Objective To measure the tensile strength of the normal medial patellofemoral ligament (MPFL), and evaluate the biomechanics of different fixation methods of the hamstring tendon graft on the patella. Methods Eight fresh cadaver knees were prepared by isolating the patella, leaving only the MPFL as its attachment to the medial condyle of femur. The MPFL was reconstructed by three different methods: four-suture fixation, anchors-single suture fixation, and anchors-double suture fixation. The tensile strength and the elongation of the normal MPFL and the tendon grafts were measured. Results The tensile strength of the four-suture fixation group (234.86±49.02 N) was stronger than that of the normal MPFL (146.91±25.30 N, P=0.0014) and the anchors-single suture group (159.17±49.07 N, P=0.0077), while weaker than that of the anchors-double suture group (314.74±78.46 N, P=0.0052) Conclusions With regard to the tensile strength, the four-suture fixation method is reliable for clinical use. Compared with the anchor-suture method, the four-suture fixation method which has no specific implants is more economical, convenient and efficient.

Key words: medial patellofemoral ligament, biomechanics, fixation method, hamstring tendons