Patellar endobutton fixation technique in the MPFL reconstruction

Purpose: Reconstruction of the MPFL has become a popular procedure for treatment of patellofemoral instability. Several techniques of MPFL reconstruction have been described in the literature with good clinical and radiological outcomes. Despite good outcomes, significant rate of complications have observed with these techniques. The purpose of this study was to evaluate the clinical and radiological results of a patella fixation technique using an Endobutton suspensory fixation device dur¬ing MPFL reconstruction. Methods: The study included 28 patients (10 males and 18 females) who underwent MPFL reconstruction with an ipsilateral semitendinosus tendon autograft. The average age of the patients was 24.9 ± 11.6 years (range, 14 to 57 years), and the average follow-up period was 18,5 ± 9 months (range, 12 to 40 months). Graft was fixed using an Endobutton suspensory fixation device in a single ellipsoidal blind tunnel at the medial margin of the patella. Free end of the loop graft was fixed with an interference screw at the femoral tunnel. Clinical scores (Kujala score, Lysholm score, Tegner activity score and VAS score) were assessed preoperatively and at the time of final follow-up. In addition, patients were examined for any complication. Radiographic parameters such as congruence angle, lateral patellofemoral angle, patellar tilt angle and Insall-Salvati ratio were measured before and after surgery. Results: The Tegner activity score improved from 3,95 ± 0,9 to 7,64 ± 1,62 at final follow-up (p< 0,001). The Lysholm score significantly improved from 57,36 ± 12,1 to 87,64 ± 8,48 (p< 0,001). The Kujala score was significantly increased from an average of 56,64 ± 8,87 preoperatively to 82,55 ± 9,05 (p< 0,001). And the VAS score improved from 6,64 ± 1,99 to 0,95 ± 1,09 (p<0,001). The Insall-Salvati ratio significantly changed from 1,2 ± 0,32 to 1,04 ± 0,22 postoperatively (p< 0,001). The congruence angle significantly improved from 18,6° ± 6,3° before surgery to 2,3° ± 4,2° at final follow-up (p< 0,001). The patellar tilt angle had significant improvement from 20,6° ± 6,3° before surgery to 10,18° ± 4,55° at the last follow-up (p< 0,001). The Lateral patellofemoral angle had significant improvement from −0,5° ± 3,8° before surgery to 4,3° ± 2,3° at the last follow-up (p<0,001). Any patellar redislocation or infection were observed in this study. However, loss of knee flexion was observed in one patient and patellar fracture occured in another patient. Conclusion: Graft fixing with an Endobutton suspensory fixation device in a single ellipsoidal blind patellar tunnel is a quite successful technique associated with good clinical and radiological results. With this technique, the physiological kinematics and stability in MPFL reconstruction, are provided anatomically and safely to avoid complications. Keywords: MPFL reconstruction, patellar dislocation, patellar instability, Endobutton, blind tunnel.