surface (Fig 5). The exact location and orientation of the pin are verified using fluoroscopy. A cannulated 4.5-mm reamer is then passed over the guide pin to create a transverse patellar tunnel sufficient for the passage of the cortical button (Fig 6). Occasionally, the patellar bone is hard, and counterpressure from the lateral patellar surface is necessary for drilling. An appropriately sized reamer, usually 6 to 6.5 mm, corresponding to the diameter of the tendon graft, is used to drill a 15- to 20-mm-long socket in the patella. Drilling across the patella should be avoided to prevent accidental fractures.
A looped free suture is passed through the patellar tunnel, exiting at the lateral patellar surface, and used to shuttle the graft into the patellar socket (Fig 7). The adjustable-button sutures are passed through the loop and pulled through the patella, exiting at the lateral patellar cortex. The button is flipped by pulling the flipping suture (which is used for controlled flipping of the cortical button) while applying countertension (Fig 8). After flipping, the graft is pulled medially to assess the adequacy of the flip (Fig 9). Fluoroscopy is used to confirm that the button is properly seated on the lateral patellar cortex without soft-tissue interposition. The tendon graft is marked according to the socket length, which is usually 20 mm, and is pulled into the socket until it reaches the medial patellar surface. The adjustable loop is then tensioned.
Femoral Tunnel Creation
The femoral attachment of the MPFL typically is located between the adductor tubercle and medial epicondyle. In patients who are thinner, but not in those who are muscular or who have obesity, the medial epicondyle and adductor tubercle are palpable.
The location of the Schottle femoral fixation point is determined using intraoperative fluoroscopic imaging in all patients. A perfect lateral knee fluoroscopic view is essential to identify the Schottle point on the medial femoral condyle, which is slightly proximal and posterior to the medial epicondyle between the medial epicondyle and adductor tubercle, distal to the latter. The correct insertion point is identified on fluoroscopy with the knee at 90° flexion (Fig 10, Fig 11, Fig 12). A 2- to 3-cm-long skin incision is made between the medial epicondyle and the adductor tubercle, posterior to the VMO muscle fibers. If muscle fibers are encountered, an anterior incision is made. The periosteum is elevated to expose the medial femoral bones. A Beath pin is inserted at the anatomical MPFL location aiming proximal and anterior to avoid the intercondylar notch and overdrilled with a 6-mm cannulated reamer, corresponding to the size of the graft, for 3 to 3.5 cm, avoiding penetration of the anterior femoral cortex. A suture loop is inserted into the eyelet of the Beath pin and pulled to the proximal lateral femoral surface to facilitate graft insertion into the femoral socket. A nitinol wire is placed into the femoral tunnel parallel to the Beath pin to facilitate interference screw insertion.
Graft Passage and Fixation
The tendon graft is passed from the patellar to the medial femoral condyle wound using a curved Kelly clamp inserted between layers II and III, thereby creating a soft-tissue tunnel. The clamp is passed deep to the retinaculum but extra-articularly, exiting at the femoral wound, creating a tunnel wide enough to accommodate the tendon graft. Another Kelly clamp is passed through the soft-tissue tunnel and exits at the patellar wound. The sutures with which the 2 tendon graft limbs are whip-stitched are withdrawn into the femoral wound and finally exit at the medial femoral wound. Alternatively, a suture loop or similar suture-pulling device can be used to deliver the graft limb sutures through the medial femoral incision.
The graft sutures are loaded into the eyelet of the femoral Beath pin, which is pulled proximally, delivering the sutures to the lateral femoral side (Fig 13). The sutures are pulled, and both graft limbs are inserted into the femoral socket. It is important to remove all soft tissue from the femoral tunnel opening to avoid graft passage obstruction.
