Patellar Fracture After Medial Patellofemoral Ligament Surgery

Abstract

The medial patellofemoral ligament (MPFL) has been identified as the primary medial restraint to prevent lateral patellar displacement; it contributes up to 80% of the medial restraining forces on the patella1,2. Anatomically, the MPFL originates from the superior two-thirds of the medial patellar border and runs posteriorly toward the medial femoral epicondyle to insert in close relation to the origin of the superficial medial collateral ligament and slightly distal to the adductor tubercle3-5. Several techniques of MPFL repair and reconstruction have been described, with various graft options, tunnel placements, and fixation options, with or without concomitant procedures such as lateral retinacular release or tibial tuberosity osteotomy. Most techniques for patellar attachment of a reconstructed MPFL use patellar tunnels6-8, while some use suture anchors or soft-tissue fixation7,9,10. The potential complications of MPFL surgery include iatrogenic medial instability, persistent or recurrent lateral instability, patellofemoral arthrosis, loss of knee motion, and patellar fracture. In 1992, in a series of thirty patients, Ellera Gomes11 reported the first patellar fracture after MPFL reconstruction with use of a transverse patellar tunnel that traversed the entire width of the patella. Since then, eight patellar fractures have been reported after MPFL reconstruction with use of patellar bone tunnels. Four fractures in three series7,12,13 were attributed to technical errors associated with patellar tunnel placement. The other four fractures14,15 were medial rim avulsion fractures of the patella after MPFL reconstruction as the treatment for recurrent patellar dislocation. Fractures of the superior pole of the patella (superior pole sleeve avulsions) have been reported after medial soft-tissue imbrication and lateral retinacular release16-18; to our knowledge, similar proximal patellar fractures have not …