Arthroscopically Assisted Double-Bundle Medial Patellofemoral Ligament Augmentation With Physeal-Sparing Suture Fixation for Recurrent Patellar Dislocation in Skeletally Immature Patients

Abstract

Recurrent patellar dislocation is a common patellofemoral disease that affects active adolescents. The optimal surgical treatment of recurrent patellar dislocation in skeletally immature patients remains controversial. This Technical Note describes an arthroscopically assisted double-bundle medial patellofemoral ligament (MPFL) augmentation. Orthocord suture, with ideal strength and partial bioabsorbable characteristics, is used as the stabilizer to augment and protect the native MPFL during its biological healing. Under an arthroscope, patellar tunnels are created with Kirshner wire at the upper third point of the medial articular margin and the midpoint of the proximal articular margin. A physeal-sparing transosseous suture fixation technique is applied at the femoral attachment. Two femoral tunnels are made with half-circle cutting needle, which is pierced into the femoral origin of the MPFL and exits the posterior femoral cortex. After dynamic assessments of knee range of motion and patellofemoral congruence, free ends of the Orthocord suture bundle are tied together at the external opening of the femoral tunnel. Transosseous suture fixation balances the requirements of anatomic restoration, reliable fixation, and physeal preservation, and thus may provide a promising alternative to current algorithm of addressing recurrent patellar dislocation in pediatric population.

Fig 1

Schematic illustration of double-bundle medial patellofemoral ligament augmentation with Orthocord suture. (A) Anteromedial view. Patellar tunnels are created from the central area of the front surface (Point C) to the upper third point of the medial articular margin (Point A, tunnel 1) and to the middle of the superior articular margin (Point B, tunnel 2), respectively. Double-strand Orthocord suture is introduced into the patellar tunnel. (B) Posteromedial view. Physeal-sparing transosseous suture fixation is applied on the femoral side. Two femoral tunnels are made with half-circle cutting needle, which is pierced into the femoral origin of the MPFL and exits the posterior femoral cortex. The Orthocord suture is introduced into the femoral tunnel, with its free ends tied together and fixed at the external opening of the tunnel. MPFL, medial patellofemoral ligament.

Fig 2

Location markers of the patellar tunnels. The patient is placed supine on the operating table (left knee). An anterolateral portal and an anteromedial portal are established. (A) Macroscopic view of guide needles. (B) Arthroscopic evaluation of the guide needle at point A through the anterolateral portal. (C) Arthroscopic evaluation of the guide needle at point B through the anterolateral portal. Point A, the upper third point of the medial patella. Point B, the midpoint of the superior patella.

Fig 3

Arthroscopically assisted creation of patellar tunnel 1. The patient is placed supine on the operating table (left knee). An anterolateral portal and an anteromedial portal were established. (A) Macroscopic view of a Kirschner wire (red asterisk) drilling the tunnel. (B) Arthroscopic view of the Kirschner wire through the anterolateral portal. (C) Macroscopic view of a blunt cannula (black asterisk) developing the extracapsular approach. (D) Macroscopic view of a spinal needle (white asterisk) introducing the guide suture into the articular cavity. (E) Arthroscopic view (anterolateral portal) of the spinal needle. (F) Macroscopic view of a penetrating grasper (yellow asterisk) grasping the guide suture. (G) The penetrating grasper is pierced into the capsule to retrieve the looped portion of the guide suture. (H) Double-strand Orthocord suture (yellow arrows) is passed through the patellar tunnel 1 along the guide suture (white arrow). (I) Arthroscopic view (anterolateral portal) of double-strand Orthocord suture (yellow arrow) exiting the capsule. Point A, the upper third point of the medial patella. Point B, the midpoint of the superior patella.

Fig 4

Techniques of retrieving the suture bundle through subcutaneous approach. The patient is placed supine on the operating table (left knee). (A) A subcutaneous approach is created with a blunt cannula (black arrow). (B) A suture retriever (red arrow) is used to retrieve the free end of the Orthocord suture and pull it back via the medial incision. (C) Two limbs (white arrows) of the suture bundle both exit the medial incision. Point A, the upper third point of the medial patella. Point B, the midpoint of the superior patella.

Fig 5

Arthroscopically assisted creation of patellar tunnel 2. The patient is placed supine on the operating table (left knee). An anterolateral portal and an anteromedial portal are established. (A) Macroscopic view of a Kirschner wire (red asterisk) drilling the tunnel. (B) Arthroscopic view (anterolateral portal) of the Kirschner wire. (C) After the guide suture is inserted into the capsule by a spinal needle (white asterisk), a penetrating grasper (yellow asterisk) is introduced through the previously established extracapsular approach. (D) Arthroscopic view of the spinal needle through the anterolateral portal. (E) Arthroscopic view (anterolateral portal) of the penetrating grasper pierced into the capsule to retrieve the looped portion of the guide suture. (F) Double-strand Orthocord suture (yellow arrows) is passed through the patellar tunnel 2 along the guide suture (white arrow). (G) Arthroscopic view (anterolateral portal) of the Orthocord suture (yellow arrow) exiting the capsule. (H) A suture retriever (red arrow) is used to retrieve a free end of the Orthocord suture and pull it back via the medial incision. (I) Two limbs (white arrows) of the suture bundle both exit the medial incision. Point B, the midpoint of the superior patella.

Fig 6

Physeal-sparing suture fixation at femoral origin and arthroscopic re-examination. The patient is placed supine on the operating table (left knee). An anterolateral portal and an anteromedial portal are established. (A) Through a medial incision (white arrow), femoral tunnels are made with a half-circle cutting needle, which are located within the sulcus between the adductor tubercle and medial epicondyle and exit the posterior femoral cortex. (B) Orthocord suture bundles (yellow arrows) are introduced into the femoral tunnels along guide suture and pulled out via the medial incision (white arrow). (C) If the lateral restraints are suggested to be excessively tight, a lateral release is performed with coblation and shaver (red asterisk) close to the lateral margin of the patella from inferior to superior. (D) Arthroscopic re-evaluation via the anterolateral portal demonstrates restored patellofemoral congruence during dynamic passive knee movements. (E) To fix the suture bundles, knots (red dotted circle) are tied using 2 ends of each suture bundle at the external opening of each femoral tunnel through the medial incision (white arrow). (F) Intra-articular view (anterolateral portal) of the double-bundle structure (dotted lines and yellow arrows) of the Orthocord suture.

Fig 7

Comparison of patellofemoral congruence pre- and postsurgery (left knee). (A and C) Intraoperative assessments under arthroscopy. (B and D) Imaging evaluation with axial CT. Arthroscopic evaluation and CT images both demonstrate that the patellofemoral congruence is restored after MPFL augmentation. Yellow dotted line demonstrates the medial margin of the patella, whereas the red dotted line refers to the lateral margin of the patella or the trochlear facet. CT, computed tomography; MPFL, medial patellofemoral ligament; P, patella. T, trochlea.