The knee is cycled 20 times from full extension to full flexion, placing mild tension on the graft by pulling the sutures exiting laterally. The knee is then placed in 60° of flexion, ensuring that the patella is centered in the trochlea under direct vision through medial patellar exposure. A 7- to 8- × 25-mm bioabsorbable screw (BIOSURE REGENESORB; Smith & Nephew) was then inserted in the femoral tunnel over the nitinol wire, without tapping, whereas the patella is stabilized between the thumb and index finger of the surgeon to avoid patellar medialization (Fig 14). In rare cases, when either the femoral bone is very hard or the tendon graft is very stiff, the femoral socket is tapped. Screw protrusion is verified and corrected using digital palpation. The screwdriver and nitinol wire are removed, and the soft tissues are sutured around graft. Fluoroscopic verification of the implant and patellar position is performed to ensure satisfactory implant placement (Figs 15 and 16).
Range of Motion Testing and Wound Closure
The knee is cycled through a range of motion to assess graft tension and patellar tracking. The knee joint is moved from full extension to full flexion throughout the knee range of motion, ensuring satisfactory patellar tracking. If patellar maltracking or over tensioning or undertensioning is noticed, the femoral screw is temporarily removed, appropriate actions and adjustments are made, and the screw is reinserted. Alternatively, with the described technique, graft retensioning is possible by taking advantage of the properties of adjustable loop cortical button fixation. In our experience, this is necessary in most cases.
The knee joint capsule is repaired using absorbable sutures, and the patellar retinaculum is repaired using nonabsorbable sutures, incorporating the tendon graft into the repair using horizontal mattress sutures. Imbricating the medial patella retinaculum in a pants-over-vest fashion is often warranted, and advancement of the VMO is also possible.
Postoperative Rehabilitation
No knee brace or other forms of immobilization are applied to the knee. Full weight-bearing is allowed postoperatively as tolerated by the patient. Knee flexion is limited to 60° for the first 3 weeks, and full range of motion is achieved between the sixth and eighth weeks postoperatively. A carefully planned rehabilitation program is essential for regaining range of motion, strength, and proprioception. Return to everyday activities is allowed 6 weeks postoperatively and return to sports 4 to 6 months after the operation.
Discussion
A successful MPFL reconstruction technique warrants anatomical accuracy in the placement of the femoral and patellar fixation points and proper graft tension to ensure stability and prevent re-dislocation. A structured rehabilitation program is critical for successful outcomes and return to activities.
Several options are available for MPFL graft fixation in the patella and femur, with or without implants. MPFL reconstruction using implants is associated with a greater rate of patellar fractures, whereas implant-free techniques are associated with a greater risk of subluxation.4,13 There is no significant difference between anatomic and nonanatomic MPFL reconstruction techniques in terms of patient-reported outcomes and complications. Thus, the choice of surgical technique may be left to the surgeon’s preference.13
In the described technique, adjustable button fixation is used on the patella to stabilize the hamstring tendon graft. The major advantage of using an adjustable button is the ability to retension the graft after knee cycling. In anterior cruciate ligament reconstruction, adjustable button fixation offers several potential benefits, including increased graft incorporation, a potentially reduced risk of graft displacement, and the ability to dynamically retension the graft.14 Adjustable buttons allow for dynamic stabilization of the knee and can accommodate different tunnel lengths, potentially leading to a more secure and stable reconstruction.15 Possible complications associated with the use of suture buttons include button misplacement, late intra-articular migration, skin irritation, and increased graft-tunnel motion under load, potentially causing tunnel widening.
Skin irritation from the presence of a subcutaneous metallic button in MPFL reconstruction may occasionally occur and warrant removal.5 Another key concern is the possibility of loosening of the adjustable loop under cyclic loading compared with the fixed-loop device, which can lead to graft laxity and potentially failure of the reconstruction.16
Careful consideration of the biomechanical properties and potential complications is crucial when choosing between adjustable and fixed-loop fixation methods. Ensuring proper button position and graft tensioning can be technically challenging. Adjustable buttons allow dynamic graft tensioning, which may better replicate the natural movement of the patellofemoral joint and potentially improve functional outcomes.
