Abstract
Medial patellofemoral ligament reconstruction is a common treatment for recurrent patellar dislocation, with long-term follow-up data showing favorable clinical outcomes and high patient satisfaction. Younger female patients, who represent the primary affected population, often prefer minimally invasive surgical incisions, particularly those with keloid-prone skin. In this study, the authors describe a technique for reconstructing the medial patellofemoral ligament by obtaining half of the peroneus longus tendon autograft through a small incision. This approach preserves the function of the peroneus longus muscle and provides good clinical outcomes while minimizing surgical scarring.
Technique Video
Patellar dislocation, a common orthopaedic condition that causes knee pain and damage to articular cartilage, is frequently observed in adolescents.1 The medial patellofemoral ligament (MPFL) plays a critical role in patellar stabilization during early knee flexion by providing medial restraint.2 MPFL injury commonly occurs following strenuous activity or accidental falls associated with first-time patellar dislocation, occurring in up to 94.7% of such cases.3
Initial management of first-time patellar dislocation is typically nonoperative, involving activity restriction with braces,4 quadriceps strengthening, and avoidance of deep knee flexion to prevent recurrence dislocation. However, due to MPFL damage, patellofemoral joint instability persists in many patients, leading to recurrent patellar dislocations. Surgical intervention, especially MPFL repair, is used to reduce the risk of patellar redislocation, although recurrence remains a concern. Tendon grafting has gained wide acceptance for MPFL reconstruction (MPFLR) to restore patellar mechanical stability. Approximately one-third of patients with patellar dislocation undergo MPFLR, with long-term follow-up confirming favorable clinical outcomes and high patient satisfaction.5
MPFLR techniques are now well established, commonly using the quadriceps tendon or semitendinosus tendon as graft material. These methods have shown favorable outcomes.6,7 However, adolescents, especially female patients, often seek not only effective treatment but also minimal postoperative scarring. To address this concern, we selected the peroneus longus tendon as the graft source. This choice minimizes the surgical wound around the knee and offers a cosmetic benefit of a harvest site incision that can be concealed by shoes or socks once healed.
Surgical Technique
The surgical technique is shown in Video 1.
Patient Preparation
The patient is anaesthetized and placed in the supine position on the operating table, and a nonsterile tourniquet is applied around the proximal thigh. The affected limb is sterilized using standard surgical preparation. The knee and ankle joints are fully exposed through surgical draping, and the foot is covered with a sterile glove to prevent contamination.
Autograft Preparation
A 1-cm incision is made above the posterior aspect of the ankle. Two tendons are usually found, the anteromedial peroneal short tendon and the posterolateral peroneal long tendon, and 2 hemostatic forceps are employed to dissect the tendons carefully. Approximately half of the peroneus longus tendon is successfully isolated. The anterior half of the peroneus longus tendon is separated. After distal separation, nonabsorbable sutures (Ethibond Excel; Johnson & Johnson) are used to weave the tendon end using the Krackow method. Usually, 6 suture loops are selected for suture (Fig 1A-C). With the ankle internally rotated by the assistant, the tendon retriever is passed through the caudal end of the tendon, and the muscle tissue is stripped proximally along the longitudinal axis of the peroneus longus until the tendon is extracted (Fig 1D). The muscle tissue at the caudal end of the tendon is removed, the braid is secured with a nonabsorbable suture (1.5 cm), and the diameter and length of the harvested tendon are measured and set aside (Fig 1 E and F).
Fig 1.
Taking the peroneus longus tendon and preparing a tendon autograft. (A) A 1-cm incision above the posterior aspect of the ankle. (B) Separation of the peroneus longus tendon. (C) Nonabsorbable sutures are taken from half of the peroneal longissimus tendon after dissection and braided. (D) The ankle joint varus (red arrow) is turned, and the free end of the peroneus longus tendon (green arrow) is immobilized. The tendon apparatus is used to free the tendon (blue arrow). (E) Measurement of tendon length. (F) The muscular part of the tendon is removed, and the other end of the tendon is braided. The patient is in the supine or supine position, with the affected limb extended. The perspective is on the outer upper side of the affected limb.
