Objectives: The objectives of this study was to prospectively investigate the clinical and radiologic outcome at a follow-up five years after isolated double-bundle (DB) medial patellofemoral ligament (MPFL) reconstruction using patellar suture anchor fixation with hamstring autograft.
Methods
Between March 2013 and February 2017, isolated DB MPFL reconstruction was performed on patients with recurrent patellar instability. The contraindication for isolated MPFL reconstruction without additional bony procedure was severe anatomic abnormalities, such as high degree of trochlea dysplasia (Dejour type D) and abnormal tibial tuberosity–trochlear groove distance(TT-TG=20mm). Clinical and functional evaluations were performed by interview using Kujala score, Lysholm score, and Tegner score preoperatively, at 6, 12, 24, and 60 months after surgery. Radiographs were taken preoperatively, postoperatively, at 24 and 60 months after surgery. Patella height was measured using the modified Insall-Salvati (MIS) ratio. Patella tilt angle was measured using the congruence angle (CA) and lateral patella-femoral angle (LPFA). The type of femoral trochlear dysplasia was classified in lateral radiographs according to Dejour et al. The tibial tuberosity–trochlear groove (TT-TG) distance was measured by preoperative MRI.
Results
Thirty-one patients (31 knees) underwent isolated MFPL reconstruction, but four patients failed to follow-up for more than 5 years. A total of 27 patients (27 knees) were enrolled in this study. The mean age at the time of surgery was 22.0 ± 6.4 years (range, 14-32 years). A significant improvement in all clinical and functional score was observed at the each consecutive follow-up for 2 years postoperatively (p < 0.001). There was no significant difference between 2-years and 5-years follow-up. The mean preoperative Kujala score was 52.7±11.7, it gradually increased to 90.7±4.1 until 24 months after surgery(p < 0.001), and it maintained to 91.1±4.8 at 60 months postoperatively. The mean preoperative Lysholm score was 49.6±10.1, it gradually increased to 92.7±3.3 until 24 months after surgery(p < 0.001), and it maintained to 93.3±2.6 at 60 months postoperatively. The mean preoperative Tegner score was 2.9±0.8, it gradually increased to 5.1±1.0 until 24 months after surgery(p < 0.001), and it maintained to 5.2±0.9 at 60 months postoperatively. All radiographic assessments were significantly improved between preoperatively and postoperatively(p<0.001); modified Insall-Salvati index changed from 1.71 to 1.6, CA changed from 5.7°to -6.8°, and LPFA changed from 3.0°to 5.9°. There was no significant difference between all the follow-up evaluations after surgery. According to the criteria of Dejour, 11 knees had no trochlear dysplasia and 16 had trochlear dysplasia. The mean preoperative TT-TG was 15.5 ± 4.2 mm; 13 patients had a TT-TG of =15 mm, and 14 patients had a TT-TG of 15–20 mm. No patient experienced patellar re-dislocation between surgery and 5 years after surgery. There were no complications, such as patellar fracture or infection.
Conclusion
The clinical and radiological outcomes of isolated DB MPFL reconstruction are significantly improved and are maintained until 5 years postoperatively without re-dislocation. The present study suggest that the efficacy and longevity of isolated DB MPFL reconstruction are maintained for 5 years postoperatively.