Effects of Suture Choice on Biomechanics and Physeal Status After Bioenhanced Anterior Cruciate Ligament Repair in Skeletally Immature Patients: A Large-Animal Study

Abstract

The objective of this study was to assess the effect of absorbable or nonabsorbable sutures in bioenhanced anterior cruciate ligament (ACL) repair in a skeletally immature pig model on suture tunnel and growth plate healing and biomechanical outcomes. Sixteen female skeletally immature Yorkshire pigs were randomly allocated to receive unilateral, bioenhanced ACL repair with an absorbable (Vicryl) or nonabsorbable (Ethibond) suture augmented by an extracellular matrix-based scaffold (MIACH). After 15 weeks of healing, micro-computed tomography was used to measure residual tunnel diameters and growth plate status, and biomechanical outcomes were assessed. At 15 weeks postoperatively, there was a significant difference in tunnel diameter with significantly larger diameters in the nonabsorbable suture group (4.4 ± 0.3 mm; mean ± SD) than in the absorbable group (1.8 ± 0.5 mm; P < .001). The growth plate showed a significantly greater affected area in the nonabsorbable group (15.2 ± 3.4 mm(2)) than in the absorbable group (2.7 ± 0.8 mm(2), P < .001). There was no significant difference in the linear stiffness of the repairs (29.0 ± 14.8 N/mm for absorbable v 43.3 ± 28.3 N/mm for nonabsorbable sutures, P = .531), but load to failure was higher in the nonabsorbable suture group (211 ± 121.5 N) than in the absorbable suture group (173 ± 101.4 N, P = .002). There was no difference between the 2 groups in anteroposterior laxity at 30° (P = .5117), 60° (P = .3150), and 90° (P = .4297) of knee flexion. The use of absorbable sutures for ACL repair resulted in decreased physeal plate damage after 15 weeks of healing; however, use of nonabsorbable sutures resulted in 20% stronger repairs. Choice of suture type for ACL repair or repair of tibial avulsion fractures may depend on patient skeletal age and size, with absorbable sutures preferred in very young, small patients at higher risk with physeal damage and nonabsorbable sutures preferred in larger, prepubescent patients who may place higher loads on the repair.