Patellar Tunnel Preparation
A 1-cm incision is made at the junction of the medial middle and upper third of the patella. The subcutaneous tissue is bluntly dissected down to the bone. A Kirschner wire is inserted from the medial middle-upper patella toward its midpoint, and a 4.5-mm hollow drill is used to create a tunnel following in the direction of the Kirschner wire (Fig 2). Accurately determining the middle to upper third of the patella is technically challenging. The assistant stabilizes the patella using the thumbs and index fingers of both hands, defines the patellar borders, and identifies the desired entry point via measurement. Based on our experience, this often results in a high anchor point; therefore, we select a site slightly below the upper middle third.
Fig 2.
Establishment of the patellofemoral tunnel. (A) The assistant immobilizes the patella, and a Kirschner wire is used to drill the patellar tunnel in the middle and upper third of the patella. (B) Imaging of the patellofemoral tunnel. The patient is in the supine or supine position, with the affected limb extended and the perspective is in the inner upper part of the affected limb.
Femoral Tunnel Preparation
The longitudinal axis of the knee is aligned perpendicularly to the C-arm fluoroscopy beam. The Schöttle point is identified as the medial starting site of the femoral tunnel, confirmed with lateral knee fluoroscopy. A 1-cm incision is made, and the femoral tunnel is created using 4.5-mm and 6.0-mm hollow drills in the direction of the Kirschner wire (Fig 3). The Schöttle point is typically located on a true lateral radiograph of the knee joint, defined by a tangent to the posterior cortex of the femur and the posterior femoral condyle, marked by a blue guideline.
Fig 3.
Schöttle point (red star) determination and femoral tunneling. (A) With a correct lateral view of the knee, a Schöttle point is localized in the area between the tangent line of the posterior cortex of the femur (red arrow), the tangent line of the posterior condyle of the femur (blue arrow), and a straight line from the superior edge of the femoral condyle perpendicular to the tangent line of the posterior cortex of the femur (green arrow). (B) Kirschner wire polishing of the femoral tunnel. (C) A 4.5-mm drill is used to widen the femoral tunnel. (D) Femoral tunnel and nonresorbable compression screw in imaging performance. The patient is in the supine and supine positions. The affected limb is flexed at 30°, and the viewing Angle is in the inner upper part of the affected limb.
Autograft Reconstruction
The sutures from one end of the graft are threaded through the guiding needle from medial to lateral via the patellofemoral tunnel. Both suture ends are then passed beneath the superficial fascial layer to the Schöttle point incision. The guiding needle passes the sutures through the femoral tunnel at the Schöttle point, enabling proper graft passage through both tunnels (Fig 4A-C). While the knee is flexed and extended, pressure is applied over the femoral tunnel entrance, and the sutures are pulled to adjust the graft tension and assess isometric characteristics (Fig 4D). Optimal tension is defined as allowing one-fourth of patellar lateral displacement under passive external force, with no significant graft elongation during knee flexion and extension. The graft is secured with the knee in 30° of flexion using a nonabsorbable PEEK (polyether ether ketone) extruded screw (BIOSURE PK Screw; Smith & Nephew) (Fig 4 E and F). All surgical incisions measure less than 1 cm after skin closure (Fig 5).
Fig 4.
Autologous tendon graft. (A) A 1-cm incision above the posterior aspect of the ankle. (B) Autologous tendon grafts are introduced into the patellar tunnel. (C) The sutures at the ends of the autologous tendon grafts are introduced into the medial femur proximal to the Schöttle point via the underside of the superficial fascial layer. (D) Fixation of the tendon and flexion and extension of the knee joint to detect isometrics of the tendon. (E, F) Schematic of the end of the tendon in the femoral tunnel of the compression screw to complete ligament reconstruction. The patient is in the supine and supine positions. The affected limb is flexed at 90°, and the viewing Angle is directly above the affected limb.
Fig 5.
All incisions were less than 1 cm after suturing. The patient is in the supine or supine position, with the affected limb extended and the viewing Angle directly above the affected limb.
Discussion
The MPFL is a dense, strip-like fibrous connective tissue composed of 2 functional bundles. When both bundles are reconstructed, the mechanical properties of the native MPFL are better replicated. To minimize patellar trauma and avoid fractures, some surgeons favor single-bundle reconstruction, which has been shown to provide satisfactory clinical outcomes.8 Migliorini et al.9 conducted a cohort study comparing MPFLR techniques and found that double-bundle reconstructions resulted in significantly better clinical outcomes than single-bundle ligament reconstruction. Similarly,Wu et al.10 reported better knee function, reduced dislocation rates, and improved clinical outcomes with double-bundle reconstruction compared to single-bundle repairs.
