Femoral interference screw fixation of hamstring and quadriceps tendons for ACL reconstruction

This cadaveric study compares the biomechanical properties of femoral graft fixation in ACL reconstruction of either quadriceps or hamstring tendon grafts with four different interference screws. The hypothesis was that quadriceps tendon grafts provide at least equal results concerning gap formation during cyclic loading and ultimate failure load compared to hamstring tendon grafts with four different interference screws. Eighty porcine femora underwent interference screw fixation of human tendon grafts for ACL reconstruction. Either quadriceps (Q) or hamstring (H) tendon grafts and four different bioabsorbable interference (Wolf (W), Storz (S), Mitek (M), Arthrex (A)) screws were used, resulting in 8 groups with 10 specimens per groups (WQ, WH, SQ, SH, MQ, MH, AQ, AH). Biomechanical analysis included pretensioning the constructs with 60 N for 30 s, then cyclic loading of 500 cycles between 60 and 250 N at 1 Hz in a servohydraulic testing machine, with measurement of elongation and stiffness including video measurements. After this, ultimate failure load and failure mode analysis were performed. No statistically significant difference could be noted between the groups regarding gap formation during cyclic loading [Cycles 21-500 (mm): WQ 3.6 +/- 0.8, WH 3.9 +/- 1.4, SQ 3.6 +/- 0.8, SH 3.3 +/- 1.5, MQ 4.3 +/- 0.8, MH 4.6 +/- 1.0, AQ 4.8 +/- 0.8, AH 4.3 +/- 1.5, n.s.], stiffness during cyclic loading [Cycles 21-500 (N/mm): WQ 72.9 +/- 16.9, WH 71.6 +/- 20.7, SQ 69.5 +/- 23.9, SH 77.4 +/- 25.1, MQ 59.6 +/- 11.2, MH 48.4 +/- 15.4, AQ 48.8 +/- 12.7, AH 51.9 +/- 22.2, n.s.], and ultimate failure load [(N): WQ 474.4 +/- 88.0, WH 579.3 +/- 124.2, SQ 493.9 +/- 105.2, SH 576.0 +/- 90.4, MQ 478.6 +/- 59.0, MH 543.9 +/- 119.7, AQ 480.2 +/- 93.8, AH 497.8 +/- 74.2, n.s.]. Quadriceps tendon grafts yield comparable biomechanical results for femoral interference screw fixation in ACL reconstruction compared to hamstring tendon grafts. From a clinical perspective, quadriceps tendon grafts should therefore be considered as a good option in ACL reconstruction in the future.