Medial Patellofemoral Ligament Reconstruction in a Revision Setting: Anchor and Interference Screw Fixation

Abstract

Recurrent patellar instability is a common pathology and typically affects younger and more active patients. To prevent complete lateral dislocation of the patella, several osseous and soft-tissue procedures have been previously described, including reconstruction of the medial patellofemoral ligament (MPFL), which has been identified as the primary medial stabilizer of the patella. Several techniques have been reported for reconstruction of the MPFL, sometimes in conjunction with other procedures, with the majority showing success in the treatment and resolution of patellar instability. However, MPFL reconstruction is not free of complications, with previous reports of recurrence of medial patellar instability and patellar fracture after surgery. The objective of this Technical Note is to describe our preferred technique, comprising anchor as well as interference screw fixation, for reconstruction of the MPFL in a primary or revision setting.

Fig 1

To perform a medial patellofemoral ligament reconstruction in a left knee, the medial border of the patella (P) is used as a reference. Usually, a 5-cm parapatellar incision is made to access and prepare the patella for graft fixation. In this case the incision was extended to the tibial tubercle as a result of a concomitant osteochondral allograft transplant onto the patella.

Fig 2

Following the skin incision, blunt dissection of the subcutaneous tissue is performed to expose the medial retinaculum of the left knee. A 5-cm medial arthrotomy is performed to evaluate the medial border of the patella (P).

Fig 3

After the medial arthrotomy is performed in the left knee, the adductor tubercle is identified and, through palpation, the previous graft location is evaluated. (A, B) Metzenbaum scissors are used to release the graft (arrows), which is first removed from its femoral attachment. (C) The layers between the previous graft are released from any adhesions through use of Metzenbaum scissors and a Mixter clamp (arrow) with the goal of creating a soft-tissue tunnel that will accommodate the graft.

Fig 4

(A) The medial border of the patella (dotted line) in the left knee is identified. By use of a combination of a rongeur and coagulator, all soft tissues are removed from the medial patella to create a bony bleeding surface. (B) Once the patella is prepared, two deep closed-socket tunnels are formed using a 3.2-mm drill (arrow).

Fig 5

To prepare the femoral attachment of the medial patellofemoral ligament in the left knee, the adductor tubercle is used as a reference. (A) A guide pin (arrow) is drilled 3 mm distal to the adductor tubercle and passed to the other side of the thigh. Fluoroscopic imaging can be used to ensure optimal positioning at this time. By use of an acorn reamer, the size of which varies depending on the width of the semitendinosus tendon graft harvested, a closed-socket tunnel is performed. (B) A passing suture (arrow) is passed inside the tunnel to allow for graft fixation. (C) The graft is secured onto the femur (green arrow), whereas the two limbs of the graft are left unconstrained for further fixation on the patella (black arrows).

Fig 6

(A) Once the semitendinosus graft is secured to the femur in the left knee, both ends of the graft (arrows) are passed inside the previously formed soft-tissue tunnel. (B) The optimal position of the patella, as the ends of the graft (arrows) are manipulated, is identified to avoid iatrogenic medial patellar dislocation or an insufficient correction resulting in chronic lateral patellar instability. (C) Each end of the semitendinosus graft is secured onto the patella by use of two 4.75-mm SwiveLock anchors with FiberTape and No. 2 suture. After this, excess graft (arrows) is removed.