Fixation in the medial middle to upper third of the patella is typically selected during MPFLR. Positioning the fixation point either too proximal or too distal can compromise the graft’s isometric properties, leading to patellar instability or knee motion restriction.11 The use of double-bundle tendon reconstruction on the patellofemoral side, with one end fixed via a patellar tunnel and the other at the femoral origin, effectively replicates MPFL anatomy and is the most commonly used method of MPFLR. This method reduces reliance on anchors or compression screws, lowering surgical costs and avoiding implant-related complications.
Schöttle et al. (2007)12 proposed identifying the MPFL femoral origin using lateral knee fluoroscopy, a method now widely adopted. Studies indicate that femoral tunnel positioning errors greater than 10 mm correlate with poor clinical outcomes, including patellar redislocation. In fact, 31% to 67% of MPFL revision procedures are due to tunnel misplacement.13 However, the tension and laxity of the reconstructed ligament depend not only on the accuracy of bone tunnel localization but also on the proper assessment of tendon tension through passive knee movement before fixation and isometric testing. Biomechanical analyses have shown that a change in tendon length of less than 5 mm between knee flexion and extension is considered isometric. Fixation of the tendon between 30° and 60° of knee flexion can minimize significant changes in tendon length during full knee extension or flexion.14 Walsh et al.15 concluded that when the difference between the femoral tunnel diameter and the graft tendon diameter is equal to or greater than 2 mm, such fixation not only prevents anterior migration of the tendon, thereby maintaining joint stability, but also avoids excessive tightness that could impair knee flexion activity.
With improvements in surgical techniques and increased clinical experience, patients can resume normal activities and participate in daily exercise or even contact sports following MPFLR. Long-term follow-up has shown favorable outcomes. However, approximately 60% of MPFLR procedures are performed in female patients with recurrent patellar dislocation, with the average age of these patients being approximately 24 years.16
The use of the peroneus longus tendon as a graft enables both good clinical outcomes and smaller surgical incisions, resulting in improved patient satisfaction. The advantages and disadvantages of this surgical technique are summarized in Table 1, whereas technical tips and pitfalls are listed in Table 2.
Table 1.
Advantages and Disadvantages of the Technique
| Advantages | Disadvantages |
|---|---|
| When using the peroneus longus tendon, the incision is small and can be easily concealed. | Presence of surgical incisions away from the operative area. |
| Reduces soft tissue damage and exposure and facilitates wound healing and recovery. | Possibility of patellar cartilage injury and fracture. |
| Only 1 compression screw is used, making it more cost-effective. | Inability to resolve high or low patella, femoral trochanteric deformity, and tibial tuberosity exostosis (high TT-TG values). |
| Double-bundle tendon reconstruction facilitates fan-shaped distribution of force and more closely resembles the normal anatomy of the MPFL. |
MPFL, medial patellofemoral ligament; TT-TG, tibial tuberosity–trochlear groove.
Table 2.
