Clinical Outcome Of Double-bundle Anatomical Medial Patellofemoral Ligament Reconstruction For Patella Dislocation

Objective: Patellar dislocation is a common orthopedic clinical disease, with most cases, the medial patellofemoral ligament (MPFL) was found relaxation, torn, or dysfunction in recent years, especially in the cases with the normal development of bone structure. Biomechanical studies have confirmed that MPFL is the primary, also the important soft tissue inhibiting strength for patellar dislocation. Therefore, MPFL is the main surgical choice for the treatment of patellar dislocation, aimed at restoring the normal anatomy and function. Anatomical study has found that the portion of the MPFL extending from the inferior aspect of its patellar attachment to the superior aspect of femoral attachment was most isometric, with the superior femoral attachment being the most important in the course of knee flexion 0-90 degrees. Based on this, precise femoral ligament graft location was required in clinical isometric reconstruction. Moreover, Function of the MPFL is more dependent on the complexity of the patellar structure, the lamellar structure was vividly described as the water leakage shape, hourglass-shaped, or fan by scholars. Recent studies have pointed out the functional bundle structure: the superior-oblique bundle and the inferior-straight bundle. Therefore, the current clinical anatomical reconstruction, with the basis of the remaintain the isometry of ligament, needs to relocate the femoral anatomical attachment as precise as possible, simulate the lamellar structure of patellar attachment, to restore the physiological function of the maintenance of normal patellar trajectory. This article described the surgery methods of the anatomical double-bundle MPFL reconstruction: within the femur condyle as reference point, a small percutaneous incision to locate femoral position, double-bundle grafts to reconstructe the functinal bundles, the restore the anatomy of native ligament and assessed the effectness of reconstruction through clinical follow-up.Methods: A retrospective analysis of 42 cases (42 knees) with patellar dislocation underwent double-bundle anatomical MPFL reconstruction from January 2008 to December 2009 in the Joint department of Third Hospital of Hebei Medical University. Autologous semitendinosus–gracilis were choosed for grafts, folded from the middle into two shares. Whip stitches are placed in folding end about 2.5 cm, while pullout sutures wrer in the other two ends. The mid-point between medial femoral epicondyle and adductor tubercle and the upper middle 1/3 of the medial margin of patella were initially selected as the femoral and patellar insertion site to check the isometry of graft. In the selected femur point, the bone tunnel was drilled with 7.0-mm in diameter and 25mm-30mm in depth, the suture end was pulled into the blind tunnel through the pullout line and then fixed with a 7.0×23mm bioabsorbable interference screw. Blunt dissection was carried out to create a soft tissue tunnel from the medial border of patella to the medial epicondyle, deep to the medial retinaculum but superficial to the synovium and the free ends of the graft were then pulled through the soft tissue tunnel. Two transverse tunnels were created beneath the prepatellar aponeurosis at supermedial corner and midpoint of medial border of patella to reconstructe the functianal bundles of MPFL: inferior-straight bundle and superior-oblique bundle. With the tension to the ligament, the knee was placed a range of motion and patellar track was monitored under arthroscopy. At 60 degree of knee flexion, whip sutures were performed between the prepatellar aponeurosis and graft to fix the inferior-straight bundle. With the similar motheds, the superior-oblique bundle was sutured at the supermedial corner with the knee at extension. The surgery was with a complement of vastus medialis advancement. In addition, the lower border of vastus medialis obliquus was advanced 5 to 10 mm distally and laterally and sutured on the surface of the reconstructed superior-oblique bundle about 20 mm. Postoperatively knee CT was used to measure the sulcus angle, congruance angle, lateral patellofemoral angle and patella tilting angle. Knee function was assessed by the Kujala and Lysholm scores. Statistical analysis was conducted with the SPSS software (SPSS 13.0 Chicago, III), paired student t test was for comparison between preopertive and lastest follow-up. The significace level was set at P <0.05.Result: All patients were followed up at an average of 13.4±2.7 months. The incisions were healed well without infection, nonunion and deep venous thrombosis occurred. Patellar tilt and extrapolation test were negative and non-recurrent dislocation was occurred at follow-up. On postoperative CT measurement, congruance angle reduced from 21.93±4.58 to 10.90±2.13; lateral patellar angle increased from 2.02±5.54 to 8.33±2.11; patellar tilt angle from 22.19±4.1 to 12.69±1.63, with statistical significance. Joint function was imprved: Kujala score from 57.50±8.03 to 87.69±5.94; Lysholm score from 62.26±5.33 to 92.11±3.54, both were statistically significant.Conclusion: The double-bundle anatomical medial patellofemoral ligament reconstructionfor patellar dislocation, can correct poor patellar track and reduce the subjective symptoms of patients and improve knee function. Short-term clinical observations show non-recurrent dislocation, but long-term follow-up was required to confirm the long-term efficacy.