In all-inside anterior cruciate ligament (ACL) reconstruction, it is usually difficult to obtain sufficient autologous semitendinosus tendon length for quadruple stranded graft in Asians, females, and those with short stature. The purpose of this study was to compare biomechanical properties of three different types of suture preparations for tripled graft and determine which method could achieve sufficient strength for ACL through in vitro study. The hypothesis of this study was that suturing with a rip-stop (RS) stitch for tripled-strand graft would lead to stronger mechanical properties than suturing with buried-knot four sutures.

Twenty-four bovine digital extensor tendons harvested from forelimbs were prepared for tripled-strand graft in three different ways: (1) buried-knot four sutures, (2) two RS sutures, and (3) four RS sutures. These grafts were directly connected to cylindrical metal rods of a tensile testing machine. All specimens underwent cyclic loading followed by a load-to-failure test. Preparation time, elongation, stiffness, and ultimate failure load were compared.

For biomechanical comparison, the group with buried-knot four sutures was excluded because six (75%) specimens failed during the cycle load test. The group with four RS sutures showed lower total elongation (two RS sutures: 8.42±5.28mm; four RS sutures: 3.86±0.83mm, p=0.030), higher stiffness (two RS sutures: 247.28±53.39N/mm; four RS sutures: 329.27±55.56N/mm, p<0.001), and higher ultimate failure load (two RS sutures: 567.74±60.50N; four RS sutures: 736.46±32.50N, p=0.009). The most common failure mechanism of triple stranded graft was tendon split across sutures.

The method with four RS sutures showed sufficient strength for triple stranded graft for all-inside ACL reconstruction without increasing preparation time.

III, controlled laboratory study.