Both hamstring tendons can be harvested and used for MPFL reconstruction in cases with a small semitendinosus tendon. The graft is tensioned at 60° of knee flexion because the patellar contact pressures are negligible medially and lower laterally, as well as the patellar translation and patellar tilt.3
The success of MFPL reconstruction is inherently bound to the precise location of the anatomic MPFL insertion site in the patella and medial femoral condyle. Correct patellar and femoral tunnel placement is critical for the success of the operation. Femoral tunnel malpositioning results in increased contact pressure, patellar translation, tilt, and graft tightening or loosening.3 The femoral tunnel should be positioned at the anatomic MPFL attachment area between the medial femoral epicondyle and the adductor tubercle. Correct femoral tunnel placement nearly restores native patellofemoral contact pressures and isometry.3,17
Fixed-loop cortical button fixation has been described for the patella5,6 and femur.7, 8, 9, 10 Sim et al.10 performed anatomic double-bundle MPFL reconstruction in a series of 11 patients using an ipsilateral semitendinosus tendon autograft. The free tendon ends were fixed to the patella, and the graft loop was inserted into the femoral tunnel and fixed using an adjustable-length loop device. After a minimum of 2 years of follow-up, no cases of dislocation recurrence were observed. Mohammed et al.5 retrospectively compared single tunnel patella fixation with a button with a double-tunnel technique using anchors, reporting more dislocation with the former technique and more knee pain with the latter technique.
A core feature of the currently described technique is that prolonged immobilization after surgery is not required, which is common in MPFL reconstruction methods. Full weight-bearing without the need for postoperative knee immobilization potentially leads to faster functional recovery and return to activity. By avoiding immobilization, this technique may reduce muscle atrophy, decrease the incidence of postoperative stiffness, and potentially shorten the overall recovery time. Although promising, further research is needed to confirm long-term outcomes and compare this technique with established MPFL reconstruction methods. Pearls and pitfalls of the technique are described in Table 1; advantages and disadvantages are listed in Table 2.
Table 1.
Pearls and Pitfalls of the Medial Patellofemoral Ligament Reconstruction (MPFL) Technique Using Adjustable Loop Cortical Fixation Button in the Patella
| Pearls |
| Additional procedures, such as cartilage repair, lateral retinacular release, and tibial tubercle osteotomy, are performed before MPFL reconstruction. |
| The patella is stabilized by the surgeon’s hand to facilitate tunnel drilling in the occasionally hard patellar bone. |
| In adults, the diameter of the patella and the femoral sockets are usually 6-7 mm |
| Reduction of the patella before definitive fixation can be accomplished under direct vision through the medial knee arthrotomy |
| Fluoroscopic verification of the tunnel location and implant positioning is crucial. |
| The graft isometry of the MPFL can be assessed intraoperatively. |
| In patients with obesity and in revision cases, both hamstring tendons can be used for improved graft strength |
| Adjustable-loop cortical suspension buttons are more versatile in cases with varying patellar tunnel lengths, potentially eliminating the need for multiple loop sizes. |
| After the graft is secured, the knee is fully extended and flexed to ensure that full passive motion is unhindered. |
| After knee cycling, graft retensioning is possible with an adjustable loop button. |
| Pitfalls |
| The correct positioning of the adjustable-loop cortical suspension button should be confirmed with fluoroscopy to prevent complications, such as flipping of the button or becoming trapped in soft tissue during insertion, which could lead to complications, such as skin irritation or tension loss. |
| The position of the nitinol wire in the femoral tunnel should be verified using fluoroscopy to avoid complications during interference screw insertion. |
| Avoid drilling full patellar length transverse tunnels larger than 6 mm or multiple tunnels across the patella. |
| The entrance of the femoral socket should be cleared of all soft tissues to facilitate graft insertion. |
| There should be little or no tension in the graft when the patella is centered in the trochlear groove, regardless of the angle of knee flexion. |
| Fluoroscopy, isometry, or both are used to double-check the femoral attachment point. Anisometric graft placement can lead to overtensioned or undertensioned grafts and eventually failure of the operation. |
| It is very important to avoid overtensioning, that is, medializing the patella. |
Table 2.
