Optimization location of femoral attachment in medial patellofemoral ligament reconstruction assisted with arthroscopy for patellar dislocation

Abstract

To investigate the technique of optimizing the location of femoral attachment in medial patellofemoral ligament (MPFL) reconstruction assisted with arthroscopy and evaluate the effectiveness. Between January 2014 and September 2018, 35 patients with patellar dislocation were admitted. There were 14 males and 21 females with an average age of 22.6 years (range, 16-38 years). All patients had a history of knee sprain. The disease duration ranged from 1 to 7 days (mean, 2.8 days). Patellar dislocation occurred 2-4 times (mean, 2.5 times). The preoperative Lysholm score and Kujala score were 47.60±11.24 and 48.37±9.79, respectively. The patellar congruence angle was (31.40±6.81)°, the patellar tilt angle was (29.95±5.44)°, the lateral patellofemoral angle was (-11.46±5.18)°, and the tibial tubercle-trochlear groove distance was (16.66±1.28) mm. All patients were treated by MPFL reconstruction with the semitendinosus tendon under arthroscopy. During operation, the suture anchors were inserted into the midpoint and the 1/3 point of superomedial edge of the patella. Then, the femoral tunnels were created in medial femoral condyle through limited excision. For tendon fixation, the Kirschner wires were inserted into adductor tubercle, medial epicondyle of femur, and the midpoint between the two points, as well as the anteriorly and posteriorly. Afterwards, the changes of ligament length and tension, patellar tracking, and the relationship of patella and femoral trochlea were evaluated, thereby determining the optimized femoral attachment for MPFL reconstruction. Finally, the patellar congruence angle, patellar tilt angle, and lateral patellofemoral angle were measured by imaging to assess the relationship of patella and femoral trochlea. Moreover, Lysholm score and Kujala score were used to evaluate the knee joint function. All incisions healed by first intention without infection. All patients were followed up 12-18 months (mean, 15.4 months). At 12 months, the Lysholm score was 94.40±3.99 and the Kujala score was 92.28±4.13, which were significant higher than those before operation ( P<0.05). No patellar dislocation occurred during follow-up. At 12 months, the patellar congruence angle was (6.57±4.59)°, the patellar tilt angle was (9.73±2.82)°, the lateral patellofemoral angle was (7.14±4.63)°, which were superior to those before operation ( P<0.05). During the MPFL reconstruction under arthroscopy, a higher positioning accuracy for the femoral attachment and satisfactory effectiveness can be obtained by evaluating MPFL length and tension, patellofemoral joint kinematics, and patellar tracking.