Semitendinosus Tendon Transfer Associated With Distal Alignment for Patella Alta in a Patient With Recurrent Dislocations

Abstract

Patellofemoral instability is characterized by pain during normal daily activities and frequent dislocation events. In the reported case, an adolescent girl, aged 15 years, affected by left patellofemoral instability, underwent surgery with a double technique comprising tibial tubercle distalization and medial patellofemoral ligament reconstruction. In case of patella alta associated with patellofemoral instability, surgical treatment should focus on medial patellofemoral ligament repair and on recurrent instability prevention. P atellofemoral instability is characterized by pain during normal daily activities and frequent dislocation events. This pathologic condition is usually associated with patella alta (increase of Caton-Deschamps index [normal value (n.v.) In the reported case, an adolescent girl, aged 15 years, affected by patellofemoral instability, underwent surgery with a double technique comprising TT distalization and medial patellofemoral ligament (MPFL) reconstruction (Video 1). The patient came to our attention after the third episode of left patellar dislocation; a radiographic control obtained in the emergency department showed a patellar avulsion at the MPFL insertion level. On the basis of clinical and imaging examination findings (radiography, magnetic resonance imaging, computed tomography [CT] scan), we decided to perform surgical treatment 2 (Fig 1). Surgical TechniqueThe patient is placed in the supine position on the operating table and examined under anesthesia for the assessment of patellar kinematics during passive knee flexion before inflation of the tourniquet. A lateral thigh post helps to stabilize the femur during the wide range of motion required for the procedure. A tourniquet is placed high on the thigh and inflated with the knee flexed to limit its effect on muscle balance. We suggest placing a fluoroscopy device on the opposite side.A medial parapatellar approach is performed, extending distally to the entire length of the anterior TT. Dissection is performed to expose the attachment of the patellar tendon to the TT (Video 1).The edges of the patellar tendon and the entire tibial tuberosity are drawn with a suitable marker to perform measurements of their lengths (Fig 2). The length of the tibial crest fragment (at the distal edge of the TT) to be removed is measured in a similar manner to obtain the amount of TT distalization required, as decided during preoperative planning. The length of the distal tibial crest fragment excised determines the correction of patellar height (Video 1).The line of the next TT osteotomy is then marked by electrocautery, with care taken to leave the pes anserinus intact. The semitendinosus tendon (ST) graft is harvested. With the surgeon taking advantage of the surgical incision, the pes anserinus is well identified. A longitudinal incision of the sartorius fascia is made along the medial edge of the pes anserinus and is extended proximally in a reverse-L shape. The flap thus obtained is