Advantages and Disadvantages of the Medial Patellofemoral Ligament Reconstruction (MPFL) Technique Using Adjustable-Loop Cortical Suspension Fixation Button on the Patella
| Advantages |
| The use of an adjustable-loop cortical fixation button provides a strong and reliable cortical fixation, which is superior to interference screws. |
| The adjustable loop button provides intraoperative adjustability, allowing graft tension fine-tuning during the procedure and compensating for variations in tunnel length, ensuring optimal graft fixation. |
| Graft-to-bone contact in the patella is maximized, potentially improving graft incorporation and healing. |
| The adjustable-loop cortical button provides dynamic tensioning of the graft, which may better replicate the natural movement of the knee joint and potentially improve functional outcomes. |
| Retensioning the graft is possible after final fixation and knee cycling. |
| It can be used with all graft types. |
| Suture anchors and transosseous sutures can be used to provide additional fixation to the greater tuberosity. |
| This technique is relatively easy to learn, familiar to knee surgeons, and associated with a rapid increase in proficiency. |
| The gracilis tendon is preserved, except in cases where the semitendinosus graft is insufficient or amputated during harvesting. |
| Adjustable loops can minimize the "bungee cord effect" by allowing tension adjustment, potentially leading to a more stable reconstruction. |
| It can be used in primary and revision cases. |
| Disadvantages |
| The use of implants increases the cost of surgery. |
| Intraoperative fluoroscopy is necessary to locate the patellar and femoral fixation sites. |
| Harvesting of the semitendinosus autograft may be a source of additional morbidity. |
| Although adjustable buttons offer advantages in tensioning, they may also increase the complexity of the surgical procedure. |
| Although adjustable loops are designed for one-way tensioning, there is a concern about potential loosening and elongation under load. |
| Improper deployment of the adjustable button can lead to soft tissue interposition between the button and bone, potentially causing pain, graft migration, and the need for implant removal or revision. |
| Adjustable-loop devices may be more prone to loosening under cyclic loading than fixed-loop devices. |
Disclosures
All authors (C.K.Y., G.K., A.C.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Supplementary Data
The video describes the surgical technique for medial patellofemoral ligament (MPFL) reconstruction using adjustable loop button fixation in the patella and interference screw fixation in the femur. The procedure is performed on the right knee with the patient in the supine position on the operating table and the knee flexed at 90°. After knee arthroscopy and semitendinosus autograft harvest, MPFL reconstruction is performed using a transverse 6- × 20-mm patella socket and an obliquely oriented 6- × 30-mm femoral socket placed in an anatomic position. The anatomic insertion site of the MPFL is determined using intraoperative fluoroscopy. The semitendinosus tendon autograft is fixed at the patella using an adjustable-loop cortical suspension button and at the femoral socket using an interference screw. The graft is stabilized with the knee in 60° of flexion while the patella is centered in the femoral trochlea using intraoperative visual and fluoroscopic confirmation. Postoperative knee immobilization is not required, and full weight-bearing is immediately allowed.
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Associated Data
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Supplementary Materials
The video describes the surgical technique for medial patellofemoral ligament (MPFL) reconstruction using adjustable loop button fixation in the patella and interference screw fixation in the femur. The procedure is performed on the right knee with the patient in the supine position on the operating table and the knee flexed at 90°. After knee arthroscopy and semitendinosus autograft harvest, MPFL reconstruction is performed using a transverse 6- × 20-mm patella socket and an obliquely oriented 6- × 30-mm femoral socket placed in an anatomic position. The anatomic insertion site of the MPFL is determined using intraoperative fluoroscopy. The semitendinosus tendon autograft is fixed at the patella using an adjustable-loop cortical suspension button and at the femoral socket using an interference screw. The graft is stabilized with the knee in 60° of flexion while the patella is centered in the femoral trochlea using intraoperative visual and fluoroscopic confirmation. Postoperative knee immobilization is not required, and full weight-bearing is immediately allowed.