Tips and Pitfalls of the Technique
| Tips | Pitfalls |
|---|---|
| Accurately identify the peroneus longus muscle, which is located posterolaterally, and the peroneus brevis muscle, which is located medially anteriorly. | Exclude patients with ankle disease to avoid aggravation of existing ankle disease after removal of the peroneus longus tendon. |
| When removing the tendon, turn the ankle joint inward to maintain a certain degree of tension on the tendon, which facilitates the smooth removal of the tendon and reduces the risk of tendon rupture. | Tendon harvesting is performed by a senior physician to avoid tendon disruption, and it is advisable to prepare a second option to prevent insufficient tendon length from interfering with the surgical process. |
| Measure the diameter of the tendon to ensure that the diameter of the femoral tunnel is greater than the diameter of the tendon to avoid difficulty in passing the graft through the femoral tunnel. | When preparing the patellar tunnel, the height of the upper and lower poles of the patella is clarified, and the assistant stabilizes the patella and drills the bone tunnel diagonally upward in the middle and upper third of the patella to avoid patellar fracture. |
| After ligament reconstruction is completed, the patella’s trajectory should be examined arthroscopically, and the patella can be passively moved outward by about one-fourth of the patella’s width when the knee is in the straight position, to avoid excessive tension limiting the knee’s activity. | It is important to localize the point of opening of the femoral tunnel, which must be done in the fully lateral position (overlapping medial and lateral femoral condyles). |
| We chose to bend the knee at 30° for femoral tunnel interface screw fixation of the tendon, and we believe that isometrics are optimal. | |
| If flexion is limited due to ligamentous tension after ligament reconstruction, a lateral patellofemoral release may be performed. |
Disclosures
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Y.S. is an employee of the Institute of Hygiene in the Arms Industry and has a pending patent (No. KY202408) with the Institute of Hygiene in the Arms Industry. M.W. is an employee of the Institute of Hygiene in the Arms Industry and has a pending patent (No. KY202408) with the Institute of Hygiene in the Arms Industry. Y.Y. is an employee of the Institute of Hygiene in the Arms Industry and has a pending patent (No. KY202408) with the Institute of Hygiene in the Arms Industry. B.W. is an employee of the Institute of Hygiene in the Arms Industry and has a pending patent (No. KY202408) with the Institute of Hygiene in the Arms Industry. J.L. is an employee of the Institute of Hygiene in the Arms Industry and has a pending patent (No. KY202408) with the Institute of Hygiene in the Arms Industry. Z.Z. is an employee of the Institute of Hygiene in the Arms Industry and has a pending patent (No. KY202408) with the Institute of Hygiene in the Arms Industry.
Funding
This work was supported by the Institute of Hygiene in the Arms Industry, Institute-Level Development Fee Program (No. KY202408).
Footnotes
Y.S., and Y.Z. are co-first authors.
Supplementary Data
In arthroscopically significant patellar ectopia, half of the peroneus longus tendon is taken from the posterior superior aspect of the ankle, the distal part of the tendon is braided after it is cut off, and the tendon is removed by inversion of the ankle using the tendon extractor. Remove the muscle tissue attached to the tendon, measure the length of the tendon, and prepare the patellar tunnel in the medial middle and upper third of the patella. A C-arm fluoroscopic lateral radiograph of the femur localizes the Schöttle point. Prepare the femoral tunnel with 30° flexed knees. The tendon is guided through the patellar tunnel, and the lateral free end of the tendon is reflected back to the medial patella underneath the fascial layer. Adjust the tendon length and suture the patellar tendon. The 2 free end tendons are guided through the superficial fascia inferiorly to the femoral tunnel localization point. Fixate both femoral tendons at the Schöttle point and complete flexion of the knee to check the isometric length of the tendons and to avoid restriction of knee movement. Pass the free ends of both femoral tendons through the femoral tunnel and fix them with interface screws. After completion of ligament reconstruction, arthroscopically explore patellar external displacement and match the patella to the femoral trochanter. All surgical incisions are less than 1 cm, and postoperative review shows a good position of the patellofemoral tunnel.
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
In arthroscopically significant patellar ectopia, half of the peroneus longus tendon is taken from the posterior superior aspect of the ankle, the distal part of the tendon is braided after it is cut off, and the tendon is removed by inversion of the ankle using the tendon extractor. Remove the muscle tissue attached to the tendon, measure the length of the tendon, and prepare the patellar tunnel in the medial middle and upper third of the patella. A C-arm fluoroscopic lateral radiograph of the femur localizes the Schöttle point. Prepare the femoral tunnel with 30° flexed knees. The tendon is guided through the patellar tunnel, and the lateral free end of the tendon is reflected back to the medial patella underneath the fascial layer. Adjust the tendon length and suture the patellar tendon. The 2 free end tendons are guided through the superficial fascia inferiorly to the femoral tunnel localization point. Fixate both femoral tendons at the Schöttle point and complete flexion of the knee to check the isometric length of the tendons and to avoid restriction of knee movement. Pass the free ends of both femoral tendons through the femoral tunnel and fix them with interface screws. After completion of ligament reconstruction, arthroscopically explore patellar external displacement and match the patella to the femoral trochanter. All surgical incisions are less than 1 cm, and postoperative review shows a good position of the patellofemoral tunnel.