The single-suture technique for anterior cruciate ligament graft preparation provides similar stability as a three-suture technique: a biomechanical in vitro study in a porcine model

Abstract

Purpose: Numerous techniques have been described for the tibial-sided graft preparation in anterior cruciate ligament (ACL) reconstruction. The use of less suture material for graft preparation is thought to improve ingrowth and to reduce the risk for infection. At the same time, the suture construct should be strong enough to resist the surgeon's pull during tensioning of the transplant.

Methods: In total, 39 fresh-frozen procine deep flexor tendons were used and prepared as four-strand grafts. In the three-suture group (n = 19), graft preparation was performed using three tibial-sided sutures, with each tendon end sutured separately. In the one-suture group (n = 20), a modified graft preparation using only one tibial-sided suture was applied. Each sample underwent load-to-failure testing (N_max) after cyclic pre-loading. To estimate intraoperative tension forces acting on the tibial-sided suture constructs, the maximal tension force of 26 volunteers on such a construct was measured using a load cell.

Results: The biomechanical testing of the two different suture constructs showed a significantly higher load-to-failure for the three-suture group (711 N ± 91 N) compared to the one-suture group (347 N ± 24 N) (p = 0.0001). In both groups, the mode of failure was a tear of the suture in all samples. A failure of the suture-tendon interface was not observed in any case. The median maximal tension force on the construct applied by the 26 volunteers was 134 N (range 73-182 N).

Conclusion: The presented single-suture tendon graft preparation resisted to smaller failure loads than the conventional three-suture technique. However, no failures in the suture-tendon interface were seen and the failure loads observed were far beyond the tension forces that can be expected intraoperatively. Hence, the single-suture graft preparation technique may be a valuable alternative to the conventional technique.

Keywords: ACL reconstruction; Anterior cruciate ligament; Arthroscopy; Biomechanics; Hamstring graft; Patient safety.

Fig. 1

The conventional three-suture technique. a Separate suture fixation of each end of the tendon. b Forming a tendon loop. c Third suture pulled around the midpoint of the tendon. d Final four-strand graft with three tibial-sided sutures

Fig. 2

The one-suture technique. a Combined fixation of both ends of the tendon with one suture. b Forming a tendon loop. c Pulling the suture with the combined tendon ends through the midpoint of the tendon. d Final four-strand graft with one tibial-sided suture

Fig. 3

Testing setup. a Three-suture technique. b One-suture technique

Fig. 4

Setup for measuring the surgeon’s tension force. The suture is looped around a hook that is connected to a load cell

Fig. 5

Boxplot graph showing failure loads and simulated surgeon’s maximum tension force